Patent GB-964149-A (GB)
Title: Improvements in the bleaching of cellulosic fibres
IPC: D06L3/08
Filed: 1962-04-10
Abstract: An aqueous acidified chlorite solution suitable for bleaching cellulosic fibres has a pH of 2-7 and comprises 0.1-3% by weight of a water soluble chlorite, e.g. lithium, sodium, potassium, calcium, barium and strontium chlorites, and 0.001-3% by weight of a water-soluble hydrazine salt.  Suitable hydrazine salts are mono- or di-hydrazine sulphate, mono or dihydrazine phosphate, hydrazine mono- or di-hydrochloride, mono- or di-hydrobromide, mono- or di-hydroiodide, nitrate, borate, carbazimate, formate, acetate, propionate, acrylate, crotonate or propiolate, mono- or di-hydrazine oxalate, malonate, succinate, gluterate, maleate or fumarate, mono, di- or tri-hydrazine propane-1,2,3-tricarboxylate or citrate, hydrazine methyl sulphonate, ethyl sulphonate, propyl sulphonate, mono-, di- or tri-chloroacetate, glycolate, lactate, 2-hydroxy propionate, mono- or dimalate, mono- or ditartrate, aminoacetate, 1-amino propionate, 1-amino-iso-valerate, benzene sulphonate, toluene sulphonate, p-halobenzene sulphonate, benzoate, o-, m- or p-chlorobenzoate, o-, m- or p-nitrobenzoate, salicylate, phenyl acetate, cinnamate, o-hydroxycinnamate, naphthoate, naphthalene sulphonate, naphthenate or hexahydro benzoate, mono- or dihydrazine benzene disulphonate, di- or tri-hydrazine benzene trisulphonate, mono- or dihydrazine phthalate, isophthalate or terephthalate, mono-, di- or trihydroxy alkyl substituted hydrazine salts, monodi- or trialkyl substituted hydrazine salts, monoaryl substituted hydrazine salts and mixed alkyl-aryl substituted hydrazine salts.  The solution which may be acidified by the addition of formic, acetic, hydrochloric, sulphuric, phosphoric or nitric acid, may also contain buffers, e.g. sodium phosphate and sodium acetate, wetting agents, e.g. salts of acyl alkyl taurides, corrosion inhibitors, e.g. water-soluble nitrate salts, and chelating agents, e.g. amines having a plurality of hydrogen atoms of the amino group replaced by fatty carboxylic acid groups.ALSO:Cellulosic textile fibres, e.g. cotton, linen, jute, hemp and regenerated cellulose, alone or blended with nylon, polyester or polyacrylonitrile fibres, are bleached by wetting them to a pickup of 50-120% by weight with an acidified, aqueous chlorite solution having a pH of 2-7 and comprising 0.1-3% by weight of a water soluble chlorite, e.g. lithium, sodium, potassium, calcium, barium and strontium chlorites, and 0.001-3% by weight of a water soluble hydrazine salt, holding them at a temperature of 20 DEG -130 DEG C. for 0.25-4 hours, preferably by steaming, and rinsing in water.  In a modification of the process of the fibres are wetted with an acidified, aqueous solution having a pH of 2-7 comprising 0.1-3% by weight of water soluble chlorite to apply to the fibrous material 0.1-3% by weight of the chlorite and are then wetted with an aqueous solution comprising 0.001-3% by weight of a water soluble hydrazine salt to apply 1-100% of the hydrazine salt to the fibrous material based on the weight of the chlorite and are then held at a temperature of 20 DEG -130 DEG C. for 0.25-4 hours before rinsing in water.  Suitable hydrazine salts are mono-or di-hydrazine sulphate, mono or dihydrazine phosphate, hydrazine mono- or di-hydrochloride, mono- or di-hydrobromide, mono- or di-hydroiodide, nitrate, borate, formate, acetate, propionate, acrylate, crotonate or propiolate, mono- or di-hydrazine oxalate, malonate, succinate, glutarate, maleate or fumarate, mono-, di- or trihydrazine propane-1, 2, 3-tricarboxylate or citrate, hydrazine methyl sulphonate, ethyl sulphonate, propyl sulphonate, mono-, di or trichloroacetate, glycolate, lactate, 2-hydroxy propionate, mono- or dimalate, mono- or di-tartrate, aminoacetate, 1-aminopropionate, 1 aminoisovalerate, benzene sulphonate, toluene sulphonate, p-halobenzene sulphonate, benzoate, o-, m- or p chlorobenzoate, o, m or p nitrobenzoate, salicylate, phenyl acetate, cinnamate, o-hydroxycinnamate, naphthoate, naphthalene sulphonate, naphthenate or hexahydrobenzoate, mono-or dihydrazine benzene disulphonate, di- or tri hydrazine benzene tri-sulphonate, mono- or dihydrazine phthalate, isophthalate or terephthalate, mono-, di- or trihydroxy alkyl substituted hydrazine salts, mono-, di or trialkyl substituted hydrazine salts, monoaryl substituted hydrazine salts and mixed alkyl-aryl substituted hydrazine salts.  The treating solution which may be acidified by the addition of formic, acetic, hydrochloric, sulphuric, phosphoric or nitric acid, may also contain buffers, e.g. sodium phosphate and sodium acetate, wetting agents, e.g. salts of acyl alkyl taurides, corrosion inhibitors, e.g. water soluble nitrate salts, and chelating agents, e.g. amines having a plurality of hydrogen atoms of the amino group replaced by fatty carboxylic acid groups.