Conjugated diene rubber, process for producing the same, and rubber composition
A conjugated diene rubber obtained by a process wherein active conjugated diene polymer chains each having an active metal at a polymer chain terminal, which have been obtained by polymerizing a conjugated diene monomer alone, or a conjugated diene monomer and an aromatic vinyl monomer with the aid of an organic active metal in an inert solvent, are allowed to react with a specific polyorganosiloxane capable of reacting with the active metal bonded to the polymer chain terminal. The conjugated diene rubber contains at least 5% by weight of a structure comprising at least three conjugated diene polymer chains bonded through a polyorganosiloxane. The conjugated diene rubber gives, when silica is incorporated therein, a rubber composition having good processability and giving a crosslinked rubber having reduced heat build-up, good wet grip performance and good abrasion resistance.
1. A conjugated diene rubber containing at least 5% by weight of a structure comprising at least three conjugated diene polymer chains bonded through a polyorganosiloxane.
2. The conjugated diene rubber according to claim 1 , wherein the conjugated diene polymer chains comprise 50 to 100% by weight of conjugated diene monomer units and 50 to 0% by weight of aromatic vinyl monomer units.
3. The conjugated diene rubber according to claim 1 , wherein the conjugated diene polymer chains comprise 40 to 99.9% by weight of 1,3-butadiene units, 0.1 to 10% by weight of isoprene units and 0 to 50% by weight of aromatic vinyl monomer units.
4. The conjugated diene rubber according to claim 2 , wherein the conjugated diene monomer units have a vinyl bond content in the range of 10 to 95% by weight.
5. The conjugated diene rubber according to claim 1 , wherein the polyorganosiloxane has 5 to 200 functional groups in the molecule which are capable of reacting with an active metal bonded to a terminal of each active conjugated diene polymer chain.
6. The conjugated diene rubber according to claim 1 , wherein the conjugated diene polymer chains are bonded through a polyorganosiloxane represented by the following general formula (1):
wherein R 1 through R 8 represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and R 1 through R 8 may be the same or different; X 1 and X 4 are either (i) such that a part of the plural X 1 and a part of the plural X 4 are a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, and groups with 4 to 12 carbon atoms containing an epoxy group, and the remainder of the plural X 1 and the remainder of the plural X 4 are a group derived from these groups or are a single bond, or (ii) an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and X 1 and X 4 may be the same or different; X 2 is a group such that a part of the plural X 2 is a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, and groups with 4 to 12 carbon atoms containing an epoxy group, and the remainder of the plural X 2 is a group derived from these groups or is a single bond; X 3 is a group comprising 2 to 20 alkylene glycol repeating units; and m is an integer in the range of 3 to 200, n is an integer in the range of 0 to 200, and k is an integer in the range of 0 to 200.
7. The conjugated diene rubber according to claim 1 , wherein the conjugated diene polymer chains are bonded through a polyorganosiloxane represented by the following general formula (3):
wherein X 2 is a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, and groups with 4 to 12 carbon atoms containing an epoxy group; X 3 is a group comprising 2 to 20 alkylene glycol repeating units; and m is an integer in the range of 5 to 200, n is an integer in the range of 0 to 200, and k is an integer in the range of 0 to 200.
8. The conjugated diene rubber according to claim 1 , wherein the conjugated diene polymer chains are bonded through a polyorganosiloxane represented by the following general formula (4):
wherein R 1 through R 5 represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and R 1 through R 5 may be the same or different; X 1 through X 3 are a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, groups with 4 to 12 carbon atoms containing an epoxy group, and groups Q derived from these groups, and a part of X 1 through X 3 is the group Q, and X 1 through X 3 may be the same or different; and m is an integer in the range of 3 to 200.
9. A rubber composition comprising the conjugated diene rubber as claimed in claim 1 .
10. The rubber composition according to claim 9 , which further comprises silica.
11. A process for producing a conjugated diene rubber as claimed in claim 1 , characterized in that active conjugated diene polymer chains each having an active metal at a polymer chain terminal, which have been obtained by polymerizing a conjugated diene monomer alone, or a conjugated diene monomer and an aromatic vinyl monomer with the aid of an organic active metal in an inert solvent, are allowed to react with a polyorganosiloxane having 5 to 200 functional groups in the molecule which are capable of reacting with the active metal bonded to a terminal of each active conjugated diene polymer chain, wherein the amount of the polyorganosiloxane is larger than 0.00 1 mole but smaller than 0.1 mole, per mole of the organic active metal used in the polymerization.
12. The process for producing a conjugated diene rubber according to claim 11 , wherein the active conjugated diene polymer chains have been obtained by polymerizing a monomer composition comprising 50 to 100% by weight of a conjugated diene monomer and 50 to 0% by weight of an aromatic vinyl monomer.
13. The process for producing a conjugated diene rubber according to claim 11 , wherein the active conjugated diene polymer chains have been obtained by polymerizing a monomer composition comprising 40 to 99.9% by weight of 1,3-butadiene, 0.1 to 10% by weight of isoprene and 0 to 50% by weight of an aromatic vinyl monomer.
14. The process for producing a conjugated diene rubber according to claim 13 , wherein the active conjugated diene polymer chains have been obtained by a polymerization procedure wherein polymerization is carried out with the aid of an organic active metal in an inert solvent by the steps of:
polymerizing a monomer mixture comprising at least 80% by weight of the amount of 1,3-butadiene used for polymerization, not larger than 80% by weight of the amount of isoprene used for polymerization, and at least 80% by weight of the amount of the optional aromatic vinyl monomer used for polymerization;
adding the remainder of the amount of isoprene, followed by polymerization; and then,
adding the remainder of the amount of 1,3-butadiene and the remainder of the amount of the optional aromatic vinyl monomer, followed by polymerization.
15. The process for producing a conjugated diene rubber according to claim 11 , wherein the polyorganosiloxane is represented by the following general formula (2): wherein R 9 through R 16 represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and R 9 through R 16 may be the same or different; X 5 and X 8 are a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, and groups with 4 to 12 carbon atoms containing an epoxy group, and X 5 and X 8 maybe the same or different; X 6 is a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, and groups with 4 to 12 carbon atoms containing an epoxy group; X 7 is a group comprising 2 to 20 alkylene glycol repeating units; and m is an integer in the range of 3 to 200, n is an integer in the range of 0 to 200, and k is an integer in the range of 0 to 200.
16. The process for producing a conjugated diene rubber according to claim 11 , wherein the polyorganosiloxane is represented by the following general formula (3):
wherein X 2 is a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, and groups with 4 to 12 carbon atoms containing an epoxy group; X 3 is a group comprising 2 to 20 alkylene glycol repeating units; and m is an integer in the range of 5 to 200, n is an integer in the range of 0 to 200, and k is an integer in the range of 0 to 200.
17. The process for producing a conjugated diene rubber according to claim 11 , wherein the polyorganosiloxane is represented by the following general formula (5):
wherein R 6 through R 10 represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and R 6 through R 10 may be the same or different; X 4 through X 6 are a group selected from alkoxyl groups having 1 to 5 carbon atoms, hydrocarbon groups containing a 2-pyrrolidonyl group, groups with 4 to 12 carbon atoms containing an epoxy group, and X 4 through X 6 may be the same or different; and m is an integer in the range of 3 to 200.
18. The process for producing a conjugated diene rubber according to claim 11 , wherein the functional groups, which are capable of reacting with an active metal bonded to a terminal of each active conjugated diene polymer chain, are epoxy groups.