GB911427A - Improvements in or relating to the manufacture of mouldings - Google Patents

Abstract

A method of moulding manufacture comprises treating a body of foam-like form such as polyurethane foam with a hard setting resin, forming the treated body to the required shape in a mould, and allowing curing of the resin to take place whilst the body is in the mould. Dry polyurethane foam, e.g. in strip form 2 or 3 inches wide and 6 feet long, is immersed in a resin, e.g. a polyester, epoxy, or resorcinolformaldehyde resin which may contain an appropriate catalyst and accelerator or hardener, in order to impregnate it with the resin, after which resin in excess of that necessary to wet or coat the interstices of the foam is removed by subjecting the foam to pressure, such as between rollers. The moulding surface(s) of the mould are first treated with a parting agent such as a suitable wax and, where a smooth non-cellular finish is required to the moulding, a facing coating is also applied. This may, for example, be the same resin used for impregnating the foam together with a hardener and mineral filler (e.g. French-chalk) with or without a thyxotropic agent and/or a pigment. The finished mouldings are both light and rigid owing to their porous texture and the fact that the cell walls are coated with the cured resin. Their impact strength may be improved by incorporating polysulphide polymers in the hard setting resin. The mould may be coated with the impregnated foam in strip form and laminates may be built up, the strips and/or sheets being joined by means of the impregnating resin. Metal inserts or reinforcements may be included in the moulding as it is being formed. The manufacture of panels for vehicle bodies, doors, and mudguards is referred to. The mould itself may be produced by the same method of manufacture, i.e. of impregnated polyurethane foam cured and preferably facing coat finished as above, or else made of a cured mixture of an epoxy resin, a hardener, a filler, and chopped strand glass fibres.