GB835822A - Improvements in or relating to moulds, jigs and like structures - Google Patents

Abstract

Moulds, jigs, and like structures are made by applying to the surface of a pattern in the following sequence: (i) a synthetic resin surface coat, particularly one which may be hardened at room temperature, e.g. an unsaturated polyester or an epoxide resin; (ii) a woven or mat sheet of a fibrous material, e.g. glass fibres; and (iii) a mixture of a lightweight filler and a synthetic resin binding agent, e.g. an epoxide or polyester resin as in (i) and allowing the synthetic resin in the composite article to harden. The surface coat usually contains a mineral filler, e.g. slate dust, and a thixotropic agent, e.g. silica aerogel. The lightweight filler may consist of hollow particles formed from synthetic resinous materials, e.g. phenol-formaldehyde or polystyrene resin or naturallyoccurring materials which have been heat-treated to reduce their bulk density to less than 20 lb/cu. ft., e.g. perlite or vermiculite. It is customary to allow the surface coat to gel in which case a second surface coat and/or a layer of adhesive is applied before covering with the fibrous material which is preferably glass-fibre. If greater strength is needed a further layer of fibrous material may be applied after the mixture containing the lightweight filler.ALSO:Moulds, jigs, and like structures are made by applying to the surface of a pattern in the following sequence (i) a synthetic resin surface coat, particularly one which may be hardened at room temperature, e.g. an unsaturated polyester or an epoxide resin (ii) a woven or mat sheet of a fibrous material, and (iii) a mixture of a lightweight filler and a synthetic resin binding agent, e.g. an epoxide or polyester resin as in (i) and allowing the synthetic resin in the composite article to harden. The surface coat usually contains a mineral filler, e.g. slate dust, and a thixotropic agent, e.g. silica aerogel. The lightweight filler may consist of hollow particles formed from synthetic resinous materials, e.g. phenol-formaldehyde or polystyrene resin or naturally-occurring materials which have been heat-treated to reduce their bulk density to less than 20 lb./cu. ft., e.g. perlite or vermiculite. It is customary to allow the surface coat to gel in which case a second surface coat and/or a layer of adhesive is applied before covering with the fibrous material which is preferably glass-fibre. If greater strength is needed a further layer of fibrous material may be applied after the mixture containing the lightweight filler.