Patent GB-795690-A (GB)
Title: Improvements in or relating to chlorite bleaching
IPC: D06L3/08
Filed: 1955-10-11
Abstract: Cellulosic material is treated in a metallic reaction chamber at an elevated temperature with a neutral solution comprising chlorine dioxide or an inorganic chlorite and a nitrogen compound having at least one hydrogen atom attached to the nitrogen atom and which will, at least slightly, dissociate in solution to yield ammonia.  The chlorite may be an alkali metal or alkaline earth metal chlorite, chlorites of sodium, potassium, calcium, barium and magnesium being specified, and the cellulosic material may be treated in the form of a slurry to which the bleaching composition is added in aqueous solution.  The nitrogen compound may be ammonium chloride, sulphate, nitrate, phosphate or acetate or aniline, morpholine, toluidine, methyl aniline, benzylamine, diphenylamine, diamylamine, methylamine, ethylamine, diethanolamine, urea, methylurea, ethylurea, diphenylurea, diethylurea, urethanes and other substituted ureas or thioureas, guinidines, substituted guanidines, acetamide, formamide or butyric amide, or monosubstituted alkyl or aryl amides.  The material treated may be a textile material or fibres obtained from wood or cotton linters or cellulose acetate, butyrate or propionate, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, cellulose acetate-propionate, cellulose acetate-butyrate, carboxymethyl-hydroxyethyl cellulose or acetylatedhydroxyethyl cellulose.  The cellulose material may be slurried in water or, if water-soluble, in methyl alcohol, ethyl alcohol, isopropyl alcohol or tertiary butyl alcohol, dioxane, tetrahydrofuran, the diethyl ether of ethylene glycol or an aqueous solution of one of these compounds. The treatment may be effected at 70 DEG  to 150 DEG  C. under sufficient pressure to maintain the slurrying medium in the liquid phase.  Cellulose esters may be treated in the aqueous media in which they are precipitated or may be prepared as a solid and then slurried.ALSO:Cellulosic material is bleached in a metallic reaction chamber at an elevated temperature with a neutral solution comprising chlorine dioxide or an inorganic chlorite and a nitrogen compound having at least one hydrogen atom attached to the nitrogen atom and which will, at least slightly, dissociate in solution to yield ammonia.  The chlorite may be an alkali metal or alkaline-earth metal chlorite, chlorites of sodium, potassium, calcium, barium and magnesium being specified, and the cellulosic material may be treated in the form of a slurry to which the bleaching composition is added in aqueous solution.  The nitrogen compound may be ammonium chloride, sulphate, nitrate, phosphate or acetate or aniline, morpholine, toluidine, methyl aniline, benzylamine, diphenylamine, diamylamine, methylamine, ethylamine, diethanolamine, urea, methylurea, ethylurea, diphenylurea, diethylurea, urethanes and other substituted ureas or thioureas, guanidines, substituted guanidines, acetamide, formamide or butyric amide, or monosubstituted alkyl or aryl amides.  The material treated may be a textile material or fibres obtained from wood or cotton linters or cellulose acetate, butyrate or propionate, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, cellulose acetate-propionate, cellulose acetate-butyrate, carboxymethyl-hydroxyethyl cellulose or acetylated-hydroxyethyl cellulose.  The cellulose material may be slurred in water or, if water-soluble, in methyl alcohol, ethyl alcohol, isopropyl alcohol or tertiary butyl alcohol, dioxane, tetrahydrofuran, the diethyl ether of ethylene glycol or an aqueous solution of one of these compounds. The treatment may be effected at 70 DEG  to 150 DEG  C. under sufficient pressure to maintain the slurrying medium in the liquid phase.  Cellulose esters may be treated in the aqueous media in which they are precipitated or may be preparde as a solid and then slurried.