Rubber tire composition comprising an azo-silane coupling agent
View Patent ↗The invention relates to a tire rubber composition based on at least one diene elastomer, an inorganic filler as reinforcing filler, a coupling agent providing the bonding between the inorganic filler and the diene elastomer, characterized in that the coupling agent is an azosilane compound of following formula (I): (G 1 ) 3-a (G 2 ) a Si—Z—NH—C(O)—N═N—C(O)—NH—Z—Si(G 1 ) 3-a (G 2 ) a (I) in which: G 1 , identical to or different from one another, each represent a monovalent hydrocarbon-based group chosen from branched or unbranched, substituted or unsubstituted alkyls, having from 1 to 18 carbon atoms, substituted or unsubstituted cycloalkyls or aryls, having from 5 to 18 carbon atoms, G 2 , identical to or different from one another, each represent a hydroxyl group or a monovalent group in the form (G 3 ) n -OG 1 in which G 3 is a divalent linking group having from 1 to 18 carbon atoms and comprising one or more heteroatoms chosen from O, S, Si and N, n being a number equal to or higher than 0 and less than or equal to 18, Z represents a divalent linking group having from 1 to 18 carbon atoms, a is equal to 1, 2 or 3.
1. A tire rubber composition based on at least one diene elastomer, an inorganic filler as reinforcing filler, and a coupling agent providing the bonding between the inorganic filler and the diene elastomer, wherein the coupling agent is an azosilane compound of following formula (I)
(G 1 ) 3-a (G 2 ) a Si—Z—NH—C(O)N═N—C(O)—NH—Z—Si(G 1 ) 3-a (G 2 ) a (I)
wherein:
G 1 , identical to or different from one another, each represent a monovalent hydrocarbon group chosen from branched or unbranched, unsubstituted or substituted alkyls, having from 1 to 18 carbon atoms, unsubstituted or substituted cycloalkyls or aryls, having from 5 to 18 carbon atoms,
G 2 , identical to or different from one another, each represent a hydroxyl group or a monovalent group (G 3 ) n -OG 1 in which G 3 is a divalent linking group having from 1 to 18 carbon atoms and comprising one or more heteroatoms chosen from O, S, Si and N, n being a number equal to or higher than 0 and less than or equal to 18, and at least one G 2 represents a monovalent group (G 3 ) n -OG 1 wherein n is higher than 0,
Z represents a divalent linking group having from 1 to 18 carbon atoms,
a is equal to 1, 2 or 3.
2. The composition according to claim 1 , wherein a is equal to 3.
3. The composition according to claim 2 , wherein the azosilane compound of formula (I) is chosen from the following compounds:
(EtO)(RO) 2 Si—CH 2 —CH 2 —CH 2 —NH—CO—N═N—CO—NH—CH 2 —CH 2 —CH 2 —Si(EtO)(RO) 2 , (RO)(EtO) 2 Si—CH 2 —CH 2 —CH 2 —NH—CO—N═N—CO—NH—CH 2 —CH 2 —CH 2 —Si(RO)(EtO) 2 wherein Et=ethyl and R═C 13 H 27 (OCH 2 CH 2 ) 5 .
4. The composition according to claim 1 , wherein Z is chosen from C 1 -C 18 alkylenes and C 6 -C 12 arylenes.
5. The composition according to claim 4 , wherein Z is chosen from C 1 -C 10 alkylenes.
6. The composition according to claim 5 , wherein Z is a propylene.
7. The composition according to claim 5 , wherein Z is C 1 -C 4 alkylene.
8. The composition according to claim 1 , wherein n is equal to or higher than 1 and less than or equal to 18.
9. The composition according to claim 8 , wherein G 3 is a C 1 -C 12 oxy-alkylene.
10. The composition according to claim 9 , wherein G 3 is a C 1 -C 4 oxy-alkylene.
11. The composition according to claim 10 , wherein G 3 is an oxy-ethylene or oxy-propylene.
12. The composition according to claim 1 , wherein the diene elastomer is chosen from the group consisting of polybutadienes, synthetic polyisoprenes, natural rubber, butadiene copolymers, isoprene copolymers and the mixtures of these elastomers.
13. The composition according to claim 1 , wherein the inorganic filler is a filler of the siliceous or aluminous type.
14. The composition according to claim 1 , wherein the amount of reinforcing inorganic filler is greater than 50 phr.
15. The composition according to claim 14 , wherein the amount of reinforcing inorganic filler is greater than 50 phr and less than 140 phr.
16. The composition according to claim 1 , further comprising a second coupling agent.
17. The composition according to claim 16 , wherein the second coupling agent is a silane sulphide compound corresponding to the formula (II):
Y 1 —Z 1 —S x —Z 2 —Y 2 (II) wherein: x is a number from 2 to 8; Z 1 and Z 2 , which are identical or different, each represent a divalent hydrocarbon radical comprising from 1 to 18 carbon atoms; Y 1 and Y 2 , which are identical or different, each correspond to one of the following formulae: wherein: the R 1 radicals, which are unsubstituted or substituted and identical to or different from one another, represent a C 1 -C 18 alkyl, C 5 -C 18 cycloalkyl or C 8 -C 18 aryl group; the R 2 radicals, which are unsubstituted or substituted and identical to or different from one another, represent a hydroxyl, C 1 -C 18 alkoxyl or C 5 -C 18 cycloalkoxyl group.
18. The composition according to claim 17 , wherein Z 1 and Z 2 are chosen from the group consisting of C 1 -C 10 alkylenes.
19. The composition according to claim 18 , wherein Z 1 and Z 2 are propylene.
20. The composition according to claim 18 , wherein Z 1 and Z 2 are C 1 -C 4 alkylene.
21. The composition according to claim 17 , wherein the R 1 radicals are chosen from C 1 -C 4 alkyls.
22. The composition according to claim 21 , wherein the R 1 radicals are methyl.
23. The composition according to claim 17 , wherein the R 2 radicals are chosen from the group consisting of hydroxyl and C 1 -C 4 alkoxyls.
24. The composition according to claim 23 , wherein the R 2 radicals are chosen from the group consisting of hydroxyl, methoxyl, and ethoxyl.
25. The composition according to claim 17 , wherein x is a number from 2 to 5.
26. The composition according to claim 1 , wherein the coupling agent has an overall content that represents between 2% and 20% by weight with respect to the amount of reinforcing inorganic filler.
27. The composition according to claim 26 , wherein the overall content of coupling agent is between 2 and 15 phr.
28. The composition according to claim 27 , wherein the overall content of coupling agent is between 2 and 12 phr.
29. The composition according to claim 26 , wherein the overall content of coupling agent is between 2% and 15% by weight.
30. The composition according to claim 1 , further comprising a covering agent selected from the group consisting of hydroxylated or hydrolysable silanes, polyols, polyethers, esters, amines, hydroxylated or hydrolysable polysiloxanes, and the mixtures of such compounds.
31. The composition according to claim 30 , wherein the covering agent is an α,ω-(dihydroxy)polyorganosiloxane oil.
32. A tire or semi-finished product, comprising a rubber composition according to claim 1 .
33. A tire tread, comprising a rubber composition according to claim 1 .
34. A tire rubber composition based on at least one diene elastomer, an inorganic filler as reinforcing filler, and a coupling agent providing the bonding between the inorganic filler and the diene elastomer, wherein the coupling agent is an azosilane compound of following formula (I)
(G 1 ) 3-a (G 2 ) a Si—Z—NH—C(O)N═N—C(O)—NH—Z—Si(G 1 ) 3-a (G 2 ) a (I)
wherein:
G 1 , identical to or different from one another, each represent a monovalent hydrocarbon group chosen from branched or unbranched, unsubstituted or substituted alkyls, having from 1 to 18 carbon atoms, unsubstituted or substituted cycloalkyls or aryls, having from 5 to 18 carbon atoms,
G 2 , identical to or different from one another, each represent a hydroxyl group or a monovalent group (G 3 ) n -OG 1 in which G 3 is a divalent linking group having from 1 to 18 carbon atoms and comprising one or more heteroatoms chosen from O, S, Si and N, n being a number equal to or higher than 0 and less than or equal to 18,
Z represents a divalent linking group having from 1 to 18 carbon atoms, and wherein Z comprises one or more heteroatoms chosen from O, S, N and Si, and
a is equal to 1, 2 or 3.