Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1999-02-04
2001-11-06
Douyon, Lorna M. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S320000, C510S327000, C510S330000, C510S332000, C510S334000, C510S400000, C510S446000, C510S499000, C510S504000, C510S507000
Reexamination Certificate
active
06313080
ABSTRACT:
This invention relates to cleaning compositions in the form of tablets for use in fabric washing.
Detergent powders which are formulated to provide for simultaneously cleaning and softening fabrics are known in the art.
Detergent compositions in tablet form are described, for example, in GB 911204 (Unilever), U.S. Pat. No. 3,953,350 (Kao), JP 60-015500A (Lion), and EP-A-711827 (Unilever). 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 quantity of the composition in particulate form.
According to a first aspect of the present invention, a tablet of compacted particulate cleaning composition for use in fabric washing contains a fabric conditioning agent which is present at a greater concentration in one zone of the tablet than in another zone. The fabric conditioning agent may function to soften or lubricate the fabric and thereby inhibit wrinkling, or may otherwise affect the feel of the fabric after washing.
In certain forms of this invention, the fabric conditioning agent will serve to soften the fabric, and the tablet will be such that the zone containing the fabric softening agent at greater concentration will disintegrate and dissolve (in so far as it is water soluble) later than the said other zone. Consequently, the fabric softening agent will be released into the wash liquor later than some other ingredients of the composition.
As a consequence, the release of at least some of the fabric softening agent into the wash liquor and the deposition of it onto the fabrics in the wash will be delayed until after the washing of fabrics has started and progressed to some extent. This can reduce any interference between the functions of dirt removal from fabric and deposition of softening agent onto the fabric.
Other fabric conditioning agents—such as fabric lubricants—may be such that it is desirable to deliver them at an early stage in the wash. For these, the tablet may be such that the zone containing the fabric conditioning agent at greater concentrations will disintegrate and dissolve (insofar as it is water soluble) later than the said other zone.
Delayed disintegration of one zone of a tablet relative to the other can be implemented in several ways. These may rely on blocking access of water to the zone which is intended to disintegrate later, or may rely on forming the zone from a composition which disintegrates more slowly, or some combination of the two.
One possibility is that a first zone of the tablet is adjacent to the tablet exterior, while a second zone is wholly enclosed within the tablet or is an interior layer of the tablet which is sandwiched between outer layers and provides only a minority proportion of the exterior of the tablet.
A fabric softening agent could then be concentrated in the second zone (and hence concentrated away from the first zone).
Another possibility is that a tablet has a second zone which is a discrete region of the tablet and which disintegrates more slowly than the first zone when the tablet is placed in wash water. Such a second zone which disintegrates more slowly may provide half or somewhat more than half of the tablet exterior, but need not do so.
Such delayed disintegration of the second zone relative to the release of the surfactants contained within the first zone of the tablet may be achieved even when the second zone of the tablet provides a substantial proportion of the exterior of the tablet, by using compositions which have different rates of disintegration in water. For example disintegration enhancing materials may be included within the first zone of the tablet but not the second. Such an arrangement could simply be provided as a two layer tablet, so that each layer provides approximately half the tablet exterior, with the fabric conditioning agent concentrated in one layer.
Thus, different zones of a tablet will probably be a plurality of discrete regions, for example layers, inserts or coatings, each derived by compaction from a particulate composition, such that at least one discrete region disintegrates later than at least one other discrete region of the tablet when the tablet is placed in water, and the said fabric softening agent is present at a greater concentration in the region which disintegrates later than in the region which disintegrates earlier.
In such a “heterogeneous” tablet consisting of a plurality of discrete regions, each discrete region of the tablet will preferably have a mass of at least 1 gram preferably at least 5 gram.
The present invention also provides a process for the production of heterogenous tablets according to the first aspect of the invention. In this second aspect the invention provides a process for making a tablet of compacted particulate detergent composition for use in fabric washing which contains a fabric conditioning agent which is present at a greater concentration in one zone of the tablet than in another zone thereof, which process comprises incorporating the fabric conditioning agent into one of a plurality of detergent compositions at a greater concentration than in a second of said detergent compositions, and thereafter compacting said compositions to make respective discrete regions of the tablet. Suitably, after one composition has been compacted to form a layer of the tablet, a different detergent composition is then compacted against at least one surface of this discrete layer, to form one or more further layers of the tablet adjacent to the tablet exterior. However, other procedures are possible. For instance, GB-A-2324495 teaches the production of two layer tablets without compaction of the first layer. Various documents have contemplated the possibility of discrete regions which are not in the form of layers of a tablet.
If a fabric softening agent is to be concentrated in an interior layer of the tablet, then another detergent composition may be compacted against at least two opposite sides of the layer containing the fabric softening agent.
The tablets of the present invention may contain one or more fabric conditioning agents. The total amount of fabric conditioning agents in the tablets of the invention will, in general, be from 0.1 to 50% by weight, preferably from 0.2 or 0.5 to 10% by weight of the tablet.
A discussion of materials which are known as fabric softening agents and which may be used in the tablets of the present invention is found in published International Patent Application WO 94/24999.
Many suitable and commercially important fabric softening agents are organic compounds containing quaternary nitrogen and at least one carbon chain of 6 to 30 carbon atoms, eg. in an alkyl, alkenyl or aryl substituted alkyl or alkenyl group with at least six aliphatic carbon atoms.
Other suitable fabric softening agents are the analogous tertiary amines and imidazolines, other aliphatic alcohols, esters, amines or carboxylic acids incorporating a C8 to C30 alkyl, alkenyl or acyl group, including esters of sorbitan and esters of polyhydric alcohols, and mineral oils. Certain clays are important as fabric softening agents. Another class of materials used as fabric softening agents are hydrophobically modified cellulose ethers.
Some specific instances of fabric softening agents which may be used in the tablets of the present invention are:
1) Acyclic Quaternary Ammonium Compounds of the Formula (I)
wherein each Q
1
is a hydrocarbyl group containing from 15 to 22 carbon atoms, Q
2
is a saturated alkyl or hydroxy alkyl group containing from 1 to 4 carbon atoms, Q
3
may be as defined for Q
1
or Q
2
or may be phenyl and X
−
is an anion preferably selected from halide, methyl sulphate and ethyl sulphate radicals.
Throughout this discussion of fabric softening agents, the expression hydrocarbyl group refers to alkyl or alkenyl groups optionally substituted or interrupted by functional groups such as —O
Boskamp Jelles Vincent
van der Goot Atze Jan
Westerhout Ronaldus Wilhelmus
Douyon Lorna M.
Mitelman Rimma
Unilever Home & Personal Care USA , division of Conopco, Inc.
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