Multi-component copolymer rubber, a process for producing the same and a rubber composition containing the multi-component copolymer rubber

This invention relates to a novel multi-component copolymer rubber consisting essentially of a cyano-substituted alkyl (meth)acrylate, an alkyl acrylate and a diene monomer, excellent in heat resistance, ozone resistance, sour gasoline resistance and sour gasohol resistance, as well as to a rubber composition containing said multi-component copolymer rubber and other components.
In recent years, in automobiles, gasoline-resistant rubbers are in use in atmospheres whose temperatures are becoming increasingly higher in connection with countermeasures for exhaust gas regulations and engine modifications for higher performance. Hence, there is now required a gasoline-resistant rubber excellent in heat resistance and ozone resistance. With respect to these gasoline-resistant rubbers, there is a further problem that gasolines are oxidized in fuel systems of automobiles, etc. to produce a sour gasoline [the sour gasoline refers to a gasoline containing peroxides produced by gasoline oxidation at high temperatures and it is described in detail in A. Nersasian, Rubber and Plastics News, June 26 (1978)] and this sour gasoline deteriorates gasoline-resistant rubbers.
In connection with tight supply of crudes on worldwide basis, addition of an alcohol to a gasoline has been tried. This gasoline-alcohol mixture, namely, gasohol is also oxidized to produce a sour gasohol and this sour gasohol deteriorates gasoline-resistant rubbers as well.
As gasoline-resistant rubbers, butadiene-acrylonitrile rubber has widely been used in such applications as hoses, gaskets, O-rings, packings and oil seals. However, butadiene-acrylonitrile rubber is poor in ozone resistance and insufficient in heat resistance and sour gasoline resistance, and therefore, it is difficult to provide a rubber part having a sufficient reliability even when used in contact with a gasoline at high temperatures as mentioned above.
In order to overcome the drawbacks of butadiene-acrylonitrile rubber, it is known to use a blend of butadiene-acrylonitrile rubber with poly(vinyl chloride), thereby improving sour gasoline resistance and ozone resistance [Japanese Patent Application Kokai (Laid-Open) No. 89,388/80]. However, this blend has no improved heat resistance, is poor in other properties such as low-temperature resistance and permanent compression set, which are required as gasoline-resistant rubber materials and cannot be said to have sufficient gasohol resistance. Hence, it has been desired to overcome these drawbacks. Fluororubber has been spotlighted as a gasoline-resistant rubber material because of its excellency in sour gasoline resistance, ozone resistance and heat resistance. However, the fluororubber has an insufficient flexibility at low temperatures, and poor physical properties, and is difficult to handle and very expensive. Accordingly it cannot be used as a general purpose gasoline resistant rubber.
Under such circumstances, the present inventors have studied on various materials which are excellent in heat resistance, ozone resistance, sour gasoline resistance and sour gasohol resistance and which can easily be used as a gasoline-resistant and gasohol-resistant material using conventional molding equipments and techniques. As a result, it has been found that the above requirements can be met by a novel multi-component copolymer consisting essentially of a cyano-substituted alkyl (meth)acrylate, an alkyl acrylate and a crosslinkable monomer and also by a composition of said multi-component copolymer and other components.
According to this invention, there is provided a multi-component copolymer rubber consisting essentially of
(A) 20 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate,
(B) 30 to 79.5% by weight of an alkyl acrylate,
(C) 0.5 to 10% by weight of a crosslinkable monomer, and
(D) 0 to 10% by weight of other ethylenically unsaturated monomer copolymerizable with the components (A), (B) and (C).
This invention further provides a process for producing said copolymer rubber, a composition of said copolymer rubber and other components, and uses of said copolymer rubber and said composition.
The cyano-substituted alkyl (meth)acrylate which is the component (A) of the multi-component copolymer rubber of this invention is represented by the formula (I): ##STR1## wherein R.sup.1 is a hydrogen atom or a methyl group and R.sup.2 is an alkylene group. In the formula (I), --R.sup.2 --CN is a cyanoalkyl group of 2 to 12 carbon atoms. Specific examples of the cyano-substituted alkyl (meth)acrylate are cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 2-cyanopropyl (meth)acrylate, 3-cyanopropyl (meth)acrylate, 4-cyanobutyl (meth)acrylate, 6-cyanohexyl (meth)acrylate, 2-ethyl-6-cyanohexyl (meth)acrylate, 8-cyanooctyl (meth)acrylate, etc. Of these, preferred are 2-cyanoethyl acrylate, 3-cyanopropyl acrylate and 4-cyanobutyl acrylate. Particularly, 2-cyanoethyl acrylate is preferred.
The alkyl acrylate which is the component (B) is represented by the formula (II): ##STR2## wherein R.sup.3 is an alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl acrylate are methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate, etc. Of these, preferred are ethyl acrylate, propyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate and n-octyl acrylate. Particularly, ethyl acrylate and n-butyl acrylate are preferred.
As the crosslinkable monomer which is the component (C), there can be used (C-I) a diene compound, (C-II) a (meth)acrylic acid ester containing a dihydrodicyclopentadienyl group, (C-III) an epoxy group-containing, ethylenically unsaturated compound, (C-IV) an active halogen-containing, ethylenically unsaturated compound, (C-V) an active hydrogen-containing monomer and (C-VI) a carboxyl group-containing monomer.
The diene compound (C-I) includes non-conjugated dienes such as alkylidenenorbornenes, alkenylnorbornenes, dicyclopentadiene, methylcyclopentadiene and dimers thereof as well as conjugated dienes such as butadiene and isoprene. Of these, non-conjugated dienes are preferred, and alkylidenenorbornenes are particularly preferred. Of the alkylidenenorbornenes, ethylidenenorbornene is most preferable.
(meth)acrylic acid ester containing a dihydrodicyclopentadienyl group (C-II) includes dihydrodicyclopentadienyl (meth)acrylate, dihydrodicyclopentadienyl oxyethyl (meth)acrylate and the like.
The epoxy group-containing, ethylenically unsaturated monomer (C-III) includes allyl glycidyl ether, vinyl glycidyl ether, 2-methyl-1-propenyl glycidyl ether, glycidyl methacrylate and glycidyl acrylate. Of these, allyl glycidyl ether, glycidyl methacrylate and glycidyl acrylate are preferred. Allyl glycidyl ether is most preferable.
The active halogen-containing, ethylenically unsaturated compound (C-IV) includes vinylbenzyl chloride, vinylbenzyl bromide, 2-chloroethyl vinyl ether, vinyl chloroacetate, ethylene chloroacetate methacrylate, vinyl chloropropionate, allyl chloroacetate, allyl chloropropionate, 2-chloroethyl acrylate, 2-chloroethyl methacrylate, 2-hydroxypropylene chloroacetate methacrylate, chloromethyl vinyl ketone, 2-chloroacetoxymethyl-5-norbornene, norbornylmethyl chloroacetate, 4-chloromethylstyrene, vinyl chloride, vinylidene chloride, etc. Of these, preferred are vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, vinylbenzyl chloride, 2-chloroethyl methacrylate and 2-chloroethyl acrylate.
The active hydrogen-containing monomer (C-V) includes allyl cyanoacetate, etc.
The carboxyl group-containing monomer includes acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, etc.
The other ethylenically unsaturated monomer which is the component (D) is an optional component. It includes methacrylates such as methyl methacrylate, octyl methacrylate and the like; alkoxyalkyl acrylates such as methoxyethyl acrylate, butoxyethyl acrylate and the like; alkyl vinyl ketones such as methyl vinyl ketone and the like; vinyl ethers and allyl ethers such as vinyl ethyl ether, allyl methyl ether and the like; vinyl aromatic compounds such as styrene, .alpha.-methylstyrene, chlorostyrene, vinyltoluene and the like; alkenylnitriles such as acrylonitrile, methacrylonitrile and the like; alkenylamides such as acrylamide, methacrylamide, N-methylolacrylamide and the lke; and alkyl fumarates.
The proportions of the components (A), (B), (C) and (D) in the copolymer rubber of this invention are 20 to 69.5%, preferably 25 to 60%, by weight of the component (A), 30 to 79.5%, preferably 35 to 75%, by weight of the component (B), 0.5 to 10%, preferably 0.5 to 5%, by weight of the component (C) and 0 to 10%, preferably 0 to 7%, by weight of the component (D).
When the component (A) is less than 20% by weight, the copolymer rubber is poor in gasoline resistance and sour gasoline resistance. When the component (A) exceeds 69.5% by weight, the copolymer rubber is poor in physical properties such as tensile strength and elongation.
When the component (B) is less than 30% by weight, the multi-component copolymer rubber is poor in physical properties. When the component (B) exceeds 79.5% by weight, the multi-component copolymer rubber is deteriorated in gasoline resistance and sour gasoline resistance.
When the component (C) is less than 0.5% by weight, the multi-component copolymer rubber requires a long time for crosslinking and has no sufficient tensile strength as possessed by crosslinked rubbers. When the component (C) exceeds 10% by weight, the multi-component copolymer rubber becomes hard and has a reduced elongation.
The glass transition temperature of the multi-component copolymer rubber of this invention is preferably a glass transition temperature of -10.degree. C. or less.
The multi-component copolymer rubber of this invention can easily be produced by subjecting to radical polymerization a mixture consisting of (A) 15 to 70% by weight of a cyano-substituted alkyl (meth)acrylate, (B) 30 to 84.5% by weight of an alkyl acrylate, (C) 0.5 to 15% by weight of a crosslinkable monomer and (D) 0 to 15% by weight of an ethylenically unsaturated monomer copolymerizable with (A), (B) and (C). This radical polymerization can be conducted by a conventional polymerization method such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization, wherein the monomers and other components are added at one time, continuously or intermittently.
The radical polymerization initiator used in the above polymerization may be conventional free radical catalysts such as peroxides, redox catalysts, persulfates and azo compounds. The polymerization can be conducted at a temperature ranging from 0.degree. C. to 80.degree. C., preferably 5.degree. C. to 60.degree. C.
The multi-component rubber obtained by the above polymerization can be recovered by a conventional coagulation method using a metal salt such as calcium chloride or the like or using a non-solvent such as ethanol, methanol or the like.
The form of the multi-component copolymer rubber of this invention is not critical, and the multi-component copolymer rubber can be produced in a solid form or in a liquid form depending upon the uses. The molecular weight of the multi-component copolymer rubber is not critical; however, when used in a solid form, the multi-component copolymer rubber has preferably a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 20 to 150, more preferably 25 to 100.
Into the multi-component copolymer rubber of this invention can optionally be incorporated conventional compounding agents such as a crosslinking agent, a crosslinking accelerator, a reinforcing agent, a filler, a plasticizer, a softener, an aging inhibitor, a stabilizer, a foaming agent and the like. The resulting compound can be subjected to crosslinking by a conventional method to easily obtain a crosslinked product.
As the above crosslinking agent, an appropriate compound may be selected depending upon the type of the functional group to be used in the formation of crosslinkage of the copolymer. For example, when a diene compound or a (meth)acrylic acid ester containing a dihydrodicyclopentadienyl group is introduced into the copolymer by copolymerization to form carbon-carbon double bonds in the copolymer, there can preferably be used conventional crosslinking agents which are employed for diene type rubbers (styrene-butadiene rubber, isoprene rubber, butadiene-acrylonitrile rubber, etc.), such as vulcanizing agents (e.g. sulfur, thiuram compound) and organic peroxides. When an epoxy group-containing monomer is introduced, the crosslinking agents may be ammonium compounds, polyamines, polyamine salts, a combination of a polyamine with sulfur or dibenzothiazyl disulfide, dithiocarbamic acid salts, a combination of sulfur with a metal salt of a fatty acid, a combination of sulfur with a metal salt of a fatty acid and a maleimide, thiourea derivatives, and a combination of a thiourea derivative with red lead or dibasic lead phosphite. When an active halogen-containing, ethylenically unsaturated compound is used, the crosslinking agents may be polyamines, polyamine salts, a combination of a polyamine with sulfur or dibenzothiazyl disulfide, ammonium compounds, a combination of a metal salt of a fatty acid with sulfur, a combination of a metal salt of a fatty acid with sulfur and a maleimide, thiourea derivatives, and a combination of a thiourea derivative and red lead or dibasic lead phosphite. When an active hydrogen-containing monomer is used, the crosslinking agents may be tetramethylthiuram disulfide or tetraethylthiuram disulfide. When a carboxyl group-containing monomer is used, the crosslinking agents may be zinc oxide or lead oxide. When the ammonium compounds are used as the crosslinking agent, they may be, for example, ammonium benzoate or ammonium adipate. When the polyamines are used, they may be, for example, triethylenetetramine, hexamethylenetetramine or triethyltrimethylenetriamine. An example of the polyamine salts is hexamethylenediamine carbamate. Examples of the dithiocarbamic acid salts are zinc dimethyldithiocarbamate and iron dimethyldithiocarbamate. Examples of the metal salts of fatty acids are sodium myristate, sodium palmitate, sodium stearate, sodium arachate, sodium behenate and their corresponding potassium salts. Examples of the thiourea derivatives are 2-mercaptoimidazoline and N,N'-diethylthiourea. An example of the maleimides is N,N'-m-phenylenebismaleimide.
The amount of the crosslinking agent used in this invention is not critical and may be varied appropriately depending upon the type and amount of crosslinkable monomer used and also depending upon the type of crosslinking agent used. For example, an ammonium compound is used in an amount of 0.1 to 5 parts by weight; a polyamine or a polyamine salt used in an amount of 0.1 to 5 parts by weight; sulfur used in an amount of 0.1 to 2 parts by weight; a dithiocarbamic acid salt used in an amount of 0.1 to 10 parts by weight; a metal salt of a fatty acid used in an amount of 0.1 to 10 parts by weight; and a thiourea derivative used in an amount of 0.1 to 5 parts by weight.
The crosslinked product of a vulcanizable rubber composition containing the multi-component copolymer rubber of this invention and a crosslinking agent excels in gasoline resistance, sour gasoline resistance, heat resistance and ozone resistance and has good low-temperature resistance, tensile strength and elongation, and has a small permanent compression set. Therefore, it can be used in fuel system hoses of automobiles; other hoses, diaphragms and sealing materials (e.g. gasket, O-ring, oil seal) which come in contact with fuels, hydraulic oils, lubricating oils, etc.; rolls, transfer belts and conveyor belts requiring oil resistance and solvent resistance which are used in iron manufacure, spinning, printing, paper making, dyeing, etc.; and so forth. Being excellent particularly in sour gasoline resistance, the vulcanizable rubber composition can preferably be used as a rubber for fuel system hoses of automobiles.
A rubber compound obtained by optionally incorporating into the multi-component copolymer rubber of this invention, conventional compounding chemicals such as a reinforcing agent, a filler, a plasticizer, a softener, a crosslinking agent, a stabilizer and the like and further optionally incorporating polymers such as PVC, acrylic rubber, NBR, fluororubber, epichlorohydrin rubber and the like, is excellent in gasoline resistance, sour gasoline resistance, ozone resistance and heat resistance and further good in tensile strength, elongation and low-temperature resistance. Therefore, the rubber compound provides a very excellent material for use in inner tubes of fuel system rubber hoses of automobiles, particularly for use in inner tubes of rubber hoses connecting metal pipes in automobile engines.
In this invention, a mixture consisting of (A) a cyano-substituted alkyl (meth)acrylate, (B) an alkyl acrylate, (C) a crosslinkable monomer and (D) other ethylenically unsaturated monomer is emulsion-polymerized at 0.degree. C. to 80.degree. C. in the presence of a radical polymerization catalyst, and to the resulting polymerization mixture is added a metal salt or a combination of an inorganic acid and a metal salt to coagulate a copolymer rubber, after which a releasing agent is added to the copolymer rubber coagulated, to obtain a multi-component copolymer rubber composition which has good kneadability, excellent heat resistance, ozone resistance and sour gasoline resistance and good tensile strength and elongation.
The metal salt may be calcium chloride, magnesium sulfate or the like. The inorganic acid may be sulfuric acid, or the like.
The releasing agent may be hydrocarbon compound such as paraffin wax or the like; a fatty acid compound such as stearic acid or the like; a fatty acid amide compound; a fatty acid ester compound; a phosphoric acid ester compound; or a metal salt of a fatty acid. Of these, preferred are metal salts of fatty acids, phosphoric acid ester compounds and fatty acid ester compounds. Metal salts of fatty acids are more preferable in view of the good kneadability of the rubber composition obtained, and the addition of the metal salt does not result in any deterioration of the physical properties of the vulcanizate.
The amount of the releasing agent used is preferably 0.5 to 10 parts by weight per 100 parts by weight of the rubber. When the amount is less than 0.5 part by weight, the kneadability of the rubber composition obtained is not improved. When the amount exceeds 10 parts by weight, the physical properties of a vulcanizate of the rubber composition obtained are greatly deteriorated.
The releasing agent can be added mechanically by a conventional molding equipment such as a roll, a Banbury mixer, a kneader or the like. Alternatively, it can be added in the form of an emulsion.
Addition of a plasticizer is preferred for improvement of the low-temperature resistance. The plasticizer may be a phthalic acid derivative compound such as diethyl phthalate, di-(2-ethylhexyl)phthalate, dibutyl phthalate, di-n-octyl phthalate, dimethylcyclohexyl phthalate or the like; an isophthalic acid derivative compound such as diisooctyl isophthalate or the like; a tetrahydrophthalic acid derivative compound such as di-(2-ethylhexyl) tetrahydrophthalate or the like; an adipic acid derivative compound such as di-(2-ethylhexyl)adipate, di-(butoxyethoxyethyl)adipate, butyldiglycol adipate or the like; an azelaic acid derivative compound such as di-(2-ethylhexyl)azelate or the like; a sebacic acid derivative compound such as di-(2-ethylhexyl)sebacate, di-n-butyl sebacate or the like; a fatty acid derivative compound such as diethylene glycol monolaurate or the like; a phosphoric acid derivative compound such as tri(2-ethylhexyl)phosphate, triphenyl phosphate or the like; a glycol derivative compound such as dibutyl methylenebisthioglycolate or the like; a glycerine derivative compound; an epoxy derivative compound; or a polymeric plasticizer such as a polyester compound, a polyether compound, a polyetherester compound or the like. Of these, preferred are polymeric plasticizers having a molecular weight of 300 to 3,000 such as polyester compounds, polyether compounds and polyetherester compounds.
The plasticizer is added in an amount of 2 to 15 parts by weight per 100 parts by weight of the rubber. When it is used in an amount of less than 2 parts by weight, no sufficient improvement in low-temperature resistance is obtained. When the plasticizer is added in an amount of more than 15 parts by weight, reduction in tensile strength becomes large.
By further incorporating into the multi-component copolymer rubber of this invention a vinylidene fluoride polymer, a vinyl chloride resin, a nitrile rubber or a partially hydrogenated product thereof, or an acrylic rubber, a rubber composition can be produced which is excellent not only in gasoline resistance, gasohol resistance, sour gasoline resistance and sour gasohol resistance but also in ozone resistance, heat resistance and low-temperature resistance.
In this case, the multi-component copolymer rubber may consist essentially of
(A) 10 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate,
(B) 30 to 89.5% by weight of an alkyl acrylate,
(C) 0.5 to 10% by weight of a crosslinkable monomer, and
(D) 0 to 10% by weight of other ethylenically unsaturated monomer copolymerizable with the components (A), (B) and (C).
The vinylidene fluoride polymer mentioned above includes a poly(vinylidene fluoride) as well as copolymers between vinylidene fluoride and ethylene trifluoride, propylene pentafluoride, propylene hexafluoride, vinyl acetate, ethylene, propylene, butadiene, styrene, an acrylic acid ester or the like wherein the content of vinylidene fluoride is usually at least 40 mole %, preferably at least 60 mole %. The degree of polymerization of the vinylidene fluoride polymer is not critical but is preferably 100 to 100,000.
The vinyl chloride resin mentioned above includes a poly(vinyl chloride) as well as copolymers between vinyl chloride and vinyl acetate, ethylene, propylene, butadiene, styrene or the like wherein the content of vinyl chloride is usually at least 60 mole % and preferably at least 80 mole %. The degree of polymerization of the vinyl chloride resin is not critical but is preferably 500 to 2,000.
As the amount of the vinylidene fluoride polymer or the vinyl chloride resin in the rubber composition increases, the resinous property of the rubber composition increases. Hence, the upper limit of the amount of said polymer or resin is governed by this property, and is preferably 60 parts by weight or less.
The proportions of the multi-component copolymer rubber and the vinylidene fluoride polymer or the vinyl chloride resin in the rubber composition of this invention can be determined appropriately within the above-mentioned ranges depending upon the application purpose and the performance requirements.
The mixing method in the preparation of the composition of this invention is not critical, but the following methods may be used:
(1) A method wherein a multi-component copolymer rubber and a vinylidene fluoride polymer or a vinyl chloride resin are blended by a mixer such as a roll, a Banbury mixer, an intermixer or the like.
(2) A method wherein a multi-component copolymer rubber and a vinylidene fluoride polymer or a vinyl chloride resin are blended in a latex or suspension state and then subjected to coagulation and subsequent coprecipitation.
(3) A method wherein the methods (1) and (2) are combined.
Into the multi-component copolymer rubber composition can optionally be incorporated conventional compounding chemicals such as a reinforcing agent, a filler, a plasticizer, a softener, a crosslinking agent, a stabilizer and the like. The resulting mixture can be subjected to crosslinking by a conventional method to easily obtain a crosslinked material.
The multi-component copolymer rubber composition of this invention is excellent not only in gasoline resistance, sour gasoline resistance, ozone resistance and heat resistance but also in new performance requirements namely, gasohol resistance and sour gasohol resistance. In addition, the composition is good in tensile strength, elongation and low-temperature resistance. Therefore, the composition can be used in fuel system hoses of automobiles; other hoses, diaphragms and seals (e.g. gaskets, O-rings, oil seals) which come in contact with fuels, hydraulic oils, lubricating oils, etc.; rolls, transfer belts and conveyor belts requiring oil resistance and solvent resistance for use in iron manufacturing, spinning, printing, paper making, dyeing, etc.; and so forth. Utilizing the characteristic feature of the multi-component copolymer rubber composition being excellent in sour gasoline resistance and sour gasohol resistance, the composition can preferably be used in fuel system hoses of automobiles.
The acrylic rubber mentioned above is a multi-component copolymer rubber consisting of (A') 99.5 to 39.5% by weight of an alkyl acrylate, (B') 0 to 60% by weight of an alkoxyalkyl acrylate, (C') 0.5 to 10% by weight of at least one compound selected from the group consisting of diene compounds, (meth)acrylic acid esters containing a dihydrodicyclopentadienyl group, epoxy group-containing, ethylenically unsaturated compounds and active halogen-containing, ethylenically unsaturated compounds and (D') 0 to 10% by weight of other ethylenically unsaturated compound copolymerizable with (A'), (B') and (C'). The nitrile rubber mentioned above is a multi-component copolymer rubber composed of (A") 20 to 90% by weight of a conjugated diolefin, (B") 10 to 55% by weight of an .alpha.,.beta.-unsaturated nitrile, (C") 0 to 70% by weight of an .alpha.,.beta.-unsaturated carboxylic acid ester and (D") 0 to 20% by weight of at least one monomer selected from the group consisting of carboxyl group-containing monomers, epoxy group-containing monomers, hydroxyl group-containing monomers and amino group-containing monomers.
The alkyl acrylate which is the component (A') of the acrylic rubber is represented by the formula (II): ##STR3## wherein R.sup.3 is an alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl acrylate are as mentioned hereinbefore as to the component (B).
Specific examples of the alkoxyalkyl acrylate which is the component (B') of the acrylic rubber include methoxyethyl acrylate, ethoxyethyl acrylate and butoxyethyl acrylate.
As the component (C') of the acrylic rubber, there can be used the diene compounds, the (meth)acrylic acid esters containing a dihydroxypentadienyl group, the epoxy group-containing, ethylenically unsaturated compounds and the active halogen-containing, ethylenically unsaturated compounds, all of which have been mentioned with respect to the component (C) of the multi-component copolymer rubber of this invention.
The component (D'), namely, other ethylenically unsaturated compound copolymerizable with the components (A'), (B') and (C') may be various compounds. Specific examples of the component (D') include carboxyl group-containing compounds such as acrylic acid, methacrylic acid, crotonic acid, 2-pentanoic acid, maleic acid, fumaric acid, itaconic acid and the like; methacrylates such as methyl methacrylate, octyl methacrylate and the like; alkyl vinyl ketones such as methyl vinyl ketone and the like; alkenyl alkyl ethers such as vinyl ethyl ether, allyl methyl ether and the like; alkenyl aromatic compounds such as styrene, .alpha.-methylstyrene, chlorostyrene, vinyltoluene and the like; vinylnitriles such as acrylonitrile, methacrylonitrile and the like; vinylamides such as acrylamide, methacrylamide, N-methylolacrylamide and the like; vinyl chloride; vinylidene chloride; and alkyl fumarates.
The acrylic rubber used in this invention consists of 99.5 to 39.5% by weight of the component (A'), 0 to 60% by weight of the component (B'), 0.5 to 10% by weight of the component (C') and 0 to 10% by weight of the component (D'). When the component (A') is less than 39.5% by weight, the acrylic rubber has low heat-resistance. When the component (B') exceeds 60% by weight, the rubber has low heat-resistance. When the component (C') is less than 0.5% by weight, the rubber is insufficient in crosslinkability and poor in physical properties, particularly in normal physical properties such as permanent compression set. When the component (C') exceeds 10% by weight, the rubber has low heat-resistance. When the component (D') optionally used exceeds 10% by weight, the rubber has a poor balance between oil resistance and low-temperature resistance.
The mixing ratio of the acrylic rubber and the multi-component copolymer rubber of this invention is not critical. However, in order to improve the kneadability, vulanization speed, permanent compression set and gasoline resistance of the acrylic rubber, it is desirable to use 5% by weight or more of the latter rubber. When the multi-component copolymer rubber is used in an amount of less than 5% by weight, the effect is small. In order to improve the heat resistance of the multi-component copolymer rubber, it is preferable to use 10% by weight or more of the acrylic rubber. When the acrylic rubber is used in an amount of less than 10% by weight, the effect is small.
According to this invention, the processability, vulcanization speed and permanent compression set which are the drawbacks of the conventional acrylic rubber can be improved. At the same time, it is made possible to freely control the balance of gasoline resistance, heat resistance and low-temperature resistance, and design a polymer meeting any desired object. Therefore, this invention is highly beneficial to related industries and the multi-component copolymer rubber composition of this invention can widely be used in rolls, hoses, packings, seal materials, diaphragms, etc.
The conjugated diolefin which is the component (A") of the nitrile rubber mentioned above includes butadiene, isoprene, etc.
The .alpha.,.beta.-unsaturated nitrile of the component (B") includes acrylonitrile, methacrylonitrile, etc.
The .alpha.,.beta.-unsaturated carboxylic acid ester of the component (C") includes methyl, ethyl, n-butyl and 2-ethylhexyl esters of acrylic and methacrylic acids.
With respect to the component (D"), the carboxyl group-containing monomer includes specifically acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. The epoxy group-containing monomer includes glycidyl (meth)acrylate, glycidyl ether, vinyl glycidyl ehter, etc. The hydroxyl group-containing monomer includes 1-hydroxypropyl (methy)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, etc. The amino group-containing monomer includes dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dibutylaminoethyl (meth)acrylate, etc.
The content of the conjugated diolefin (A") in the nitrile rubber is 20 to 90% by weight. When the content is less than 20% by weight, the rubber is insufficient in low-temperature resistance and mechanical properties. When the content exceeds 90% by weight, the rubber is poor in heat resistance and sour gasoline resistance. The conjugated diolefin (A") in the nitrile rubber may be partially hydrogenated.
The content of the .alpha.,.beta.-unsaturated nitrile (B") in the nitrile rubber is 10 to 55% by weight. When the content is less than 10% by weight, the rubber is poor in oil resistance. When the content exceeds 55% by weight, the rubber is poor in low-temperature resistance.
The content of the .alpha.,.beta.-unsaturated carboxylic acid ester (C") in the nitrile rubber is 0 to 70% by weight. When the content exceeds 70% by weight, the rubber has a low tensile strength.
The content of the monomer (D") in the nitrile rubber is 0 to 20% by weight. When the content exceeds 20% by weight, the rubber has inferior low-temperature resistance or low permanent compression set.
The mixing ratio of the multi-component copolymer rubber of this invention to the nitrile rubber is 20-99 to 80-1 (weight ratio), preferably 50-95 to 50-5. When the proportion of the mixed multi-component copolymer rubber of this invention is less than 20% by weight, the rubber composition is insufficient in heat resistance, sour gasoline resistance and ozone resistance. When the ratio exceeds 99% by weight, the crosslinking reaction of the rubber composition is slow, and the freedom of selection of vulcanizing agent is reduced.
The form of the nitrile rubber used can be either a solid or a liquid as long as its molecular weight is 0.01 dl/g or more in terms of intrinsic viscosity. The form may be a mixture of a solid and a liquid depending upon the application of the rubber composition. When the intrinsic viscosity is lower than 0.01 dl/g, the rubber composition is high in extractability with oil and is not desirable as a gasoline-resistant material. The Mooney vescosity (ML.sub.1+4, 100.degree. C.) of the nitrile rubber is preferably 20 to 80.
The rubber composition of this invention can be kneaded by a conventional mixing equipment such as a roll, a Banbury mixer, an extruder and other intermixers capable of mixing the components without excessively heating.
To the rubber composition of this invention comprising the multi-component copolymer rubber and the nitrile rubber can be added conventional compounding chemicals such as a filler (e.g. carbon black, calcium carbonate, a hydrocarbon resin, a phenolic resin), a vulcanizing agent, a vulcanizing adjuvant, an anti-aging agent, a softener and the like. The vulcanization of the rusulting mixture is usually conducted at 100.degree. to 210.degree. C. for about 0.5 to 120 min with heating by steam, a high temperature liquid or a microwave.
By superimposing a layer consisting of the multi-component copolymer rubber of this invention and a layer consisting of other rubber, a laminate excellent in sour gasoline resistance and sour gasohol resistance can be produced.
The other rubbers include butadiene-acrylonitrile rubber, styrene-butadiene rubber, fluoro-rubber, polychloroprene, acrylic rubber, ethylenepropylene terpolymer (EPT), chlorinated polyethylene, chlorosulfonated polyethylene, silicone rubber, butyl rubber and epichlorohydrin rubber.
The layer consisting of the multi-component copolymer rubber of this invention and/or the layer consisting of the other rubbers may have incorporated thereinto an oxide or hydroxide of a metal of Groups II to IV of the Periodic Table for enhancing bonding strength. The oxide and the hydroxide include metal oxides such as magnesium oxide, aluminum oxide, zinc oxide, zinc dioxide, calcium oxide, lead (divalent and tetravalent) oxides and silicon dioxide and corresponding metal hydroxides. Of these, particularly preferred are magnesium oxide, calcium hydroxide, aluminum hydroxide and lead (divalent) oxide. The amount of the metal oxide or hydroxide added is usually 5 to 30 phr.
To the layer consisting of the multi-component copolymer rubber of this invention and the layer consisting of the other rubbers can be added conventional additives such as a reinforcing agent, a plasticizer, a processing adjuvant, a vulcanizing accelerator, a vulcanizing agent, an anti-aging agent and the like.
According to this invention, the layer consisting of the multi-component copolymer rubber of this invention and/or the layer consisting of the other rubbers may have incorporated thereinto an epoxy resin, a curing agent and a basic substance, and the two layers can be strongly vulcanization-bonded together. The vulcanizing agent may be a combination of maleic anhydride, phthalic anhydride, p-aminodiphenylamine, 2-methylimidazole and the like. The basic substance may be triethylamine, tetrabutylammonium chloride, or the lide. The above-mentioned laminate can also be produced by bonding the above vulcanized layers to one another.
Since the laminate has a thin layer of the multi-component copolymer rubber of this invention excellent in sour gasoline resistance and sour gasohol resistance, the laminate is excellent not only in sour gasoline resistance and sour gasohol resistance but also in various rubber properties. Therefore, the laminate can largely contribute to related industries and be used in rolls, hoses, diaphragms, etc.

Next, this invention will be explained more specifically referring to Examples and the accompanying drawings; however, it should not be interpreted to be restricted to the examples. In the drawings, FIGS. 1 to 3 show infrared absorption spectra of polymers of Examples 1, 10 and 17, respectively. In the Examples and the Comparative Examples, parts are by weight.

EXAMPLES 1 TO 8 AND COMPARATIVE EXAMPLES 1 TO 6
Using the monomers shown in Table 1 and the following polymerization chemicals, polymerization reaction was conducted at 10.degree. C. in an autoclave having an internal volume of 6 liters:
______________________________________Monomers (Details are shown 100 partsin Table 1)Water 200Alkylsulfate type soap 5Potassium phosphate 0.2FeSO.sub.4.7H.sub.2 O 0.006Trisodium salt of 0.020ethylenediaminetetracetic acidSodium formaldehydesulfoxylate 0.08p-Menthane hydroperoxide 0.06______________________________________
When a conversion as shown in Table 1 was reached, 0.2 part, per 100 parts of monomers, of hydroquinone was added to the polymerization system to terminate the polymerization.
Then, the polymerization mixture was heated, and unreacted monomers were removed under reduced pressure. To the residue was added an aqueous calcium chloride solution to coagulate polymer crumbs. The crumbs were water-washed and dried at 50.degree. C. under reduced pressure, to prepare copolymer samples of Examples 1 to 8 and Comparative Examples 1 to 6.
Each copolymer sample was subjected to measurement of Mooney viscosity, copolymer composition and glass transition temperature. The results are shown in Table 1.
The infrared absorption specturm of the polymer of Example 1 is shown in FIG. 1. Since this spectrum has a characteristic absorption of C.tbd.N bond at 2,250 cm.sup.-1 and a characteristic absorption of C.dbd.O bond of ester at 1,730 cm.sup.-1 the presence of these two bonds in the polymer was confirmed. As shown in Table 1, this polymer has a single glass transition temperature (Tg) as measured by differential thermal analysis, which implies that the polymer is a copolymer.
[Test of Characteristics of Vulcanizate]
The copolymer samples shown in Table 1 were subjected to compounding in accordance with the following formulations:
______________________________________[Examples 1, 3, 7 and 8 and Comparative Examples 2, 3and 4](Crosslinking with organic peroxide)Copolymer 100 partsStearic acid 1HAF.sup.(1) carbon black 50Peroximon F40.sup.(2) 2 Note: .sup.(1) High abrasion furnace black .sup.(2) 1,3bis(t-butylperoxyisopropyl) benzene[Examples 2, 4, 5 and 6 and Comparative Examples 1 and 5](Vulcanization with sulfur)Copolymer 100 partsZinc oxide 5Stearic acid 1HAF carbon black 50Accelerator TT.sup.(3) 0.75Sulfur 0.2 Note: .sup.(3) Tetramethylthiuram disulfide[Comparative Example 6](Butadiene-acrylonitrile rubber)Copolymer 100 partsZinc oxide 5Stearic acid 1SRF.sup.(4) carbon black 60DOP.sup.(5) 5 partsAccelerator TT.sup.(6) 1.5Accelerator CZ.sup.(7) 2Sulfur 0.5______________________________________ Note: .sup.(4) Semireinforcing furnace black .sup.(5) Dioctyl phthalate .sup.(6) Tetramethylthiuram disulfide .sup.(7) N--cyclohexyl2-benzothiazolsulfenamide
The compounds obtained were subjected to presscuring (at 180.degree. C. for 20 min for Examples 1, 3, 7 and 8 and Comparative Examples 2, 3 and 4; at 170.degree. C. for 20 min for Examples 2, 4, 5 and 6 and Comparative Examples 1 and 5; and at 160.degree. C. for 20 min for Comparative Example 6) to obtain crosslinked rubbers.
Each crosslinked rubber was subjected to measurement of characteristics in accordance with JIS K 6301. The rubber was also subjected to measurement of sour gasoline resistance in accordance with the following test method.
[Test Method for Sour Gasoline Resistance]
A vulcanized rubber was immersed at 70.degree. C. for 24 hr in a solution obtained by dissolving 1 g of lauryl peroxide in 99 g of Fuel C (a mixed solvent of isooctane:toluene=1:1 by volume). This 1 cycle procedure was repeated 20 times (20 cycles). Then, the rubber was dried at 100.degree. C. for 15 hr under reduced pressure and subjected to measurment of tensile strength and elongation at break in accordance with JIS K 6301. The changes of these properties after immersion compared with those before immersion were calculated and used as criteria of the sour gasoline resistance of the rubber. The results are shown in Table 1.
As is obvious from Table 1, each of the multi-component copolymer rubbers of this invention provides a crosslinked material which is excellent in gasoline resistance, sour gasoline resistance, heat resistance and ozone resistance, good in low-temperature resistance, tensile strength and elongation and small in permanent compression set.
TABLE 1__________________________________________________________________________ Example Comparative Example 1 2 3 4 5 6 7 8 1 2 3 4 5 6__________________________________________________________________________Monomers fed, parts Buta-Component (A) diene2-Cyanoethyl acrylate 55 45 35 25 25 45 73 12 10 acrylo-4-Cyanobutyl acrylate 50 40 75 13 nitrileComponent (B) rubberEthyl acrylate 30 60 53 47 57 85 22 84 (Acry-Butyl acrylate 42 52 32 12 12 52 24 24 62 loni-Component (C) trileEthylidenenorbornene 3 3 3 3 3 3 3 3 3 3 3 con-Dihydrodicyclopentadienyl tent:acrylate 1 41% byComponent (D) weight)Methoxyethyl acrylate 7 25Conversion, % 84 87 80 89 90 92 78 81 83 88 82 90 85Mooney viscosity:ML.sub.1+4 100.degree. C. 56 50 52 46 42 48 41 43 60 49 40 34 33Copolymer composition, %*.sup.12-Cyanoethyl acrylate 56 47 35 26 26 45 73 14 104-Cyanobutyl acrylate 51 39 73 16Ethyl acrylate 31 59 53 46 58 83 24 81Butyl acrylate 41 50 31 12 12 51 24 62Ethylidenenorbornene 3 3 3 3 3 3 3 3 3 3 3 3Dihydrodicyclopentadienyl 0 2acrylateMethoxyethyl acrylate 6 0 25Glass transition temperature -20 -27 -24 -20 -22 -28 -28 -27 -7 -16 -33 -22 -41 -22Tg, .degree.C.Kind of crosslinking agent*.sup.2 PO S PO S S S PO PO S PO PO PO S SProperties of crosslinkedrubberTensile strength, kg/cm.sup.2 145 129 139 124 122 120 134 121 97 123 88 94 81 196Elongation, % 350 490 400 510 490 320 470 530 190 490 160 570 580 520Hardness, JIS-A 74 72 70 68 68 73 66 64 81 67 69 63 55 73Gasoline resistance (After 40.degree. C. .times. 48 hr immersion in FuelC).DELTA.V, % +26 +34 +37 +44 +39 +36 +38 +43 +5 +61 +30 +102 +119 +41Sour gasoline resistance (After immersion of 70.degree. C. .times. 24 hr.times. 20 cycles inFuel C containing 1% of lauryl peroxide)Change of tensile -11 -13 -22 -31 -39 -12 -25 -26 -10 -79 -16 -95 -76 -87strength, %Change of elongation, % -17 -31 -35 -12 -33 -24 -39 -46 -15 +32 -21 -72 -88 -96Heat resistance (150.degree. C. .times. 72 hr aging with air heating)Change of tensile +4 -7 +2 -3 -8 -10 -15 -11 -12 +6 -9 +13 -45 -81strength, %Change of elongation, % -23 -52 -24 -37 -41 -58 -29 -23 -56 -20 -32 -26 -67 -100 (No elongation)Change of hardness, +9 +12 +11 +10 +11 +12 +14 +12 +15 +8 +13 +11 +13 +23JIS-AOzone resistance, (500 pphm, .rarw. No cracking for 168 hr .fwdarw. Cracks40.degree. C., 30% elongation) appear- ed in 2 hrLow-temperature resistance:Gehman torsion test T100, .degree.C. -19 -25 -22 -18 -20 -27 -25 -25 -4 -14 -29 -20 -38 -20Permanent compression set, 19 50 24 54 57 42 22 23 47 28 20 26 70 65150.degree. C. .times. 70 hr, %__________________________________________________________________________ *.sup.1 Analysis of copolymer components Component (A) Calculated from the nitrogen content measured by Kjeldahl method. Components (B) and (D) Calculated from the unreacted monomer amount in polymerization system measured by gas chromatography, using the following formula: ##STR4## yi: % of component i in copolymer ai: Amount of component i fed bi: Amount of component i unreacted A: Amount of total monomers fed x: Conversion Component (C) Measured by iodometry. *.sup.2 PO: Crosslinking by an organic peroxide S: Vulcanization by sulfur
EXAMPLES 9 TO 14 AND COMPARATIVE EXAMPLES 7 TO 11
The copolymer samples of Examples 9 to 14 and Comparative Examples 7 to 11 were prepared by repeating the procedure of Examples 1 to 8, except that the monomers shown in Table 2 were used.
Each copolymer sample was subjected to measurement of Mooney viscosity, copolymer composition and glass transition temperature. The results are shown in Table 2.
The infrared absorption spectrum of the polymer of Example 10 is shown in FIG. 2. Since this spectrum has a characteristic absorption of C.tbd.N bond at 2,250 cm.sup.-1 and a characteristic absorption of C.dbd.O bond of ester at 1,730 cm.sup.-1, the presence of these two bonds in the polymer was confirmed. As shown in Table 2, this polymer has a single glass transition temperature (Tg) as measured by differential thermal analysis, which implies that the polymer is a copolymer.
[Test of Characteristics of Vulcanizate]
The copolymer samples shown in Table 2 were subjected to compounding in accordance with the following formulations.
______________________________________(Examples 9 to 14 and Comparative Examples 7 to 9)Copolymer 100 partsStearic acid 1HAF.sup.(1) carbon black 50Ammonium benzoate 1 Note: .sup.(1) High abrasion furnace black(Comparative Example 10)Copolymer 100 partsStearic acid 1HAF carbon black 50Accelerator TRA.sup.(2) 0.5Accelerator EUR.sup.(3) 1Calcium stearate 3 Note: .sup.(2) Dipentamethylenethiuram hexasulfide .sup.(3) 1,3-Diethylthiourea(Comparative Example 11)(Butadiene-acrylonitrile rubber)Copolymer 100 partsZinc oxide 5Stearic acid 1SRF.sup.(4) carbon black 60DOP.sup.(5) 5Accelerator TT.sup.(6) 1.5Accelerator CZ.sup.(7) 2Sulfur 0.5______________________________________ Note: .sup.(4) Semi-reinforcing furnace black .sup.(5) Dioctyl phthalate .sup.(6) Tetramethylthiuram disulfide .sup.(7) N--cyclohexyl-2-benzothiazolsulfenamide
The compounds obtained were subjected to press-curing (at 175.degree. C. for 20 min for Examples 9 to 14 and Comparative Examples 7 to 10 and at 160.degree. C. for 20 min for Comparative Example 11) to obtain crosslinked rubbers.
Each crosslinked rubber was subjected to measurement of characteristics in accordance with JIS K 6301. The rubber was also subjected to measurement of sour gasoline resistance in accordance with the same method as in Examples 1 to 8. The results are shown in Table 2.
As is obvious from Table 2, each of the multi-component copolymer rubbers of this invention provides a crosslinked material which is excellent in gasoline resistance, sour gasoline resistance, heat resistance and ozone resistance, good in low-temperature resistance, tensile strength and elongation and small in permanent compression set.
TABLE 2__________________________________________________________________________ Example Comparative Example 9 10 11 12 13 14 7 8 9 10 11__________________________________________________________________________Monomers fed, parts Butadiene-Component (A) acrylo-2-Cyanoethyl acrylate 45 35 35 25 75 10 20 nitrile4-Cyanobutyl acrylate 60 40 75 rubberComponent (B) (Acrylo-Ethyl acrylate 30 30 47 37 57 22 52 nitrilen-Butyl acrylate 52 32 27 25 22 62 25 content:Component (C) 41% byAllyl glycidyl ether 3 3 3 3 3 3 3 3 weight)Glycidyl methacrylate 3Component (D)Vinyl chloroacetate2-Methoxyethyl acrylate 5 25Conversion, % 77 83 86 91 81 85 79 88 74 85Mooney viscosity, ML.sub.1+4, 100.degree. C. 41 44 45 50 36 39 57 37 35 42Copolymer composition, %*.sup.12-Cyanoethyl acrylate 46 36 35 25 76 10 214-Cyanobutyl acrylate 61 41 76Ethyl acrylate 30 30 48 36 56 21 21 52n-Butyl acrylate 51 31 25 24 64 25Allyl glycidyl ether 3 3 3 3 3 3 3Glycidyl methacrylate 4Vinyl chloroacetate 22-Methoxyethyl acrylate 6 23Glass transition temperature: -30 -26 -25 -26 -35 -31 -9 -46 -35 -26 -22Tg, .degree.C.Properties of crosslinkedrubberTensile strength, kg/cm.sup.2 142 157 138 164 133 120 102 95 116 144 196Elongation, % 450 360 300 420 490 530 110 570 170 480 520Hardness, JIS-A 68 68 70 66 66 63 81 51 69 62 73Gasoline resistance (After immersion in Fuel C at 40.degree. C. for 48hr).DELTA.V, % +33 +39 +36 +47 +35 +45 +4 +121 +27 +58 +41Sour gasoline resistance (After immersion of 70.degree. C. .times. 24 hr.times. 20 cycles inFuel C containing 1% of lauroyl peroxide) -Change of tensile -18 -28 -26 -41 -17 -19 -6 -72 -13 -91 -87strength, %Change of elongation, % -38 -38 -47 -11 -22 -37 -17 -86 -15 -72 -96Heat resistance (150.degree. C. .times. 72 hr aging with air heating)Change of tensile +3 +6 -11 -2 -14 -8 -10 -39 -20 +2 -81strength, %Change of elongation, % -44 -34 -46 -23 -49 -43 -51 - 60 -55 -22 -100 (No elongation)Change of hardness, JIS-A +13 +12 +13 +9 +15 +13 +14 +15 +18 +7 +23Ozone resistance, (500 pphm, .rarw. No cracking for 168 hr .fwdarw. Cracks40.degree. C., 30% elongation) appeared in 2 hrLow-temperature resistance:Gehman torsion test T100, .degree.C. -28 -24 -24 -25 -33 -28 -6 -41 -30 -23 -20Permanent compression set, 44 48 51 52 50 54 27 67 46 64 65150.degree. C. .times. 70 hr, %__________________________________________________________________________ *.sup.1 Analysis of copolymer components Cyanoalkyl acrylates: Calculated from the nitrogen content measured by Kjeldahl method. Alkyl acrylates and other monomers: Calculated from the unreacted monomer amount in polymerization system measured by gas chromatography, using the following formula. ##STR5## yi: % of component i in copolymer ai: Amount of component i fed bi: Amount of component i unreacted x: Conversion
EXAMPLES 15 TO 19 AND COMPARATIVE EXAMPLES 12 TO 17
The copolymer samples of Examples 15 to 19 and Comparative Examples 12 to 17 were prepared by repeating the procedure of Examples 1 to 8, except that the monomers shown in Table 3 were used.
Each copolymer sample was subjected to measurement of Mooney viscosity, copolymer composition and glass transition temperature. The results are shown in Table 3.
The infrared absorption spectrum of the copolymer of Example 17 is shown in FIG. 3. Since this spectrum has a characteristic absorption of C.tbd.N bond at 2,250 cm.sup.-1 and a characteristic absorption of C.dbd.O bond of ester at 1,730 cm.sup.31 1, the presence of these two bonds in the copolymer was confirmed. As shown in Table 3, this copolymer has a single glass transition temperature (Tg) as measured by differential thermal analysis, which implies that the product is a copolymer.
[Test of Characteristics of Vulcanizate]
The copolymer samples shown in Table 2 were subjected to compounding in accordance with the following formulations.
[Examples 15 to 19 and Comparative Examples 12 to 16]
The same formulation as in Comparative Example 10.
[Comparative Example 17]
The same formulation as in Comparative Example 11.
The compounds obtained were subjected to press-curing (at 175.degree. C. for 20 min for Examples 15 to 19 and Comparative Examples 12 to 16 and at 160.degree. C. for 20 min for Comparative Example 17) to obtain crosslinked rubbers.
Each crosslinked rubber was subjected to measurement of characteristics in accordance with JIS K 6301. The rubber was also subjected to measurement of sour gasoline resistance in accordance with the same method as in Examples 1 to 8.
As is obvious from Table 3, each of the multi-component copolymer rubbers of this invention provides a crosslinked material which is excellent in gasoline resistance, sour galosine resistance, heat resistance and ozone resistance, good in low temperature resistance, tensile strength and elongation and small in permanent compression set.
TABLE 3__________________________________________________________________________ Example Comparative Example 15 16 17 18 19 12 13 14 15 16 17__________________________________________________________________________Monomers fed, parts Butadiene-Cyano-substituted alkyl acrylo-acrylates nitrile2-Cyanoethyl acrylate 55 35 45 73 10 0.5 rubber4-Cyanobutyl acrylate 50 40 75 20 (Acrylo-Alkyl acrylates nitrileEthyl acrylate 30 47 57 22 77 20.5 content:Butyl acrylate 42 32 52 24 62 78 41% byOther comonomers weight)Vinylbenzyl chloride 3 3 3 3Vinyl chloroacetate 3 3 3 3 3 1Methoxyethyl acrylate 25Conversion, % 86 81 81 88 85 78 88 82 84 83Mooney viscosity, ML.sub.1+4, 100.degree. C. 47 42 49 37 40 54 36 33 31 2.9Copolymer composition, %*.sup.12-Cyanoethyl acrylate 55 35 47 74 11 0.54-Cyanobutyl acrylate 53 42 74 20Ethyl acrylate 31 45 56 24 78 21.5Butyl acrylate 42 32 51 23 61 77Vinylbenzyl chloride 3 2 3 3Vinyl chloroacetate 2 2 2 25 2 2Methoxyethyl acrylate 1Glass transition temperature: -20 -24 -28 -31 -29 -10 -43 -35 -25 -46 -22Tg, .degree.C.Properties of crosslinkedrubberTensile strength, kg/cm.sup.2 159 145 164 151 138 109 86 121 117 56 196Elongation, % 290 410 460 480 550 130 540 180 620 610 520Hardness, JIS-A 70 64 66 65 63 77 52 68 61 50 73Gasoline resistance (After immersion in Fuel C at 40.degree. C. for 48hr).DELTA.V, % +28 +42 +35 +38 +44 +4 +117 +29 +85 +190 +41Sour gasoline resistance (After immersion of 70.degree. C. .times. 24 hr.times. 20 cycles inFuel C containing 1% of lauroyl peroxide)Change of tensile -21 -32 -23 -29 -29 -8 -83 -14 -94 Impos- -87strength, % sibleChange of elongation, % -32 -45 -26 -39 -44 -20 -85 -21 -67 to measure -96 due to high soft- nessHeat resistance (150.degree. C. .times. 72 hr aging with air heating)Change of tensile -6 +1 -4 -16 -10 +23 -41 -21 +25 +11 -81strength, %Change of elongation, % -44 -38 -47 -47 -39 -51 -63 -54 -30 -24 -100 (No elongation)Change of hardness, JIS-A +8 +13 +10 +15 +14 +18 +14 +19 +9 +8 +23Ozone resistance (500 pphm, .rarw. No cracking for 168 hr .fwdarw. Cracks40.degree. C., 30% elongation) appeared in 2 hrLow-temperature resistance:Gehman torsion test T100, .degree.C. -17 -22 -25 -29 -26 -7 -37 -31 -22 -42 -20Permanent compression set, 49 56 53 52 55 42 68 47 62 57 65150.degree. C. .times. 70 hr, %__________________________________________________________________________ *.sup.1 Analysis of copolymer components Cyanoalkyl acrylates: Calculated from the nitrogen content measured by Kjeldahl method. Alkyl acrylates and other monomers: Calculated from the unreacted monomer amount in polymerization system measured by gas chromatography, using the following formula: ##STR6## yi: % of component i in copolymer ai: Amount of component i fed bi: Amount of component i unreacted x: Conversion
EXAMPLES 20 TO 25 AND COMPARATIVE EXAMPLE 18
The copolymers shown in Table 4 were subjected to compounding in accordance with the formulations shown in Table 5 and kneaded by a roll to obtain unvulcanized rubber compounds. These unvulcanized rubber compounds were subjected to press-curing (at 175.degree. C. for 20 min for Examples 20 to 25 and at 160.degree. C. for 20 min for Comparative Example 18) to obtain vulcanized rubbers. The vulcanized rubbers were subjected to measurement of characteristics in accordance with JIS K 6301. The rubbers were also subjected to measurement of sour gasoline resistance by the same method as in Examples 1 to 8.
As is obvious from Table 4, the vulcanized rubber compositions of this invention ar excellent in sour gasoline resistance and heat resistance and good in tensile strength and elongation.
TABLE 4__________________________________________________________________________ Comparative Example Example 20 21 22 23 24 25 18__________________________________________________________________________Copolymer composition, %*.sup.1 Butadiene- -2-Cyanoethyl acrylate 57 46 36 47 acrylonitrile4-Cyanoethyl acrylate 53 42 rubberEthyl acrylate 30 45 56 (Acrylonit-Butyl acrylate 40 51 31 51 rile content:Allyl glycidyl ether 3 3 3 41% by weight)Vinyl chloroacetate 2 2 2Crosslinking agents, partsHexamethylenetetramine 0.5Zinc dimethyldithiocarbamate 0.3Potassium stearate 2.5 0.5Sodium stearate 1 2.5Sulfur 0.2 0.3Ammonium benzoate 3Hexamethylenediamine carbamate 0.5Properties of crosslinked rubberTensile strength, kg/cm.sup.2 160 138 165 171 160 141 196Elongation, % 300 470 380 450 430 560 520Hardness, JIS-A 70 67 68 67 64 62 73Sour gasoline resistance (After immersion of 70.degree. C. .times. 24 hr.times. 20 cycles in Fuel C containing 1% of lauroyl peroxide)Change of tensile strength, % -13 -20 -25 -17 -30 -27 -87Change of elongation, % -25 -39 -40 -22 -37 -41 -96Heat resistance (150 .degree. C. .times. 72 hr aging with air heating)Change of tensile strength, % -5 +2 +5 +2 -7 -8 -81Change of elongation, % -43 -45 -30 -41 -46 -43 -100 (No elongation)Change of hardness, JIS-A +12 +13 +10 +10 +11 +14 +23__________________________________________________________________________ *.sup.1 Analysis of copolymer components Cyanoalkyl acrylates: Calculated from the nitrogen content measured by Kjeldahl method. Alkyl acrylates and other monomers: Calculated from the unreacted monomer amount in polymerization system meausred by gas chromatography, using the following formula: ##STR7## yi: % of component i in copolymer ai: Amount of component i fed bi: Amount of component i unreacted x: Conversion
TABLE 5______________________________________Compound formulation______________________________________Examples 20 to 25Polymer 100 partsHAF carbon black 50Stearic acid 1Crosslinking agent Shown in Table 1Comparative Example 18Polymer 100 partsZinc oxide 5Stearic acid 1SRF carbon black 60DOP 5Vulcanization accelerator TT*.sup.1 1.5Vulcanization accelerator CZ*.sup.2 2Sulfur 0.5______________________________________ *.sup.1 Tetramethylthiuram disulfide *.sup.2 N--cyclohexyl-2-benzothiazolsulfenamide
EXAMPLES 26 TO 34 AND COMPARATIVE EXAMPLES 19 TO 23
Using the monomers shown in Table 7 and the following polymerization chemicals, polymerization reaction was conducted at 10.degree. C. in an autoclave having an internal volume of 6 liters:
______________________________________Monomers (Details are shown in 100 partsTable 7)Water 200Alkylsulfate type soap 5Potassium phosphate 0.2FeSO.sub.4.7H.sub.2 O 0.006Trisodium salt of 0.020ethylenediaminetetracetic acidSodium formaldehydesulfoxylate 0.08p-Menthane hydroperoxide 0.06______________________________________
When a conversion shown in Table 7 was obtained, 0.2 part of hydroquinone per 100 parts of monomers was added to the polymerization system to terminate the polymerization.
Then, the polymerization mixture was heated, and the unreacted monomers were removed under reduced pressure. To the residue was added an aqueous calcium chloride solution to coagulate polymer crumbs. The crumbs were water-washed and dried at 50.degree. C. under reduced pressure, whereby the copolymers of Examples 26 to 34 and Comparative Examples 19 to 23 were prepared. These copolymers were compounded with the formulations show in Table 6 and kneaded by a Banbury mixer. The kneaded compounds were subjected to evaluation of processability from dischargability from Banbury mixer as well as from knitting performance, and good processability was indicated as o, and bad processability as X.
The compounded rubbers obtained were subjected to press-curing at 175.degree. C. for 20 min to obtain vulcanized rubbers. The vulcanized rubbers were subjected to measurement of characteristics in accordance with JIS K 6301. These rubbers were also subjected to measurement of sour gasoline resistance in accordance with the following method.
[Test Method for Sour Gasoline Resistance]
A vulcanized rubber was immersed at 70.degree. C. for 24 hr in a solution obtained by dissolving 1 g of lauryl peroxide in 99 g of Fuel C (a mixed solvent of isooctane: toluene=1:1 by volume). This 1 cycle procedure was repeated 20 times (20 cycles). Then, the rubber was dried at 100.degree. C. for 15 hr under reduced pressure and subjected to measurement of tensile strength and elongation in accordance with JIS K 6301. The change (%) of the value obtained after immersion relative to the value obtained before immersion was calculated and used as criteria of the sour gasoline resistance of the rubber. The results are shown in Table 7.
As is obvious from Table 7, the multi-component copolymer rubbers of this invention have good kneadability and the vulcanized rubbers obtained therefrom are excellent in sour gasoline resistance and heat resistance and good in tensile strength and elongation.
TABLE 6__________________________________________________________________________ A B C D E F G H I J__________________________________________________________________________Copolymer 100 100 100 100 100 100 100 100 100 100Stearic acid 1 1 5 1 1 1 1 1 1 1HAF carbon black 50 50 50 50 50 50 50 50 50 50Ammonium benzoate 1 1 1 1 1 1 1 1 1 1TE-80*.sup.1 3 1 0.2 15 3Paraffin wax*.sup.2 5VANFRE AP-2*.sup.3 3GAFAC RL210*.sup.4 3RS 700*.sup.5 5__________________________________________________________________________ *.sup.1 Sodium salt of a fatty acid, manufactured by Du Pont *.sup.2 Hydrocarbon type compound *.sup.3 Fatty acid ester type compound, manufactured by IPPOSHA OIL INDUSTRY CO., LTD. *.sup.4 Phosphoric acid ester type compound, manufactured by Toho Chemica Industries Co., Ltd. *.sup.5 Polyetherester compound (plasticizer)
TABLE 7__________________________________________________________________________ Example Comparative Example Example 26 27 28 29 30 31 32 33 19 20 21 22 23 34__________________________________________________________________________Monomers fed, partsComponent (A)2-Cyanoethyl acrylate 45 35 45 45 45 45 45 45 45 45 35 454-Cyanobutyl acrylate 60 60Component (B)Ethyl acrylate 30 37 30 37n-Butyl acrylate 52 27 52 52 52 52 52 52 52 52 27 52Component (C)Allyl glycidyl ether 3 3 3 3 3 3 3 3 3 3 3 3Glycidyl methacrylate 3 3Component (D)Vinyl chloroacetate2-Methoxyethyl acrylate 5 5Conversion, % 77 86 81 77 77 77 77 77 77 77 77 86 81 77Mooney viscosity, ML.sub.1+4, 100.degree. C. 41 45 36 41 41 41 41 41 41 41 41 45 36 41Copolymer composition, %*.sup.12-Cyanoethyl acrylate 46 35 46 46 46 46 46 46 46 46 35 464-Cyanobutyl acrylate 61 61Ethyl acrylate 30 36 30 36n-Butyl acrylate 51 25 51 51 51 51 51 51 51 51 25 51Allyl glycidyl ether 3 3 3 3 3 3 3 3 3 3 3 3Glycidyl methacrylate 4 4Vinyl chloroacetate2-Methoxyethyl acrylate 6 6Glass transition temperature: -30 -25 -35 -30 -30 -30 -30 -30 -30 -30 -30 -25 -35 -30Tg, .degree.C.Compound formulation A A A B C D E F G H I I I JProcessability o o o o o o o o x o x x x oProperties of crosslinkedrubberTensile strength, kg/cm.sup.2 138 132 130 140 137 139 138 120 142 85 142 138 133 130Elongation, % 460 330 520 450 470 480 480 530 450 610 450 300 490 500Hardness, JIS-A 66 67 65 67 68 67 67 65 68 58 68 70 66 63Gasoline resistance (After immersion of 40.degree. C. .times. 48 hr inFuel C).DELTA.V, % +26 +30 +28 +30 +30 +31 +30 +28 +31 +23 +33 +36 +35 +21Sour gasoline resistance (After immersion of 70.degree. C..times. 24 hr.times. 20 cycles in Fuel C containing 1% of lauroyl peroxide)Change of tensile -14 -19 -15 -17 -20 -15 -14 -20 -17 -23 -18 -26 -17 -10strength, %Change of elongation, % -35 -35 -25 -39 -40 -35 -40 -42 -40 -45 -38 -47 -22 -32Heat resistance (150.degree. C. .times. 72 hr aging with air heating)Change of tensile -1 -7 -10 -2 -5 -5 -7 -1 +2 -7 +3 -1 -14 +5strength, %Change of elongation, % -48 -48 -51 -43 -46 -48 -48 -47 -45 -51 -44 -46 -49 -50Change of hardness, JIS-A +15 +15 +17 +14 +14 +14 +14 +15 +13 +18 +13 +13 +15 +17Ozone resistance (50 pphm, 40.degree. C., 30% elongation) .rarw. No cracking for 168 hr .fwdarw.Low-temperature resistance: -30 -25 -35 -29 -29 -29 -29 -30 -28 -33 -28 -24 -33 -36Gehman torsion testT100, .degree.C.Permanent compression set, 45 52 52 44 45 46 45 46 44 54 44 51 50 47150.degree. C. .times. 70 hr, %__________________________________________________________________________ *.sup.1 Analysis of copolymer coponents Component (A) Calculated from the nitrogen content measured by Kjeldhl method. Components (B) and (C) Calculated from the unreacted monomer amount in polymerization system measured by gas chromatography, using the following formula: ##STR8## yi: % of component i in copolymer ai: Amount of component i fed bi: Amount of component i unreacted A: Amount of total monomers fed x: Conversion Component (C) Measured by iodometry.
EXAMPLES 35 TO 42 AND COMPARATIVE EXAMPLES 24 TO 28
Each polymer composition sample consisting of a multi-component copolymer rubber and a fluororubber whose formulation is shown in the upper section of Table 9 was compounded by a Banbury mixer with the formulation shown in Table 8. Each compound obtained was press-cured under the conditions shown in the lower section of Table 8.
The crosslinked rubber compositions thus obtained were subjected to measurement of characteristics in accordance with JIS K 6301.
These rubber compositions were also subjected to sour gasoline resistance and sour gasohol resistance in accordance with the following method.
[Test Method for Sour Gasoline Resistance]
A test specimen of a crosslinked rubber composition was immersed at 40.degree. C. for 72 hr in a solution obtained by dissolving 2.5 g of lauryl peroxide in 97.5 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene). This 1 cycle procedure was repeated n times (n cycles). After each cycle, the test specimen was taken out, dried at 100.degree. C. for 15 hr under reduced pressure and bent at an angle of 180.degree. to observe formation of cracks.
[Test Method for Sour Gasohol Resistance]
This resistance was measured by the same method as in the case of sour gasoline resistance, except that Fuel C was replaced by a mixed solvent consisting of 80 parts by volume of Fuel C and 20 parts by volume of ethanol.
The measurement results are shown in the lower section of Table 9.
As is obvious from Table 9, the multi-component copolymer rubber compositions of this invention are excellent not only in gasoline resistance, gasohol resistance, sour gasoline resistance, sour gasohol resistance, ozone resistance and heat resistance but also in tensile strength, elongation and balance between gasoline resistance and low-temperature resistance.
TABLE 8__________________________________________________________________________ Compound Symbol K L M N O__________________________________________________________________________Polymer composition 100.0 100.0 100.0 100.0 100.0Zinc oxide 5.0Stearic acid 1.0 1.0 1.0 1.0 1.0HAF carbon black*.sup.1 20.0 20.0 20.0 20.0 60.0Processing aid TE-80*.sup.2 1.0 1.0 1.0 1.0 1.0Accelerator TT*.sup.3 0.75Accelerator TRA*.sup.4 0.5Accelerator EUR*.sup.5 1.0Sulfur 0.2Peroximon F40*.sup.6 2.0Ammonium benzoate 2.0 2.0Potassium stearate 3.0Conditions for press-curing 165.degree. C. .times. 180.degree. C. .times. 165.degree. C. .times. 175.degree. C. .times. 165.degree. C. .times. 30 min 20 min 30 min 20 min 30 min__________________________________________________________________________ *.sup.1 High abrasion furnace black *.sup.2 Metal salt of a fatty acid, manufactured by Technical Processing Co. *.sup.3 Tetramethylthiuram disulfide *.sup.4 Dipentamethylenethiuram hexasulfide *.sup.5 1,3-Diethylthiourea *.sup.6 1,3-Bis(t-butylperoxyisopropyl)benzene
TABLE 9__________________________________________________________________________ Example Comparative Example 35 36 37 38 39 40 41 42 24 25 26 27 28__________________________________________________________________________Multi-component copolymer 70 70 70 70 70 70 90 50 70 70 97 70 28rubber, partsComponent (A) composition (%)2-Cyanoethyl acrylate 56 35 25 25 25 25 25 86 25 25 254-Cyanobutyl acrylate 42Component (B) composition (%)Ethyl acrylate 31 53 47 56 47 47 47 97 47 47 47n-Butyl acrylate 41 31 12 25 25 25 25 11 25 25 25Component (C) composition (%)Ethylidenenorbornene 3 3 3 3 3Allyl glycidyl ether 3 3 3 3 3 3Vinyl chloroacetate 2 3Component (D) composition (%)Methoxyethyl acrylate 7Fluororubber, partsJSR KYNAR 731*.sup.1 30 30 30 30 30 10 50 30 30 3VITON GF*.sup.2 30JSR AFLAS*.sup.3 30Compound symbol*.sup.4 K L K M N O M M K K O O MProperties of crosslinked rubberTensile strength, kg/cm.sup.2 210 202 198 195 193 155 165 240 185 121 151 150 150Elongation, % 250 265 270 265 275 350 320 190 255 150 350 370 350Hardness, JIS-A 71 70 69 72 71 72 65 75 72 75 66 73 66Gasoline resistance (After immersion of 40.degree. C. .times. 48 hr inFuel C).DELTA.V, % +8 +15 +27 +32 +41 +35 +45 +25 +105 +3 +48 +60 +49Gasohol resistance (After immersion of 40.degree. C. .times. 48 hr in asolution ofFuel C/ethanol = 80/20).DELTA.V, % +26 +35 +55 +67 +67 +80 +85 +49 +150 +11 +130 +97 +132Sour gasoline resistance (After immersion of 40.degree. C. .times. 72 hr.times. n cycles inFuel C containing 2.5% of lauroyl peroxide)n.times.3 (3 cycles) NC*.sup.5 NC NC NC NC NC NC NC Soft- NC NC NC NC enedn.times.10 (10 cycles) NC NC NC NC NC NC NC NC Soft- NC NC NC NC enedSour gasohol resistance (After immersion of 40.degree. C. .times. 72 hr.times. n cycles in a solutionconsisting of 80 volume % of Fuel C containing 2.5% of lauroyl peroxideand20 volume % of ethanol)n.times.3 (3 cycles) NC NC NC NC NC NC NC NC Soft- NC NC NC NC enedn.times. 6 (6 cycles) NC NC NC NC NC NC NC NC Soft- NC NC NC NC enedn.times.10 (10 cycles) NC NC NC NC NC NC NC NC Soft- NC NC NC NC enedHeat resistance (150.degree. C. .times. 72 hr aging with air heating)Change of tensile strength, % +3 +1 +6 +5 +2 +5 +10 +1 +12 +1 +11 +5 +12Change of elongation, % -40 -31 -19 -22 -23 -38 -45 -19 -16 -80 -59 -45 -59Change of hardness, JIS-A +6 +5 +3 +2 +4 +10 +4 +3 +5 +18 +5 +12 +6Ozone resistance, static (80 pphm, 40.degree. C., 100% elongation)24 hr NC NC NC NC NC NC NC NC NC NC NC NC NCOzone resistance, dynamic (80 pphm, 40.degree. C., 0 to 20% elongation)24 hr NC NC NC NC NC NC NC NC NC NC NC NC NC288 hr NC NC NC NC NC NC NC NC NC NC NC NC NCLow-temperature resistance:Gehman torsion test T100, .degree.C. -23 -25 -24 -31 -32 -21 -27 -35 -15 -5 -24 -19 -24__________________________________________________________________________ *.sup.1 Poly(vinylidene fluoride), manufactured by Penwalt Co. *.sup.2 Vinylidene fluoride type fluororubber, manufactured by Du Pont *.sup.3 Tetrafluoroethylene-propylene type fluororubber, manufactured by Asahi Glass Co., Ltd. *.sup.4 Refer to Table 8. *.sup.5 No cracking
EXAMPLES 43 TO 47 AND COMPARATIVE EXAMPLES 29 TO 31
Each sample of multi-component copolymer rubber/vinyl chloride resin (hereinafter referred to as PVC) compositions (Examples 43 to 47 and Comparative Examples 29 to 30) and a butadiene-acrylonitrile rubber (hereinafter referred to as NBR)/PVC composition (Comparative Example 31) was compounded by a Banbury mixer in accordance with the formulation shown in Table 10. Each compound obtained was press-cured under the conditions shown in the lower section of Table 10.
The crosslinked rubber compositions obtained were subjected to measurement of characteristics in accordance with JIS K 6301.
These compositions were also subjected to measurement of sour gasoline resistance and sour gasohol resistance in the same methods as in Examples 35 to 42, except that methanol was substituted for the ethanol.
The measurement results are shown in the lower part of Table 11.
As is obvious from Table 11, the multi-component copolymer rubber compositions of this invention are excellent not only in sour gasoline resistance, sour gasohol resistance, ozone resistance and heat resistance but also in tensile strength, elongation and balance between gasoline resistance and low-temperature resistance.
EXAMPLES 48 TO 52 AND COMPARATIVE EXAMPLE 32
There were prepared compositions each consisting of the same copolymer (2-cyanoethyl acrylate/ethyl acrylate/n-butyl acrylate/ethylidenenorbornene=35/31/31/3 by weight) and the same PVC but having a different formulation. These compositions were compounded by a Banbury mixer with the formulations shown in the upper section of Table 12.
The crosslinked rubber compositions obtained were subjected to measurement of characteristics by the same methods as in Example 43. The results are shown in the lower part of Table 12.
As is obvious from Table 12, the multi-component copolymer rubber compositions of this invention are excellent in sour gasoline resistance and sour gasohol resistance, good in tensile strength and elongation and has a practically satisfactory level of a permanent compression set.
TABLE 10__________________________________________________________________________ Compound symbol P Q R S T__________________________________________________________________________Polymer 100.0 100.0 100.0 100.0 100.0Zinc oxide 5.0 5.0Stearic acid 1.0 1.0 1.0 1.0 1.0SRF carbon black*.sup.1 50.0 50.0 50.0 50.0 30.0DOP*.sup.2 5.0 5.0 5.0 5.0 5.0Accelerator TT*.sup.3 0.75 1.5Accelerator CZ*.sup.4 2.0Accelerator TRA*.sup.5 0.5Accelerator EUR*.sup.6 1.0Sulfur 0.2 0.5Peroximon F40*.sup.7 2.0Ammonium benzoate 1.0Potassium stearate 3.0Conditions for press-curing 170.degree. C. .times. 180.degree. C. .times. 175.degree. C. .times. 175.degree. C. .times. 160.degree. C. .times. 20 min 20 min 20 min 20 min 20 min__________________________________________________________________________ *.sup.1 Semi-reinforcing furnace black *.sup.2 Dioctyl phthalate *.sup.3 Tetramethylthiuram disulfide *.sup.4 N--cyclohexyl-2-benzothiazolsulfenamide *.sup.5 Dipentamethylenethiuram hexasulfide *.sup.6 1,3-Diethylthiourea *.sup.7 1,3-Bis(t-butylperoxyisopropyl)benzene
TABLE 11__________________________________________________________________________ Example Comparative Example 43 44 45 46 47 29 30 31__________________________________________________________________________Multi-component copolymer 70 70 70 70 70 70 70 70*.sup.1 (NBR)rubber, partsComponent (A) composition (%)2-Cyanoethyl acrylate 56 35 25 36 864-Cyanobutyl acrylate 42Component (B) composition (%)Ethyl acrylate 31 53 30 56 97n-Butyl acrylate 41 31 12 31 11Component (C) composition (%)Ethylidenenorbornene 3 3 3 3 3Allyl glycidyl ether 3Vinyl chloroacetate 2Component (D) composition (%)Methoxyethyl acrylate 7PVC*.sup.2, parts 30 30 30 30 30 30 30 30Compound symbol*.sup.3 P Q P R S P P TProperties of crosslinkedrubberTensile strength, kg/cm.sup.2 204 197 202 223 216 153 117 191Elongation, % 420 370 450 410 400 620 170 510Hardness, JIS-A 71 70 69 72 68 67 82 70Gasoline resistance (After immersion of 40.degree. C. .times. 48 hr inFuel C).DELTA.V, % +18 +29 +30 +29 +35 +133 +7 +32Sour gasoline resistance (After immersion of 40 .degree. C. .times. 72 hr.times. n cycles inFuel C containing 2.5% of lauroyl peroxide)n=3 (3 cycles) NC*.sup.4 NC NC NC NC Softened NC Cracks appearedn=10 (10 cycles) NC NC NC NC NC Softened NC RupturedSour gasohol resistance (After immersion of 40.degree. .times. 72 hr.times. n cycles in asolution consisting of 80 volume % of Fuel C containing 2.5% of lauroylperoxide and20 volume % of methanol)n=3 (3 cycles) NC NC NC NC NC Softened NC Cracks appearedn=6 (6 cycles) NC NC NC NC NC Softened NC Rupturedn=10 (10 cycles) NC NC NC NC NC Softened NC RupturedHeat resistance (120 .degree. C. .times. 288 hr aging with air heating) Change of tensile +4 +6 +5 -3 -2 +12 -7 +5strength, %Change of elongation, % -27 -11 -20 -15 -17 -16 -32 -68Change of hardness, JIS-A +6 +8 +8 +6 +7 +4 +8 +27Ozone resistance, static (80 pphm, 40.degree. C., 100% elongation)24 hr NC NC NC NC NC NC C-3Ozone resistance, dynamic (80 pphm, 40.degree. C., 0 to 20% elongation)24 hr NC NC NC NC NC NC A-1288 hr NC NC NC NC NC NC RupturedLow-temperature resistance: -23 -19 -21 -25 -26 -14 -3 -22Gehman torsion test T100, .degree.C.__________________________________________________________________________ *.sup.1 JSR N 220S, manufactured by Japan Synthetic Rubber Co., Ltd. *.sup.2 Vinychlon 3000M, manufactured by Mitsui Toatsu Chemicals, Inc. *.sup.3 Refer to Table 10. *.sup.4 No cracking
TABLE 12__________________________________________________________________________ Comparative Example Example 48 49 50 51 52 32__________________________________________________________________________Multi-component copolymer rubber, parts 90 80 70 60 40 100PVC, parts 10 20 30 40 60 0Zinc oxide 5.0 5.0 5.0 5.0 5.0 5.0Stearic acid 1.0 1.0 1.0 1.0 1.0 1.0SRF carbon black 70.0 60.0 50.0 40.0 20.0 80.0DOP 5.0 5.0 5.0 5.0 5.0 5.0Accelerator TT 0.75 0.75 0.75 0.75 0.75 0.75Sulfur 0.2 0.2 0.2 0.2 0.2 0.2Properties of crosslinked rubberTensile strength, kg/cm.sup.2 189 201 217 220 195 126Elongation, % 460 460 430 410 370 480Hardness, JIS-A 68 70 71 72 74 69Sour gasoline resistance (After immersion of 40.degree. C. .times. 72 hr.times. n cycles in Fuel Ccontaining 2.5% of lauroyl peroxide)n=3 (3 cycles) NC NC NC NC NC NCn=10 (10 cycles) NC NC NC NC NC NCSour gasohol resistance (After immersion of 40.degree. C. .times. 72 hr.times. n cycles in a solutioncontaining of 80 volume % of Fuel C containing 2.5% oflauroyl peroxide and 20 volume % of methanol)n=3 (3 cycles) NC NC NC NC NC NCn=6 (6 cycles) NC NC NC NC NC Softenedn=10 (10 cycles) NC NC NC NC NC SoftenedPermanent compression set 37 41 43 46 57 28(120.degree. C. .times. 70 hr), %__________________________________________________________________________
EXAMPLES 53 TO 56 AND COMPARATIVE EXAMPLES 33 TO 36
Multi-component copolymer rubber compositions (Examples 53 to 56) and multi-component copolymer rubbers (Comparative Examples 33 to 36) were compounded by a Banbury mixer with the formulations shown in Table 13. The compounds obtained were evaluated for processability from dischargability from Banbury mixer as well as from knitting performance, and good processability was indicated so o, and bad processability as X.
These compounds were press-cured under the conditions shown in Table 13. The vulcanized compounds were subjected to measurement of permanent compression set, heat resistance and gasoline resistance based on JIS K 6301 using the conditions shown in Table 14.
The results are shown in Table 14.
Comparison between the results of Examples 53 and 54 with the results of Comparative Examples 33 and 34 indicates that mixing of a conventional acrylic rubber [a multi-component copolymer rubber (I)] with a multi-component copolymer rubber of this invention overcomes the drawbacks of the conventional acrylic rubber, namely, processability, permanent compression set and gasoline resistance.
Comparison between the results of Examples 55 and 56 with the results of Comparative Examples 35 and 36 indicates that the drawback of a multi-component copolymer rubber of this invention, namely, heat resistance is improved by incorporating thereinto a conventional acrylic rubber [a multi-component copolymer rubber (I)].
TABLE 13______________________________________ A B______________________________________Polymer 100 100Zinc oxide 5Stearic acid 1 1HAF carbon black 50 50Accelerator TT * 0.75Sulfur 0.2Ammonium benzoate 1Conditions for press-curing 170.degree. C. .times. 175.degree. C. .times. 20 min 20 min______________________________________ * tetramethylthiuram disulfide
TABLE 14__________________________________________________________________________ Example Comparative Example 53 54 55 56 33 34 35 36__________________________________________________________________________Multi-component (b) 10 (d) 20 (b) 80 (d) 70 (b) 100 (d) 100copolymer rubber ofthis inventionMulti-component (a) 90 (c) 80 (a) 20 (c) 30 (a) 100 (c) 100copolymer rubber (I)Compound formulation A B A B A B A BProcessability o o o o x x o oPermanent compression 62 61 59 57 82 75 56 49set, % (150.degree. C. .times. 70 hr)Heat resistance -32 -29 -41 -38 -29 -25 -52 -49(150.degree. C. .times. 70 hr)Change of elongation, %Gasoline resistance (After immersion of 40.degree. C. .times. 48 hr inFuel C).DELTA.V, % 85 79 45 56 115 123 31 30__________________________________________________________________________ (a) Ethyl acrylate/ethylidenenorbornene .times. 97/3 by weight (b) 2Cyanoethyl acrylate/nbutyl acrylate/ethylidenenorbornene .times. 49/48/3 by weight (c) Ethyl acrylate/butyl acrylate/methoxyethyl acrylate/allyl glycidyl ether .times. 40/30/27/3 by weight (d) 2Cyanoethyl acrylate/nbutyl acrylate/allyl glycidyl ether .times. 49/48/3 by weight
EXAMPLES 57 TO 61 AND COMPARATIVE EXAMPLES 37 TO 40
Each mixture having the formulation shown in Table 15 was kneaded by a Banbury mixer and an open roll and then press-cured at 170.degree. C. for 20 min.
Each crosslinked rubber composition was subjected to measurement of characteristics in accordance with JIS K 6301.
The rubber composition was also subjected to measurement of sour gasoline resistance by the following method:
[Test Method for Sour Gasoline Resistance]
A sample was immersed at 70.degree. C. for 24 hr in a solution obtained by dissolving 1 g of lauroyl peroxide in 99 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene). This 1 cycle procedure was repeated 20 times (20 cycles). Then, the sample was dried at 100.degree. C. for 15 hr under reduced pressure and subjected to measurement of tensile strength and elongation at break in accordance with JIS K 6301. The changes (%) from the value obtained before immersion were calculated and used as criteria of sour gasoline resistance.
The measurement results are shown in Table 16.
As is clear from Table 16, the composition of this invention gives a crosslinked product which is excellent in heat resistance, sour gasoline resistance, and ozone resistance, good in low-temperature resistance, tensile strength and elongation, and has a small permanent compression set.
TABLE 15______________________________________ Example Comparative Example 57 58 59 60 61 37 38 39 40______________________________________Copolymer (A.sub.1)*.sup.1 75 50 75 75 15 90Copolymer (A.sub.2)*.sup.2 75Copolymer (A.sub.3)*.sup.3 75Copolymer (A.sub.4)*.sup.4 75Copolymer (B.sub.1)*.sup.5 25 50 25 85 25 25Copolymer (B.sub.2)*.sup.6 25Copolymer (B.sub.3)*.sup.7 10Copolymer (B.sub.4)*.sup.8 25Zinc oxide .rarw. 5 .fwdarw.Stearic acid .rarw. 1 .fwdarw.HAF carbon black .rarw. 50 .fwdarw.Accelerator TT*.sup.9 .rarw. 0.75 .fwdarw.Sulfur .rarw. 0.2 .fwdarw.______________________________________ *.sup.1 A terpolymer produced by emulsion polymerization, consisting of 56% by weight of cyanoethyl acrylate, 41% by weight of butyl acrylate and 3% by weight of ethylidenenorbornene. Mooney viscosity ML.sub.1+4 (100.degree. C.) = 56 *.sup.2 A multicomponent copolymer produced by emulsion polymerization, consisting of 26% by weight of cyanoethyl acrylate, 12% by weight of buty acrylate, 53% by weight of ethyl acrylate, 3% by weight of ethylidenenorbornene and 6% by weight of methoxyethyl acrylate. Mooney viscosity ML.sub.1+4 (100.degree. C.) = 42 *.sup.3 A terpolymer produced by emulsion polymerization, consisting of 73% by weight of cyanoethyl acrylate, 24% by weight of butyl acrylate and 3% by weight of ethylidenenorbornene. Mooney viscosity ML.sub.1+4 (100.degree. C.) = 60 *.sup.4 A terpolymer produced by emulsion polymerization, consisting of 14% by weight of cyanoethyl acrylate, 83% by weight of butyl acrylate and 3% by weight of ethylidenenorbornene. Mooney viscosity ML.sub.1+4 (100.degree. C.) = 49 *.sup.5 A terpolymer produced by emulsion polymerization, consisting of 25% by weight of acrylonitrile, 40% by weight of butadiene and 35% by weight of butyl acrylate. Mooney viscosity ML.sub.1+4 (100.degree. C.) = 70 *.sup.6 A copolymer produced by emulsion polymerization, consisting of 35 by weight of acrylonitrile and 65% by weight of butadiene. Mooney viscosity ML.sub.1+4 (100.degree. C.) = 56 *.sup.7 A copolymer produced by emulsion polymerization, consisting of 35 by weight of acrylonitrile and 65% by weight of butadiene. A liquid rubbe whose [.eta.]as measured at 30.degree. C. in tetrahydrofuran is 0.05. *.sup.8 A terpolymer produced by emulsion polymerization, consisting of 30% by weight of acrylonitrile, 65% by weight of butadiene and 5% by weight of methacrylic acid. Mooney viscosity ML.sub.1+4 (100.degree. C.) 60 *.sup.9 Tetramethylthiuram disulfide
TABLE 16__________________________________________________________________________ Example Comparative Example 57 58 59 60 61 37 38 39 40__________________________________________________________________________Tensile strength, kg/cm.sup.2 145 151 162 131 162 175 105 112 124Elongation, % 360 370 420 430 370 380 480 220 450Hardness, JIS-A 72 70 72 69 71 69 68 78 68Gasoline resistance (After immersion of +35 +45 +31 +42 +33 +54 +21 +11 +5840.degree. C. .times. 48 hr in Fuel C) .DELTA.V, %Sour gasoline resistance (After immersionof 70.degree. C. .times. 24 hr .times. 20 cycles in Fuel Ccontaining 1% of lauroyl peroxide)Change of tensile strength, % -24 -41 -40 -44 -40 -72 -52 -18 -84Change of elongation, % -28 -45 -41 -38 -38 -83 -22 -25 -10Heat resistance (150.degree. C. .times. 12 hr agingwith air heating)Change of tensile strength, % +3 -2 +7 +2 +5 -65 -54 -21 +6Change of elongation, % -31 -41 -45 -49 -42 -92 -88 -64 -32Change of hardness, JIS-A +12 +17 +15 +15 +13 +21 +7 +18 +11Ozone resistance (50 pphm, 40.degree. C., .rarw. No cracking for 96 hr .fwdarw.30% elongation)Low-temperature resistance, Gehman -22 -25 -24 -23 -23 -26 -28 -7 -19torsion testT100, .degree.C.Permanent compression set, 150.degree. C. .times. 70 hr 25 32 31 59 38 61 29 53 33__________________________________________________________________________
EXAMPLES 62 TO 65 AND COMPARATIVE EXAMPLE 41
Test methods used in these Examples were as follows:
Preparation of Kneaded Compounds
Unvulcanized rubber compounds were kneaded by a rubber test roll mill (6-inch and 14-inch rolls) to obtain sheet-like kneaded compounds each having a thickness of 8 mm, a width of 50 mm and a length of 80 mm and having a smooth surface.
Adhesion by Vulcanization
A sheet-like kneaded compound of the multi-component copolymer rubber of this invention and another sheet-like kneaded compound of a different rubber both obtained above were superimposed and inserted into a compression type mold, where they were subjected to vulcanization at 170.degree. C. for 15 min at a surface pressure of 2 kg/cm.sup.2 applied by an electrically heated press whereby a sheet-like laminate was produced.
Measurement of Bonding Strength
The laminate obtained above was cut into a ribbon-like sample of 2.5 mm in width and the sample was subjected to 90.degree. peeling test in accordance with the peeling test specified by item 7 of JIS K 6801, whereby the bonding strength of the laminate was measured. The results are shown in Table 17.
Measurement of Sour Gasoline Resistance
A test specimen was immersed at 40.degree. C. for 72 hr in a solution obtained by dissolving 2.5 g of lauroyl peroxide in 97.5 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene), in such a way that the multi-component copolymer rubber of the laminate came in contact with the solution. This 1 cycle procedure was repeated twice (2 cycles). Then, the specimen was taken out of the solution, dried at 100.degree. C. for 15 hr under reduced pressure and bent at an angle of 180.degree. to observe the formation of cracks. The results are shown in Table 17.
The unvulcanized rubber compounds used in the above preparation of kneaded compounds had the following formulations, in which unless otherwise specified, parts are by weight:
______________________________________[Formulations of multi-component copolymer rubber compounds]Polymer (a) or (b) 100 partsSteatric acid 1HAF black 50Peroximon F40 0.2Ca(OH).sub.2 10 Note: (a) 2Cyanoethylacrylate/ethyl acrylate/nbutyl acrylate/ethylidenenorbornene = 37/30/30/3 by weight (b) 2Cyanoethyl acrylate/ethyl acrylate/2ethylhexyl acrylate/dicyclopentadiene = 25/40/32/3 by weight[Formulations of other rubber compounds]NBR: Polymer*.sup.1 100 parts Stearic acid 1 ZnO 5 SRF 50 Ca(OH).sub.2 10 Epoxy resin*.sup.2 5 Maleic anhydride 0.3 2-Methylimidazole 1.0 Sulfur 0.3 CZ 2 TET 1.5 TS 1FKM: Polymer*.sup.3 100 parts CMP #2*.sup.4 1.85 CMB #3*.sup.4 2.6 MgO 3 Ca(OH).sub.2 6 MT black 20 Note: *.sup.1 N 220S, manufactured by Japan Synthetic Rubber Co., Ltd. *.sup.2 Epicoat #828, manufactured by Shell *.sup.3 E45, manufactured by Du pont *.sup.4 Vulcanization accelerator, manufactured by Du Pont, #20 is a polycyclic quaternary phosphate and #30 is an aromatic salt.CZ: N--cyclohexylbenzothiazyl sulfenamideTET: Tetraethylthiuram disulfideTS: Tetramethylthiuram 25CR: Neoprene WRT*.sup.5 100 parts Stearic acid 0.5 SRF black 60 Hydrous silicic 20 acid Aromatic oil 15 ZnO 5 Accelerator 22 0.5______________________________________ Note: *.sup.5 A polychloroprene rubber, manufactured by Du Pont.
As seen from Examples 62 to 65, laminates between the multi-component copolymer rubber of this invention and a commercially available rubber have a strong bonding strength between the two rubbers as a result of vulcanization. (The two rubbers may be allowed to adhere to each other by the use of an adhesive).
Comparison of Example 62 with Comparative Example 41 indicates that a laminate of a multi-component copolymer rubber of this invention and an NBR has a strikingly improved sour gasoline resistance over the NBR.
TABLE 17__________________________________________________________________________ Example 62 63 64 65 Multi- Multi- Multi- Multi- component component component component Comparative copolymer copolymer copolymer copolymer Example rubber rubber rubber rubber 41 (a)/NBR (a)/FKM (a)/CR (b)/NBR NBR__________________________________________________________________________Bonding strength 2.1 2.0 2.5 2.3 --(peeling strengthof laminate),kg/cm.sup.2Sour gasoline NC*.sup.2 NC*.sup.2 NC*.sup.2 NC*.sup.2 Cracksresistance *.sup.1 appeared.__________________________________________________________________________ *.sup.1 After immersion of 40.degree. C. .times. 72 hr .times. 2 cycles i Fuel C containing 2.5% of lauroyl peroxide. *.sup.2 No cracking
EXAMPLES 66 TO 72 AND COMPARATIVE EXAMPLE 42
Each sample of multi-component copolymer rubbers (Examples 66 to 72) and a butadiene-acrylonitrile rubber (NBR) (Comparative Example 42) shown in the upper section of Table 19 was subjected to compounding by a Banbury mixer in accordance with the formulation shown in Table 18. Each compound obtained was press-cured under the conditions shown in the bottom section of Table 18.
The crosslinked rubber compounds obtained were subjected to measurement of characteristics in accordance with JIS K 6301. The results are shown in Table 19.
The crosslinked rubber compounds were also subjected to measurement of sour gasoline resistance by the following method. The results are shown in Table 19.
[Text Method for Sour Gasoline Resistance]
A test specimen was immersed at 40.degree. C. for 72 hr in a solution obtained by dissolving 2.5 g of lauroyl peroxide in 97.5 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene). This 1 cycle procedure was repeated n times (n cycles). After each cycle, the specimen was taken out, dried at 100.degree. C. for 15 hr under reduced pressure and bent at an angle of 180.degree. to observe the formation of cracks.
As appreciated from Table 19, the rubber compounds of this invention are excellent in sour gasoline resistance, heat resistance and ozone resistance and good in permanent compression set and balance between gasoline resistance and low-temperature resistance. Therefore, they provide a very superior material for inner tubes of fuel rubber hoses.
TABLE 18__________________________________________________________________________ Compound symbol A B C D E__________________________________________________________________________Compound formulationPolymer 100.0 100.0 100.0 100.0 100.0Zinc oxide 5.0 5.0Stearic acid 1.0 1.0 1.0 1.0 1.0HAF carbon black*.sup.0 50.0 50.0 50.0 50.0DOP*.sup.2 5.0Accelerator TT*.sup.3 0.75 1.5Accelerator CZ*.sup.4 2.0Accelerator TRA*.sup.5 0.5Accelerator EUR*.sup.6 1.0Sulfur 0.2 0.5Peroximon F40*.sup.7 2.0Ammonium benzoate 1.0Potassium stearate 3.0SRF carbon black*.sup.1 60.0Conditions for press-curing 170.degree. C. .times. 180.degree. C. .times. 175.degree. C. .times. 175.degree. C. .times. 160.degree. C. .times. 20 min 20 min 20 min 20 min 20 min__________________________________________________________________________ *.sup.0 High abrasion furnace black *.sup.1 Semi-reinforcing furnace black *.sup.2 Dioctyl phthalate *.sup.3 Tetramethylthiuram disulfide *.sup.4 N-- cyclohexyl-2-benzothiazolesulfenamide *.sup.5 Dipentamethylenethiuram hexasulfide *.sup.6 1,3-Diethylthiourea *.sup.7 1,3-Bis(t-butylperoxyisopropyl)benzene
TABLE 19__________________________________________________________________________ Comparative Example Example 66 67 68 69 70 71 72 42__________________________________________________________________________Multi-component copolymerrubber composition,Component (A)2-Cyanoethyl acrylate 49 37 26 35 83 12 NBR*.sup.14-Cyanobutyl acrylate 44Component (B)Ethyl acrylate 30 52 31 54n-Butyl acrylate 48 30 14 31 14 85Component (C)Ethylidene norbornene 3 3 3 3 3Allyl glycidyl ether 3Vinyl chloroacetate 2Component (D)Methoxyethyl acrylate 5Compound symbol*.sup.2 A B A C D A A AProperties of crosslinkedrubberTensile strength, kg/cm.sup.2 131 136 129 154 142 83 132 197Elongation, % 480 410 500 380 530 160 520 490Hardness, JIS-A 72 71 69 67 65 84 66 72Gasoline resistance (After immersion of 40.degree. C. .times. 48 hr inFuel C).DELTA.V, % +31 +35 +38 +39 +41 +4 +70 +40Sour gasoline resistance (After immersion of 40.degree. C. .times. 72 hr.times. n cycles inFuel C containing 2.5% of lauroyl peroxide)n=2 (2 cycles) NC*.sup.3 NC NC NC NC NC NC Cracks appearedn=4 (4 cycles) NC NC NC NC NC NC Softened Rupturedn=8 (8 cycles) NC NC NC NC NC NC Softened RupturedHeat resistance (150.degree. C. .times. 72 hr aging with air heating)Change of tensile -8 .+-.0 -11 +4 -9 -11 +2 -82Strength, %Change of elongation, % -51 -26 -38 -32 -37 -57 -29 -100 (No elonga- tion)Change of hardness, JIS-A +13 +9 +12 +13 +14 +14 +10 +25Ozone resistance (50 pphm, 40.degree. C., .rarw. No cracking for 168 hr .fwdarw. Cracks30% elongation) appeared in 2 hr.Low-temperature resistance: -24 -21 -21 -25 -28 -2 -13 -21Gehman torsion test T100, .degree.C.Permanent compression set, 51 23 56 47 54 63 61 66(150.degree. C. .times. 70 hr), %__________________________________________________________________________ *.sup.1 JSR N220S, manufactured by Japan Synthetic Rubber Co., Ltd. *.sup.2 Refer to Table 18. *.sup.3 No cracking

Number	Date	Country
59-60351	Mar 1984	JPX
59-60352	Mar 1984	JPX
59-60353	Mar 1984	JPX
59-61757	Mar 1984	JPX
59-61758	Mar 1984	JPX
59-64132	Mar 1984	JPX
59-64133	Mar 1984	JPX
59-68678	Apr 1984	JPX
59-75583	Apr 1984	JPX
59-167544	Aug 1984	JPX
59-244127	Nov 1984	JPX

Number	Name	Date
3397193	Aloia	Aug 1968
3445403	Tucker	May 1969
4490515	Mariotti	Dec 1984

Multi-component copolymer rubber, a process for producing the same and a rubber composition containing the multi-component copolymer rubber

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