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Rubber compositions

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Information

  • Patent Grant
  • 6172157
  • Patent Number
    6,172,157
  • Date Filed
    Thursday, February 19, 1998
    26 years ago
  • Date Issued
    Tuesday, January 9, 2001
    23 years ago
Information
Abstract
A rubber composition prepared by blending 15 to 85 parts by weight of silica per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber and 1 to 15% by weight of a dispersion-improving agent based on the amount of the silica described above. Further, a rubber composition prepared by blending 20 to 60 parts by weight of silica and 30 to 80 parts by weight of carbon black having a cetyl trimethylammonium bromide-adsorbing amount (CTAB) of 120 m2/g or more and a dibutyl phthalate-absorbing amount (DBP) of 120 ml/100 g or more per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber, and 3 to 15% by weight of a dispersion-improving agent based on the amount of the silica described above, wherein the total amount of silica and carbon black is 50 to 120 parts by weight. A specific nitrogen-containing carbonyl compound or silicone oil is used as a dispersion-improving agent.
Description




TECHNICAL FIELD




The present invention relates to a rubber composition blended with silica, more specifically to a rubber composition which is lowered in a Mooney viscosity and is improved in a low heat generating property and an abrasion resistance by improving the dispersibility of silica in rubber.




Further, the present invention relates to a rubber composition in which the dispersibility of silica is improved and efficient vulcanization is effectuated. Accordingly, the present invention relates to a rubber composition which improves a performance such as a braking property on a wet road (hereinafter called “wet performance”), a performance such as driving stability on a dry road (hereinafter called “dry performance”) and an abrasion resistance for a tire in which the rubber composition described above is applied to a tread thereof.




BACKGROUND ART




Carbon black has so far been used as a reinforcing filler for rubber. This is because carbon black has a high reinforcing property and an excellent abrasion resistance as compared with those of other fillers. In recent years, under the circumstances of socially demanding for saving energy and natural resources, particularly in order to save a fuel consumption of automobiles, a reduction in heat generation of a rubber composition has come to be required at the same time.




In the case of intending a reduction in a heat generation of a rubber composition by virtue of carbon black, it is considered to fill a small amount of carbon black or to use carbon black having a large particle size. In either method, however, it is well known that a reduction in the heat generation has an antinomic relation with the reinforcing property and the abrasion resistance.




On the other hand, silica is known as a filler for reducing heat generation for a rubber composition, and there have so far been filed many patents such as Japanese Patent Application Laid-Open No. Hei 3-252431, Japanese Patent Application Laid-Open No. Hei 3-252433, Japanese Patent Application Laid-Open No. Hei 4-224840, Japanese Patent Application Laid-Open No. Hei 5-51484 and Japanese Patent Application Laid-Open No. Hei 5-271477.




Further, with respect to a tire tread, it is known that the wet skid characteristic is improved by blending a rubber composition for a tire tread with silica. On the other hand, however, the defect that the abrasion resistance is lowered is involved therein at the same time. Accordingly, a rubber composition blended with a vulcanization-controlling silane coupling agent is reported as a composition for solving the defect of reducing the abrasion resistance in a silica-blended tread (Japanese Patent Application Laid-Open No. Sho 61-4742).




Further, known are a rubber composition comprising a polymer blended with a specific amount of carbon black and a specific amount of silica and silane coupling agent (Japanese Patent Application Laid-Open No. Hei 5-271,i ) and a rubber composition for a tire tread improved in an abrasion resistance and a wet skid characteristic by virtue of specific silica and specific carbon black and devising a in kneading process, and a production process for said rubber composition (European Patent No. 501227). Further, known is a technique of blending a rubber composition for a tread comprising a specific polymer and specific carbon black with silica in order to improve the wet skid characteristic and the abrasion resistance, (Japanese Patent Application Laid-Open No. Hei 7-48476, Japanese Patent Application Laid-Open No. Hei 7-90122 and Japanese Patent Application Laid-Open No. Hei 8-73657).




However, silica tends to cause coagulation between the grains thereof by virtue of hydrogen bonds among silanol groups which are surface functional groups, and therefore the kneading time has to be extended in order to improve the dispersibility of silica in rubber. The insufficient dispersibility of silica in rubber brings about a problem that the rubber composition is increases its Mooney viscosity and is inferior in processability such as extrusion.




Further, there has been a problem that since the surface of silica grains is acidic, the grains adsorb a base material used as a vulcanization accelerator in vulcanizing the rubber composition and therefore the vulcanization is not sufficiently carried out, so that the elastic modulus is not enhanced.




Further, there is another problem that since the dynamic storage elastic modulus (E′) is lowered in a silica-blended composition, the block rigidity of the tire tread is reduced to deteriorate the dry performance. A pneumatic tire in which a rubber composition obtained by blending a specific polymer and specific carbon black with silica is applied to a tread is reported as improving the wet performance, the abrasion resistance and the dry performance (Japanese Patent Application Laid-Open No. Hei 8-53002). In such case, however, the abrasion resistance has not necessarily been sufficiently improved since a material having a high glass transition temperature (Tg) is used as a rubber component.




Various silane coupling agents have been developed in order to solve these problems, but the dispersion of silica has not yet reached a sufficiently high level, and it has been particularly difficult to obtain the industrially good dispersion of silica.




Further, it is disclosed in Japanese Patent Publication No. Sho 63-2886 and Japanese Patent Application Laid-Open No. Hei 6-157825 to use hydrophobic precipitated silicic acid. However, there has been involved a drawback that since precipitated silicic acid subjected to complete hydrophobicity treatment is used, surface silanol groups which react with silane coupling agents disappear, and therefore rubber is not sufficiently reinforced.




On the other hand, it is disclosed in Japanese Patent Application Laid-Open No. Hei 3-197536 to try to improve the heat generating property by blending 100 parts by weight of at least one rubber selected from the group consisting of natural rubber and diene base synthetic rubber with 0.05 to 20 parts by weight of an alkylamine compound as well as 20 to 150 parts by weight of a reinforcing filler such as carbon black. However, it is neither disclosed nor suggested in the application described above that an improvement in the dispersibility of silica has been tried for a rubber composition blended with silica and that a heat generating property and an abrasion resistance have been improved in the rubber composition blended with silica.




Accordingly, an object of the present invention is to solve the above problems involved in conventional techniques and to provide a rubber composition in which the dispersibility of silica is improved and a Mooney viscosity is lowered and in which the low heat generating property and the abrasion resistance are improved.




Further, another object of the present invention is to provide a rubber composition which can improve the wet performance, the abrasion resistance and the dry performance of a tire with a good balance thereamong when applied to the tread of the tire.




DISCLOSURE OF THE INVENTION




The present inventors have done intensive researches on a silica-blended rubber composition in order to solve the problems described above and then have found that kneading a specific amount of a specific dispersion-improving agent into a prescribed amount of silica improves the dispersibility of silica in rubber to a large extent, lowers a Mooney viscosity of the rubber composition and provides the low heat generating property and the high abrasion resistance, and thus they have come to complete the present invention.




Further, the present inventors have done intensive researches on a silica-blended rubber composition in order to solve the problems described above and then have found that blending a prescribed amount of specific carbon black with a prescribed amount of silica and kneading a specific amount of a specific dispersion-improving agent into the blended silica improve the dispersibility of silica in rubber to a large extent, allow the efficient vulcanization to be carried out and provide a good wet performance, a good abrasion resistance and a good dry performance, and thus they have come to complete the present invention.




That is, according to one aspect of the present invention, there is provided a rubber composition prepared by blending 15 to 85 parts by weight of silica per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber and 1 to 15% by weight of a dispersion-improving agent based on the amount of silica.




In the constitution described above, effective as the dispersion-improving agent described above is any one compound selected from nitrogen-containing carbonyl compounds represented by any of the following Formulas (I) to (III):











wherein R represents hydrogen, a linear or branched and saturated or unsaturated aliphatic hydrocarbon having 1 to 20 carbon atoms, an aromatic hydrocarbon or an alicyclic hydrocarbon and may be the same or different;




an amine-modified silicone oil represented by the following Formula (IV):











wherein R


5


represents an alkyl group or a phenyl group; 1≦m+n≦200 and n/(m+n)≧0.15; X


1


represents an amino group or an N-substituted amino group represented by —R


1


NR


2


R


3


or —R


1


NHR


4


NR


2


R


3


; R


1


and R


4


represent —(CH


2


)


n


— (provided that n is 1, 2 or 3); R


2


and R


3


may be the same or different and represent a hydrogen atom, an alkyl group having 1 to 36 carbon atoms or a phenyl group; m and n represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




a fatty acid ester-modified silicone oil represented by the following Formula (V):











wherein R


6


represents an alkyl group or a phenyl group; 1≦p+q≦200 and q/(p+q)≧0.15; X


2


represents a fatty acid ester group represented by —OCOR


7


; R


7


represents an alkyl group or an alkenyl group each of which has 1 to 36 carbon atoms; p and q represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




an epoxy-modified silicone oil represented by the following Formula (VI):











wherein R


8


represents an alkyl group or a phenyl group; 1≦r+s≦200 and s/(r+s)≧0.15; X


3


represents an epoxy-containing group represented by











r and s represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




an alkoxy-modified silicone oil represented by the following Formula (VII):











wherein R


9


represents an alkyl group or a phenyl group; 1≦t+u≦200 and u/(t+u)≧0.15; X


4


represents an alkoxyl group; t and u represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




α,ω-dihydroxypolydimethylsiloxane represented by the following Formula (VIII):











Further, according to another aspect of the present invention, there is provided a rubber composition prepared by blending 20 to 60 parts by weight of silica and 30 to 80 parts by weight of carbon black which has a cetyl trimethylammonium bromide-adsorbing amount (CTAB) of 120 m


2


/g or more and a dibutyl phthalate-absorbing amount (DBP) of 120 ml/100 g or more, per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber, and 3 to 15% by weight of a dispersion-improving agent based on the amount of silica. The total amount of silica and carbon black is 50 to 120 parts by weight. In this case, effective as the dispersion-improving agent described above is any one compound selected from amine-modified silicone oils represented by the following Formula (IV):











wherein R


5


represents an alkyl group or a phenyl group; 1≦m+n≦200 and n/(m+n)≧0.15; X


1


represents an amino group or an N-substituted amino group represented by —R


1


NR


2


R


3


or —R


1


NHR


4


NR


2


R


3


; R


1


and R


4


represent —(CH


2


)


n


— (provided that n is 1, 2 or 3); R


2


and R


3


may be the same or different and represent a hydrogen atom, an alkyl group having 1 to 36 carbon atoms or a phenyl group; m and n represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




a fatty acid ester-modified silicone oil represented by the following Formula (V):











wherein R


6


represents an alkyl group or a phenyl group; 1≦p+q≦200 and q/(p+q)≧0.15; X


2


represents a fatty acid ester group represented by —OCOR


7


; R


7


represents an alkyl group or an alkenyl group each of which has 1 to 36 carbon atoms; p and q represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




an epoxy-modified silicone oil represented by the following Formula (VI):











wherein R


8


represents an alkyl group or a phenyl group; 1≦r+s≦200 and s/(r+s)≧0.15; X


3


represents an epoxy-containing group represented by











r and s represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




an alkoxy-modified silicone oil represented by the following Formula (VII):











wherein R


9


represents an alkyl group or a phenyl group; 1≦t+u≦200 and u/(t+u)≧0.15; X


4


represents an alkoxyl group; t and u represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure);




α,ω-dihydroxypolydimethylsiloxane represented by the following Formula (VIII):











and a hydrogen silicone oil represented by the following Formula (IX):











wherein R


10


represents an alkyl group or a phenyl group; 1≦v+w≦200 and w/(v+w)≧0.15; v and w represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).




BEST MODE FOR CARRYING OUT THE INVENTION




The embodiment of the present invention shall be explained below in detail.




Natural rubber (NR) or synthetic rubber can be used alone or in a blend thereof for the rubber component in the present invention. The synthetic rubber includes, for example, synthetic polyisoprene rubber (IR), polybutadiene rubber (BR) and styrene-butadiene rubber (SBR).




Silica used in the present invention includes, for example, precipitated silica comprising synthetic hydrated silicic acid. In particular, precipitated silica having a nitrogen-adsorbing specific surface area of 120 to 300 m


2


/g is effective.




The dispersion-improving agent used in the present invention includes solid ones and liquid ones. When the dispersion-improving agent is liquid, an inorganic filler on which 30% by weight or more of the dispersion-improving agent described above is carried in advance is preferably used such that the proportion of the dispersion-improving agent described above is controlled to 3 to 15% by weight based on the amount of silica. The inorganic filler on which the dispersion-improving agent is carried includes calcium carbonate, zinc oxide, mica, silica and carbon black, and silica and carbon black having a high carrying capacity for the dispersion-improving agent are preferred.




The blending amount of the dispersion-improving agent described above is 1 to 15% by weight, preferably 3 to 15% by weight based on the amount of silica. In the case that the above blending amount of the dispersion-improving agent is less than 1% by weight, a reduction in the Mooney viscosity of the rubber component and an improvement in the low heat generating property and the abrasion resistance can not be expected. On the other hand, in the case that it exceeds 15% by weight, an action as a plasticizer is exerted to a large extent, and the abrasion resistance is reduced. Accordingly, neither case is preferred.




In the present invention, a silane coupling agent is preferably used in combination with the dispersion-improving agent. This is to allow the silanol groups present on the surface of silica to couple with the polymer to form a reinforcing phase.




Preferred as a silane coupling agent is a compound represented by the following Formula (X) or (XI):






Y


3




1


—Si—C


b


H


2b


S


a


C


b


H


2b


Si—Y


3




1


or








Y


3




1


—SiC


b


H


2b


—X


5


  (X)






wherein X


5


represents a nitroso group, a mercapto group, a thiocyanate group, an amino group, an epoxy group, a vinyl group, a chlorine atom or an imide group; Y


1


represents an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a chlorine atom and may be the same or different; a represents an integer of 1 or more; and b represents an integer of 1 to 6:






Y


3




2


—SiC


b


H


2b


S


a


—X


6


  (XI)






wherein X


6


is represented by any of the following formulas:











Y


2


represents an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a chlorine atom and may be the same or different; a represents an integer of 1 or more; and b represents an integer of 1 to 6




To be specific, the silane coupling agent represented by Formula (X) includes bis(3-triethoxysilylpropyl)polysulfide, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane and γ-thiocyanatepropyltriethoxysilane, and the silane coupling agent represented by Formula (XI) includes 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, trimethoxysilylpropylmercaptobenzothiazole tetrasulfide, triethoxysilylpropylmethacrylate monosulfide and dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide.




The blending amount of the above silane coupling agent is 1 to 15% by weight, preferably 3 to 12% by weight based on the weight of silica. In the case that the blending amount of the silane coupling agent is less than 1% by weight, the coupling effect is small. On the other hand, in the case that it exceeds 15% by weight, the gelation of the polymer is caused. Accordingly, neither case is preferred.




Next, the first invention shall be explained.




The nitrogen-containing carbonyl compound used as one of the dispersion-improving agents in the present invention is at least one selected from the group consisting of the compounds represented by Formulas (I) to (III) described above, and they may be used alone or in combination of two or more kinds thereof.




The nitrogen-containing carbonyl compound used in the present invention has preferably a molecular weight of 250 or less. The specific examples thereof include urea, 1,1-dimethylurea, 1,3-dimethylurea, tetramethylurea, 1,3-diphenylurea and acetamide. When urea is used, the effect thereof is maximized, and therefore it is preferred.




The amine-modified silicone oil used as one of the dispersion-improving agents in the present invention is represented by Formula (IV) described above, wherein if the polymerization degree (m+n) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the low heat generating property is reduced as well. Accordingly, the polymerization degree (m+n) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [n/(m+n)] of the amino group or the N-substituted amino group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore n/(m+n) is preferably 0.15 or more, more preferably 0.3 or more. Further, the bonding form of the amine may be any of a primary amine, a secondary amine and a tertiary amine. When carbon black is used, a secondary amine and a tertiary amine are preferred, and a tertiary amine is more preferred. When it is used in combination with carbon black, hydrogen bonded to the nitrogen atom accelerates vulcanization reaction. Therefore, the scorch time is shortened, which is not preferred in terms of processing. In the formula, R


5


is preferably an alkyl group having 1 to 3 carbon atoms.




The fatty acid ester-modified silicone oil used as one of the dispersion-improving agents in the present invention is represented by Formula (V) described above, wherein if the polymerization degree (p+q) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the low heat generating property is reduced as well. Accordingly, the polymerization degree (p+q) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [q/(p+q)] of the fatty acid ester group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore q/(p+q) is preferably 0.15 or more, more preferably 0.3 or more. In the formula, R


6


is preferably an alkyl group having 1 to 3 carbon atoms.




The epoxy-modified silicone oil used as a dispersion-improving agent in the present invention is represented by Formula (VI) described above, wherein if the polymerization degree (r+s) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the low heat generating property is reduced as well. Accordingly, the polymerization degree (r+s) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [s/(r+s)] of the epoxy-containing group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore s/(r+s) is preferably 0.15 or more, more preferably 0.3 or more. In the formula, R


8


is preferably an alkyl group having 1 to 3 carbon atoms.




The alkoxy-modified silicone oil used as one of the dispersion-improving agents in the present invention is represented by Formula (VII) described above, wherein if the polymerization degree (t+u) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the low heat generating property is reduced as well. Accordingly, the polymerization degree (t+u) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [u/(t+u)] of the alkoxyl group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore u/(t+u) is preferably 0.15 or more, more preferably 0.3 or more. The preferred alkoxyl group is methoxyl, ethoxyl or propoxyl. In the formula, R


9


is preferably an alkyl group having 1 to 3 carbon atoms.




α,ω-Dihydroxypolydimethylsiloxane used as one of the dispersion-improving agents in the present invention is represented by Formula (VIII) described above, wherein if the polymerization degree g of the siloxane bond is larger than 80, the number per weight of the terminal silanol groups reacting with the silanol groups present on the surface of silica decreases, and the effects thereof can not be observed. Accordingly, the polymerization degree g of siloxane is preferably 1 to 80.




The blending amount of silica used in the present invention is 15 to 85 parts by weight, preferably 20 to 65 parts by weight per 100 parts by weight of the rubber component described above. In the case that the blending amount of silica is less than 15 parts by weight, the reinforcing property can not be obtained. On the other hand, in the case that it exceeds 85 parts by weight, the Mooney viscosity increases to deteriorate the workability such as warming extrusion. Accordingly, neither case is not preferred. The blending amount of silica is preferably 20 to 65 parts by weight in terms of the reinforcing property, the low heat generating property and the workability.




In the present invention, carbon black can further be used as a reinforcing filler. SAF, ISAF and HAF grades can preferably be used as carbon black used for the reinforcing filler in the present invention but carbon black shall not specifically be restricted to those carbon blacks mentioned above.




The blending amount of carbon black is preferably 20 to 80 parts by weight per 100 parts by weight of the rubber component described above. If the blending amount of carbon black exceeds 80 parts by weight, the high heat generating property is provided or the poor dispersion is caused to bring about a reduction in the processability in some case. On the other hand, if the blending amount is less than 20 parts by weight, the effect of blending carbon black is not observed so much. Accordingly, the blending amount is preferably 25 to 60 parts by weight in terms of the reinforcing property and the low heat generating property.




Next, the rubber composition according to another aspect of the present invention shall be explained in detail.




The amine-modified silicone oil used as one of the dispersion-improving agents in the present invention is represented by Formula (IV) described above, wherein if the polymerization degree (m+n) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the low heat generating property is reduced as well. Accordingly, the polymerization degree (m+n) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [n/(m+n)] of the amino group or the N-substituted amino group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore n/(m+n) is preferably 0.15 or more, more preferably 0.3 or more. Further, the bonding form of the amine may be any of a primary amine, a secondary amine and a tertiary amine. When carbon black is used, a secondary amine and a tertiary amine are preferred, and a tertiary amine is more preferred. When it is used in combination with carbon black, hydrogen bonded to the nitrogen atom accelerates vulcanization reaction. Therefore, the scorch time is shortened, which is not preferred in terms of processing. In the formula, R


5


is preferably an alkyl group having 1 to 3 carbon atoms.




The fatty acid ester-modified silicone oil used as one of the dispersion-improving agents in the present invention is represented by Formula (V) described above, wherein if the polymerization degree (p+q) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the heat generating property is reduced as well. Accordingly, the polymerization degree (p+q) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [q/(p+q)] of the fatty acid ester group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore q/(p+q) is preferably 0.15 or more, more preferably 0.3 or more. In the formula, R


6


is preferably an alkyl group having 1 to 3 carbon atoms.




The epoxy-modified silicone oil used as a dispersion-improving agent in the present invention is represented by Formula (VI) described above, wherein if the polymerization degree (r+s) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the heat generating property is reduced as well. Accordingly, the polymerization degree (r+s) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [s/(r+s)] of the epoxy-containing group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore s/(r+s) is preferably 0.15 or more, more preferably 0.3 or more. In the formula, R


8


is preferably an alkyl group having 1 to 3 carbon atoms.




The alkoxy-modified silicone oil used as one of the dispersion-improving agents in the present invention is represented by Formula (VII) described above, wherein if the polymerization degree (t+u) of the siloxane bond is larger than 200, the effect of lowering the Mooney viscosity of the rubber composition is reduced, and the effect of improving the heat generating property is reduced as well. Accordingly, the polymerization degree (t+u) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [u/(t+u)] of the alkoxyl group is smaller than 0.15, the aforementioned effects of the present invention can not be obtained sufficiently well, and therefore u/(t+u) is preferably 0.15 or more, more preferably 0.3 or more. The preferred alkoxyl group is methoxyl, ethoxyl or propoxyl. In the formula, R


9


is preferably an alkyl group having 1 to 3 carbon atoms.




α,ω-Dihydroxypolydimethylsiloxane used as one of the dispersion-improving agents in the present invention is represented by Formula (VIII) described above, wherein if the polymerization degree g of the siloxane bond is larger than 80, the number per weight of the terminal silanol groups reacting with the silanol groups present on the surface of silica decreases, and the effects thereof can not be observed. Accordingly, the polymerization degree g of siloxane is preferably 1 to 80.




The hydrogen silicone oil used as a dispersion-improving agent in the present invention is represented by Formula (IX) described above, wherein if the polymerization degree (v+w) of the siloxane bond grows larger, the Mooney viscosity of the rubber composition is elevated, and the effect of improving the low heat generating property is reduced. Accordingly, the polymerization degree (v+w) of the siloxane bond is preferably 1 to 200, more preferably 1 to 100. If the content [w/(v+w)] of the hydrogen is smaller than 0.15, the dispersibility of silica in the rubber can not be improved sufficiently well, and the efficient vulcanization can not be carried out sufficiently well. Accordingly, w/(v+w) is preferably 0.15 or more, more preferably 0.3 or more.




The blending amount of silica used in the present invention 20 to 60 parts by weight, preferably 20 to 50 parts by weight per 100 parts by weight of the rubber component described above. In the case that the blend amount of silica is less than 20 parts by weight, the wet performance is inferior. On the other hand, in the case that it exceeds 60 parts by weight, the workability such as warming extrusion is deteriorated in some case. Accordingly, neither case is preferred.




Carbon black used as a reinforcing filler in the present invention preferably has a cetyl trimethylammonium bromide-adsorbing amount (CTAB) of 120 m


2


/g or more and a dibutyl phthalate-absorbing amount (DBP)of 120 ml/100 g or more. If CTAB is less than 120 m


2


/g, the abrasion resistance tends to be reduced, and if DBP is less than 120 ml/100 g, the dry performance tends to be lowered. CTAB and DBP are values determined based on ASTM D3765-89 and JIS K6221, respectively.




The blending amount of carbon black is preferably 30 to 80 parts by weight, more preferably 30 to 60 parts by weight per 100 parts by weight of the rubber component described above. If this blending amount is less than 30 parts by weight, the dry performance tends to be lowered. On the other hand, if it exceeds 80 parts by weight, the Mooney viscosity of the rubber composition tends to be elevated, and the processability tends to be reduced.




Further, in the present invention, the total amount of silica and carbon black is preferably 50 to 120 parts by weight, more preferably 60 to 100 parts by weight per 100 parts by weight of the rubber component described above. If this total amount is less than 50 parts by weight, the wet performance, the dry performance and the abrasion resistance tend to be lowered. On the other hand, if it exceeds 120 parts by weight, the Mooney viscosity of the rubber composition tends to be elevated, and the processability tends to be reduced.




Presumed as follows is an action mechanism with respect to why the dispersibility of silica in the rubber is improved to a large extent and the heat generating property, the abrasion resistance and the dry performance are improved.




Usually, silica causes coagulation between silica grains by virtue of hydrogen bonds among silanol groups which are surface functional groups to bring about inferior dispersion in rubber. Further, there is a problem that since this silanol group is acidic, it has an action to adsorb a base material used as a vulcanization accelerator in vulcanizing the rubber composition and therefore the vulcanization would not be sufficiently carried out, so that the elastic modulus would not be increased.




Silane coupling agents usually used in the rubber industry reduce the amount of the silanol groups present on the surface of silica grains by dehydration condensation reaction of silanol groups on the surface of silica with silanol groups formed by the hydrolysis of alkoxyl groups to improve the dispersibility of silica in rubber. However, this reaction is difficult to take place at low a temperature and considered to go on at a temperature of 140° C. or higher. On the other hand, if the temperature is elevated to 170° C. or higher, a three dimensional cross-linking reaction of the rubber is brought about by a silane coupling agent, and the viscosity is drastically increased. Accordingly, the current situation is that the reaction time of silica with a silane coupling agent can not sufficiently be secured at an actual rubber-kneading step where the temperature of the kneaded rubber is rapidly elevated. However, the dispersion-improving agent used in the present invention does not cause the three dimensional cross-linking reaction of the rubber even at high temperatures, and therefore in order to prevent the three dimensional cross-linking reaction of the rubber, there can be used a method in which a kneading step is divided into multistage processing and in which temperature and time necessary for the reaction of silica with the active site of the dispersion-improving agent are sufficiently secured and then a silane coupling agent is added to be followed by kneading at a lower temperature.




As a result, in the rubber composition of the present invention, the dispersion of silica in the rubber is improved to a large extent and the Mooney viscosity of said rubber composition is reduced, and effective vulcanization is carried out. Accordingly, the heat generating property and the abrasion resistance are improved and further, the dry performance is improved as well since the dynamic storage elastic modulus goes up.




Here, the reaction of silica with the active site of the dispersion-improving agent means hydrogen-bonding between a nitrogen atom contained in the molecule and a silanol group present on the surface of silica in the case of the nitrogen-containing carbonyl compound and the amine-modified silicone oil, a dehydration condensation reaction of a silanol group formed by hydrolysis of the modified parts with a silanol group present on the surface of silica in the case of the fatty acid ester-modified silicone oil and the alkoxy-modified silicone oil, and a reaction of a silanol group present on the surface of silica with an epoxy group, a hydrogen atom directly bonded to a silicon atom in the main chain or a silanol group at the terminal in the cases of the epoxy-modified silicone oil, the hydrogen silicone oil or α,ω-dihydroxypolydimethylsiloxane, respectively. In particular, in the cases of the nitrogen-containing carbonyl compound and the amine-modified silicone oil, the hydrogen bond between the nitrogen atom contained in the molecule and the silanol group present on the surface of silica is not a primary bond but chemical adsorption, and therefore the effect of the dispersion improving agent is exhibited even in the range of room temperature. As a result, they have an effect of preventing silica grains from coagulating in the range of low temperatures at the beginning of kneading rubber.











EXAMPLES




The present invention shall specifically be explained below with reference to examples but the present invention shall not be restricted to the examples as long as the scope of the present invention is not exceeded.




Part and percentage shown in the examples are based on weight unless otherwise described.




Various measurements were carried out by the following methods.




1) Mooney viscosity




A Mooney viscosity ML 1+4 measured at 130° C. by a method according to JIS K6300 was used and shown by index in contrast with the control. The smaller the value of the index, the lower the Mooney viscosity and the better the processability.




2) Low heat generating property




An impact resilience modulus measured at a temperature of 25° C. according to JIS K6264-1993 was used and shown by index in contrast with the control. The smaller the value of the index, the higher the impact resilience modulus and the better the low heat generating property.




3) Abrasion resistance




An abrasion resistance index which shows an abrasion resistance was measured at a ground pressure of 0.5 Mpa and a slip rate of 40% by a method according to JIS K6255-1996 by means of a Lanbourn abrasion tester and calculated according to the following equation:






abrasion resistance index=(loss weight of control/loss weight of test piece)×100






It is shown that the larger this index is, the better the abrasion resistance is.




4) Dynamic storage elastic modulus (E′)




Measured on the conditions of a tensile dynamic distortion of 1%, a frequency of 50 Hz and a temperature of 60° C. by means of a visco-elasticity spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. A slab sheet having a thickness of about 2 mm and a width of 5 mm was used for the test piece, and set were a distance between the sample nippers to 2 cm and an initial load to 160 g. The value of E′ was shown by an index, wherein the value of a control was set at 100. The larger the value is, the higher the E′ is, and therefore the larger value is preferred.




5) Wet skid resistance




The wet skid resistance was obtained by measuring a slide resistance on a concrete road surface wetted with water at room temperature by means of a skid tester manufactured by Stanley London Co., Ltd., England. The evaluation thereof was shown by an index, wherein that of a control was set at 100. The larger the value is, the better the result is.




Rubber compositions for samples were prepared according to the recipe shown in Table 1. Shown respectively in the corresponding tables are the amounts of carbon black, silica and a silane coupling agent blended with the respective compositions, and the physical properties of the rubber compositions thus obtained.















TABLE 1











Blend component




Weight parts













Rubber component




100







Silica




Variable







Carbon black




Variable







Aromatic oil




Variable







Stearic acid




2







Silane coupling agent




Variable







Dispersion-improving agent




Variable







Zinc oxide




3







Antioxidant*


1






1







Vulcanization accelerator*


2






1.5







Sulfur




1.5













*


1


N-phenyl-N′-isopropyl-p-phenylenediamine











*


2


N-oxydiethylene-2-benzothiazole sulfenamide













Comparative Examples 1 to 13 and Examples 1 to 18




A nitrogen-containing carbonyl compound represented by any of Formulas (I) to (III) described above was used as a dispersion-improving agent.




Aromatic oil is blended in an amount of 20 parts by weight per 100 parts by weight of the rubber component in all compositions.




Experiment 1




Comparative Examples 1 to 6 and Examples 1 to 10




The physical properties of the resulting rubber compositions are shown in Table 2 and Table 3.

















TABLE 2













Comparative





Comparative








Example




Example




Example




Example




















1




2




1




2




3




3




4




5























Rubber component














NR




30




30




30




30




30




30




30




30






SBR1500*


1






70




70




70




70




70




70




70




70






BR01*


2








Silica*


3






60




60




60




60




60




60




60




60






Blend amount






Nitrogen-






containing compound






blend amount






Urea




 0




0.5




1.0




3.0




8.0




10.0 






1,1-dimethylurea










3.0






1,3-diphenylurea











3.0






Acetamide






Propionamide






Coupling agent






blend amount






Si69*


4






6.0




6.0




6.0




6.0




6.0




6.0




6.0




6.0






KBM803*


5








Mooney viscosity




100 




100 




95




81




85




111 




84




89






Low heat generating




100 




100 




95




84




79




78




90




92






property






Abrasion resistance




100 




100 




104 




121 




124 




120 




109 




109 











*


1


Emulsion-polymerized SBR manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


Polybutadiene manufactured by Japan Synthetic Rubber Co., Ltd.










*


3


Nipsil AQ manufactured by Nippon Silica Ind. Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


5


γ-Mercaptopropyltrimethoxysilane manufactured by Shin-etsu Chemical Ind. Co., Ltd.



























TABLE 3














Comparative





Comparative








Example




Example




Example




Example




Example




















6




7




8




4




5




9




6




10























Rubber component














NR




30




30




30




30




30




30






SBR1500*


1






70




70




70




70




70




70




70




70






BR01*


2












30




30






Silica*


3






60




60




80




90




60




60




60




60






Blend amount






Nitrogen-






containing compound






blend amount






Urea






4.5




4.5





3.0





3.0






1,1-dimethylurea






1,3-diphenylurea






Acetamide




3.0






Propionamide





3.0






Coupling agent






blend amount






Si69*


4






6.0




6.0




8.0




9.0




1.2




1.2




6.0




6.0






KBM803*


5








Mooney viscosity




86




91




99




128 




100 




78




100 




85






Low heat generating




92




93




97




114 




100 




87




100 




97






property






Abrasion resistance




107 




108 




131 




133 




100 




111 




100 




110 











*


1


Emulsion-polymerized SBR manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


Polybutadiene manufactured by Japan Synthetic Rubber Co., Ltd.










*


3


Nipsil AQ manufactured by Nippon Silica Ind. Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


5


γ-Mercaptopropyltrimethoxysilane manufactured by Shin-etsu Chemical Ind. Co., Ltd.













The Mooney viscosities, the low heat generating properties and the abrasion resistances are shown by indices with Comparative Example 1 being set as a control in Comparative Examples 1 to 4 and Examples 1 to 8, with Comparative Example 5 being set as a control in Comparative Example 5 and Example 9 and with Comparative Example 6 being set as a control in Comparative Example 6 and Example 10.




Commercial silica, Nipsil AQ (nitrogen-adsorbing specific surface area: 195 m


2


/g and oil absorbing amount: 190 ml/100 g) was used for silica in all examples and comparative examples.




In a system using bis(3-triethoxysilylpropyl) tetrasulfide (manufactured by Degussa AG.: hereinafter abbreviated as Si69) as a coupling agent, prepared in Comparative Example 1 was the rubber composition containing no nitrogen-containing carbonyl compound, and prepared in Comparative Examples 2 and 3 were the rubber compositions in which the amounts of the nitrogen-containing compound were deviated from the scope provided by the present invention.




It can be found that the processability and the low heat generating property can be improved at the same time by blending a specific amount of the carbonyl compound. Too much carbonyl compound causes scorch and therefore makes the processability inferior (Comparative Example 3).




Further, it can be found from Examples 4, 5, 6 and 7 that the effects remain unchanged even if the kind of the carbonyl compound is changed.




Comparative Example 4 and Example 8 are examples in which the amount of silica was changed. It can be found that too much amount of silica makes the low heat generating property inferior.




Comparative Example 5 and Example 9 are examples in which the kind of the coupling agent was changed, and Comparative Example 6 and Example 10 are examples in which the kind of the rubber was changed. It can be found that both the processability and the low heat generating property can be improved as well in these examples by blending the carbonyl compounds.




Experiment 2 (rubber compositions using carbon black in combination with silica)




Comparative Examples 7 to 10 and Examples 11 to 14




Rubber compositions for samples were prepared according to the recipe shown in Table 1. Shown in Table 4 are the amounts of carbon black, silica and the silane coupling agent blended with the respective compositions, and the physical properties of the rubber compositions thus obtained.



















TABLE 4













Comparative





Comparative





Comparative








Example




Example




Example




Example




Example




Example




















7




11




12




8




9




13




10




14























Rubber component














NR




30




30




30




30




30




30




30




30






SBR1500*


1






70




70




70




70




70




70




70




70






BR01*


2








Silica*


3






25




25




25




25




25




25




25




25






Blend amount






Carbon black






HAF*


4






50




50




70




105 






50




50






SAF*


5










50




50






Nitrogen-containing




 0




2.5




2.5




2.5




 0




2.5




 0




2.5






Compound blend amount






Urea






Coupling agent






Blend amount






Si69*


6






2.5




2.5




2.5




2.5




2.5




2.5






KBM803*


7












0.5




0.5






Mooney viscosity




100 




87




94




137 




100 




93




100 




94






Low heat generating




100 




88




94




152 




100 




95




100 




95






property






Abrasion resistance




100 




118 




127 




94




100 




110 




100 




109 











*


1


Emulsion-polymerized SBR manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


Polybutadiene manufactured by Japan Synthetic Rubber Co., Ltd.










*


3


Nipsil AQ manufactured by Nippon Silica Ind. Co., Ltd.










*


4


Seast 3H manufactured by Tokai Carbon Co., Ltd.










*


5


Seast 9 manufactured by Tokai Carbon Co., Ltd.










*


6


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


7


γ-Mercaptopropyltrimethoxysilane manufactured by Shin-etsu Chemical Ind. Co., Ltd.













The Mooney viscosities, the low heat generating property and the abrasion resistances are shown by indices with Comparative Example 7 being set as a control in Comparative Examples 7 and 8 and Examples 11 and 12, with Comparative Example 9 being set as a control in Comparative Example 9 and Example 13 and with Comparative Example 10 being set as a control in Comparative Example 10 and Example 14.




It can be found from Examples 11 and 12 and Comparative Example 8 that the effects remain unchanged even if the amount of carbon black is changed but too much amount thereof is not so good, and it can be found from Comparative Example 9 and Example 13 that the effects remain unchanged even if the kind of the carbon black is changed.




Further, it can be found from Comparative Example 10 and Example 14 that the effects remain unchanged even if the kind of the silane coupling agent is changed.




Experiment 3 (rubber compositions having a small blending amount of silica)




Comparative Examples 11 to 13 and Examples 15 to 18




Rubber compositions for samples were prepared according to the recipe shown in Table 1. Shown in Table 5 are the amounts of carbon black, silica and the silane coupling agent blended with the respective compositions, and the physical properties of the rubber compositions thus obtained.



















TABLE 5













Comparative





Comparative





Comparative








Example




Example




Example




Example




Example




Example



















11




15




16




12




17




13




18






















Rubber component













NR




30




30





30




30




30




30






SBR1500*


1






70




70




70




70




70




70




70






BR01*


2








30






Silica*


3






5.0




15




15




15




15




15




15






Blend amount






Nitrogen-containing




 0




1.5




1.5




 0




1.5




 0




1.5






Compound blend amount






Urea






Carbon black









45




45






HAF*


4








Coupling agent






blend amount






Si69*


5






0.5




1.5




1.5






1.5




1.5






KBM803*


6









0.3




0.3






Mooney viscosity




100 




100 




83




105 




97




100 




94






Low heat generating




100 




101 




92




108 




99




100 




93






property






Abrasion resistance




100 




151 




211 




147 




160 




100 




107 











*


1


Emulsion-polymerized SBR manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


Polybutadiene manufactured by Japan Synthetic Rubber Co., Ltd.










*


3


Nipsil AQ manufactured by Nippon Silica Ind. Co., Ltd.










*


4


Seast 3H manufactured by Tokai Carbon Co., Ltd.










*


5


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


6


γ-Mercaptopropyltrimethoxysilane manufactured by Shin-etsu Chemical Ind. Co., Ltd.













The Mooney viscosities, the low heat generating properties and the abrasion resistances are shown by indices with Comparative Example 11 being set as a control in Comparative Examples 11 and 12 and Examples 15 to 17 and with Comparative Example 13 being set as a control in Comparative Example 13 and Example 18.




It can be found from Comparative Examples 11 and 12 and Examples 15 to 17 that the low heat generating property can be improved by blending a specific amount of the carbonyl compound according to the present invention. Further, it can be found from Comparative Example 13 and Example 18 that the same effects can be obtained as well in a system using silica in combination with carbon black.




Comparative Examples 14 to 24 and Examples 19 to 32




Rubber compositions were prepared in the recipes shown in the following Tables 7 and 8 according to the basic recipe shown in Table 1 described previously. Various amine-modified silicon oils used for the above compositions are shown in the following Table 6.














TABLE 6






































m




n




m + n




n/(m + n)




Amino group




















Sample A




13




13




26




0.50




—(CH


2


)


3


NH


2








Sample B




59




33




92




0.36




—(CH


2


)


3


NH


2








Sample C




139 




193 




232 




0.40




—(CH


2


)


3


NH


2








Sample D




43




 6




49




0.12




—(CH


2


)


3


NH


2








Sample E




27




 6




33




0.18




—(CH


2


)


3


NH


2








Sample F




14




12




26




0.46




—(CH


2


)


3


NH(CH


2


)


2


NH


2















Sample G




12




14




26




0.54

























Sample H




10




12




22




0.55


























The rubber compositions obtained in the examples and the comparative examples were evaluated for a low heat generating property, an abrasion resistance and a Mooney viscosity.




In the evaluation, the rubber composition obtained in Comparative Example 14 was used as a control in Table 7. Further, used as controls respectively in Table 8 were the rubber composition obtained in Comparative Example 20 in a non-carbon-black-blended system and the rubber composition obtained in Comparative Example 23 in a carbon black-blended system.





















TABLE 7















Com-







Com-










parative







parative







Comparative





Exam-




Exam-




Comparative





Exam-




Exam-







Example




Example




ple




ple




Example




Example




ple




ple





























14




15




19




20




21




22




16




23




17




18




24




25




26




27




28




19




29
































Component























(parts by weight)






BR01*


1






—




—




—




—




—




—




—




—




—




—




—




—




—




—




—




—




20






SBR1500*


1






65




65




65




65




65




65




65




65




65




65




65




65




65




65




65




65




45






NR




35




35




35




35




35




35




35




35




35




35




35




35




35




35




35




35




35






Silica




60




60




60




60




54




60




60




60




60




60




60




60




60




60




80




90




60






(Nipsil AQ)*


2








Carbon black




—




—




—




—




—




—




—




—




—




—





—




—




—




—




—




—






(Seast 3H)*


3








Aromatic oil




20




19.5 




18




14




14




11




 8




14




14




14




14




14




14




14




 8




6.5




14






Silane coupling




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 8




 9




 6






agent Si69*


4








Amine-modified





0.5




 2




 6




 6




 9




12




 6




 6




 6




 6




 6




 6




 6




12




13.5 




 6






silicone oil




—




(A)




(A)




(A)




(A)*


5






(A)




(A)




(B)




(C)




(D)




(E)




(F)




(G)




(H)




(A)




(A)




(A)






(sample type)






Evaluation






Low heat




100 




100 




97




93




92




91




89




96




101 




98




9




93




92




91




97




102 




88






generating






property (index)






Abrasion




100 




98




102 




104 




103 




101 




98




106 




100 




97




102 




103 




104 




103 




121 




126 




113 






resistance






(index)






Mooney viscosity




100 




99




95




90




91




84




80




93




97




98




94




92




89




88




94




102 




92






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


5


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 12 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of an amine-modified silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the amine-modified silicone oil.



























TABLE 8













Comparative





Comparative





Comparative







Example




Example




Example




Example




Example




















20




21




22




30




23




31




32




24























Composition














(parts by weight)






NR




100 




100 




100 




100 




100 




100 




100 




100 






Silica




10




10




20




20




30




30




20




20






(Nipsil AQ)*


2








Carbon black




—




—




—




—




55




55




70




90






(Seast 3H)*


3








Aromatic oil




20




19




20




18




20




17




18




18






Silane coupling




 1




 1




 2




 2




 3




 3




 2




 2






agent Si69*


4








Amine-modified




—




1(A)




—




2(A)




—




3(A)




2(A)




2(A)






silicone oil






(sample type)






Evaluation






Low heat generating




100 




100 




103 




96




100 




95




98




105 






property (index)






Abrasion resistance




100 




99




106 




102 




100 




102 




122 




133 






(index)






Mooney viscosity




100 




99




105 




98




100 




94




98




108 






(index)














As apparent from the results shown in Table 7 and Table 8, the rubber compositions of the present invention blended with the amine-modified silicone oil are reduced in a Mooney viscosity and improved in a heat generating property and an abrasion resistance.




Comparative Examples 25 to 35 and Examples 33 to 45




Rubber compositions were prepared in the recipes shown in the following Tables 10 and 11 according to the basic recipe shown in Table 1 described previously. Various fatty acid ester-modified silicone oils used for the above compositions are shown in the following Table 9.














TABLE 9

















































q/








p




q




p + q




(p + q)




Fatty acid ester group




















Sam- ple A




17




21




38




0.55

























Sam- ple B




67




30




97




0.31

























Sam- ple C




150 




72




222 




0.32

























Sam- ple D




38




 5




43




0.12

























Sam- ple E




32




 7




39




0.18

























Sam- ple F




15




25




37




0.68

























Sam- ple G




14




25




39




0.64


























The rubber compositions obtained in the examples and the comparative examples were evaluated for a low heat generating property, an abrasion resistance and a Mooney viscosity.




In the evaluation, the rubber composition obtained in Comparative Example 25 was used as a control in Table 10. Further, used as controls respectively in Table 11 were the rubber composition obtained in Comparative Example 31 in a non-carbon-black-blended system and the rubber composition obtained in Comparative Example 34 in a carbon black-blended system.





















TABLE 10















Com-







Com-








Comparative





parative




Ex-




Comparative





parative




Ex-







Example




Example




Example




ample




Example




Example




Example




ample




























25




26




33




34




35




36




27




37




28




29




38




39




40




41




30




42































Composition






















(parts by weight)






BR01*


1






—




—




—




—




—




—




—




—




—




—




—




—




—




—




—




20






SBR1500*


1






65




65




65




65




65




65




65




65




65




65




65




65




65




65




65




45






NR




35




35




35




35




35




35




35




35




35




35




35




35




35




35




35




35






Silica




60




60




60




60




54




60




60




60




60




60




60




60




60




80




90




60






(Nipsil AQ)*


2








Carbon black




—




—




—




—




—




—




—




—




—




—




—




—




—




—




—




—






(Seast 3H)*


3








Aromatic oil




20




19.5 




18




14




14




11




 8




14




14




14




14




14




14




 8




6.5




14






Silane coupling




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 8




 9




 6






agent Si69*


4








Fatty acid ester-




—




0.5




 2




 6




 6




 9




12




 6




 6




 6




 6




 6




 6




12




13.5 




 6






modified silicone





(A)




(A)




(A)




(A)*


5






(A)




(A)




(B)




(C)




(D)




(E)




(F)




(G)




(A)




(A)




(A)






oil (sample type)






Evaluation






Low heat generating




100 




100 




94




92




92




89




87




96




100 




103 




96




90




94




96




107 




86






property (index)






Abrasion resistance




100 




102 




104 




105 




104 




104 




98




107 




101 




98




102 




106 




102 




124 




131 




118 






(index)






Mooney viscosity




100 




98




94




93




91




88




86




94




102 




98




96




92




95




95




112 




96






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


5


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 12 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of an fatty acid ester-modified silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the fatty acid ester-modified silicone oil.



























TABLE 11













Comparative





Comparative





Comparative







Example




Example




Example




Example




Example




















31




32




33




43




34




44




45




35























Composition














(parts by weight)






NR




100 




100 




100 




100 




100 




100 




100 




100 






Silica




10




10




20




20




30




30




20




20






(Nipsil AQ)*


2








Carbon black




—




—




—




—




55




55




70




90






(Seast 3H)*


3








Aromatic oil




20




19




20




18




20




17




18




18






Silane coupling




 1




 1




 2




 2




 3




 3




 2




 2






agent Si69*


4








Fatty acid ester-




—




1(A)




—




2(A)




—




3(A)




2(A)




2(A)






modified silicone






oil (sample type)






Evaluation






Low heat generating




100 




98




106 




99




100 




93




98




108 






property (index)






Abrasion resistance




100 




99




112 




114 




100 




104 




125 




134 






(index)






Mooney viscosity




100 




100 




104 




98




100 




94




99




109 






(index)














As apparent from the results shown in Table 10 and Table 11, the rubber compositions of the present invention blended with the fatty acid ester-modified silicone oil are reduced in a Mooney viscosity and improved in a heat generating property and an abrasion resistance.




Comparative Examples 36 to 46 and Examples 46 to 56




Rubber compositions were prepared in the recipes shown in the following Tables 13 and 14 according to the basic recipe shown in Table 1 described previously. Various epoxy-modified silicone oils used for the above compositions are shown in the following Table 12.














TABLE 12






































r




s




r + s




s/(r + s)




Epoxy group




















Sample A




21




14




35




0.40

























Sample B




46




52




98




0.53

























Sample C




116 




107 




213 




0.50

























Sample D




24




 4




28




0.14

























Sample E




13




17




30




0.57


























The rubber compositions obtained in the examples and the comparative examples were evaluated for a low heat generating property, an abrasion resistance and a Mooney viscosity.




In the evaluation, the rubber composition obtained in Comparative Example 36 was used as a control in Table 13. Further, used as controls respectively in Table 14 were the rubber composition obtained in Comparative Example 42 in a non-carbon-black-blended system and the rubber composition obtained in Comparative Example 45 in a carbon-black-blended system.





















TABLE 13















Com-







Com-








Comparative





parative




Ex-




Comparative





parative




Ex-







Example




Example




Example




ample




Example




Example




Example




ample


























36




37




46




47




48




49




38




50




39




40




51




52




41




53





























Component




















(parts by weight)






BR01*


1






—




—




—




—




—




—




—




—




—




—




—




—




—




20






SBR1500*


1






65




65




65




65




65




65




65




65




65




65




65




65




65




45






NR




35




35




35




35




35




35




35




35




35




35




35




35




35




35






Silica




60




60




60




60




54




60




60




60




60




60




60




80




90




60






(Nipsil AQ)*


2








Carbon black






(Seast 3H)*


3






—




—




—




—




—




—




—




—




—




—




—




—




—






Aromatic oil




20




19.5 




18




14




14




11




 8




14




14




14




14




 8




6.5




14






Silane coupling




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 8




 9




 6






agent Si69*


4








Epoxy-modified




—




0.5




 2




 6




 6




 9




12




 6




 6




 6




 6




12




13.5 




 6






silicone oil





(A)




(A)




(A)




(A)*


5






(A)




(A)




(B)




(C)




(D)




(E)




(A)




(A)




(A)






(sample type)






Evaluation






Low heat generating




100 




99




96




91




90




87




85




94




102 




100 




93




96




104 




86






property (index)






Abrasion resistance






(index)




100 




98




101 




105 




104 




103 




100 




106 




101 




99




104 




118 




125 




116 






Mooney viscosity




100 




100 




94




89




90




85




78




94




95




92




92




98




104 




94






(index)











*


1: manufactured by Japan Synthetic Rubber Co., Ltd.












*


2: manufactured by Nippon Silica Ind. Co., Ltd.












*


3: manufactured by Tokai Carbon Co., Ltd.












*


4: Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.












*


5: Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 12 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of an epoxy-modified silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the epoxy-modified silicone oil.





























TABLE 14













Comparative





Comparative





Comparative







Example




Example




Example




Example




Example




















42




43




44




54




45




55




56




46























Composition














(parts by weight






NR




100 




100 




100 




100 




100 




100 




100 




100 






Silica




10




10




20




20




30




30




20




20






(Nipsil AQ)*


2








Carbon black




—




—




—




—




55




55




70




90






(Seast 3H)*


3








Aromatic oil




20




19




20




18




20




17




18




18






Silane coupling




 1




 1




 2




 2




 3




 3




 2




 2






agent Si69*


4








Fatty ester-modified




—




1(A)




—




2(A)




—




3(A)




2(A)




2(A)






silicone oil






(sample type)






Evaluation






Low heat generating




100 




100 




102 




97




100 




92




98




108 






property (index)






Abrasion resistance




100 




98




109 




112 




100 




104 




129 




138 






(index)






Mooney viscosity




100 




98




104 




96




100 




91




97




112 






(index)














As apparent from the results shown in Table 13 and Table 14, the rubber compositions of the present invention blended with the epoxy-modified silicone oil are reduced in a Mooney viscosity and improved in a heat generating property and an abrasion resistance.




Comparative Examples 47 to 57 and Examples 57 to 69




Rubber compositions were prepared in the recipes shown in the following Tables 16 and 17 according to the basic recipe shown in Table 1 described previously. Various alkoxyl-modified silicone oils used for the above compositions are shown in the following Table 15.














TABLE 15






































t




u




t + u




u/(t + u)




Alkoxyl group




















Sample A




12




14




26




0.54




—OC


2


H


5








Sample B




58




35




93




0.38




—OC


2


H


5








Sample C




152 




53




205 




0.26




—OC


2


H


5








Sample D




48




 7




55




0.13




—OC


2


H


5








Sample E




24




 5




29




0.17




—OC


2


H


5








Sample F




15




15




30




0.50




—OCH


3








Sample G




12




18




30




0.60




—OC


3


H


7
















The rubber compositions obtained in the examples and the comparative examples were evaluated for a low heat generating property, an abrasion resistance and a Mooney viscosity.




In the evaluation, the rubber composition obtained in Comparative Example 47 was used as a control in Table 16. Further, used as controls respectively in Table 17 were the rubber composition obtained in Comparative Example 53 in a non-carbon-black-blended system and the rubber composition obtained in Comparative Example 56 in a carbon-black-blended system.





















TABLE 16















Com-





Com-










Comparative





parative




Ex-




parative





parative




Ex-







Example




Example




Example




ample




Example




Example




Example




ample




























47




48




57




58




59




60




49




61




50




51




62




63




64




65




52




66































Composition






















(parts by weight)






BR01*


1






—




—




—




—




—




—




—




—




—




—




—




—




—




—




—




20






SBR1500*


1






65




65




65




65




65




65




65




65




65




65




65




65




65




65




65




45






NR




35




35




35




35




35




35




35




35




35




35




35




35




35




35




35




35






Silica




60




60




60




60




54




60




60




60




60




60




60




60




60




80




90




60






(Nipsil AQ)*


2








Carbon black




—




—




—




—




—




—




—




—




—




—




—




—




—




—




—




—






(Seast 3H)*


3








Aromatic oil




20




19.5 




18




14




14




11




 8




14




14




14




14




14




14




 8




6.5




14






Silane coupling




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 6




 8




 9




 6






agent Si69*


4








Alkoxyl-modified




—




0.5




 2




 6




 6




 9




12




 6




 6




 6




 6




 6




 6




12




13.5 




 6






silicone oil





(A)




(A)




(A)




(A)*


5






(A)




(A)




(B)




(C)




(D)




(E)




(F)




(G)




(A)




(A)




(A)






(sample type)






Evaluation






Low heat generating




100 




100 




96




90




91




88




86




94




101 




102 




97




88




94




97




104 




88






property (index)






Abrasion resistance




100 




99




102 




104 




104 




102 




98




107 




98




94




102 




102 




103 




114 




122 




115 






(index)






Mooney viscosity




100 




96




95




92




91




87




84




96




98




94




98




86




95




96




105 




90






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


5


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 12 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of an alkoxyl-modified silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the alkoxyl-modified silicone oil.



























TABLE 17













Comparative





Comparative





Comparative







Example




Example




Example




Example




Example




















53




54




55




67




56




68




69




57























Composition














(parts by weight)






NR




100 




100 




100 




100 




100 




100 




100 




100 






Silica






(Nipsil AQ)*


2






10




10




20




20




30




30




20




20






Carbon black




—




—




—




—




55




55




70




90






(Seast 3H)*


3








Aromatic oil




20




19




20




18




20




17




18




18






Silane coupling




 1




 1




 2




 2




 3




 3




 2




 2






agent Si69*


4








Alkoxyl-modified




—




1(A)




—




2(A)




—




3(A)




2(A)




2(A)






silicone oil






(sample type)






Evaluation






Low heat generating




100 




100 




105 




98




100 




92




99




107 






property (index)






Abrasion resistance




100 




98




115 




116 




100 




102 




128 




136 






(index)






Mooney viscosity




100 




96




104 




97




100 




91




96




112 






(index)














As apparent from the results shown in Table 16 and Table 17, the rubber compositions of the present invention blended with the alkoxyl-modified silicone oil are reduced in a Mooney viscosity and improved in a heat generating property and an abrasion resistance according to the present invention as has so far been explained above.




Comparative Examples 58 to 67 and Examples 70 to 80




Rubber compositions were prepared in the recipes shown in the following Tables 19 and 20 according to the basic recipe shown in Table 1 described previously. Various α,ω-dihydroxypolydimethylsiloxanes used for the above compositions are shown in the following Table 18.












TABLE 18
































g


















Sample A




10







Sample B




40







Sample C




70







Sample D




120 















The rubber compositions obtained in the examples and the comparative examples were evaluated for a low heat generating property, an abrasion resistance and a Mooney viscosity.




In the evaluation, the rubber composition obtained in Comparative Example 58 was used as a control in Table 19. Further, used as controls respectively in Table 20 were the rubber composition obtained in Comparative Example 63 in a non-carbon-black-blended system and the rubber composition obtained in Comparative Example 66 in a carbon-black-blended system.
















TABLE 19















Com-









parative







Comparative





Ex-







Example




Example




ample



















58




59




70




71




72




73




60









Composition






(parts by weight)






BR01*


1






—




—




—




—




—




—




—






SBR1500*


1






65




65




65




65




65




65




65






NR




35




35




35




35




35




35




35






Silica




60




60




60




60




54




60




60






(Nipsil AQ)*


2








Carbon black




—




—




—




—




—




—




—






(Seast 3H)*


3








Aromatic oil




20




19.5 




18




14




14




11




 8






Silane coupling




 6




 6




 6




 6




 6




 6




 6






agent Si69*


4








α,ω-dihydroxy-




—




0.5




 2




 6




 6




 9




12






polydimethyl-





(A)




(A)




(A)




(A)*


5






(A)




(A)






siloxane






(sample type)






Evaluation






Low heat generating




100 




100 




94




88




86




84




84






property (index)






Abrasion resistance




100 




100 




104 




106 




107 




103 




98






(index)






Mooney viscosity




100 




98




94




90




88




85




82






(index)





















Com-





Com-









parative





parative








Ex-




Ex-




Ex-




Ex-







Example




ample




ample




ample




ample


















74




75




61




76




62




77









Composition






(parts by weight)






BR01*


1






—




—




—




—




—




20






SBR1500*


1






65




65




65




65




65




45






NR




35




35




35




35




35




35






Silica




60




60




60




80




90




60






(Nipsil AQ)*


2








Carbon black




—




—




—




—




—




—






(Seast 3H)*


3








Aromatic oil




14




14




14




 8




6.5




14






Silane coupling




 6




 6




 6




 8




 9




 6






agent Si69*


4








α,ω-dihydroxypoly-




 6




 6




 6




12




13.5




 6






dimethylsiloxane




(B)




(C)




(D)




(A)




(A)




(A)






(sample type)






Evaluation






Low heat generating




94




96




102 




96




105 




85






property (index)






Abrasion resistance




104 




102 




98




116 




118 




112 






(index)






Mooney viscosity




93




95




98




95




107 




92






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.










*


5


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 12 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of α,ω-dihydroxypolydimethylsiloxane was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying α,ω-dihydroxypolydimethylsiloxane.



























TABLE 20













Comparative





Comparative





Comparative







Example




Example




Example




Example




Example




















63




64




65




78




66




79




80




67























Composition














(parts by weight)






NR




100 




100 




100 




100 




100 




100 




100 




100 






Silica




10




10




20




20




30




30




20




20






(Nipsil AQ)*


2








Carbon black




—




—




—




—




55




55




70




90






(Seast 3H)*


3








Aromatic oil




20




19




20




18




20




17




18




18






Silane coupling




 1




 1




 2




 2




 3




 3




 2




 2






agent Si69*


4








αω-dihydroxy-




—




1(A)




—




2(A)




—




3(A)




2(A)




2(A)






polydimethyl-






siloxane






(sample type)






Evaluation






Low heat generating




100 




99




104 




97




100 




94




98




106 






property (index)






Abrasion resistance




100 




98




116 




118 




100 




102 




124 




130 






(index)






Mooney viscosity




100 




96




103 




96




100 




92




98




111 






(index)














As apparent from the results shown in Table 19 and Table 20, the rubber compositions of the present invention blended with α,ω-dihydroxypolydimethylsiloxane are reduced in a Mooney viscosity and improved in a heat generating property and an abrasion resistance according to the present invention as has so far been explained above.




Comparative Examples 68 to 77 and Examples 81 to 93




Rubber compositions were prepared in the recipes shown in the following Tables 23 and 24 according to the basic recipe shown in Table 1 described previously. Shown respectively are various carbon blacks in Table 21 and various alkoxyl-modified silicone oils in the following Table 22 each of which is used for the above compositions.














TABLE 21













Type of carbon black*
















N134




N234




N220




N125





















CTAB (m


2


/g)




134




120




110




126







DBP (ml/100 g)




127




125




114




104













*manufactured by Asahi Carbon Co., Ltd.























TABLE 22





































t




u




t + u




u/(t + u)



















Sample A




24




 5




29




0.17






Sample B




15




15




30




0.50






Sample C




58




35




93




0.38






Sample D




152 




53




205 




0.26






Sample E




48




 7




55




0.13














The rubber compositions obtained in the examples and the comparative examples were evaluated for a dynamic storage elastic modulus (E′), an abrasion resistance and a wet skid resistance by the evaluation methods described previously.

















TABLE 23













Comparative





Comparative




Ex-







Example




Example




Example




ample



















68




69




81




82




70




71




83









Composition






(parts by weight)






NR




—




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




60




30




30




30




30




25






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




—




30




30




30




30




30






Type




N134




—




N134




N134




N134




N134




N134






Silane coupling




1.5




 3




1.5




1.5




1.5




1.5




 1.25






agent Si69*


4








Alkoxyl-modified






silicone oil






A




—




—




1.5




1.5




1.5




1.5




2.5






B




—




—




—




—




—




—




—






C




—




—




—




—




—




—




—






D




—




—




—




—




—




—




—






E




—




—




—




—




—




—




—






Evaluation






E′ (index)




100 




87




112 




106 




95




98




108 






Abrasion resistance




100 




84




109 




105 




96




104 




106 






(index)






Wet skid resistance




100 




118 




104 




102 




96




97




102 






(index)




















Com-





Com-





Com-







parative





parative





parative







Ex-





Ex-




Ex-




Ex-







ample




Example




ample




ample




ample


















72




84




85




73




86




74









Composition






(parts by weight)






NR




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




15




20




20




30




60




70






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




80




80




100 




20




10






Type




N134




N134




N134




N134




N134




N134






Silane coupling




 0.75




1.0




1.0




1.5




3.0




3.5






agent Si69*


4








Alkoxyl-modified






silicone oil






A




1.5




2.0




2.0




3.0




6.0




8.0






B




—




—




—




—




—




—






C




—




—




—




—




—




—






D




—




—




—




—




—




—






E




—




—




—




—




—




—






Evaluation






E′ (index)




104 




120 




114 




137 




100 




101 






Abrasion resistance




99




124 




118 




91




104 




94






(index)






Wet skid resistance




95




105 




102 




106 




120 




126 






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.













In the comparative examples, the Mooney viscosities are high, and therefore the kneaded rubbers have very bad surfaces. Further, they are inferior in the dispersibility of carbon black and therefore reduced also in an abrasion resistance.
















TABLE 24














Comparative








Example




Example




Example


















87




88




75




76




89




90









Composition






(parts by weight)






NR




—




—




—




—




—




—






0120*


5






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




30




30




30




30




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




30




30






Type




N134




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




1.5




1.5




1.5






agent Si69






Alkoxyl-modified






silicone oil






A




3.0




 6




 8




0.6




—




—






B




—




—




—




—




3.0






C




—




—




—




—




—






D




—




—




—




—




—






E




—




—




—




—




—






Evaluation






E′ (index)




114 




105 




102 




101 




114 




110 






Abrasion resistance




106 




103 




96




97




108 




106 






(index)






Wet skid resistance




103 




103 




102 




100 




102 




101 






(index)

















Comparative








Example




Example

















77




78




91




92




93









Composition






(parts by weight)






NR




—




—




40




—




—






0120*


5






94.5 




94.5 




81




94.5 




94.5 






BR01




30




30




—




30




30






Aromatic oil




5.5




5.5




 9




5.5




5.5






Silica




30




30




30




27




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




27






Type




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




—




—






agent Si69






Alkoxyl-modified






silicone oil






A




—




—




3.0




 


 


3.0*


6






 


 


3.0*


7








B




—




—




—




—






C




3.0




—




—




—






D




—




3.0




—




—






E




—




—




3.0




—






Evaluation






E′ (index)




105 




102 




115 




115 




114 






Abrasion resistance




98




96




102 




105 




106 






(index)






Wet skid resistance




101 




100 




102 




104 




104 






(index)











*


5


Emulsion-polymerized styrene-butadiene rubber having a styrene content of 35% (oil-extended with aromatic oil of 37.5 parts by weight).










*


6


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.










*


7


Silica obtained by carrying Sample A on N134 in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of carbon black (N134) was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.













Comparative Examples 78 to 88 and Examples 94 to 105




Rubber compositions were prepared in the recipes shown in the following Tables 26 and 27 according to the basic recipe shown in Table 1 described previously. Shown respectively are various carbon blacks in Table 21 and various epoxy-modified silicone oils in the following Table 25 each of which is used for the above compositions.














TABLE 25





































r




s




r + s




s/(r + s)



















Sample A




21




14




35




0.40






Sample B




46




52




98




0.53






Sample C




116 




107 




213 




0.50






Sample D




24




 4




28




0.14














The rubber compositions obtained in the examples and the comparative examples were evaluated for a dynamic storage elastic modulus (E′), an abrasion resistance and a wet skid resistance by the evaluation methods described previously.

















TABLE 26













Comparative





Comparative




Ex-







Example




Example




Example




ample



















78




79




94




95




80




81




96









Composition






(parts by weight)






NR




—




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


l






30




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




60




30




30




30




30




25






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




—




30




30




30




30




30






Type




N134




—




N134




N134




N134




N134




N134






Silane coupling




1.5




 3




1.5




1.5




1.5




1.5




 1.25






agent Si69*


4








Epoxy-modified






silicone oil






A




—




—




1.5




1.5




1.5




1.5




2.5






B




—




—




—




—




—




—




—






C




—




—




—




—




—




—




—






D




—




—




—




—




—




—




—






Evaluation






E′ (index)




100 




87




106 




102 




94




95




106 






Abrasion resistance




100 




84




106 




102 




96




101 




105 






(index)






Wet skid resistance




100 




118 




102 




100 




96




97




102 






(index)




















Com-





Com-





Com-







parative





parative





parative







Ex-





Ex-




Ex-




Ex-







ample




Example




ample




ample




ample


















82




97




98




83




99




84









Composition






(parts by weight)






NR




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


l






30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




15




20




20




30




60




70






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




80




80




100 




20




10






Type




N134




N134




N134




N134




N134




N134






Silane coupling




 0.75




1.0




1.0




1.5




3.0




3.5






agent Si69*


4








Epoxy-modified






silicone oil






A




1.5




2.0




2.0




3.0




6.0




8.0






B




—




—




—




—




—




—






C




—




—




—




—




—




—






D




—




—




—




—




—




—






Evaluation






E′ (index)




102 




118 




110 




138 




105 




108 






Abrasion resistance




98




122 




108 




92




104 




94






(index)






Wet skid resistance




98




103 




101 




106 




118 




124 






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.













In the comparative examples, the Mooney viscosities are high, and therefore the kneaded rubbers have very bad surfaces. Further, they are inferior in the dispersibility of carbon black and therefore reduced also in an abrasion resistance.
















TABLE 27














Comparative








Example




Example




Example

















100




101




85




86




102









Composition






(parts by weight)






NR




—




—




—




—




—






0120*


5






94.5 




94.5 




94.5 




94.5 




94.5 






BR01




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5






Silica




30




30




30




30




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




30






Type




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




1.5




1.5






agent Si69






Epoxy-modified






silicone oil






A




3.0




 6




 8




0.6




—






B




—




—




—




—




3.0






C




—




—




—




—




—






D




—




—




—




—




—






Evaluation






E′ (index)




110 




106 




101 




98




112 






Abrasion resistance




105 




102 




97




95




104 






(index)






Wet skid resistance




101 




101 




100 




99




102 






(index)

















Comparative








Example




Example

















87




88




103




104




105









Composition






(parts by weight)






NR




—




—




40




—




—






0120*


5






94.5 




94.5 




81




94.5 




94.5 






BR01




30




30




—




30




30






Aromatic oil




5.5




5.5




 9




5.5




5.5






Silica




30




30




30




27




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




27






Type




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




—




—






agent Si69






Alkoxyl-modified






silicone oil






A




—




—




3.0




 


 


3.0*


6






 


 


3.0*


7








B




3.0




—




—




—




—






C




—




3.0




—




—






D




—




—




3.0




—






Evaluation






E′ (index)




104 




102 




110 




108 




109 






Abrasion resistance




94




94




102 




104 




104 






(index)






Wet skid resistance




102 




100 




103 




103 




102 






(index)











*


5


Emulsion-polymerized styrene-butadiene rubber having a styrene content of 35% (oil-extended with aromatic oil of 37.5 parts by weight).










*


6


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.










*


7


Silica obtained by carrying Sample A on N134 in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of carbon black (N134) was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.













Comparative Examples 89 to 99 and Examples 106 to 118




Rubber compositions were prepared in the recipes shown in the following Tables 29 and 30 according to the basic recipe shown in Table 1 described previously. Shown respectively are various carbon blacks in Table 21 and various amine-modified silicone oils in the following Table 28 each of which is used for the above compositions.














TABLE 28





































m




n




m + n




n/(m + n)



















Sample A




27




 6




33




0.18






Sample B




13




13




26




0.50






Sample C




59




33




92




0.36






Sample D




139 




93




232 




0.40






Sample E




43




 6




49




0.12














The rubber compositions obtained in the examples and the comparative examples were evaluated for a dynamic storage elastic modulus (E′), an abrasion resistance and a wet skid resistance by the evaluation methods described previously.

















TABLE 29













Comparative





Comparative




Ex-







Example




Example




Example




ample



















89




90




106




107




91




92




108









Composition






(parts by weight)






NR




—




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




60




30




30




30




30




25






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




—




30




30




30




30




30






Type




N134




—




N134




N134




N134




N134




N134






Silane coupling




1.5




 3




1.5




1.5




1.5




1.5




1.25






agent Si69*


4








Amine-modified






silicone oil






A




—




—




1.5




1.5




1.5




1.5




2.5






B




—




—




—




—




—




—




—






C




—




—




—




—




—




—




—






D




—




—




—




—




—




—




—






E




—




—




—




—




—




—




—






Evaluation






E′ (index)




100 




87




108 




103 




94




97




107 






Abrasion resistance




100 




84




106 




102 




94




102 




104 






(index)






Wet skid resistance




100 




118 




102 




100 




96




98




103 






(index)




















Com-





Com-





Com-







parative





parative





parative







Ex-





Ex-




Ex-




Ex-







ample




Example




ample




ample




ample


















93




109




110




94




111




95









Composition






(parts by weight)






NR






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




15




20




20




30




60




70






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




80




80




100 




20




10






Type




N134




N134




N134




N134




N134




N134






Silane coupling




0.75




1.0




1.0




1.5




3.0




3.5






agent Si69*


4








Amine-modified






silicone oil






A




1.5




2.0




2.0




3.0




6.0




8.0






B




—




—




—




—




—




—






C




—




—




—




—




—




—






D




—




—




—




—




—




—






E




—




—




—




—




—




—






Evaluation






E′ (index)




100 




120 




112 




134 




107 




109 






Abrasion resistance




94




126 




116 




91




106 




92






(index)






Wet skid resistance




101 




102 




102 




104 




121 




126 






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.













In the comparative examples, the Mooney viscosities are high, and therefore the kneaded rubbers have very bad surfaces. Further, they are inferior in the dispersibility of carbon black and therefore reduced also in an abrasion resistance.
















TABLE 30














Comparative








Example




Example




Example


















112




113




96




97




114




115









Composition






(parts by weight)






NR




—




—




—




—




—




—






0120*


5






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




30




30




30




30




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




30




30






Type




N134




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




1.5




1.5




1.5






agent Si69






Amine-modified






silicone oil






A




3.0




 6




 8




0.6




—




—






B




—




—




—




—




3.0




—






C




—




—




—




—




—




3.0






D




—




—




—




—




—




—






E




—




—




—




—




—




—






Evaluation






E′ (index)




112 




104 




102 




99




114 




111 






Abrasion resistance




104 




102 




95




95




106 




104 






(index)






Wet skid resistance




102 




102 




101 




100 




103 




102 






(index)

















Comparative








Example




Example

















98




99




116




117




118









Composition






(parts by weight)






NR




—




—




40




—




—






0120*


5






94.5 




94.5 




81




94.5 




94.5 






BR01




30




30




—




30




30






Aromatic oil




5.5




5.5




 9




5.5




5.5






Silica




30




30




30




27




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




27






Type




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




—




—






agent Si69






Amine-modified






agent Si69






A




—




—




3.0






 


 3.0*


6








 


 3.0*


7








B




—




—




—




—






C




—




—




—




—






D




3.0




—




—




—






E




—




3.0




—




—






Evaluation






E′ (index)




106 




101 




115 




114 




112 






Abrasion resistance




96




95




102 




106 




106 






(index)






Wet skid resistance




100 




102 




102 




103 




102 






(index)











*


5


Emulsion-polymerized styrene-butadiene rubber having a styrene content of 35% (oil-extended with aromatic oil of 37.5 parts by weigh).










*


6


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.










*


7


Silica obtained by carrying Sample A on N134 in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of carbon black (N134) was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.













Comparative Examples 100 to 110 and Examples 119 to 131




Rubber compositions were prepared in the recipes shown in the following Tables 32 and 33 according to the basic recipe shown in Table 1 described previously. Shown respectively are various carbon blacks in Table 21 and various fatty acid ester-modified silicone oils in the following Table 31 each of which is used for the above compositions.














TABLE 31





































p




q




p + q




q/(p + q)



















Sample A




32




 7




39




0.18






Sample B




17




21




38




0.55






Sample C




67




30




97




0.31






Sample D




150 




72




222 




0.32






Sample E




38




 5




43




0.12














The rubber compositions obtained in the examples and the comparative examples were evaluated for a dynamic storage elastic modulus (E′), an abrasion resistance and a wet skid resistance by the evaluation methods described previously.

















TABLE 32













Comparative





Comparative




Ex-







Example




Example




Example




ample



















100




101




119




120




102




103




121









Composition






(parts by weight)






NR




—




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




60




30




30




30




30




25






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




—




30




30




30




30




30






Type




N134




—




N134




N134




N134




N134




N134






Silane coupling




1.5




 3




1.5




1.5




1.5




1.5




1.25






agent Si69*


4








Fatty acid






ester-modified






silicone oil






A




—




—




1.5




1.5




1.5




1.5




2.5






B




—




—




—




—




—




—




—






C




—




—




—




—




—




—




—






D




—




—




—




—




—




—




—






E




—




—




—




—




—




—




—






Evaluation






E′ (index)




100 




87




110 




105 




96




98




106 






Abrasion resistance




100 




84




107 




102 




95




103 




103 






(index)






Wet skid resistance




100 




118 




105 




102 




93




96




103 






(index)




















Com-





Com-





Com-







parative





parative





parative







Ex-





Ex-




Ex-




Ex-







ample




Example




ample




ample




ample


















104




122




123




105




124




106









NR




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




15




20




20




30




60




70






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




80




80




100 




20




10






Type




N134




N134




N134




N134




N134




N134






Silane coupling




0.75




1.0




1.0




1.5




3.0




3.5






agent Si69*


4








Fatty acid






ester-modified






silicone oil






A




1.5




2.0




2.0




3.0




6.0




8.0






B




—




—




—




—




—




—






C




—




—




—




—




—




—






D




—




—




—




—




—




—






Evaluation




—




—




—




—




—




—






E′ (index)




101 




118 




112 




139 




108 




102 






Abrasion resistance




98




120 




114 




94




105 




94






(index)






Wet skid resistance




96




104 




101 




108 




122 




124 






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.













In the comparative examples, the Mooney viscosities are high, and therefore the kneaded rubbers have very bad surfaces. Further, they are inferior in the dispersibility of carbon black and therefore reduced also in an abrasion resistance.
















TABLE 33














Comparative








Example




Example




Example


















125




126




107




108




127




128









Composition






(parts by weight)






NR






0120*


5






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




30




30




30




30




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




30




30






Type




N134




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




1.5




1.5




1.5






agent Si69






Fatty acid






ester-modified






silicone oil






A




3.0




 6




 8




0.6




—




—






B




—




—




—




—




3.0




—






C




—




—




—




—




—




3.0






D




—




—




—




—




—




—






Evaluation






E′ (index)




112 




108 




104 




102 




110 




108 






Abrasion resistance




105 




102 




95




96




106 




106 






(index)






Wet skid resistance




102 




102 




101 




100 




101 




102 






(index)

















Comparative








Example




Example

















109




110




129




130




131









Composition






(parts by weight)






NR




—




—




40




—




—






0120*5




94.5 




94.5 




81




94.5 




94.5 






BR01




30




30




—




30




30






Aromatic oil




5.5




5.5




 9




5.5




5.5






Silica




30




30




30




27




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




27






Type




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




—




—






agent Si69






Fatty acid






ester-modified






silicone oil






A




—




—




3.0






 


 3.0*


6








 


 3.0*


7








B




—




—




—




—






C




—




—




—




—






D




3.0




—




—




—






E




—




3.0




—




—






Evaluation






E′ (index)




104 




100 




115 




114 




112 






Abrasion resistance




96




94




102 




105 




104 






(index)






Wet skid resistance




100 




99




104 




103 




104 






(index)











*


5


Emulsion-polymerized styrene-butadiene rubber having a styrene content of 35% (oil-extended with aromatic oil of 37.5 parts by weight).










*


6


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.










*


7


Silica obtained by carrying Sample A on N134 in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of carbon black (N134) was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.













Comparative Examples 111 to 120 and Examples 132 to 144




Rubber compositions were prepared in the recipes shown in the following Tables 35 and 36 according to the basic recipe shown in Table 1 described previously. Shown respectively are various carbon blacks in Table 21 and various α,ω-dihydroxypolydimethylsiloxanes in the following Table 34 each of which is used for the above compositions.














TABLE 34


























g



























Sample A




10







Sample B




40







Sample C




70







Sample D




120 















The rubber compositions obtained in the examples and the comparative examples were evaluated for a dynamic storage elastic modulus (E′), an abrasion resistance and a wet skid resistance by the evaluation methods described previously.

















TABLE 35













Comparative





Comparative




Ex-







Example




Example




Example




ample



















111




112




132




133




113




114




134









Composition






(parts by weight)






NR




—




—




—




—




—




—




—






0120*1




94.5 




94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




60




30




30




30




30




25






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




—




30




30




30




30




30






Type




N134




—




N134




N134




N134




N134




N134






Silane coupling




1.5




3




1.5




1.5




1.5




1.5




1.25






agent Si69*


4








α,ω-Dihydroxy-






polydimethyl-






siloxane






A




—




—




1.5




1.5




1.5




1.5




2.5






B




—




—




—




—




—




—




—






C




—




—




—




—




—




—




—






D




—




—




—




—




—




—




—






Evaluation






E′ (index)




100 




87




114 




106 




96




99




112 






Abrasion resistance




100 




84




108 




104 




94




106 




106 






(index)






Wet skid resistance




100 




118 




104 




104 




95




98




102 






(index)




















Com-





Com-





Com-







parative





parative





parative







Ex-





Ex-




Ex-




Ex-







ample




Example




ample




ample




ample


















115




135




136




116




137




117









Composition






(parts by weight)






NR




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




15




20




20




30




60




70






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




80




80




100 




20




10






Type




N134




N134




N134




N134




N134




N134






Silane coupling




 0.75




1.0




1.0




1.5




3.0




3.5






agent Si69*


4








α,ω-Dihydroxy-






polydimethyl-






siloxane






A




1.5




2.0




2.0




3.0




6.0




8.0






B




—




—




—




—




—




—






C




—




—




—




—




—




—






D




—




—




—




—




—




—






Evaluation






E′ (index)




102 




123 




118 




130 




116 




104 






Abrasion resistance




92




122 




114 




88




106 




92






(index)






Wet skid resistance




98




106 




101 




106 




116 




122 






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.













In the comparative examples, the Mooney viscosities are high, and therefore the kneaded rubbers have very bad surfaces. Further, they are inferior in the dispersibility of carbon black and therefore reduced also in an abrasion resistance.
















TABLE 36














Comparative








Example




Example




Example


















138




139




118




119




140




141









Composition






(parts by weight)






NR




—




—




—




—




—




—






0120*


5






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




30




30




30




30




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




30




30






Type




N134




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




1.5




1.5




1.5






agent Si69






α,ω-Dihydroxy-






polydimethyl-






siloxane






A




3.0




 6




 8




0.6




—




—






B




—




—




—




—




3.0




—






C




—




—




—




—




—




3.0






D




—




—




—




—




—




—






Evaluation






E′ (index)




118 




112 




106 




100 




112 




106 






Abrasion resistance




108 




104 




97




98




104 




101 






(index)






Wet skid resistance




104 




102 




100 




100 




102 




102 






(index)

















Comparative








Example




Example
















120




142




143




144









Composition






(parts by weight)






NR




—




40




—




—






0120*


5






94.5 




81




94.5 




94.5 






BR01




30




—




30




30






Aromatic oil




5.5




 9




5.5




5.5






Silica




30




30




27




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




27






Type




N134




N134




N134




N134






Silane coupling




1.5




1.5




—




—






agent Si69






α,ω-Dihydroxy-






polydimethyl-






siloxane






A




—




3.0




 


 


3.0*


6






 


 


3.0*


7








B




—




—




—






C




—




—




—






D




3.0




—




—






Evaluation






E′ (index)




102 




117 




116 




114 






Abrasion resistance




95




104 




109 




108 






(index)






Wet skid resistance




100 




104 




102 




102 






(index)











*


5


Emulsion-polymerized styrene-butadiene rubber having a styrene content of 35% (oil-extended with aromatic oil of 37.5 parts by weight).










*


6


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.










*


7


Silica obtained by carrying Sample A on N134 in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of carbon black (N134) was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.













Comparative Examples 121 to 131 and Examples 145 to 157




Rubber compositions were prepared in the recipes shown in the following Tables 38 and 39 according to the basic recipe shown in Table 1 described previously. Shown respectively are various carbon blacks in Table 21 and various hydrogen silicone oils in the following Table 37 each of which is used for the above compositions.














TABLE 37





































v




w




v + w




w/(v + w)



















Sample A




38




 8




46




0.18






Sample B




32




26




58




0.45






Sample C




32




61




93




0.66






Sample D




124 




82




206 




0.40






Sample E




43




 6




49




0.12














The rubber compositions obtained in the examples and the comparative examples were evaluated for a dynamic storage elastic modulus (E′), an abrasion resistance and a wet skid resistance by the evaluation methods described previously.

















TABLE 38













Comparative





Comparative




Ex-







Example




Example




Example




ample



















121




122




145




146




123




124




147









Composition






(parts by weight)






NR






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5




5.5






Silica




30




60




30




30




30




30




25






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




—




30




30




30




30




30






Type




N134




—




N134




N134




N134




N134




N134






Silane coupling




1.5




3




1.5




1.5




1.5




1.5




 1.25






agent Si69*


4








Hydrogen






silicone oil






A




—




—




1.5




1.5




1.5




1.5




2.5






B




—




—




—




—




—




—




—






C




—




—




—




—




—




—




—






D




—




—




—




—




—




—




—






E




—




—




—




—




—




—




—






Evaluation






E′ (index)




100 




87




108 




103 




92




96




102 






Abrasion resistance






(index)




100 




84




107 




104 




94




102 




102 






Wet skid resistance




100 




118 




102 




100 




96




98




100 






(index)




















Com-





Com-





Com-







parative





parative





parative







Ex-





Ex-




Ex-




Ex-







ample




Example




ample




ample




ample


















125




148




149




126




150




127









Composition






(parts by weight)






NR




—




—




—




—




—




—






0120*


1






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01*


1






30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica




15




20




20




30




60




70






(Nipsil AQ)*


2








Carbon black*


3








Blend amount




30




80




80




100 




20




10






Type




N134




N134




N134




N134




N134




N134






Silane coupling




 0.75




1.0




1.0




1.5




3.0




3.5






agent Si69*


4








Hydrogen






silicone oil






A




1.5




2.0




2.0




3.0




6.0




8.0






B




—




—




—




—




—




—






C




—




—




—




—




—




—






D




—




—




—




—




—




—






E




—




—




—




—




—




—






Evaluation






E′ (index)




97




117 




112 




134 




104 




98






Abrasion resistance




97




122 




118 




88




102 




95






(index)






Wet skid resistance




96




104 




102 




108 




122 




125 






(index)











*


1


manufactured by Japan Synthetic Rubber Co., Ltd.










*


2


manufactured by Nippon Silica Ind. Co., Ltd.










*


3


manufactured by Tokai Carbon Co., Ltd.










*


4


Bis(3-triethoxysilylpropyl)tetrasulfide manufactured by Degussa AG.













In the comparative examples, the Mooney viscosities are high, and therefore the kneaded rubbers have very bad surfaces. Further, they are inferior in the dispersibility of carbon black and therefore reduced also in an abrasion resistance.
















TABLE 39














Comparative








Example




Example




Example


















151




152




128




129




153




154









Composition






(parts by weight)






NR






0120*


5






94.5 




94.5 




94.5 




94.5 




94.5 




94.5 






BR01




30




30




30




30




30




30






Aromatic oil




5.5




5.5




5.5




5.5




5.5




5.5






Silica






(Nipsil AQ)




30




30




30




30




30




30






Carbon black






Blend amount




30




30




30




30




30




30






Type




N134




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




1.5




1.5




1.5






agent Si69






Hydrogen






silicone oil






A




3.0




 6




 8




0.6




—




—






B




—




—




—




—




3.0




—






C




—




—




—




—




—




3.0






D




—




—




—




—




—




—






E




—




—




—




—




—




—






Evaluation






E′ (index)




110 




108 




106 




101 




110 




107 






Abrasion resistance




104 




102 




98




98




106 




108 






(index)






Wet skid resistance




103 




102 




102 




100 




102 




103 






(index)

















Comparative








Example




Example

















130




131




155




156




157









Composition






(parts by weight)






NR




—




—




40




—




—






0120*


5






94.5 




94.5 




81




94.5 




94.5 






BR01




30




30




—




30




30






Aromatic oil




5.5




5.5




 9




5.5




5.5






Silica




30




30




30




27




30






(Nipsil AQ)






Carbon black






Blend amount




30




30




30




30




27






Type




N134




N134




N134




N134




N134






Silane coupling




1.5




1.5




1.5




—




—






agent Si69






Hydrogen






silicone oil






A




—




—




3.0






 


 3.0*


6








 


 3.0*


7








B




—




—




—




—






C




—




—




—




—






D




3.0




—




—




—






E




—




3.0




—




—






Evaluation






E′ (index)




106 




101 




112 




109 




108 






Abrasion resistance




98




94




101 




105 




104 






(index)






Wet skid resistance




104 




101 




106 




102 




103 






(index)











*


5


Emulsion-polymerized styrene-butadiene rubber having a styrene content of 35% (oil-extended with aromatic oil of 37.5 parts by weight).










*


6


Silica obtained by carrying Sample A on Nipsil AQ in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of Nipsil AQ was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.










*


7


Silica obtained by carrying Sample A on N134 in a ratio 1:1 was used in an amount of 6 parts by weight. To be specific, 100 g of carbon black (N134) was put in a Henschel mixer, and 100 g of silicone oil was added thereto. The mixture was stirred at room temperature for 10 minutes to obtain a silica sample carrying the silicone oil.













As explained above, in the rubber compositions of the present invention, effective vulcanization is carried out, the wet performance is improved and the abrasion resistance is improved as well by blending a prescribed amount of specific carbon black and a prescribed amount of silica and mixing a specific amount of the specific silicone oil as a dispersion-improving agent into the blended silica. In addition thereto, the dry performance is improved as well since the dynamic storage elastic modulus (E′) goes up.




INDUSTRIAL APPLICABILITY




The rubber composition of the present invention can suitably be used for uses in which the processability (Mooney viscosity), the low heat generating property and the high abrasion resistance are required. In particular, it can suitably be applied to rubber products such as tires, conveyor belts and hoses.



Claims
  • 1. A rubber composition prepared by blending 15 to 85 parts by weight of silica per 100 parts by weight of a rubber component comprising a natural rubber and/or diene base synthetic rubber and 1 to 15% by weight of a dispersion-improving agent based on the amount of said silica, wherein the dispersion-improving agent is a compound selected from the group consisting of silicone oils represented by formulae (IV) to (VII): wherein R5 represents an alkyl group or a phenyl group; 1≦m+n≦200 and n/(m+n)≧0.15; X1 represents an amino group or an N-substituted amino group represented by —R1NR2R3 or —R1NHR4NR2R3; R1 and R4 represent —(CH2)n— (provided that n is 1, 2 or 3); R2 and R3 may be the same or different and represent a hydrogen atom, an alkyl group having 1 to 36 carbon atoms or a phenyl group; m and n represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure), wherein R6 represents an alkyl group or a phenyl group; 1≦p+q≦200 and q/(p+q)≧0.15; X2 represents a fatty acid ester group represented by —OCOR7; R7 represents an alkyl group or an alkenyl group each of which has 1 to 36 carbon atoms; p and q represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure), wherein R8 represents an alkyl group or a phenyl group; 1≦r+s≦200 and r/(r+s)≧0.15; X3 represents an epoxy-containing group represented by r and s represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure), wherein R9 represents an alkyl group or a phenyl group; 1≦t+u≦200 and u/(t+u)≧0.15; X4 represents an alkoxyl group; t and u represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 2. A rubber composition prepared by blending 15 to 85 parts by weight of silica per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber and 1 to 15% by weight of a dispersion-improving agent based on the amount of said silica, wherein said dispersion-improving agent is a nitrogen-containing carbonyl compound represented by any of the following Formulas (I) to (III): wherein R represents hydrogen, a linear or branched and saturated or unsaturated aliphatic hydrocarbon having 1 to 20 carbon atoms, an aromatic hydrocarbon or an alicyclic hydrocarbon and may be the same or different.
  • 3. The rubber composition as described in claim 1, wherein said dispersion-improving agent is an amine-modified silicone oil represented by the following Formula (IV): wherein R5 represents an alkyl group or a phenyl group; 1≦m+n≦200 and n/(m+n)≧0.15; X1 represents an amino group or an N-substituted amino group represented by —R1NR2R3 or —R1NHR4NR2R3; R1 and R4 represent —(CH2)n— (provided that n is 1, 2 or 3); R2 and R3 may be the same or different and represent a hydrogen atom, an alkyl group having 1 to 36 carbon atoms or a phenyl group; m and n represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 4. The rubber composition as described in claim 3, wherein the alkyl group represented by R5 in said formula has 1 to 3 carbon atoms.
  • 5. The rubber composition as described in claim 1, wherein said dispersion-improving agent is a fatty acid ester-modified silicone oil represented by the following Formula (V): wherein R6 represents an alkyl group or a phenyl group; 1≦p+q≦200 and q/(p+q)≧0.15; X2 represents a fatty acid ester group represented by —OCOR7; R7 represents an alkyl group or an alkenyl group each of which has 1 to 36 carbon atoms; p and q represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 6. The rubber composition as described in claim 5, wherein the alkyl group represented by R6 in said formula has 1 to 3 carbon atoms.
  • 7. The rubber composition as described in claim 1, wherein said dispersion-improving agent is an epoxy-modified silicone oil represented by the following Formula (VI): wherein R8 represents an alkyl group or a phenyl group; 1≦r+s≦200 and s/(r+s)≧0.15; X3 represents an epoxy-containing group represented by r and s represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 8. The rubber composition as described in claim 7, wherein the alkyl group represented by R8 in said formula has 1 to 3 carbon atoms.
  • 9. The rubber composition as described in claim 1, wherein said dispersion-improving agent is an alkoxyl-modified silicone oil represented by the following Formula (VII): wherein R9 represents an alkyl group or a phenyl group; 1≦t+u≦200 and u/(t+u)≧0.15; X4 represents an alkoxyl group; t and u represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 10. The rubber composition as described in claim 9, wherein the alkyl group represented by R9 in said formula has 1 to 3 carbon atoms, and the alkoxyl group represented by X4 has 1 to 3 carbon atoms.
  • 11. The rubber composition as described in claim 1, wherein said dispersion-improving agent is α,ω-dihydroxypolydimethylsiloxane represented by the following Formula (VIII):
  • 12. The rubber composition as described in claim 3, 5, 7, 9 or 11, wherein an inorganic filler on which 30% by weight or more of said dispersion-improving agent is carried in advance is used such that the proportion of the dispersion-improving agent is controlled to 3 to 15% by weight based on the amount of silica.
  • 13. The rubber composition as described in any of claims 2 to 11, further comprising a silane coupling agent which is blended in a proportion of 1 to 15% by weight based on the blending amount of silica.
  • 14. The rubber composition as described in claim 13, wherein said silane coupling agent is represented by the following Formula (X) or (XI):Y31—Si—CbH2bSaCbH2bSi—Y31 orY31—SiCbH2b—X5  (X) wherein X5 represents a nitroso group, a mercapto group, a thiocyanate group, an amino group, an epoxy group, a vinyl group, a chlorine atom or an imide group; Y1 represents an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a chlorine atom and may be the same or different; a represents an integer of 1 or more; and b represents an integer of 1 to 6:Y32—SiCbH2bSa—X6 or   (XI) wherein X6 is represented by any of the following formulas: Y2 represents an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a chlorine atom and may be the same or different; a represents an integer of 1 or more; and b represents an integer of 1 to 6.
  • 15. The rubber composition as described in claim 13, wherein said silane coupling agent is at least one compound selected from the group consisting of bis(3-triethoxysilylpropyl)polysulfide, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-thiocyanatepropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, trimethoxysilylpropylmercaptobenzothiazole tetrasulfide, triethoxysilylpropylmethacrylate monosulfide and dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide.
  • 16. The rubber composition as described in claim 13, wherein said silane coupling agent is bis(3-triethoxysilylpropyl)polysulfide.
  • 17. The rubber composition as described in any of claims 2 to 11, further comprising carbon black as a reinforcing filler which is blended in an amount of 20 to 80 parts by weight per 100 parts by weight of the rubber component.
  • 18. A rubber composition prepared by blending 20 to 60 parts by weight of silica and 30 to 80 parts by weight of carbon black having a cetyl trimethylammonium bromide-adsorbing amount (CTAB) of 120 m2/g or more and a dibutyl phthalate-absorbing amount (DBP) of 120 ml/100 g or more per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber, and 3 to 15% by weight of a dispersion-improving agent based on the amount of silica, wherein the total amount of silica and carbon black is 50 to 120 parts by weight and the dispersion-improving agent is a compound selected from the group consisting of silicone oils represented by formulae (IV) to (VII) and (IX): wherein R5 represents an alkyl group or a phenyl group; 1≦m+n≦200 and n/(m+n)≧0.15; X1 represents an amino group or an N-substituted amino group represented by —R1NR2R3 or —R1NHR4NR2R3; R1 and R4 represent —(CH2)n— (provided that n is 1, 2 or 3); R2 and R3 may be the same or different and represent a hydrogen atom, an alkyl group having 1 to 36 carbon atoms or a phenyl group; m and n represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure), wherein R6 represents an alkyl group or a phenyl group; 1≦p+q≦200 and q/(p+g)≧0.15; X2 represents a fatty acid ester group represented by —OCOR7; R7 represents an alkyl group or an alkenyl group each of which has 1 to 36 carbon atoms; p and q represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure), wherein R8 represents an alkyl group or a phenyl group, 1≦r+s≦200 and r/(r+s)≧0.15; X3 represents an epoxy-containing group represented by r and s represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure), wherein R9 represents an alkyl group or a phenyl group; 1≦t+u≦200 and u/(t+u)≧0.15; X4 represents an alkoxyl group; t and u represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure), wherein R10 represents an alkyl group or a phenyl group; 1≦v+w≦200 and w/(v+w)≧0.15; v and w represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 19. The rubber composition as described in claim 18, wherein said dispersion-improving agent is an amine-modified silicone oil represented by the following Formula (IV): wherein R5 represents an alkyl group or a phenyl group; 1≦m+n≦200 and n/(m+n)≧0.15; X1 represents an amino group or an N-substituted amino group represented by —R1NR2R3 or —R1NHR4NR2R3; R1 and R4 represent —(CH2)n— (provided that n is 1, 2 or 3); R2 and R3 may be the same or different and represent a hydrogen atom, an alkyl group having 1 to 36 carbon atoms or a phenyl group; m and n represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 20. The rubber composition as described in claim 19, wherein the alkyl group represented by R5 in said formula has 1 to 3 carbon atoms.
  • 21. The rubber composition as described in claim 18, wherein said dispersion-improving agent is a fatty acid ester-modified silicone oil represented by the following Formula (V): wherein R6 represents an alkyl group or a phenyl group; 1≦p+q≦200 and q/(p+q)≧0.15; X2 represents a fatty acid ester group represented by —OCOR7; R7 represents an alkyl group or an alkenyl group each of which has 1 to 36 carbon atoms; p and q represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 22. The rubber composition as described in claim 21, wherein the alkyl group represented by R6 in said formula has 1 to 3 carbon atoms.
  • 23. The rubber composition as described in claim 18, wherein said dispersion-improving agent is an epoxy-modified silicone oil represented by the following Formula (VI): wherein R8 represents an alkyl group or a phenyl group; 1≦r+s≦200 and s/(r+s)≧0.15; X3 represents an epoxy-containing group represented by r and s represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 24. The rubber composition as described in claim 23, wherein the alkyl group represented by R8 in said formula has 1 to 3 carbon atoms.
  • 25. The rubber composition as described in claim 18, wherein said dispersion-improving agent is an alkoxy-modified silicone oil represented by the following Formula (VII): wherein R9 represents an alkyl group or a phenyl group; 1≦t+u≦200 and u/(t+u)≧0.15; X4 represents an alkoxyl group; t and u represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 26. The rubber composition as described in claim 25, wherein the alkyl group represented by R9 in said formula has 1 to 3 carbon atoms, and the alkoxyl group represented by X4 has 1 to 3 carbon atoms.
  • 27. The rubber composition as described in claim 18, wherein said dispersion-improving agent is α,ω-dihydroxypolydimethylsiloxane represented by the following Formula (VIII):
  • 28. The rubber composition as described in claim 18, wherein said dispersion-improving agent is a hydrogen silicone oil represented by the following Formula (IX): wherein R10 represents an alkyl group or a phenyl group; 1≦v+w≦200 and w/(v+w)≧0.15; v and w represent the total number of the respective structural units and include a continuous one (block structure) and one disposed at random (random structure).
  • 29. The rubber composition as described in claim 28, wherein the alkyl group represented by R10 in said formula has 1 to 3 carbon atoms.
  • 30. The rubber composition as described in claim 19, 21, 23, 25, 27 or 28, wherein an inorganic filler on which 30% by weight or more of said dispersion-improving agent is carried in advance is used such that the proportion of the dispersion-improving agent is controlled to 3 to 15% by weight based on the amount of silica.
  • 31. The rubber composition as described in claim 18, further comprising a silane coupling agent in a proportion of 1 to 15% by weight based on the blending amount of silica.
  • 32. The rubber composition as described in claim 31, wherein said silane coupling agent is represented by the following Formula (X) or (XI):Y31—Si—CbH2bSaCbH2bSi—Y31 Y31—SiCbH2b—X5  (X) wherein X5 represents a nitroso group, a mercapto group, a thiocyanate group, an amino group, an epoxy group, a vinyl group, a chlorine atom or an imide group; Y1 represents an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a chlorine atom and may be the same or different; a represents an integer of 1 or more; and b represents an integer of 1 to 6:Y32—SiCbH2bSa—X6  (XI) wherein X6 is represented by any of the following formulas: Y2 represents an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a chlorine atom and may be the same or different; a represents an integer of 1 or more; and b represents an integer of 1 to 6.
  • 33. The rubber composition as described in claim 31 or 32, wherein said silane coupling agent is at least one compound selected from the group consisting of bis(3-triethoxysilylpropyl)polysulfide, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-thiocyanatepropyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, trimethoxysilylpropylmercaptobenzothiazole tetrasulfide, triethoxysilylpropylmethacrylate monosulfide and dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide.
  • 34. The rubber composition as described in claim 31, wherein said silane coupling agent is bis(3-triethoxysilylpropyl)polysulfide.
  • 35. A rubber composition prepared by blending 20 to 60 parts by weight of silica and 30 to 80 parts by weight of carbon black having a cetyl trimethylammonium bromide-adsorbing (CTAB) of 120 m2/g or more and a dibutyl phthalate-absorbing amount (DBP) of 120 ml/100 g or more per 100 parts by weight of a rubber component comprising natural rubber and/or diene base synthetic rubber, and 3 to 15% by weight of a dispersion-improving agent based on the amount of silica, wherein the total amount of silica and carbon black is 50 to 120 parts by weight and the dispersion-improving agent is a nitrogen-containing carbonyl compound represented by any of the following Formulas (I) to (III): wherein R represents hydrogen, a linear or branched and saturated or unsaturated aliphatic hydrocarbon having 1 to 20 carbon atoms, an aromatic hydrocarbon or an alicyclic hydrocarbon and may be the same or different.
Priority Claims (6)
Number Date Country Kind
8-166448 Jun 1996 JP
8-215040 Jul 1996 JP
8-215041 Jul 1996 JP
8-215042 Jul 1996 JP
8-215043 Jul 1996 JP
8-219557 Aug 1996 JP
PCT Information
Filing Document Filing Date Country Kind 102e Date 371c Date
PCT/JP97/02223 WO 00 2/19/1998 2/19/1998
Publishing Document Publishing Date Country Kind
WO97/35918 10/2/1997 WO A
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Number Name Date Kind
3873489 Thurn et al. Mar 1975
3957718 Pochert et al. May 1976
5026762 Kida et al. Jun 1991
5198171 Kasahara et al. Mar 1993
5719207 Cohen et al. Feb 1998
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