Asahi Kasei Kogyo Kabushiki Kaisha

Asahi Kasei Kabushiki Kaisha

Yukio Tanigawa

Noritaka Tanimura

Tadashige Hata

Hirohisa Morishita

Seinosuke Satoh

Sumio Komatsu

Hidehiko Yamatou

Hiromasa Matumoto

A flame-retardant polyacetal resin composition comprising 60 to 90% by weight of a polyacetal resin, 1 to 30% by weight of red phosphorus, 1 to 40% by weight of at least one resin selected from phenol resins and polycarbonate resins, and 0.1 to 5% by weight of a metal salt of a fatty acid. The polyacetal resin composition of the present invention is provided with flame retardancy while maintaining the excellent innate properties of polyacetal resins, so that it can be applied to the fields where the use of polyacetal resins has been restricted.

Flame-retardant polyacetal resin composition

A polyacetal resin composition which comprises about 100 parts by weight of a polyacetal having a residual fluorine concentration of not more than about 13 ppm and a concentration of formaldehyde generated when the polyacetal is heated at about 230&deg; C. for about 30 minutes in nitrogen of not more than about 500 ppm; from about 0.01 to about 3 parts by weight of an antioxidant; and from about 0.001 to about 5 parts by weight of a basic substance. The above polyacetal resin composition is excellent in long-term thermal aging resistance under high-temperature circumstances.

Polyacetal resin composition excellent in aging resistance

A process for producing methylal that involves feeding a liquid containing methanol, formaldehyde and water to an uppermost reactor of at least four solid acid catalyst-filled reactors which are each externally connected to an intermediate portion of a distillation column; and forcibly circulating a liquid containing methanol, formaldehyde, water and produced methylal in a temperature range of 80&deg; C. to 100&deg; C. between the distillation column and each reactor connected to the distillation column below said uppermost reactor, whereby the vapor in the distillation column, which vapor has been subjected to vapor-liquid contact with the liquid containing methanol, formaldehyde, water and produced methylal and which liquid has been subjected to solid-liquid contact in a lowermost reactor of the reactors connected to the intermediate portion of the distillation column, is successively subjected to vapor-liquid contact with the liquids containing methanol, formaldehyde, water and produced methylal circulated between the distillation column and each reactor connected to the distillation column above said lowermost reactor in which the above vapor phase is successively increased.

Process for producing methylal

Process for production of polyoxymethylene

A polyoxymethylene copolymer prepared by copolymerizing a mixture comprising trioxane and 1,3-dioxolane in the presence of at least one polymerization catalyst selected from the group consisting of boron trifluoride, a boron trifluoride hydrate and a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom with boron trifluoride, wherein the 1,3-dioxolane has a 2-methyl-1,3-dioxolane content of not more than 500 ppm by weight and a 1,3-dioxolane peroxide content of not more than 15 ppm by weight in terms of hydrogen peroxide, and contains at least one hindered phenol in an amount of from 10 to 500 ppm by weight, each based on the weight of the 1,3-dioxolane.

Thermally stable polyoxymethylene copolymer

Method for stabilizing unstable terminals of an oxymethylene copolymer

Method for producing a stabilized oxymethylene copolymer

Growing community of inventors

Kurashiki, Japan

Yukio Tanigawa