PREVENTION OF SCALE-FORMING DEPOSITS IN AQUEOUS SYSTEMS CONTAINING HARD WATER

摘要

1314790 Sequestering; softening water JOH A BENCKISER GmbH 25 Oct 1971 [20 Nov 1971] 49413/71 Heading C1C [Also in Division C5] Hard water used in cleaning compositions is softened by the addition of (A) dextrin and (B) an aminoalkylene phosphoric acid or an alkylene phosphonic acid, the wt. ratio of (A) : (B) being 1 : 1 to 50 : 1. The mixture is added to water in concentrations of 10 to 30 mg and up to 500 mg per litre. Typical compounds are (A) starch syrups of 20-60 DE (dextrose units) containing dextrin, glucose and maltose and (B) 1-hydroxyethane-1,1-diphosphonic acid, nitrilotri(methylene phosponic acid), diethylene triamine penta (methylene phosphonic acid) and 1,2-cyclohexane diamine tetra-(methylene phosphonic acid). Optional additions are (C) polymers and copolymers of acrylic acid and methacrylic acid. In examples, the sequestrants are added to aqueous solutions of NaOH containing (I) acid methyl (mixed mono- and di-)esters of phosphoric acid; (II) acid methyl isopropyl ester of phosphoric acid; (III) gluconic acid; (IV) sodium silicate, Na 2 CO 3 , Na 2 SO 4 and Na 3 PO 4 ; to produce solutions for washing bottles.