Abstract: A laminating blow molding method for making a hollow article includes steps of: laminating a resin sheet on an outer surface of a parison extruded from a path between a die head and a core; sandwiching the parison with the resin sheet between a pair of mold pieces constituting a mold while heating the mold to a temperature exceeding softening temperatures of the resin sheet and the parison, one of the mold pieces having shifting members at side portions thereof; closing the mold so that the parison with the resin sheet is held inside the mold, and moving the shifting members to the other of the mold pieces so that overhangs at both ends of the parison and resin sheet are pressed rearwardly to shift rearwardly burrs which are pressed out from the mold; and blowing the parison to perform blow molding. Thereafter, the mold is cooled and the molded article is taken out. In the method, a front side of the molded article is formed smoothly.

Abstract: Undesirable deposition of polyoxymethylene onto the inner wall of a polymerization vessel and onto a stirrer, which deposition is observed in the slurry polymerization of formaldehyde carried out in an inert organic liquid medium in the presence of a polymerization catalyst, can be minimized by carrying out the slurry polymerization in the presence of at least one polyvalent metal salt selected from polyvalent metal salts of alkylsalicylic acids and polyvalent metal salts of dialkyl esters of sulfosuccinic acid. Optionally, a polyethylene glycol monoether may be used in addition to the polyvalent metal salt.

Abstract: A method of stabilizing oxymethylene copolymers which comprises heating an oxymethylene copolymer in a hydrocarbonaceous mixed medium consisting of about 50 - 92% by weight of a hydrocarbon having 5 - 7 carbon atoms, about 6 - 48% by weight of an alcohol and about 2 - 20% by weight of water based on the total amount of the medium, at a temperature of from about 100.degree. to about 170.degree. C. in the presence of a salt selected from the group consisting of the sodium and potassium salts of ethylenediaminetetraacetic acid under the conditions of a pH value of from about 4 to about 7.