Patent GB-622109-A (GB)
Title: Polarizing crystalline formation by transfer and expansion
IPC: G02B5/30
Filed: 1946-03-20
Abstract: A supported polarized crystalline film is formed by depositing a crystalline layer from a solution on to a support, the crystalline layer having a multiplicity of cleavage planes, applying an adherent flexible material to the crystalline layer, stripping the adherent material from the crystalline layer whereby a part of the crystalline layer cleaves or splits from the original layer and is carried off by the adherent flexible material and thereafter the original crystalline layer and the separated crystalline layer are subjected to treatment with a supersaturated solution of the crystalline material.  The crystalline layer may be iodoquinine sulphate or iodocinchonidine sulphate and may be deposited on to the support according to the methods of Specifications 450,090 and <PICT:0622109/III/1> <PICT:0622109/III/2> 545,185.  The support may be flexible or rigid or semi-rigid and may be glass, hard styrol, urea - formaldehyde resin, cellulose acetate, plasticized polystyrene.  The adherent flexible material may be a synthetic resin or a cellulose derivative and may be applied to the crystalline layer as a preformed film or as a solvent solution and the solvent subsequently removed.  The preformed film may be laminated, for example, a sheet of cellulose nitrate united to a sheet of polystyrene.  The adherent material has preferably a refractive index matching that of the crystalline layer.  Optionally, the supported polarized crystalline film may, before treatment with a supersaturated solution, be expanded by stretching, using a solvent such as benzol, or toluol and/or heat. In Fig. 19 is shown one form of apparatus for continuously carrying out the process using as the adherent material a preformed film.  A transparent rotating drum 240 has on its surface a polarizing crystalline material 241 which is constantly renewed with supersaturated solution 242 in transparent tank 243. The thickness of the polarized crystalline layer is dependent upon the speed of rotation of the drum which is controlled by photo-electric apparatus 246.  The built up crystalline layer dried by blotter roller 248, contacts roller 249 which holds a pool of laminating oil 250.  The polarizing crystalline layer 241 coated with oil then passes in contact with a preformed laminated polystyrene film 252 delivered by roll 253 which is pressed into contact with the layer 241 by rolls 254, 256, 257.  Heating means 255 and cooling means 258 assist the lamination.  The cleavage is effected under roller 260 in the presence of a liquid 261.  The film 252 with the attached crystalline layer then travels through a heated oven 259 and is expanded both longitudinally and laterally, cooled at 269 and built up to the desired thickness by passing the film through a supersaturated solution 270.  The thickness is controlled by a photo-electric device 272.  The built up polarized crystalline film is then turned at the point 280 and laminated with a protecting film 281 before being wound on a storage roll.  The splitting or cleavage may be effected below a liquid.  The liquid may be a supersaturated solution of the crystal layer.  A method of constantly providing a supersaturated intensification solution is shown in Fig. 28. Directed through supersaturated solution 410 is a light beam 411 from a source 412, the formation of crystals 413 in this solution leads to reflection of the light beam as a diverging beam 415 which when picked up by photo-electric cell 416 causes a cyclic movement of all flasks, flask 410 being replaced by flask 417 containing fresh supersaturated solution 418.  The flask 410 is moved to position 419 and the contents emptied into container 420 which is maintained at a temperature sufficiently high to dissolve all crystalline material entering the container.  The liquid from the container 420 is transferred by pump to container 425 where the liquid is cooled by a thermostatic control device 428 until it is at the incipient supersaturation point.  Flask 419 is moved to position 431 where it is cleaned, flask 431 is moved to 434 and dried, whilst flask 434 is moved to 417 where it is filled with liquid from container 425 and the liquid cooled to the supersaturation point.  The supersaturated solution may be applied to the supported crystalline film to be intensified by using an apparatus which includes a rocker device and also a device for discharging the applied supersaturated solution from the crystalline film surface.ALSO:A film made from a mixture of polystyrene and coumarone-indene resins is plasticized with beta-methyl naphthalene and menthyl cinnamate by applying an oil to the film comprising these ingredients.  Specifications 450,090 and 545,185, [Group III], are referred to.