Low-halogen-content, thermoplastic polyurethane elastomer having improved flame resistance by the addition of a 4-component additive combination, its production and its use

A thermoplastic polyurethane elastomer containing flameproofing agents and fillers and having improved flameproof, electrical surface and abrasion properties, comprising

• (A) from 97.5 to 76% by weight of a thermoplastic polyurethane optionally containing light stabilizers, oxidation inhibitors and UV-absorbers, from 2.5 to 24% by weight of additive components (B) to (F) in quantitative proportions of
• (B) from 1to 10% by weight of antimony trioxide,
• (C) from 0.3 to 6% by weight of chlorinated and/or brominated compounds having a halogen content of from 50 to 88% by weight,
• (D) from 1 to 8% by weight of aluminum hydroxide having a particle size of from 0.1 to 100.mu.,
• (E) from 0.2 to 4% by weight of phosphoric acid tris-ester and, optionally,
• (F) up to 5% by weight of quaternary tetra-alkyl ammonium salts.

In a process of extrusion comprising extruding a thermoplastic, the improvement, wherein the thermoplastic is a polyurethane elastomer having improved flame resistance, electrical surface properties and abrasion resistance by the addition of flameproofing agents and fillers, characterized in that

• (A) from 2.5 to 24% by weight of a combination of additives are incorporated into a thermoplastic polyurethane elastomer, said additives being present in amounts of
• (B) from 1 to 10% by weght of antimony trioxide,
• (C) from 0.3 to 6% by weight of chlorinated or brominated compounds having a halogen content of from 50 to 88% by weight,
• (D) from 1 to 8% by weight of aluminium hydroxide having a particle size of from 0.1 to 100.mu.,
• (E) from 0.2 to 4% by weight of phosphoric acid tris-ester and
• (F) up to 5% by weight of quaternary tetra-alkyl ammonium salts,
• all of said percents being based on the total weight of the elastomer and additives, are added to the thermoplastic polyurethane elastomer before, during or after the polyurethane-forming reaction and wherein the extrusion temperature of the thermoplastic is kept at temperatures .ltoreq.200.degree. C.