Patent GB-727801-A (GB)
Title: Improvements in or relating to resinous compositions
Inventor: DEUTSCH FRANZ SAM
IPC: B44F9/08
Filed: 1952-01-30
Abstract: A resinous composition having a pearlescent appearance comprises 1 to 20 per cent by weight of bismuth oxysalicylate incorporated in a resinous cellulose derivative or a polystyrene resin, or 0.1 to 10 per cent of bismuth oxycarbonate incorporated in a polystyrene resin, or 1 to 5 per cent of bismuth oxycarbonate incorporated in a phenol-formaldehyde resin.  The bismuth salt may be incorporated in the resinous material while the latter is in the solid state, and in that case a modified composition may be obtained by incorporating 0.1 to 10 per cent of bismuth oxycarbonate with a cellulose derivative. The cellulose derivative may be cellulose acetate, e.g. having an acetyl content, calculated as acetic acid, of 50-60 per cent, cellulose propionate, cellulose aceto-butyrate, e.g. having a butyryl content (as butyric acid) of 36-37 per cent and an acetyl content (as acetic acid) of 13-14 per cent, or ethyl cellulose, e.g. having an ethoxyl content of 42-50 per cent.  The polystyrene resin may be a polymer of styrene itself or of alpha-methyl styrene or of a chlorine, methyl or ethyl nuclear substituted derivative thereof, or a copolymer of these substances.  The phenol-formaldehyde resin may be a condensation product of formaldehyde with phenol, cresol, xylenol, resorcinol, or other mono-, or di-hydroxy phenol.  It is preferably used in a light-stable form.  The bismuth salt may be incorporated by working it into a portion of the plastic resinous material on hot rolls, and sheeting and grinding the mixture and mixing it with the remainder of the resinous material which has also been sheeted and ground.  Articles such as sheets, films, coatings, rods, plates, filaments, dishes and ashtrays, may be obtained from the compositions by injection, compression or transfer moulding or by casting.  In an example, cellulose acetate flakes are mixed with about 7 per cent of bismuth oxysalicylate and about 38 per cent of dimethyl phthalate in a heated roller mill and the mixture is sheeted and ground.  It is then mixed with about a third of its weight of a powder formed from cellulose acetate containing about 55 per cent of dimethyl phthalate but no bismuth salt.  The mixture is injection-moulded.  In another example, polystyrene (molecular weight 200,000) is mixed with about 1 per cent of bismuth oxycarbonate and coloured with a mixture of Rhodamine 6G and Acetone Brown.  The mixing is effected in a heated screw extruder and the mixture is formed into thin rods of square cross-section.  These are cut into granules and formed into a moulding powder.  In another example a moulding powder comprising polystyrene (M.W. 200,000) with 20 per cent of bismuth oxysalicylate is mixed with two-thirds of its weight of a moulding powder of a softer grade of polystyrene (M.W. 80,000) and the blend is injection-moulded.  In another example, a resin is produced by condensing commercial cresylic acid (containing about 50 per cent of meta-cresol) with formalin solution in presence of ammonia.  The liquid resin is dehydrated by vacuum distillation. The resin is milled with 1 per cent of oleic acid and 1-5 per cent of bismuth oxycarbonate on heated rolls and then cooled and ground to form a moulding powder.