Patent GB-573228-A (GB)
Title: Improvements relating to reinforced glass-substitutes
Filed: 1943-10-26
Abstract: 573,228. Coated fabrics. MOSS, W.H. Oct. 26, 1943, No. 17680. [Class 140] [Also in Group X] A reinforced glass substitute is produced by doping an openwork structure with a hot solution of a thermoplastic cellulose derivative in a liquid which is not a solvent therefor at ordinary temperatures, cooling to convert the applied solution to a gel and stiffening the gel by evaporation of the liquid or a volatile constituent of it. The base structure may be leno or plain woven, knitted or netted textile such as cotton, woven or netted wire fabric such as iron or steel which may be galvanised or tinned, brass copper or other non-ferrous metal; expanded metal or thin perforated metallic sheets. Textile fabric, if used, may be stiffened to facilitate the doping by a pretreatment with gelatin, gum or a water soluble cellulose ether size. The cellulose derivative which forms the basis of the dope may be present in concentration of 50 per cent. or more and may be a simple ester such as cellulose nitrate. acetate propionate or butyrate; as mixed fatty ester such as cellulose acetatepropionate, acetate-butyrate; acetate-stearate; a mixed ester containing the radicles of acetic acid and another carboxylic acid, especially one containing at least 12 carbon atoms, such as cellulose acetate-laurate; or may be an ether of cellulose such as benzyl or ethyl-hexyl cellulose; an ethyl-ester such as ethyl cellulose acetate, ethyl cellulose butyrate or ethyl cellulose stearate. Four kinds of solvent liquid may be used to form the dope. (1) A liquid which is not itself a solvent for the cellulose derivative even at its boiling point such as a monohydric alcohol with not more than 3 carbon atoms, e.g., methanol, ethanol or isopropanol in conjuction with a solvent plasticizer such as dimethyl phthalate, trichlorethyl phosphate, diethyl phthalate, di-(methoxy-ethyl) phthalate, methyl-(methoxy-ethyl) phthalate, ethyl-(ethoxy-ethyl) phthalate, methyl-phthallylethyl glycollate or diethyl tartrate. (2) A mixture of two volatile liquids which together dissolve the celluose derivatives when hot but form a gel on cooling such as an associated liquid which may be propanol or isopropanol together with a non-associated liquid such as a chlorinated aliphatic hydrocarbon for example ethylene dichloride, trichlorethylene, ethylene tetrachloride or propylene dichloride. Solvent plasticizers as specified above or non solvent plasticizers such as triphenyl, tricresyl or tributyl phosphate may be incorporated. (3) A single liquid which is a solvent for the cellulose derivative when hot but forms a gel on cooling such as ethyl acetate, methyl ethyl-ketone, benzene, diacetone alcohol, butyl acetate or toluene. Plasticizers, as above, may be incorporated. (4) A true solvent for the cellulose derivative, such as acetone diluted with benzene or with benzene and ethanol to a point at which the mixture is no longer a solvent at ordinary temperatures. The dopes may be clear or may contain pigments, metallic powders or carbon black and may contain substances protective against ultra violet radiation, such as salol, Michler's ketone, fluoranthene or benzal aceto-phenone. The dope may be applied by brushing, dipping. flowing or by drawing the openwork material through a bath of hot dope, cooling to set the gel and drying at ordinary or elevated temperatures. Specific examples embodying the above materials are given. The Provisional Specification indicates additional uses for the product, such as aircraft construction or auxiliary fuel tanks. Specification 548,632 is referred to.