RTV organopolysiloxane compositions

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to room temperature vulcanizable organopolysiloxane compositions which are readily vulcanizable with moisture in the air to form rubbery elastomers having improved water immersion and thermoresistant adhesion.
2. Prior Art
Room temperature vulcanizable (RTV) organopolysiloxane compositions which readily cure with moisture to form rubbery elastomers are well-known in the art. They are widely used in a variety of fields as adhesives, coatings, electrically insulating sealants, and building sealants because the cured elastomers have excellent characteristics including weather resistance, durability and freeze resistance.
Recently, acryl resin and fluoro-resin electrodeposited aluminum members featuring weather resistance and having a less adhesive surface have been utilized as building exterior materials. RTV organopolysiloxane compositions do not firmly bond to such aluminum members surface coated with acryl resins and fluoro-resins. The organopolysiloxane compositions applied to the surface coated aluminum members also suffer from the problem that they become peeled when immersed in water for a long time.
Known RTV organopolysiloxane compositions are often loaded with calcium carbonate as a filler. For example, JP-A 39422/1993 discloses the use of calcium carbonate which has been treated with 3% by weight of a treating agent in the form of rhodinic acid. The use of calcium carbonate as a filler is also proposed in JP-A 179760/1995 and U.S. Pat. No. 5,405,889 (issued Apr. 11, 1995). Allegedly these compositions are also improved in anti-spitting and adhesion. These compositions, however, are not satisfactory in water immersion and thermoresistant adhesion to less adhesive surface coatings on aluminum members and mortar.
It was proposed by Dow Corning Toray Silicone Co. to use a filler blend of calcium carbonate treated with stearic acid and fumed silica. In water immersion and heating tests, however, the stearic acid on the surface of calcium carbonate leaches out to adversely affect the adhesion. This proposal is thus not satisfactory in performance.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a novel and improved RTV organopolysiloxane composition which cures into a product firmly bondable to surface treated aluminum members and maintaining improved water immersion and thermoresistant adhesion.
According to the present invention, there is provided a room temperature vulcanizable (RTV) organopolysiloxane composition comprising (1) a diorganopolysiloxane of the following general formula (I): ##STR1## wherein R.sup.1 is a substituted or unsubstituted monovalent hydrocarbon group and n is a positive integer, (2) an organic silicon compound having at least three hydrolyzable groups in a molecule, and (3) calcium carbonate which has been treated with up to 2.5% by weight based on the calcium carbonate of an agent having a melting or softening point of at least 100.degree. C. or a saturated fatty acid represented by C.sub.m H.sub.2m+1 COOH wherein m is an integer of at least 20. The composition may optionally contain (4) a fumed silica filler.
When calcium carbonate which has been treated with up to 2.5% by weight, preferably 1 to 2.5% by weight of an agent having a melting or softening point of at least 100.degree. C. or a saturated fatty acid as defined above is blended in an RTV organopolysiloxane composition comprising a diorganopolysiloxane of formula (I) and an organic silicon compound having at least three hydrolyzable groups, the resulting composition will cure into a product which well adheres to adherends, especially aluminum members surface treated with fluoro-resins and acryl resins, for example. The cured product maintains adhesion to such adherends upon water immersion and at elevated temperatures. Further blending of fumed silica filler improves the adhesion of the composition to mortar. In this way, the invention overcomes the problems of the prior art.
DETAILED DESCRIPTION OF THE INVENTION
The RTV organopolysiloxane composition of the present invention uses as a base polymer a diorganopolysiloxane of the following general formula (I): ##STR2## wherein R.sup.1 is a substituted or unsubstituted monovalent hydrocarbon group and letter n is a positive integer.
In formula (I), R.sup.1 is a substituted or unsubstituted monovalent hydrocarbon group, preferably selected from those of 1 to 10 carbon atoms, more preferably those of 1 to 8 carbon atoms, for example, alkyl groups such as methyl, ethyl, propyl, butyl and hexyl, aryl groups such as phenyl and tolyl, alkenyl groups such as vinyl, allyl, butenyl, and hexenyl, cycloalkyl groups such as cyclohexyl, aralkyl groups such as benzyl and 2-phenylethyl, and substituted ones of these groups wherein some or all of the hydrogen atoms attached to carbon atoms are replaced by halogen atoms or cyano groups, such as chloromethyl, trifluoropropyl and cyanoethyl. Especially preferred are methyl, phenyl, vinyl, and trifluoropropyl groups.
Letter n, which is a positive integral number corresponding to a degree of polymerization, is preferably a positive integer of 50 to 2,000, especially 100 to 2,000 when viscosity and workability are taken into account. Preferably the value of n is adjusted such that the diorganopolysiloxane of formula (I) may have a viscosity of 50 to 1,000,000 centistokes at 25.degree. C., especially 700 to 100,000 centistokes at 25.degree. C.
Illustrative examples of the diorganopolysiloxane of formula (I) are given below. ##STR3## In the formulae, Me is methyl, Ph is phenyl, p and q are positive integers, p+q is an integer corresponding to n.
The second component is an organic silicon compound having at least three hydrolyzable groups in a molecule. It serves as a curing agent and is essential for the inventive composition to cure at room temperature in the presence of moisture. The organic silicon compound may be selected from well-known curing agents for conventional RTV condensation type organopolysiloxane compositions.
Examples of the hydrolyzable group in the organic silicon compound include alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, and methoxyethoxy; alkenyloxy groups such as propenoxy, isobutenyloxy, and 1-ethyl-2-methylvinyloxy; ketoxime groups such as dimethylketoxime, methylethylketoxime, diethylketoxime, cyclopentanoxime, and cyclohexanoxime; acyloxy groups such as acetoxy, propionoxy, butyroyloxy, and benzoyl; amino groups such as N-methylamino, N-ethylamino, N-propylamino, N-butylamino, N,N-dimethylamino, N,N-diethylamino, and cyclohexylamino; amide groups such as N-methylacetamide and N-methylbenzamide; aminoxy groups such as N,N-dimethylaminoxy and N,N-diethylaminoxy; isocyanato group; .alpha.-silylester groups; and halogen atoms such as chloro. Especially preferred are methoxy, dimethylketoxime, diethylketoxime, and methylethylketoxime groups.
In addition to the hydrolyzable groups, the organic silicon compound may have another group attachable to a silicon atom, for example, a substituted or unsubstituted monovalent hydrocarbon group as defined for R.sup.1 in the first component. Alkyl groups having 1 to 8 carbon atoms, alkenyl groups having 2 to 10 carbon atoms and phenyl groups are preferred because of ease of synthesis.
Illustrative, non-limiting examples of the organic silicon compound as the second component include alkoxysilanes such as methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and 3-chloropropyltrimethoxysilane; enoxysilanes such as methyltriisopropenoxysilane, vinyltriisopropenoxysilane, and phenyltriisopropenoxysilane; ketoximesilanes such as methyltris(methylethylketoxime)silane, vinyltris(methylethylketoxime)silane, phenyltris(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, and tetrakis(methylethylketoxime)silane; aminosilanes such as methyltriacetoxysilane, vinyltriaacetoxysilane, and phenyltris(N,N-diethylamino)silane; aminoxysilanes such as methyltris(N-methylacetamido)silane, vinyltris(N-aminoxy)silane, and vinyltris(N,N-diethylaminoxy)silane; and partial hydrolyzates of these compounds.
Preferably the organic silicon compound as the second component is blended in an amount of 0.2 to 30 parts, especially 0.5 to 20 parts by weight per 100 parts by weight of the diorganopolysiloxane of formula (I) as the first component. Less than 0.2 part of the organic silicon compound would cause undercuring of the composition. More than 30 parts of the organic silicon compound would cause the composition to cure into a hard and brittle product losing sealant capabilities.
According to the invention, there is blended as a third component calcium carbonate which has been treated with a treating agent. The treating agent is one having a melting or softening point of at least 100.degree. C. or a saturated fatty acid represented by C.sub.m H.sub.2m+1 COOH wherein m is an integer of at least 20. Calcium carbonate is treated with up to 2.5% by weight of the treating agent based on the weight of calcium carbonate.
It is essential that calcium carbonate as the third component has been treated with a treating agent having a melting or softening point of at least 100.degree. C. or a saturated fatty acid represented by C.sub.m H.sub.2m+1 COOH wherein m is as defined above. More adhesion and durability are accomplished when the following requirements are met.
(A) Calcium carbonate having a mean particle size of up to 0.2 .mu.m is used.
(B) The amount of the treating agent ranges from 1 to 2.5% by weight based on the weight of calcium carbonate.
The calcium carbonate used herein is preferably a particulate one having a mean particle size of up to 0.2 .mu.m, more preferably 0.01 to 0.2 .mu.m, most preferably 0.01 to 0.1 .mu.m. With a mean particle size of more than 0.2 .mu.m, the resulting silicone rubber would have insufficient mechanical strength.
In one embodiment, calcium carbonate is treated with a treating agent having a melting or softening point of at least 100.degree. C., preferably 150.degree. to 400.degree. C. Calcium carbonate having been treated with a treating agent having a melting or softening point of less than 100.degree. C. fails to form a bond which is resistant to heat and tolerant against warm water immersion. Saturated fatty acids represented by C.sub.m H.sub.2m+1 COOH wherein m is an integer of at least 20 are also useful as a treating agent even if their melting or softening point is less than 100.degree. C. The objects of the invention are not accomplished by saturated fatty acids represented by C.sub.m H.sub.2m+1 COOH wherein m is an integer of less than 20.
The treating agent with which the calcium carbonate is treated is preferably selected from those water-immiscible agents having a melting or softening point of at least 1000.degree. C., including rhodinic acid, silicone resins, and saturated fatty acids represented by C.sub.m H.sub.2m+1 COOH wherein m is an integer of at least 20, especially at least 35.
The amount of the treating agent used is up to 2.5%, preferably 1 to 2.5%, more preferably 1.5 to 2.5% by weight based on the weight of calcium carbonate to be treated therewith. If the amount of the treating agent used is outside this range, the composition fails to form a bond which is resistant to heat and tolerant against warm water immersion. Treatment of calcium carbonate may be done by conventional techniques.
Preferably the treated calcium carbonate as the third component is blended in an amount of 10 to 100 parts, especially 25 to 90 parts by weight per 100 parts by weight of the diorganopolysiloxane as the first component. Compositions with less than 10 parts of the treated calcium carbonate would flow too much and become rather difficult to work whereas compositions with more than 100 parts of the treated calcium carbonate would become too hard and also difficult to work.
In one preferred embodiment, a fumed silica filler is blended in the composition as a fourth component. Then the composition is further improved in adhesion to not only surface treated aluminum members, but also mortar. As compared with compositions filled solely with calcium carbonate, compositions filled with both calcium carbonate and fumed silica will effectively fill in interstices to prevent water penetration, achieving better adhesion under water immersion. In cured products, the calcium carbonate and fumed silica filled together cooperate to effectively absorb external forces so that little force is applied to the interface with the adherend or support and interfacial separation scarcely occurs.
The fumed silica used herein may be either surface treated or not. Fumed silicas surface treated with hexamethyldisilazane, chlorosilane and alkoxysilanes are preferred from the standpoints of shelf stability and physical properties. It is also preferred to use fumed silica having a specific surface area of at least 50 m.sup.2 /g, especially 100 to 400 m.sup.2 /g.
Preferably the fumed silica as the fourth component is blended in an amount of 0.1 to 30 parts, especially 1 to 10 parts by weight per 100 parts by weight of the first and third components combined when workability and rubber physical properties are taken into account. Compositions with more than 30 parts of fumed silica would become too hard adversely affecting workability and physical properties. Less than 0.1 part of fumed silica would not alter physical properties.
For promoting curing of RTV organopolysiloxane compositions, a condensation catalyst is preferably used. The condensation catalyst used herein may be selected from known condensation catalysts commonly used in similar compositions as a curing promoter, for example, organic tin compounds such as dibutyltin methoxide, dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, dimethyltin dimethoxide, and dimethyltin diacetate; organic titanium compounds such as tetrapropyl titanate, tetrabutyl titanate, tetra-2-ethylhexyl titanate, and dimethoxytitanium diacetylacetonate; amine compounds such as hexylamine, 3-aminopropyltrimethoxysilane, and tetramethylguanidylpropyltrimethoxysilane; and salts thereof alone or in admixture of two or more.
Preferably the condensation catalyst is used in an amount of up to 10 parts, especially 0 to 5 parts by weight per 100 parts by weight of the diorganopolysiloxane as the first component. More than 10 parts of the condensation catalyst would cause undercuring, detracting from sealing capability.
In addition to the condensation catalyst, the composition of the invention may further have blended therein various additives such as fillers, pigments, dyes, tackifiers, thixotropic agents, rust-preventing agents, flame retardants, and antiseptic agents. These optional components may be blended in conventional amounts insofar as the objects of the invention are not impaired.
The RTV organopolysiloxane composition of the invention is well bondable to adherends, especially surface treated aluminum members and cures into a product which maintains a firm bond under water immersion and at elevated temperatures. The composition will thus find use as adhesives, coatings, electrically insulating sealants, and building sealants.

EXAMPLE
Examples are given below by way of illustration and not by way of limitation. All parts are by weight. The viscosity is as measured at 25.degree. C.
Example 1
An RTV organopolysiloxane composition was obtained by charging a universal mixer with 60 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 50,000 centistokes, 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 2.0% by weight of rhodinic acid (melting point 162.degree. C.), 6 parts of (methylethylketoxime)silane, 0.02 part of polypropylene glycol, 0.1 part of dibutyltin dimethoxide, and 1 part of .gamma.-aminopropyltriethoxysilane, followed by debubbling and mixing.
Example 2
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 2.0% by weight of C.sub.35 H.sub.71 COOH (melting point 101.degree. C.) was used instead of the 2.0% rhodinic acid-treated calcium carbonate.
Example 3
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 2.0% by weight of a phenylsilicone resin (softening point 150.degree. C.) was used instead of the 2.0% rhodinic acid-treated calcium carbonate.
Example 4
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 2.0% by weight of a dimethylsilicone resin (softening point 110.degree. C.) was used instead of the 2.0% rhodinic acid-treated calcium carbonate.
Example 5
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 40 parts of calcium carbonate with a particle size of 0.15 .mu.m and treated with 2.0% by weight of rhodinic acid was used.
Example 6
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 25 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 20,000 centistokes and 35 parts of .alpha.,.omega.)-dihydroxydimethylpolysiloxane having a viscosity of 100,000 centistokes were used as the dimethylpolysiloxane and 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of rhodinic acid was used.
Example 7
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 7 parts of methyltrimethoxysilane was used instead of 6 parts of (methylethylketoxime)silane.
Comparative Example 1
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 2.0% by weight of liquid oleic acid was used instead of the 2.0% rhodinic acid-treated calcium carbonate and 0.1 part of dimethyltin dimethoxide was used instead of the dibutyltin dimethoxide.
Comparative Example 2
An RTV organopolysiloxane composition was obtained by the same procedure as in Comparative Example 1 except that 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 2.0% by weight of stearic acid (melting point 72.degree. C.) was used instead of the 2.0% oleic acid-treated calcium carbonate.
Comparative Example 3
An RTV organopolysiloxane composition was obtained by the same procedure as in Comparative Example 1 except that 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 2.0% by weight of a dimethylsilicone resin (softening point 40.degree. C.) was used instead of the 2.0% oleic acid-treated calcium carbonate.
Comparative Example 4
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 1 except that 40 parts of calcium carbonate with a particle size of 0.08 .mu.m and treated with 3.0% by weight of rhodinic acid was used instead of the 2.0% rhodinic acid-treated calcium carbonate.
The RTV organopolysiloxane compositions obtained in Examples 1-7 and Comparative Examples 1-4 were subject to a block H-1 type adhesion test according to JIS A 5758. The results are shown in Tables 1 and 2.
Block H-1 type adhesion test
Adherends:
A: float glass
B: fluoro-resin electrodeposited aluminum plate
C: Kainer fluoro-resin coated aluminum plate
D: glossy acryl resin electrodeposited aluminum plate
E: matte acryl resin electrodeposited aluminum plate
Measurement:
Each of the RTV organopolysiloxane compositions was applied to an adherend and cured at a temperature of 20.degree. C. and a humidity of 55% for 7 days. The resulting integral block was removed from the mold and aged for 7 days under the same conditions before it was measured for initial properties. In a water immersion test, the sample block as prepared above was immersed in water at 50.degree. C. for 21 days before it was measured for properties again. In a heat resistance test, the sample block as prepared above was kept in a dryer at 1000.degree. C. for 21 days before it was measured for properties again. The tensile tester used for the measurement of the sample block was Strograph R-2 manufactured by Toyo Seiki Mfg. K.K. which was operated at a pulling rate of 50 mm/min.
It is noted that Tmax is maximum tensile strength, Emax is maximum elongation, and CF is a percent retention of the sealant when the fractured surfaces of the adherend and the sealant after the tensile test were visually observed. Under the heading "Adherend," A to E stand for the above-mentioned adherends.
TABLE 1__________________________________________________________________________ Curing conditions 20.degree. C. .times. 55% .times. 14 days 20.degree. C. .times. 55% .times. 14 20.degree. C. .times. 55% .times. 14 days Test Conditions 50.degree. C./21 days heating Initial in water 100.degree. C./21 days Tmax Emax CF Tmax Emax CF Tmax Emax CFExample Adherend (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%)__________________________________________________________________________1 A 13.1 284 100 7.7 362 100 8.6 343 100 B 10.7 284 100 7.5 316 100 8.3 323 100 C 10.6 266 100 7.5 340 100 8.6 350 100 D 11.2 318 100 7.4 329 100 8.4 311 100 E 10.5 301 100 7.4 310 100 8.2 309 1002 A 12.3 267 100 8.1 301 100 9.2 297 100 B 11.0 288 100 8.4 311 100 9.4 288 100 C 10.9 299 100 8.5 322 100 9.5 276 100 D 13.7 256 100 7.8 306 100 9.2 267 100 E 11.7 259 100 7.5 299 100 8.9 279 1003 A 9.7 213 100 8.2 255 100 7.9 220 100 B 9.2 209 100 7.9 254 100 7.2 235 95 C 9.3 204 100 8.1 245 100 7.3 218 100 D 8.9 220 100 8.3 238 100 7.2 208 100 E 8.8 197 100 8.2 244 100 7.3 207 1004 A 7.4 199 100 5.7 240 100 6.8 211 100 B 6.7 176 100 5.2 182 80 6.4 202 90 C 6.9 179 100 4.9 212 90 6.7 203 100 D 7.8 188 100 5.6 209 100 6.3 211 100 E 7.2 170 100 5.1 234 90 6.1 221 1005 A 8.8 245 100 4.8 299 100 7.8 252 100 B 8.8 242 100 4.7 297 95 7.4 253 100 C 7.9 211 100 4.6 291 100 7.5 249 100 D 9.1 230 100 4.7 295 100 7.3 239 100 E 8.7 223 100 4.5 288 90 7.9 243 1006 A 9.9 295 100 7.0 270 100 8.3 263 100 B 10.3 279 100 7.1 273 100 7.5 260 100 C 7.9 200 100 7.3 297 100 8.1 255 100 D 10.3 290 100 7.0 272 100 7.9 261 100 E 9.5 289 100 7.2 264 100 7.5 256 1007 A 6.5 189 100 6.0 211 100 5.2 172 100 B 6.6 167 100 6.2 221 100 5.8 167 100 C 5.4 190 100 6.4 224 100 5.9 168 100 D 6.8 158 100 6.1 189 100 5.1 179 100 E 5.3 188 100 6.4 199 100 5.9 158 100__________________________________________________________________________
TABLE 2__________________________________________________________________________ Curing conditions 20.degree. C. .times. 55% .times. 14 days 20.degree. C. .times. 55% .times. 14 20.degree. C. .times. 55% .times. 14 days Test Conditions 50.degree. C./21 days heatingCompara- Initial in water 100.degree. C./21 daystive Tmax Emax CF Tmax Emax CF Tmax Emax CFExample Adherend (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%)__________________________________________________________________________1 A 10.7 313 100 8.8 323 90 5.1 403 70 B 10.8 300 0 7.2 390 0 3.7 223 0 C 8.9 236 80 6.7 403 50 4.9 250 10 D 9.7 328 100 7.4 356 100 5.0 210 50 E 9.5 222 40 5.2 310 0 2.8 109 02 A 10.2 369 95 7.8 358 80 9.7 341 90 B 7.4 174 0 7.0 171 0 7.4 162 0 C 4.9 299 50 4.7 267 0 4.2 276 0 D 11.4 368 8O 6.9 389 50 5.2 233 30 E 4.1 172 0 2.8 99 0 3.8 88 03 A 6.8 233 100 4.1 205 0 s.9 210 80 B 4.1 219 80 3.2 173 0 4.1 215 0 C 5.3 214 80 3.8 195 0 4.3 201 50 D 4.3 212 100 4.0 183 0 4.2 198 60 E 4.6 187 70 2.2 104 0 4.3 109 04 A 10.5 380 90 8.0 387 70 8.9 355 90 B 8.7 332 90 8.3 356 50 8.4 362 0 C 10.4 311 90 8.1 356 70 8.1 333 80 D 10.6 324 90 8.5 389 90 8.9 311 90 E 10.2 302 80 5.1 234 0 4.0 221 0__________________________________________________________________________
As is evident from Tables 1 and 2, RTV organopolysiloxane compositions within the scope of the invention (Examples 1-7) provide a firm bond to surface treated aluminum plates and maintain such bond under water immersion and at elevated temperature.
Example 8
An RTV organopolysiloxane composition was obtained by charging a universal mixer with 60 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 50,000 centistokes, 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of rhodinic acid (melting point 162.degree. C.), 6 parts of (methylethylketoxime)silane, 0.02 part of polypropylene glycol, 0.1 part of dibutyltin dimethoxide, 3 parts of surface treated fumed silica (trade name R-972 by Nippon Aerosil K.K.), and 1 part of .gamma.-aminopropyltriethoxysilane, followed by debubbling and mixing.
Example 9
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 8 except that 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of C.sub.21 H.sub.43 COOH (melting point 82.degree. C.) was used instead of the 2.0% rhodinic acid-treated calcium carbonate.
Example 10
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 8 except that 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of a phenylsilicone resin (softening point 150.degree. C.) was used instead of the 2.0% rhodinic acid-treated calcium carbonate.
Example 11
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 8 except that 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of a dimethylsilicone resin (softening point 110.degree. C.) was used instead of the 2.0% rhodinic acid-treated calcium carbonate.
Example 12
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 8 except that 40 parts of calcium carbonate with a particle size of 0.15 .mu.m and treated with 2.0% by weight of rhodinic acid was used.
Example 13
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 8 except that 25 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 20,000 centistokes and 35 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 100,000 centistokes were used as the dimethylpolysiloxane and 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of rhodinic acid was used.
Example 14
An RTV organopolysiloxane composition was obtained by the same procedure as in Example 8 except that 7 parts of methyltrimethoxysilane was used instead of 6 parts of (methylethylketoxime)silane.
Example 15
An RTV organopolysiloxane composition was obtained by charging a universal mixer with 70 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 50,000 centistokes, 30 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 1.5% by weight of rhodinic acid (melting point 162.degree. C.), 6 parts of (methylethylketoxime)silane, 0.02 part of polypropylene glycol, 0.1 part of dibutyltin dimethoxide, 3 parts of fumed silica (trade name Aerosil 200 by Nippon Aerosil K.K.), and 1 part of .gamma.-aminopropyltriethoxysilane, followed by debubbling and mixing.
Example 16
An RTV organopolysiloxane composition was obtained by charging a universal mixer with 80 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 50,000 centistokes, 20 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 1.5% by weight of rhodinic acid (melting point 1620.degree. C.), 6 parts of (methylethylketoxime)silane, 0.02 part of polypropylene glycol, 0.1 part of dibutyltin dimethoxide, 6 parts of surface treated fumed silica (R-972), and 1 part of .gamma.-aminopropyltriethoxysilane, followed by debubbling and mixing.
Comparative Example 5
An RTV organopolysiloxane composition was obtained by charging a universal mixer with 60 parts of .alpha.,.omega.-dihydroxydimethylpolysiloxane having a viscosity of 50,000 centistokes, 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of stearic acid, 6 parts of (methylethylketoxime)silane, 0.02 part of polypropylene glycol, 0.1 part of dimethyltin dimethoxide, 3 parts of surface treated fumed silica (R-972), and 1 part of .gamma.-aminopropyltriethoxysilane, followed by debubbling and mixing.
Comparative Example 6
An RTV organopolysiloxane composition was obtained by the same procedure as in Comparative Example 5 except that 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 2.0% by weight of a dimethylsilicone resin (softening point 40.degree. C.) was used instead of the 2.0% stearic acid-treated calcium carbonate.
Comparative Example 7
An RTV organopolysiloxane composition was obtained by the same procedure as in Comparative Example 5 except that 40 parts of calcium carbonate with a particle size of 0.06 .mu.m and treated with 3.0% by weight of rhodinic acid (melting point 162.degree. C.) was used instead of the 2.0% stearic acid-treated calcium carbonate.
Comparative Example 8
An RTV organopolysiloxane composition was obtained by the same procedure as in Comparative Example 5 except that 40 parts of untreated colloidal calcium carbonate with a particle size of 0.06 .mu.m was used instead of the 2.0% stearic acid-treated calcium carbonate.
The RTV organopolysiloxane compositions obtained in Examples 8-16 and Comparative Examples 5-8 were subject to a block H-1 type adhesion test according to JIS A 5758. The test procedure was the same as above except that mortar was used as an additional adherend. The results are shown in Tables 3 and 4. Under the heading of "Adherend" in these Tables, F stands for mortar while A to E are as defined previously.
TABLE 3__________________________________________________________________________ Curing conditions 20.degree. C. .times. 55% .times. 14 days 20.degree. C. .times. 55% .times. 14 20.degree. C. .times. 55% .times. 14 days Test Conditions 50.degree. C./21 days heating Initial in water 100.degree. C./21 days Tmax Emax CF Tmax Emax CF Tmax Emax CFExample Adherend (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%)__________________________________________________________________________8 A 12.8 384 100 9.7 362 100 8.6 333 100 B 11.7 384 100 9.5 416 100 8.3 323 100 C 11.6 366 100 9.5 440 100 8.6 350 100 D 11.2 418 100 9.4 429 100 8.4 311 100 E 11.5 401 100 9.4 410 100 8.2 309 100 F 10.9 355 100 8.7 322 100 8.1 296 1009 A 13.3 276 100 9.1 310 100 10.8 288 100 B 12.0 288 100 9.4 311 100 10.4 253 100 C 11.9 299 100 9.5 333 100 10.7 299 100 D 12.7 266 100 9.8 368 100 10.2 288 100 E 12.7 295 100 9.5 301 100 10.9 292 100 F 11.3 300 100 9.2 311 100 9.9 279 10010 A 7.7 231 100 7.2 225 100 7.9 230 100 B 7.2 219 100 7.9 234 100 7.2 235 90 C 7.3 224 100 7.1 235 100 7.3 238 100 D 7.9 202 100 7.3 238 100 7.2 240 100 E 7.8 188 100 7.2 236 100 7.3 207 100 F 7.1 203 100 7.5 235 100 7.4 211 10011 A 6.4 299 100 5.2 204 100 5.8 211 100 B 5.7 267 100 5.0 185 80 5.4 212 90 C 6.9 279 100 5.9 192 90 5.7 223 100 D 5.8 288 100 5.6 189 100 5.3 211 100 E 6.2 271 100 5.1 214 90 5.1 212 100 F 7.1 210 100 5.7 187 80 5.1 189 8012 A 9.8 345 100 6.5 399 100 6.8 352 100 B 9.8 324 100 6.9 397 95 6.4 335 100 C 9.9 315 100 6.6 391 100 6.5 393 100 D 10.1 305 100 6.7 395 100 6.3 339 100 E 9.7 323 100 6.5 388 90 6.9 344 100 F 9.3 299 100 6.2 378 95 6.1 379 10013 A 9.9 295 100 7.0 270 100 8.3 263 100 B 10.3 279 100 7.1 273 100 7.5 260 100 C 7.9 200 100 7.3 297 100 8.1 255 100 D 10.3 290 100 7.0 272 100 7.9 261 100 E 9.5 289 100 7.2 264 100 7.5 256 100 F 8.6 277 100 6.8 258 100 6.9 249 10014 A 6.5 169 100 6.0 211 100 5.2 172 100 B 6.6 167 100 6.2 221 100 5.8 167 100 C 5.4 190 100 6.4 224 100 5.9 168 100 D 6.8 15B 100 6.1 189 100 5.1 179 100 E 5.3 188 100 6.4 199 100 5.9 158 100 F 5.2 169 100 4.9 188 100 4.9 152 10015 A 8.4 321 100 6.8 332 100 7.3 299 100 B 7.5 305 100 6.2 323 100 7.8 2B7 100 C 8.1 298 100 6.9 315 100 7.4 282 100 D 7.6 301 100 6.1 341 100 7.5 279 100 E 7.2 288 100 7.0 301 100 6.5 262 100 F 6.9 279 100 7.1 299 100 6.2 265 10016 A 5.8 255 100 5.5 239 100 5.9 244 100 B 5.4 265 100 5.3 249 100 5.3 252 100 C 5.3 266 100 5.1 254 100 5.1 243 100 D 5.9 252 100 5.2 249 100 5.2 239 100 E 5.7 245 100 5.0 238 100 4.9 235 100 F 5.1 246 100 5.3 229 100 5.6 241 100__________________________________________________________________________
TABLE 4__________________________________________________________________________ Curing conditions 20.degree. C. .times. 55% .times. 14 days 20.degree. C. .times. 55% .times. 14 20.degree. C. .times. 55% .times. 14 days Test Conditions 50.degree. C./21 days heatingCompara- Initial in water 100.degree. C./21 daystive Tmax Emax CF Tmax Emax CF Tmax Emax CFExample Adherend (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%) (kgf/cm.sup.2) (%) (%)__________________________________________________________________________5 A 10.2 333 100 7.8 255 80 6.7 301 80 B 9.4 264 90 5.5 171 0 3.4 102 0 C 9.9 299 100 6.7 247 90 6.2 276 70 D 10.4 268 100 7.9 229 50 5.2 133 50 E 9.1 272 100 7.8 239 50 3.8 B8 0 F 8.7 288 70 6.1 122 0 5.5 225 06 A 6.8 233 100 4.1 205 20 5.9 210 80 B 6.1 219 80 3.2 173 0 4.1 215 0 C 6.3 214 80 3.8 195 40 4.3 201 50 D 6.3 212 100 4.0 183 10 4.2 198 60 E 6.6 187 70 2.2 104 40 4.3 109 0 F 6.5 225 50 4.2 95 30 4.5 122 07 A 11.5 380 90 7.0 387 70 8.0 355 80 B 9.7 332 90 7.3 356 0 8.4 362 0 C 11.4 311 90 7.1 356 70 8.1 333 80 D 11.6 324 90 7.5 389 50 8.9 311 50 E 11.2 302 80 7.1 234 60 8.0 321 50 F 10.2 289 80 3.4 102 0 8.2 305 08 A 10.8 322 100 7.5 255 80 8.9 265 80 B 11.1 302 70 3.1 56 0 2.9 48 0 C 10.1 346 100 6.9 215 70 7.7 266 70 D 12.9 316 80 8.1 244 60 8.9 246 60 E 10.4 311 80 7.4 261 60 8.1 259 60 F 9.8 295 70 2.9 46 0 3.2 59 0__________________________________________________________________________
As is evident from Tables 3 and 4, RTV organopolysiloxane compositions within the scope of the invention (Examples 8-16) provide a firm bond to surface treated aluminum plates and mortar and maintain such bond under water immersion and at elevated temperature.
Japanese Patent Application Nos. 348321/1995 and 241439/1996 are incorporated herein by reference.
While the invention has been described in what is presently considered to be a preferred embodiment, other variations and modifications will become apparent to those skilled in the art. It is intended, therefore, that the invention not be limited to the illustrative embodiments, but be interpreted within the full spirit and scope of the appended claims.

Number	Date	Country	Kind
7-348321	Dec 1995	JPX
8-241439	Aug 1996	JPX

Number	Name	Date
5118738	Berthet	Jun 1992
5212010	Curzio et al.	May 1993
5405889	Hatanaka	Apr 1995

RTV organopolysiloxane compositions

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