Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2001-06-12
2004-06-15
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
Reexamination Certificate
active
06750193
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the production of cleaning tablets and, more particularly, to process for the production of multiphase cleaning tablets where advantages in terms of cleaning performance are achieved through the division into several phases. Corresponding cleaning tablets include, for example, laundry detergent tablets, tablets for machine dishwashing or for cleaning hard surfaces, bleach tablets for use in washing and dishwashing machines, water softening tablets and stain removing tablets.
BACKGROUND OF THE INVENTION
Cleaning tablets belonging to the product classes mentioned are widely described in the prior art literature and, being easy to dose, are enjoying increasing popularity among consumers. Tabletted detergents have a number of advantages over powder-form or liquid products. They are easier to dose and handle and, by virtue of their compact structure, have advantages in regard to storage and transportation. Accordingly, there is an extremely broad prior art on cleaning tablets which is also reflected in extensive patent literature. At a very early stage, developers of tablet-form products came up with the idea of releasing certain ingredients into the wash cycle under defined conditions through differently composed parts or regions of the tablets in order in this way to improve the outcome of the cleaning process. Besides the core/jacket tablets and ring/core tablets known for some time in the pharmaceutical industry, multilayer tablets in particular have been successfully used and are now available for many aspects of washing and cleaning or hygiene.
Multiphase lavatory cleaning tablets are described, for example, in European patent application EP 0 055 100 (Jeyes Group). This document discloses toilet cleaning blocks which comprise a tablet of a slowly dissolving cleaning composition in which a bleaching tablet is embedded. The document in question also discloses various embodiments of multiphase tablets. According to the teaching of EP 0 055 100, the tablets are produced either by introducing a bleaching tablet into a mold and coating the tablet with the cleaning composition or by casting part of the cleaning composition into the mold, introducing the bleaching tablet and, optionally, overcoating with more cleaning composition. The filling of preformed cavities is neither described nor suggested in this document.
EP 481 547 (Unilever) describes multiphase cleaning tablets which are intended for use in dishwashing machines. These tablets are core/jacket tablets and are produced by compressing the ingredients in stages. First, a bleaching composition is compressed to a form a tablet which is introduced into a die half-filled with a polymer composition which is then filled with more polymer composition and compressed to form a bleaching tablet with a polymer jacket. The procedure is then repeated with an alkaline detergent composition so that a three-phase tablet is obtained. The document in question does not mention the possibility of introducing substances into tablets in the form of a melt.
The controlled release aspect of ingredients has been, and is still being, intensively investigated inter alia in the field of detergents, so that several publications are also available on the subject. So far as cleaning tablets are concerned, most publications suggest the accelerated release of certain regions of the tablet by disintegration aids or effervescent systems whereas the slower release of individual ingredients, for example by coating or by the selective delay of dissolution, tends to assume a lesser role.
The problem addressed by the present invention was to provide a process for producing multiphase cleaning tablets by which it would be possible to produce tablets that would enable certain ingredients to be released under control at predetermined times in the wash cycle. In particular, it would be possible by the process according to the invention to produce cleaning tablets which would be distinguished by excellent storage and transport stability and which would be superior to conventional tablets in their performance in various fields of application. Accordingly, the process to be provided by the invention would also be expected to allow the cleaning tablets to be produced with maximum freedom of formulation for these various applications.
BRIEF DESCRIPTION OF THE INVENTION
It has now been found that cleaning tablets with the requisite properties can be made in a simple and flexible manner by producing tablets comprising a cavity which is subsequently filled with a melt dispersion or emulsion of certain active substances.
Accordingly, the present invention relates to a process for the production of multiphase cleaning tablets comprising the steps of
a) tabletting a particulate premix to form tablets comprising a cavity,
b) preparing a melt suspension or emulsion from a coating material with a melting point above 30° C. and one or more active substance(s) dispersed or suspended therein,
c) filling the cavity tablets with the melt suspension or emulsion at temperatures above the melting point of the coating material and
d) cooling and optionally aftertreating the filled cleaning tablets.
DETAILED DESCRIPTION OF THE INVENTION
Process Step a)
The particulate premix to be tabletted may contain the ingredients typically present in detergents in varying quantities according to the application envisaged for the cleaning tablets produced by the process according to the invention. More particularly, the premix may contain substances from the group of surfactants, builders and complexing agents, bleaching agents, bleach activators, enzymes, polymers and dyes and perfumes. However, certain substances from the groups mentioned may be intentionally omitted from the premix and incorporated as active substance in the melt suspension or emulsion of process step b). Depending on the coating material and active substance selected, it is thus possible to produce tablets which release certain active substances from the tablet either early in the wash cycle or with delay.
Preferred ingredients of the particulate premix are substances from the group of builders. Besides the detersive substances, builders are the most important ingredients of detergents. The cleaning tablets produced in accordance with the invention may contain any of the builders typically used in detergents, i.e. zeolites, silicates, carbonates, organic cobuilders and—providing there are no ecological objections to their use—the phosphates. The builders mentioned may also be used in surfactant-free tablets so that tablets suitable for softening water can be produced in accordance with the invention.
Suitable crystalline layered sodium silicates correspond to the general formula NaMSi
x
O
2x+1
·yH
2
O, where M is sodium or hydrogen, x is a number of 1.9 to 4 and y is a number of 0 to 20, preferred values for x being 2, 3 or 4. Crystalline layered silicates such as these are described, for example, in European patent application EP-A-0 164 514. Preferred crystalline layered silicates corresponding to the above formula are those in which M is sodium and x assumes the value 2 or 3. Both &bgr;- and &Dgr;-sodium disilicates Na
2
Si
2
O
5
·yH
2
O are particularly preferred, &bgr;-sodium disilicate being obtainable, for example, by the process described in International patent application WO-A-91/08171.
Other useful builders are amorphous sodium silicates with a modulus (Na
2
O:SiO
2
ratio) of 1:2 to 1:3.3, preferably 1:2 to 1:2.8 and more preferably 1:2 to 1:2.6 which dissolve with delay and exhibit multiple wash cycle properties. The delay in dissolution in relation to conventional amorphous sodium silicates can have been obtained in various ways, for example by surface treatment, compounding, compacting or by overdrying. In the context of the invention, the term “amorphous” is also understood to encompass “X-ray amorphous”. In other words, the silicates do not produce any of the sharp X-ray reflexes typical of crystalline substances in X-ray diffraction experiments, but a
Beaujean Hans-Josef
Haerer Juergen
Holderbaum Thomas
Nitsch Christian
Richter Bernd
Douyon Lorna M.
Harper Stephen D.
Henkel Kommanditgesellschaft auf Aktien
Murphy Glenn E. J.
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