Poly formaldehyde resin composition

Abstract

The present invention relates to a polyoxymethylene composition that is excellent in heat stability and mold properties (mold release and mold cycle) and can be melt and held in a molding machine with the improved prevention of the resin from color change. The present invention provides the polyoxymethylene composition comprising: a polyoxymethylene; (a) 0.01-3.0% by weight (in the composition, hereinafter likewise) of a steric-hindered phenolic antioxidant; (b) 0.01-1.0% by weight of a compound selected from oxides or carboxylic acid salts of an alkali earth metal; and (c) 0.01-1.0% by weight of an ester of a polyhydric alcohol selected from propylene glycol, trimethylol propane and pentaerythritol and a higher fatty acid (C8-C29).

Description

technical field [0001] The present invention relates to a polyoxymethylene resin composition. Background technique [0002] Polyoxymethylene is prepared by polymerization of formaldehyde or its cyclic oligomer trioxane, or by copolymerization of trioxane and comonomers such as cyclic esters and cyclic formals, and its terminal is stabilized Finally, antioxidants and other heat stabilizers are added to prevent decomposition. As antioxidants added to polyoxymethylene, sterically hindered phenolic compounds or sterically hindered amine compounds are disclosed, and as other heat stabilizers, polyamides, urea derivatives, amidine compounds, alkali metals or alkaline earth metals are disclosed. Hydroxide etc. [0003] The acetal resin composition mixed with these, an antioxidant, and a heat stabilizer basically has heat stability and various characteristics, and can be used for ordinary molding processing and the like substantially without any problem. [0004] Therefore, altho...

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Problems solved by technology

[0004] Therefore, although the currently known commercially available polyoxymethylene resin compositions have various properties, they cannot be formed under excessively severe molding conditions, such as melt molding at a relatively high temperature and staying in a molding machine for a long time. In such cases in the cylinder, etc., the polyoxymethylene resin is decomposed under the influence of heat and oxygen in the molding machine cylinder, and the generated formaldehyde deteriorates the working (sanitary) environment. Due to this reaction, the molded product formed of the polyoxymethylene resin Yellow discoloration occurs and economic value is impaired, so it is desired to develop a material that can further improve thermal stability and suppress the discoloration tendency as much as possible