| 摘要 |
<p>1,179,631. Foamed plastics laminate. W. R. GRACE & CO. 30 March, 1967 [13 May, 1966], No. 14612/67. Heading B5N. A sandwich structure comprises two sheets secured by adhesive to a polystyrene foam core; at least one of the sheets comprising a thermoplastic resin composition having therein a fibrous filler consisting of asbestos and/or glass fibres, organic fibres, or a mixture of asbestos and cellulosic fibres, the fibres being less than 2 inches long and comprising from 20% to 60% by weight of the sheet. The outer sheets may both be of the filled thermoplastic resin composition or one of them may be of plywood, metal, wallboard, ceramics, fibreglass or plastics. The foam core is preferably produced from preexpanded particles, i.e. particles formed by mixing particles of polystyrene and a blowing agent and partially evaporating the blowing agent by heat, e.g. hot water, steam or infrared, the core being produced by heating the preexpanded particles together in a mould, or between continuous belts, to form a preformed core, which may have tongue and groove or strip lap edges, or by expanding the particles between the outer adhesive-coated sheets either in a mould, or continuously, heat being applied to effect the foaming in situ e.g. dielectric heating. The foam may include fire-resistant additives e.g. antimony oxide or alkyl acid phosphate, fillers, e.g. clay, calcium sulphate or ammonium phosphate, dyes, and glass, asbestos or synthetic fibres. The outer sheet comprising the thermoplastic composition is preferably rigid and the thermoplastic is preferably PVC although it may be a polymer of one or more of styrene, methylmethacrylate, acrylonitrile, and vinyl chloride, or a copolymer or terpolymer e.g. of styrene and butadiene, or A.B.S., or a mixture of polystyrene with a styrene/butadiene copolymer or with a styrene/maleate ester copolymer. The fibres present in the outer sheet may be of glass, asbestos, wood, paper, cellulosic material, or textile fibres of vegetable or animal origin e.g. leather. The sheet may be produced from a slurry of the fibres and a dispersion of plastics particles by mixing these and using a paper-making machine to produce sheets of filled resin. The sheet may comprise one or more of these sheets welded by heat and pressure. Alternative layers of a dough-like material composed of a plastisol and the fibres are laid up on a calender comprising hot and cold bowls. The layers may be reheated and pressed hydraulically or between hot and cold rolls to consolidate them into a sheet. The sandwich structure is formed by sticking the sheets to the core by an epoxy resin adhesive or by an adhesive set by hot air, or is formed by continuously producing foam between two continuous sheets, or, as above, by expanding the foam in situ between the sheets. The outer sheets may be transparent, weather-resistant or fire-resistant. The sandwich structures may be used as building panels.</p> |
