Bleaching and dyeing; fluid treatment and chemical modification – Bleaching – Chemical
Patent
1998-06-22
2000-09-19
Einsmann, Margaret
Bleaching and dyeing; fluid treatment and chemical modification
Bleaching
Chemical
510303, 510379, 510380, D06L 306
Patent
active
061205559
DESCRIPTION:
BRIEF SUMMARY
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, especially at lower temperature.
However, there are some limitations to the convenience of hypochlorite bleaches. In particular, it is well-known from consumers that the drawbacks associated with the use of hypochlorite-based compositions are that said compositions may damage and/or yellow the fabrics which are being bleached.
It is therefore an object of the present invention to provide a hypochlorite-containing composition, suitable for use in laundry application, 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 application, whereby fabric safety is improved.
We have now found that the previous objects can be met by formulating an alkaline liquid composition comprising an alkali metal hypochlorite or mixtures thereof and a pH buffering means with low sensitivity to water hardness, i.e. a pH buffering means which, when used in a 1M solution at pH 10, requires more than 2.5 mM of calcium ion, in order to cause precipitation at 25.degree. C. of the calcium salt of the alkali anion of said pH buffering means. Said composition allows to provide improved fabric whiteness and/or improved fabric safety on the fabrics treated therewith, as compared to the same composition without said pH buffering means with low sensitivity to water hardness according to the present invention. We have also found that, in the preferred embodiment of the present invention wherein the liquid hypochlorite bleach-containing compositions comprise said pH buffering means with low sensitivity to water hardness together with a precipitation agent like carbonate salt and/or silicate salt, outstanding whiteness and/or fabric safety performance are provided. Indeed, it has been found that the use of a pH buffering means with low sensitivity to water hardness together with a precipitation agent like silicate salt and/or carbonate salt in a hypochlorite bleaching composition results in a complementary effect on fabric whiteness performance and/or fabric safety performance.
An advantage of the compositions of the present invention is that they allow to provide outstanding fabric whitening action and/or fabric safety properties without compromising on the stain removal performance on different types of stains including bleachable stains (e.g. coffee), enzymatic stains (e.g. blood) and greasy stains (e.g. lipstick).
Another advantage of the compositions of the present invention is that said bleaching compositions are suitable for the bleaching of different types of fabrics including natural fabrics, (e.g., fabrics made of cotton, viscose, linen, silk and wool), synthetic fabrics such as those made of polymeric fibers of synthetic origin as well as those made of both natural and synthetic fibers. Indeed, the compositions of the present invention may be used on synthetic fibers despite a standing prejudice against using hypochlorite bleaches on synthetic fibers, as evidenced by warnings on labels of commercially available hypochlorite bleaches and clothes.
A further advantage is that the liquid compositions according to the present invention comprising a pH buffering means with low sensitivity to water hardness allow a prolonged through-the-bleach buffering action, i.e. to maintain the pH of the bleaching solution as high as possible during the whole bleaching cycle from the moment the dilution is completed, without increasing the pH of the compositions per se as compared to the same compositions but without said pH buffering means.
Compositions comprising hypochlorite and pH buffering means have been
REFERENCES:
patent: 1514068 (1924-11-01), Phair
patent: 2097517 (1937-11-01), Durgin
patent: 2435474 (1948-02-01), Soule
patent: 2829110 (1958-04-01), Robson
patent: 3640879 (1972-02-01), Fitzgerald, Jr.
Scialla Stefano
Trigiante Giuseppe
Camp Jason J.
Einsmann Margaret
Reed T. David
The Proctor & Gamble Company
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