Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Reexamination Certificate
2001-08-29
2003-10-07
Hardee, John (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
C510S441000, C510S446000
Reexamination Certificate
active
06630438
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to perfumed detergent tablets, especially those adapted for use in washing machines, and to processes for making such tablets.
BACKGROUND OF THE INVENTION
Perfumed products are well-known in the art. However, consumer acceptance of such perfumed products like laundry and cleaning products is determined not only by the performance achieved with these products but also by the aesthetics associated therewith. The perfume components are therefore an important aspect of the successful formulation of such commercial products.
In addition, a clay mineral compound is a desirable ingredient of such laundry and cleaning product, in particular those products which are in tablet form.
Indeed, the clay can provide softening benefit but can also serve as a disintegrant of such detergent tablets.
However, a problem encountered with perfumed detergent tablets containing a clay mineral compound is that the clay can have a detrimental effect on the performance of the perfume contained therein. Hence, not to be bound by theory, it is believed that due to the close physical proximity given by the tablet, the perfume is absorbed into the clay where it can interact with heavy metal ions and acid or base sites within the clay which as result may cause a discoloration of the clay. Still, the interaction between the perfume and the clay may also result in the tablet having a less attractive odour.
Accordingly, it is an object of the invention to provide a perfumed detergent tablet comprising a clay mineral compound which exhibit good perfume performance with reduced discoloration of the clay.
Further, cleaning compositions in tablet form have often been proposed, however these have not (with the exception of soap bars for personal washing) gained any substantial success, despite the several advantages of products in a unit dispensing form. One of the reasons for this may be that detergent tablets require a relatively complex manufacturing process. In particular, it is often desirable to provide the tablet with a coating and this adds to the difficulties of manufacture.
While tablets without a coating are entirely effective in use, they usually lack the necessary surface hardness to withstand the abrasion that is a part of normal manufacture, packaging and handling. The result is that non-coated tablets suffer from abrasion during these processes, resulting in chipped tablets and loss of active material.
Finally, coating of tablets is often desired for aesthetic reasons, to improve the outer appearance of the tablet or to achieve some particular aesthetic effect.
Numerous methods of tablet coating have been proposed, and many of these have been suggested for detergent tablets. However, all of these methods have certain disadvantages, as will be explained below.
GB-A-0 989 683, published on Apr. 22nd, 1965, discloses a process for preparing a particulate detergent from surfactants and inorganic salts; spraying on water-soluble silicate; and pressing the detergent particles into a solid form-retaining tablet. Finally, a readily water-soluble organic film-forming polymer (for example, polyvinyl alcohol) provides a coating to make the detergent tablet resistant to abrasion and accidental breakage.
EP-A-0 002 293, published on Jun. 13th, 1979, discloses a tablet coating comprising hydrated salt such as acetate, metaborate, orthophosphate, tartrate, and sulphate.
EP-A-0 716 144, published on Jun. 12th, 1996, also discloses laundry detergent tablets with water-soluble coatings which may be organic polymers including acrylic/maleic co-polymer, polyethylene glycol, PVPVA, and sugar.
WO9518215, published on Jul. 6th, 1995, provides water-insoluble coatings for solid cast tablets. The tablets are provided with hydrophobic coatings including wax, fatty acid, fatty acid amides, and polyethylene glycol.
EP-A-0 846 754, published on the 10
th
of June 1998, provides a tablet having a coating comprising a dicarboxylic acid, the coating material typically having a melting point of from 40° C. to 200° C.
EP-A-0 846 755, published on the 10
th
of June 1998, provides a tablet having a coating comprising a material insoluble in water at 25° C., such as C12-C22 fatty acids, adipic acid or C8-C13 dicarboxylic acids.
EP-A-0 846 756, published on the 10
th
of June 1998, provides a tablet having a coating comprising a disintegrant material and preferably an effervescent material.
Recently, it has been found means by which coated tablets can be provided with a coating so that they can be stored, shipped and handled without damage, the coating being easily broken when the tablet is in the washing machine, releasing the active ingredients into the wash solution. Typical of such disclosure can be found in pending European patent applications EP 99870017.3, EP 99870018.1, and EP 99870019.9.
However, whilst giving satisfactory results, it has now been found that where a clay mineral compound is present in the coating of the detergent tablet, the clay, for the same believed reasons stated above, can have a detrimental effect on the performance of the perfume contained therein as well as on the appearance of the coating, i.e. discoloration of the coating.
These problems have further been found more acute overtime, and more particularly where the coating also comprises an acid having a melting point of at least 40° C., more particularly with a melting point of at least 145° C.
Accordingly, the detergent formulator is also faced with the problems of providing a coated tablet having a coating which has satisfactory appearance, is sufficiently hard to protect the tablet from mechanical forces when stored, shipped and handled, and disperses readily in an aqueous solution whilst still giving satisfactory perfume performance.
Further, the perfuming of detergent tablet is a concern to the detergent formulator. Hence, the presence of the coating on the tablet can reduce the diffusion of the perfume from the tablet resulting in a less attractive odour.
It has now surprising been found that perfume compositions which contain less than 0.6% by weight of the perfume of Schiff Base in a detergent tablet overcomes these problems. Such a finding is surprising because Schiff bases which are generally known to have a yellow colouration to start with, were not expected to give rise to the discolouration of the clay, especially over time.
SUMMARY OF THE INVENTION
The present invention is a perfumed detergent tablet, the tablet comprising a clay mineral compound; and wherein the perfume comprises less than 0.6% of Schiff-base by weight of the perfume composition.
By “perfumed detergent tablet”, it is meant that the perfume can be present in the coating if present, or in the detergent composition, or both.
DETAILED DESCRIPTION OF THE INVENTION
Clay
An essential ingredient of the detergent tablet is a clay. The clay may be present in any of the detergent composition, the coating if present, or both.
By clay mineral compound (or in abbreviation, “clay”), it is meant herein a hydrous phyllosilicate, typically having a two or three layer crystal structure. For clarity, it is noted that the term clay mineral compound, as used herein, excludes sodium aluminosilicate zeolite builder compounds, which however, may be included in the compositions of the invention as optional components. Further description of clays may be found in Kirk-Othmer, Encyclopaedia of Chemical Technology, 4th edition, Volume 6, page 381, as published by John Wiley and Sons.
The clay mineral compound is preferably a smectite clay compound. Smectite clays are disclosed in the U.S. Pat. Nos. 3,862,058, 3,948,790, 3,954,632 and 4,062,647 and European Patents No.s EP-A-299,575 and EP-A-313,146 all in the name of the Procter and Gamble Company.
The term smectite clays herein includes both the clays in which aluminium oxide is present in a silicate lattice and the clays in which magnesium oxide is present in a silicate lattice. Typical smectite clay compounds include the compounds having the general formula Al
2
(Si
2
O
5
)
2
(OH)
2
Arnau Jose
Cunningham Philip Andrew
Green Michael
McRitchie Allan Campbell
Corstanje Brahm J.
Dressman Marianne
Hardee John
The Procter & Gamble & Company
Zerby Kim W.
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