Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1995-04-27
2002-05-21
Einsmann, Margaret (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S372000, C510S375000, C510S377000, C510S428000
Reexamination Certificate
active
06391839
ABSTRACT:
This invention relates to detergent compositions containing crystalline layered silicates , an alkali metal percarbonate bleach and ethylenediamine-N,N′-disuccinic acid or salts thereof.
Detergent compositions incorporating layered sodium silicates are known in the art, being disclosed in, for example, DE-A-3413571, DE-A-3812556 and EP-A-0337219. These disclosures teach that the layered crystalline forms of sodium silicate display superior mineral hardness sequestration ability relative to the corresponding silicate salts in amorphous form and are thus advantageous as detergent builder materials.
Laundry detergent compositions containing the nil-phosphorus chelant, ethylenediamine-N,N′-disuccinic acid (EDDS) are also known in the art, being disclosed in, for example, EP-A-0267 653. This disclosure teaches that EDDS when incorporated in such laundry compositions assists in the removal of food, beverage and certain other organic stains from fabrics during the laundry process. It also teaches that EDDS may be used as a replacement for all or part of the phosphonate chelants currently used in many existing laundry products.
Detergent compositions containing sodium percarbonate are known in the art. Sodium percarbonate is an attractive perhydrate for use in detergent compositions because it dissolves readily in water, is weight efficient and, after giving up its available oxygen, provides a useful source of carbonate ions for detergency purposes.
Considerable interest exists in the development of more ‘environmentally friendly’ detergent compositions and processes for washing laundry in the home. The term ‘environmentally friendly’ as applied to home wash processes has many connotations, but will include those processes which consume less energy, by operating at lower temperatures and/or using lower volumes of water. ‘Environmentally friendly’ detergent compositions are often characterised in that they minimize the levels of components which may cause environmentally undesirable effects. These components may include for example any components which contain phosphorus, which has been linked to undesirable effects in lakes and rivers, and any components which contain boron whose persistence in the environment is also of possible concern.
Detergent compositions of the so-called ‘compact’ type which are of higher bulk density and contain lower amounts of filler salts than conventional laundry detergent products also provide an environmental benefit in that these provide equivalent performance from a smaller volume of powder. Thus, comparable cleaning results may be obtained from a smaller box of compact product as from a larger box of conventional product and this allows a reduction in packaging requirements to be made.
The Applicants have now discovered that surprising stain removal benefits are obtained, particularly on bleachable and enzymatic stains, for a detergent composition comprising in combination a crystalline layered sodium silicate, alkali metal percarbonate bleach and EDDS. Detergent compositions comprising this zero phosphorus, zero boron, builder/bleach/chelant system may be formulated such that stain removal performance benefits are obtained even when reduced amounts in total of builder, bleach and chelant are used.
It is therefore an object of the present invention to provide detergent compositions comprising a zero phosphorus and boron containing builder/bleach/chelant system.
It is a further object of the present invention to provide detergent compositions which may be used at lower dosage level in a home laundry process.
According to the present invention there is provided a detergent composition comprising;
(a) from 1% to 80% by weight of a crystalline layered silicate builder material of formula LMSi
x
O
2x+1
.yH
2
O wherein L is an alkali metal, and M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20;
(b) from 3% to 40% by weight of an alkali metal percarbonate bleach;
(c) from 0.1% to 10% by weight of ethylenediamine-N,N′-disuccinic acid, or alkali metal, alkaline earth, ammonium or substituted ammonium salts thereof, or mixtures thereof.
Preferably, the compositions of the invention are free from any phosphorus or boron containing compounds.
The detergent compositions of the invention comprise three essential components, viz. the crystalline layered silicate, the alkali metal percarbonate bleach and the ethylenediamine-N,N′-disuccinic acid or salt thereof.
The crystalline layered silicate material has the general formula
LMSi
x
O
2x+1
.yH
2
O
wherein L is an alkali metal, preferably Na, and M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20. Crystalline layered sodium silicates of this type are disclosed in EP-A-0164514 and methods for their preparation are disclosed in DE-A-3417649, DE-A-3742043 and DE-A-3718350. For the purposes of the present invention, x in the general formula above has a value of 2, 3 or 4 and is preferably 2. More preferably M is sodium and y is 0 and preferred examples of this formula comprise the &agr;-, &bgr;-, &ggr;- and &dgr;- forms of Na
2
Si
2
O
5
. These materials are available from Hoechst AG FRG as respectively NaSKS-5, NaSKS-7, NaSKS-11 and NaSKS-6. The most preferred material is Na
2
Si
2
O
5
, NaSKS-6.
These materials are processed into free flowing solids with a particle size of from 150 to 1000 micrometers and preferably a bulk density of at least 800 g/liter preferably approximately 900 g/liter. However, as made, the crystals are fragile and break down easily into particles of size less than 100 micrometers.
In the granular detergent compositions of the present invention, the crystalline layered silicate comprises from 1% to 80% by weight of the composition, more preferably from 5% to 40% and most preferably from 7% to 20% by weight.
The crystalline layered silicate material is preferably present as a particulate in intimate admixture with a solid, water-soluble ionisable material. The solid, water-soluble ionisable material is selected from organic acids, organic and inorganic acid salts and mixtures thereof. The primary requirement is that the material should contain at least one functional acidic group of which the pKa should be less than 9, providing a capability for at least partial neutralisation of the hydroxyl ions released by the crystalline layered silicate. Surprisingly, it has been found for the purposes of the present invention, that the ionisable material need not have a pH <7 in solution, or be present in an amount capable of providing hydrogen ions in stoichiometric parity with the hydroxyl ions produced by dissolution of the crystalline silicate. In fact neutralisation of the ionisable material during storage of the particulate, whilst causing a loss in fabric damage benefit, does not eliminate it.
The ionisable material should also have a mean particle size not greater than 300 micrometers and preferably not greater than 100 micrometers. This facilitates uniform distribution of the ionisable material and the crystalline silicate and is believed to enhance localised pH reduction when the particulate dissolves in the wash liquor.
Suitable organic acids include ascorbic, citric, glutaric, gluconic, glycolic, malic, maleic, malonic, oxalic, succinic and tartaric acids, 1 hydroxy ethane 1,1-diphosphonic acid (EHDP), amino poly methylene phosphonic acids such as NTMP, EDTMP & DETPMP, and mixtures of any of the foregoing. Suitable acid salts include sodium hydrogen carbonate, sodium hydrogen oxalate, sodium hydrogen sulphate, sodium acid pyrophosphate, sodium acid orthophosphate, sodium hydrogen tartrate or mixtures of any of the foregoing.
The particulate mixture of crystalline layered silicate and solid water soluble ionisable material will have a pH of at least 10 (as measured on a 1% solution in 20° C. distilled water) and more usually will have a pH of at least 11, normally at least 11.5.
The incorporation of other ingredients additional to the crystalline layered silicate and ionisable water soluble comp
Addison Michael Crombie
Moss Michael Alan J.
Dressman Marianne
Einsmann Margaret
Miller Steven W.
The Procter & Gamble & Company
William Zerby Kim
LandOfFree
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