Solid detergent compositions comprising sesquicarbonate

Details Solid detergent compositions comprising sesquicarbonate Solid detergent compositions comprising sesquicarbonate

2001-08-07

2003-10-07

Ogden, Necholus (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

Solid, shaped macroscopic article or structure

C510S446000, C510S447000, C510S450000, C510S392000, C510S509000

Reexamination Certificate

active

06630439

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 generally preferred that the compositions are free of phosphate-containing builder material.
The inventors have undertaken detailed studies of these properties of detergents and have found that the factors influening these properties are numerous and inter-related in a complex way: inorganic compounds in a detergent formulation can affect the phase chemistry of surfactants via their contribution to the ionic strength of the solution, certain surfactant phases can trap inorganic species in a phase that is conducive to hydrate formation; certain inorganic hydrates, once formed, can interlock with each other and produce a tough framework that is persistent and provides micro-regions that are conducive to surfactant phase formation. Further complicating this situation is the fact that many of the inorganic hydrates and surfactant phases are affected by the concentration of the detergent in water by the hardness of the water and by the temperature of the water Thus nothing is known in the art that quantitatively describes this complex situation and leads to a solution for providing detergent compositions which will avoid such problems. The inventor s have now surprisingly found that a thorough understanding of these complex inter-related factors has enabled them to provide detergent compositions avoiding the problems discussed above. Novel detergent compositions are therefore provided which have a specified Grand Compatibility Index.
Thus, novel detergent compositions result which provide good washing performance with minimum amounts of detergent and good detergent delivery into the wash are achieved and fabric damage due to high localised bleach concentrations is minimised.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a solid detergent composition comprising from 8-60 wt %. of a surfactant system and having a minimum Grand Compatability Index of 0.5, preferably 0.6, more preferably 0.7 or even 0.8 or 0.9.
The Grand Compatability Index is a function of a Compatability Index and a Secondary Compatibility Index.
The Compatibility Index can be determined in the following way:
1 liter of de-ionised water is placed in a tergitometer (Erweka DT6-R hereinafter referred to as the ‘Sotax’ apparatus) (USP 711 dissolution standard). Adjust the hardness to 100 ppm equivalent of CaCO
3
using a convenient soluble form of calcium, such as calcium chloride. 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 center 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-permeable lid is used to close off the top of the wire basket. The quantity of sample is gravimetrically determined by weight difference. 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 transferred to a sealed container.
Analyze the residue in the sealed container in its entirety for the number of moles of the hydrated and anhydrous forms of any carbonate, sulfate, borate, and phosphate salts. This is accomplished by using any of the standard techniques known to those skilled in the art of detergent analysis. It will be appreciated that this analysis is to be conducted immediately so that the salts will not change their hydration states prior to the analysis.
The water remaining in the Sotex apparatus is also analyzed in its entirety. First it is filtered through a 0.45 micron filter and analyzed for the number of moles of carbonate, sulfate, borate, and phosphate ions. It will be appreciated that this filtration should be accomplished immediately to avoid formation of insoluble salts from the soluble salts in the solution. The filtered solution should be analyzed for the number of moles of any carbonate, sulfate, borate, and phosphate ions that are in solution. All carbonate, sulfate, borate, and phosphate salts that may have precipitated from the solution after the filtration are also analyzed and are added to the numbers that were found to be in solution.
The Compatibility Index is calculated according to the following formulae:
Residue Index=(
I
s
+I
8h
+O
o
*(
I
o
−I
8h
)/(
I
o
+O
o
)
where:
I
s
=number of moles of the above mentioned inorganics (carbonate, sulfate, borate and phosphate) ions determined in the aqueous solution;
I
8h
=number of moles of the above mentioned inorganic hydrate salts containing less than 8 moles of water of hydration per mole determined in the wire basket residue;
I
8h
=number of moles of the above mentioned inorganic hydrate salt s containing more than 8 moles of water of hydration per mole determined in the wire basket residue;
I
o
=number of moles of the above mentioned inorganic salts that were placed in the wire basket at the start of the experiment;
O
o
=number of moles of anionic, nonionic, cationic and semipolar surfactants (as described in below) that were placed in the wire basket at the start of the experiment,
The Secondary Compatibility Index is determined in the following way:
25 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. Adjust the hardness to 100 ppm equivalent of CaCO
3
using a convenient and a soluble form of calcium such as calcium chloride. 2 grammes of product is then added to the water and stirred at a stirrer speed of 200 rpm for 20 minutes, After 20 minutes, the water containing the detergent sample is filtered through a 0.45 micron filter. The solids collected on the filter are analyzed using the same procedure as described above in the Compatibility Index det

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