| 摘要 |
<PICT:0574621/IV/1> Films or sheets are produced by applying a solution of a cellulose derivative or other filmforming substance from a feeding device to a moving casting surface having a temperature lower than that of the solution, the formation of solvent droplets on the casting surface being prevented or reduced by solvent condensing and collecting means disposed in the vicinity of the line of contact of solution and casting surface. The condensing means may comprise a metal or other condensing surface in the form of a tube or coil through which a cooling medium is passed, the surface being at a temperature lower than that of the casting surface. A trough or other means is adapted to collect and lead away the solvent condensing on the coil or pipe. A film-forming solution is fed in the form of a sheet from a double walled hopper 1 adapted to contain a heating medium, to a moving casting wheel 8. The thickness of the sheet or film is regulated by blades 9 and 10, the blade 10 being adjustable by screw 12. The space between the slot 7 and casting surface 8 is enclosed by baffles 14, 15 and 16. A metal condensing surface comprising a tube 18 disposed along the length of discharge slot 7 is cooled by passing cold water or other cooling medium therethrough. Solvent condensing on tube 18 is collected in trough 19 and led away. In a modification, the baffle 14 is so formed to provide a trough within which the condensing tube 18 is supported. A suitable film-forming solution is cellulose acetate or other organic ester of cellulose in a solvent mixture of propylene dichloride and ethylene dichloride or propylene dichloride and a lower fatty alcohol, e.g. methyl alcohol. Specifications 528,107, 528,375 and 528,382 are referred to. |
