Abstract: 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° 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.

Abstract: At least one aliphatic carboxylic acid metal salt is added to a terminally-stabilized polyacetal resin, said salt having occluded therein at least one metal compound selected from the group consisting of a metal hydroxide and a metal chloride, and optionally having attached to a surface thereof at least one metal compound selected from the group consisting of a metal hydroxide and a metal chloride.

Abstract: The present invention provides an acetal resin composition comprising:(A) 100 parts by weight of oxymethylene copolymers;(B) 0.05 to 2 parts by weight of hindered phenol type antioxidants; and(C) 0.002 to 0.3 parts by weight of ion adsorbents selected from the group consisting of (i) an ion adsorbent comprising (a) one or more oxides selected from the alkaline metal oxides and the alkaline earth metal oxides and (b) one or more trivalent metallic oxides, and (ii) an ion adsorbent represented by the general formula:M.sub.1 1-X M.sub.2X (OH).sub.2 A.sup.n-.sub.x/n.mH.sub.2 O(1)wherein M.sub.1 is one or more bivalent alkaline earth metal atoms, M.sub.2 is a trivalent metal, A.sup.n- is an anion of valence n, 0<X.ltoreq.0.5, and m is a positive number.

Abstract: Disclosed are an acetal copolymer composed of polyacetal units and particulate crosslinked polymer units which has a viscosity of 0.1-10 dl/g and comprises a polyacetal and a particulate crosslinked polymer other than a polyacetal which has a functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, an amide group, an alkoxy group, an acid anhydride group, and an epoxy group and has an average particle size of 0.01-10 .mu.m, said polyacetal and particulate crosslinked polymer being reaction bonded to each other through the functional group and a process for producing an acetal copolymer composed of polyacetal units and polymer units other than polyacetals which comprises a polyacetal and a polymer other than a polyacetal which are reaction bonded to each other through a functional group mentioned below and which has a viscosity of 0.

Abstract: The present invention relates to a polyacetal copolymer comprising a polyoxymethylene group (A) and a vinyl polymer group (B), the copolymer having a structure of the formula (I):A.sub.n --X--B (I)wherein X is a terminal group of B and represents a binding group derived from a compound having at least two carbon atoms and 1 to 4 groups selected from hydroxyl, carboxyl, ester, amino and alkoxy groups, and A.sub.n means that A is present in the quantity of n times in number, and bonds to X, in which n=1 to 4, and the copolymers has a number average molecular weight of 10,000 to 500,000; a process for the production of said copolymer; and a composition comprising said copolymer and a polyvinyl polymer and/or polyoxymethylene.

Abstract: A thermoplastic resin is formed by imparting thermoplasticity to monosaccharide and/or polysaccharide units to form engineering resin that has excellent mechanical property attributes and excellent biodegradability. A thermoplastic graft copolymer is formed by graft-polymerizing graft to backbone. The copolymer comprises backbone which constitutes the monosaccharide and/or polysaccharide units each having a functional group selected from the group consisting of the hydroxyl group, carboxyl group, amino group and amido group, and graft constituting the polyacetal units consisting of repetitive oxymethylene units --CH.sub.2 O-- that are reaction-bonded with each other through the functional group, the polyacetal units being graft-polymerized to the monosaccharide and/or polysaccharide units. The copolymer has viscosity of 0.1-10 (dl/g) and a melting point of 150.degree.-175.degree. C.

Abstract: A process for producing formaldehyde having high purity is disclosed, which comprises: (A) feeding crude formaldehyde containing water and methanol to the middle or lower part of a distillation column, and feeding a polyalkylene oxide compound which is inert to formaldehyde to the upper part of the column in an amount at least 10 times the total weight of the water and methanol contained in the crude formaldehyde; (B) carrying out distillation; and (C) recovering purified formaldehyde gas from the top of the column while withdrawing a solution containing the polyalkylene oxide compound, water and methanol from the bottom of the column. Using this process, formaldehyde having stable high purity can be obtained continuously through simplified steps at low cost.