GB1026771A - Polyacetal compositions - Google Patents

Abstract

A linear polyacetal is compounded with a stabilizer comprising at least one phenolic compound compatible therewith which is either a spirohydrindene obtainable by the condensation of three mols. of a ketone, viz. RCH2COCH2R1, where R and R1 are hydrocarbon groups or hydrogen, with two mols. of a phenol having a meta and para position free and preferably having an ortho substituent or else has the formula <FORM:1026771/C3/1> where R1 or R3 and R6 or R8 are -OH and the remaining substituents are as R above or alkoxyl, there being at least one hydrocarbon group ortho or para to each -OH and R11 and R12 are alkyl, hydroxy aryl which may be substituted by hydrocarbon or oxacycloalkyl, cycloalkyl or hydrogen, at least one being a hydroxy aryl group. The polyacetal may be polyoxymethylene and may be formed by copolymerization of an aldehyde or polymer there-of, e.g. trioxane, with a minor molar proportion, e.g. 15 mole per cent, of a cyclic ether, oxide, e.g. ethylene oxide, acetal, carbonate or lactone. The composition may also contain as stabilizer para - amino - acetanilide, a cyanoguanidine, 2 - mercaptobenzimidazole, a polycondensate of an alkylene glycol and a thiodialkanoic acid or of hexamethylene diisocyanate and polythiodiglycol or of hexamethylene diamine and thiodipropionic acid, N,N1-dilauryl b ,b 1-thiodipropionamide, a zinc dialkyl dithiophosphate, dihexadecylthioether.