Bleaching and dyeing; fluid treatment and chemical modification – Cleaning or laundering
Reexamination Certificate
2002-10-10
2003-10-28
Douyon, Lorna M. (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Cleaning or laundering
Reexamination Certificate
active
06638320
ABSTRACT:
TECHNICAL FIELD
The present invention relates to detergent compositions in non-particulate form. More particularly, the invention relates to a process for improving the dispersibility of a non-particulate detergent composition, e.g., tablet, block or bar, in water, by enabling the manufacture of a non-particulate detergent product that sinks in water and rapidly disintegrates and dissolves in water
BACKGROUND OF THE INVENTION
Non-particulate detergents are an alternative to granular or particulate forms of detergents for simplifying the dosing of such detergents for automatic washing machines, such as laundry or dishwashing machines. Such non-particulate detergents are usually supplied in the form of bars, tablets or briquettes. Such non-particulate detergents not only prevent spillage of the detergent composition but also eliminate the need for the consumer to estimate the correct dosage of the detergent composition per wash. Further, such non-particulate detergents also minimize the contact by the consumer with the detergent.
An important factor for successful performance of a non-particulate detergent is its ability to dissolve in the washing machine in a controlled manner according to a desired dissolution profile during the program cycle of the machine. Another important performance factor is that the non-particulate detergent should be hard enough to facilitate easy handling of the detergent prior to use, so that it does not inadvertently lose its structure, crumble, or deteriorate, both during the packaging, transport and storage and during handling by the end consumer prior to actual use. Such performance aspects are an important feature of the non-particulate detergent, and although they are not necessarily the focus of the present invention, they are inherently a part of the background of the present invention.
Additionally, a very desirable feature of a non-particulate detergent, such as for example, a tablet, is its ability to sink in water and rapidly disperse in water to form a wash solution. In order to sink in water, a detergent tablet must have a density greater than 1000 g/l and in order to disperse in water, a detergent tablet must be able to break up in water. However, when laundry tablets are made from low bulk density detergents, such as those made by spray dried processes, wherein the detergent powder has a bulk density less than about 650 g/l, the problem frequently encountered is that the force required to compact the detergent powder into tablets having a density of at least 1000 g/l is so high that the detergent tablets do not readily disperse in water. This problem is further escalated by the fact that detergent powders made from spray dried processes tend to be more porous and sticky. Thus when these detergent powders are pressed into tablets having a density of at least 1000 g/l, the powder particles stick together and consequently the tablet does not readily break up and dissolve in water. Conversely, if the tablets made from low bulk density detergent powders are compacted using a lower force, they generally disperse in water but at a slower rate because they have a density less than 1000 g/l and thus tend to float in water before fully dispersing in water.
The above problem is usually not encountered when making detergent tablets from a detergent powder made by agglomeration processes because detergent powders made by agglomeration processes usually have a bulk density in a range of about 700 g/l to about 850 g/l and consequently, the force required to compress the powder into a tablet having a density of at least 1000 g/l is not so high. Thus detergent tablets made by compacting detergent powders made from agglomeration process usually sink in water. However, agglomeration process detergents or “agglomerates”, which inherently have higher density than spray dried process detergents or “spray dried granules”, generally exhibit slower dissolution rates in water, as compared to spray dried granules.
Thus the production of detergent tablets is a complex matter. It involves more than the mere selection of components or the compression of a particular detergent composition into a tablet. The tablet must be capable of withstanding the shocks of packaging, handling and distribution without crumbling. In other words the tablet must be strong. But the tablet must also have a satisfactory rate of disintegration when immersed in water. The tablets known so far have generally shown too long a disintegration time, in favor of their strength, or they have had a very low strength, in favor of their shorter disintegration time.
It is highly desirable to have a laundry detergent tablet with a core which is formed by compressing a particulate material which has a detersive surfactant and a builder and wherein the particulate material is processed in a manner so as to make the individual particles sticky enough to stay together when the material is compressed into a tablet form, yet not too sticky to not disintegrate rapidly when immersed in water. This becomes a very challenging problem in light of the additional desirable requirement that the detergent tablet, after compaction, have a density of at least 1000 g/l so that it sinks in water.
This kind of a tablet performance has heretofore not been available and this level of performance requires not only careful selection of the type of detergent that makes up the core, but also requires novel ways to surface treat the detergent particles prior to compaction so as have just the right amount of stickiness. The present invention overcomes the problems as outlined above.
BACKGROUND ART
The prior art is replete with methods of forming tablets and coating tablets.
One approach has been to use acetate salt to improve the dissolution rate of detergents compressed in the form of tablets. EP-A-0002293, published on Jun. 13, 1979, discloses detergent tablets containing hydrated salt. The preferred hydrate salt is a mixture of sodium acetate trihydrate and sodium metaborate tetrahydrate.
Another approach known in the art is to use effervescent aids to improve tablet disintegration. CA-A-2040307 discloses laundry detergent tablets comprising anionic surfactants mixed with sodium carbonate and citric acid.
As far as coated tablets are concerned, 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.
European publication, 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. Another European publication, 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.
SUMMARY OF THE INVENTION
The invention meets the needs above by providing a process for producing a water-dispersible non-particulate detergent product. Specifically, in one aspect of the present invention, the process comprises the step of providing a particulate detergent composition. The process further includes the step of adding a flow aid to the particulate detergent composition in a range of from about 0.1% to about 25% by weight of the particulate detergent composition. The process then includes the step of compacting the particulate detergent composition having the flow aid by applying a pressure in an amount sufficient to form the water-dispersible non-particulate detergent product having a density of at least about 1000 g/l.
In another aspect of the present invention, a method of laundering fabric materials in a washing machine is provided. The method includes the steps of providing a flexible porous bag adapted fo
Angell Adrian John Waynforth
Zorb Les Charles
Corstanje Brahm J.
Douyon Lorna M.
Miller Steven W.
The Procter & Gamble & Company
William Zerby Kim
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