Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Reexamination Certificate
1997-11-18
2002-03-26
Gerstl, Robert (Department: 1626)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With oxygen or halogen containing chemical bleach or oxidant...
C510S373000, C510S374000, C510S375000, C510S379000
Reexamination Certificate
active
06362151
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a granular detergent composition and more particularly, to a granular detergent composition containing secondary (2,3) alkyl surfactant, a bleaching agent and a bleach activator together which are combined within an optimum molar ratio range. The granular detergent composition as described herein surprisingly exhibits improved cleaning performance, especially with respect to greasy and oily stains.
BACKGROUND OF THE INVENTION
Typically, conventional detergent compositions contain mixtures of various surfactants in order to remove a wide variety of soils and stains from surfaces. For example, various anionic surfactants, especially the alkyl benzene sulfonates, are useful for removing particulate soils, and various nonionic surfactants, such as the alkyl ethoxylates and alkylphenol ethoxylates, are useful for removing greasy soils.
While the art is replete with a wide variety of surfactants for those skilled in the art of detergent formulation, most of the available surfactants are specialty chemicals which are not suitable for routine use in low cost items such as home laundering compositions. The fact remains that many home-use laundry detergents still comprise one or more of the conventional alkyl benzene sulfonates or primary alkyl sulfate surfactants. One class of surfactants which has found limited use in various compositions where emulsification is desired comprises the secondary alkyl sulfates. The conventional secondary alkyl sulfate surfactants are available as generally pasty, random mixtures of sulfated linear and/or partially branched alkanes.
For example, Rossall et al, U.S. Pat. No. 4,235,752, disclose a detergent surfactant which is a C
10-18
secondary alkyl sulfate containing 50% of ⅔ sulfate isomers and 40% of various other effective isomers. The surfactant materials disclosed by Rossall et al is for use primarily in dishwashing operations. Such materials have not come into widespread use in laundry detergents, since they do not offer any advantages over alkyl benzene sulfonates, especially with respect to water solubility which facilitates production of high-surfactant granular detergents and with respect to biodegradability. It would therefore be desirable to have a granular detergent composition containing a surfactant which has improved water solubility and biodegradability.
As is well known, even when those skilled in the art have selected an appropriate surfactant for a granular detergent composition, the compatibility of the surfactant with the other detergent ingredients must be addressed. For example, enzymes typically used in detergent compositions are notorious for their instability problems, especially when used in conjunction with detergent surfactants which tend to denature, degrade and deactivate the enzymes. While this is the case for amylases, cellulases and peroxidases, it is particularly true for lipases and proteases.
Such problems are especially exacerbated in the presence of a bleach and/or bleach/bleach activator system, both of which are known to oxidize enzymes. By way of example, Hardy et al, U.S. Pat. No. 4,536,314 (commonly assigned), disclose a granular detergent composition containing a bleaching compound, a bleach activator, an enzyme and surfactant, inter alia. By choosing appropriate ingredients and corresponding levels, Hardy et al produce a stable granular detergent composition. However, while Hardy et al disclose a granular detergent composition which is apparently effective, they only incorporate surfactants such as alkyl benzene sulfonates which do not have the solubility and biodegradability advantages to which were referred above.
Accordingly, despite the disclosures discussed above, there is a need in the art for a granular detergent composition containing a surfactant having improved water solubility and biodegradability. There is also a need in the art for such a granular detergent which has improved cleaning performance, especially with respect to greasy and oily stains.
SUMMARY OF THE INVENTION
The present invention meets the needs in the art identified above by providing a granular detergent composition which contains a surfactant which has improved solubility and biodegradability in combination with an enzyme and bleaching system. Moreover, the granular detergent composition also surprisingly exhibits superior cleaning performance, especially with respect to greasy and oily stains. The granular detergent composition contains a biodegradable surfactant, an enzyme and a bleaching system, together which are extremely stable in granular form. The bleaching system comprises a bleaching agent and a bleach activator which are present within an optimum molar ratio range. All percentages used herein are expressed as “percent-by-weight” unless otherwise indicated.
In accordance with one aspect of the invention, a granular detergent is provided. The granular detergent composition comprises: (a) from about 1% to about 40% of a secondary (2,3) alkyl sulfate surfactant; (b) from about 0.005% to about 5% of an enzyme; (c) from about 0.5% to about 20% of a peroxygen bleaching agent; and (d) from about 0.5% to about 20% of a bleach activator having the formula
wherein R is an alkyl group containing from about 5 to about 18 carbon atoms and LG is a leaving group, the conjugate acid of which has a pK
a
of from about 4 to about 13. The peroxygen bleaching compound and the bleach activator are in a molar ratio from about 1:1 to about 9:1.
In a preferred embodiment, the bleach activator has the formula
wherein R is an alkyl chain containing from about 1 to about 11 carbon atoms. A method of laundering soiled clothes is also provided. The method comprises the step of contacting the soiled clothes with an effective amount (typically at least about 0.01%/e, preferably at least about 0.05% by weight in the washing solution) of a granular detergent composition according to the invention in an aqueous media.
Accordingly, it is an object of the present invention to provide a granular detergent composition containing a surfactant having improved solubility and biodegradability. It is also an object of the invention to provide such a granular detergent which has improved cleaning performance and stability. These and other objects, features and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of the preferred embodiment and the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the broadest aspect, the granular detergent composition of the invention comprises a secondary (2,3) alkyl sulfate surfactant, an enzyme, a peroxygen bleaching agent, and a bleach activator wherein the peroxygen bleaching compound and the bleach activator are in a molar ratio from about 1:1 to about 9:1. Other preferred variants of the granular detergent composition are described hereinafter.
Secondary (2,3) Alkyl Sulfate Surfactant
The granular detergent composition preferably contains from about 1% to about 400/%, more preferably from about 2.6% to about 20%, and most preferably from about 3.3% to about 16% of a secondary (2,3) alkyl sulfate surfactant as described herein. For the convenience of those skilled in the art the following discussion of the secondary (2,3) alkyl sulfates used herein will be distinguished from conventional alkyl sulfate surfactants where appropriate.
Conventional primary alkyl sulfate surfactants have the general formula
ROSO
3
−
M
+
wherein R is typically a linear C
10
-C
20
hydrocarbyl group and M is a water-solubilizing cation. Branched-chain primary alkyl sulfate surfactants (i.e., branched-chain “PAS”) having 10-20 carbon atoms are also known; see, for example, European Patent Application 439,316, Smith et al, filed Jan. 21, 1991, the disclosure of which is incorporated herein by reference.
Conventional secondary alkyl sulfate surfactants are those materials which have the sulfate moiety distributed randomly along the hydrocarbyl “backbone” of t
Getty Edward Eugene
Wichmann Todd Edmund
Dressman Marianne
Gerstl Robert
Miller Steven W.
The Procter & Gamble & Company
William Zerby Kim
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