Extruding three-layer covering for optical fibres etc. - in which one polymer stream is divided into two and extruded into outer layers whilst other polymer is extruded as core layer

摘要

A three-layer covering is extruded to make an optical transmitting element which has at least one light wave conductor. In the process two streams of different materials are fed in to one common extruder die, the first of which is divided into two parts to produce the inner and outer layers, and the other main stream is extruded between those two. The first (subdivided) polymer is pref. polyester, polyester/polyether elastomer, polyolefin, PVC, polyamide, polyetherimide, fluor-polymer, polyetherketone or similar, polysulphone/polysulphide, etc. liquid crystal polymer or polyphenyleneoxide or sulphide, the second (core) polymer is pref. polycarbonate, polyolefin, PVC, polyamide, polyetherimide fluor-polymer, polyetherketone or similar, polysulphone/polysulphide etc. liq. crystal polymer of polyphenyleneoxide/polyphenylenesulphide. ADVANTAGE- Production is simple. Prods. have partic. high mechanical strength and are produced cheaply.