GB306351A - Improvements in or relating to the manufacture of unsplinterable glass - Google Patents

Abstract

306,351. Robertson, J. H. June 25, 1928. Compound transparent sheets.-To secure firm adhesion between the glass and celluloid sheets forming non-splintering transparencies, the glass is first coated with a cement consisting of a gelatinous silicate in a hot solution of gelatine with or without potassium chrome alum. or of albumen, or of casein. The coated face is dried and a celluloid sheet of about 0.005 inch thickness, softened with an acid such as propionic acid is secured thereto, or alternatively, a solution of 1 gram celluloid, 30 ccs. amylacetate, and 4 cos. propionic acid may be applied thereto. Two sheets formed by this process are then joined to a sheet of celluloid by immersing them in a bath of propyl alcohol and gently pressing them together. If treated with potassium chrome alum, the gelatine solution is prepared by adding gradually 100 parts of a boiling solution of 0.2.5 per cent chrome alum to 100 parts of a boiling solution of 4 per cent agar-agar or gelatine and maintaining the resultant solution at 95‹ C. for half an hour, then filtering through cotton wool and mixing hot with the gelatinous silicate solution. Casein when used is preferably dissolved in strong sodium silicate solution which is then diluted and filtered and applied to the glass cold. When dry, this coating may be treated with a solution of casein in ammonia to provide a surface which will amalgamate with the celluloid layer. Drawn glass is preferably used and it is cleaned with nitric acid and distilled water. The edges of the finished sheets are sealed with casein, resinous bodies, silicates, gutta percha. &c., or with the product obtained by precipitating meta styrene with acetone in benzene solution and treating the precipitate with tri-cresyl phosphate.