Patent GB-656842-A (GB)
Title: Resin-surfaced laminated materials
IPC: D06P5/24
Filed: 1947-10-09
Abstract: 656,842. Compound sheet materials. BAKELITE CORPORATION. Oct. 9, 1947, No. 27199. Convention date, Oct. 19, 1946. [Class 140] [Also in Group XVI] Resin-bonded laminated fibrous sheet material is provided with a resinous surface layer consisting of the heat-hardenable resinous polyester described in Specification 644,597, [Group IV (a)], heat-hardened to form a hard, flexible, lustrous finish. A solution of the polyester may be applied to the surface of a previously-formed laminate, dried and partly cured, and the curing completed by hotpressing. The formation of the laminate may be combined with the coating operation, as by assembling a number of fibrous sheets impregnated with a phenol-formaldehyde resin, applying the polyester solution to the surface of the outermost sheet, drying and partly curing the polyester coating, and hot-pressing to cure the coating and heat-harden the phenol-formaldehyde resin. The fibrous sheets may be impregnated and bonded with the polyester. A solution of the polyester may be applied, e.g. in the form of a design, to a metal press plate or to a transfer sheet such as regenerated cellulose or aluminium foil, dried and partly cured, and subsequently transferred and bonded by heat and pressure to the surface of a resinbonded fibrous laminate, which may be simultaneously formed. The surfaced laminates may be used for table tops, wall boards, panelling having cork or other cores, and may be bent or post-formed into trays or instrument cases. A resin prepared from sorbic acid, adipic acid, and glycerine is used in solution in toluene, lauroyl peroxide being added just before application. In examples (1) cloth or paper impregnated with the catalysed polyester solution is laminated and hot-pressed ; (2) a metal press plate surface, which may be preliminarily treated with zinc stearate, is sprayed with a clear or pigmented resin solution, heated in an oven until the film was dry to the touch, the coated side of the press-plate is placed in contact with a stack of cloth sheets impregnated with phenol-formaldehyde resin, the assembly is hot-pressed, and the plate removed; (3) the process of example (2) is modified in that the polyester coating is applied in the form of a design, e.g. by block-printing, roller coating, spraying through a stencil, silk screen printing, or by a rubber stamp ; (4) and (5) a coating or design is printed on a regenerated cellulose sheet, or aluminium foil and transferred to a core stock of phenol-aldehyde resin-impregnated paper sheets ; (6) paper coated on one side is laminated to a stack of previously bonded fibrous sheets ; (7) a clear solution of the polyester is applied to press plates and also to mahogany-surfaced plywood bonded with a phenol-formaldehyde resin. The resin film on the plates is placed in contact with the coated plywood, the assembly hot-pressed, and the plates removed ; (8) a solution of the polyester containing lauroyl peroxide and titanium dioxide is sprayed on stainless steel plates and precured. The film is transferred to a cork sheet, interposing a sheet of paper impregnated with phenol-aldehyde resin, by hot-pressing.