High strength core-sheath monofilaments for technical applications

Monofilaments with a core-sheath structure comprising a core of a thermoplastic polyester or copolyester, wherein the polyester or copolyester of the core has a melting point of 200.degree. to 300.degree. C., and includes at least 70 mol %, based on the totality of all polyester structural units, of structural units derived from aromatic dicarboxylic acids and from aliphatic diols, and not more than 30 mol %, based on the totality of all polyester structural units, of dicarboxylic acid units which differ from the aromatic dicarboxylic acid units which form the predominant portion of the dicarboxylic acid units or are derived from araliphatic dicarboxylic acids having one or more fused or unfused aromatic nuclei, or from cyclic or acyclic aliphatic dicarboxylic acids having in total 4 to 12 carbon atoms, and diol units derived from aliphatic diols and which differ from the diol units which form the predominant portion of the diol units, or which are derived from branched or longer-chain diols having 3 to 10 carbon atoms, or from cyclic diols, or from diols which contain ether groups, or from polyglycol having a molecular weight of about 500-2000, and a sheath comprising a polyester mixture including a thermoplastic polyester whose melting point is between 200.degree. and 300.degree. C., and a thermoplastic, elastomeric copolyether-ester which contains 40-60% by weight of longer-chain polyether diols having an average molecular weight of 600-4,000 as soft segments and which in filament form has a breaking strength of 0.8 to 6.5 cN/tex, and a breaking extension of 300 to 1200%.