The present invention relates to a thermally expandable fire resistant material comprising at least one matrix resin selected from the group consisting of a thermoplastic resin and a rubber and a thermally expandable graphite, having an expansion pressure of 3.0 N/cm.sup.2 or more. According to the present invention, a fire resistant material capable of exhibiting excellent fire resistance can be provided.

A sulfur-modified chloroprene rubber having a functional group A represented by specific General Formula (A) and positioned at a molecular terminal and a functional group B represented by specific General Formula (B) and positioned at a molecular terminal, in which a mass ratio B/A of a content of the functional group B with respect to a content of the functional group A is more than 0 and 6.00 or less, and a total amount of the functional group A and the functional group B is 0.10 to 0.60% by mass.

A sulfur-modified chloroprene rubber having a functional group A represented by specific General Formula (A) and positioned at a molecular terminal and a functional group B represented by specific General Formula (B) and positioned at a molecular terminal, in which a mass ratio B/A of a content of the functional group B with respect to a content of the functional group A is more than 0 and 6.00 or less, and a total amount of the functional group A and the functional group B is 0.10 to 0.60% by mass.

A rubber composition from which a vulcanized rubber simultaneously improved in three characteristics of oil resistance, cold resistance and ozone resistance can be obtained, and a molded article using the vulcanized rubber are provided. The rubber composition contains 50 to 99 parts by mass of a chloroprene rubber containing 0.01 to 20% by mass of an unsaturated nitrile monomer unit and 1 to 50 parts by mass of a non-conjugated diene rubber.

A rubber composition from which a vulcanized rubber simultaneously improved in three characteristics of oil resistance, cold resistance and ozone resistance can be obtained, and a molded article using the vulcanized rubber are provided. The rubber composition contains 50 to 99 parts by mass of a chloroprene rubber containing 0.01 to 20% by mass of an unsaturated nitrile monomer unit and 1 to 50 parts by mass of a non-conjugated diene rubber.

A vibrationproof rubber composition capable of obtaining a vibrationproof rubber having a specific hardness and an excellent balance of mechanical properties, vibrationproof properties, and a friction coefficient, a vulcanized molded body obtained by vulcanizing the vibrationproof rubber composition, and vibrationproof rubber is provided. A vibrationproof rubber composition comprising: 100 parts by mass of xanthogen-modified chloroprene rubber; 0.5 to 2 parts by mass of stearic acid amide; and 4 to 5 parts by mass of erucic acid amide, wherein: the vibrationproof rubber composition further comprises carbon black with an average primary particle diameter of 60 to 470 nm, and a molded body obtained by vulcanizing the vibrationproof rubber composition has a type A durometer hardness of 50 to 70 is provided.

A vibrationproof rubber composition capable of obtaining a vibrationproof rubber having a specific hardness and an excellent balance of mechanical properties, vibrationproof properties, and a friction coefficient, a vulcanized molded body obtained by vulcanizing the vibrationproof rubber composition, and vibrationproof rubber is provided. A vibrationproof rubber composition comprising: 100 parts by mass of xanthogen-modified chloroprene rubber; 0.5 to 2 parts by mass of stearic acid amide; and 4 to 5 parts by mass of erucic acid amide, wherein: the vibrationproof rubber composition further comprises carbon black with an average primary particle diameter of 60 to 470 nm, and a molded body obtained by vulcanizing the vibrationproof rubber composition has a type A durometer hardness of 50 to 70 is provided.

A power transmission belt includes a pulley non-contacting portion made of a rubber composition. The rubber composition contains a rubber component, cellulose-based fine fibers, and a non-carbon black hydrophilic inorganic filler, and contains no carbon black or contains carbon black in an amount of less than 20 parts by mass relative to 100 parts by mass of the rubber component.

A power transmission belt includes a pulley non-contacting portion made of a rubber composition. The rubber composition contains a rubber component, cellulose-based fine fibers, and a non-carbon black hydrophilic inorganic filler, and contains no carbon black or contains carbon black in an amount of less than 20 parts by mass relative to 100 parts by mass of the rubber component.

The present invention pertains to a frictional power transmission belt including a tension member extending in the longitudinal direction of the belt and an adhesion rubber layer in contact with at least a portion of the tension member, in which the adhesion rubber layer is formed of a vulcanized rubber composition containing a rubber component, short fibers having an average fiber diameter of 2 μm or more, and a filler.