Patent GB-719860-A (GB)
Title: Improvements in the production of artificial filamentary materials
Inventor: FINLAYSON DONALD
IPC: D01F2/28
Filed: 1951-06-12
Abstract: Artificial filaments containing effect materials are obtained by urging a mixture of powdered effect material and powdered filament-forming material against one side of a heated plate having one or more spinning orifices therein so that the filament-forming material is fused by heat supplied from the plate, continually supplying fresh mixture to the plate, and drawing away the mixture of fused material and effect material through the orifice or orifices in the form of a filament or group of filaments.  The effect material may be a white inorganic pigment such as titanium dioxide or barium sulphate, e.g. to obtain low lustre filaments, or it may be powdered glass or silicon carbide powder to obtain products suitable for abrasive purposes, or it may be powdered silica gel.  A coloured organic or inorganic pigment may be used as the effect material, e.g. carbon black, Prussian blue, ultramarine, chrome yellow, ferric oxide, indanthrone or halogen derivatives thereof, flavanthrone, dibenzanthrone, dimethoxy-dibenzanthrone, anthraquinone carbazoles, azo pigments such as azo dyes from diazo compounds and beta-naphthol, acyl acetic arylamides and arylamides of 2.3-hydroxy-naphthoic acid or ortho-hydroxy-carboxylic acids of the anthracene, carbazole, and di-phenylene oxide series, phthalocyanine pigments, acid wool dyes, or water-insoluble dyes having a direct affinity for the filament-forming material.  In the case of nylon or cellulose acetate, the water-insoluble dyes of the azo-, nitro-diarylamine-, or anthraquinone series may be employed.  The proportion of effect material may range from below 0.5 per cent. to 10 per cent. or more of the weight of the filament-forming material.  Mechanical pressure may be applied intermittently to the particles of material on one side of a layer of the mixture in contact with the heated plate so as to urge the mixture against the plate.  A vibrating ram may be used for this purpose.  An atmosphere of inert gas such as nitrogen may be maintained about the powdered material that has been applied to the plate.  Two powders, each containing a different effect material may be fed to the group of orifices, e.g. from opposite sides of the ram. A group of filaments, some of which contain one effect material and some another, may be obtained.  The intensity of colour or other effect may change at intervals along the length of the filaments, or the filaments may exhibit a longitudinal striped appearance due to two different mixtures having passed through a single orifice without intimate co-mingling.  The filament-forming material may be cellulose triacetate or tripropionate, or a partially de-acylated cellulose acetate or propionate, cellulose aceto-propionate or butyrate, ethyl or benzyl cellulose, polyethylene, polystyrene, a polyurethane, polyurea, or polyamide.  Preferably, the powdered air-dry mixture is subjected to a heat treatment in air or vacuum prior to being forwarded to the hot plate containing the spinning orifices. Filaments of fine or coarse denier may be obtained by using orifices of appropriate size or by adjusting the degree of drawing of the freshly formed filaments.  A single orifice in each plate may be used for spinning heavy denier filaments suitable for use as bristles. Narrow bands, ribbons, or straws may be obtained by using a slit-shaped orifice.  Specification 719,853 is referred to.