Patent GB-570880-A (GB)
Title: Improvements in textile fabrics consisting of or containing cellulose ester fibres
IPC: D06M11/38
Filed: 1943-09-24
Abstract: Textile fabrics consisting of or containin cellulose ester fibres are saponified substantially on one side only so that they may be dyed to produce fabrics of which the two sides are coloured differently.  The saponifying agent, which may be an aqueous solution of an alkali metal hydroxide or carbonate thickened with water-soluble gums such as gum tragacanth, and/or water-insoluble inorganic substances such as french chalk, fuller's earth, and kaolin, is applied to one side of the fabric, and saponification is assisted, if desired, by heating the material.  Preferably, a mechanical or chemical resist is previously applied to the side of the material to remain substantially unsaponified.  Suitable resists are water-soluble gums, such as gum gatto, fats or waxes, or a solid water-insoluble acid, particularly a higher fatty acid such as stearic or palmitic acid. The acid may be used in conjunction with a water repellent wax such as paraffin wax, and it may be applied to the material as a solution in a volatile liquid such as a chlorinated hydrocarbon and the liquid subsequently removed by evaporation.  Alternatively, the acid may be applied as its ammonium salt and the material heated to expel ammonia.  The acid resist may be applied to both sides of the fabric. Treating with the resist and/or the saponifying agent may be local. After saponification, the fabric is treated with dilute hydrochloric acid or other aqueous acid to neutralize the saponifying agent, and finally washed.  The treated fabric may then be dyed, printed or discharge printed with dyes having widely differing affinities for cellulose and the cellulose ester to produce a coloured effect on one side of the material differing from that on the other.  The two types of dyestuffs, e.g. a direct cotton dye and a water-insoluble cellulose acetate dye may be applied together or separately. Alternatively, dyes or dye components may be applied together with the saponifying agent. Vat dyes in leuco form or as sulphuric esters of the leuco compound, e.g. Soledon Jade Green XS or Indigosol O may be applied to and converted on the saponified portion of the material.  Enolic coupling components having affinity for cellulose, e.g. arylamides of 2 : 3-hydroxynapthoic acid or other orthohydroxy carboxylic acid or arylamides of aceto-acetic or other b -keto-carboxylic acid may be applied to and developed to azo dyes on the material, and, if desired, diazo compounds may be applied with the coupling component.  In the examples, cellulose acetate fabric is padded in an aqueous solution of gum gatto or ammonium stearate or a solution of stearic acid in perchlorethylene and dried.  The material is back-filled with a paste of gum tragacanth, caustic soda and french chalk, dried, treated with dilute hydrochloric acid, washed and dyed.  The dye bath may contain a mixture of 2 : 4-dinitro-41-amino - diphenylamine, 1 - amino - 4 - hydroxy - anthraquinone, Durazol Fast Yellow B400 and Durazol Fast Blue 4G200 or a mixture of 2 : 4-dinitro - 41-amino - diphenylamine, 1 - amino - 4 - hydroxyanthraquinone, 1 - methylamino - 4 - (b -hydroxyethylamino) - anthraquinone, Durazol Fast Yellow B400, Chlorazol Brown MS and Chlorantine Fast Blue GLL200.