Abstract: Polymer particles according to an embodiment includes a (meth)acrylate polymer having a constituent unit represented by the following formula (1) and having a chemically crosslinked structure containing an ether bond or a siloxane bond: wherein R1 is a hydrogen atom or a methyl group, and R2 is an alkyl group having 4 to 18 carbon atoms.

Abstract: A rubber composition according to an embodiment includes: a rubber component comprising diene rubber; and fine particles which are formed of a specific polymer and have a glass transition point of ?70° C. to 0° C. The fine particles are fine particles formed of a (meth)acrylate polymer having a constitutional unit represented by formula (1) or formed of a polymer having a constitutional unit represented by formula (4). In formula (1), R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 4 to 18 carbon atoms. In formula (4), at least one of R11, R12, R13, R14, R15, and R16 represents an aliphatic hydrocarbon group having 3 to 8 carbon atoms, and the remainder represents a hydrogen atom or an aliphatic hydrocarbon group having 1 or 2 carbon atoms.

Abstract: A rubber composition according to an embodiment includes: a rubber component comprising diene rubber; and fine particles which are formed of a specific polymer and have a glass transition point of ?70° C. to 0° C. The fine particles are fine particles formed of a (meth)acrylate polymer having a constitutional unit represented by formula (1) or formed of a polymer having a constitutional unit represented by formula (4). In formula (1), R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 4 to 18 carbon atoms. In formula (4), at least one of R11, R12, R13, R14, R15, and R16 represents an aliphatic hydrocarbon group having 3 to 8 carbon atoms, and the remainder represents a hydrogen atom or an aliphatic hydrocarbon group having 1 or 2 carbon atoms.

Abstract: Disclosed is a copolymer including a monomer unit (a) derived from a compound represented by the formula (1) and a monomer unit (b) derived from a compound represented by the formula (2), and having a weight average molecular weight (Mw) of from 1,000 to 50,000 wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom, a linear alkyl group having from 1 to 8 carbon atoms, or a branched alkyl group having from 3 to 8 carbon atoms, R3, R4, R5, R6, R7 and R8 may be the same or different, at least one of those groups represents an aliphatic hydrocarbon group having from 3 to 8 carbon atoms, and the remainder represents a hydrogen atom or an aliphatic hydrocarbon group having 1 or 2 carbon atoms.

Abstract: A rubber composition contains 100 parts by mass of a rubber component comprising diene rubber, and from 1 to 100 parts by mass of a (meth)acrylate polymer having a weight average molecular weight of from 5,000 to 1,000,000 and a glass transition point of from ?70 to 0° C. A pneumatic tire is obtained using the rubber composition.

Abstract: Disclosed is a copolymer including a monomer unit (a) derived from a compound represented by the formula (1) and a monomer unit (b) derived from a compound represented by the formula (2), and having a weight average molecular weight (Mw) of from 1,000 to 50,000 wherein R1 represents a hydrogen atom or a methyl group, R2 represents a hydrogen atom, a linear alkyl group having from 1 to 8 carbon atoms, or a branched alkyl group having from 3 to 8 carbon atoms, R3, R4, R5, R6, R7 and R8 may be the same or different, at least one of those groups represents an aliphatic hydrocarbon group having from 3 to 8 carbon atoms, and the remainder represents a hydrogen atom or an aliphatic hydrocarbon group having 1 or 2 carbon atoms.