| 摘要 |
512,967. Cellulose derivative films. KODAK, Ltd. March 26, 1938, No. 9301. Convention date, March 26, 1937. [Class 2 (ii)] Cellulose derivative sheet or film having uniform shrinkage properties and suitable for use in. aerial photography, is produced by depositing in the form of a film on a filmforming surface a solution of a cellulose derivative in a volatile solvent, removing solvent until the sheet is hard enough to be stripped from the surface without undue elongation, curing out residual solvent, and finally subjecting the sheet to annealing treatment in hot water to remove internal strains. Throughout the process excessive longitudinal tension is avoided ; thus, for example, the film may be deposited on a polished drum and various expedients may be employed to facilitate ease of stripping. Any subbing or backing treatments are applied in the curing section and while the film is passing over the driers. In the figure, hopper 8 supplies a thin layer of cellulose derivative solution to the surface of wheel 1, the formed film leaving the wheel at the stripping roll 23 and passing into the curing chamber 11. Subbing or backing solutions are applied to the film from the troughs 49 and 50. After leaving the curing chamber 11, the film passes through the water box 25 where it meets a counter current of hot water of progressively increasing temperature, and then through a further curing chamber 39 to a wind-up 47. The film may pass through more than one water box and, before reaching the water box, it may pass through a number of curing chambers. Examples are given of the. preparation of cellulose nitrate and cellulose acetate-propionate film. Specifications 287,880, [Class 2 (iii)], and 480,645 are referred to. |
