Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2001-03-22
2004-01-13
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Solid, shaped macroscopic article or structure
C510S294000, C510S298000, C510S405000, C510S434000, C510S441000, C510S477000, C510S488000
Reexamination Certificate
active
06677295
ABSTRACT:
The present invention relates to detergent tablets, especially those adapted for use in washing.
Although cleaning compositions in tablet form have often been proposed, 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 usually dissolve slower than the constituent powders from which they are made, simply because the constituent powders are forced close together in the tablet, with comparatively little opportunity for water to permeate between them. This gives rise to the problem that slow dissolving tablets cause residues which may be visible throught the door of the washing machine during the wash cycle, or which stick to the fabrics at the end of the wash cycle, or both.
EP-A-0 716 144, published on Jun. 12, 1996, discloses laundry detergent tablets with water-soluble coatings which may be organic polymers including acrylic/maleic co-polymer, polyethylene glycol, PVPVA, and sugar. It states that the tablets of the invention preferably have a diametral fracture stress of at least 5 kPa. The speed of disintegration of the tablets is measured by means of a test using a metal gauze.
However, in certain front loading washing machines, problems of tablet residues appearing visibly at the window of the washing machine have still been encountered.
The object of the present invention is to provide tablets with a core which is formed by compressing a particulate material, the particulate material comprising surfactant and detergent builder, the tablet being suitable for storing, shipping and handling without breakage.
A further object of the invention is to provide a tablet comprising a soft core which breaks up easily and rapidly, releasing the active ingredients into the wash solution and which completely disintegrates and disperses in alkaline or surfactant-rich solutions such as the wash liquor.
SUMMARY OF THE INVENTION
The object of the invention is achieved by providing a detergent tablet comprising a core and a coating, the core having a diametral fracture stress of less than 15 kPa, and the core comprising a non-gelling binder, wherein the coated detergent tablet has a diametral fracture stress of at least 20 kPa.
In a further aspect of the invention there is provided a detergent tablet having a diametral fracture stress of at least 20 kPa, the tablet giving less than 18 g residue at the end of the washing machine cycle under stressed test, the stressed test consisting of three tablets, each tablet weighing 60 g, being placed in the bottom of the drum of a Miele® W831 washing machine, 2.5 kg of mixed fabric load being placed in the drum on top of the tablets, and the machine being run using a “whites/colours” short cycle of 30° C.
In a further aspect of the invention a method is provided for dispensing a detergent tablet from the dispensing drawer of a front loading washing machine.
DETAILED DESCRIPTION OF THE INVENTION
Detergent tablets of the present invention can be prepared simply by mixing the solid ingredients together and compressing the mixture in a conventional tablet press as used, for example, in the pharmaceutical industry. Preferably the principal ingredients, in particular gelling surfactants, are used in particulate form. Any liquid ingredients, for example the surfactant or suds suppressor, can be incorporated in a conventional manner into the solid particulate ingredients.
In particular for laundry tablets, the ingredients such as builder and surfactant can be spray-dried in a conventional manner and then compacted at a suitable pressure.
The detergent tablets can be made in any size or shape and can, if desired, be surface treated before coating, according to the present invention. In the core of the tablet is included a surfactant and a builder which normally provides a substantial part of the cleaning power of the tablet. The term “builder” is intended to mean all materials which tend to remove calcium ion from solution, either by ion exchange, complexation, sequestration or precipitation.
The particulate material used for making the tablet of this invention can be made by any particulation or granulation process. An example of such a process is spray drying (in a co-current or counter current spray drying tower) which typically gives low bulk densities 600 g/l or lower. Particulate materials of higher density can be prepared by granulation and densification in a high shear batch mixer/granulator or by a continuous granulation and densification process (e.g. using Lodige® CB and/or Lodige® KM mixers). Other suitable processes include fluid bed processes, compaction processes (e.g. roll compaction), extrusion, as well as any particulate material made by any chemical process like flocculation, crystallisation sentering, etc. Individual particles can also be any other particle, granule, sphere or grain.
The particulate materials may be mixed together by any conventional means. Batch is suitable in, for example, a concrete mixer, Nauta mixer, ribbon mixer or any other. Alternatively the mixing process may be carried out continuously by metering each component by weight on to a moving belt, and blending them in one or more drum(s) or mixer(s). The non-gelling binder can be sprayed on to the mix of some, or all of, the particulate materials. Other liquid ingredients may also be sprayed on to the mix of particulate materials either separately or premixed. For example perfume and slurries of optical brighteners may be sprayed. A finely divided flow aid (dusting agent such as zeolites, carbonates, silicas) can be added to the particulate materials after spraying the binder, preferably towards the end of the process, to make the mix less sticky.
The tablets may be manufactured by using any compacting process, such as tabletting, briquetting, or extrusion, preferably tabletting. Suitable equipment includes a standard single stroke or a rotary press (such as Courtoy®, Korch®, Manesty®, or Bonals®). The tablets prepared according to this invention preferably have a diameter of between 40 mm and 60 mm, and a weight between 25 and 100 g. The ratio of height to diameter (or width) of the tablets is preferably greater than 1:3, more preferably greater than 1:2. The compaction pressure used for preparing these tablets need not exceed 5000 kN/m
2
, preferably not exceed 3000 kN/m
2
, and most preferably not exceed 1000 kN/m
2
.
Suitable non-gelling binders include synthetic organic polymers such as polyethylene glycols, polyvinylpyrrolidones, polyacrylates and water-soluble acrylate copolymers. The handbook of Pharmaceutical Excipients second edition, has the following binders classification: Acacia, Alginic Acid, Carbomer, Carboxymethylcellulose sodium, Dextrin, Ethylcellulose, Gelatin, Guar gum, Hydrogenated vegetable oil type I, Hydroxyethyl cellulose, Hydroxypropyl methylcellulose, Liquid glucose, Magnesium aluminum silicate, Maltodextrin, Methylcellulose, polymethacrylates, povidone, sodium alginate, starch and zein. Most preferable binders also have an active cleaning function in the laundry wash such as cationic polymers, i.e. ethoxylated hexamethylene diamine quaternary compounds, bishexamethylene triamines, or others such as pentaamines, ethoxylated polyethylene amines, maleic acrylic polymers.
The non-gelling binder materials are preferably sprayed on and hence have an appropriate melting point temperature below 70° C. and preferably below 50° C. so as not to damage or degrade the other active ingredients in the matrix. Most preferred are non-aqueous liquid binders (i.e. not in aqueous solution) which may be sprayed in molten form. However, they may also be solid binders incorporated into the matrix by dry addition but which have binding properties within the tablet.
The non-gelling binder materials are preferably used in an amount within the range from 0.1 to 15% of the composition, more preferably below 5% and especially if it is a non laundry active material below 2% by weight of the ta
Ongena Steven Rene
Tcheou Eric
Charles Mark A.
Douyon Lorna M.
Dressman Marianne
Matthews Armina E.
The Procter & Gamble & Company
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