GB1010425A - Bleaching material containing protein - Google Patents

Abstract

An aqueous solution of performic acid is produced by the reaction of an aqueous solution of formaldehyde with an aqueous solution of hydrogen peroxide in the presence of 0.3-30% with reference to the total weight of the anhydrous formaldehyde and hydrogen peroxide to be reacted, of an organic or inorganic acid or a salt thereof, e.g. sulphuric, phosphoric, formic, acetic, lactic, maleic, citric or tartaric acid, as a catalyst. The solution may be stabilized by the addition of tetrasodium pyrophosphate, magnesium silicate, magnesium phosphate, complex magnesium-alkali metal salts of nitrilotriacetic acid, ethylene diamine tetracetic acid or hexamethylene diamine tetracetic acid, acetamide, formamide, alkali metal, citrates, ammonium citrate or maleic anhydride. Specifications 656,938, 804,781 and 810,439 are referred to.ALSO:Protein-containing materials, e.g. wool, silk, leathers and hog's bristles, are bleached by treating them with a liquor having a pH value of 2-8.5 comprising aqueous performic acid solution which has been prepared by the reaction of aqueous formaldehyde solution and aqueous hydrogen peroxide solution in the presence of 0.3-30% with reference to the total weight of the anhydrous formaldehyde and hydrogen peroxide to be reacted, of an p organic or unorganic acid or a salt thereof, e.g. sulphuric, phosphoric, formic, acetic, lectic, citric, maleic and tartaric acids, as a catelyst. The bleaching solution may be stabilised by the addition of tetrasodium pyrophasphate, magnesium silicote, magnesium phosphate, complex magnesium-alkali metal salts of aminocarboxylic acids which have more than one carboxylic group to one basic nitrogen, e.g. nitrilotriacetic acid, ethylene diamine tetracetic acid or hexamethylene diamine tetracetic acid, acetamide, formamide, alkali metal citrates, ammonium citrate or maleic amhydride, and may be adjusted to the desired pH value by the addition of ammonium or sodium carbonate. The treating solution may also contain optical bleaches e.g. 4, 5-diphenyl imidazolene disulphonate softeners and wetting agents, e.g. an octa or nonyl phenol polyglycol ethers. When working with a long liquor the material may be introduced into the bleaching liquor at 40 DEG -50 DEG C. and treated for 2-4 hours at 50 DEG C. Piece goods may be treated by a batchwise or continuous padding method in which they are impregnated on a padding machine with the bleaching liquor, squeezed, rolled up, wrapped in a waterproof sheet and then left for 10-15 hours at 15 DEG -25 DEG C. or for 2 hours or less at temperatures of 50 DEG C or higher, or after impregnation are introduced at open width into a steamer where they are allowed to remain for a few minutes.