Hydrolysable silanes and elastomer compositions containing them
View Patent ↗This invention relates to hydrolysable silanes useful in the modification of elastomers, and as coupling agents for diene elastomer compositions containing a filler. In particular the invention relates to novel hydrolysable silanes containing a piperazine ring and an ether or thioether linkage.
1. A hydrolysable silane of the formula
wherein each R represents a hydrolysable group; each R″ represents a hydrocarbyl group having 1 to 8 carbon atoms; n =1 to 3; Y represents a divalent organic spacer linkage having 1 to 20 carbon atoms; m =0 or 1; the piperazine ring (“Pip”) is optionally substituted on his carbon atoms and bonded through its nitrogen atoms; Z represents an oxygen or sulphur atom; o is 0 or 1; R 1 represents a hydrocarbyl or substituted hydrocarbyl group having 1 to 20 carbon atoms: R 2 represents hydrogen or a hydrocarbyl or substituted hydrocarbyl group having 1 to 8 carbon atoms and m+o is 1 or 2.
2. A hydrolysable silane according to claim 1 , characterised in that Z represents a sulphur atom and R 1 represents a group of the formula —Y′—SiR p R″ 3-p wherein Y′ represents a divalent organic spacer linkage having 1 to 20 carbon atoms; each R represents a hydrolysable group; each R″ represents a hydrocarbyl group having 1 to 8 carbon atoms; and p =1 to 3.
3. A hydrolysable silane according to claim 2 , characterised in that m =1 and Y and Y′ each represent an alkylene group having 2 to 6 carbon atoms.
4. A hydrolysable silane according to claim 1 , characterised in that Z represents an oxygen atom and R 1 represents a hydrocarbyl group having 1 to 8 carbon atoms.
5. A hydrolysable silane according to claim 1 , characterised in that m =0 and Y represents an alkylene group having 2 to 6 carbon atoms.
6. A hydrolysable silane according to claim 1 , characterised in that R 2 represents hydrogen.
7. A hydrolysable silane according to claim 1 , characterised in that the 2-,3-,5- and 6-positions on the piperazine ring are unsubstituted.
8. A hydrolysable silane according to claim 1 , characterised in that each group R is an alkoxy group having 1 to 4 carbon atoms, n =3 and p if present is 3 too, or each group R is an alkoxy group having 1 to 4 carbon atoms and n =3 and p if present is 3 too.
9. A hydrolysable silane according to claim 1 , characterised in that the silane is partially hydrolysed and condensed into oligomers containing siloxane linkages.
10. A process for modifying a polymeric material having a carbon backbone containing carbon-to-carbon unsaturation by reaction with a hydrolysable silane, characterised in that the hydrolysable silane is a hydrolysable silane as defined in claim 1 .
11. A process according to claim 10 , characterised in that the polymeric material is a diene elastomer.
12. A process according to claim 10 characterised in that the polymeric material is carbon fibre or carbon black.
13. A diene elastomer composition comprising a diene elastomer, a hydrolysable silane and a curing agent for the diene elastomer, characterised in that the hydrolysable silane is a hydrolysable silane as defined in claim 1 .
14. A composition according to claim 13 characterised in that the hydrolysable silane is present at 0.5 to 15.0% by weight based on the diene elastomer.
15. A composition according to claim 13 characterised in that a filler is present in the composition, whereby the hydrolysable silane acts as a coupling agent between the filler and the diene elastomer.
16. A composition according to claim 13 characterised in that the curing agent for the diene elastomer is sulfur or a sulfur compound.
17. A process for the production of a rubber article characterized in that an elastomer composition according to claim 13 is shaped and cured.
18. A hydrolyzable silane selected from the group consisting of (EtO) 3 Si(CH 2 ) 3 SCH 2 PipCH 2 S(CH 2 ) 3 Si(OEt) 3 , (EtO) 3 Si(CH 2 ) 3 SCH 2 Pip(CH 2 ) 3 Si(OEt) 3 , and EtOCH 2 Pip(CH 2 ) 3 Si(OEt) 3 , where Pip is equal to
19. A process for the preparation of a hydrolysable silane of the formula
in which each R represents a hydrolysable group; each R″ represents a hydrocarbyl group having 1 to 8 carbon atoms; n =1 to 3; Y represents a divalent organic spacer linkage having 1 to 20 carbon atoms; The piperazine ring (“Pip”) is optionally substituted and bonded through its nitrogen atoms; Z represents an oxygen or sulphur atom; o is equal to 1;
R 1 represents a hydrocarbyl or substituted hydrocarbyl group having 1 to 20 carbon atoms and R 2 represents hydrogen or a hydrocarbyl or substituted hydrocarbyl group having 1 to 8 carbon atoms, characterised in that a 1-silylalkyl-1,4-piperazine of the formula H-Pip-Y—SiR n R″ 3-n wherein R, R″, n, and Y are defined as above is reacted with an aldehyde of the formula R 2 —CHO wherein R 2 represents hydrogen or a hydrocarbyl or substituted hydrocarbyl group having 1 to 8 carbon atoms and an alcohol or thiol of the formula R 1 ZH wherein Z represents an oxygen or sulphur atom; and R 1 represents a hydrocarbyl or substituted hydrocarbyl group having 1 to 20 carbon atoms.
20. A process for the preparation of a hydrolysable silane of the formula
in which each R represents a hydrolysable group; each R″ represents a hydrocarbyl group having 1 to 8 carbon atoms; n =1 to 3; and Y represents a divalent organic spacer linkage having 1 to 20 carbon atoms, characterised in that a thioalkyl alkoxysilane of the formula HS—Y—SiR n R″ 3-n wherein R, R″, n, and Y are defined as above is reacted with piperazine and formaldehyde.