Verfahren zur Herstellung von verharzbaren,in der Waerme haertenden verstaerkten Harzen

Siliceous fibres, e.g. glass, rock wool and fused quartz fibres which are to be used for reinforcing thermo setting resin compositions are treated with a polymeric size comprising an aqueous dispersion or organic solvent solution of a homopolymer of a C4-C7 isoolefin or a copolymer of at least 70% by weight of a C4-C7 isoolefin with up to 30% by weight of a C4-C10 conjugated diolefin, the polymeric size removed by pyrolysis and the fibres then impregnated with the resinifiable thermo setting composition. The isoolefin may be isobutylene or 2-methyl-1-butene and the diolefin may be isoprene, butadiene or piperylene. Aqueous dispersions may contain 1-3% of the polymer together with a nonionic emulsifier e.g. a polyoxy ethylated octyl or nonyl phenol containing 8-10 ethylene oxide units and organic solvent solutions may comprise 1-3% by weight of the polymer dissolved in hexane, heptane, an ester, an ether or mixtures thereof. The size may be applied to the fibres as they are being formed and the fibres then dried at 60 DEG -300 DEG F. for 1 minute to 10 hours. After fabrication of the fibres into rovings, cloth or matting the size maybe removed by heating to 500 DEG -900 DEG F. for 5 seconds to 2 minutes. The size composition may also contain a silanol having the formula in which X is avinyl, crotyl, allyl or cyclo hexenyl radical and A and B are hydroxyl, chloro, bromo, methoxy, ethoxy, propoxy, methyl, ethyl or propyl groups. Alternatively X may be the group Y-X- in which X is an alkyl radical and Y is an amino, mercapto, hydroxyl, cyano, carboxy, epoxy, quinoyl, oxime or sulpho group. The silanol is not removed from the fibres by the pyrolysis. Alternatively the silanol may be incorporated into the resinifiable thermosetting composition applied subsequently. The thermosetting resin may be a polydiolefin polyester, epoxy, silicone phenol or melamine resin, preferred polymers comprising the drying oils obtained by polymerizing conjugated diolefins having 4-6 carbon atoms with a cross linking agent e.g. styrene, using an organic peroxide as catalyst. The resinifiable thermosetting composition, e.g. a polydiolefin may contain crosslinking agents, e.g. styrene, vinyl toluene, halostyrenes vinyl naphthalenes, alkyl acrylates and methacrylates and allyl esters and catalysts, e.g. dicumyl peroxide and/or ditert. butyl peroxide.