Patent GB-1076011-A (GB)
Title: Improvements in or relating to the production of surfaced sheet material
Inventor: BOTTLE EDWARD
IPC: B05D1/36
Filed: 1964-04-02
Abstract: 1,076,011. Coatings; coating apparatus. WIGGINS TEAPE RESEARCH & DEVELOPMENT Ltd. Jan. 18, 1965 [April 2, 1964], No. 13688/64. Headings B2K and B2L. Rigid sheet material or material held in masking frames is surfaced by disposing finely divided substantially dry thermosetting synthetic resin in a distributor and while moving the sheet material beneath the distributor effecting therefrom a substantially even distribution of resin over the surface of the sheet, subjecting the resin-surfaced sheet to heat at a temperature sufficient to cause the resin to adhere to the sheet and form thereon a substantially continuous film covering the sheet, cooling the heated resin-surfaced sheet, and effecting consolidation of the film in a platen press. A pigment or pigments may be mixed with the dry synthetic resin prior to delivery thereof to the distributor. Finely divided substantially dry thermosetting synthetic resin may be disposed in first and second resin distributors and finely divided substantially dry pigment or pigments in a pigment distributor and while moving the sheet material progressively beneath the distributors, a substantially even distribution of resin is effected over the surface of the sheet, of pigment over the resin-surfaced sheet and of resin over the resin/pigment surfaced sheet, the resin/pigment/resin surfaced sheet is heated at a temperature sufficient to cause the surfacing to adhere to the sheet and form thereon substantially continuous films covering the surface of the sheet, cooling the surfaced sheet and effecting consolidation of the films in a platen press. The heating may be effected by radiant heat directed towards the surfaced sheet from above the path thereof. The resin may be spray-dried melamine-formaldehyde or powdered phenol-formaldehyde. The sheet material may be plywood, hardboard, asbestos cement sheets, asbestos insulating boards, or paper laminates, which may be patterned or printed before application of the resin. Apparatus for surfacing rigid sheet material or sheet material held in masking frames comprises a conveyor e.g. a wire conveyor, 1, on which the material is placed either manually or automatically, first and second resin distributors 2, 3 and a pigment distributor 4 between distributors 2, 3 as spaced along the upper run of the conveyor. The distributors which are fed by hoppers 5, 6 and 7 effect substantially even distribution of resin and pigment over the sheet material as the material is carried by the conveyor. The distributors may reciprocate in a direction at right angles to the direction of movement of the conveyor. The sheet material bearing superposed layers of resin, pigment and resin respectively is moved through heater means, which may comprise infra-red radiant heater elements 8 mounted in reflector housing 9, where the resin is caused to adhere to the sheet material and form a substantially continuous film thereon. The sheet material is then cooled e.g. by an air blower, either on or after removal from the conveyor, prior to the consolidation of the coating e.g. by platen press, to render the coating non porous and impermeable to air and water. Excess coating material may be removed from the conveyor by passage around roller 11 which is rotatable in a bath 13 containing a solvent for the resin. The pigment may be omitted in which event distributors 3, 4 and hoppers 6, 7 may be omitted. Distributors 3, 4 and hoppers 6, 7 may be omitted, and a pigment-resin mixture distributed by distributor 2.