Rubber composition, crosslinked product, and tire
A method for producing a rubber composition may include: mixing modified silica (B), pre-prepared by surface treatment of unmodified silica, with a modified conjugated diene-based polymer (A) and a polymer having crystalline character (C). A crosslinked product may be produced through crosslinking a rubber composition obtained from such a method. The crosslinked product may be used for producing a tire including a tread and a sidewall, wherein at least one of the tread and the sidewall is formed of the crosslinked product.
1. A method for producing a rubber composition, the method comprising:
mixing modified silica (B), pre-prepared by surface treatment of unmodified silica, with a modified conjugated diene-based polymer (A) and a polymer having crystalline character (C).
2. The method of claim 1 , wherein the modified silica (B) is pre-prepared in a pre-preparing comprising:
surface treating the unmodified silica with a silane coupling agent and a hydrophobicizing agent, and thereafter carrying out the mixing.
3. The method of claim 2 , wherein the silane coupling agent comprises a sulfur-comprising organic silane compound, and
wherein the hydrophobicizing agent comprises a fatty acid.
4. The method of claim 2 , wherein the surface treating comprises
reacting the silane coupling agent, comprising a sulfur-comprising organic silane compound and a nitrogen-comprising organic silane compound, with the unmodified silica to obtain a resultant product, and
reacting the resultant product with the hydrophobicizing agent comprising a fatty acid.
5. The method of claim 2 , wherein the silane coupling agent comprises a sulfur-comprising organic silane compound and a hydrocarbyl-group-comprising silane compound.
6. The method of claim 1 , wherein the modified silica (B) comprises an amino group, an amido group, a carboxy group, a carbinol ester group, a mercapto group, and/or a (poly)sulfide group.
7. The method of claim 1 , wherein the polymer having crystalline character (C) has a crystallinity in a range of from 5 to 70%.
8. The method of claim 1 , wherein the polymer having crystalline character (C) comprises 1,2-polybutadiene, polystyrene, polypropylene, polyethylene, and/or ethylene-propylene copolymer.
9. The method of claim 1 , wherein the polymer having crystalline character (C) is at least one selected from the group consisting of 1,2-polybutadiene, polystyrene, polypropylene, polyethylene, and ethylene-propylene copolymer.
10. The method of claim 1 , wherein the polymer having crystalline character (C) comprises syndiotactic 1,2-polybutadiene.
11. The method of claim 1 , wherein the polymer having crystalline character (C) is syndiotactic 1,2-polybutadiene.
12. The method of claim 1 , wherein the modified conjugated diene-based polymer (A) is obtained by a process comprising reacting
a conjugated diene-based polymer comprising an active terminal, and
a compound comprising a functional group capable of reacting with the active terminal and a functional group that interacts with silica.
13. The method of claim 1 , wherein the polymer having crystalline character (C) has a melting point of 50° C. or higher.
14. The method of claim 1 , the mixing comprises adding the modified silica (B) to a kneader to thereby mix the modified silica (B) with the modified conjugated diene-based polymer (A) and the polymer having crystalline character (C) using the kneader.
15. The method of claim 1 , wherein the polymer having crystalline character (C) is present in a range of from 1 to 15 mass %, relative to an entire rubber composition mass.