Hoechst Aktiengesellschaft

Ernst Wolters

Karlheinz Burg

Gunter Sextro

Heinz Schmidt

Rudolf Kern

Eckart Reske

Werner Schmieder

The invention relates to mixtures composed essentially of polyoxymethylene and of 5 to 60% by weight of a polyurethane, the polyurethane being built up exclusively from aliphatic components and having an elongation at break of 800-1,500% and a Shore hardness A not exceeding 81. The shaped articles produced from the mixture according to the invention are distinguished, above all, by an improved notched impact strength and by matt surfaces.

Toughened polyoxymethylene and shaped articles produced therefrom

The invention relates to mixtures essentially composed of a polyoxymethylene, a polyurethane and a filler, the polyurethane having a Shore hardness A of not more than 90 and the filler having an average particle size less than 10 .mu.m. The shaped articles produced from the mixture according to the invention are distinguished, above all, by improved notched impact strength.

The invention provides a molding composition of a mixture of an oxymethylene polymer, an elastomer having a softening temperature of below the crystallite melting point of the oxymethylene polymer and a second order transition temperature of from -120.degree. to +30.degree. C., and a segmented thermoplastic copolyester. The molding composition of the invention is distinguished by improved mechanical properties, especially with respect to the impact strength.

Thermoplastic molding compositions on the basis of oxymethylene polymers

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.

Oxymethylene copolymer having heat and hydrolysis resistant terminal groups is prepared by heating the polymers present in a liquid phase, whereby a thermal degradation of the unstable terminal groups takes place. The degradation is advantageously effected in the presence of a calcium or magnesium salt of an aliphatic carboxylic acid of low molecular weight. The oxymethylene copolymers are suitable as engineering plastic for preparing semi-finished products and finished products.

Process for preparing a stabilized oxymethylene copolymer

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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Konigstein, Germany

Ernst Wolters