Low foaming automatic dishwashing compositions

Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...

Reexamination Certificate

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Details

C510S220000, C510S226000, C510S376000, C510S379000, C510S535000

Reexamination Certificate

active

06326341

ABSTRACT:

TECHNICAL FIELD
The present invention is in the field of automatic dishwashing detergents comprising surfactants and preferably bleach. More specifically, the invention encompasses automatic dishwashing detergents (liquids, pastes, and solids such as tablets and especially granules) comprising builder (e.g., phosphate and/or citrate/carbonate), bleaching agent (e.g., hypochlorite; perborate; percarbonate) and a mixed surfactant system comprising a low cloud point nonionic surfactant and a charged surfactant selected from the group consisting of anionic surfactants, zwitterionic surfactants, and mixtures thereof. Preferred compositions contain perborate and/or percarbonate bleaching systems, further preferably comprising bleach activators and/or metal-containing bleach catalysts (e.g., manganese and/or selected cobalt/ammonia catalysts), and detersive enzymes (e.g., amylase; protease). Preferred methods for washing tableware are included.
BACKGROUND OF THE INVENTION
Automatic dishwashing, particularly in domestic appliances, is an art very different from fabric laundering. Domestic fabric laundering is normally done in purpose-built machines having a tumbling action. These are very different from spray-action domestic automatic dishwashing appliances. The spray action in the latter tends to cause foam. Foam can easily overflow the low sills of domestic dishwashers and slow down the spray action, which in turn reduces the cleaning action. Thus in the distinct field of domestic machine dishwashing, the use of common foam-producing laundry detergent surfactants is normally restricted. These aspects are but a brief illustration of the unique formulation constraints in the domestic dishwashing field.
Automatic dishwashing with bleaching chemicals is different from fabric bleaching. In automatic dishwashing, use of bleaching chemicals involves promotion of soil removal from dishes, though soil bleaching may also occur. Additionally, soil antiredeposition and anti-spotting effects from bleaching chemicals are desirable. Some bleaching chemicals (such as a hydrogen peroxide source, alone or together with tetraacetylethylenediamine, aka “TAED”) can, in certain circumstances, be helpful for cleaning dishware.
On account of the foregoing technical constraints as well as consumer needs and demands, automatic dishwashing detergent (ADD) compositions are undergoing continual change and improvement. Moreover environmental factors such as the restriction of phosphate, the desirability of providing ever-better cleaning results with less product, providing less thermal energy, and less water to assist the washing process, have all driven the need for improved ADD compositions.
In spite of such continuing changes to the formulation of ADD compositions, there continues to be a need for better cleaning ADD compositions, especially for removal of greasy soils. Typically, in other types of cleaning compositions such as laundry detergent compositions, cleaning improvements are continually being made by changing and improving the surfactants used. However, as noted hereinbefore, ADD compositions have the unique limitation of requiring very low sudsing compositions which is incompatible with most of the the surfactant systems and ingredients typically used in other cleaning compositions.
The exception is that low cloud point, low foaming nonionic surfactants have been used. But the cleaning performance therefrom has generally been very limited due to the requirement that low foaming nonionic surfactants are generally low cloud point nonionic surfactants, which have limited solubility in the wash solution. The lack of solubility of such nonionic surfactants greatly limits their cleaning ability, providing instead mainly spotting reduction benefits. Attempts at utilizing the more commonly used anionic surfactants have typically failed due to unacceptable foaming of such surfactants. Thus, there continues to be a need for ADD compositions containing surfactants which provide cleaning benefits (e.g., greasy soil removal benefits) without unacceptably high sudsing.
The present invention ADD composition comprising mixture of low cloud point nonionic surfactant and charged surfactant satisfy this long felt need. It is therefore an object of the present invention to provide ADD compositions comprising surfactant systems which provide cleaning benefits, especially greasy soil cleaning benefits (e.g., lipstick), while at the same time producing an acceptably low level of sudsing. These and other benefits of the present invention will be apparent from the detailed description which follows.
BACKGROUND ART
U.S. Pat. No. 4,272,394, issued Jun. 9, 1981 to Kaneko, WO 94/22800, published Oct. 13, 1994 by Olin Corporation, WO 93/04153, published Mar. 4, 1993 by the Procter & Gamble Co.
SUMMARY OF THE INVENTION
It has now been discovered that automatic dishwashing detergent (“ADD”) compositions comprising builder and a mixed low cloud point/charged surfactant system, preferably further comprising a bleaching agent and/or enzymes, provide superior cleaning, especially greasy soil removal benefits.
The present invention therefore encompasses automatic dishwashing detergent compositions comprising:
(a) from about 5% to about 90% (preferably from about 5% to about 75%, more preferably from about 10% to about 50%) by weight of the composition of a builder (preferably phosphate or nil-phosphate builder systems containing citrate and carbonate);
(b) from about 0.1% to about 15% (preferably from about 0.2% to about 10%, more preferably from about 0.5% to about 5%) by weight of the composition of a mixed surfactant system, wherein said mixed surfactant system comprises one or more low cloud point nonionic surfactants having a cloud point of less than 30° C. and one or more charged surfactants selected from the group consisting of anionic surfactants, zwitterionic surfactants, and mixtures thereof, the ratio of low cloud point nonionic surfactant to charged surfactant being within the range of from about 20:1 to about 1:5 (preferably from about 10:1 to about 1:2, more preferably from about 2:1 to about 1:1);
(c) optionally, from about 0.1% to about 40% by weight of the composition of a bleaching agent (preferably a hypochlorite, e.g., sodium dichloroisocyanurate, “NaDCC”, or source of hydrogen peroxide bleaching system, e.g. perborate or percarbonate), preferably also containing a cobalt bleach catalyst and/or a manganese bleach catalyst; and
(d) adjunct materials, preferably automatic dishwashing detergent adjunct materials selected from the group consisting of enzymes, chelating agents, and mixtures thereof.
The preferred compositions herein comprise a bleaching system which is a source of hydrogen peroxide, preferably perborate and/or percarbonate, and preferably also comprise a cobalt-containing bleach catalyst or a manganese-containing bleach catalyst. Preferred cobalt-containing bleach catalysts have the formula:
[Co(NH
3
)
n
(M)
m
(B)
b
]T
y
wherein cobalt is in the +3 oxidation state; n is 4 or 5 (preferably 5); M is one or more ligands coordinated to the cobalt by one site; m is 0, 1 or 2 (preferably 1); B is a ligand coordinated to the cobalt by two sites; b is 0 or 1 (preferably 0), and when b=0, then m+n=6, and when b=1, then m=0 and n=4; and T is one or more counteranions present in a number y, where y is an integer to obtain a charge-balanced salt (preferably y is 1 to 3; most preferably 2 when T is a −1 charged anion); and wherein further said catalyst has a base hydrolysis rate constant of less than 0.23 M
−1
s
−1
(25° C.). Also, in another mode, the compositions of the present invention are those wherein the bleach catalyst is a member selected from the group consisting of manganese bleach catalysts, especially manganese “TACN”, as described more fully hereinafter.
Additional bleach-improving materials can be present such as bleach activator materials, including tetraacetylethylenediamine (“TAED”) and cationic bleach activators, e.g., 6-tr

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