Patent GB-551179-A (GB)
Title: Improvements in and relating to the preparation of reinforced sheet material
IPC: B29C67/24
Filed: 1941-05-09
Abstract: 551,179. Coating webs; coated fabrics. BRITISH ARTIFICIAL RESIN CO., Ltd., and FRANK, F. May 9, 1941, No. 6044, [Class 140] Reinforced sheet material especially for use as a glass substitute is made from aqueous dispersions of natural or artificial rubber or partially condensed or polymerized synthetic resins by passing a fabric of wire or textile material, e.g. of silk, cotton, wool or glass fibres through the dispersion which in contact with one side of a support of porous material, removing the aqueous liquid by reduction of pressure on the other side of the support and drying and curing or vulcanizing the material. In a modification the dispersionis flowed on to the fabric between a lip and the porous support. The product may be dusted with French chalk, talcum, lycopodium, potato flour or rice starch before rolling up or may be coated with a cellulose derivative or resin, e.g. polyvinyl resin varnish which may contain umbelliferon esters or reduce the decomposing effect of ultra violet rays. The fabrics may be pre-tested with wetting agents. The coating may be made porous by incorporating in the dispersions substances such as ammonium carbonate and sodium bicarbonate which evolve gas on heating or alkali and alkaline earth salts which may be washed out with water to form pores. Fabric from a roll 19 is wetted in a tank 20 and passed over a roller 22 on to a filter cylinder e provided with tiles n of porous material, e.g. porcelain, sintered glass, plaster of Paris, cement, porous ebonite, wood, glass fabric or fabric impregnated with resins. The lower part of the cylinder dips into a trough 10 fed with aqueous dispersion from an overhead supply tank, the level being floatcontrolled. The porous periphery of the cylinder is connected by inwardly and laterally extending ducts to a cut-off valve box 1, Fig. 4, through ports z. A dividing web 3 in the valvebox affords two chambers connected to a suction pipe 4 and to the atmosphere at 6 respectively. If desired three chambers may be provided as indicated at A, B, C, Fig. 1, so that dry steam, a washing liquid or low-pressure air may be supplied after suction has been applied. The fabric remains in contact with the cylinder until it is stripped off by a doctor knife 23, whence it passes over rollers 13<SP>1</SP> in a drying tunnel 26, is calendered and wound into a roll. After stripping, the rubber disperson may be coagulated by passage of the fabric over an absorbent material saturated with acetic acid, or a solution of aluminium sulphate or alum. Suction is applied to the fabric before, during and after its entry into the dispersion. The pores of the cylinder may be washed by replacing a dispersion by water, acid or lye. As shown in Fig. 6 the coated fabric may be dried by an arcuate drying jacket 30 and washed by spraying water from pipes 32 before final drying. The rubbercoated fabric may be vulcanized by passage through hot water. Partially condensed or polymerized synthetic resins may be cured by 'hot air while the fabric is on the cylinder or, after removal therefrom, by hot water. The material may be removed from the drum in uncured state, a number of layers superposed and cured to form laminated material. The product may have one plane and one undulating face due to the coating being drawn into the fabric by suction.