Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2000-05-24
2001-10-16
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, C510S298000, C510S441000
Reexamination Certificate
active
06303561
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a detergent tablet comprising a compressed portion comprising compressed detergent components and a cavity and a non-compressed portion wherein the non-compressed portion is retained within the cavity provided by the compressed portion.
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, 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 such multiple layer 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 that has a faster rate of dissolution versus conventional detergent tablets known in the prior art of equivalent dimensions. It is believed that the performance benefits are achieved because the components of the detergent tablet are delivered to the wash at a faster rate.
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 at least one compressed detergent component and a cavity extending from a first external surface of the compressed portion to a second external surface of the compressed portion; and
b) the non-compressed portion is retained within said cavity.
DETAILED DESCRIPTION OF THE INVENTION
Compressed Portion
The compressed portion of the detergent tablet comprises at least one compressed detergent component, but preferably a comprises a mixture of compressed detergent components. Any detergent component conventionally used in known detergent tablets is suitable for incorporation into the compressed portion of the detergent tablets of this invention. Suitable detergent components are described hereinafter. Preferred detergent components include builder compound, surfactant, bleaching agent, bleach activator, bleach catalyst, enzyme and an alkalinity source.
The detergent components are preferably prepared in particulate form (i.e. powder or granular form) and may be prepared by any known method, for example conventional spray drying, granulation or agglomeration. The detergent component(s) are premixed and then compressed using any equipment suitable for forming compressed tablets, blocks, bricks or briquettes; described in more detail hereafter.
The compressed portion of the present invention is prepared such that it comprises a cavity which extends from one external surface of the compressed portion to a second external surface of the compressed portion. The method of preparation of the compressed portion is described in more detail later.
Non-Compressed Portion
The non-compressed portion of the present invention is retained within a cavity provided by the compressed portion such that it is substantially exposed at a first external surface and a second external surface of the compressed portion. The non-compressed portion may partially, but preferably substantially fills the cavity provided by the compressed portion.
In a preferred aspect of the present invention the compressed portion and the non-compressed portion have different rates of dissolution, more preferably the non-compressed portion dissolves at a faster rate than the compressed portion. The exposure of the non-compressed portion at a first and a second external surface of the compressed portion means that a greater surface area of the components of the non-compressed portion are exposed to the wash water. The exposure of a greater surface area means that the components of the non-compressed portion of the present invention will dissolve and therefore be delivered to the wash water at a faster rate than components of a non-compressed portion that is exposed at only one external surface of the compressed portion or components of a detergent tablet known in the art.
In addition to the above, as the non-compressed portion dissolves it exposes greater surface area of the compressed portion to the wash water resulting in an increase in rate of dissolution of the compressed portion versus detergent tablets known in the art of comparable dimensions. Preferably the non-compressed portion dissolves in water at less than 30° C.
In one aspect of the present invention, the non-compressed portion comprises a first and a second and optionally subsequent non-compressed portions. In this aspect it is preferred that the first non-compressed portion and the second non-compressed and optionally subsequent non-compressed portions have different rates of dissolution.
The non-compressed portion preferably comprises one or more detergent components as described hereinafter. The non-compressed portion and/or components of the non-compressed portion may be in particulate (i.e. powder or granular), gel or liquid form. The non-compressed portion in addition to comprising a detergent component, may also optionally comprise a carrier component. The non-compressed
Douyon Lorna M.
Hasse Donald E.
Miller Steven W.
The Procter & Gamble Co.
Zerby Kim W.
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