GB805388A - Improvements in or relating to laminated structures - Google Patents

Abstract

Surfaces are coated with films of polyvinyl fluoride containing 5 to 50 per cent, preferably 5 to 20 per cent, of a solvent, by subjecting the film and substrate to heat and pressure to remove substantially the whole of the solvent. The solvent must have a boiling point between 100 DEG and 250 DEG C. and be capable of partially dissolving the film at a temperature below that boiling point; it is preferably non-solvent at room temperatures. When the solvent is one in which the polymer is appreciably soluble at room temperature, e.g. hexamethyl-phosphoramide, the solvent activity may be reduced by the addition of a non-solvent liquid, such as acetone, ethylene glycol, or benzene. Examples of suitable solvents are: N,N-dimethylformamide; N,N-dimethyl-acetamide; cyclohexanone; acetophenone; tetramethylurea; cyclic ethylene carbonate; camphor; nitrobenzene; phenol; iso-phorone; propylene carbonate; acetonylacetone; mesityl oxide; gamma-butyrolactone; iso-quinoline; organic phosphates; and keto-esters, e.g. ethyl acetoacetate. Films containing uniformly dispersed solvent may be prepared by forming an organosol or by forming a plastisol. Films may be formed from the organosols by coalescing them on a non-adherent surface, of e.g. metal, and driving out a desired amount of solvent to form a film containing at least 5 per cent residual solvent. Plastisols may be formed into films by calendering or by extrusion at elevated temperature. Suitable substrates include: building boards including solid wood, plywood, wood veneers and pressed woods, paper, cardboard, boards made from rags and bagasse, plastic boards, gypsum boards, asbestos boards and panels made of cork; boards or panels reinforced with glass fibres and boards impregnated with thermoplastic or thermosetting synthetic resins; boards prepared from cellular polystyrene, cellulose acetate, polyvinyl chloride and other synthetic resins; metals, particularly in the form of sheets such as aluminium, steel, copper and chromium; masonry surfaces such as cinderblock and cement blocks; films and fabrics of polyamides, polyesters, polystyrene, polyethylene or polymethyl methacrylate. When coating metals, the metal surface may first be roughened, e.g. by light abrasion with pumice, wirecloth or sandpaper. An adhesive layer between the substrate and the polyvinyl fluoride may be used; suitable adhesives include: phenol-formaldehyde, resorcinol-formaldehyde, urea-formaldehyde and melamine-formaldehyde resins, polyester resins, epoxy resins, silicone resins, polyvinyl resins, polyacrylates, natural rubbers, synthetic rubbers (e.g. butadiene/acrylontrile and butadiene/styrene copolymers) and mixtures of natural rubber with synthetic resins. The polyvinyl fluoride film may be a molecularly oriented film produced from polyvinyl fluoride having an inherent viscosity of at least 0.35. Rods, pipes and tubes may be wrapped by the process, and successive layers may be superimposed on one another. Specification 605,445, [Group IV (a)], is referred to.ALSO:Films comprise polyvinyl fluoride containing 5 to 50 per cent, preferably 5 to 20 per cent, of a solvent. The solvent must have a boilingpoint between 100 DEG and 250 DEG C. and be capable of partially dissolving the film at a temperature below that boiling point; it is preferably non-solvent at room temperatures. When the solvent is one in which the polymer is appreciably soluble at room temperature, e.g. hexamethyl-phosphoramide, the solvent activity may be reduced by the addition of a non-solvent liquid, such as acetone, ethylene glycol, or benzene. Examples of suitable solvents are N,N - dimethyl - formamide; N,N - dimethylacetamide; cyclo-hexanone; acetophenone; tetramethylurea; cyclic ethylene carbonate; camphor; nitrobenzene; phenol; iso-phorone; propylene carbonate; acetonylacetone; mesityl oxide; gamma-butyrolactone; iso-quinoline; organic phosphates; and keto-esters, e.g. ethyl acetoacetate. Films containing uniformly dispersed solvent may be prepared by forming an organosol or by forming a plastisol Films may be formed from the organosols by coalescing them on a non-adherent surface, of e.g. metal, and driving out a desired amount of solvent to form a film containing at least 5 per cent residual solvent. Plastisols may be formed into films by calendering or by extrusion at elevated temperature. The polyvinyl fluoride film may be a molecularly oriented film produced from polyvinyl fluoride having an inherent viscosity of at least 0.35. The films are used as coatings (see Group III). Specification 605,445 is referred to.