Abstract: Provided is a radical-curable sealing member for fuel cells that has excellent product durability and suppresses changes in mechanical properties caused by heat and hydrolysis (such as reduced stretch and increased hardness caused by embrittlement). A sealing member 4 is a crosslinked product of a radical-curable composition that contains components (A)-(E), there being 0.1-10 parts by mass of component (B) per 100 parts by mass of component (A). (A) A polymer for fuel cell sealing members that has a radical-curable functional group and also has at least one of a urethane linkage and an ester linkage in the molecular chain thereof. (B) A carbodiimide compound that has at least one functional group selected from the group that consists of ether groups, aliphatic hydrocarbon groups that have at least 3 carbons, and alicyclic hydrocarbon groups. (C) A monofunctional (meth)acrylic monomer. (D) A polyfunctional (meth)acrylic monomer. (E) A radical polymerization initiator.

Abstract: A multilayer body that is obtained by bonding a separator, which serves as a base material, and a lip, which serves as a sealing member, to each other by the intermediary of an adhesive layer , wherein: the lip is formed of a rubber composition that contains the component (A) described below; and the adhesive layer is formed of an adhesive that is mainly composed of the component (?) described below. Consequently, this multilayer body exhibits high acid-resistant adhesion at high temperatures, thereby having excellent long-term bonding reliability and excellent sealing properties. (A): A rubber component that is composed of at least one of an ethylene-propylene-diene rubber and an ethylene-butene-diene rubber. (?): A copolymerized oligomer-type silane coupling agent that comprises a specific hydrophilic functional group and a specific hydrophobic functional group at a specific ratio.

Abstract: A member for a fuel cell in which a lip 4b is directly fixed to the surface of a separator 5. In the member for a fuel cell, the lip 4b is a cross-linked body of a radically curable composition containing components (A) to (E) below at a specific ratio, and the glass transition temperature (Tg) of the cross-linked body is ?30° C. or less. (A) (Meth)acrylic polymer having a (meth)acryloyl group at a molecular chain end. (B) Monofunctional (meth)acrylic monomer having a glass transition temperature (Tg) of 0° C. or more and having a polycyclic structure. (C) Monofunctional (meth)acrylic monomer except for component (B). (D) Polyfunctional (meth)acrylic monomer. (E) Radical polymerization initiator.

Abstract: A radical-curable seal member for fuel cell 4 having a glass transition temperature of ?40° C. or lower made from a crosslinked product of a radical-curable composition containing (A) (Meth)acrylic polymer having a (meth)acryloyl group at a molecular chain end, (B) Monofunctional (meth)acrylic monomer, (C) Polyfunctional (meth)acrylic monomer and (D) Radical polymerization initiator, wherein the radical-curable composition contains 20 to 90 weight parts of component (B), 1 to 10 weight parts of component (C), 0.01 to 10 weight parts of component (D) with respect to 100 weight parts of component (A), a weight ratio [(B)/(C)] of the component (B) with respect to the component (C) being 4 to 24, and a content [(C)/{(A)+(B)+(C)}] of the component (C) with respect to a total of 100 wt % of the component (A), the component (B), and the component (C) being 1 to 7 wt %.