Bull's-eye tablet

Details Bull's-eye tablet Bull's-eye tablet

1999-11-04

2001-06-26

Douyon, Lorna M. (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

Solid, shaped macroscopic article or structure

C510S191000, C510S224000, C510S294000, C510S298000, C252S175000, C252S176000

Reexamination Certificate

active

06251848

ABSTRACT:

This invention relates to detergent shaped bodies which allow active substances to be separated from one another and which are designed as a special case of a core/jacket shaped body. More particularly, the invention relates to shaped bodies of detergents and washing aids such as, for example, dishwasher tablets, detergent tablets, cleaning tablets, bleach tablets, stain remover tablets, water softening tablets and lavatory cleaning tablets.
Detergent shaped bodies are widely described in the prior-art literature and are enjoying increasing popularity among consumers because they provide for easy dosing, require minimal packaging and are aesthetically attractive. Various designs of such shaped bodies are known from the prior art and from everyday living, ranging from various shapes (angular, round, etc.) and colors to multiphase shaped bodies. Multilayer tablets (“two-phase tabs”), ring/core tablets and core/jacket tablets have established themselves in the prior art, above all for releasing various active substances at different rates or for separating ingredients which are incompatible with one another. Bull's-eye tablets are core/jacket tablets in which the core is not surrounded in all directions by the jacket, but instead is visible at the surface of the tablet.
European patent application 005 100 (Jeyes Group), for example, describes lavatory cleaning tablets in the form of recessed tablets, core/jacket tablets and ring/core tablets. This document describes several possible forms in general terms but does not go into special geometries in the case of bull's-eye tablets. The drawings of this patent application show bull's-eye tablets in which the visible core is flush with the tablet surface (FIGS. 1, 2 and 6) or projects trapezoidally therefrom (FIGS. 10, 11 and 12). The contour line of the underneath of the core is always either parallel to the base of the tablet or is trapezoidal with a part parallel to the base of the tablet.
European patent application 481 547 (Unilever) describes multilayer detergent tablets in the form of ring/core tablets which comprise at least three layers (inner layer, barrier layer and outer layer). This document, which is not concerned with bull's-eye tablets, does not discuss geometric parameters either.
Multiphase or multilayer detergent shaped bodies are described, for example, in European patent applications EP 481 792 (Unilever), EP 481 793 (Unilever) and International patent application WO 97/03177 (Benckiser).
Bull's-eye tablets are not widely described in the prior art because their production involves particular problems. Thus, the outlay on machinery is considerable because a core first has to be formed by compression and then introduced by a transfer and centering mechanism into a bed of premix which, after compression, provides the bull's-eye tablet. Compared with a conventional two-layer tablet, therefore, at least two tablet presses have to be available for a bull's-eye tablet because the core visible at the surface is smaller (and hence requires a smaller die) than the tablet carrying the core. On the other hand, the core has to be precompressed to form a shaped body sufficiently stable to be able to be moved by the transfer and centering mechanism. In this way, the adhesion between the core and the tablet carrying it is reduced to the point where, in the extreme case, the core can become separated from the tablet.
During the compression of particulate premixes to form a bull's-eye tablet, the premix to be compressed is subjected to a greater load where the core is placed than at the margins where the surface of the shaped body carrying the core is visible. It is precisely bull's-eye tablets which are often attended by the problem that the mechanical stability of the tablet is too low. Thus, the region, which surrounds the “bull's-eye”, often disintegrates when the top punch is withdrawn or the premix is compacted to a greater extent under the shaped body so that, subsequently, this part of the tablet does not dissolve as well as the rest which can have an extremely adverse effect in the case of detergent tablets in particular.
On the other hand, bull's-eye tablets have advantages which make them particularly attractive as detergent tablets. Special detergent ingredients can be precompressed in the core so that incompatible constituents are separated. Another factor not to be ignored is the aesthetic aspect because, by virtue of their “fried egg structure”, bull's-eye tablets have a high consumer appeal.


REFERENCES:
patent: 3279995 (1966-10-01), Reid
patent: 3407144 (1968-10-01), Bath
patent: 3557003 (1971-01-01), Morris et al.
patent: 4256599 (1981-03-01), Krisp et al.
patent: 4767559 (1988-08-01), Kruse et al.
patent: 4996061 (1991-02-01), Webb et al.
patent: 5133892 (1992-07-01), Chun et al.
patent: 5759974 (1998-06-01), Menke et al.
patent: 5962387 (1999-10-01), Gorlin et al.
patent: 5972870 (1999-10-01), Anderson
patent: 0 055 100 (1982-06-01), None
patent: 0 481 547 (1992-04-01), None
patent: 0 481 792 (1992-04-01), None
patent: 0 481 793 (1992-04-01), None
patent: WO97/03177 (1997-01-01), None

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