GB654645A - Improvements in or relating to the manufacture of thermo-set plastic laminates, and the products of such manufacture - Google Patents

Abstract

654,645. Compound sheet materials. HOLOPLAST, Ltd., and GONDA, D. April 11, 1947, Nos. 9722/47 and 9130/48. [Class 140] [Also in Group XVI] A plurality of thermoset plastic laminates each comprising a number of superposed sheets of fibrous material (e.g. paper, wood veneer, woven glass fibre, asbestos, fabric), impregnated with a thermosetting resin such as phenolformaldehyde, urea-formaldehyde or melamineformaldehyde resin, are simultaneously formed by superposing assemblies 1 of such sheets with a separating layer 6 between each assembly, pressing the superposed assemblies in a single daylight 3, 4, of a press and finally removing the separating layers. The separating layers obviate lubrication and facilitate stripping. The products are stated to have a "hammered" appearance due to irregularities in the sheets being consolidated particularly when these are of kraft paper. The separating layers may be sheet or film regenerated cellulose, copper, brass, zinc or aluminium foil, or unplasticized polyvinyl chloride. Caul plates 5, 8 may be placed above and below the superposed assemblies and a separating layer 6 between the caul plates and top and bottom assemblies. A moulding element 7<SP>1</SP>, which may be a rigid plate or sheet, e.g. of metal or thermoset laminate having a figured surface, wire gauze, fabric, a perforated plate or a number of sheets (as shown), of kraft paper which has scattered hard and soft areas, may also be interposed between successive assemblies or above and/or below the top and bottom assemblies to mould the surface or surfaces of the laminate to a desired form which may be different for different surfaces. Where the assemblies or the surface sheets thereof are of impregnated kraft paper, textile fabric, lace, wood veneer or glass fibre, they will themselves act as moulding elements for adjacent assemblies. When perforated plates 13 are used a number of sheets of kraft paper or other moulding element 7<SP>1</SP> may be used to mould the surface of the parts of the assemblies projecting through the perforations or these may be made smooth by the caul plates. The laminates may be pressed to forms other than flat, e.g. corrugated. The Provisional Specifications refer also to the moulding of a single laminate and the first Provisional Specification to laminates with comparatively smooth surfaces on both sides using the normal polished metal separating plates with separating layers between the plates and impregnated assemblies. Specification 546,089 is referred to.