A photocurable composition is provided. A cured product formed by curing the photocurable composition has reworkability and excellent heat resistance while having flexibility. The photocurable composition includes a telechelic acrylic polymer having an acryloyl group at both ends; a polyfunctional acrylic polymer having acryloyl groups; a monofunctional acrylic monomer; and a fumed silica including at least one of a hydrophilic fumed silica or a fumed silica having a polar group. The photocurable composition has a Martens hardness of 0.07 to 0.75 N/mm.sup.2, where the Martens hardness is a hardness after the photocurable composition is cured.

To provide a statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit which has a satisfactory oil resistance. A method for producing a statistical copolymer containing a chloroprene monomer unit and an unsaturated nitrile monomer unit includes a step for conducting continuous addition or 10 cycles or more of intermittent portionwise addition of the chloroprene monomer after initiation of a polymerization reaction is provided. A rubber composition using a statistical copolymer according to the invention or a vulcanized molded article containing the rubber composition is excellent in terms of oil resistance, mechanical strength, compression set at a low temperature and flex fatigue resistance.

To provide a shaft seal that is capable of decreasing rotational torque and realizing superior sealing performance. A shaft seal 1 having a ring shape adheres to an outer peripheral surface of a rotational shaft 6 and thereby seals sealed fluid. The shaft seal 1 partitions a gap between the rotational shaft 6 and a housing 7 to which the shaft seal 1 is mounted, into a high-pressure side and a low-pressure side. The shaft seal 1 is an injection-molded body having a generally U-shape in a sectional view about an axial direction. The shaft seal 1 has a seal lip part 2 that is configured to extend to the high-pressure side and slide on the rotational shaft 6, and an outer lip part 3 that is disposed at an outer diametrical side relative to the seal lip part 2. An inclined angle α of the seal lip part 2 relative to the outer peripheral surface of the rotational shaft 6 is 5-20 degrees. The length L.sub.2 of the seal lip part 2 in the sectional view about the axial direction of the shaft seal 1 is 2.0-6.5 mm.

A rubber composition is provided that contains an ethylene-butene-diene terpolymer, silica having a CTAB specific surface area of 30 m.sup.2/g or more and 150 m.sup.2/g or less, a silane coupling agent, and a crosslinking agent, in which a content of the silica per 100 parts by weight of the ethylene-butene-diene terpolymer is 25 parts by weight or more and 90 parts by weight or less.

Provided is a sealant composition that makes it possible to suppress a flow of a sealant associated with travel while maintaining good sealing properties. As a sealant composition constituting a sealant layer (10) disposed on the inner surface of a pneumatic tire, the following are used: a sealant composition demonstrating a tensile stress at 20% elongation at 23° C. of 0.03 MPa or less and a tensile stress at 20% elongation at 80° C. of 0.002 MPa; or a sealant composition demonstrating a viscosity V.sub.0 at 0° C. of from 2 kPa.Math.s to 15 kPa s, a viscosity V.sub.40 at 40° C. of from 1 kPa s to 14 kPa s, and a viscosity V.sub.80 at 80° C. of from 0.5 kPa.Math.s to 12 kPa.Math.s.

This invention reveals an uncured pneumatic tire which is comprised of a generally toroidal-shaped supporting carcass with an outer circumferential tread, two spaced beads, at least one ply extending from bead to bead, sidewalls extending radially from and connecting said tread to said beads, a sealant layer which is disposed inwardly from the supporting carcass, and an innerliner which is disposed inwardly from the sealant layer, wherein said circumferential tread is adapted to be ground-contacting, and wherein the sealant layer is comprised of polyisobutylene or a butyl rubber, wherein the polyisobutylene or the butyl rubber has a number average molecular weight which is within the range of 30,000 to 100,000.

An acrylic rubber includes 20 to 35% by weight of ethyl methacrylate units (a), 0 to 20% by weight of ethyl acrylate units (b), 50 to 75% by weight of n-butyl acrylate units (c), and 0.5 to 4% by weight of carboxyl group-containing monomer units (d).

An electrolytic capacitor includes a capacitor element, a case, and a sealing member. The case has an opening and houses the capacitor element. The sealing member seals the opening. The sealing member includes an elastic member that is fit in the opening. The elastic member includes a polymer component and a particle component. The polymer component includes at least butyl rubber. The particle component includes at least particles of kaolin. An average particle size of the particles of kaolin is less than or equal to 4 μm.

An aspect of the present invention is an acrylic rubber containing an alkyl acrylate, an alkyl methacrylate and ethylene as monomer units, wherein a content of a polyvinyl alcohol in the acrylic rubber is 0.5 to 2% by mass.

An aspect of the present invention is an acrylic rubber containing an alkyl acrylate, ethylene and vinyl acetate as monomer units, wherein a content of a polyvinyl alcohol in the acrylic rubber is 0.5 to 2% by mass.