Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2000-01-18
2001-10-23
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
Reexamination Certificate
active
06306814
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.
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 normally is made from more than one composition. Tablets which are “heterogenous” in that they are subdivided into two layers have been marketed commercially.
When tablets are formed by compaction of a particulate composition they are generally made by urging two punches towards each other within a surrounding mould—or possibly one punch is driven into a closed mould.
The resulting tablet has a pair of end faces spaced apart from each other and a peripheral surface which may be cylindrical. If the tablet has two layers, each end face will be formed by one layer and the periphery will be provided partly by one layer and partly by the other.
When making a tablet with two layers, an appropriate procedure is to put the composition for one layer into a mould, lightly compact it, then add the composition for the second layer and compact the entire contents of the mould at a greater pressure which further compacts the first layer as well as compacting the second layer and joining the two layers together.
As well as tablets which are subdivided into two layers, other configurations for subdivision of the tablet into more than one region have also been envisaged and are mentioned in GB-A-911204 for instance. Tablets in which a central core region lies at the same level as the surrounding part of one end face of the tablet have been shown in Registered Design applications. The manufacture of such tablets was not disclosed but would presumably use a single punch to shape the end face and would require subjecting the entire tablet to a compaction step with greater pressure than used in any intermediate compaction step.
Broadly, aspects of the present invention reside in the provision of tablets wherein each tablet has a pair of opposite faces spaced apart from each other and joined by a peripheral surface of the tablet, wherein the tablet is subdivided into at least two regions which are each visible at a said face, wherein there are distinctive features and/or properties which can be achieved through separate compaction of the regions.
In a first aspect, the present invention provides a detergent tablet of compacted particulate composition which has a pair of opposite faces spaced apart from each other and joined by a peripheral surface of the tablet, wherein the tablet has a first region which provides a first part of a said face and a second region which provides an adjoining part of the face with a discontinuity such as a step or groove at the junction of the said parts of the face.
Preferably the arrangement is such that the first part of the face is not at the same level as the adjacent part, so that there is a step at the junction of the two 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 another region 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 first region might for instance extend to the tablet periphery and form a portion of the peripheral surface. A region surrounding a core might possibly be split into two layers, and a 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, but is 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.
The regions of the tablet will usually be of different composition or different physical properties or both.
In a second aspect, this invention provides a process for producing a detergent tablet which has a pair of opposite faces spaced apart from each other and joined by a peripheral surface of the tablet, wherein the tablet has at least two discrete regions visible at a said face, comprising steps of:
introducing a 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 composition around the plunger in the cavity, thereby compacting it into one region of the tablet
withdrawing the plunger from within the compacted composition, introducing a second 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 another region of the tablet.
There is no need to apply any substantial compaction pressure to the first composition when compacting the second, thus allowing the compaction pressure applied to each of the two regions of the tablet to be chosen independently. However, some light pressure may be applied to the (already compacted) first composition to hold it steady while the second composition 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 first particulate composition 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 composition.
Compaction of the first particulate composition 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 second particulate composition 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 within a single mould cavity. There is no necessity to prefabricate a core region in one mould cavity and somehow position it within another mould cavity. A further advantage is that the tableting pressures applied to each of the compositions can be chosen independently.
The process may lead to tablets in which the compacted second composition provides a part of at least one tablet face which is inset from an adjacent or surrounding part of the tablet face provided by the first composition.
Recessing the exposed area of a region can be advantageous in itself. At the time of use, tablets may be placed in a washing machine together with fabrics with the result that the fabrics may come into direct contact with the tablet before it disintegrates in the wash water. Recessing the exposed area of a tablet region will reduce the opportunity for direct contact between fabrics and the exposed surface of that region (especially if that region is a central core) making it
Appel Peter William
Boskamp Jelles Vincent
Joyeux Christophe Michel
van der Kraan Marcel
Wagner Henning
Douyon Lorna M.
Mitelman Rimma
Unilever Home & Personal Care USA
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