Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-09-05
2004-06-01
Mruk, Brian P. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S351000, C510S356000, C510S357000, C510S413000, C510S414000, C510S421000, C510S426000, C510S475000, C008S137000
Reexamination Certificate
active
06743763
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to stable aqueous laundry detergents containing vinyl pyrrolidone copolymers. Specifically, this invention relates to stable aqueous laundry detergents that contain a copolymer of vinyl pyrrolidone and vinyl acetate, in combination with certain surfactants.
BACKGROUND OF THE INVENTION
Polyvinylpyrrolidone (PVP) is used in laundry detergents to complex vagrant dyes that are released from colored fabrics during the wash process and prevent their redeposition on other garments. This feature, called dye transfer inhibition, or DTI, can be exploited to maximize colorcare performance in powder laundry detergents. In powder detergents formulations, such PVP polymers can simply be dry-blended during the manufacture of powder detergents. In general, the dye-complexation efficiency of the polymer increases with increasing molecular weight of the polymer. Thus, PVP with a molecular weight of about 40,000 gives relatively better DTI, while PVP of a molecular weight of about 9,000 gives relatively poorer DTI, when used at identical levels.
It is also desirable to use nonionic surfactants in laundry compositions to increase the efficacy of the detergent in removing oily soil. Particularly preferred for this use are the commercially available alcohol ethoxylates. Likewise, anionic surfactants are commonly used in detergent compositions as soil removers. Particularly preferred for this use are the linear or branched alkylbenzene sulfonates.
Powdered laundry detergents containing PVP, nonionic surfactants, and anionic surfactants can be readily formulated either by conventional spray-drying techniques or by agglomeration. However, when PVP is incorporated into an aqueous detergent composition containing nonionic surfactants, stability problems are often encountered, especially when higher molecular weight PVP is used. The instability of an aqueous detergent composition manifests itself by phase separation upon standing. It is believed that the instability of such formulations is due to the incompatibility of the PVP and nonionic surfactant.
While it is desirable to use PVP of higher molecular weights because of the higher DTI, it is difficult to formulate stable aqueous detergent compositions containing both high molecular weight PVP and nonionic surfactant. However, it is possible to prepare stable aqueous detergent compositions containing nonionic surfactant by sacrificing the DTI properties thereof and incorporating therein lower molecular weight PVP.
It is an object of the invention to provide a detergent compositions containing both PVP copolymers and nonionic surfactant, which are aqueous-based, stable and exhibit acceptable DTI properties and oily soil detergency properties.
While it has been known to use certain PVP copolymers, including copolymers of vinyl pyrrolidone and vinyl acetate in powdered laundry detergent, such as disclosed in Tanner, U.S. Pat. No. 3,749,682, there remains a need to be able to incorporate such materials in a stable, aqueous detergent formulation.
We have found that stable, aqueous detergents can be prepared with certain copolymers of vinylpyrrolidone and vinyl acetate in combination with certain amounts of anionic and nonionic surfactants.
SUMMARY OF THE INVENTION
The present invention provides a stable aqueous laundry detergent composition comprising:
a) from 0.05 to 10 percent by weight of a copolymer comprising, as polymerized units,
(i) from about 20 to about 80 mole percent vinyl pyrrolidone;
(ii) from about 1 to about 80 mole percent vinyl acetate; and
(iii) optionally, from 0 to about 20 mole percent of one or more additional polymerizable monomers;
b) from 5 to 60 percent by weight of a combination of
(i) anionic surfactant; and
(ii) nonionic surfactant having a cloud point measured in a 0.1 percent aqueous solution of less than 60° C.;
wherein the weight ratio of anionic surfactant to nonionic surfactant is at least 3 to 1 when the detergent composition contains the copolymer at a level up to about 1 percent by weight, and
wherein the weight ratio of anionic surfactant to nonionic surfactant is at least 4 to 1 when the detergent composition contains the copolymer at a level of at least about 1 percent by weight; and
c) from 30 to 85 percent by weight water.
The present invention also provides a method for inhibiting dye transfer during washing of natural or synthetic fabrics wherein the fabrics are treated with a wash liquor comprising the stable aqueous laundry detergent composition described above.
DETAILED DESCRIPTION OF THE INVENTION
The stable aqueous laundry detergent composition of the invention comprises from about 0.05 to 10 percent by weight of a copolymer comprising, as polymerized units, from about 20 to about 80 mole percent vinyl pyrrolidone, from about 1 to about 80 mole percent vinyl acetate, and optionally, from 0 to about 20 mole percent of one or more additional polymerizable monomers. Preferably, the copolymer comprises, as polymerized units, vinyl pryrrolidone at a level of from about 50 to about 80 mole percent. Preferably, the copolymer comprises, as polymerized units, vinyl acetate at a level of at least about 20 mole percent, most preferably from about 20 to about 50 mole percent. The copolymer optionally comprise, as polymerized units, one or more additional polymerizable monomers. Suitable additional polymerizable monomers include, for example, acrylic acid, acrylic acid esters, maleic acid, maleic anhydride, ethylene, methacrylic acid, methacrylate esters and substituted methacrylate esters, vinyl imidazole, vinyl alcohol, methylvinyl ether, styrene, vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, crotonic acid, itaconic acid, and vinyl sulfonate. When used, the one or more additional polymerizable monomers are present in the copolymer at levels up to about 20 mole percent, preferably up to about 10 mole percent, most preferably up to about 5 mole percent.
The copolymers suitable for use in the present invention generally have a number average molecular weight of from about 5,000 to about 1,000,000, preferably from about 10,000 to about 100,000. Higher molecular weight polymers tend to be more difficult to synthesize, while lower number average molecular weight polymers lead to compositions with less than optimum detergency properties.
The copolymers are prepared by known methods, for example by radical polymerization of the monomers in a water miscible organic solvent. Suitable copolymers and methods for their preparation are described in U.S. Pat. No. 5,122,582, the disclosure of which is hereby incorporated by reference. Suitable copolymers for use in the present invention include certain commercially available vinyl pyrrolidone/vinyl acetate copolymers such as Luviksol® VA73W polyvinyl pyrrolidone polymer and Luviksol® VA64 polyvinyl pyrolidone polymer available from BASF Corporation.
The copolymers are present in the laundry detergent compositions of the present invention at a level of from 0.05 percent to 10 percent by weight. Preferably the copolymer is present in the laundry detergent compositions of the present invention at a level of less than about 5 percent by weight, more preferably at a level of less than about 3 percent by weight, most preferably at a level of less than about 2 percent by weight. For improving the DTI performance, the detergent compositions will preferably contain at least 0.1 percent by weight, more preferably at least 0.25 percent by weight, and most preferably at least 0.5 percent by weight of the copolymer.
The stable aqueous detergent compositions of the present invention also contain one or more anionic surfactants. A wide range of anionic surfactants is useful in the invention. Useful anionic surfactants include alkyl aryl sulfonates, alkyl sulfonates, alkyl sulfates, alkyl ether sulfates, alkyl phosphates, amine oxides, isethionates, C
8
-C
30
fatty acid soaps, taurines, betaines, sulfobetaines, and mixtures thereof. A preferred anionic sufactant is LAS, which is an alkyl aryl sulfonate
Gopalkrishnan Sridhar
Guiney Kathleen M.
Banchik David T.
BASF Corporation
Mruk Brian P.
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