Patent GB-895507-A (GB)
Abstract: 895,507. Coated fabrics; coating webs; laminates and laminating. INTERNATIONAL POLAROID CORPORATION. March 4, 1959 [March 27, 1958], No. 7577/59. Class 140. [Also in Group XX] A sheet material, adapted to be rendered light-polarizing when exposed to a solution containing a dichroic substance, is prepared by applying a coating of a solution of a plastic material which on hardening will form a molecularly orientatable layer, to a transparent supporting layer, hardening the solution, then stretching the supporting layer and hardened coating as a unit to molecularly orientate at least the coating. As shown in Fig. 2, the stretched material 12 comprises supporting layer 16 which may be formed of a hydroxylcontaining vinyl polymer, e.g. a partially hydrolysed polyvinyl ester such as polyvinyl acetate, polyvinyl alcohol or a derivative thereof such as polyvinyl acetal, or rubber hydrochloride, and a coating 14 which may be formed from a solution comprising polyvinyl alcohol and possibly a basic nitrogen-containing compound or polymer, e.g. an amino acetal of polyvinyl alcohol, a polyvinyl pyridine quaternary ammonium salt, a #-diethylamino-ethyl methacrylate polymer, deacetylated chitin, or methyl iodide quaternary salt of para-dimethylaminobenzaldehyde, and a cross-linking agent, e.g. boric acid, glyoxal, diphenyl diisocyanate or dimethylol urea. As shown in Fig. 3, the stretched material 12 may be bonded, for example with an aqueous solution of chromic nitrate, to a dimensionally stable base layer 22 which may comprise cellulose triacetate or cellulose acetate butyrate. The coating may be treated with a solution of at least one dichroic direct cotton dye, examples of which are given, which may be distributed uniformly through the coating or may be applied from a printing matrix to provide an imagewise distribution in the coating. A plurality of dichroic direct cotton dyes of different colours may be applied from a printing matrix or printing matrices to provide a multicolour image. As shown in Fig. 4, a composite light polarizing print 26 comprises a dimensionally stable base layer 36, each surface of which has a sheet material 32, 34 which may be as shown in Figs. 2 or 3, produced as described, bonded thereto such that the direction of orientation shown by double-headed arrow 38 of one coating is disposed substantially at 90 degrees to that of the other shown by doubleheaded arrow 40, and the image 28, 30 in each layer is in registered relation for stereoscopic viewing. Alternatively, the base layer 36 may be omitted. As shown in Fig. 5, supporting layer 42 is fed to moving belt 44 and coated with liquid 46 from container 48 to a thickness, governed by wire-wound coating rod 50, which is dried in forced-air heater 52. The coated film is stretched by passage through differentially rotating pairs of rolls 54, 56 and then through oven 58. The stretched film is laminated to base film 60 by means of laminating liquid 62 from container 64 and passage through pressure rolls 66. The laminate is hardened by heaters 68 and a dichroic direct cotton dye 70 is applied to the coating from tank 72, passed through heaters 74 and 76 and taken up on roll 78, a layer of non-adhering paper 80 being employed to separate each turn of the film. The dichroic dye might alternatively be included in the coating liquid.