A gasket includes an elastic part containing a rubber having a dynamic spring constant of 1.5 g/μm or lower as measured under conditions of 23±2° C., 100 Hz, and a strain amplitude of 0.1% according to JIS K6394:2007.

Provided are a resin composition for sealing an optical semiconductor providing both UV transmission and heat resistance, and a molded resin product for sealing an optical semiconductor, an optical semiconductor-sealing material, and an optical semiconductor device each including the same. The resin composition satisfies the relationship X=(A1×A2)/A3+(B1×B2)/B3+ . . . <0.0005 wherein A1 represents the mass ratio of an aromatic compound, A2 represents the number of aromatic rings per molecule of the aromatic compound, A3 represents the molecular weight of the aromatic compound, and A, B, . . . each represent an aromatic compound. The composition contains an epoxy, an alicyclic acid anhydride, and an antioxidant. When formed into a cured product (size: 50 mm in width×50 mm in length×1 mm in thickness), a linear transmittance at 300 nm is 80% or higher and a linear transmittance at 400 nm is 95% or higher.

Provided are a novel acrylic polymer that has moderate crosslinking reactivity and is suitable for sealant applications and a sealant using the polymer. The (meth)acrylic acid alkyl ester polymer according to the invention has a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) method of 30,000 to 150,000 and a number average molecular weight (Mn) of less than 20,000 and has 1.1 to 3.0 methyldimethoxysilyl groups, more than 0.5 methyldimethoxysilyl groups at side chains of a molecular chain, and more than 0.5 methyldimethoxysilyl groups at molecular chain terminals, per one molecule of the polymer.

Provided is a sealant material composition that makes it possible to ensure good sealing properties and to suppress sealant flow due to traveling. As a sealant material composition forming a sealant layer disposed on an inner surface of a pneumatic tire, a sealant material composition comprising from 1 part by mass to 40 parts by mass of an organic peroxide and from 0.1 parts by mass to 40 parts by mass of a crosslinking agent, being blended, per 100 parts by mass of a rubber component containing a chlorinated butyl rubber, is used.

A seal rubber composition contains a carboxyl group-containing acrylic rubber, silica, and two or more inorganic fibers, an amount of the silica per 100 parts by weight of the carboxyl group-containing acrylic rubber is 25 to 100 parts by weight, and a total amount of the inorganic fibers per 100 parts by weight of the carboxyl group-containing acrylic rubber is 35 to 100 parts by weight. A sealing member includes a sliding portion composed of a vulcanized product of the seal rubber composition.

The present disclosure provides a high-pressure hydrogen apparatus gas seal member which is excellent in durability and is capable of sufficiently suppressing an occurrence of a blister fracture. A high-pressure hydrogen apparatus gas seal member of the present disclosure is a high-pressure hydrogen apparatus gas seal member made of a crosslinked product of an elastomer composition which comprises an elastomer and fibrous carbon nanostructures having an average length of 100 μm or more and 1000 μm or less, wherein the fibrous carbon nanostructures have a surface fractal dimension of 2.3 or more and 3.0 or less or a radius of gyration of 50 nm or more and 500 nm or less, and further the fibrous carbon nanostructures has an inner diameter of 4.0 nm or less.

A vessel closure (1, 21, 41, 61) includes a sealing element (3, 23, 43, 63). The sealing element (3, 23, 43, 63) includes a polymer composition. The polymer composition includes a polyalphaolefin with kinematic viscosity, determined according to ASTM D445 / ISO 3104, of at least 4 cSt, at a temperature of 100° C., and/or a dropping point, determined according to ASTM 5950, of at most -10° C., and up to 95% by weight of a second polyolefin.

An acrylic rubber composition includes an acrylic rubber and a specific antioxidant, wherein the acrylic rubber includes 15 to 55% by weight of methacrylic acid alkyl ester monomer units (a), 44.5 to 84.5% by weight of acrylic acid ester monomer units (b), and 0.5 to 4% by weight of carboxyl group-containing monomer units (c), and the content of the antioxidant is 0.1 to 5 parts by weight relative to 100 parts by weight of the acrylic rubber.

Disclosed is a gas seal member for high-pressure hydrogen device with sufficiently reduced occurrence of both swelling destruction and blister destruction. The gas seal member is formed of a cross-linked product of an elastomer composition which comprises an elastomer and fibrous carbon nanostructures, wherein a hydrogen diffusion coefficient D1 of a cross-linked product of an elastomer component including the elastomer and a hydrogen diffusion coefficient D2 of the cross-linked product of the elastomer composition satisfy the relationship 0.7<D2/D1<1.0.

An object of the present invention is to provide an epoxy amine adduct, a curing catalyst, a resin composition, a sealing material, an adhesive agent, and a cured product, which have good characteristics. There is prepared an epoxy amine adduct in which a value of (melting onset temperature at a temperature increasing rate of 50° C./min)/(melting onset temperature at a temperature increasing rate of 10° C./min) in differential scanning calorimetry (DSC) is 1.00 or more and 1.10 or less. There are prepared a curing catalyst for epoxy resin containing the epoxy amine adduct, a resin composition containing the curing catalyst, a sealing material or an adhesive agent each containing the resin composition, and a cured product obtained by curing the resin composition.