GB1461255A - Laminating process - Google Patents

Abstract

1461255 Laminates IMPERIAL CHEMICAL INDUSTRIES Ltd 5 Feb 1974 [9 Nov 1972] 51682/72 Headings B5N and B5A A laminate comprising at least one rigid alumina bonded to at least one glass lamina which forms a surface of the laminate, is produced by a process in which bonding is brought about by photopolymerization of an ethylenically unsaturated material comprising at least one ethylenically unsaturated monomer in the presence of a photoinitiator system capable of initiating polymerization of the monomer when exposed to radiation of suitable wavelength, the photoinitiator system comprising a photosensitizer and a reducing agent capable of reducing the photosensitizer when the latter is in an excited state. The glass lamina may be bonded to the rigid lamina which may be of wood, metal, glass, concrete or solid or foamed polymer material, e.g. polyurethanes, amino resins, polyesters, polycarbonates or polyacrylates, optionally containing fibrous reinforcement, e.g. polyethylene terephthalate, nylon, glass or carbon fibre, pigments and other fillers, by photopolymerization of an adhesive comprising the ethylenically unsaturated material. Alternatively the rigid lamina itself may be a polymer formed by photopolymerization of the ethylenically unsaturated material in contact with the glass lamina, e.g. in a mould. The ethylenically unsaturated monomer may be styrene, vinyl toluene, divinyl benzene, methyl methacrylate, methacrylic acid, ethyl acrylate, vinyl acetate, acrylonitrile or N-vinyl pyrrolidone or a mixture thereof, which may be used in admixture with isocyanates, polyols, unsaturated polyesters, polyethers, polystyrene and polymethyl methacrylate. The -photosensitizer may be a compound of the formula in which X is >C=O, >CR 1 R 2 or >CR 3 OR 4 , in which R 1 to R 4 are hydrogen or hydrocarbyl groups, n is 0 or 1 and the groups A are hydrocarbyl or substituted hydrocarbyl groups, the groups A being aromatic or substituted aromatic when n is 1 and X is >CR 1 R 2 and when n is 0, e.g. benzil, and the reducing agent may be a primary, secondary or tertiary amine, e.g. dimethylaminoethyl methacrylate or dimethylaminoethanol. Visible or ultraviolet light may be used for the polymerization reaction. The adhesive may contain a particulate or fibrous reinforcement material, e.g. a printed lightweight or open-mesh fabric. Glass/interlayer adhesion may be improved using newly formed glass, a glass lamina chemically treated with trimethoxy vinyl silane, an adhesive containing polar hydrophilic groups, e.g. a vinyl urethane resin, or adhesive having a low shrinkage during curing. Laminates comprising a thin layer of low melting glass bonded by a photopolymerizable adhesive layer to a thermoplastic lamina or partially cured reinforced thermosetting material layer or a thin layer of low melting glass bonded to a glass fibre reinforced uncured photopolymerizable unsaturated polyester resin, may be softened by heating and shaped, e.b. by winding on to a cylindrical mandrel to form a pipe, prior to photopolymerization and curing.