| 摘要 |
Storable reinforced unsaturated polyester resin sheets which are capable of being shaped mechanically are prepared by (a) treating a permeable layer of reinforcing material with a polymerization initiator comprising a salt of a polyvalent metal or of boron, (b) impregnating the treated layer with an unsaturated polyester resin composition containing a polymerization catalyst and partially polymerizing the composition to the gel stage and (c) subjecting one or both faces of the impregnated layer to the action of heat and/or a polymerization accelerator to form a thin, more fully polymerized surface layer. The accelerator may be used in admixture with a mono- or di-isocyanate. The initiator may be a halide, sulphate or naphthenate of tin, iron, zinc, aluminium, cobalt or manganese; it may be dissolved in ethylene glycol and diluted with ethanol or a suitable monomer, e.g. vinyl acetate. The polymerization catalyst may be benzoyl peroxide and the unsaturated polyester resin composition may also contain an inhibitor, e.g. 4-methyl-2,6-di-t-butylphenol and a filler, e.g. calcium carbonate. The resin used in the example is a polyester of ethylene glycol and maleic and phthalic anhydrides and adipic acid mixed with methyl styrene. Styrene may also be used as comonomer. The reinforcement may be a natural or man-made fibre or fabric, e.g. glass fibre or paper. The accelerator may be a mono- or di-alkyl aniline or an alkylaryl or diaryl guanidine; it may be applied in admixture with a modifying agent for the resin, e.g. toluene diisocyanate, and a lubricating agent, e.g. mixtures of mono- and di-alkyl phosphates and/or waxes, e.g. stearamide or polyethylene wax or hydrogenated castor oil. |
