Process of making high-strength yarns

摘要

An ultra-high molecular weight polyolefin having a viscosity average molecular weight of at least 500,000 is subjected to melt forming into a film, the thus obtained molten film or solid state film is transversely stretched while holding both the side edges of the film, the stretched film is longitudinally slitted into tapes, and then the thus obtained tapes are longitudinally stretched thereby to produce high-strength yarns easily. A number of slits are longitudinally or transversely made in films made of an ultra-high molecular weight polyolefin having a viscosity average molecular weight of at least 500,000 so that the films each take a meshy form when spread in the direction perpendicular to the slits, and the meshy form structures are stretched in the direction of the slits to prepare meshy webs having a high strength unidirectionally. At least one member selected from the thus prepared meshy webs is used as one nonwoven web, thereby producing a high-strength, web-crossed laminated nonwoven easily.