Block-type aryl copolyesters and filaments based on these copolyesters

Abstract

Disclosed are block-type aryl copolyesters, the process for obtaining these as well as the filaments produced therefrom, and the process for obtaining such filaments. The aryl copolyesters contain from 10 to 90% of recurring flexible units of the formula ##STR1## WHERE R is an aliphatic, alicyclic or araliphatic radical, x is an integer from 2 to 6, and y = 0 or 1, and From 90 to 10% of recurring rigid units of the formula ##STR2## and have an inherent viscosity of at least 0.25. The raw spun filaments produced therefrom possess a modulus of elasticity of at least 1,000 g/tex, and preferably at least 1,500 g/tex, and are obtained by melt-spinning at a temperature such that the copolyester is optically anisotropic at rest and in the relaxed state, followed by winding up the filament in a per se known manner. Such filaments can be used advantageously as reinforcing filaments.

Dependencies are inferred from the claim text.