Claims
- 1. A method for preparing a polyalkoxysilyl-terminated polydiorganosiloxane which comprises effecting reaction between the compnents of a mixture comprising at least one silanol-terminated polydiorganosiloxane and an amount effective for endcapping thereof of at least one polyalkoxysilane of the formula
- (R.sup.1).sub.a Si(OR.sup.2).sub.4-a ( 1)
- wherein R.sup.1 is an unsubstituted or substituted hydrocarbon radical containing from 1 to about 13 carbon atoms, R.sup.2 is an alkyl, alkoxyalkyl, acylalkyl, acyloxyalkyl or cyanoalkyl radical containing from 1 to about 8 carbon atoms or an aralkyl radical containing from 1 to about 14 carbon atoms, and a is for 0 or 1; said reaction being conducted in the presence of a catalytic amount of an acidic amine salt which subsequently decomposes to substantially inert products, and said mixture being free of silicon-nitrogen compounds and enoxysilanes.
- 2. A method according to claim 1 wherein the acidic salt is an amine salt of formic acid.
- 3. A method according to claim 2 wherein the silanol-terminated polydiorganosiloxane has the formula ##STR8## wherein each R.sup.3 is independently an unsubstituted or substituted hydrocarbon radical containing about 1-13 carbon atoms and n is in the range of about 5-5000.
- 4. A method according to claim 3 wherein the amine is a dialkylamine.
- 5. A method according to claim 4 wherein each R.sup.3 is methyl and the polyalkoxysilane is methyltrimethoxysilane and is employed in the amount of about 0.5-10.0 parts by weight per 100 parts of silanol-terminated polydiorganosiloxane.
- 6. A method according to claim 5 wherein the amine salt of formic acid is employed in the amount of about 0.005-3.0 parts by weight per 100 parts of silanol-terminated polydiorganosiloxane.
- 7. A method according to claim 6 wherein the amine is di-n-butylamine.
- 8. A method according to claim 6 wherein the amine is diisobutylamine.
- 9. A method according to claim 6 wherein the amine salt and methyltrimethoxysilane are employed in the amounts of about 0.05-0.30 and about 0.5-3.0 parts, respectively, per 100 parts of silanol-terminated polydiorganosiloxane.
- 10. A method according to claim 5 wherein the amine salt of formic acid is prepared in situ in said mixture by the addition of formic acid and an amine.
- 11. A method according to claim 10 wherein the amine and formic acid are employed in the amounts of about 0.001-1.0 part and about 0.001-0.1 part by weight, respectively, per 100 parts of silanol-terminated polydiorganosiloxane.
- 12. A composition characterized by a viscosity decrease of 50% or less when stored for 3 days at 100.degree. C., said composition comprising polyalkoxysilyl-terminated polydiorganosiloxanes and substantially inert decomposition products of an acidic amine salt and being free of silicon-nitrogen compounds and enoxysilanes; said polyalkoxysilyl-terminated polydiorganosiloxanes having the formula ##STR9## wherein R.sup.1 is an unsubstituted or substituted hydrocarbon radical containing from 1 to about 13 carbon atoms, R.sup.2 is an alkyl, alkoxyalkyl, acylalkyl, acyloxyalkyl or cyanoalkyl radical containing from 1 to about 8 carbon atoms or an aralkyl radical containing from 1 to about 14 carbon atoms, and a is 0 or 1.
- 13. A composition according to claim 12 which comprises polymethoxysilyl-terminated polydimethylsiloxanes.
- 14. An enoxysilane-free room temperature vulcanizable polydiorganosiloxane composition comprising:
- (A) a composition according to claim 12, and
- (B) a catalytic amount of an organotin complex of the formula ##STR10## wherein R.sup.4 is an unsubstituted or substituted hydrocarbon radical containing from 1 to about 18 carbon atoms and each of R.sup.5, R.sup.6 and R.sup.7 is independently hydrogen, R.sup.4, Si(R.sup.4).sub.3, acyl or nitrile.
- 15. A composition according to claim 14 which also contains, as an adhesion promoter, (C) an effective amount of at least one compound selected from the group consisting of N-trialkoxysilyalkyl-substituted amides and imides, N-mono(trialkoxysilylalkyl)-substituted ureas, N,N'-bis(trialkoxysilylalkyl)-substituted ureas, trialkoxysilylalkyl isocyanurates, mono-(N-trialkoxysilylalkyl)alkylenediamines, and combinations thereof with (D) a cyanoalkyltrialkoxysilane, said adhesion promoter and any reaction products thereof being the only silicon-nitrogen compounds in said composition.
- 16. A composition according to claim 15 wherein component B is dibutyltin bis(acetylacetonate) and is employed in the amount of about 0.1-10.0 parts by weight per 100 parts of component A.
- 17. A composition according to claim 16 wherein component C is employed in the amount of about 0.1-5.0 parts by weight per 100 parts of component A.
- 18. A composition according to claim 17 wherein component C is tris(3-trimethoxysilylpropyl) isocyanurate, N-(3-trimethoxysilylpropyl)urea or N,N'-bis(3-trimethoxysilylpropyl)urea.
- 19. A composition according to claim 17 wherein component C is N-(3-trimethoxysilylpropyl)-p-nitrobenzamide, N-(3-trimethoxysilylpropyl)maleimide or N-(3-trimethoxysilylpropyl)ethylenediamine, and component D is 2-cyanoethyltrimethoxysilane and is employed in the amount of about 0.1-5.0 parts by weight per 100 parts of component A.
- 20. A composition according to claim 17 which also comprises at least one of the following, all proportions being per 100 parts of component A:
- (E) about 0.05-5.0 parts of a diketone of the formula ##STR11## (F) about 0.01-10.0 parts of at least one polyalkoxysilane of the formula
- (R.sup.1).sub.a Si(OR.sup.2).sub.4-a ( 1)
- wherein R.sup.1 is an unsubstituted or substituted hydrocarbon radical containing from 1 to about 13 carbon atom, R.sup.2 is an alkyl, alkoxyalkyl, acylalkyl, acyloxyalkyl or cyanoalkyl radical containing from 1 to about 8 carbon atoms or an aralkyl radical containing from 1 to about 14 carbon atoms, and a is 0 or 1;
- (G) about 1-50 parts of a plasticizer comprising a trialkylsilyl-terminated polydiorganosiloxane of the formula ##STR12## wherein R.sup.3 is an unsubtituted or substituted hydrocarbon radical containing about 1-13 carbon atoms and m is in the range of about 25-5000;
- (H) about 5-700 parts of at least one filler;
- (J) about 0.1-5.0 parts of an amine as a curing accelerator.
- 21. A composition according to claim 20 which includes components E, F and G.
- 22. A composition according to claim 20 wherein R.sup.1-3, R.sup.5 and R.sup.7 are each methyl, R.sup.4 is n-butyl, R.sup.6 is hydrogen and a is 1.
Parent Case Info
This application is a continuation-in-part of copending application Ser. No. 090,183, filed Aug. 27, 1987, now abandoned.
US Referenced Citations (6)
Continuation in Parts (1)
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Number |
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90183 |
Aug 1987 |
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