US 12,331,178 B2
Rubber compositions
Satoshi Motoda, Tokyo (JP)
Assigned to KURARAY CO., LTD., Okayama (JP)
Appl. No. 17/255,433
Filed by KURARAY CO., LTD., Okayama (JP)
PCT Filed Jun. 21, 2019, PCT No. PCT/JP2019/024630
§ 371(c)(1), (2) Date Dec. 23, 2020,
PCT Pub. No. WO2020/004242, PCT Pub. Date Jan. 2, 2020.
Claims priority of application No. 2018-124663 (JP), filed on Jun. 29, 2018; and application No. 2019-070481 (JP), filed on Apr. 2, 2019.
Prior Publication US 2021/0139666 A1, May 13, 2021
Int. Cl. C08K 3/04 (2006.01); C08C 19/25 (2006.01); C08K 3/36 (2006.01); C08K 5/54 (2006.01); C08L 7/00 (2006.01); C08L 9/00 (2006.01); C08L 15/00 (2006.01); C08L 21/00 (2006.01); C08L 23/16 (2006.01)
CPC C08K 3/04 (2013.01) [C08K 3/36 (2013.01); C08L 9/00 (2013.01); C08L 15/00 (2013.01); C08L 2312/02 (2013.01)] 3 Claims
 
1. A rubber composition comprising a solid rubber (A),a liquid diene rubber (B), a silane coupling agent (C), silica (D) having a BET specific surface area of 30 to 200 m2/g, and a crosslinking agent,
wherein the solid rubber (A) is at least one selected from the group consisting of natural rubbers and ethylene propylene diene rubbers,
the crosslinking agent is a peroxide having a structure represented by the following formula (3), wherein R1 and R2 are each a substituted or unsubstituted, linear or branched, alkyl group having

OG Complex Work Unit Chemistry
1 to 5 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, and
the liquid diene rubber (B) is a modified liquid diene rubber (B1A) that has a functional group that is a partial structure represented by the following formula (2),

OG Complex Work Unit Chemistry
wherein R3 is a C1-C6 divalent alkylene group, and R4, R5 and R6 are each independently a methoxy group, an ethoxy group, a phenoxy group, a methyl group, an ethyl group or a phenyl group, with the proviso that at least one of R4, R5, and R6 is a methoxy group, an ethoxy group or a phenoxy group, and
the average number of the functional groups of the partial structure represented by the formula (2) per molecule of the modified liquid diene rubber (B1A) is 1 to 9, and the weight average molecular weight of the liquid diene rubber (B) is not less than 5,700 and not more than 60,000.