Process for producing stretched articles of ultrahigh-molecular-weight polyethylene

A process for producing a stretched article of ultrahigh-molecular-weight polyethylene, which comprises

• (1) melt-kneading a mixture composed of (A) 15 to 80 parts by weight, per 100 parts by weight of the components (A) and (B) combined, of ultrahigh-molecular-weight polyethylene having an inherent viscosity [.eta.], determined at 135.degree. C. in decalin, of at least 5 dl/g and (B) 85 to 20 parts by weight, per 100 parts by weight of the components (A) and (B) combined, of a paraffinic wax having a melting point, determined by the DSC method, of 40.degree. to 120.degree. C. and a weight average molecular weight (Mw), determined by the GPC method, of at least 230 but less than 2,000 in a screw extruder while maintaining the temperature of the mixture at 180 to 280.degree. C.,
• (2) melt-extruding the molten mixture through a die kept at a temperature of 180.degree. to 300.degree. C., under a draft condition at a draft ratio of not less than 2,
• (3) cooling the resulting unstretched extrudate to solidify it, and
• (4) subjecting the unstretched solidified extrudate to a stretching treatment at a temperature of 60.degree. to 140.degree. C. at a stretch ratio of at least about 3:1.