The purpose of the present invention is to provide: a polyacetal resin composition which is excellent in terms of impact resistance, thermal stability, and releasability; and a process for producing the polyacetal resin composition. The polyacetal resin composition comprises 100 parts by mass of a polyacetal resin (A) in which the molecular chain has neither a crosslink nor a branch therein, 0.01-10.0 parts by mass of an antioxidant (B), 0.01-5.0 parts by mass of a nitrogenous compound (C), and 0.05-1.0 parts by mass of a fatty acid amide (D), and has a melt index, as measured in accordance with ISO 1133, of 0.5-1.5 g/10 min. A process for producing the polyacetal resin compositions is also provided.

A color concentrate comprising a high molecular weight thermoplastic saturated polyester resin carrier that can be used in the manufacturing of colored clear plastics.

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 resin powder for solid freeform fabrication, having a melting point of 100 degrees C. or higher as measured according to ISO 3146 regulation and a ratio of melt mass-flow rate B to melt mass-flow rate A of greater than 0.80 to 1.20, wherein the melt mass-flow rate A and the melt mass-flow rate B are respectively measured at 15 degrees C. higher than the melting point under a load of 2.16 kg according to JIS K7210 format before and after the resin powder is maintained at a temperature 15 degrees C. lower than the melting point under a pressure of 0.1 kPa for four hours.

A resin powder for solid freeform fabrication, having a melting point of 100 degrees C. or higher as measured according to ISO 3146 regulation and a ratio of melt mass-flow rate B to melt mass-flow rate A of greater than 0.80 to 1.20, wherein the melt mass-flow rate A and the melt mass-flow rate B are respectively measured at 15 degrees C. higher than the melting point under a load of 2.16 kg according to JIS K7210 format before and after the resin powder is maintained at a temperature 15 degrees C. lower than the melting point under a pressure of 0.1 kPa for four hours.

A resin powder for solid freeform fabrication, having a melting point of 100 degrees C. or higher as measured according to ISO 3146 regulation and a ratio of melt mass-flow rate B to melt mass-flow rate A of greater than 0.80 to 1.20, wherein the melt mass-flow rate A and the melt mass-flow rate B are respectively measured at 15 degrees C. higher than the melting point under a load of 2.16 kg according to JIS K7210 format before and after the resin powder is maintained at a temperature 15 degrees C. lower than the melting point under a pressure of 0.1 kPa for four hours.

A polyacetal resin composition includes: in addition to a polyacetal resin as a principal component, 1.5 to 7% by mass of an ethylene-propylene-diene rubber; 0.5 to 3% by mass of a saponified ethylene-vinyl acetate copolymer; and 0.05 to 0.3% by mass of an ethylene--olefin copolymer.

A polyacetal resin composition includes: in addition to a polyacetal resin as a principal component, 1.5 to 7% by mass of an ethylene-propylene-diene rubber; 0.5 to 3% by mass of a saponified ethylene-vinyl acetate copolymer; and 0.05 to 0.3% by mass of an ethylene--olefin copolymer.

A masterbatch of a liquid additive is provided, the resin composition for the masterbatch comprising (a) a block copolymer or a hydrogenated product thereof, the block copolymer containing a polymer block having a vinyl aromatic compound as a main component and a polymer block having a conjugated diene compound as a main component, and 40 to 100 parts by mass of a polyolefinic resin and 100 to 150 parts by mass of an ethylene.-olefin copolymer with respect to 100 parts by mass of the (a) component, wherein the kinematic viscosity at 100 C. is 10 to 5,000 mm.sup.2/s; the ethylene molar content is in the range of 30 to 85 mol %; and the molecular weight distribution (Mw/Mn) for the molecular weight measured by gel permeation chromatography (GPC) with reference to polystyrene is not more than 2.5.