Improvements in the manufacture of films, foils, and the like and apparatus for use in such manufacture

摘要

Films, foils, and like products are obtained by evaporating a volatile solvent from a layer of film-forming dope on a travelling support and a colouring-agent or other desired constituent of the product is introduced into the partly dried layer of dope by causing a solution of said constituent to flow, drip, or be sprayed on to the surface of said layer from supplying means kept out of contact with the surface. Coloured foils of cellulose acetate are produced by extruding the acetate solution in acetone on to an endless nickel band passing through a warm atmosphere and causing to flow on to the surface of the foil just beyond the point of extrusion a solution of a dye in acetone, or alcohol, and containing a plasticizer such as dimethyl phthalate. The dye may be methylene blue, malachite green, 1-4 di(methylamino) anthraquinone, or 4-nitro-2-methoxy benzene azo dimethyl aniline. The device for applying colouring or other liquid may comprise a reservoir for the liquid with adjustable aperture, a wick or curtain of porous material for causing flow of liquid from the reservoir to the surface of the film, the wick extending downwardly through the aperture, means for varying the aperture to control the amount of liquid passing through the wick, and means for micrometrically adjusting the height of the lower edge of the curtain above the surface of the film. As shown in Fig. 1, the endless band 10 passes the extrusion device 13 from which film-forming solution is extruded on to the band. It then passes the liquid-applying device 14. As shown in Figs. 2 and 4, the liquid applying device is of V-shaped section and has a fixed side 15 and fixed ends carried by brackets 17 and micrometer screws 18 resting on fixed brackets 19. The other side 26 of the trough is pivotally mounted on a bolt 27. An extension 28 of the side 26 functions as a crank to move the side about its pivot 27 so varying the side of the aperture between the sides of the trough. The adjustment of the aperture is made by turning the head 35 of the micrometer screw 31. A curtain 37 comprising a foraminous base wound with layers of flannel extends from the trough downwardly towards the film-forming band. In operation the curtain is first brought into contact with the freshly extruded layer of film 41 and the screws 18 are then altered so as to bring the curtain itself but not the stream of liquid oozing therefrom out of contact with the film. The wick may extend across the whole surface of the band for uniform colouring. Local colouring may be effected and two or more liquid applying devices in line or staggered relationship may be provided. Other liquid applying devices may be used and the liquid may be sprayed or dripped. The feed to the liquid-applying device may be by gravity or pump. Instead of colouring matters, plasticizers and non-inflammators may be applied to films in the same manner.