Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Enzyme component of specific activity or source
Reexamination Certificate
1997-07-14
2002-08-27
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Enzyme component of specific activity or source
C510S392000, C510S321000, C510S309000, C510S312000, C510S313000, C510S334000, C510S320000, C510S530000, C510S532000, C510S507000
Reexamination Certificate
active
06440922
ABSTRACT:
The present invention relates to a detergent composition comprising an amylase enzyme and a small particle size zeolite component as a sequestering agent for water hardness.
Conventionally, water soluble inorganic phosphates, such as sodium tripolyphosphate, have been used as builders for laundry detergents.
More recently, alkali metal aluminosilicate ion-exchangers, particularly crystalline water insoluble sodium aluminosilicate zeolites, have been proposed as replacements for the inorganic phosphates.
For example, EP 21 491A (Procter & Gamble) discloses detergent compositions containing a builder system which includes zeolite A, X or P (B) or a mixture thereof. EP 384070A (Unilever) discloses specific zeolite P materials having. an especially low silicon to aluminium ratio not greater than 1.33 (hereinafter referred to as zeolite MAP) and describes their use as detergency builders.
The Applicants have now surprisingly found that a problem may occur when a water insoluble zeolite having a small particle size, is used as a detergency builder in a composition formulated for use in the laundering of fabrics. The problem has been found to be particularly pronounced when the zeolite is zeolite MAP.
The choice of a small particle size for a zeolite MAP component, that is to say particles having a particle size, measured as a d
50
value, of up to 1.0 micrometres has previously been taught to be preferred in the art, as represented, for example, by EP 384070 A.
The problem relates to the formation of white residues, which adhere to the fabrics and remain thereon at the end of a laundry washing process. The degree of residue formation may vary. On coloured fabrics the appearance of the white residues tends to be visually more apparent than on white fabrics. White residues frequently form on areas of fabric where there is a stain present, interfering with and preventing the complete removal of the stain. As a result of the visible contrast between the white residues and the coloured fabric, the stained area on which white deposits have formed may be more noticeable that the original stain.
It has been established that when an amylase enzyme is employed in compostions containing zeolite in small particle size form that the problem of the white residue formation on the fabrics is reduced.
Whilst the prior art, as represented for example by European Patent Aplications, EP 384070 A, EP 448297 A, EP 522726 A, EP 533392 A, EP 544492 A, EP 552053 A, and EP 552054 A has envisaged the use of enzymes in combination with small particle size zeolite MAP in laundry detergent compositions, none of these prior art documents specifically disclose the use of amylase enzyme with a small particle size zeolite MAP component. Furthermore, none of these prior art documents provides any teaching relating to the white residue deposit problem addressed by the current invention, nor of any solution thereto involving the selection of a particular enzyme.
According to the present invention there is provided a detergent composition containing
(a) a zeolite builder having a particle size, expressed as a d
50
value, of less than 1.0 micrometres;
(b) an amylase enzyme;
In a preferred aspect the zeolite builder comprises zeolite P having a silicon to aluminium ratio of not greater than 1.33 (zeolite MAP)
DETAILED DESCRIPTION OF THE INVENTION
Zeolite Builder
The first essential component of the present invention is an aluminosilicate zeolite builder, optionally in conjunction with one or more supplementary builders.
The zeolite builder is typically present at a level of from 1% to 80%, more preferably from 15% to 40% by weight of the compositions.
In an essential aspect the zeolite detergent builder has a particle size, expressed as a d
50
value of less than 1.0 micrometres, more preferably from 0.05 to 0.9 micrometres, most preferably from 0.2 to 0.7 micrometres.
The d
50
value indicates that 50% by weight of the particles have a diameter smaller than that figure. The particle size may, in particular be determined by conventional analytical techniques such as microscopic determination using a scanning electron microscope or by means of a laser granulometer.
Suitable aluminosilicate zeolites have the unit cell formula Na
z
[(AlO
2
)
z
(SiO
2
)
y
]. XH
2
O wherein z and y are at least 6; the molar ratio of z to y is from 1.0 to 0.5 and x is at least 5, preferably from 7.5 to 276, more preferably from 10 to 264. The aluminosilicate material are in hydrated form and are preferably crystalline, containing from 10% to 28%, more preferably from 18% to 22% water in bound form.
The aluminosilicate zeolites can be naturally occurring materials, but are preferably synthetically derived. Synthetic crystalline aluminosilicate ion exchange materials are available under the designations Zeolite A, Zeolite B, Zeolite P, Zeolite X, Zeolite MAP, Zeolite HS and mixtures thereof.
Zeolite A has the formula
Na
12
[AlO
2
)
12
(SiO
2
)
12
].xH
2
O
wherein x is from 20 to 30, especially 27. Zeolite X has the formula Na
86
[(AlO
2
)
86
(SiO
2
)
106
].276 H
2
O.
Zeolite MAP is described in EP 384070A (Unilever). It is defined as an alkali metal alumino-silicate of the zeolite P type having a silicon to aluminium ratio not greater than 1.33, preferably within the range from 0.9 to 1.33 and more preferably within the range of from 0.9 to 1.2.
Of particular interest is zeolite MAP having a silicon to aluminium ratio not greater than 1.15 and, more particularly, not greater than 1.07.
Zeolite P having a Si:Al ratio of 1.33 or less may be prepared by the following steps:
(i) mixing together a sodium aluminate having a mole ratio Na
2
O:Al
2
O
3
within the range of from 1.4 to 2.0 and a sodium silicate having a mole ratio SiO
2
:Na
2
O within the range of from 0.8 to 3.4 with vigorous stirring at a temperature within the range of from 25° C. to boiling point usually 95° C., to give a gel having the following composition; Al
2
O
3
:(1.75-3.5)SiO
2
:(2.3-7.5)Na
2
O:P(80-450)H
2
O;
(ii) ageing the gel composition for 0.5 to 10 hours, preferably 2 to 5 hours, at a temperature within the range of from 70° C. to boiling point, usually to 95° C., with sufficient stirring to maintain any solids present in suspension;
(iii) separating the crystalline sodium aluminosilicate thus formed, washing to a pH within the range of from 10 to 12.5, and drying, preferably at a temperature not exceeding 150° C., to a moisture content of not less than 5 Wt. %.
Preferred drying methods are spray-drying and flash drying. It appears that oven drying at too high a temperature may adversely affect the calcium binding capacity of the product under certain circumstances.
Commercial sodium metasilicate pentahydrate dissolved in water and commercial sodium silicate solution (waterglass) are both suitable silica sources for the production of zeolite P in accordance with the invention. The reactants may be added together in any order either rapidly or slowly. Rapid addition at ambient temperature, and slow addition at elevated temperature (90-95° C.) both give the desired product.
Vigorous stirring of the gel during the addition of the reactants, and at least moderate stirring during the subsequent ageing step, however, appear to be essential for the formation of pure zeolite P. In the absence of stirring, various mixtures of crystalline and amorphous materials may be obtained.
Zeolite MAP generally has a calcium binding capacity of at least 150 mg CaO per g of anhydrous aluminosilcate, as measured by the standard method described in GB 1473201 (Henkel). The calcium binding capacity is normally 160 mg CaO/g and may be as high 170 mg CaO/g.
Although zeolite MAP like other zeolites contains water of hydration, for the purposes of the present invention amounts and percentages of zeolite are expressed in terms of the notional anhydrous material.
The amount of water present in hydrated zeolite MAP at ambient temperature and humidity is generally about 20 wt. %.
Amylase
The second essential component of the compositions is an amylase enzyme, that is to s
Clare Jonathan Richard
Garnett Carolyn Jayne
Wauben Johan Juliaan Serafin
Cook C. Brant
Elhilo Eisa
Gupta Yogendra N.
Taffy Frank
The Procter & Gamble & Company
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