Aluminosilicates and detergent composition
AssigneeUnilever Patent Holdings B.V.
InventorsGraham T. Brown, Theo J. Osinga, Michael J. Parkingston, Andrew T. Steel
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Abstract
Aluminosilicates in the form of P type zeolites are used as detergency builders and have a silicon to aluminium ratio not greater than 1.33, preferably above 0.9. These zeolites will usually have a calcium binding capacity of at least 150 mg CaO per gram of anhydrous aluminosilicate. A preferred form of the zeolite P has a silicon to aluminium ratio up to 1.15, and preferably above 0.9, with a tetragonally distorted cubic crystal structure. A process of the preparation of these zeolite P builders is described.
Claims12
An alkali metal aluminosilicate of the zeolite P type having a silicon to aluminium ratio not greater than 1.33 and having a calcium binding capacity of at least 150 mg CaO per g anhydrous aluminosilicate.
A process for the preparation of an alkali metal aluminosilicate of the zeolite P type having a silicon to aluminium ratio not exceeding 1.33, which comprises the steps of:
- (i) mixing together a sodium aluminate having a mole ratio Na.sub.2 O:Al.sub.2 O.sub.3 within the range of from 1.4 to 2.0 and a sodium silicate having a mole ratio SiO.sub.2 :Na.sub.2 O within the range of from 0.8 to 3.4 with vigorous stirring at a temperature within the range of from 25.degree. to boiling point to give a gel having the following composition:
- Al.sub.2 O.sub.3 :
- (1.75-3.5) SiO.sub.2 :
- (2.3-7.5) Na.sub.2 O:
- (80-450)H.sub.2 O;
- (ii) ageing the gel composition for 0.5 to 10 hours at a temperature within the range of from 70.degree. to boiling point with sufficient stirring to maintain any solids present in suspension;
- (iii) separating the crystalline sodium aluminosilicate thus formed, washing to a pH within the range of from 10 to 12.5, and drying to a moisture content of not less than 5 wt %.
Dependencies are inferred from the claim text.