Tire rubber composition
The present technology provides a tire rubber composition formed by blending a microparticle composite, which is formed from a solid component of a mixture containing an emulsion of an organic microparticle and a rubber latex, in a sulfur vulcanizable rubber; the emulsion of the organic microparticle being an emulsion containing a microparticle obtained by polymerizing and/or crosslinking at least one selected from the group consisting of polymerizable monomers, and oligomers, prepolymers, and polymers having a reactive functional group and having a molecular weight from 500 to 50000 simultaneously or stepwise in water; and an average particle size of the microparticle being from 0.001 to 100 μm.
1. A tire rubber composition comprising a microparticle composite in a sulfur vulcanizable rubber; the microparticle composite being a solid component of a mixture formed from an emulsion of an organic microparticle and a rubber latex; the emulsion of the organic microparticle being an emulsion containing a microparticle obtained by polymerizing and/or crosslinking at least one selected from the group consisting of polymerizable monomers, and oligomers, prepolymers, and polymers having a reactive functional group and having a molecular weight from 500 to 50000 simultaneously or stepwise in water; and an average particle size of the microparticle being from 0.001 to 100 μm.
2. The tire rubber composition according to claim 1 , wherein the at least one selected from the group consisting of oligomers, prepolymers, and polymers has at least one selected from the group consisting of a mercapto group, a sulfur atom, and polysulfide bonds containing at least two sulfur atoms.
3. The tire rubber composition according to claim 1 , wherein the at least one selected from the group consisting of oligomers, prepolymers, and polymers has at least one other reactive functional group except the group consisting of a mercapto group, a sulfur atom, and polysulfide bonds containing at least two sulfur atoms.
4. The tire rubber composition according to claim 1 , wherein the oligomers, the prepolymers, and the polymers each have a backbone selected from the group consisting of polycarbonate-based, aliphatic-based, saturated hydrocarbon-based, and acrylic polymers, and copolymers of these.
5. The tire rubber composition according to claim 1 , wherein at least one of the polymerizable monomer has at least one selected from the group consisting of a mercapto group, a sulfur atom, and polysulfide bonds containing at least two sulfur atoms.
6. The tire rubber composition according to claim 1 , comprising from 1 to 100 parts by mass of the organic microparticle per 100 parts by mass total of the sulfur vulcanizable rubber and a solid content that is derived from the rubber latex.
7. The tire rubber composition according to claim 1 , wherein a ratio W1/W2 of a mass W1 of the sulfur vulcanizable rubber to a mass W2 of the solid component derived from the rubber latex is in a range from 95/5 to 50/50.
8. The tire rubber composition according to claim 1 , wherein the rubber latex is a natural rubber latex or a synthetic rubber latex.
9. The tire rubber composition according to claim 1 , wherein the solid component derived from the rubber latex is 30 mass % or greater in the rubber latex, and a ratio W2/W3 of a mass W2 of the solid component derived from the rubber latex to a mass W3 of the organic microparticle is in a range from 1/4 to 4/1.
10. The tire rubber composition according to claim 1 , further comprising a compounding agent, the compounding agent being at least one selected from the group consisting of carbon blacks, white fillers, vulcanizing agents, vulcanization accelerators, softeners, oils, anti-aging agents, antioxidants, vulcanization retarders, and silane coupling agents.
11. A pneumatic tire comprising a tire tread formed from the tire rubber composition described in claim 1 .
12. A method of producing a tire rubber composition, the method comprising:
a step of preparing an emulsion of an organic microparticle by polymerizing and/or crosslinking at least one selected from the group consisting of polymerizable monomers, and oligomers, prepolymers, and polymers having a reactive functional group and having a molecular weight from 500 to 50000 simultaneously or stepwise in water to form a microparticle having an average particle size of 0.001 to 100 μm;
a step of preparing a microparticle composite by mixing the emulsion of the organic microparticle with a rubber latex to obtain a mixture, and then removing water of the mixture; and
a step of blending the microparticle composite with a sulfur vulcanizable rubber.
13. The tire rubber composition according to claim 2 , wherein the at least one selected from the group consisting of oligomers, prepolymers, and polymers has at least one other reactive functional group except the group consisting of a mercapto group, a sulfur atom, and polysulfide bonds containing at least two sulfur atoms.
14. The tire rubber composition according to claim 13 , wherein the oligomers, the prepolymers, and the polymers each have a backbone selected from the group consisting of polycarbonate-based, aliphatic-based, saturated hydrocarbon-based, and acrylic polymers, and copolymers of these.
15. The tire rubber composition according to claim 14 , wherein at least one of the polymerizable monomer has at least one selected from the group consisting of a mercapto group, a sulfur atom, and polysulfide bonds containing at least two sulfur atoms.
16. The tire rubber composition according to claim 15 , comprising from 1 to 100 parts by mass of the organic microparticle per 100 parts by mass total of the sulfur vulcanizable rubber and a solid content that is derived from the rubber latex.
17. The tire rubber composition according to claim 16 , wherein a ratio W1/W2 of a mass W1 of the sulfur vulcanizable rubber to a mass W2 of the solid component derived from the rubber latex is in a range from 95/5 to 50/50.
18. The tire rubber composition according to claim 17 , wherein the rubber latex is a natural rubber latex or a synthetic rubber latex.
19. The tire rubber composition according to claim 18 , wherein the solid component derived from the rubber latex is 30 mass % or greater in the rubber latex, and a ratio W2/W3 of a mass W2 of the solid component derived from the rubber latex to a mass W3 of the organic microparticle is in a range from 1/4 to 4/1.
20. The tire rubber composition according to claim 19 , further comprising a compounding agent, the compounding agent being at least one selected from the group consisting of carbon blacks, white fillers, vulcanizing agents, vulcanization accelerators, softeners, oils, anti-aging agents, antioxidants, vulcanization retarders, and silane coupling agents.