GB1152724A - Method of Moulding Rigid Composite Articles. - Google Patents

Abstract

1,152,724. Moulding rigid articles. A. H. ROBERTS. 13 May, 1966, No. 2317/69. Divided out of 1,152,723. Heading B5A. Rigid articles comprising an outer skin backed by a rigid material are made by moulding a layer of plastics or elastomeric material in an undercut mould, deforming said layer and removing it from the mould, applying a solidifiable liquid material through a hole in said layer, and finally solidifying the liquid material to form a rigid backing for said layer. The backing may comprise one or more layers to give a hollow article or may comprise a mass completely filling the layer to give a solid article. In the former case additional reinforcements such as resinous layers, solid resinous masses of e.g. formed polyurethane, metal tubes or chipboard and cardboard sheets may be located within the backing layers. The skin may be slip, slush or rotationally cast, vacuum or blow moulded, injection moulded or extruded and the backing material may be applied by brushing, spraying, slush moulding, or rotational casting. The skin is either unsupported during the application of the backing material or is supported by a singlepiece or multi-piece mould. A mould of the former type may be made by dipping or spraying the skin with, for example plaster of Paris or a low melting point metal, the material being removed after the application of the backing. Materials suitable for use as the skin are P.V.C. plastisols; polyethylene; natural or synthetic rubber; methyl methacrylate; ethylcellulose; cellulose acetate or acetobutyrate; polycarbonate; a polyurethane elastomer; flexible epoxy compounds; or a pollyalomer. Materials suitable for use as the backing layer or layers fall broadly into 3 classes: (a) a composition comprising a filler plus an emulsion or a latex; (b) a rigid cellular plastics material, and (c) a rigid polyester or epoxy resin. Alternatively asphalt, cement or plaster of Paris are suitable. Latices used in (a) may be based upon natural or synthetic rubber, P.V.C., polyvinylidene chloride, a vinyl chloride-acrylic copolymer, or an ethylene-proplyene copolymer, and the fillers used may be fine, such as the various well known colouring pigments or coarse, such as clay or vitreous rock particles, and may contain asbestos or glass reinforcing fibres. Examples of foams which fall into class (b) are polyurethane, epoxy, P.V.C. cellulose acetate, acrylic, asphaltic, phenolic, silicone, low density polyethylene or urea formaldehyde foams.