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AssigneePolyplastics Co., Ltd.
InventorsTomohiro MONMA, Kazufumi WATANABE, Akihide Shimoda
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A polyoxymethylene resin composition from which formaldehyde is generated in a reduced amount upon molding, without carrying out a stabilization treatment for stabilizing an unstable terminal group in a crude oxymethylene copolymer. A hindered phenol-type antioxidant agent and an ethylene-(methacrylic acid) copolymer resin or an ethylene-(acrylic acid) copolymer resin or a salt thereof are melted and kneaded together to produce a polyoxymethylene resin composition without carrying out a stabilization treatment for stabilizing an unstable terminal group in a crude oxymethylene copolymer for which a polymerization catalyst is deactivated after the completion of copolymerization and in which the unstable terminal group is not yet stabilized. When the polyoxymethylene resin composition is extrusion-molded, the discoloration of a molded product or the deterioration in properties of the molded product can be prevented for a long period of time. The resulting polyoxymethylene resin composition is suitable for forming an extrusion-molded article.
A method of producing a polyoxymethylene resin composition wherein a crude oxymethylene copolymer for which a polymerization catalyst has been deactivated after completing the copolymerization but for which unstable terminal groups have not been stabilized, is melt-kneaded with a hindered phenol-type antioxidant, an ethylene-methacrylic acid copolymer resin or an ethylene-acrylic acid copolymer resin or a salt thereof, and an alkaline earth metal compound, without carrying out a stabilization treatment to stabilize the unstable terminal groups.
Dependencies are inferred from the claim text.