Cyclic aminoalkylsilanes and their use as adhesion promoters in room temperature vulcanizable polydiorganosiloxane compositions

Abstract

Cyclic aminoalkylsilane compositions are prepared by the reaction of approximately equimolar amounts of an aminoalkyltrialkoxysilane such as 3-aminopropyltrimethoxy-silane and a glycidyl ether such as methyl glycidyl ether. They are useful as adhesion promotors in room temperature vulcanizable compositions comprising polyalkoxysilyl-terrninated polydiorganosiloxanes.

What is claimed is: 
     
       1. A method for improving adhesion to a substrate of a room temperature vulcanizable composition comprising a polyalkoxy-terminated polydioganosiloxane and a catalytic amount of a curing catalyst, said method comprising incorporating therein an adhesion improving amount of a cyclic aminoalkysilane having the formula ##STR8## wherein R 1  is C 1-8  alkyl, each R 2  is independently hydrogen or C 1-4  primary or secondary alkyl, R 3  is methyl or ethyl and n is 2 or 3. 
     
     
       2. A method according to claim 1 wherein the substrate is aluminum or steel. 
     
     
       3. A method according to claim 2 wherein about 0.1-5.0 parts by weight of said compound is employed per 100 parts of said polydiorganosiloxane. 
     
     
       4. A method according to claim 3 wherein R 1  is methyl, R 2  is hydrogen, R 3  is methyl and n is 3. 
     
     
       5. A room temperature vulcanizable composition comprising (A) at least one polyalkoxy-terminated polydiorganosiloxane, (B) a catalytic amount of a curing catalyst, and (C) an amount of effective to enhance adhesion to a substrate of a cyclic aminoalkylsilane having the formula ##STR9## wherein R 1  is C 1-8  alkyl, each R 2  is independently hydrogen or C 1-4  primary of secondary alkyl, R 3  is methyl or ethyl and n is 2 or 3. 
     
     
       6. A composition according to claim 5 wherein component B is an aluminum, titanium or tin compound and is employed in the amount of about 0.1-10.0 parts by weight per 100 parts of component A. 
     
     
       7. A composition according to claim 6 wherein component B is an organotin complex of the formula ##STR10## wherein R 7  is an unsubstituted or substituted hydrocarbon radical containing from 1 to about 18 carbon atoms and each of R 8 , R 9  and R  10  is independently hydrogen, R 7 , Si(R 7 ) 3 , acyl or nitrile. 
     
     
       8. A composition according to claim 7 wherein about 0.1-10.0 parts of component B and about 0.1-5.0 parts of component C are employed per 100 parts of component A. 
     
     
       9. A composition according to claim 8 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.4).sub.a Si(OR.sup.5).!. (.Iadd.R.sup.4).sub.a Si(OR.sup.5).sub.4-a .Iaddend.                            (VII)     wherein R 4  is an unsubstituted or substituted hydrocarbon radical containing from 1 to about 13 carbon atoms, R 5  is an alkyl, alkoxyalkyl, acylalkyl, acyloxyalkyl or cyanoalkyl radical containing from 1 to about 8 carbon atoms or an aralkyl radical containing from . .1.!. .Iadd.7 .Iaddend.to about 14 carbon atoms, and a is 0 or 1;     (G) about 1-50 parts of a plasticizer;   (H) about 5-700 parts of at least one filler; and   (J) about 0.1-5.0 parts of an amine or guanidine as a curing accelerator.   
     
     
       10. A composition according to claim 9 wherein R 4 , R 5  and R 6  are each methyl. 
     
     
       11. A composition according to claim 10 which also comprises (D) a cyanoalkyltrialkoxysilane in the amount of about 0.1-5.0 parts per 100 pans of component A. 
     
     
       12. A composition according to claim 11 wherein R 7  is butyl, R 8  and R 10 are each methyl and R 9  is hydrogen. 
     
     
       13. A composition according to claim 12 which also comprises components E, F and G, wherein component G is at least one trialkylsilyl-terminated polydiorganosiloxane of the formula ##STR12## wherein R 6  is an unsubstituted or substituted hydrocarbon radical containing about 1-13 carbon atoms. 
     
     
       14. A composition according to claim 6 wherein component A is represented by the formula ##STR13## wherein R 4  is an unsubstituted or substituted hydrocarbon radical containing from 1 to about 13 carbon atoms, R 5  is an alkyl, alkoxyalkyl, acylalkyl, acyloxyalkyl or cyanoalkyl radical from 1 to about 8 carbon atoms or an arylalkyl radical containing from . .1.!. .Iadd.7 .Iaddend. to about 14 carbon atoms, each R 6  is independently an unsubstituted or substituted hydrocarbon radical containing about 1-13 carbon atoms, a is 0 or 1 and m is in the range of about 5-5000.