Patent GB-489467-A (GB)
Title: Improvements in or relating to the production of articles containing plastic materials
IPC: C08L1/12
Filed: 1937-10-13
Abstract: Moulded articles showing mottled or variegated effects are produced by moulding under the action of heat and pressure a mixture of two or more chemically different materials which are mouldable under heat and pressure and which have different degrees of plasticity under the moulding conditions employed, at least one of the plastic materials containing an effect material different from the effect material, if any, in the other or another of the plastic materials used.  The effect material may be a dye or pigment, or a material which produces a difference of lustre, e.g. pearl essence.  Specified plastic materials are cellulose derivatives, e.g. nitrocellulose, cellulose acetate, formate, propionate or butyrate, and ethyl-, methyl- or benzyl-cellulose, polymerized vinyl derivatives, e.g. polyvinyl acetals, polymerized vinyl acetate, vinyl ethinyl carbinol, vinyl chloracetate or the esters, nitrites or amides of acrylic or alkacrylic acid, and interpolymers of vinyl acetate and chloride, phenol-formaldehyde resins, urea formaldehyde resins, glycerolphthalic anhydride resins, toluene - sulphonamide-aldehyde resins, and coumarone resins.  The plastic materials may contain plasticizers, e.g. the aryl sulphonamides such as p-toluene ethyl sulphonamide, di-alkyl phthates such as dimethyl- and dibutyl - phthalate, dialkyl tartrates such as dibutyl tartrate, the alkoxy alkyl esters of polybasic organic acids such as di - b  - ethoxyethyl- and di-b -methoxyethylphthalate, the polybasic acid esters of the monoalkyl ethers of polyhydric alcohols such as the diethylene glycol ethyl ether ester of phthalic acid, alkyl and aryl esters of phosphoric acid such as triethylene glycol phosphate, tricresyl phosphate, di-ethyl-mono-cresyl phosphate and mono-methyl-di-phenyl phosphate, camphor, glycol dihexoate, benzyl benzoate, acetanilide, butyl glycollate and castor oil.  The effect material may be worked into the plastic material on malaxating rolls, or may be applied in a solvent which does not substantially dissolve or attack the plastic material, e.g. polyvinyl resins in the form of chips may be treated with a solution of colouring matter in aqueous acetone or carbon tetrachloride.  The mixtures of plastic materials may be formed into articles such as spectacle frames, fountain pen barrels, combs, or knobs for wireless apparatus having the appearance of tortoise shell, pearl, onyx or marble, by injection, stuffing or pressure moulding processes.  Examples of moulding compositions comprising components A and B are (1) (A) polyvinyl acetal and di-b -methoxyethyl phthalate admixed with (B) coloured cellulose acetate and di - b  - methoxy - ethyl phthalate with or without polyvinyl acetal; (2) (A) polystyrol admixed with (B) a coloured mixture of cellulose acetate, toluene sulphonamide-formaldehyde resin and a plasticizer; and (3) (A) tricresyl phosphate and an interpolymer of vinyl chloride and acetate coloured pearl with a nacreous pigment such as aluminium, mercurous chloride or fish scale, admixed with (B) a mixture of polyvinyl acetal, coumarone resin, calcium stearate and cresol-acetaldehyde resin.  In these examples, polyvinyl acetate or polystyrol may replace the polyvinyl acetal and other cellulose derivatives may replace the cellulose acetate.