Patent GB-1451769-A (GB)
Title: Production of pattern-bearing surface coatings
IPC: B44C3/04
Filed: 1972-07-19
Abstract: 1451769 Decorative coating BERDEN REPRODUCTIONS Ltd 18 July 1973 [19 July 1972] 33738/72 Heading B2E [Also in Division G2] A pattern-bearing surface coating resembling an inlay is produced by coating a substrate with a layer comprising a photocurable synthetic resin which forms a solid cured resin on exposure to irradiation, subjecting the layer to selective irradiation through a masking layer bearing the pattern such that the photocurable resin is polymerised only in those areas of the pattern where the masking layer is transparent to the radiation, removing the uncured material from the layer without affecting the substrate, thereby forming a relief pattern on the surface of the substrate, filling the depressions in the relief pattern with a hardenable material of contrasting appearance to the cured resin and hardening the hardenable material to form a surface coating, the surface of which is formed in the parts corresponding to the transparent areas of the masking layer by the cured synthetic resin and in the remaining parts by the hardened hardenable material. The photocurable material may be a polyurethane, epoxy or a liquid polyester resin. The substrate may be solid wood or veneer or chip-board and may be pre-coated with a sealing layer which may be a photopolymerisable material which is then cured uniformly. The substrate may also be coated with a pattern layer such as imitation wood grained layer. Liquid photocurable material may be heated in absence of polymerisation-initiating radiation prior to application to the substrate to remove entrapped air bubbles. The hardenable material is preferably a polyester resin introduced as a paste or viscous liquid. The depressions may be overfilled initially, or alternatively filled level or underfiled initially. After the hardenable material has cured the surface may be sanded and burnished. The process is suitable for making inlaid table tops, chess boards using a wood, chip-board substrate, and for the production of relief patterns on webs of flexible material, e.g. polyamide or polyester textile material for use as curtains. As shown in the drawing substrate 10 in the form of a chip-board panel coated with a sealant layer of polyester resin and pre-cured is provided round its edge with a removable raised edging 12 and placed on a rigid horizontal base 11. A layer 13 of liquid photocurable polyester resin composition is poured into the shallow trough formed by the edging 12 and a taut transparent polyethylene film 14 mounted on a frame 15 is placed over the liquid layer and rolled with a heavy chrome plate of roller to ensure intimate contact with the liquid layer. A masking layer 16 consisting of a transparent plastics film bearing an opaque pattern is then accurately positioned on the top of the film 14 and the assembly brought into position under the irradiation system consisting of a battery of ultra-violet lamps 17 and a liquid filtering and cooling system 18. The filtering and cooling system consists of a divided bath having a low compartment 19 containing a dilute aqueous sulphuric acid/copper sulphate solution and an upper compartment 20 containing cooling water and provided with inlet and outlet pipes for the continuous circulation of the cooling water to an external cooler. After irradiation uncured polyester resin is removed by scrubbing with solvent and the depressions filled with a pigmented liquid polyester resin.