RUBBER COMPOSITION AND TIRE USING THE SAME

• US 20100179274A1
• Filed: 08/30/2006
• Published: 07/15/2010
• Est. Priority Date: 09/15/2005
• Status: Active Grant

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Jinbo, Naohisa, Mori, Noriko
• Granted Patent: US 8,426,513 B2
• Time in Patent Office: Days
• US Class Current: 524/516
• CPC Class Codes: B60C 1/00 Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
• CPC Class Codes: B60C 1/0016 Compositions of the tread
• CPC Class Codes: C08C 19/44 of polymers containing metal atoms exclusively at one or both ends of the skeleton
• CPC Class Codes: C08K 3/013 Fillers, pigments or reinforcing additives
• CPC Class Codes: C08K 3/36 Silica
• CPC Class Codes: C08L 15/00 Compositions of rubber derivatives C08L11/00, C08L13/00 take precedence
• CPC Class Codes: C08L 21/00 Compositions of unspecified rubbers
• CPC Class Codes: C08L 25/10 with conjugated dienes
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 2666/08 Homopolymers or copolymers according to C08L7/00 - C08L21/00; Derivatives thereof
• CPC Class Codes: C08L 35/06 Copolymers with vinyl aromatic monomers
• CPC Class Codes: C08L 7/00 Compositions of natural rubber
• CPC Class Codes: C08L 9/06 Copolymers with styrene

Abstract

This invention provides a rubber composition having excellent workability, fracture characteristics and wear resistance and low heat buildup, which comprises not less than 20 parts by mass of a reinforcing filler (B) and 5 to 60 parts by mass of a modified aromatic vinyl compound-conjugated diene compound copolymer (C) having at least one functional group, an aromatic vinyl compound content of 5 to 80% by mass, a vinyl bond content in a conjugated diene compound portion of 10 to 80% by mass and a weight average molecular weight as measured through a gel permeation chromatography and converted to polystyrene of 5,000 to 500,000 based on 100 parts by mass of a rubber component (A) containing not less than 10% by mass of a modified conjugated diene-based polymer having at least one functional group.

Claims

1. A rubber composition comprising not less than 20 parts by mass of a reinforcing filler (B) and 5 to 60 parts by mass of a modified aromatic vinyl compound-conjugated diene compound copolymer (C) having at least one functional group, an aromatic vinyl compound content of 5 to 80% by mass, a vinyl bond content in a conjugated diene compound portion of 10 to 80% by mass and a weight average molecular weight as measured through a gel permeation chromatography and converted to polystyrene of 5,000 to 500,000 based on 100 parts by mass of a rubber component (A) containing not less than 10% by mass of a modified conjugated diene-based polymer having at least one functional group.

2. A rubber composition according to claim 1, wherein an aromatic vinyl compound in the modified aromatic vinyl compound-conjugated diene compound copolymer (C) is styrene.

3. A rubber composition according to claim 1, wherein a conjugated diene compound in the modified aromatic vinyl compound-conjugated diene compound copolymer (C) is butadiene.

4. A rubber composition according to claim 1, wherein the modified aromatic vinyl compound-conjugated diene compound copolymer (C) is a solution-polymerized styrene-butadiene copolymer rubber.

5. A rubber composition according to claim 1, wherein the modified aromatic vinyl compound-conjugated diene compound copolymer (C) has a weight average molecular weight as measured through a gel permeation chromatography and converted to polystyrene of 20,000 to 400,000.

6. A rubber composition according to claim 5, wherein the modified aromatic vinyl compound-conjugated diene compound copolymer (C) has a weight average molecular weight as measured through a gel permeation chromatography and converted to polystyrene of 50,000 to 400,000.

7. A rubber composition according to claim 1, wherein a weight average molecular weight of the modified aromatic vinyl compound-conjugated diene compound copolymer prior to the introduction of the functional group is 5,000 to 300,000 as measured through a gel permeation chromatography and converted to polystyrene.

8. A rubber composition according to claim 7, wherein the weight average molecular weight of the modified aromatic vinyl compound-conjugated diene compound copolymer prior to the introduction of the functional group is 20,000 to 200,000 as measured through a gel permeation chromatography and converted to polystyrene.

9. A rubber composition according to claim 8, wherein the weight average molecular weight of the modified aromatic vinyl compound-conjugated diene compound copolymer prior to the introduction of the functional group is 50,000 to 150,000 as measured through a gel permeation chromatography and converted to polystyrene.

10. A rubber composition according to claim 1, wherein the modified aromatic vinyl compound-conjugated diene compound copolymer (C) has a weight average molecular weight lower than that of the modified conjugated diene-based polymer in the rubber component (A).

11. A rubber composition according to claim 1, wherein the functional group of the modified aromatic vinyl compound-conjugated diene compound copolymer (C) has an affinity for the reinforcing filler.

12. A rubber composition according to claim 11, wherein the functional group of the modified aromatic vinyl compound-conjugated diene compound copolymer (C) is a nitrogen-containing functional group.

13. A rubber composition according to claim 12, wherein the nitrogen-containing functional group is a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, isocyanate group or pyridyl group.

14. A rubber composition according to claim 12, wherein the nitrogen-containing functional group is selected from the group consisting of a substituted amino group represented by the following formula (I):

(wherein R¹ is independently an alkyl group having a carbon number of 1-12, a cycloalkyl group or an aralkyl group) and a cyclic amino group represented by the following formula (II);

(wherein R² is an alkylene group having 3-16 methylene groups, a substituted alkylene group, an oxyalkylene group or a N-alkylamino-alkylene group).

15. A rubber composition according to claim 1, wherein the modified aromatic vinyl compound-conjugated diene compound copolymer (C) is obtained by reacting an active terminal of an aromatic vinyl compound-conjugated diene compound copolymer having an active terminal with at least one selected from the group consisting of a hydrocarbyloxy silane compound represented by the following formula (III):

[wherein A¹ is a monovalent group having at least one functional group selected from (thio)epoxy, (thio)isocyanate, (thio)ketone, (thio)aldehyde, imine, amide, isocyanuric acid triester, (thio)carboxylic acid hydrocarbylester, a metal salt of (thio)carboxylic acid, carboxylic anhydride, a halide of carboxylic acid and carbonic acid dihydrocarbylester;

R³ and R⁴ are independently a monovalent aliphatic hydrocarbon group having a carbon number of 1-20 or a monovalent aromatic hydrocarbon group having a carbon number of 6-18;

R⁵ is a single bond or a bivalent inactive hydrocarbon group having a carbon number of 1-20;

n is an integer of 1-3;

when plural OR³s are existent, they may be same or different; and

active proton and onium salt are not included in the molecule] and a hydrocarbyloxy silane compound represented by the following formula (IV);

R⁶_p—

Si—

(OR⁷)_4-p 

 

(IV)

(wherein R⁶ and R⁷ are independently a monovalent aliphatic hydrocarbon group having a carbon number of 1-20 or a monovalent aromatic hydrocarbon group having a carbon number of 6-18;

p is an integer of 0-2;

when plural OR⁷s are existent, they may be same or different; and

active proton and onium salt are not included in the molecule).

16. A rubber composition according to claim 1, wherein the modified aromatic vinyl compound-conjugated diene compound copolymer (C) has at least one tin-carbon bond or silicon-carbon bond derived from a coupling agent represented by the following formula (V):

R⁸_aZX_b 

 

(V)

(wherein R⁸ is independently selected from the group consisting of an alkyl group having a carbon number of 1-20, a cycloalkyl group having a carbon number of 3-20, an aryl group having a carbon number of 6-20 and an aralkyl group having a carbon number of 7-20;

Z is tin or silicon;

X is independently chlorine or bromine; and

a is 0-3 and b is 1-4 provided that a+b=4).

17. A rubber composition according to claim 1, wherein an amount of the modified aromatic vinyl compound-conjugated diene compound copolymer (C) compounded is not less than 20 parts by mass based on 100 parts by mass of the rubber component (A).

18. A rubber composition according to claim 1, wherein the reinforcing filler (B) is carbon black and/or silica.

19. A rubber composition according to claim 18, wherein an amount of carbon black compounded is not less than 50 parts by mass based on 100 parts by mass of the rubber component (A).

20. A rubber composition according to claim 18, wherein an amount of silica compounded is not less than 50 parts by mass based on 100 parts by mass of the rubber component (A).

21. A rubber composition according to claim 1, wherein the modified conjugated diene-based polymer in the rubber component (A) is a copolymer of 1,3-butadiene and an aromatic vinyl compound or a homopolymer of 1,3-butadiene.

22. A rubber composition according to claim 21, wherein the aromatic vinyl compound is styrene.

23. A rubber composition according to claim 1, wherein the modified conjugated diene-based polymer in the rubber component (A) has a glass transition point (Tg) of not higher than 0°

C.

24. A rubber composition according to claim 1, wherein the modified conjugated diene-based polymer in the rubber component (A) is formed through a polymerization using an organic alkaline metal compound or a rare-earth metal compound.

25. A rubber composition according to claim 24, wherein the organic alkaline metal compound is an alkyl lithium.

26. A rubber composition according to claim 1, wherein the functional group of the modified conjugated diene-based polymer in the rubber component (A) has an affinity for the reinforcing filler (B).

27. A rubber composition according to claim 26, wherein the functional group of the modified conjugated diene-based polymer in the rubber component (A) is a nitrogen-containing functional group.

28. A rubber composition according to claim 27, wherein the nitrogen-containing functional group is a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrite group, isocyanate group or pyridyl group.

29. A rubber composition according to claim 27, wherein the nitrogen-containing functional group is selected from the group consisting of a substituted amino group represented by the following formula (I):

(wherein R¹ is independently an alkyl group having a carbon number of 1-12, a cycloalkyl group or an aralkyl group) and a cyclic amino group represented by the following formula (II);

(wherein R² is an alkylene group having 3-16 methylene groups, a substituted alkylene group, an oxyalkylene group or a N-alkylamino-alkylene group).

30. A rubber composition according to claim 1, wherein the modified conjugated diene-based polymer in the rubber component (A) is obtained by reacting an active terminal of a conjugated diene-based polymer having an active terminal with at least one selected from the group consisting of a hydrocarbyloxy silane compound represented by the following formula (III):

(wherein A¹ is a monovalent group having at least one functional group selected from (thio)epoxy, (thio)isocyanate, (thio)ketone, (thio)aldehyde, imine, amide, isocyanuric acid triester, (thio)carboxylic acid hydrocarbylester, a metal salt of (thio)carboxylic acid, carboxylic anhydride, a halide of carboxylic acid and carbonic acid dihydrocarbylester;

R³ and R⁴ are independently a monovalent aliphatic hydrocarbon group having a carbon number of 1-20 or a monovalent aromatic hydrocarbon group having a carbon number of 6-18;

R⁵ is a single bond or a bivalent inactive hydrocarbon group having a carbon number of 1-20;

n is an integer of 1-3;

when plural OR³s are existent, they may be same or different; and

active proton and onium salt are not included in the molecule) and a hydrocarbyloxy silane compound represented by the following formula (IV);

R⁶_p—

Si—

(OR⁷)_4-p 

 

(IV)

(wherein R⁶ and R⁷ are independently a monovalent aliphatic hydrocarbon group having a carbon number of 1-20 or a monovalent aromatic hydrocarbon group having a carbon number of 6-18;

p is an integer of 0-2;

when plural OR⁷s are existent, they may be same or different; and

active proton and onium salt are not included in the molecule).

31. A rubber composition according to claim 1, wherein the modified conjugated diene-based polymer in the rubber component (A) has at least one tin-carbon bond or silicon-carbon bond derived from a coupling agent represented by the following formula (V):

R⁸_aZX_b 

 

(V)

(wherein R⁸ is independently selected from the group consisting of an alkyl group having a carbon number of 1-20, a cycloalkyl group having a carbon number of 3-20, an aryl group having a carbon number of 6-20 and an aralkyl group having a carbon number of 7-20;

Z is tin or silicon;

X is independently chlorine or bromine; and

a is 0-3 and b is 1-4 provided that a+b=4).

32. A rubber composition according to claim 1, wherein the rubber component (A) contains natural rubber and/or polyisoprene rubber.

33. A tire using a rubber composition as claimed in claim 1.