Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1999-06-04
2000-07-11
Douyon, Lorna M.
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
510298, 510361, 510441, 510442, 510446, 510470, 510477, 510488, 510491, C11D 320, C11D 1100, C11D 1700
Patent
active
060873116
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to coated detergent tablets, especially those adapted for use in washing machines, and to processes for making the coated detergent tablets.
Although cleaning compositions in tablet form have often been proposed, these have not (with the exception of soap bars for personal washing) gained any substantial success, despite the several advantages of products in a unit dispensing form. One of the reasons for this may be that detergent tablets require a relatively complex manufacturing process. In particular, it is often desirable to provide the tablet with a coating and this adds to the difficulties of manufacture.
While tablets without a coating are entirely effective in use, they usually lack the necessary surface hardness to withstand the abrasion that is a part of normal manufacture, packaging and handling. The result is that uncoated tablets suffer from abrasion during these processes, resulting in chipped tablets and loss of active material.
Finally, coating of tablets is often desired for aesthetic reasons, to improve the outer appearance of the tablet or to achieve some particular aesthetic effect.
Numerous methods of tablet coating have been proposed, and many of these have been suggested for detergent tablets. However, all of these methods have certain disadvantages, as will be explained below.
GB-A-0 989 683, published on Apr. 22, 1965, discloses a process for preparing a particulate detergent from surfactants and inorganic salts; spraying on water-soluble silicate; and pressing the detergent particles into a solid form-retaining tablet. Finally a readily water-soluble organic film-forming polymer (for example, polyvinyl alcohol) provides a coating to make the detergent tablet resistant to abrasion and accidental breakage.
EP-A-0 002 293, published on Jun. 13, 1979, discloses a tablet coating comprising hydrated salt such as acetate, metaborate, orthophosphate, tartrate, and sulphate.
EP-A-0 716 144, published on Jun. 12, 1996, also discloses laundry detergent tablets with water-soluble coatings which may be organic polymers including acrylic/maleic co-polymer, polyethylene glycol, PVPVA, and sugar.
WO9518215, published on Jul. 6, 1995, provides water-insoluble coatings for solid cast tablets. The tablets are provided with hydrophobic coatings including wax, fatty acid, fatty acid amides, and polyethylene glycol.
None of the prior art discloses the use of dicarboxylic acid coating materials for tablets that have a soft core prepared by compression of particulate materials.
The present invention provides a means by which tablets with a core which is formed by compressing a particulate material, the particulate material comprising surfactant and detergent builder, can be provided with a hard, thin, coating so that they can be stored, shipped and handled, but the coating is broken when the tablet is in the washing machine exposing the soft core which breaks up easily and rapidly, releasing the active ingredients into the wash solution.
The object of the present invention is to provide a tablet which completely disintegrates and disperses in alkaline or surfactant-rich solutions such as the wash liquor.
SUMMARY OF THE INVENTION
The object of the invention is achieved by providing a coating comprising a dicarboxylic acid, preferably wherein the length of the carbon chain of the dicarboxylic acid is from C2 to C13.
In one embodiment of the invention the coating consists essentially of dicarboxylic acid.
In a further aspect of the invention there is provided a process for making a tablet comprising the steps of: material comprising surfactant and detergent builder; the form of a melt;
In an alternative to this embodiment of the invention there is provided a process for making a tablet comprising the steps of: material comprising surfactant and detergent builder; dissolved in a solvent or water;
DETAILED DESCRIPTION OF THE INVENTION
Tablets to be coated in the present invention can be prepared simply by mixing the solid ingredients together and compressing the mixture in
REFERENCES:
patent: 3324038 (1967-06-01), Chaffee et al.
patent: 3506756 (1970-04-01), Hoss
patent: 4576727 (1986-03-01), Browne
patent: 5133892 (1992-07-01), Chun et al.
Cook C. Brant
Douyon Lorna M.
Rasser Jacobus C.
The Proctor & Gamble Company
Zerby Kim William
LandOfFree
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