Bleaching and dyeing; fluid treatment and chemical modification – Bleaching – Chemical
Patent
1997-01-17
1998-12-01
Anthony, Joseph D.
Bleaching and dyeing; fluid treatment and chemical modification
Bleaching
Chemical
25218636, 25218725, D06L 306, D06L 308, D06L 316, C01B 1106
Patent
active
058431900
DESCRIPTION:
BRIEF SUMMARY
This application is a 35 U.S.C. 371 filing of PCT/US 94/12747, filed Nov. 4, 1994.
TECHNICAL FIELD
The present invention relates to a liquid bleaching composition which is suitable for laundry applications including hand washing as well as washing with automatic washing machines.
BACKGROUND OF THE INVENTION
Liquid bleaching compositions are well-known in the art. Amongst the different bleaching compositions available, those relying on bleaching by hypochlorite are often preferred, mainly for performance reasons. Representative of the art is, for example, WO-88-05461 which discloses an aqueous composition comprising hypochlorite, sodium carbonate and sodium hydroxide and the use of said composition for removing stains from the fabrics.
However, the drawbacks associated with the use of chlorine-based compositions are that said compositions may both damage and yellow the fabrics.
It is therefore an object of the present invention to provide a hypochlorite-containing composition, suitable for use in laundry, whereby the fabric whiteness is improved.
It is a further object of the present invention to provide a hypochlorite-containing composition, suitable for use in laundry, whereby fabric safety is improved.
We have now found that the previous objects can be met by formulating hypochlorite bleach compositions consisting of an alkali metal hypochlorite, an alkali metal salt of silicate, a strong source of alkalinity and optionally an alkali metal salt of carbonate. Said compositions allow to provide outstanding fabric whiteness as well as outstanding fabric safety on the fabrics treated therewith. In its broadest aspect, the present invention is based on the surprising finding that, for any given aqueous composition comprising an alkali metal hypochlorite, adding an alkali metal salt of silicate will improve both the fabric whiteness and the fabric safety on the fabrics treated therewith.
A further advantage of the compositions of the present invention is that on top of their outstanding whitening action and fabric safety properties said compositions allow also good stain removal, in particular enzymatic stain removal.
Compositions comprising hypochlorite, a carbonate salt, a silicate salt and a strong source of alkalinity have been described in the art. Co-pending European patent application number 93870070.5 discloses compositions comprising hypochlorite, sodium hydroxide, a bleach stable perfume and as a buffering system, sodium carbonate and/or sodium silicate.
EP-A-311 175 to Unilever discloses a liquid sanitizer composition comprising at least 2% by weight of a caustic agent such as sodium hydroxide, from 0 to 1% of a surfactant, at least 3% by weight of an alkali metal hypochlorite and an alkali metal neutral silicate. Sodium carbonate is not disclosed. The compositions disclosed in the '175 patent application are used in industrial machines for bulk warewashing or fabrics washing to ensure an acceptable level of hygiene. The compositions of the '175 patent application prevent decomposition of hypochlorite and corrosion by hypochlorite. J02014298 (abstract) discloses a cleaning composition for cleaning machine vessel comprising an aqueous solution of 0.5% to 15% by weight of hypochlorite and 3% to 30% by weight of silicate, preferably sodium silicate. Silicate is said to prevent decomposition of hypochlorite and corrosion by hypochlorite. Neither sodium hydroxide nor sodium carbonate are disclosed.
J60055100 (abstract) discloses hard-surface cleaners comprising from 1% to 10% by weight of hypochlorite, from 0.5% to 5% by weight of alkali metal hydroxide, preferably sodium hydroxide and from 0.5% to 8% by weight of an inorganic colloid such as amongst others Mg silicate. No sodium carbonate is disclosed.
The state of the art further comprises other documents disclosing more complicated fully formulated detergent compositions such as thickened compositions, or surfactant-based compositions, which may comprise hypochlorite, a strong source of alkalinity, carbonate salt and/or silicate salt amongst oth
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Agostini Andrea
Agostini Francesco
Trigiante Giuseppe
Anthony Joseph D.
Aylor Robert B.
The Procter & Gamble & Company
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