IMPROVEMENTS IN OR RELATING TO THE PRODUCTION OF RUBBERS

1282285 Rubberized cloth VSESOJUZNY NAUCHNO-ISSLEDOVATELSKY INSTITUT SINTETICHESKOGO KAUCHUKA IMENI AKADEMIKA S V LEBEDEVA 17 July 1969 36045/69 Heading B5N [Also in Divisions C3 and D1] A rubberized cloth is obtained by laminating a rubber tape with a glass cloth impregnated with a solution of a similar rubber, the rubber composition comprising (a) a borosiloxane and/or a phosphoborosiloxane polymer having a B : Si ratio of 1 : 2-200 and a P : Si ratio, where P is present, of 1 : 10-300, (b) an uncured organopolysiloxane gum, (c) 10-30 p.b.w. per 100 of the siloxane polymers of a compound of a transition metal (of groups Ib, IIb, IIIb, IVb, Vb, VIb, VIIb or VIII of the Periodic Table), and (d) a reinforcing or semi-reinforcing filler. Preferred proportions are: (a) 2-50 p.b.w., (b) 50-98 p.b.w., (c) 10-30 p.b.w. and (d) 30-35 p.b.w., (a) and (b) totalling 100. There may also be present 1-5 p.b.w. of a low molecular weight polysiloxane, 1-10 p.b.w. of a dialkyl sebacate, 0À1-1 p.b.w. of a saturated fatty acid, and 0À5- 1 p.b.w. of PTFE. The rubber stock may be cured by irradiation or a peroxide, and is dissolved in an organic solvent used to impregnate glass cloth. In examples a polydimethysiloxane gum containing some vinyl groups is mixed with a borosiloxane or phosphoborosiloxane, a reinforcing silica filler and ferric oxide or hydroxide or zirconium oxide, and optionally acetic acid (Example 3), PTFE (Example 4) or a liquid polysiloxane (Example 5); the mixture is formed into sheets or tapes. In Examples 3-5 the tapes are pressed on to one or both sides of a glass cloth tape impregnated with a hydrocarbon solution of a similar composition containing also a precipitated silica, CaCO 3 and dioctyl sebacate. The tapes are cured by gamma irradiation or by a peroxide incorporated into the rubber.