Hoechst Aktiengesellschaft

Heinz Schmidt

Karlheinz Burg

Gunter Sextro

Ernst Wolters

Rudolf Kern

Thermoplastic molding compositions having improved properties are composed of a mixture of from 99.999 to 90% by weight of a linear polyoxymethylene and from 0.001 to 10% by weight of a branched or cross-linked polyoxymethylene. The linear polyoxymethylenes are homopolymers of formaldehyde or of trioxane or copolymers of trioxane and at least one compound of monofunctional reaction which can be copolymerized with trioxane. The branched or cross-linked polyoxymethylenes are copolymers of trioxane and a multifunctionally reacting compound, or copolymers of trioxane, a monofunctionally reacting compound and a branched or cross-linked polyether. The molding compositions yield shaped articles having improved mechanical properties.

Thermoplastic molding compositions on the basis of polyoxymethylenes

The invention provides thermoplastic molding compositions having improved properties. The compositions are composed of a mixture of from 99.999 to 99.9 wt.% of a linear polyoxymethylene and from 0.001 to 0.1 wt.% of a branched or cross-linked copolymer of trioxan with a multifunctionally reacting compound and optionally a monofunctionally reacting compound, or with a monofunctionally reacting compound and a branched or cross-linked polyether, or of a subsequently branched or cross-linked linear polyoxymethylene having functional groups in lateral or chain position.

Branched or crosslinked poly(exymethylenes) are suitable as nucleating agents for linear poly(oxymethylenes). For ameliorating the mechanical properties of shaped articles, being prepared of such moulding compositions which contain nucleating agents, high molecular weight polymers are used having a certain softening point, second order transition temperature and particle size, and which are blended into the moulding compositions. The modified moulding compositions can be processed in the thermoplastic state and are suitable as industrially useful materials for preparing semi-finished articles and finished products.

Thermoplastic moulding compositions based on poly (oxymethylene)

Oxymethylene polymers are stabilized against the action of heat and oxygen by a stabilizer combination of an ester of a hydroxyl group containing araliphatic or aromatic carboxylic acid and an alkaline earth metal salt of an aliphatic, araliphatic or aromatic carboxylic acid. The efficiency of the stabilizer combination can be further improved by the addition of a costabilizer, especially a guanidine compound. The stabilized poly(oxymethylenes) are suitable for the manufacture of semifinished and finished articles.

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Frankfurt-am-Main, Germany

Heinz Schmidt