Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1998-05-11
2001-05-29
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S220000, C510S223000, C510S233000, C510S288000, C510S323000, C510S349000, C510S434000, C510S441000, C510S480000, C510S504000, C510S514000
Reexamination Certificate
active
06239091
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a nonchlorine containing machine dishwashing detergent or rinse aid formulation which delivers excellent final glassware appearance.
BACKGROUND OF THE INVENTION
Machine dishwashing detergents constitute a generally recognized distinct class of detergent compositions, particularly as compared to detergents designed for fabric laundering. As an example, a spotless and film-free appearance of glasses and silverware is the expected final result of a machine dishwashing run while, in many laundering operations, substances which may leave a greasy, oily or soapy residue can be tolerated.
In general, machine dishwashing detergents are mixtures of ingredients whose purpose, in combination, is to break down and remove food soils; to inhibit foaming caused by certain food soils; and to remove stains such as might be caused by beverages such as coffee and tea or by vegetable soils such as carotenoid soils. While necessary for these various cleaning benefits, machine dishwashing detergents can also create or exacerbate other problems. As an example, carbonate and phosphate salts, often detergent ingredients, are known to contribute to the formation of hard water films on glasses. In European applications, the water used to prepare the solution for the washing process is often treated (softened) to remove hardness ions such as calcium and magnesium with the result that hard water residues on washware are reduced. Nevertheless, spotting and filming from soil residues and precipitates from the detergent formulation can remain a problem, especially if the ion exchange unit serving the dishwashing machine is operating inefficiently.
Conventional machine dishwashing detergents employ strong alkalis such as sodium hydroxide, bleaches such as hypochlorite, and builders such as phosphates in order to assist in the cleaning steps outlined above. However, environmental factors, such as restrictions on phosphate and chlorine levels, and safety considerations have lead to the search for a new class of lower pH detergent formulations. Further, conventional formulations can damage items unique to machine dishwashing such as silverware, glassware and dishware. Certain of these items can be expensive to replace and force the consumer to separate them out from the rest of the table ware for hand washing—an obvious inconvenience. This new class of detergent formulations employs various detersive enzymes, including amylolytic and proteolytic enzymes, to compensate for the loss in cleaning effectiveness inherent at these lower pH values. Unfortunately, the conventional hypochlorite bleach system is incompatible with this enzymatic route and, as a consequence, oxygen bleaching systems have been adopted.
While the soil removal properties of these enzymatic formulations can match that of the conventional detergents, they have one notable weakness in the area of spotting and filming on glasses. The absence of chlorine bleach, alkalinity and phosphate builders generally results in higher spotting and filming scores under controlled laboratory testing and in a higher frequency of complaints from consumers in these two areas.
Spotting and filming of glassware are the chief criteria by which the performance of a dishwashing formulation is judged. Spotting is an obvious reference to discrete residues on glassware which have resulted when water droplets have completely evaporated and left behind any dissolved solids. Filming refers to a more uniform deposition over a large, contiguous portion of the glass surface. Without wishing to be bound by theory, it is believed that this film can sometimes be of organic origin (resulting from soil in the wash liquor) but is also often inorganic in nature, due to the formation of some mineral precipitate.
Accordingly, it is an object of the present invention to provide a new and improved machine dishwashing composition. Preferred compositions are free from chlorine bleach but may, optionally, contain an oxygen bleach. It is another object herein to provide dishwashing detergent compositions which contain effective levels of a cationic or amphoteric polymer which provides superior glassware appearance as evidenced by reduced spotting and filming. Another object herein is to provide a dishwashing rinse aid formulation containing an effective level of the cationic or amphoteric polymer.
DESCRIPTION OF THE PRIOR ART
Low molecular weight homopolymers of acrylic acid (such as Acusol 445, ex Rohm and Haas) discussed in Witak, D. et al. “Exploring Options for Dishwashing Detergents in the 1990s”, HAPPI, August 1990, p. 64 may be used in combination with a reduced or zero level of a phosphate builder, to give a reduced film score on glasses.
A copolymer of maleic acid or maleic anhydride and a C
2-4
olefin comonomer is described as an additive for chlorine-free machine dishwashing detergent formulations in lieu of chlorine bleach in U.S. Pat. No. 5,232,622. This hydrophobically modified polyacrylate is also described as reducing the incidence of spot formation with a margarine/milk soil in a zero phosphate formulation in Shulman, J. E. “Non Phosphate ADDS”, (July 1992) HAPPI, p. 130. Both spotting and filming are controlled by a combination of Acusol 460ND and either of Acusol 479N (a copolymer of acrylic acid and maleic acid) or Acusol 445. Such a combination of polyacrylates has also been described in U.S. Pat. No. 5,279,756.
Terpolymers of acrylic acid, acrylamide or butyl acrylate, and an aminoacryloyl derivative are disclosed as being useful at 0.5 to 7% levels in a machine dishwashing detergent formulation for reducing spotting and filming in the presence of a margarine/milk soil in U.S. Pat. No. 5,308,532. The performance of said terpolymers was found to surpass that of a 4500 MW homopolymer of acrylic acid (i.e. Acusol 445N, ex. Rohm and Haas). Similar claims are made for a copolymer of acrylic acid and the aminoacryloyl derivative in EP 0 560 519 A2.
Low molecular weight homopolymers of maleic acid are disclosed in U.S. Pat. No. 5,545,348 as being superior to copolymers of acrylic acid and maleic acid or to copolymers of maleic acid and an olefin comonomer with respect to reducing filming.
U.S. Patent No. 5,597,789 discloses a dishwashing composition comprising a mixture of disilicate and a low molecular weight, modified polyacrylate copolymer. The copolymer was described to reduce filming on glassware relative to acrylic acid/maleic acid copolymers of 70,000 MW or acrylic acid homopolymers of 4500 MW.
In summary, the prior art teaches the use of anionic, vinyl polymers consisting chiefly of acrylic acid or modified polyacrylates for the improvement of spotting and filming in chlorine-free machine dishwashing detergent formulations. However, the prior art does not suggest that cationic polymers reduce spotting and filming during machine dishwashing. Nor does it suggest that cellulosic materials, and especially cationically modified cellulose polymers, should offer any benefit in glass appearance.
SUMMARY OF THE INVENTION
It has now been discovered that a class of water soluble, cationic or amphoteric polymers provide enhanced appearance to glassware when incorporated in the dishwashing process as evidenced, in part, by a reduction of formation of spots and film on washed glass articles.
The present invention comprises incorporation of specific water soluble cationic or amphoteric polymers in the dishwashing process to improve the appearance of washed glass articles. The essential polymers in this invention may be incorporated at any point in the dishwashing process. The polymers may be incorporated into typical detergent or rinse aid formulations, or may be incorporated in any desired form such as tablets, powders, granulates, pastes, liquids, and gels.
DETAILED DESCRIPTION OF THE INVENTION
The present invention comprises incorporation of water soluble cationic or amphoteric polymers in the dishwashing process to improve the appearance of washed glass articles. The essential polymers in this invention may be incorporated at any po
Carnali Joseph Oreste
Tartakovsky Alla
Winters John Robert
Boyer Charles
Gupta Yogendra N.
Lever Brothers Company Division of Conopco, Inc.
Squillante, Jr. Edward A.
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