Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Solid – shaped macroscopic article or structure
Reexamination Certificate
2000-06-08
2001-08-07
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, C510S344000, C510S462000
Reexamination Certificate
active
06271190
ABSTRACT:
This invention relates to cleaning compositions in the form of tablets. These tablets are intended to disintegrate when placed in water and thus are intended to be consumed in a single use. The tablets may be suitable for use in machine dishwashing, the washing of fabrics or other cleaning tasks.
Detergent compositions in tablet form and intended for fabric washing have been described in a number of documents including, for example, GB-A-911204 (Unilever), WO 90/02165 (Henkel) and EP-A-711827 (Unilever) and are now sold commercially. Tablets containing bleach for use as an additive to a fabric washing liquor have been disclosed in U.S. Pat. No. 4,013,581 (Huber/Procter and Gamble). Tablets containing a water softening agent, for use as an additive in cleaning, are sold commercially and are one form of tablet disclosed in EP-A-838519 (Unilever). Tablets of composition suitable for machine dishwashing are sold commercially. Tablets have several advantages over powdered products: they do not require measuring and are thus easier to handle and dispense into the washload, and they are more compact, hence facilitating more economical storage.
Tablets of a cleaning composition are generally made by compressing or compacting a composition in particulate form. Although it is desirable that tablets have adequate strength when dry, yet disperse and dissolve quickly when brought into contact with water, it can be difficult to obtain both properties together. Tablets formed using a low compaction pressure tend to crumble and disintegrate on handling and packing; while more forcefully compacted tablets may be sufficiently cohesive but then fail to disintegrate or disperse to an adequate extent in the wash. Tableting will often be carried out with enough pressure to achieve a compromise between these desirable but antagonistic properties. However, it remains desirable to improve one or other of these properties without detriment to the other so as to improve the overall compromise.
If a tablet contains organic surfactant, this functions as a binder, plasticising the tablet. However, it can also retard disintegration of the tablet by forming a viscous gel when the tablet comes into contact with water. Thus, the presence of surfactant can make it more difficult to achieve both good strength and speed of disintegration: the problem has proved especially acute with tablets formed by compressing powders containing surfactant and built with insoluble detergency builder such as sodium aluminosilicate (zeolite).
The use of crude cellulosic particles such as sawdust or woodflour was suggested many years ago in U.S. Pat. No. 2,560,097, but in the context of one-use tablets for handwashing where the material serves as a filler and the tablets were disintegrated in use by handling.
It is known to include materials whose function is to enhance disintegration of tablets when placed in wash water. For example, our EP-A-838519 mentioned above teaches the use of sodium acetate trihydrate for this purpose.
A number of documents have taught that the disintegration of tablets of cleaning composition can be accelerated by incorporating in the tablet a quantity of a water-insoluble but water-swellable polymeric material. Such documents include WO 98/40462, 98/40463, 98/55575, 98/55582 and 98/55583.
These documents disclose the use of materials derived from timber. WO 98/40462 mentions the use of a material known in the papermaking industry as “Thermomechanical pulp”. Fibres obtained from timber by mechanical processing combined with dispersion in water generally contain 35% or more of cellulose and 30% or less of lignin.
Cellulose fibres may be chemically treated to remove this lignin as is done when making high quality white paper. In the papermaking industry the resulting purified fibres are referred to a “chemical fibres”.
We have now found that a good speed of tablet disintegration, combined with satisfactory strength, can be achieved through use of cellulosic material which does not come from the wood of trees.
So, according to a first aspect of this invention, there is provided a tablet of compacted particulate cleaning composition containing at least one cleaning ingredient which is an organic surfactant, a water softening agent or a bleach, wherein the tablet or a discrete region of the tablet contains water-insoluble, water-swellable disintegration-promoting particles which are cellulose-containing material from a plant source other than timber.
A number of plant sources other than timber have been recognised as sources of natural fibre useful for making textiles (which may be coarse textiles such as sacking), rope or twine. These include such plants as agave which is a source of sisal, jute, flax and hemp plants which are sources of fibres with the same names, and the ceiba tree whose seed capsules yield kapok. Thus it is envisaged that the disintegration-promoting particles will be particles of a cellulose-containing fibrous material originating from a plant source other than timber. This may be the fruit of a plant or the stem of a plant other than a tree. These materials will generally also include lignin and thus can be termed “lignocellulosic”.
A preferred material to be employed in this invention is particles of coconut husk material, sometimes known as coir.
Consequently, in a second aspect this invention provides a tablet of compacted particulate cleaning composition containing at least one cleaning ingredient which is an organic surfactant, a water softening agent or a bleach, wherein the tablet or a discrete region of the tablet contains disintegration-promoting particles of coconut husk material, which is of course water-insoluble. We have discovered that is it strongly water-swellable.
This invention is particularly applicable when the tablets contain both surfactant and detergency builder, as in tablets for fabric washing.
Forms of this invention, preferred and optional features, and materials which may be used, will now be discussed in greater detail.
Discrete Regions/Whole Tablets
A tablet of the invention may be either homogeneous or heterogeneous. In the present specification, the term “homogeneous” is used to mean a tablet produced by compaction of a single particulate composition, but does not imply that all the particles of that composition will necessarily be of identical composition. The term “heterogeneous” is used to mean a tablet consisting of a plurality of discrete regions, for example layers, inserts or coatings, each of which is a matrix of particles derived by compaction from a particulate composition. In a heterogenous tablet according to the present invention, each discrete region of the tablet will preferably have a mass of at least 3 gm.
In a heterogeneous tablet, at least one of the discrete regions contains the said swellable disintegration-promoting particles.
There are a number of possibilities concerning heterogenous tablets. Water-swellable material may or may not be included in every region of a heterogenous tablet, even though the regions differ from each other in some other feature of their composition. Thus the water-swellable material may be present at different concentrations in different tablet regions; it may be present in one region and absent from another; or it may be present at equal concentration in every region of the tablet.
Coconut Husk Material
Coconuts, from the tree
Cocos nucifera
have a fibrous husk (more correctly “mesocarp”) which surrounds the hard shell.
It is conventional to separate the fibres from this husk and utilise them as a coarse textile or rope material termed “coir”. The residue after removal of the fibres can be used in horticulture as a substitute for peat.
For this invention the husk material which is used may be fibres from ripe or immature coconuts—the latter give paler fibres. Alternatively the material may be a husk residue which is left after the removal of at least some fibres. In either case the material is comminuted as necessary, e.g. milled, to a suitable particle size.
The particles may have a mean size, before c
Boskamp Jelles Vincent
Loomans Paulus Jacobus
Douyon Lorna M.
Mitelman Rimma
Unilever Home & Personal Care USA , division of Conopco, Inc.
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