EP1866405A1

EP1866405A1 - Dispensing device

Info

Publication number: EP1866405A1
Application number: EP06723561A
Authority: EP
Inventors: Roy van Unilever R & D Vlaardingen HEESEN
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2005-04-05
Filing date: 2006-03-16
Publication date: 2007-12-19
Also published as: WO2006105863A1; GB0506850D0

Abstract

One or more laundry treatment tablets in combination with a dispensing device; said one or more laundry treatment tablets packaged individually or in groups corresponding with a unit dose, to treat laundry fabric in a washing machine, i) the one or more laundry treatment tablets having a plurality of discrete phases with differing compositions, wherein at least one first phase of the tablet(s) is a smooth phase having an outer surface and at least one second phase of the tablet(s) is a solid phase; and ii) the dispensing device comprising a receptacle, the receptacle comprising a plurality of dispensing apertures and an opening for reception of one or more laundry treatment tablets, characterised in that said dispensing apertures have an average size of from 1 to 20 mm and the receptacle comprises an inner surface and an outer surface spaced apart wherein in use during a laundry treatment cycle, a gap is formed which separates the outer surface of the smooth phase of the tablet(s) from the laundry fabric.

Description

DISPENSING DEVICE

The invention relates to multi-phase laundry treatment tablets containing a smooth (or gel) phase. The invention also relates to a process for treating, for example washing, laundry in a washing machine by employing at least one multi-phase laundry treatment tablet.

Detergent compositions in tablet form have advantages over powdered products in that they do not require measuring and are thus easier to handle and dispense in the washload.

Tablets of a treatment composition are generally made by compressing or compacting a quantity of the composition in particulate form.

Tablets comprising two or more separate regions have also been described. For example WO 01/42416 describes the production of multi-phase moulded bodies comprising a combination of core moulded bodies and a particulate premix. WO 00/61717 describes a detergent tablet which is characterised in that at least part of its outer surface is semi-solid. WO 00/04129 describes a multi-phase detergent tablet comprising a first phase in the form of a shaped body having at least one mould therein and a second phase in the form of a particulate solid compressed within said mould. WO 99/24549 describes a detergent tablet comprising a compressed solid body and a non-compressed gelatinous portion mounted in a mould of said body. WO99/27069 relates to a tablet comprising a compressed and a non-compressed phase, wherein the non-compressed phase improves stability of perfume components.

There also have been prior publications on form stable, solid, and/or transparent smooth or gel-like detergent compositions. In GB 1578289 such a composition comprising soap, detergent and solvent has been proposed, for detergent sticks for use in wash or dry-cleaning pre-treatment . Recently it has been suggested, for example in EP 1,371,729, EP 1,405,900, EP 1,382,368, EP 1,375,636, EP 1,405,901, EP 1,405,902, EP 1,418,224 and WO 03/104380 to prepare tablets comprising a smooth or semi-solid phase.

It is an object of the present invention to provide one or more laundry treatment tablets which exhibit improved dissolution behaviour when used in a laundry washing machine.

According to a first aspect of the invention, there is provided one or more laundry treatment tablets in combination with a dispensing device; said one or more laundry treatment tablets packaged individually or in groups corresponding with a unit dose, to treat laundry fabric in a washing machine, i) the one or more laundry treatment tablets having a plurality of discrete phases with differing compositions, wherein at least one first phase of the tablet (s) is a smooth phase having an outer surface and at least one second phase of the tablet (s) is a solid phase; and ii) the dispensing device comprising a receptacle, the receptacle comprising a plurality of dispensing apertures and an opening for reception of one or more laundry treatment tablets, characterised in that said dispensing apertures have an average size of from 1 to 20mm and the receptacle comprises an inner surface and an outer surface spaced apart wherein in use during a laundry treatment cycle, a gap is formed which separates the outer surface of the smooth phase of the tablet (s) from the laundry fabric.

In a second aspect, the invention provides a process for treating laundry fabric in a washing machine by employing the combination of the first aspect of the invention, the process comprising the step of removing the said one or more tablets from the packaging and inserting the one or more laundry treatment tablets into the receptacle, inserting the receptacle into the washing machine together with the laundry fabric to be treated and then performing a laundry treatment operation.

According to a third aspect of the invention, there is provided the combination according to the first aspect of the invention in combination with instructions for use according to the method of the second aspect of the invention.

The combination of a dispensing device and a laundry treatment tablet comprising a smooth phase is advantageous because the gap provided between the fabric and the outer surface of the smooth phase of the undissolved tablet (s) prevents, or at least reduces, inhibition of surface erosion by the laundry fabric. Inhibition of surface erosion can lead to reduced dissolution rates of the smooth phases of the tablets. The provision of a gap in combination with the size of the apertures ensure that fabrics cannot directly- contact or adhere to the outer surface of the smooth phase of the tablet via the dispensing apertures and that multiple water pathways are maintained throughout the wash cycle.

The apertures are sized so as to provide optimum water pathways to the smooth phase, but sufficiently small to prevent the fabric entering the apertures sufficiently to contact the smooth phase of the tablet. Thus the invention provides improved dissolution of laundry treatment tablets comprising a smooth phase such as, for example, a melt- casted, semi-solid, non-compressed or gel-like phase which often exhibit slow dissolution via surface erosion.

Preferably the laundry treatment tablet of the invention cleans, softens or freshens the laundry fabrics being treated in the washing machine. Most preferably it is a laundry cleaning tablet capable of cleaning the laundry fabrics .

The regions of the tablet are preferably separate layers within a cleaning tablet. However, a discrete region of a tablet could also have other forms for example one or more core(s) or insert (s). Preferably, a "phase" is a discrete region at the tablet having a particular composition and/or physical nature such as morphology, texture or appearance.

The tablets utilised in the present invention may be any suitable shape, e.g. spherical or polyhedral. However, preferably they are of cylindrical shape wherein the two main surfaces (upper side and bottom side) are substantially flat. In one embodiment, the outer surface of the smooth phase is dome-shaped to facilitate pre-treatment application.

The multi-phase tablets used in the present invention comprise at least one smooth phase and at least one solid phase. It may also comprises at least one intermediate phase if the smooth phase comprises a relatively^' high level of liquid component so as to improve the stability of the tablet during storage.

The Smooth Phase

The first phase of the tablet is a smooth phase. For the purpose of this invention the term smooth phase refers to compositions which are on the one hand solid enough to retain their shape at ambient temperature and on the other hand smooth in appearance. Smooth textures are generally of low or no porosity and have, at normal viewing distance, the appearance of a continuous phase for example as opposed to porous and particulate appearance of a compacted particulate material.

Preferably the smooth phase of the tablet is a semi-solid phase. For the purpose of this invention the term semi-solid refers to compositions which are on the one hand solid enough to retain their shape at ambient temperature but which are neither completely solid. A suitable test to check if a composition can be considered as a semi-solid is, for example, described in EP 1,375,636.

The other phases of the laundry treatment tablet are possibly separate layers within a tablet, preferably substantially flat layers. Preferably the smooth phase covers a substantial part of the upper surface of the other phase, e.g. preferably at least 65%, more preferred at least 75%, most preferred more than 90% or even substantially all of the upper surface of the other phase is covered by the first smooth phase. For the purpose of the invention the term upper surface refers to one of the main sides of the laundry treatment tablet which by placing the tablet on a flat surface could be classified as the upper surface. Especially preferably the other phase of the tablet suitably is a layer of compacted particulate material, preferably having a substantially flat upper surface.

Preferably the first smooth phase is a layer having an average thickness of from 0.5 to 10 mm, more preferred 1 to 6 mm, for example 1.5 to 5 mm. Preferably the total weight the smooth phase is from 1 to 40 grammes, more preferred from 3 to 30 grammes, most preferred from 4 to 10 grammes, preferably the level of non-soap surfactants in the smooth phase is from 0.5 to 10 grams, more preferred from 1 to 7 grams .

In an advantageous embodiment of the invention the smooth or semi-solid first phase comprises from 40-100 wt% of non-soap surfactants (based on the total weight of the smooth phase) , more preferred from 50-95 wt%, most preferred the first phase is predominantly constituted by non-soap surfactants e.g. more than 60 wt% for example 70 to 90 wt%. It has been found that the combination of a separate smooth or semisolid phase and these high surfactant levels provide very good dispersing and cleaning properties to the tablet.

Also advantageously the smooth or semi-solid phase may comprise soap for example at a level of 0.1 to 10 wt% based on the weight of the smooth or semi-solid part. Especially preferably the soap is present in a level of at least 1 wt% of the smooth phase. In a very preferred embodiment of the invention the level of C16 soaps is relatively high, particularly it is preferred that at least 50 wt% of the soap is a C16 soap, even more preferred from 60 to 100 wt% of the soap is a C16 soap.

Also advantageously the first smooth phase of the tablet comprises at least 5 wt% of diluent materials having a dielectric constant of from 5 to 16. Also preferably the molecular weight of the diluents is from 50 to 250, e.g. from 100 to 200. Preferred examples of diluents are for example, Tri-ethyleneglycol di-methyl ether or Di- (Ethylene Glycol) Ethyl ether or mixtures thereof. Preferably the level of the diluents is from 5 to 40 wt%, more preferred 2 to 30, most preferred 10-25 wt% based on the weight of the smooth phase. Also preferably the diluents used in the smooth phase preferably have a flashpoint of at least 75⁰C, most preferred above 80⁰C or even above 90 ⁰C.

The smooth or semi-solid phase preferably comprises no or only low levels of water. Preferably the level of water is less than 20 wt % based on the weight of the semi-solid phase, more preferred less than 15 wt%, most preferred from 5 to 12 wt%. Most preferably the smooth or semi-solid phases are substantially free from water, which means that apart from low levels of moisture (e.g. for neutralisation or as crystal water) no additional added water is present.

In one embodiment the outer surface of the smooth phase may comprise from 5 to 25 rounded ridges so as to improve the dissolution rate of the smooth phase of the tablet and reduce contact between the user and the smooth phase. Preferably the rounded ridges are of such a size to prevent projection of ridge peaks through the apertures of the dispensing device.

The smooth phase may be prepared by heating the ingredients together until they melt to form a substantially homogeneous liquid, followed by cooling to solidification and if necessary, cutting or otherwise forming to the desired shape and size.

The Solid Phase

Preferably laundry treatment tablets in accordance to the invention also comprise a second phase which is a solid phase preferably a region of compacted material. The weight of the solid phase may suitably range from 1 to 60 grams, more preferred from 10 to 50 grams, most suitably from 20 to 40 grams. In a preferred embodiment of the invention the second phase comprises no or only low levels of surfactants. Preferably the level of surfactants in the second phase is less than 10 wt% (based on the total weight of the second phase) , more preferred from 0 to 9 wt%, most preferred from 1 to 8 wt% .

The second phase of the tablet is preferably a solid phase, for example this can be prepared by compression or melting. Preferably the second phase is a compacted particulate composition. The second phase preferably comprises ingredients of the tablet other than surfactants. Examples of these ingredients are builders, bleach system, enzymes etc. Preferably the builders in the tablet are predominantly present in the second phase. Preferably the bleach system is predominantly present in the second phase. Preferably the enzymes are predominantly present in the second phase. For the purpose of this invention the term "predominantly present" refers to a situation wherein at least 90 wt% of an ingredient is present in the second phase, more preferred more than 98 wt%, most preferred substantially 100 wt%.

The Receptacle

The receptacle of the dispensing device may be in the form of a flexible or rigid structure. Preferably the receptacle comprises a flexible, loosely fitting net bag with a plurality of apertures for permitting passage of the wash liquor there through. The net bag is preferably flexible so as to prevent damage to any delicate laundry fabrics and loosely fitting with respect to the laundry treatment tablets, thereby allowing the tablets to move freely within the receptacle, therefore, aiding dispersion of the smooth phase of the tablet.

The net bag may comprises a hexagonal, diamond or square mesh structure. However, a hexagonal structure is preferred.

Preferably the dispensing apertures of the net have an average size of from 1 to 20mm, more preferably from 3 to 10mm and most preferably from 3 to 8mm. In one embodiment of the invention, it is approximately 5mm. This average aperture size fulfils the objective of the invention in respect to being sized so as to provide optimum water pathways whilst being sufficiently small to prevent the laundry fabric entering the apertures adequately to contact the smooth phase of the tablet.

Preferably the gap provided by the spacing apart of the inner surface and outer surface of the receptacle may have an average depth of from 0.5 to 2mm, more preferably from 0.75 to 1.5mm. In one embodiment the average depth of the gap is lmm. This sufficiently separates the outer surface of the smooth phase of the tablet from the laundry fabric, without requiring an excessive amount of material thereby reducing environmental impact of the device.

Preferably the receptacle opening has a diameter which is at least double the maximum diameter of the laundry treatment tablet (s). For example if the laundry treatment tablet (s) is in the form of a cylindrical disc shape with a diameter of 4-5cm, the diameter of the receptacle opening is preferably 8-lOcm.

In a preferred embodiment of the invention, the receptacle of the dispensing device further comprises a closure device comprising a drawstring, wherein there is a closure member attached to the drawstring so as to close and lock the receptacle opening in an open or closed orientation.

The closure device may comprise a clamp means or a compressible foam material attached to the drawstring. Preferably it comprises a compressible foam material having a through-hole or channel through which the string passes. The resilience of the material and the size of the hole and/or channel may serve to keep the device in place on the string in the open or closed position. In one embodiment the closure device comprises ethyl vinyl acetate (EVA) foam of the closed cell type.

EVA foam is advantageous because it is highly heat resistant and so retains its compressibility and resistance even during/after high temperature wash cycles. Furthermore, EVA foam provides the combination of the functions of flotation, closure and volume adding into a single member. Therefore, the dispensing device can float in the wash liquor, enhancing the travel of the tablets through the laundry and compression of the flotation device eliminates or at least reduces damage to delicate laundry fabrics.

Typically, the receptacle is reusable and is produced from a material capable of withstanding temperatures for the machine washing or drying of laundry, especially up to 150⁰C. With regard to the net material one example is sold under the trade name NETLON. However other materials capable of withstanding the above temperatures are envisaged.

In one embodiment of the invention the net bag may comprises an upper region and a base region. The upper region and/or base region may comprise a mesh structure which may be joined together or formed integrally. The average size of the apertures in the upper region are preferably the size described with respect to the dispensing device without a separate base region. The size of the apertures in the base region are preferably less than lmm, more preferably less than or equal to 0.9mm and most preferred they are less than or equal to O.βmm. In a preferred embodiment the size of the base apertures are approximately 0.1mm so as to reduces or at least minimise leakage of fluid if the smooth phase of the tablet is prematurely ruptured.

The base material may comprise a closely woven material having a mesh structure, wherein the mesh apertures provide the base apertures. The material of the base may be any suitable material. Preferably, it is polyester.

The base region may comprise a base wall which may be provided by e.g. a gusset region. Alternatively and preferably, the base wall comprises lower regions of the side walls of the receptacle which may be joined together and any apertures in these regions are restricted to the average size as described for the base apertures by enclosing the regions with a cover. In this arrangement the base is more apparent when the laundry treatment tablets have been inserted so as to force lower regions of the side walls to form an effective base.

Preferably, the upper region having dispensing apertures occupies a major part of the total surface area of the receptacle, this major part preferably being in the range of 60% to 95% and more preferably 70% to 95% and even more preferably 80% to 95%. This is advantageous because it ensures the maximum area having the optimum dispensing function due to the presence of dispensing apertures whilst at the same time allowing for the base to prevent leakage during filling.

In this embodiment the mesh structure, the gap provided by the spacing of the inner and outer surface of the receptacle, the diameter of the receptacle opening, the closure device and the material of the upper region of the receptacle may be the same as described with respect to the dispensing device not comprising a base region.

Materials which may be used in tablets of this invention will now be discussed in more detail.

Surfactant Compounds

Compositions which are used in tablets of the invention will contain one or more detergent surfactants. In a laundry treatment composition, these preferably provide from 5 to 50% by weight of the overall tablet composition, more preferably from 8 or 9% by weight of the overall composition up to 40% or 50% by weight. Surfactant may be anionic (soap or non-soap) , cationic, zwitterionic, amphoteric, nonionic or a combination of these.

Anionic surfactant may be present in an amount from 0.5 to 50% by weight, preferably from 2% or 4% up to 30% or 40% by weight of the tablet composition.

Synthetic (i.e. non-soap) anionic surfactants are well known to those skilled in the art. Examples include alkylbenzene sulphonates, particularly sodium linear alkylbenzene sulphonates having an alkyl chain length of Ce-Cis; olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates.

Primary alkyl sulphate having the formula

ROSO₃ ^" M⁺

in which R is an alkyl or alkenyl chain of 8 to 18 carbon atoms especially 10 to 14 carbon atoms and M⁺ is a solubilising cation, is commercially significant as an anionic surfactant. Linear alkyl benzene sulphonate of the formula

where R is linear alkyl of 8 to 15 carbon atoms and M⁺ is a solubilising cation, especially sodium, is also a commercially significant anionic surfactant.

Frequently, such linear alkyl benzene sulphonate or primary alkyl sulphate of the formula above, or a mixture thereof will be the desired anionic surfactant and may provide 75 to 100 wt% of any anionic non-soap surfactant in the composition.

In some forms of this invention the amount of non-soap anionic surfactant lies in a range from 5 to 20 wt% of the tablet composition.

Soaps for use in accordance to the invention are preferably sodium soaps derived from naturally occurring fatty acids, for example, the fatty acids from beef tallow.

Suitable nonionic surfactant compounds which may be used include in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide.

Specific nonionic surfactant compounds are alkyl (C8-22) phenol-ethylene oxide condensates, the condensation products of linear or branched aliphatic C₈-₂o primary or secondary alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylene-diamine. Especially preferred are the primary and secondary alcohol ethoxylates, especially the CVn and Ci₂-_Is primary and secondary alcohols ethoxylated with an average of from 5 to 20 moles of ethylene oxide per mole of alcohol. In some laundry treatment tablets of this invention, the amount of nonionic surfactant lies in a range from 4 to 40%, better 4 or 5 to 30% by weight of the whole tablet.

Many nonionic surfactants are liquids. These may be absorbed onto particles of the composition.

Detergency Builder

A composition which is used in tablets of the invention will usually contain from 5 to 80%, more usually 15 to 60% by weight of detergency builder. This may be provided wholly by water soluble materials, or may be provided in large part or even entirely by water-insoluble material with water- softening properties. Water-insoluble detergency builder may be present as 5 to 80 wt%, better 5 to 60 wt% of the composition.

Alkali metal aluminosilicates are strongly favoured as environmentally acceptable water-insoluble builders for fabric washing. Alkali metal (preferably sodium) aluminosilicates may be either crystalline or amorphous or mixtures thereof, having the general formula:

0 . 8 - 1 . 5 Na₂O - Al₂O₃. 0 . 8 - 6 SiO₂. xH₂0 These materials contain some bound water (indicated as AxH20≤) and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g. The preferred sodium aluminosilicates contain 1.5-3.5 SiO₂ units (in the formula above) . Both the amorphous and the crystalline materials can be prepared readily by reaction between sodium silicate and sodium aluminate, as amply described in the literature.

Suitable crystalline sodium aluminosilicate ion-exchange detergency builders are described, for example, in GB 1429143 (Procter & Gamble) . The preferred sodium aluminosilicates of this type are the well known commercially available zeolites A and X, the novel zeolite P described and claimed in EP 384070 (Unilever) and mixtures thereof.

Conceivably a water-insoluble detergency builder could be a layered sodium silicate as described in US 4664839. NaSKS-6 is the trademark for a crystalline layered silicate marketed by Hoechst (commonly abbreviated as ASKS-6") . NaSKS-6 has the delta-Na₂Si0₅ morphology form of layered silicate. It can be prepared by methods such as described in DE-A-3,417,649 and DE-A-3, 742, 043. Other such layered silicates, such as those having the general formula NaMSi_xO_2x+I. yH₂O wherein M is sodium or hydrogen, x is a number from 1.9 to 4, preferably 2, and y is a number from 0 to 20, preferably 0 can be used.

Water-soluble phosphorous-containing inorganic detergency builders, include the alkali-metal orthophosphates, metaphosphates, pyrophosphates and polyphosphates. Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, orthophosphates and hexametaphosphates .

Non-phosphorous water-soluble builders may be organic or inorganic. Inorganic builders that may be present include alkali metal (generally sodium) carbonate; while organic builders include polycarboxylate polymers, such as polyacrylates, acrylic/maleic copolymers, and acrylic phosphonates, monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono- di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates and hydroxyethyliminodiacetates .

At least one phase (preferably the second phase) of a laundry treatment tablet preferably include polycarboxylate polymers, more especially polyacrylates and acrylic/maleic copolymers which can function as builders and also inhibit unwanted deposition onto laundry fabric from the wash liquor .

Bleach System

Tablets according to the invention may contain a bleach system in at least one phase of a tablet, preferably in the second phase. This preferably comprises one or more peroxy bleach compounds, for example, inorganic persalts or organic peroxyacids, which may be employed in conjunction with activators to improve bleaching action at low wash temperatures. If any peroxygen compound is present, the amount is likely to lie in a range from 10 to 25% by weight of the composition.

Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate, advantageously employed together with an activator. Bleach activators, also referred to as bleach precursors, have been widely disclosed in the art. Preferred examples include peracetic acid precursors, for example, tetraacetylethylene diamine (TAED) , now in widespread commercial use in conjunction with sodium perborate; and perbenzoic acid precursors. The quaternary ammonium and phosphonium bleach activators disclosed in US 4751015 and US 4818426 (Lever Brothers Company) are also of interest. Another type of bleach activator which may be used, but which is not a bleach precursor, is a transition metal catalyst as disclosed in EP-A-458397, EP-A-458398 and EP-A-549272. A bleach system may also include a bleach stabiliser (heavy metal sequestrant) such as ethylenediamine tetramethylene phosphonate and diethylenetriamine pentamethylene phosphonate.

As indicated above, if a bleach is present and is a water- soluble inorganic peroxygen bleach, the amount may well be from 10% to 25% by weight of the composition.

Other Detergent Ingredients

The laundry treatment tablets of the invention may also contain (preferably in the second phase) one of the detergency enzymes well known in the art for their ability to degrade and aid in the removal of various soils and stains. Suitable enzymes include the various proteases, cellulases, lipases, amylases, and mixtures thereof, which are designed to remove a variety of soils and stains from fabrics. Examples of suitable proteases are Maxatase (Trade Mark), as supplied by Gist-Brocades N.V., Delft, Holland, and Alcalase (Trade Mark) , and Savinase (Trade Mark) , as supplied by Novo Industri A/S, Copenhagen, Denmark. Detergency enzymes are commonly employed in the form of granules or marumes, optionally with a protective coating, in amount of from about 0.1% to about 3.0% by weight of the composition; and these granules or marumes present no problems with respect to compaction to form a tablet.

The laundry treatment tablets of the invention may also contain (preferably in the second phase) a fluorescer (optical brightener) , for example, Tinopal (Trade Mark) DMS or Tinopal CBS available from Ciba-Geigy AG, Basel, Switzerland. Tinopal DMS is disodium 4, 4 'bis- (2-morpholino- 4-anilino-s-triazin-β-ylamino) stilbene disulphonate; and Tinopal CBS is disodium 2, 2 ' -bis- (phenyl-styryl) disulphonate .

An antifoam material is advantageously included (preferably in the second phase) , especially if a laundry treatment tablet is primarily intended for use in front-loading drum- type automatic washing machines. Suitable antifoam materials are usually in granular form, such as those described in EP 266863A (Unilever) . Such antifoam granules typically comprise a mixture of silicone oil, petroleum jelly, hydrophobic silica and alkyl phosphate as antifoam active material, absorbed onto a porous absorbed water- soluble carbonate-based inorganic carrier material. Antifoam granules may be present in an amount up to 5% by weight of the composition.

It may also be desirable that a laundry treatment tablet of the invention includes an amount of an alkali metal silicate, particularly sodium ortho-, meta- or disilicate. The presence of such alkali metal silicates at levels, for example, of 0.1 to 10 wt%, may be advantageous in providing protection against the corrosion of metal parts in washing machines, besides providing some measure of building and giving processing benefits in manufacture of the particulate material which is compacted into tablets.

A tablet for fabric washing will generally not contain more than 15 wt% silicate. Preferably the silicate is present in the second phase of the tablet.

Further ingredients which can optionally be employed in a phase of a laundry treatment tablet of the invention (preferably the second phase) include anti-redeposition agents such as sodium carboxymethylcellulose, straight-chain polyvinyl pyrrolidone and the cellulose ethers such as methyl cellulose and ethyl hydroxyethyl cellulose, fabric- softening agents; heavy metal sequestrants such as EDTA; perfumes; and colorants or coloured speckles.

Further ingredients which can optionally be used in tablets of the invention, preferably in the second phase are dispersing aids. Examples of suitable dispersing aids are water-swellable polymers (e.g. SCMC) highly soluble materials (e.g. sodium citrate, potassium carbonate or sodium acetate) or sodium tripolyphospate with preferably at least 40% of the anhydrous phase I form.

Particle Size and Distribution

The second phase of laundry treatment tablet of this invention, is a preferably a matrix of compacted particles.

Preferably the particulate composition has an average particle size in the range from 200 to 2000 μm, more preferably from 250 to 1400 μm. Fine particles, smaller than 180 μm or 200 μm may be eliminated by sieving before tableting, if desired, although we have observed that this is not always essential.

While the starting particulate composition may in principle have any bulk density, the present invention is especially relevant to tablets made by compacting powders of relatively high bulk density, because of their greater tendency to exhibit disintegration and dispersion problems. Such tablets have the advantage that, as compared with a tablet derived from a low bulk density powder, a given dose of composition can be presented as a smaller tablet.

Thus the starting particulate composition may suitably have a bulk density of at least 400 g/litre, preferably at least 500 g/litre, and perhaps at least 600 g/litre. Tableting machinery able to carry out the manufacture of tablets of the invention is known, for example suitable tablet presses are available from Fette and from Korch.

Tableting may be carried out at ambient temperature or at a temperature above ambient which may allow adequate strength to be achieved with less applied pressure during compaction. In order to carry out the tableting at a temperature which is above ambient, the particulate composition is preferably supplied to the tableting machinery at an elevated temperature. This will of course supply heat to the tableting machinery, but the machinery may be heated in some other way also.

The size of a tablet will suitably range from 10 to 160 grams, preferably from 15 to 60 g, depending on the conditions of intended use, and whether it represents a dose for an average load in a fabric washing or dishwashing machine or a fractional part of such a dose. The tablets may be of any shape. However, for ease of packaging they are preferably blocks of substantially uniform cross- section, such as cylinders or cuboids. The overall density of a tablet preferably lies in a range from 1040 or 1050gm/litre up to 1600gm/litre.

The above description of the tablet has been given with reference to a tablet constituted by one or two phases. It will however be understood that each of the phase may be composed of a limited number of discrete regions. Laundry treatment tablets of the invention may be manufactured by any suitable method e.g. the pre-preparation of the smooth phase e.g. by extrusion or melt-casting followed by assembly of the smooth phase and the other phases of the tablet. Also the second phase of compressed particulate material may be pre-prepared followed by in-situ preparation of the smooth phase e.g. by casting, coating or spraying, or assembly of said compressed phase with a separately prepared smooth phase. Typical processing conditions for preparing the smooth phase or the compressed phase are for example disclosed in the documents as described above.

The invention will be more clearly understood from the following description of some of the embodiments thereof, given by way of example only, with reference to the accompanying drawings in which: -

Figure 1 is a perspective view of a first embodiment of the dispensing device according to the invention;

Figure 2 is a perspective view of a second embodiment of the dispensing device according to the invention;

Figure 3 is an enlarged schematic view of the mesh of the receptacle of the dispensing device of figure 1 and 2; and

Figure 4 is an enlarged view of the closure device of the dispensing device of figure 1 and 2. In the first embodiment of the invention, figure 1, there is illustrated a dispensing device 1 comprising a receptacle 2 in the form of a flexible, loosely fitting, net bag 2 having a plurality of dispensing apertures 20 and an opening 3 for reception of one or more laundry treatment tablets (tablets not shown) . The net bag has a hexagonal mesh structure as shown more clearly in figure 3 and the dispensing apertures have an average size of approximately 5mm.

The device also includes a closure device indicated generally at 30 which consists solely of a generally cylindrical ethylene vinyl acetate (EVA) foam body. The closure device 35 has a central longitudinal through hole 37 through which string 39 runs. The string 39 is part of a drawstring closure arrangement generally indicated at 31.

Thus, the devices includes only flexible parts and includes no rigid parts. The longitudinal through-hole 37 is dimensioned relative to the diameter of the string so as to fit tightly onto the string 39.

The foam body 35 can be manually drawn along the string 39 and its resilience ensures it remains in position to lock the receptacle opening 3 in an open or closed position.

The foam closure device is buoyant in the wash liquor thereby further improving the travel of the net through the laundry fabric and consequently the dispersal of the laundry treatment tablet composition, in particular the smooth phase of the tablet. In an alternative embodiment of the invention, figure 2, there is illustrated a dispensing device 1 comprising a receptacle 2, having a opening 3 for reception of one or more laundry treatment tablets (tablets not shown) , in the form of a flexible, loosely fitting net bag having a hexagonal mesh structure (shown more clearly in figure 3) . The receptacle 2 comprises an upper region 7 having dispensing apertures 20 having an average size of approximately 5mm. The receptacle 2 also has a base 9 comprising the lower portions of the two side walls, (only one 11 shown) , the base 9 is more apparent when the tablets have been inserted so as to force the lower region 9 of the side wall to form a base.

In this embodiment of the invention the base 9 is covered by a shallow sack comprising tightly woven polyester material which has a mesh size and hence base apertures of less than lmm and is in this example approximately 0.1mm.

The net bag 2 is, when laid flat, approximately 12cm in length and approximately 15cm in width. The covered base part is (when viewed with the bag laid flat) approximately 3cm in height (and approximately 15cm in width) . Thus the total surface area is approximately 360cm² of which 90cm² (25%) is occupied by the base 9 and 270cm² (75%) is occupied by the upper part 7.

The dispensing device of the second embodiment includes a closure device as exactly described for the first embodiment. This embodiment is advantageous as the average size of the apertures of the base region can prevent, or at least minimise, any leakage of fluid from the smooth, semi-solid phase of a prematurely ruptured tablet during filling.

The hexagonal mesh structure, as shown in figure 3, is equivalent for both the first and the second embodiment of the invention. The receptacle comprises a inner surface 40 and an outer surface 42 which are spaced apart so as to form a gap 44. This gap 44 has an average depth of lmm and an average aperture size as described in relation to the first or second embodiment. The combination of the average depth of the gap 44 and the average aperture size ensures that the laundry fabrics cannot directly contact or adhere to the outer surface of the smooth phase of the tablet.

The dimensions (12cm x 15cm) provide a bag of manageable size but which is loose fitting for two tablets (each about 4.5 cm diameter and 1.5 cm height) .

The receptacle opening is located on the larger (15cm) side, providing a large opening for introducing the tablet (s). When the net is opened out the opening has a diameter of approximately 9.5cm, which is just over double the diameter of the tablet.

An exemplary laundry treatment tablet formulation is as follows : A detergent powder was made of the following composition by pregranulating the granule ingredients, followed by post- dosing the rest of the ingredients

Smooth or semi-solid parts were prepared of the following composition:

Notes: * is a C16-C18 soap; ** is a C16 soap. Each formulation A1-C3 was prepared with the following solvents: Tri-ethyleneglycol di-methyl ether having a dielectric constant of 7.6 and a molecular weight of 178 ex Clariant (yielding formulations Al, Bl and Cl) or Di (Ethylene Glycol) mono-ethyl ether having an di-electric constant of 15.5 and a molecular weight of 134 ex Sigma (yielding formulations A2, B2 and C2) . As a comparison each formulation was made with dipropylene glycol having a di- electric constant of about 25 as solvent (yielding formulations A3, B3 and C3) .

The mixtures were heated to 80 °C and cast into moulds and cooled to 20⁰C to form firm, 5 grammes smooth and semi-solid parts of 32mm diameter and 6mm high.

Multi-layer tablets are made by pre-σompressing 25 grammes of the powdered composition in a die of 45 mm diameter at 4 kN/cm²' way followed by adherence of a smooth and semi-solid part on top of the compressed layer followed by a final compression step at 0.8 kN/cm². During the final compression step, the smooth and semi-solid part flows by the compaction forces to form a 3.4 mm smooth semi-solid layer adhered on top of the compressed particulate layer. The height of the powdered part after compression is 11 mm.

DISSOLUTION PROPERTIES

Smooth parts of 5 gram each were prepared having a composition as described in the above example and having a cylidrical shape of 19 mm diameter and 22 mm height. Pieces were immersed in water of 20 ⁰C which is stirred at 200 rpm. T80 was determined by measuring the time at which 80% of the smooth part was dissolved. The following results were obtained:

These results clearly show that the use of solvents having a low di-electric constant (formulations Al, A2, Bl, B2, Cl and C2)lead to a marked decrease in dissolution time compared to using diluents with a higher di-electric constant such as DPG (formulations A3,B3 and C3) .

Furthermore these examples show that the use of increased amounts of Clβ soap lead to a decrease in dissolution time (Ax compared to Bx and Cx) Lowest dissolution times are obtained by using a combination of high C16 level soaps and solvents having a low di-electric constant (formulations Bl, B2, Cl and C2) .

In use, the package containing the laundry treatment tablets corresponding to a unit dose (not shown) is torn open and the tablets dropped into the opening 3, so they fall into the base of the device.

The closure device 35 is then grasped between the users fingers and drawn along the string 39 to close the receptacle opening 3, where it remains in place (by the mechanism described above) , to lock the opening 3 closed. The device 1 and tablets contained therein are then placed in a washing machine together with the laundry fabric to be washed and a washing operation is carried out during which the smooth phase of the laundry treatment tablet (s) within the bag 2 will disperse and dissolve. The compressible flotation foam aids flotation of the net in the wash liquor, increasing dispersal of the laundry treatment tablet composition in the liquor. Any undissolved particulate disintegration products of the solid phase of the tablet of a size less then 5 mm will pass out of the bag 2 and be dissolved outside the bag 2. When the washing operation has been completed, the device 1 is removed from the machine and stored for subsequent use.

The above embodiments of the present invention have been described by way of example only and various alternative features or modifications from what has been specifically described and illustrated can be made within the scope of the invention, as will be readily apparent to persons skilled in the art.

Claims

1. One or more laundry treatment tablets in combination with a dispensing device; said one or more laundry treatment tablets packaged individually or in groups corresponding with a unit dose, to treat laundry fabric in a washing machine, i) the one or more laundry treatment tablets having a plurality of discrete phases with differing compositions, wherein at least one first phase of the tablet (s) is a smooth phase having an outer surface and at least one second phase of the tablet (s) is a solid phase; and ii) the dispensing device comprising a receptacle, the receptacle comprising a plurality of dispensing apertures and an opening for reception of one or more laundry treatment tablets, characterised in that said dispensing apertures have an average size of from 1 to 20mm and the receptacle comprises an inner surface and an outer surface spaced apart wherein, in use during a laundry treatment cycle, a gap is formed which separates the outer surface of the smooth phase of the tablet (s) from the laundry fabric.

2. A combination according to claim 1, wherein the laundry treatment tablet cleans, softens or freshens the laundry fabrics .

3. A combination according to claims 1 or 2, wherein the first phase of the laundry treatment tablet is a smooth or semi-solid layer and the second phase of the laundry treatment tablet is a layer of compacted particulate material.

4. A combination according to any preceding claim, wherein the smooth or semi-solid phase comprises from 40 to 100% wt% of surfactants, preferably at from 50 to 95% wt%, most preferably at from 70 to 90 wt% of surfactants

5. A combination according to any preceding claim, wherein the smooth or semi-solid phase comprises soap at a level of from 0.1 to 10% based on the weight of the smooth or semi-solid phase, wherein from 60 to 100% wt% of soap is a Clβ soap.

6. A combination according to any preceding claim, wherein the smooth or semi-solid phase comprises diluent materials at a level of form 5 to 40% based on the weight of the smooth or semi-solid phase having a di-electric constant of from 5 to 16.

7. A combination according to any preceding claim, wherein the receptacle of the dispensing device comprises a mesh structure.

8. A combination according to any preceding claim, wherein the dispensing apertures of the net bag have an average size of from 3 to 10mm, preferably from 3 to 8mm.

9. A combination according claims 1-7, wherein the receptacle comprises a base region, an upper region and a plurality of dispensing apertures having an average size of from 1 to 20mm situated in the upper region of the receptacle and any base apertures in the base of the device having an average size of less than lmm.

10. A combination according to any preceding claim, wherein the gap provided by the spacing apart of the outer surface and the inner surface of the receptacle has an average depth of from 0.5 to 2mm.

11. A combination according to any preceding claim, wherein the receptacle comprises a closure member which is (a) buoyant so as to further act as a flotation member during a washing operation and (b) resiliently compressible to allow compression when in contact with the laundry during a washing operation and tablets during storage, and expansion to a volume adding configuration during a washing operation.

12. A process for treating laundry in a washing machine by employing a combination according to any preceding claim and comprising the step of removing the said one or more tablets from the packaging and inserting the one or more laundry treatment tablets into the receptacle inserting the receptacle into the washing machine together with the laundry fabric to be treated and then performing a laundry treatment operation.

13. A package for laundry treatment tablets incorporating the combination of any of claims 1-11 including instructions for a method of treating laundry according to claim 12.