Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2001-07-11
2004-01-06
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Solid, shaped macroscopic article or structure
C510S315000, C510S323000, C510S377000, C510S426000, C510S438000, C510S441000, C510S443000, C510S444000, C510S445000, C510S446000, C510S450000, C510S507000, C510S511000, C510S532000
Reexamination Certificate
active
06673766
ABSTRACT:
TECHNICAL FIELD
The invention relates to detergent compositions in particular, to laundry detergent compositions.
BACKGROUND
All detergents for laundry applications contain surfactants and builders. Generally, most detergents comprise a base powder made by spray-drying or by granulation of builder components and surfactant components for example, by agglomeration or extrusion. The base powder is often further treated with post-treatment steps such as dry-adding additional particulate detergent components, spray-on of further liquid components such as surfactants, particularly non-ionic surfactants and/or post-dusting steps using finely particulate solid materials to reduce caking and stickiness of the solid detergents produced.
Environmental pressures have led to the need to produce detergents which are as efficient as possible. The trend to use lower amounts of more highly compact detergent compositions, for example having a density above 600 g/l or 650 g/l or above 700 g/l or even higher, has emphasised the need to ensure full performance of all of the detergent components in the wash.
However, solid detergents tend to form lumps or gel upon contact with water. Lumps of gelled material may then fall into the sump of a washing machine where they are not disturbed mechanically, or because of their method of use in a machine, solid detergents do not dissolve, poor delivery of the product from a dispensing drawer of a washing machine or from a dispensing device and/or once in the machine itself results. Poor use of all of the detergent components is therefore achieved.
The inventors have found that in order to overcome this problem a combination of properties is required. This can be achieved by control of the detergent and the detergent making process so that the combinations of different detergent components, when formed into particulates for making finished detergent are modified so that the maximum performance benefit for each of the detergent components is achieved. This results in detergent compositions which have good solubility and minimum gelling and therefore maximum delivery of the detergent components to the wash, for example, by minimising the interaction of some detergent components and maximising the interaction between other detergent components. These benefits lead to good washing performance and minimising of any fabric damage due to high localised bleach concentrations.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a solid detergent composition comprising from 10-60 wt % of a surfactant system and having a maximum Residues Index of 25 and a maximum Secondary Residues Index of 15.
The Residues Index can be calculated in the following way:
1 litre of de-ionised water is placed in a tergitometer (Erweka DT6-R hereinafter referred to as the ‘Sotax’ apparatus) (USP 711 dissolution standard). The Sotax is fitted with a perspex lid to prevent evaporation, it is calibrated to a temperature of 5° C. with the stirrer (paddle) set to 200 rpm. The paddle has two blades fixed at the central axis directly opposite one another so that overall the two blades provide the paddle with a diameter of 75 mm. The paddle is positioned in the centre of the Sotax apparatus with a distance between the bottom of the paddle and the bottom of the tergitometer of 25 mm. The overall height of the paddle blades is 19 mm. A wire basket is provided having side walls and base formed from 20 mesh (850 &mgr;) stainless steel wire, a diameter of 25 mm and a height of 41 mm. The wire basket is filled with a detergent product, the surface of the detergent product is levelled off and a non-permneable lid is used to close off the top of the wire basket. The wire basket is then suspended in a stationary position midway between the central axis of the Sotax and the side wall, at a height such that the base of the wire basket is 7 mm above the upper surface of the paddle.
After twelve minutes the wire basket assembly is removed from the Sotax apparatus and the residue is removed to a pre-weighed container. The transfer step must be quantitative; a rinsing step with de-ionised water is acceptable if needed. The residues are oven dried at 70-80° C. until no further weight loss is recorded. The dry residue weight is recorded. The percentage residue from the basket as a proportion of the mass of the initial sample of the detergent composition which was placed into the Sotax is then calculated. An average of the percentage residue remaining for two identical samples provides the Residues Index number.
The Residues Index for the detergent compositions of the invention must be no greater than 25, preferably being no greater than 20, even more preferably being no greater than 15.
The Secondary Residues Index is calculated in the following way:
Using the same apparatus, 800 ml of de-ionised water is charged to the Sotax apparatus and the temperature is allowed to equilibrate to 20° C. with a stirrer speed of 200 rpm. 2 grammes of product is then added to the de-ionised water and stirred at a stirrer speed of 200 rpm for 20 minutes. After 20 minutes, the de-ionised water containing the detergent sample is filtered through a C70 black fabric circle (from Empirical Manufacturing Company) placed in a Buchner funnel with the smooth side of the fabric uppermost. The black fabric is removed from the Buchner funnel and placed on a sheet of paper. The black fabric is allowed to dry at ambient temperature for 24 hours. Three replicates are obtained for each test and an average of the percent residue remaining on the black fabric circle as a proportion of the total detergent sample charged to the Sotax, is calculated.
The average residues from the three replicates provide the Secondary Resides Index number, which must be a maximum of 15. Preferably, the maximum Secondary Residues Index is 10, even more preferably, the maximum Secondary Residues Index may be 5 or less.
Builder System
The detergent compositions comprise a builder system which may be provided by one or mixtures of more than one builder. Water soluble and/or water insoluble builders may be used. The builder system generally comprises from 1 to 90 wt % of the detergent composition, preferably from 20 to 80 wt % of the composition.
Water-soluble or Partially Water-soluble Builders
The builder system in the compositions according to the invention preferably contains a water-soluble and/or partially water-soluble builder compound, typically present at a level of from 1% to 80% by weight, preferably in amounts up to 50 wt %, or up to 40% or even 35%. Preferably water-soluble builders are present in amounts from at least 3% or 8%, but they are preferably present in amounts from 6 to 25 wt %.
The detergent compositions of the invention may comprise phosphate-containing builder material, such as tetrasodium pyrophosphate or more preferably anhydrous sodium tripolyphosphate. Phosphate builders may be present at a level of from 0.5% to 60%, or from 5% to 50%, or even from 8% to 40% by weight. However, it is generally preferred that the compositions are free of phosphate-containing builder material.
Crystalline layered silicates are also suitable partially water-soluble builders. The preferred crystalline layered silicate herein has the general formula
NaMSi
x
O
2x+1
.y
H
2
O
wherein 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 and DE-A-3742043. For the purpose of the present invention, x in the general formula above has a value of 2, 3 or 4 and is preferably 2. M is preferably H, K or Na or mixtures thereof, preferably Na. The most preferred material is &agr;-Na
2
Si
2
O
5
, &bgr;-Na
2
Si
2
O
5
or &dgr;-Na
2
Si
2
O
5
, or mixtures thereof, preferably being at least 75% -Na
2
Si
2
O
5
, for example available from Clariant as NaSKS-6. The crystalline layered silicate material, in particular of the formula Na
2
Si
2
O
5
may optionally comprise other
Alam Zayeed
Baillely Gerard Marcel
Bohlen David Scott
Brooker Alan Thomas
Canceil Sylvestre
Boyer Charles
Corstanje Brahm J.
Glazer Julia A.
The Procter & Gamble & Company
Zerby Kim W.
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