GB441622A - Improvements in or relating to the coating of materials - Google Patents

Abstract

Sheet materials or articles are coated by <PICT:0441622/III/1> applying thereto a layer of a thermoplastic composition prepared by grinding a thermoplastic substance in the presence of a nonsolvent and removing the non-solvent, causing the layer to adhere to the surface by the application of heat and pressure, and supplying heat during the pressing operation to, and/or withdrawing heat immediately after the pressing operation from, the thermoplastic layer through the said surface. The grinding may be effected in a colloid mill having abrasive discs, as described in Specification 428,456. The thermoplastic composition may be prepared from a cellulose ester such as the nitrate, acetate, formate, propionate or butyrate, or an ether such as methyl, ethyl, or benzyl cellulose, or from rubber, halogenated (e.g. chlorinated) rubber, resins, e.g. vinyl resins such as polyvinyl acetate or polystyrol, or from two or more of these substances, with or without plasticizers, dyes, pigments, lakes, fillers, resins, oils, &c. Suitable plasticizers are camphor, diethyl or dibutyl phthalate, triphenyl or tricresyl phosphate, and ethyl paratoluene sulphonamide. The composition may be applied as a powder, or may be formed into a layer continuously with its application to the surface by passing the composition in the form of powder, grains, blocks, slabs, or strips between a series of heated rollers. Cardboard, pulp, &c., sheets, blocks, strips, &c., of wood, cork, rubber, asbestos board, metals, glass, slate, &c., and rods, profile strips, tubes, mouldings, corset stays, lead pencils &c., may be coated. As shown, a thermoplastic composition in a hopper 1 is formed by the action of heated rolls 2--5 driven at the same or different peripheral speeds, into a layer which is applied to rigid sheets, panels &c., of wood, asbestos, metal &c., as they pass over a heated roll 12 situated between heated and cooled tables 13 and 15, the surfaces of which are preferably level with the crown of the roller 12, the tables and roller 12 being adjustable in height relatively to the roller 5. By supplying differently-coloured powders, blocks, ribbons, &c., of the thermoplastic composition to hopper 1, variegated or striped effects are obtained. Embossed metallic or hard surfaces may be coated so as to fill only the depressions giving an inlay enamel effect. Metal sheets &c., when coated may be stamped, drawn, rolled, milled, &c. Two examples of plasticized cellulose acetate compositions are given. The Specification as open to inspection under Sect. 91 describes coating materials or articles with thermoplastic compositions free from volatile solvents or liquids with the aid of heat and pressure. This subjectmatter does not appear in the Specification as accepted.