Process of making high-strength polyethylene fibers

The present invention relates to high-strength polyethylene fibres which can be used in a wide range of fields, as various ropes, fishing lines, netting and sheeting for engineering, construction and the like, cloth and nonwoven cloth for chemical filters and separators, sportswear and protective clothing such as bulletproof vests, or as reinforcing material for composites for sport, impact-resistant composites and helmets, and particularly as various industrial materials used at from extremely low temperatures to room temperature; where the performance of said fibres, particularly the mechanical properties such as strength and elastic modulus, undergo little variation with temperature during use in environments subject to large changes in temperature; and the present invention relates to a method for producing said fibres sufficiently quickly industrially. The invention relates to high-strength polyethylene fibers of mainly ethylene component having an intrinsic viscosity [ ], when fibrous, of no less than 5, and having a strength of no less than 20 g/d and an elasticity modulus of no less than 500 g/d, and, in the measurement of the temperature variance of the dynamic viscoelasticity of the fibers, the dispersion loss modulus peak temperature is no greater than −110° C. and the loss tangent (tan ) is no greater than 0.03. The invention further relates to a method for producing high-strength polyethylene fibers, wherein a polymerization mixture containing from 99 to 50 parts by weight of (A) and from 1 to 50 parts by weight of (B), where (A) is high molecular weight polymer of mainly ethylene component and having a weight average molecular weight to number average molecular weight ratio (Mw/Mn) of no greater than 4 and an intrinsic viscosity [ ] of no less than 5, and (B) is an ultrahigh molecular weight polymer having an intrinsic viscosity at least 1.2 times that of high molecular weight polymer (A), is dissolved in solvent to a concentration of from 5% by weight to 80% by weight, then spun and drawn.