STABILIZED POLYOXYMETHYLENE FORMING COMPOSITION

1419040 Oxymethylene polymer composition HOECHST AG 8 Jan 1974 [12 Jan 1973] 00801/74 Addition to 1321184 Heading C3P An oxymethylene polymer composition is stabilized by (a) 0À05 to 4% of a compound of formula where R 1 is an alkyl radical, R 2 is hydrogen or R 1 , A is a bito hexavalent aliphatic hydrocarbon radical, m is 0 to 6, and n corresponds to the valence of A, (b) 0À01 to 3% of an Mg, Ca, Sr or Ba salt of an aliphatic mono-, di- or tricarboxylic acid having 2 to 9 carbon atoms, or of an araliphatic or aromatic carboxylic acid having from 7 to 9 carbon atoms, and optionally (c) 0À01 to 1% of a compound of formula where R is hydrogen, cyano, hydrocarbyl or hydroxyhydrocarbyl. Other stabilizers may also be included such as amides, polyamides, poly N-vinyl lactams, ureas instead of (c), or light stabilizers, fillers, pigments, dyestuffs or reinforcements. Examples refer to the stabilization of an acetylated formaldehyde homopolymer or a copolymer of trioxan (98%) and ethylene oxide (2%) with (a) tetrakis[beta-(3,5-di-tbutyl - 4 - hydroxyphenyl) - propionyloxymethyl]methane or 1,6 - bis - [beta - (3,5 - dit - butyl - 4 - hydroxyphenyl) - propionyloxy]- hexane, (b) calcium lactate or the magnesium salts of acetic, propionic, caproic, pelargonic, lactic, malic, hydroxy-pivalic, malonic, adipic, salicylic, cinnamic and mandelic acids, and (c) in one case with cyanoguanidine also, and the production of valve discs and plates from the compositions by injection moulding described.