Patent GB-650923-A (GB)
Title: Improvements in or relating to the production of coloured filaments or fibres of polyethylene terephthalate
IPC: D01F6/62
Filed: 1948-12-03
Abstract: Filaments capable of being coloured by treatment with a diazonium compound are obtained by spinning polyethylene terephthalate which contains dissolved therein an azo coupling component.  For the coupling component there may be used an arylamide of 2 : 3-hydroxynaphthoic acid, e.g. the p-anisidide, and for the diazonium compound there may be used the diazonium derivative of m-nitro-p-anisidine or tetra-azotized dianisidine. A mixture of coupling components may be incorporated in the polymer prior to filament formation and a mixture of diazonium compounds may be used for development of the azo dyestuffs.  The diazonium compound may be formed in situ by impregnating the filaments or fibres with the corresponding amine and then treating with nitrous acid.  The coupling component should be stable at the temperature used in the spinning process and should not cause any marked degradation of the polymer.  In addition to the coupling component, other substances may be incorporated in the molten polymer, e.g. there may be added finely-divided organic or inorganic substances, such as those described in Specification 504,714, for obtaining delustred filaments.  The coupling component may be added in solid form to the molten polymer or in the form of a solution or suspension in a small quantity of polyethylene terephthalate or in some medium which can be removed by evaporation or other means before the spinning process. Alternatively, the coupling component may be added to the solid polymer before melting.  The molten polymer containing the coupling component may be spun directly or it may be cooled, formed into solid chips, rods, or other shapes, and then remelted in the spinning apparatus.  The filaments may be drawn or stretched during or after the process of formation.  The diazonium compound may be applied uniformly so as to obtain an overall colouration of the filamentary products or it may be applied locally, e.g. by printing.  By using different diazonium compounds, a variety of shades can be obtained on filamentary products containing a particular coupling component and multi-coloured patterned effects can be obtained.  In an example, polyethylene terephthalate chips are mixed with 1 per cent of 2-hydroxy-1-naphthoyl-51-chloro-ortho-toluidide and the mixture is dried at 190 DEG  C. under vacuum.  The dry mixture is moulded under heat and pressure to form a thin rod.  The rod is charged into a melt spinning apparatus and the molten polymer is formed into filaments which are subsequently doubled, twisted, and then stretched by passing them round a steel pin heated to 80 DEG  C.  The yarn obtained, which is of a pale yellow colour, is then impregnated with an aqueous dispersion of 4-chlor-2-nitroaniline at 97-100 DEG  C., and then diazotized.  A bright scarlet dyeing is obtained.  In another example, the coupling component which is incorporated in the polymer is 2-hydroxy-3-naphthoyl-p-anisidide, and the amine which is diazotized on the yarn is m-nitro-p-anisidine.  Specifications 375,393, 527,532, 533,307, and 629,452, [Group IV (c)], also are referred to.ALSO:Filaments capable of being coloured by treatment with a diazonium compound are obtained by spinning polyethylene terephthalate which contains dissolved therein an azo coupling component.  For the coupling component there may be used an arylamide of 2 : 3-hydroxynaphthoic acid, e.g. the p-anisidide, and for the diazonium compound there may be used the diazonium derivative of m-nitro-p-anisidine or tetra-azotized dianisidine. A mixture of coupling components may be incorporated in the polymer prior to filament formation and a mixture of diazonium compounds may be used. The diazonium compound may be formed in situ by impregnating the filaments or fibres with the corresponding amine and then treating with nitrous acid.  The diazonium compound may be applied uniformly to the filamentary products or it may be applied locally, e.g. by printing. Multi-coloured patterned effects may be obtained by applying different diazonium compounds to different parts of the filamentary products.  In an example polyethylene terephthalate containing 1 per cent of 2-hydroxy-1-naphthoyl - 51 - chloro - ortho - toluidide is melt-spun and the filaments obtained are doubled, twisted, and stretched.  The yarn is then impregnated with an aqueous dispersion of 4 - chlor - 2 - nitroaniline at 97-100 DEG  C. and then diazotized.  At the same time, the azo dye is formed giving a bright scarlet colour.  In another example, the coupling component which is incorporated in the polymer is 2-hydroxy - 3 - naphthoyl - p - anisidide, and the amine which is diazotized on the yarn is m-nitro-p-anisidine.  Specifications 375,393, 504,714, 527,532, 533,307 and 629,452 are referred to.