GB482836A - Improvements in or relating to the manufacture of plates, sheets or other shaped or moulded articles - Google Patents

Abstract

Raw shaped or moulded articles consisting essentially of one or more polyvinyl compounds are coated on one or more surfaces with a thin coating (such as produced by dipping or painting) comprising one or more monomeric or partially polymerized vinyl compounds and the applied coating is polymerized in contact with a mould or plate. Polyvinyl compounds specified are interpolymers or mixtures of polymers of (a) acrylic or methacrylic methyl, ethyl and butyl esters, or (b) styrene with vinyl acetate, acrylic nitrile, or both. The monomers or partial polymers applied may correspond to the polymer being coated. The moulds used may have highly polished surfaces, e.g. of metal or glass or be constructed of wood or plaster of Paris, and they may be lined with an adhesion-preventing coating, e.g. of gelatine, glycerine, soap, or regenerated cellulose or be powdered, e.g. with talcum. Polymerization may be caused by heat and pressure, e.g. by mechanical pressure or fluid pressure on all sides, applied to a mould disposed in an autoclave. There may be produced clear transparent plates, blocks, or moulded articles, e.g. lenticular screens, artificial parts of the body (e.g. for dental purposes) from polymeric bodies clouded or scratched on their surfaces. Pieces of the same or different polymers may be joined together, and plates produced with fabric or metal inserts. In examples: (1) rough plates cut from a block of poly-ethyl methacrylate are immersed in the corresponding monomer containing benzoyl peroxide and hot-pressed between glass plates; (2) a rough plate of an interpolymer of methyl methacrylate and butyl acrylate, cut from a block or produced by polymerization in a flat mould, is coated by pouring over it the corresponding mixture of monomers, and hot-pressed under a metal negative of a lenticular screen; (3) a plate of polymethyl methacrylate is coated with the corresponding monomer and hot-pressed under a second plate of the same material to form a single block suitable for use as a glass substitute; several plates may be united in this way; (4) a negative of a technical or artistic article is coated with a slightly polymerized mixture of methyl methacrylate, ethyl acrylate, and benzoyl peroxide, a rough positive made of the corresponding interpolymer laid therein and hot-pressed. Specification 433,540 is referred to.ALSO:Raw shaped or moulded articles consisting essentially of one or more polyvinyl compounds are coated on one or more surfaces with a thin coating (such as produced by dipping or painting) comprising one or more monomeric or partially polymerized vinyl compounds and the applied coating is polymerized in contact with a mould or plate. Polyvinyl compounds specified are interpolymers or mixtures of polymers of acrylic or methacrylic methyl, ethyl and butyl esters, of styrene with vinyl acetate, acrylic nitrile, or both. The monomers or partial polymers applied may correspond to the polymer being coated. The moulds used may have highly polished surfaces, e.g. of metal or glass or be constructed of wood or plaster of Paris, and they may be lined with an adhesion-preventing coating, e.g. of gelatine, glycerine, soap, or regenerated cellulose or be powdered, e.g. with talcum. Polymerization may be caused by heat and pressure, e.g. by mechanical pressure or fluid pressure on all sides, applied to a mould disposed in an autoclave. There may be produced clear transparent plates, blocks, or moulded articles, e.g. lenticular screens, artificial parts of the body (e.g. for dental purposes) from polymeric bodies clouded or scratched on their surfaces. Pieces of the same or different polymers may be joined together, and plates produced with fabric or metal inserts. In examples: (1) rough plates cut from a block of poly-ethyl methacrylate are immersed in the corresponding monomer containing benzoyl peroxide and hot-pressed between glass plates; (2) a rough plate of an interpolymer of methyl methacrylate and butyl acrylate, cut from a block or produced by polymerization in a flat mould, is coated by pouring over it the corresponding mixture of monomers, and hot-pressed under a metal negative of a lenticular screen; (3) a plate of polymethyl methacrylate is coated with the corresponding monomer and hot-pressed under a second plate of the same material to form a single block suitable for use as a glass substitute; several plates may be united in this way; (4) a negative of a technical or artistic article is coated with a slightly polymerized mixture of methyl methacrylate, ethyl acrylate, and benzoyl peroxide, a rough positive made of the corresponding interpolymer laid therein and hot-pressed. Specification 433,540, [Group IV], is referred to.