| 摘要 |
315,840. Celluloid Corporation, (Assignees of Walsh, J. F., Stevens, J. H., Flynn, K., Caprio, A. F., and Alcorn, T, E.). July 19, 1928, [Convention date]. Casting-apparatus; celluloid. - Continuous sheets or films are prepared by spreading a solution of the sheet forming material, for example a. solution of cellulose or one or more cellulose derivatives such as pyroxylin, cellulose acetate, viscose or ethyl cellulose in any suitable solvent, on to the surface of a moving inert liquid medium, for example mercury or a low melting alloy, evaporating the solvent from the deposited solution and stripping the more or less dried sheet or film from the surface of the liquid medium. Low melting alloys comprising for example lead, tin, bismuth and cadmium, may also be used. In the apparatus shown, mercury 3 is fed into the trough 1, provided with baffle plates 2 arranged along its base and sides, through the inlet 4. The trough is elevated at the inlet end so that the mercury flows toward the outlet or outlets 5 in the end plate 6 and is drawn off through an overflow pipe or pipes 7 to an overflow tank 8, from whence it is recirculated through the conduit 9 and pump 10 to the inlet 4. A hopper 11 is provided with a gate 14 manipulated by lever arrangements 15 in order to vary the width of the opening 13 through which the solution 12 is delivered in the form of a sheet 16 on to the surface of the liquid medium from which it. is removed by the stripper roller 18 and passed to the drying drum 19 and winding spool or drum 20. One or more drying rolls may be used and the film may pass over several rolls 18 before passing to such drying rolls. The trough 1 is provided with a compartment 17 in which heating means may be installed or through which a heating liquid may be passed. The thickness of the film or sheet may be varied by controlling the speed of travel of the liquid medium as well as by varying the thickness of the sheet of solution issuing from the hopper. Submerged propeliing devices may be used if desired to accelerate the flow of the liquid medium. A suitable length for the mercury bath is 45 feet, in which case the length of sheet or film immersed in the bath is about 40 feet, and a suitable width 28 inches, in which case the width of the film is 22 inches. The preparation of a cellulose acetate film approximately 0.005 inches thick by employing a mercury bed travelling at 120 feet per hour in such a trough is described. The baffles are preferably spaced about 1 foot apart. The mercury may be carried forward on a travelling belt suitably sectioned to hold the mercury level until it passes the stripping point, and also provided with sides to retain the mercury or any other means may be employed for causing the liquid medium to flow. |
