Patent GB-1387167-A (GB)
Title: Bleaching agent
IPC: C11D17/00
Filed: 1972-09-28
Abstract: 1387167 Bleaching composition PROCTER & GAMBLE LTD 27 Sept 1973 [28 Sept 1972] 44864/72 Heading DIP A particulate bleaching agent comprises a bleach surrounded by a water-impermeable layer of a material melting point 30 to 95‹C which is inert to or a stabiliser for the bleach and a further coating of a particulate water soluble inorganic hydrate-forming salt having a pH in a 1% by wt aqeous solution of at least 10.5. The bleach is an organic peroxy acid (e.g. diperodipic acid, diperazaleic acid and diperisophthalic acid), a compound which forms organic peroxy acid or one of its salts in dilute aqueous or dilute aqueous alkaline solutions (e.g. benzoyl succinyl peroxide and benzoyl glutaryl peroxide) or an 'activator' which forms an organic peroxy acid or salt thereof in alkaline solution containing perhydroxyl ions e.g. from inorganic peroxides (e.g. tetra ocethyl glycouril and sodium p-benzoyloxy benzene sulphonate. The water impermeable material may be a fatty acid, fatty alcohol, paraffin wax, saturated hydrocarbon or mixture thereof e.g. lauric acid and myristyl alcohol. Preferably the weight ratio of bleach to impermeable coating is from 5:1 to 1:2. Specified water soluble hydrate forming inorganic salts are sodium and potassium carbonate, phosphate and metasilicate. The wt ratio of inorganic salt to bleach plus impermeable material is preferably 1:6 to 2:1. In Example 1 a slurry of benzoyl glutaryl peroxide in slightly acidified water at 8‹C below its melting point was poured slowly into a stirred emulsion of lauric acid in slightly acidified water at 4‹C above its m.p. The mixture was rapidly cooled with continued stirring and the solid particles of the peroxide coated with lauric acid were filtered, air dried, sprayed with 8% water at pH 8, added slowly to a large excess of anhydrous sodium carbonate in a rotating drum and the mixture sieved to separate the coated particles from the sodium carbonate. Finally the coated particles were sprayed with 5% of their weight of polyethylene glycol of molecular wt 500 to 6000, preferably 1500. The particles were incorporated into a composition comprising sodium perborate tetrahydrate an anionic organic detergent, soap, sodium tripolyphosphate, sodium silicate and sodium sulphate. The composition is suitable for washing white and coloured fabrics at moderate temperatures (30‹C to 100‹C).  In Example 3 finely divided sodium pbenzoyloxy benzene sulphonate and anhydrous sodium carbonate were mixed in an inclined pan granulator and sprayed with melted myristyl alcohol. The granular product formed was sprayed with enough water to moisten the granules and tumbled with anhydrous sodium carbonate. The particles were used in a detergent composition comprising sodium perbonate tetrahydrate, sodium dodecylbenzene sulphonate, a non- ionic detergent, soap, sodium tripolyphosphate, sodium silicate and sodium sulphate. Sodium percarbonate may replace sodium perborate. Preferably the ratio of available oxygen in the organic peroxy acid (or its precursor) to that in the percarbonate or perborate is 3:1 to 1:6. Anionic, nonionic, ampholytic and zwitterionic surface active agents suitable for use with the bleaching agent are listed, as are suitable builder salts. The bleaching of nylon and cotton fabrics is disclosed.