Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-12-22
2002-10-08
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S224000, C510S229000, C510S230000, C510S232000, C510S233000, C510S438000, C510S446000
Reexamination Certificate
active
06462006
ABSTRACT:
This invention relates to a dishwasher detergent in solid form containing a builder combination of conventional phosphates and crystalline layer silicates. Despite its phosphate content, the detergent according to the invention offers improved protection to sensitive tableware, more particularly glasses and decorated tableware, and develops high cleaning performance and, in some cases, further improved cleaning performance compared with conventional phosphate-containing dishwasher detergents.
Now that domestic dishwashing machines are used on a relatively wide scale, it is known that highly alkaline phosphate/metasilicate-based dishwasher detergents, although developing high cleaning performance, show unfavorable behavior in regard to corrosion of decorated tableware, i.e. colored on-glaze and in-glaze decorations applied to china, decorated glasses and gold decorations gradually lose color intensity and brilliance.
The citrate- or phosphate-based low-alkali dishwasher detergents introduced onto the market in recent years also have the above-mentioned effect, although to a lesser extent.
These disadvantages can largely be eliminated by adding relatively large quantities of water-soluble amorphous silicates, more particularly amorphous disilicates. At the same time, however, glasses undergo irreversible damage after only a few dishwashing programs with disilicate-containing detergents, as reflected in clouding and iridescence (iridescent colors).
European patent application EP-A-0 504 091 (Viking) describes phosphate-free dishwasher detergents which develop high cleaning performance against tea stains. These known detergents contain about 5 to 15% by weight of crystalline layer silicates and, in addition, 10 to 15% by weight of citric acid and also (co)polymeric polycarboxylates. Unfortunately, the overall cleaning performance of these low-alkali dishwasher detergents against problem soils apart from tea is unsatisfactory. Although their performance in removing tea stains is very good, it could still be improved.
The dishwasher detergents described in International patent application WO-A-94/16047 (Procter & Gamble) show improvements in the protection of silverware through the use of builders, bleaching agents released at a certain time and paraffin oil in quantities of 0.05 to 2.5% by weight. Citrate-containing formulations are clearly preferred. Other suitable builders are alumosilicates, phosphates and even crystalline layer silicates. Combinations of phosphate and crystalline layer silicates are not mentioned or even suggested, nor is there any reference to advantages arising out of the use of such builder combinations.
Finally, International patent application WO-A-96/12783 (Henkel) describes phosphate-free or low-phosphate dishwasher detergents based on citrate-containing formulations incorporating crystalline layer silicates which combine improved protection of decoration and glassware with high cleaning performance against tea stains. Unfortunately, the overall cleaning performance is again in need of improvement.
European patent application EP-A-0 416 366 (Hoeschst) describes a dishwasher detergent which contains 30% by weight of sodium tripolyphosphate, 30% by weight of crystalline sodium layer silicate, preferably—as a proton donor—mineral acid and/or polycarboxylic acid and/or hydroxypolycarboxylic acids and/or phosphonic acids and/or acidic salts or esters thereof and which, overall, has a relatively low pH value. This known dishwasher detergent is characterized by its high cleaning performance.
However, detergents containing crystalline layer silicates as a builder raw material are also attended by the disadvantage that lime deposits can be formed on glass and crockery on account of the slow dissolving rate of the crystalline layer silicate. In addition, the raw material consists of very fine particles and contains large amounts of dust which can lead to production problems both in the manufacture of powders and granules and in the manufacture of dishwasher tablets.
Hitherto, there has been no satisfactory solution to the problem of ensuring decoration—and glass-protecting cleaning in combination with high cleaning performance as demanded by the consumer against such problem soils as tea, milk/milk products, egg/protein products, etc. coupled with safe manufacture free from production problems.
Accordingly, the problem addressed by the present invention was to provide a dishwasher detergent which would not have the disadvantages mentioned above, i.e. which would not cause any damage to glass, even after repeated use, but at the same time would develop high cleaning performance against tea stains and an excellent overall cleaning performance and which could be produced without any production problems both in the manufacture of powders and granules and in the manufacture of tablets.
It has surprisingly been found that this problem can be solved by phosphate-containing dishwasher detergents providing they contain crystalline layer silicates in a certain compounded form in addition to phosphates.
Accordingly, the present invention relates to a solid dishwasher detergent containing conventional phosphates and other typical ingredients, characterized in that, in addition to the phosphates, the detergent contains as an additional builder a powder-form or granular additive containing a crystalline layer silicate corresponding to general formula (I):
NaMSi
x
O
2x+1
·y H
2
O (I)
in which M is sodium or hydrogen, x is a number of 1.9 to 22 and preferably 1.9 to 4 and y is a number of 0 to 33, and (co)polymeric polycarboxylic acid as key constituents.
Conventional phosphates suitable for use as builders in dishwasher detergents include in particular alkali metal phosphates and polymeric alkali metal phosphates which may be present in the form of their alkaline, neutral or acidic sodium or potassium salts. Examples of such phosphates are trisodium phosphate, tetrasodium diphosphate, disodium dihydrogen diphosphate, pentasodium tripolyphosphate, so-called sodium hexametaphosphate, oligomeric trisodium phosphate with degrees of oligomerization of 5 to 1000 and more particularly 5 to 50 and the corresponding potassium salts or mixtures of sodium hexametaphosphate and the corresponding potassium salts or mixtures of sodium and potassium salts. The salts of the tripolyphosphate are particularly preferred. They are used in quantities of more than 30% by weight to 65% by weight and, more particularly, from 35 to 60% by weight, expressed as water-free active substance and based on the formulation as a whole.
Crystalline layer silicates corresponding to formula (I) are marketed by Clariant GmbH (Germany) under the trade name Na-SKS, including for example Na-SKS-1 (Na
2
Si
22
O
45
xH
2
O, kenyaite) Na-SKS-2 (Na
2
Si
14
O
29
xH
2
O, magadiite), Na-SKS-3 (Na
2
Si
8
O
17
xH
2
O), Na-SKS-4 (Na
2
Si
4
O
9
xH
2
O, makatite).
Compositions particularly suitable for the purposes of the invention are those containing crystalline layer silicates corresponding to formula (I) in which x is 2. Of these, Na-SKS-5 (&agr;-Na
2
Si
2
O
5
), Na-SKS-7 (&bgr;-Na
2
Si
2
O
5
natrosilite), Na-SKS-9 (NaHSi
2
O
5
.H
2
O), Na-SKS-10 (NaHSi
2
O
5
.3H
2
O, kanemite), Na-SKS-11 (&tgr;-Na
2
Si
2
O
5
) and Na-SKS-13 (NaHSi
2
O
5
), but especially Na-SKS-6 (&dgr;-Na
2
Si
2
O
5
), are particularly suitable. An overview of crystalline layer silicates can be found, for example, in the articles published in “Hoechst High Chem Magazine 14/1993”, pages 33-38 and in “Seifen-Öle-Fette-Wachse”, Vol. 116, No. 20/1990”, pages 805-808. According to the invention, the crystalline layer silicates corresponding to formula (I) are at least partly introduced into the dishwasher detergents according to the invention through the builder additive used in accordance with the invention. In one preferred embodiment of the invention, the crystalline layer silicates corresponding to formula (I) are introduced into the dishwasher detergents according to the invention solely through the builder additive used in accordance with
Bauer Harald
Haerer Juergen
Holz Josef
Krings Peter
Mueller-Kirschbaum Thomas
Douyon Lorna M.
Harper Stephen D.
Henkel Kommanditgesellschaft auf Aktien
Murphy Glenn E.J.
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