Air bleaching catalysts with enhancer and moderating agent

Details Air bleaching catalysts with enhancer and moderating agent Air bleaching catalysts with enhancer and moderating agent

2002-03-13

2003-04-22

Gupta, Yogendra N. (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

With oxygen or halogen containing chemical bleach or oxidant...

C510S399000

Reexamination Certificate

active

06551977

ABSTRACT:

FIELD OF INVENTION
This invention relates to the protection of unsaturated moieties in a bleaching composition.
BACKGROUND OF INVENTION
The use of bleaching catalysts for stain removal has been developed over recent years. The recent discovery that some catalysts are capable of bleaching effectively in the absence of an added peroxyl source has recently become the focus of some interest, for example: WO9965905; WO0012667; WO0012808; WO0029537, and, WO0060045.
UK patent application 0030877.5, filed Dec. 18, 2000, discloses the use of an unsaturated surfactant as a bleach enhancement catalyst. However, there are stability problems associated with the interaction of the unsaturated surfactant and bleach enhancement catalyst.
DETAILED DESCRIPTION OF THE INVENTION
We have found that in some instances an unsaturated surfactant is degraded by an air bleaching catalyst in a non-desirable way. We have also found that in some instances a peroxyl bleaching catalyst together with a peroxyl species degrades an unsaturated surfactant in a non-desirable way. A solution to this problem is provided by the presence of an antioxidant, the presence of which still permits air bleaching of stains.
It is an object of the present invention to provide a composition that reduces the problem of malodour. This is provided by the presence of an antioxidant. It is a further object to provide the composition that has a reduced level of antioxidant present. This is provided by the presence of a combination of at least two antioxidants in the composition.
The combination of the at least two antioxidants providing in a solution containing oleic acid an effective reduction in the formation of hexanal from the oleic acid under ambient atmospheric conditions by a factor of at least three in comparison with same composition having a molar equivalent of a single antioxidant equivalent to the combined molar concentration of the at least two antioxidants, said single antioxidant being one of the at least two antioxidants.
The present invention provides a bleaching composition comprising an organic ligand which forms a complex with a transition metal for bleaching a substrate with a group selected from:
a) atmospheric oxygen, the bleaching composition upon addition to an aqueous medium providing an aqueous bleaching medium substantially devoid of a peroxygen bleach or a peroxy-based or peroxyl-generating bleach system; and,
b) a peroxygen bleach or source thereof, together with a surfactant having an allylic hydrogen, said surfactant having an HLB of greater than 2, and at least two antioxidants, whereby the combination of the at least two antioxidants provides in a solution containing oleic acid an effective reduction in the formation of hexanal from the oleic acid under ambient atmospheric conditions by a factor of at least three in comparison with same bleaching composition having a molar equivalent of a single antioxidant equivalent to the combined molar concentration of the at least two antioxidants, said single antioxidant being one of the at least two antioxidants.
In a preferred embodiment of the present invention is provided a bleaching composition for bleaching a substrate, the bleaching composition comprising:
(i) an organic ligand which forms a complex with a transition metal for bleaching with oxygen sourced from the air;
(ii) 0.01 to 60 wt/wt % of a surfactant having an HLB of greater than 15, the surfactant a sodium salt of an unsaturated carboxylic acid having an allylic hydrogen; and,
(iii) 0.001 to 5% wt/wt % of at least two antioxidants in a molar ratio of at least 5%, said bleaching composition comprising less than 2% mMol of peroxide per Kg, wherein upon addition of the bleaching composition to an aqueous solution and in the presence of the substrate and least 10% of any bleaching of the substrate is effected by oxygen sourced from the air and wherein the combination of the at least two antioxidants provides in a solution containing oleic acid an effective reduction in the formation of hexanal from the oleic acid under ambient atmospheric conditions by a factor of at least three in comparison with same bleaching composition having a molar equivalent of a single antioxidant equivalent to the combined molar concentration of the at least two antioxidants, said single antioxidant being one of the at least two antioxidants.
It is preferred that the bleaching composition is substantially devoid of a peroxygen bleach or a peroxy-based or peroxyl-generating bleach system. Nevertheless, as another aspect of the present invention a peroxyl source may be present such that “air bleaching” is suppressed. Generally, “air bleaching” catalysts are capable of operating in a peroxyl bleaching mode.
The surfactant having an allylic hydrogen has an HLB (hydrophilic/lipophilic balance) greater that 2, more preferably greater than 5, and most preferably greater than 10. Ideally, if the surfactant is a charged species the HLB is greater than 15. For a discussion of HLB the reader is directed to and article by Griffin, W. C. in J. Soc. Cosmetic Chemists Vol. 1 page 311, 1945 and Davies, J. T. and Rideal, E. K. in Interfacial Phenomena, Acad. Press, NY, 1961, pages 371 to 382. The HLB value requirement reflects the importance of the rate of solubility and dispersibility of the surfactant having an allylic hydrogen from the bleaching composition to the aqueous wash medium in conjunction with surface activity towards the substrate being washed. The threshold value of HLB as required excludes compounds that have an allylic which do not have the required surfactant properties, for example linoleaic or oleic acid have an HLB of 0.8.
It is preferred that the surfactant having an allylic hydrogen has a CMC of 2×10
−2
M or less. It is most preferred that the surfactant is anionic has a critical micelle concentration value of 3×10
−3
M or less. Generally, a surfactant will form a micelle when present in an aqueous solution above a specific concentration that is intrinsic to the surfactant. A micelle is a neutral or electrically charged colloidal particle, consisting of oriented molecules. Above what is known as the critical micelle concentration CMC amphiphilic compounds tend to adopt specific aggregates in aqueous solution. The tendency is to avoid contact between their hydrophobic alkyl chains and the aqueous environment and to form an internal hydrophobic phase. Such compounds can form monomolecular layers [monolayers] at the air-water boundary and bimolecular layers [bilayers] between two aqueous compartments. Micelles are spherically closed monolayers. This CMC criterion is another aspect that aids reduction of catalyst deposit.
The property required is that the surfactant used in the present invention is and forms a micelle at a concentration of 2×10
−2
M and below in an aqueous solution at a temperature of 25° C. One skilled in the art will be aware that the standard CMC is measured in deionized water and that the presence of other components in solution, e.g. surfactants or ions in solution will perturb the CMC value. The CMC values and requirement thereof as described herein are measured under standard conditions (N. M. Van Os, J. R. Haak, and L. A. M Rupert, Pysico Chemical Properties of Selected Anionic Cationic and Nonionic Surfactants Elsevier 1993; Kresheck, G. C. Surfactants—In water a comparative treatise—(ed. F. Franks) Chapter 2 pp 95-197 Plenum Press 1971, New York; and, Mukerjee, P. and Mysels K. J. Critical Micelle Concentrations of Aqueous Surfactant Systems, NSRDS-NBS 36, National Bureau of Standards. US Gov. Print office 1971, Washington, D.C.).
The present invention has particular utility as a bleaching composition in a commercial “air bleaching” liquid and granular “air bleaching” or peroxyl bleaching format. The degradation of unsaturated components during storage in the absence of an antioxidant often results in the formation of mal odour components due to the degradation of unsaturated compounds. The composition also serves to reduce the degra

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