The present invention aims to provide a photocurable resin composition which rapidly cures by irradiation with active energy rays such as ultraviolet rays and is excellent in adhesion to an electrolyte membrane which is a hard-to-bond material. A photocurable resin composition includes the following ingredients (A) to (C): ingredient (A): a polymer having one or more (meth)acryloyl groups and having a polyisobutylene skeleton containing a [CH.sub.2C(CH.sub.3).sub.2] unit, ingredient (B): a photoradical polymerization initiator, and ingredient (C): a compound having a (meth)acryloyl group and a cationic polymerizable functional group in one molecule.

The present invention aims to provide a photocurable resin composition which rapidly cures by irradiation with active energy rays such as ultraviolet rays and is excellent in adhesion to an electrolyte membrane which is a hard-to-bond material. A photocurable resin composition includes the following ingredients (A) to (C): ingredient (A): a polymer having one or more (meth)acryloyl groups and having a polyisobutylene skeleton containing a [CH.sub.2C(CH.sub.3).sub.2] unit, ingredient (B): a photoradical polymerization initiator, and ingredient (C): a compound having a (meth)acryloyl group and a cationic polymerizable functional group in one molecule.

A vinyl-based comb copolymer includes a polyisobutylene-based macromonomer unit and a vinyl-based monomer unit. A polyisobutylene-based macromonomer has at least 0.8 (meth)acryloyl groups represented by a specific formula at one end of a main chain per molecule, and is copolymerized with a vinyl-based monomer. A method for producing the vinyl-based comb copolymer includes copolymerizing the polyisobutylene-based macromonomer with the vinyl-based monomer. A viscosity index improver includes the comb copolymer. A lubricating oil composition includes the comb copolymer.

A vinyl-based comb copolymer includes a polyisobutylene-based macromonomer unit and a vinyl-based monomer unit. A polyisobutylene-based macromonomer has at least 0.8 (meth)acryloyl groups represented by a specific formula at one end of a main chain per molecule, and is copolymerized with a vinyl-based monomer. A method for producing the vinyl-based comb copolymer includes copolymerizing the polyisobutylene-based macromonomer with the vinyl-based monomer. A viscosity index improver includes the comb copolymer. A lubricating oil composition includes the comb copolymer.

A photocurable gasket resin composition for use in a hard disk drive contains an acryloyl-terminated polyisobutylene, a monofunctional alkyl (meth)acrylate monomer, a polyethylene powder, a phosphate ester, a polyfunctional secondary thiol, a thixotropy-imparting agent, and a photopolymerization initiator. The monofunctional alkyl (meth)acrylate monomer contains a chain skeleton alkyl (meth)acrylate of C8 to C18 and dicyclopentenyl acrylate. The thixotropy-imparting agent contains a compound (f1) derived from castor oil.

A photocurable gasket resin composition for use in a hard disk drive contains an acryloyl-terminated polyisobutylene, a monofunctional alkyl (meth)acrylate monomer, a polyethylene powder, a phosphate ester, a polyfunctional secondary thiol, a thixotropy-imparting agent, and a photopolymerization initiator. The monofunctional alkyl (meth)acrylate monomer contains a chain skeleton alkyl (meth)acrylate of C8 to C18 and dicyclopentenyl acrylate. The thixotropy-imparting agent contains a compound (f1) derived from castor oil.

Provided is a curable composition for a polymer electrolyte, including: a component (A): a radical polymerizable compound having a (meth)acryloyl group, a component (B): a compound having, in one molecule, an epoxy group and a skeleton of at least one selected from the group consisting of polybutadiene, polyisoprene, hydrogenated polybutadiene, and hydrogenated polyisoprene, and a component (C): a radical polymerization initiator, in which a content of each of the components (A) to (C) based on the entire composition is as follows, the component (A): from 30 to 98.9% by mass the component (B): from 1 to 40% by mass, and the component (C): from 0.1 to 15% by mass.

Provided is a curable composition for a polymer electrolyte, including: a component (A): a radical polymerizable compound having a (meth)acryloyl group, a component (B): a compound having, in one molecule, an epoxy group and a skeleton of at least one selected from the group consisting of polybutadiene, polyisoprene, hydrogenated polybutadiene, and hydrogenated polyisoprene, and a component (C): a radical polymerization initiator, in which a content of each of the components (A) to (C) based on the entire composition is as follows, the component (A): from 30 to 98.9% by mass the component (B): from 1 to 40% by mass, and the component (C): from 0.1 to 15% by mass.

A thermoplastic elastomer composition including: a crystalline olefin resin (A) having a melting point of 100 C. or more; an olefin resin (B) satisfying requirements (B-1) to (B-3); and an ethylene/-olefin copolymer (C), the weight ratio of (A)/((B)+(C)) is from 70/30 to 30/70, and the weight ratio of (B)/(C) is from 100/0 to 1/99: (B-1) the resin (B) has a main chain of an ethylene copolymer and a side chain of an ethylene polymer or a propylene polymer, the ethylene copolymer includes repeating units derived from ethylene and repeating units derived from at least one -olefin having 3 to 20 carbon atoms, and the repeating units derived from the -olefin contained within the range of 10 to 50 mol % to the total repeating units in the main chain; (B-2) the melting point measured by DSC rom 60 C. to 170 C.; and (B-3) Tg measured by DSC from 80 C. to 30 C.

A thermoplastic elastomer composition including: a crystalline olefin resin (A) having a melting point of 100 C. or more; an olefin resin (B) satisfying requirements (B-1) to (B-3); and an ethylene/-olefin copolymer (C), the weight ratio of (A)/((B)+(C)) is from 70/30 to 30/70, and the weight ratio of (B)/(C) is from 100/0 to 1/99: (B-1) the resin (B) has a main chain of an ethylene copolymer and a side chain of an ethylene polymer or a propylene polymer, the ethylene copolymer includes repeating units derived from ethylene and repeating units derived from at least one -olefin having 3 to 20 carbon atoms, and the repeating units derived from the -olefin contained within the range of 10 to 50 mol % to the total repeating units in the main chain; (B-2) the melting point measured by DSC rom 60 C. to 170 C.; and (B-3) Tg measured by DSC from 80 C. to 30 C.