Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
1998-05-26
2001-10-16
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S427000, C510S446000, C510S452000
Reexamination Certificate
active
06303558
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a medium to high bulk density particulate detergent composition.
BACKGROUND
Traditionally, particulate detergent compositions have been manufactured by the spray drying process, in which a slurry of components such as anionic detergent active, builder material and optionally non-anionic detergent active is manufactured and then dried by atomising it and spraying it into a stream of air at high temperature. The spray-dried compositions are found in practice to have bulk densities less than 600 g/l. There are limits on the quantity of anionic detergent active that can be included due to the need to form a slurry before spray-drying. The resultant spray-dried granules may be used directly as a detergent composition or other components may be post-dosed, for example heat or moisture sensitive components, to provide a complete powder composition.
In recent years, a number of detergent powder manufacturing processes have been developed in which a spray-drying tower is not used. Such so called non-tower route (NTR) processes typically involve granulation of anionic detergent active and builder in a high or medium speed mixer/densifier, typically in the presence of a liquid binder such as water or non-anionic detergent active. High detergent active compositions having medium to high bulk densities (500-900 g/l) have been produced by such non-tower processes.
However, it has been found that such so called concentrated products may have unsatisfactory dispensing properties in wash water, particularly in automatic washing machines. Problems have been encountered such as poor dispersion of the powder into the wash water in the dispenser drawer of a washing machine. A gritty, viscous mass may remain in the dispenser drawer. Further, powder compositions entrained in the wash water may not break up and disperse adequately. Undissolved particles of powder compositions may remain in the wash water. These can adhere to clothes and cause local damage. For example, where the detergent composition contains bleach, an undissolved mass of composition can adhere to clothing and, due to the locally high concentration of bleach, damage the clothing. Undissolved powder composition can remain on the clothes after washing.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a detergent powder composition having a medium to high bulk density (a bulk density of at least 600 g/l) and a moderate to high anionic detergent active content.
The present inventors have discovered that the dispersion problems of particulate detergent compositions can be due to unfavourable properties of some of the components, such as anionic surfactant, or due to unfavourable interactions between different components which occur in the particles. The inventors have discovered that it is beneficial to concentrate the components having undesirable properties into a smaller number of particles. This entails providing particles of high concentration of the component which has the undesirable property. Further, it is desired to separate components which would show unfavourable interactions if they were included in the same particle.
Accordingly, the present invention provides a particulate detergent composition or component having a bulk density of at least 600 g/l and comprising at least 10% by weight (preferably at least 12% by weight) of organic detergent surfactant and from 10 to 70% by weight (preferably from 15 to 70% by weight) of detergency builder, the detergent composition or component being composed of at least two, and preferably at least three, granular components:
(i) granules comprising at least 60% by weight of anionic surfactant (“anionic surfactant granules”),
(ii) granules comprising at least 20% by weight of nonionic surfactant and less than 10% by weight aluminosilicate (“nonionic surfactant granules”), and
(iii) optionally, granules comprising up to 100% (preferably up to 90%) by weight of detergency builder and optionally from 0 to 10% of nonionic or anionic surfactant(“builder granules”).
The anionic surfactant granules (i) are preferably present in an amount of from 1 to 70% by weight.
The nonionic surfactant granules (ii) are preferably present in an amount of from 1 to 30% by weight of the composition, more preferably from 1 to 50% by weight.
The optional builder granules are preferably present in an amount of from 5 to 80% by weight, and more preferably in an amount of at least 15% by weight.
The composition limits on the individual granules according to the invention have been found to provide detergent compositions having surprisingly reduced problems of residues in the wash.
It has been found that there is a particularly disadvantageous interaction between nonionic surfactant and aluminosilicate builder, which leads to problems of residues in the wash discussed above. The composition of the present invention allows this problem to be overcome. Further, there can be problems due to unfavourable interaction between aluminosilicate builder and anionic surfactant. The effects of concentrating anionic surfactant in the anionic surfactant granule will be discussed further below.
The total quantity of detergent surfactant in the compositions of the invention is preferably at least 12% by weight, and the quantity of nonionic surfactant is preferably from 1 to 40% by weight, more preferably from 1 to 30% by weight.
The Anionic Surfactant Granules (i)
The anionic surfactant granules preferably comprise from 60 to 90% by weight of anionic surfactant.
The anionic surfactant granules may also contain nonionic surfactant. The anionic surfactant granules may also contain minor ingredients such as water, sodium carboxymethylcellulose, fluorescers, dyes, etc.
The anionic surfactant granules may optionally comprise from 0 to 40% by weight of detergency builder. The builder material may comprise soluble builder such as salts (preferably alkali metal salts, particularly preferably sodium salts) of tripolyphosphate, carbonate, silicate, sesquicarbonate, citrate or mixtures thereof, or burkeite (a double salt of sodium sulphate and sodium carbonate), NTA, polycarboxylic acid monomer, polycarboxylic acid polymer, polycarboxylic acid/maleic acid copolymer or mixtures thereof.
The builder may comprise insoluble builder such as aluminosilicate. The aluminosilicate may comprise zeolite, in particular zeolite MAP, zeolite 4A, amorphous aluminosilicate and mixtures thereof. It is particularly preferred, however, that the quantity of aluminosilicate builder is low. Preferably, aluminosilicate builder provides less than 15% by weight of the anionic surfactant particles, more preferably less than 10%.
The anionic surfactant granules may be manufactured by any suitable process. Preferably, such granules are manufactured by mixing the components in a high speed mixer to agglomerate the components. Suitable mixers will be discussed further below.
Processes for producing granules containing high quantities of anionic surfactant are set out in WO 96/06916A and WO 96/06917A (Unilever).
The method of WO 97/32002A (Unilever) is particularly preferred. In this method, a paste material comprising water and an anionic surfactant, or a mixture of acid surfactant precursor and alkaline neutralising agent, is fed into a drying zone, the paste material being heated in the drying zone to reduce the water content thereof and the paste material being subsequently cooled in a cooling zone to form detergent particles, a layering agent being introduced into the cooling zone during the cooling step. Alternatively, a paste material comprising water and an anionic surfactant, or a mixture of acid surfactant precursor and alkaline neutralising agent fed into a drying zone, the material being heated in the drying zone to reduce the water content thereof and the material being subsequently cooled in a cooling zone to form detergent particles, the material being treated in the cooling zone with a stream of cooling gas. This process can provide detergent particles comprising at least 60% by w
Emery William Derek
Farnworth Pauline
Hawkes Georgina
Instone Terry
Liem Seeng Djiang
Lever Brothers Co., division of Conopco
Mitelman Rimma
Ogden Necholus
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