Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2001-07-11
2004-05-04
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S223000, C510S227000, C510S229000, C510S230000, C510S514000, C510S521000
Reexamination Certificate
active
06730645
ABSTRACT:
TECHNICAL FIELD
The present invention relates to acidic rinse aid formulations used in automatic dishwashing. More particularly, the invention relates to a method for improving stability of a dye used in a colored aqueous acidic rinse aid composition to ambient and ultra-violet light radiation of a machine dishwasher rinse aid formulation.
BACKGROUND OF THE INVENTION
The use of rinse aids in commercial and institutional machine dishwashers and also in household automatic dishwashers, is well known. In automatic dishwashing, during the rinse cycle, a final rinse of fresh water serves to displace pre-final rinse water and its attendant detergent and soil residues. Rinse aid formulations are aqueous solutions containing a low foam nonionic surfactant. During the rinse cycle, the rinse aid is injected into the final fresh water rinse at a concentration of about 100 to about 500 ppm. The surfactant in the rinse water lowers the surface tension of the rinse water and improves the wetting action of the rinse water.
The inventors of the present invention have previously discovered that it is possible to formulate an aqueous rinse aid containing a low foam nonionic surfactant and a low molecular weight neutralized, partially neutralized, or non-neutralized polyacrylate polymer without the use of a compatibilizing high molecular weight polymer or a high cloud point co-surfactant, thus providing an acidic, stable aqueous rinse aid dispersion which reduces spotting and filming while improving sheeting action and drainage.
One major problem, however, associated with acidic, stable rinse aid dispersions is that when a dye is added in the composition to impart a pleasing color, especially a typical blue or green dye, such as a FD&C #1 Blue dye for example, there is a tendency for such rinse aid compositions to change color upon exposure to ambient and UV light, for example sunlight. Frequently, if not inevitably, acidic rinse aid products will be subjected to UV light (e.g., sunlight) repeatedly and over extended periods of time prior to use by the consumer. The formulations of typical automatic dishwashing (ADW) rinse aid products are specifically tailored to a color that has been proven to be aesthetically pleasing to consumers. Any change in the target formulation color, especially when clear or translucent bottle or other packaging container is used, can negatively impact the consumer's perception of the quality of the product.
Typically, in the past, colored rinse aid compositions have been formulated at or near neutral pH, since it has been generally heretofore understood that non-acidic rinse aid compositions will not reduce the dye stability to ambient and ultraviolet light radiation. The inventors of the present invention have addressed this dye stability issue in the present invention and provided an effective solution to this problem. Before the present invention, there has been no method or composition known heretofore that addresses this dye stability problem in acidic rinse aid compositions.
Accordingly, it has thus been desirable to have a colored acidic rinse aid product which is not significantly altered by UV light. Further, despite the above-mentioned disclosures in the art, it has been desirable to have an acidic rinse aid product which has superior performance in addition to a packaging appearance. It is extremely desirable that the packaging appearance (e.g., color) is maintained until the consumer has disposed of the product. The present invention overcomes the problems as set forth above.
BACKGROUND ART
U.S. Pat. No. 5,254,282, issued on Oct. 19, 1993 to Fusiak, discloses acidified paint removal formulations which are stabilized against color formation by inclusion of a chelating agent; and
U.S. Pat. No. 5,206,006, issued on Apr. 27, 1993 to Frontini et al. discloses a composition of the trinder type for detecting hydrogen peroxide evolved in a solution, which contains a chelating agent, relevant portions of both of these patents being incorporated herein by reference.
SUMMARY OF THE INVENTION
The invention meets the needs above by providing a method and composition for improving stability of a dye used in a colored aqueous acidic rinse aid composition to ambient and ultra-violet light radiation.
In one aspect of the present invention, the method for improving stability of a dye used in a colored aqueous acidic rinse aid composition to ambient and ultra-violet light radiation includes the step of adding a chelant to an acidic rinse aid composition. The chelant is present in an amount of at least 1 ppm by weight of the rinse aid composition.
In another aspect of the present invention, a colored acidic rinse aid composition exhibiting improved stability of a dye used therein to ambient and ultra-violet light radiation includes a low foaming nonionic surfactant present in a range of from about 2% to about 80% by weight of the rinse aid composition. The composition also includes a hydrotrope present in a range of from about 0.5% to about 20% by weight of the rinse aid composition. The composition further includes a polyacrylate polymer present in a range of from about 0.1% to about 15% by weight of the rinse aid composition. The polymer has a weight average molecular weight in a range of from about 1000 to about 50,000. The composition still further includes a chelant. The chelant is present in an amount of at least 1 ppm by weight of the rinse aid composition.
DETAILED DESCRIPTION OF THE INVENTION
In the preferred embodiment of the present invention, the method includes the step of adding a chelant to an acidic rinse aid composition. The chelant is desirably present in an amount of at least 1 ppm, preferably at least 50 ppm, more preferably at least 100 ppm and most preferably at least 150 ppm by weight of the rinse aid composition.
Chelants
In the preferred embodiment, the acidic rinse aid composition includes chelants selected from the group consisting of amino carboxylates, amino phosphonates, polyfunctionally-substituted aromatic chelants, and mixtures thereof. Other useful chelants include iron and/or manganese chelants. Amino carboxylates useful as optional chelants include ethylenediaminetetracetates, N-hydroxyethylethylenediaminetriacetates, nitrilo-triacetates, ethylenediamine tetraproprionates, triethylenetetra-amine-hexacetates, diethylene-triaminepentaacetates, and ethanoldiglycines, alkali metal, ammonium, and substituted ammonium salts therein and mixtures therein.
Polyfunctionally-substituted aromatic chelants include dihydroxydisulfobenzenes such as 1,2-dihydroxy-3,5-disulfobenzene, and ethylenediamine disuccinate (“EDDS”).
In the preferred embodiment, the chelant is selected from the group consisting of ethylene diamine tetra acetic acid carboxylate, diethylene triamine penta acetic acid carboxylate , and mixtures thereof. In another preferred embodiment, the chelants are selected from polyphosphonate, ethylene diamine tetra acetic acid carboxylate (EDTA) and diethylene triamine penta acetic acid carboxylate (DTPA). Most preferably, the chelant is ethylene triamine penta phosphoric acid.
Dyes
In the preferred embodiment of the present invention, the dye is selected from the group consisting of Pontamine Blue (Copper Phthalocyanine Dyestuff), and Liquitant Patent Blue (polymeric colorant) and FD&C Blue #1 (having the molecular formula C
37
H
34
N
2
Na
2
O
9
S
3
), and mixtures thereof. Preferably, the dye has a color selected from the group consisting of blue, green, or mixtures thereof. It has been found that the blue and green dyes typically used in rinse aid formulations, such as the FD&C #1, are unstable to UV light in acidic conditions unless the rinse aid composition is formulated with a chelant according to the present invention. It has been found that even the so-called “acid stable” dyes, such as Acid Blue 80, fade quickly when used in acidic rinse aids, i.e., the dye is colorless after an exposure of 1 to 2 days under UV light radiation, unless the rinse aid is formulated according to the present invention, with a chelant. Desi
Foley Peter Robert
Pieroni Lucio
Song Xiaoqing
Boyer Charles
Khosla Pankaj M.
The Procter & Gamble & Company
Waugh Kevin L.
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