Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2000-01-18
2002-01-15
Kopec, Mark (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Solid, shaped macroscopic article or structure
C510S296000, C510S298000, C510S349000, C510S396000, C510S438000, C510S440000, C510S441000, C510S445000, C510S447000, C510S449000
Reexamination Certificate
active
06339059
ABSTRACT:
The present invention is concerned with detergent compositions in the form of tablets. These tablets may be for the purpose of fabric washing in a laundry washing machine, for dish washing in a mechanical dish washer or for some other cleaning function.
It is desirable that tablets should have adequate mechanical strength when dry, before use, yet disintegrate and disperse/dissolve quickly when added to wash water. It has not proved simple to achieve both properties simultaneously. As more pressure is used when a tablet is compacted, so the tablet density and strength rise, but the speed of disintegration/dissolution when the tablet comes into contact with wash water goes down.
Tablets of detergent composition may be “homogenous” tablets in which the entire tablet consists of a single composition compacted into tablet form. However the present invention is concerned with “heterogenous tablets” in which the tablet is subdivided into more than one separate region and is made from more than one composition. Tablets which are “heterogenous” in that they are subdivided into two layers have been marketed commercially.
The use of swelling disintegrants to enhance the disintegration rate of one region of a detergent tablet relative to another region was disclosed in our WO 98/55590, wherein a higher concentration of water-insoluble swelling disintegrant in one region compared to another region, caused the former region to dissolve/disperse faster than the latter region.
It has now been found that by making the inner region of a detergent tablet swell to a greater extent than the regions surrounding it, the rate of dissolution/dispersion of the whole tablet can be improved.
Accordingly, the present invention provides a detergent tablet having at least two discrete regions each compacted from particulate composition, wherein a first said region consists of a compacted particulate composition containing swelling disintegrant such that the region increases in volume on contact with water, and in at least one direction through said region is flanked on both sides by one or more other regions which swell to a lesser extent on contact with water than said first region.
It is preferred that the one or more other regions contain a lower concentration of swelling disintegrant than the first region, or no swelling disintegrant at all. The ratio of concentrations of swelling disintegrant between the first region, and the one or more other regions is at least greater than 1:1, preferably greater than 3:1 or even 7:1.
In particular, if the one or more other regions contain the same swelling disintegrant which is in the first region, then the concentration of said swelling disintegrant is lower in the one or more other regions than in the first region.
However, it is also envisaged that the one or more other regions may contain an equal or greater concentration of swelling disintegrant than the first region, but in this case the swelling disintegrant or disintegrants in the one or more other regions will have a lower swelling capacity than the swelling disintegrant in the first region. The ratios of swelling capacity between the first region, and the one or more other regions is at least greater than 1:1, preferably greater than 3:1 or even 7:1.
Tablet Forms
The invention encompasses a number of tablet forms are these are discussed below.
In one form, the tablet has a pair of opposite faces spaced apart from each other and joined by a peripheral surface of the tablet, wherein said first region provides a first part of a said face and said one or more further regions provide an adjoining part of said face.
The said face may be substantially flat, or the arrangement may be such that the first part of the face is not at the same level as the adjacent part(s), so that there is a step at the junction of the parts. Even if the two parts are at substantially the same level there is likely to be a groove, a slight step or a line in the surface at their junction.
The first part may stand out from the adjacent part of the end face or it may be inset from the adjacent part of the end face.
Preferably the first region is a core which is entirely surrounded by said one or more other regions of the tablet. A single such surrounding region may provide the entire peripheral surface of the tablet and the remainder of the tablet end faces. Other arrangements are conceivable. A region surrounding a core might possibly be split into two or more, such as three, layers, and the core could itself have two layers.
In a preferred arrangement the first region extends through the tablet so as to be visible at both faces, and may be inset from the surrounding part of each face. Another possibility is that such a region could be visible as part of one face yet extend only part way through the tablet, so that subdivision into regions would not be visible at the opposite face of the tablet.
An alternative arrangement is where the first region extends across the whole width of the tablet, such that the first region forms part of the peripheral surface of the tablet.
A region such as a core which provides a first part of a tablet face adjoined or surrounded by a larger second part of the face, is likely to constitute from 10% or 15% up to 35% or 40% of the tablet weight and from 10% or 15% up to 35% or 40% of the area of the tablet face.
One particularly preferred method of making such tablets comprises the steps of:
introducing at least one particulate composition into a mould cavity around a plunger which projects into or through the cavity, followed by driving at least one punch onto the compositions around the plunger in the cavity, thereby compacting them into an outside zone of the tablet
withdrawing the plunger from within the compacted compositions, introducing a further particulate composition into the space vacated by the plunger, and urging at least one plunger against the composition introduced into this space, so as to compact it into an inner zone of the tablet.
There is no need to apply any substantial compaction pressure to the compositions in the outer zone when compacting the further composition, thus allowing the compaction pressure applied to each of the two zones of the tablet to be chosen independently. However, some light pressure may be applied to the (already compacted) compositions in the outer zone to hold them steady while the further composition in the inner zone is compacted.
Preferably the process is carried out using a pair of punches which are relatively movable towards each other within the mould cavity and away from each other, wherein each punch encloses or at least partially surrounds a plunger movable axially relative to the punch. During the first compaction step one or both punches may move. During the second compaction step one or both plungers may move. Conveniently, the particulate compositions of the outer zone would be delivered into the mould cavity above one punch while the plunger associated with that punch project upwardly from it so as to be surrounded by the particulate compositions. If more than one particulate composition is introduced into the outer zone, it is preferred that they are introduced sequentially, so as to produce layers of varying composition. Compaction of the particulate compositions in the outer zone would then be carried out by urging the two punches relatively towards each other, although one may remain stationary relative to the mould cavity if desired. Compaction of the particulate composition in the inner zone would be carried out by urging the two plungers relatively towards each other, although again one may be driven towards the other which remains immobile.
Such a process is preferably carried out using a rotary tableting press in which a rotary table defines a plurality of mould cavities and in which a pair of punches each with a respective axially movable plunger is associated with each mould cavity.
An advantage of the process of this invention is that the core region and surrounding region of the tablet can both be compacted from powder compositions
Appel Peter William
Boskamp Jelles Vincent
Gupta Anshu Mali
Joueux Christophe Michel
van der Kraan Marcel
Boyer Charles
Kopec Mark
Mitelman Rimma
Unilever Home & Personal Care division of Conopco, Inc.
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