Cable sheathing with vinyl chloride polymers - by applying paste contg. non-crosslinked PVC with high K-value, or crosslinked PVC, and gelling at 80-250 deg. C

摘要

Prodn. of cable sheathing (I) based on vinyl chloride polymer (II) with K value 60-100 contg. 50-100 wt. % vinyl chloride (VC) 0-50 wt. % other ethylenic comonomers with a single double bond (III) and 0-20 wt. % poly-unsatd. (IV) or functional (V) comonomers by prepg. (II) as a paste by addn. of 30-80 wt. % plasticiser (w.r.t. amt. of (II) in the paste) and opt. upto 10 wt. % crosslinker and coating the electrical conductor with this paste at or slightly above ambient temp. then hardening the coating and opt. crosslinking by gelling at 80-250 deg.C. More spec. (II) is an uncrosslinked homo- co- or graft co-polymer of 50-100 wt. % VC and 0-50 wt. % (III) with K value 70-100 which is made into a paste without (IV) or a copolymer of the same compsn. which is made into a paste contg. 0.1-10 wt. % S-contg. bifunctional crosslinker, (II) contains 0.1-20 wt. % (IV) or N-methylyl gp. contg. comonomer (V) and no crosslinker or 0.1-20 wt. % unsatd. hydrolysable silicon-functional comonomer and 0.01-10 wt. % acid catalyst or 0.1-20 wt. % OH-functional comonomer (V) and 1-10 wt. % di-isocyanate (II) is made into a paste with a crosslinkable plasticiser. USE/ADVANTAGE - Use of uncrosslinked (II) with high k value, or crosslinked (II), applied as a paste, gives cable sheathing with very low shrinkage at high temp.