Patent GB-1458253-A (GB)
Title: Multicoloured reflective articles
IPC: G02B5/128
Filed: 1974-03-01
Abstract: 1458253 Multi-coloured coated products YANKEE ARTISTS Inc 1 March 1974 [28 June 1973] 9288/74 Heading B2E Multicoloured decorative or functional structures such as signs and markers comprising a solid substrate with a superimposed transparent solid layer of resinous material having one or more coloured areas are produced by covering at least one selected area of a solid substrate having a transparent surface layer of colour-receptive resinous material, with a resin film overlay so that the overlay becomes affixed to the transparent layer, while leaving another area exposed, and applying a liquid colourant to the surface of the article while the overlay is in a hardened non-porous condition resistant to the liquid colourant, to colour the exposed area of the surface layer while the area covered by the overlay remains colourless. The solid substrate may be a reflex-reflective material such as a retroreflective optically enclosed system containing transparent spheres. The overlay may be opaque or transparent, and coloured or colourless, and of a different colour from the liquid colourant. The article may be provided with an outer coating of transparent weather-resistant material. The liquid colourant may be a dye solution or a dispersion of solid pigment, or a precursor material capable of reacting in situ to form a coloured material. The overlay is suitably applied in liquid form and then hardened prior to the colouring step. A first layer of such liquid comprising a resinous composition containing one colourant material may be printed on to selected areas of the transparent layer and then hardened, followed by printing of a differently coloured resinous composition on to other areas and then hardening, and a colourant dye solution then applied so that areas of the transparent layer still uncovered by the two overlays become coloured. In Fig. 1, a retro-reflective substrate composed of a mirror-like reflector 12 which may be polished aluminium or a silver coating on a transparent spacing layer 14 which carries a layer of glass beads 16 at the proper distance from the reflector 12 to provide a reflexreflecting effect, and a bead-securing layer 18 with a bead-enclosing layer 20 (e.g. of polymethylmethacrylate) to provide a flat-surfaced exterior, is covered with a layer 10 of transparent dyeable resin. Alternatively the beadenclosing layer 20 may itself consist of a suitable dyeable resin. The substrate may have a reinforcing backing (e.g. corrugated paperboard, a metal plate, or a glass-fibre reinforced plastics material sheet laminated 'thereon) and/ or a pressure sensitive layer on 'the exterior face of the reflecting element 12 or reinforcing backing. The overlays 22 in Fig. 2 are then applied on selected areas of the layer 10, in liquid form as a solution in a volatile solvent or as a solvent-free curable resin composition, and suitably hardened (e.g. drying, heating to cure, or by a catalyst), or alternatively applied as preformed sheets bonded by adhesive or a laminating procedure. The overlays as liquid may be applied by offset, gravure or letterpress printing, spraying or brushing freehand or through stencils, by silk screening, or by roller coating on to raised patterns on an embossed subtrate. Subsequently, colourant material (e.g. on appropriate dye solution) is more or less generally applied to the surface, by immersion, spraying or roller coating, followed by removal of surplus colourant to leave dyed areas 26 in Fig. 3 where the dye-receptive layer 24 is not covered by overlay 22, and clear areas where the colourant has been removed from the dyeresistant overlay areas. Finally a weatherresistant transparent colourless outer coating (e.g. an acrylate resin) may be applied to the entire surface, by brushing, dipping, spraying or roller coating of a solvent based lacquer or a varnish, or by laminating as a pre-formed sheet. The dyeable layer 10 may be a methyl methacrylate polymer or copolymer with styrene or α-methyl styrene, cellulose acetate or nitrate, nylon, polycarbonate, polyethylene, polypropylene, polysulphones, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, ureaformaldehyde, vinyl butyral or vinylidene chloride, when the colourant material is a dyestuff in a polar solvent, or an alkyd resin when the dyestuff is in a non-polar solvent. The layer is applied as a thin film by dipping spraying, roller-coating or extrusion coating, of a liquid curable resin, a melt or a solution in a solvent. The dye-resistant overlay, which may be transparent or opaque, and clear or coloured, may be a thermoplastic or thermosetting resin, including acrylic resin (polymethylmethacrylate), cellulose acetate, triacetate, acetate-butyrate or ethyl cellulose, nylon polystyrene, polyvinyl chloride and its vinyl acetate copolymer, melamine-formaldehyde, polyvinyl alcohol, polyesters such as alkyd resins, epoxy resins and polyurethanes, and silicone resins such as alkyd polysiloxanes. Alkyd resins and silicone resins are used when the colourant liquid is in a polar medium, the others being preferred for use with non-polar colourant media. The colourant compositions may be solutions of a dyestuff in a polar or non-polar solvent, dispersions of pigments suitably with a binding agent, paints or enamels which may include opacifying fillers, and precursors for colourant formation which are subsequently treated to convert them to a pigment or coloured compound e.g. nioxime (1, 2-cyclohexanedione dioxime) which per se imparts a blue colour but, after treatment of selected nioxime-treated areas with aqueous nickel chlorine, becomes transformed to a pink colour. The expression "colourant composition" is intended to embrace material imparting black, white, silver or shades of grey.