Abstract: A composition obtained by adding at least one specific elastomer and optionally a polyamide resin or a bromine-containing flame retardant to a melt-kneaded product of a polyphenylene sulfide with a non-blocked type polyfunctional isocyanate compound. The composition is excellent not only in impact resistance but also in aging resistance at high temperatures. Said composition can be advantageously used for molding parts of automobile engines, parts for various machines, connectors for electric or electronic parts, bobbines and the like.

Abstract: A process for formaldehyde production is disclosed comprising the steps of reacting methanol with formaldehyde to form methylal and then oxidizing the resulting methylal to obtain formaldehyde. Formaldehyde derivatives may also be produced. A dilute formaldehyde solution resulting from recovery of the product is recycled and used as feed material for the initial reaction step.

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.

Abstract: A method for synthesizing trioxane by heating and reacting an aqueous formaldehyde solution in the presence of a heteropolyacid. As the heteropolyacid, there is preferably used one that contains, as a coordinating element or coordinating elements, W, Mo, V or Nb alone or two or more of them.

Abstract: A process for recovering trioxane from an aqueous solution containing trioxane and triethylamine by the distillation separation process which comprises feeding an aqueous solution containing trioxane and triethylamine to the first distillation column, distilling out triethylamine, trioxane and water from the column top of the first distillation column, withdrawing an aqueous solution containing the major part of the trioxane present in the fed solution from the column bottom of the first distillation column, feeding the withdrawn solution to the second distillation column and taking out the substantially whole quantity of the trioxane fed to the second distillation column from the column top of the second distillation column.

Abstract: An oxymethylene copolymer produced from trioxane, a cyclic ether and/or a cyclic formal in the presence of a cationic polymerization catalyst is contacted with a deactivating agent for the catalyst in the state of gas phase at a temperature of 160.degree. C. or lower to deactivate the cationic polymerization catalyst rapidly and completely without causing degradation of the copolymer produced.

Abstract: A polyoxymethylene composition comprising (a) 100 parts by weight of polyoxymethylene, (b) 2 to 15 parts by weight of electrically conductive carbon black, and (c) 2 to 20 parts by weight of low-density polyethylene has excellent antistatic properties. Shaped articles produced by the polyoxymethylene composition show excellent effects on preventing noise due to static electricity and adhesion of dust.

Abstract: A method for synthesizing trioxane by heating and reacting an aqueous formaldehyde solution in the presence of a heteropolyacid. As the heteropolyacid, there is preferably used one that contains, as a coordinating element or coordinating elements, W, Mo, V or Nb alone or two or more of them.

Abstract: In a process for separating trioxane by a continuous distillation which comprises extracting, with benzene, the trioxane-containing distillate obtainable by heating an aqueous solution of formaldehyde, feeding the trioxane-containing benzene solution into a distillation column as a starting material, distilling out the benzene from the column top and withdrawing the trioxane from the column bottom, a process for separating trioxane which comprises retaining the concentration of trioxane X in the liquid composition at the starting material feeding plate of the distillation column (% by weight of trioxane based on the total liquid composition at the feeding plate) in the range satisfying the following relationship: ##EQU1## wherein R is reflux ratio, and .gamma. is a parameter defined by the following equation: ##EQU2## wherein q is the proportion of liquid part in the fed starting material as expressed in terms of ratio by weight and C (%) is the concentration of trioxane in the fed starting material.

Abstract: Stabilized polyoxymethylene excellent in heat stability, base stability and mechanical properties can be produced by reacting polyoxymethylene having a number average molecular weight of 10,000 or more with 1,3-dioxepane in an organic medium in the presence of a Lewis acid and, if necessary, a molecular weight regulator.