GB1171116A - Improvements in or relating to Covered Sheet Material. - Google Patents

Abstract

1,171,116. Laminates. E. A. DUFFIELD. 19 Dec., 1966 [18 Dec., 1965], No. 53760/65. Heading B5N. A composite sheet material comprises a basic or board material provided on one or both faces with a composite covering formed from a plurality of laminae, each lamina being of a porous nature and having bonded to it, with a natural or synthetic resin, a mineral powder having a particle size not greater than 50 B.S.S. mesh, the weight ratio of mineral powder to resin being at least 1:1, and the basic or board material and laminae being compressed to an extent such that stratification is removed. The basic or board material is preferably absorbent and may be composed wholly or partially of organic or inorganic fibres, e.g. it may be electrical insulation sheet, hardboard, building board made from organic or inorganic fibres with or without a binder, felted mineral fibres with an organic binder, asbestos cement board, plywood, or chipboard. The laminae may be paper of cellulose or mineral structure, cloth sheet, e.g. textile fabrics and linen, or open weave mineral fabric, e.g. silica or glass fabric or glass fibre sheet. The resin may be Indian lac or a phenolic, epoxy, vinyl acetate polymer, polyester, urea, melamine or silicone resin. In particular thermoplastic resins, e.g. vinyl chloride polymers, polyethylene, polypropylene, polystyrene, acrylic or methacrylic resins, e.g. "Perspex" (Registered Trade Mark) or P.T.F.E. may be used. The mineral powder may be slate, steatite or mica. The composite material may be prepared by treating the basic or board material by roller coating or bath impregnation with a liquid mixture of resin and mineral powder, and placing laminae treated with mineral powder and resin on one or both faces of the basic or board material. Heat and pressure are then applied to bond the layers and cure the resin. If the resin is cold-setting the heat is not necessary. In Example I a hardboard core is roller coated with a liquid mixture of "Bakelite" (Registered Trade Mark) and slate powder and a three sheet laminate of paper coated with the same mixture is placed thereon before bonding and curing by heat and pressure. In Example 2 a partially dried pulp of fibre board, which when dry will form a core of felted mineral fibres, is sprayed with a suspension of powdered slate in urea formaldehyde resin. Resin treated laminae are then applied and bonding, curing and drying effected by heat and pressure. If desired the pressure may be applied in two stages, first slightly whilst melting the resin, and then fully whilst curing the resin. The composite material formed is resistant to fire, water, chemical action and ultra-violet light.