Provided is a rubber composition for producing a rubber molded article that is improved in fouling resistance while being reduced in tackiness and frictional force despite the presence of the rubber in its surface. The rubber composition includes: a rubber A; and a plastic B, in which: the rubber A includes a non-fluorine-based rubber material; a difference in elastic modulus between the rubber A and the plastic B is 50 MPa or more; a sea-island structure having a sea portion containing the rubber A and a plurality of island portions each containing the plastic B is formed; the plastic B is contained at a content of more than 0 vol % and 50 vol % or less with respect to a total amount of the rubber A and the plastic B; and 90% or more of the plurality of island portions each have a volume of 4,000 m.sup.3 or less.

Provided is a rubber composition for producing a rubber molded article that is improved in fouling resistance while being reduced in tackiness and frictional force despite the presence of the rubber in its surface. The rubber composition includes: a rubber A; and a plastic B, in which: the rubber A includes a non-fluorine-based rubber material; a difference in elastic modulus between the rubber A and the plastic B is 50 MPa or more; a sea-island structure having a sea portion containing the rubber A and a plurality of island portions each containing the plastic B is formed; the plastic B is contained at a content of more than 0 vol % and 50 vol % or less with respect to a total amount of the rubber A and the plastic B; and 90% or more of the plurality of island portions each have a volume of 4,000 m.sup.3 or less.

The present invention addresses the problem of providing a polyacetal resin composition which can minimize degradation of a molded product produced from the acetal resin composition, when the molded product is in contact with an acidic cleaner. Said problem is solved by a polyacetal resin composition, comprising: polyacetal copolymer (A) in an amount of 100 parts by mass, wherein said polyacetal copolymer (A) has a hemiformal terminal group content of 0.8 mmol/kg or less; hindered phenol-based antioxidant (B) in an amount of 0.1 to 1.0 part by mass; and at least one selected from an oxide of magnesium or zinc or a hydroxide of magnesium or zinc (C) in an amount more than 2.0 parts by mass and 30 parts by mass or less.

The present invention addresses the problem of providing a polyacetal resin composition which can minimize degradation of a molded product produced from the acetal resin composition, when the molded product is in contact with an acidic cleaner. Said problem is solved by a polyacetal resin composition, comprising: polyacetal copolymer (A) in an amount of 100 parts by mass, wherein said polyacetal copolymer (A) has a hemiformal terminal group content of 0.8 mmol/kg or less; hindered phenol-based antioxidant (B) in an amount of 0.1 to 1.0 part by mass; and at least one selected from an oxide of magnesium or zinc or a hydroxide of magnesium or zinc (C) in an amount more than 2.0 parts by mass and 30 parts by mass or less.

A block copolymer hydrogenate, which is a hydrogenate of a block copolymer having a polymer block (A) containing a structural unit derived from an aromatic vinyl compound in an amount of more than 70 mol %, and a polymer block (B) containing a structural unit derived from a conjugated diene compound in an amount of 30 mol % or more, and further satisfies the following requirements: Requirement (1): The content of the polymer block (A) in the block copolymer hydrogenate is 1 to 30% by mass. Requirement (2): The conjugated diene compound contains isoprene. Requirement (3): A total content of the 1,2-bond unit and the 3,4-bond unit in the structural units derived from the conjugated diene compound is 60 mol % or more. Requirement (4): The hydrogenation rate of the polymer block (B) is 60 mol % or more. Requirement (5): The block copolymer hydrogenate has a serial temperature range where tan , as measured according to JIS K7244-10(2005) and under the conditions of a strain of 0.1%, a frequency of 1 Hz, a measurement temperature of 70 to 100 C. and a rate of temperature increase of 3 C./min, is 1.0 or more, and the maximum width of the temperature range is 16 C. or more.

A block copolymer hydrogenate, which is a hydrogenate of a block copolymer having a polymer block (A) containing a structural unit derived from an aromatic vinyl compound in an amount of more than 70 mol %, and a polymer block (B) containing a structural unit derived from a conjugated diene compound in an amount of 30 mol % or more, and further satisfies the following requirements: Requirement (1): The content of the polymer block (A) in the block copolymer hydrogenate is 1 to 30% by mass. Requirement (2): The conjugated diene compound contains isoprene. Requirement (3): A total content of the 1,2-bond unit and the 3,4-bond unit in the structural units derived from the conjugated diene compound is 60 mol % or more. Requirement (4): The hydrogenation rate of the polymer block (B) is 60 mol % or more. Requirement (5): The block copolymer hydrogenate has a serial temperature range where tan , as measured according to JIS K7244-10(2005) and under the conditions of a strain of 0.1%, a frequency of 1 Hz, a measurement temperature of 70 to 100 C. and a rate of temperature increase of 3 C./min, is 1.0 or more, and the maximum width of the temperature range is 16 C. or more.

A polyacetal resin composition and a molded product thereof are provided which are excellent in thermal stability, little elution of components of the resin composition upon brought into contact with fuel, and good releasability from the mold at the time of molding, and which is excellent in the points of thermal stability, fuel oil resistance and mold releasability. Provided is a polyacetal resin composition which includes (A) a polyacetal resin and (B) a mold release agent, (B) the mold release agent is a polyolefin-based wax and/or a polytetrafluoroethylene-based wax, and a content of (B) the mold release agent in the polyacetal resin composition is 0.01 part by mass or more and 1.0 part by mass or less based on 100 parts by mass of (A) the polyacetal resin.

A polyacetal resin composition and a molded product thereof are provided which are excellent in thermal stability, little elution of components of the resin composition upon brought into contact with fuel, and good releasability from the mold at the time of molding, and which is excellent in the points of thermal stability, fuel oil resistance and mold releasability. Provided is a polyacetal resin composition which includes (A) a polyacetal resin and (B) a mold release agent, (B) the mold release agent is a polyolefin-based wax and/or a polytetrafluoroethylene-based wax, and a content of (B) the mold release agent in the polyacetal resin composition is 0.01 part by mass or more and 1.0 part by mass or less based on 100 parts by mass of (A) the polyacetal resin.

A quaternary ammonium compound represented by the following formula (1):
[(R1).sub.m(R2).sub.4-mN.sup.+].sub.nX.sup.n(1) wherein each R1 independently represents an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; an aralkyl group where an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms is substituted with at least one aryl group having 6 to 20 carbon atoms; or an alkylaryl group where an aryl group having 6 to 20 carbon atoms is substituted with at least one unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; each R2 independently represents a group having 2 to 60 carbon atoms and 2 to 30 oxygen atoms, the group represented by the following formula: (RO)k-H, wherein R represents a substituted or unsubstituted alkyl group and k represents a natural number of 2 or more.

A quaternary ammonium compound represented by the following formula (1):
[(R1).sub.m(R2).sub.4-mN.sup.+].sub.nX.sup.n(1) wherein each R1 independently represents an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; an aralkyl group where an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms is substituted with at least one aryl group having 6 to 20 carbon atoms; or an alkylaryl group where an aryl group having 6 to 20 carbon atoms is substituted with at least one unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; each R2 independently represents a group having 2 to 60 carbon atoms and 2 to 30 oxygen atoms, the group represented by the following formula: (RO)k-H, wherein R represents a substituted or unsubstituted alkyl group and k represents a natural number of 2 or more.