Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1997-11-13
2001-04-03
Liott, Caroline D. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S303000, C510S380000, C008S108100, C252S187250, C252S187260
Reexamination Certificate
active
06211131
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to stable liquid bleach compositions useful in treating fabrics and particularly relates to hypochlorite bleach-containing aqueous cleaning compositions comprising sequestering agents as whitening and fabric strength enhancers.
BACKGROUND OF THE INVENTION
The quality of raw water and finished (treated) water varies considerably throughout the world. For instance, the types and levels of trace metals found in water from household taps can vary significantly from one country to another. The presence of certain trace metals often reduces the effectiveness of laundering aids and causes fabric damage.
Hypochlorite liquid bleaches have found wide commercial acceptance and are commonly used in a variety of household cleaning and laundering products. The effectiveness of hypochlorite bleach compositions is usually not adversely affected by trace metals found in water used in laundering. However, it has been found that the presence of iron and manganese metal ions in water used in laundering causes fabrics to yellow and deteriorate. This phenomenon is particularly pronounced when the bleaching composition is not used in combination with a laundry detergent.
In WO 96/00188 it was speculated that the presence of metal impurities in the washing environment catalyzed the attack of hypochlorous acid on fabrics with the generation of yellow oxidized species. It was believed that the metal ions are adsorbed on fabrics as colored species and catalyzed the degradation of the brighteners absorbed on fabrics. Furthermore, it was said that the metal ions stabilized colored pigments of enzymatic stains, such as blood and grass, that caused such stains to “set”. Finally, it was said that the metal ions catalyzed the depolymerization of cotton fibers which leads to reduced tensile strength of the fabrics thereby reducing fabric resistance.
To counter the deleterious effects caused by the presence of heavy metal ions in hypochlorite-containing cleaning compositions, the art has suggested the employment of various agents to improve fabric whiteness and integrity. These agents, for example, include periodate, silicates, and pyridine with carboxylic acid substituents. See, for example, WO 96/00188, and EP 06/53482, and EP 0653483.
While some of these complexing agents have demonstrated hypochlorite bleach enhancement in terms of fabric whitening and safety, they are not satisfactory for a number of reasons. First, these prior art complexing agents are expensive to use. Second, some of these complexing agents do not mitigate the dingying effect of hypochlorite on fabrics washed in water containing significant levels of iron and/or manganese ions.
SUMMARY OF THE INVENTION
The present invention is based in part on the discovery of a series of sequestering agents for use as a whitening and fabric strength enhancer for aqueous hypochlorite bleach compositions. It was found that the sequesterants when used with hypochlorite in the presence of heavy metal ions, particularly iron and/or manganese ions, provide significantly improved whitening. It is expected that the sequesterants will also provide fabric protection. The sequesterants comprise polycarboxylates. Most preferably, the sequesterant is selected from polyacrylic acid, a polyacrylic acid derivative, a copolymer of acrylic acid or methacrylic acid and a comonomer which is maleic acid or maleic anhydride and mixtures thereof. Adjuvants such as sodium hydroxide, sodium carbonate, fluorescent whiting agents, fragrances dyes, and thickening agents can also be employed in conjunction with the sequesterants.
In one aspect, the invention is directed to an hypochlorite bleach composition which consists essentially of an alkali metal hypochlorite and an effective amount of a polycarboxylate sequesterant. Preferred sequesterants include, for example, polyacrylic acid, polyacrylic acid derivatives, copolymers of acrylic acid or methacrylic acid and a comonomer which is maleic acid or maleic anhydride, and mixtures thereof.
In another aspect, the invention is directed to a method for laundering fabrics with improved whitening and reduced fabric damage, said method including the steps of:
a) providing, in a wash liquor containing (i) at least about 40 ppb of iron cations or (ii) at least about 10 ppb of manganese cations, or (iii) the cations of both (i) and (ii), and a fabric piece; and
b) adding prior to, contemporaneously with, or after, the step of providing of said fabric piece to said wash liquor a hypochlorite composition which comprises an effective bleaching amount of an alkali metal hypochlorite and an effective amount of a polycarboxylate sequesterant to mitigate the attack of said cations on said fabrics wherein the sequesterant is a polymer that is selected from the group consisting of polyacrylic acid, a polyacrylic acid derivative, a copolymer of acrylic acid or methacrylic acid and a comonomer which is maleic acid or maleic anhydride and mixtures thereof.
In a further aspect, the invention is directed to a wash liquor containing (i) at least about 40 ppb of iron cations, or (ii) at least about 10 ppb of manganese cations, or (iii) the cations of both (i) and (ii), said wash liquor further including:
a) a fabric piece which has a tendency to be attacked by said cations in said wash liquor, and
b) a hypochlorite composition which includes an effective amount of alkali metal hypochlorite and an effective amount of polycarboxylate sequesterant to mitigate the attack of said cations on said fabric piece.
Preferably, the sequesterant comprises at least about 0.1 ppm by weight of said wash liquor. Preferably, the hypochlorite composition is an alkali metal hypochlorite and said sequesterant has a molecular weight of between about 500 and 500,000 daltons, and preferably from about 3,000 to 70,000 daltons.
The hypochlorite bleach composition of the present is stable and typically, the amount of alkali metal hypochlorite remaining will range from about 90% to about 95% of the original concentration even after storage at ambient temperature for about 12 months or longer.
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Kaaret Thomas W.
Smith William L.
Burns Doane Swecker & Mathis L.L.P.
Liott Caroline D.
The Clorox Company
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