Polyplastics Co., Ltd.

Takeshi Asano

Yukio Ikenaga

Takuzo Kasuga

Masami Yamawaki

Yasuyuki Takeda

Koichi Ichimura

Tsuneyoshi Okada

Hiroshi Nakatsuji

After crude polyacetal polymers mainly comprising bonded oxymethylene groups in the main chain thereof were once molten, they are heated at temperatures of 80.degree. C. or above in liquid mediums, in which said crude polyacetal polymers are insoluble, with keeping a heterogeneous system after they were once molten.

Method of producing polyacetal polymer showing improved heat resistance

The polymer or a copolymer of trioxane copolymer is manufactured by adding 0.001 to 2.0 wt. % of a stereo-hindering phenol to the monomer mixture in advance to the polymerization step and polymerizing trioxane and an optional co-monomer in the presence of a cationic, active catalyst and said phenol.

Method for manufacturing polymer or copolymer of trioxane

A trioxane copolymer is manufactured by adding to trioxane and a co-monomer, 0.0001 to 2.0 percent by weight, based on the total weight of the monomers, of one or more sterically hindered phenols, then co-polymerizing the resultant mixture in the presence of a cation-active catalyst, and then treating the resultant copolymer by heating it at a temperature which is higher than the melting point of the copolymer to melt the copolymer and decompose and remove unstable parts of the copolymer.

Method for manufacturing trioxane copolymer

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Fuji, Japan

Takeshi Asano