Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2000-05-24
2002-06-04
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Solid, shaped macroscopic article or structure
C510S224000, C510S294000, C510S298000, C510S330000, C510S514000, C510S515000, C008S137000
Reexamination Certificate
active
06399564
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a detergent tablet comprising a compressed portion and a non-compressed portion wherein the compressed portion dissolves at a faster rate than the non-compressed portion and the non-compressed portion comprises a finishing additive.
BACKGROUND
Detergent compositions in tablet form are known in the art. It is understood that detergent compositions in tablet form hold several advantages over detergent compositions in particulate form, such as ease of handling, transportation and storage.
Detergent tablets are most commonly prepared by pre-mixing components of a detergent composition and forming the pre-mixed detergent components into a tablet using a tablet press. Tablets are typically formed by compression of the detergent components into a tablet. However, the Applicant has found that some components of a detergent composition are adversely affected by the compression pressure used to form the tablets. These components could not previously be included in a detergent tablet composition without sustaining a loss in performance. In some cases the components may even have become unstable or inactive as a result of the compression.
Furthermore as the components of the detergent composition are compressed, the components are brought into close proximity with each other. A result of the close proximity of the components can be that certain of the components react with each other, becoming unstable, inactive or exhausted. A solution to this problem, as seen in the prior art, has been to separate detergent components that may potentially react with each other, especially when the components are compressed into tablet form. Separation of the components has been achieved by, for example, preparing multiple-layer tablets wherein the components that may potentially react with each other are contained in different layers of the tablet. Multiple-layer tablets, are traditionally prepared using multiple compression steps. Layers of the tablet that are subjected to more than one compression step are subjected to a cumulative and potentially greater overall compression pressure. An increase in compression pressure is known to decrease the rate of dissolution of the tablet with the effect that the multiple layers may not dissolve satisfactorily in use.
Other methods of achieving separation of detergent components have been described. For example EP-A 0,224,135 describes a dishwashing detergent in a form which comprises a warm water-soluble melt, into which is pressed a cold water-soluble tablet. The document teaches a detergent composition that consists of two parts, the first part dissolving in the pre-rinse and the second part dissolving in the main wash of the dishwasher.
EP-B-0,055,100 describes a lavatory block formed by combining a slow dissolving shaped body with a tablet. The lavatory block is designed to be placed in the cistern of a lavatory and dissolves over a period of days, preferably weeks. As a means of controlling the dissolution of the lavatory block, the document teaches admixing one or more solubility control agents. Examples of such solubility control agents are paradichlorobenzene, waxes, long chain fatty acids and alcohols and esters thereof and fatty alkylamides.
The Applicant has found that by providing a detergent tablet comprising a compressed portion and a non-compressed portion detergent components previously considered to be unacceptable for detergent tablets, can be incorporated into a detergent tablet. In addition, potentially reactive components of the detergent composition can be effectively separated.
A further advantage of using a detergent tablet as described herein, is the performance benefits which may be achieved in being able to prepare a detergent tablet where the compressed portion has a faster rate of dissolution than the non-compressed portion
SUMMARY OF THE INVENTION
According to the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein:
a) the compressed portion comprises a mould and dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein; and
b) the non-compressed portion is at least partially retained with the mould.
In another aspect of the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein and wherein the density of the non-compressed portion is at least 0.2 g/cm
3
less than the density of the compressed portion.
In yet another aspect of the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein:
a) the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein; and
b) the non-compressed portion is metasilicate-free.
In yet another aspect of the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein:
a) the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis, measured using the SOTAX dissolution test method described herein; and
b) the non-compressed portion comprises a finishing additive which is selected from the group consisting of organic polymeric compound, co-builder, enzyme, oxygen releasing bleach, bleach precursor or catalyst, surfactant, crystal growth inhibitor, bleach-destroying agent.
In yet another aspect of the present invention there is provided a detergent tablet comprising a compressed portion and a non-compressed portion wherein:
a) the compressed portion dissolves at a faster rate than the non-compressed portion on a weight by weight basis measured using the SOTAX dissolution test method described herein; and
b) the non-compressed portion comprises a finishing additive which is a fabric softener or a rinse aid.
DETAILED DESCRIPTION OF THE INVENTION
The compressed portion of the present invention dissolves at a faster rate than the non-compressed portion on a weight by weight basis as measured by the Sotax dissolution test method outlined below. This difference in rate of dissolution means that components of the compressed and non-compressed portions can be delivered to the wash water at different points in the washing or rinsing cycle of the washing machine.
For the purposes of the present invention the compressed portion has a faster dissolution rate than the non-compressed portion meaning that the components of the compressed portion will be delivered to the wash water before the components of the non-compressed portion. In another aspect of the present invention, the non-compressed portion dissolves at a temperature of less than 30° C. The compressed portion of the detergent tablet will begin to dissolve immediately on contact with water. Preferably at least 60%, more preferably at least 80%, most preferably at least 95% of the compressed portion dissolves in deionised water at 50° C. within 12 minutes.
The non-compressed portion comprises at least one finishing additive as described later. Finishing additives are components that provide either a cleaning benefit e.g. enzyme, a soil anti-redeposition benefit e.g. organic polymeric compound or drainage benefit e.g. nonionic surfactant. The non-compressed portion also begins to dissolve on contact with water, although the slower dissolution rate of the non-compressed portion is such that less than 40%, preferably less than 20%, most preferably less than 10% or even 5% of the non-compressed portion dissolves in deionised water at 50° C. within 12 minutes.
In an alternative embodiment of the present invention the non-compressed portion dissolves in the rinsing cycle of the washing machine. In this embodiment the finis
Painter Jeffrey Donald
Speed Lynda Anne
Bolam Brian
Douyon Lorna M.
The Procter & Gamble & Company
Waugh Kevin L.
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