EP1866404B1

EP1866404B1 - Multi-phase laundry treatment tablets

Info

Publication number: EP1866404B1
Application number: EP06723531.7A
Authority: EP
Inventors: B. J. Ten Brummelhuis; P. E. M. Overdevest; Peter Iwan Stuut
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2005-04-08
Filing date: 2006-03-14
Publication date: 2013-11-27
Anticipated expiration: 2026-03-14
Also published as: WO2006108490A1; ES2448841T3; EP1866404A1

Description

The invention relates to multi-phase laundry treatment tablets containing both a smooth (or gel) phase and a solid phase, and packaging therefor.
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.
CA 2,296,271 discloses a package for detergent tablets.
It is an object of the present invention to provide an improved laundry treatment tablet/s.
According to a first aspect of the invention, there is provided one or more laundry treatment tablets in combination with a package wherein the one or more laundry treatment tablets are packaged individually or in groups corresponding with a unit dose,

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 comprising compacted particulate material and having a diametrical fracture stress of 10-40kPa wherein diametrical fracture stress is defined as DFS=2*Fmax/(Π*D*t) with Fmax being the tablet strength expressed as the force required to break a tablet when it is applied on its circumference; D being the tablet diameter and t its thickness; and
ii) the package comprising an inner surface, at least one region of which bears an adhesive.

Tablets having a diametrical fracture stress of 10-40kPa have improved dissolution properties. The diametrical fracture stress of the tablet is linked to the compression stress used to form the tablet. By selecting a lower diametrical stress, a lower compression stress is required, making the tablet less dense and therefore exhibiting better dispersion and dissolution properties.
It was found that a tablet having a diametrical fracture stress of 10-25kPa exhibited good dissolution.
The diametrical fracture stress may be 10-20kPa. Such tablets exhibit even better dissolution properties.
One problem with tablets having a lower diametrical fracture stress exhibit mechanical fragility and therefore have an increased tendency to break up during transit/handling.
However the provision of an inner surface bearing adhesive means that any loose particulate matter such as crumbs or dust which have eroded or broken away from the solid phase of the tablet/s can adhere to the adhesive.
This prevents or at least reduces the loss of crumbs/dust during opening of the pack/dispensing.
Furthermore, the laundry treatment tablets, themselves, are more attached to the inner surface bearing the adhesive. When the package comprises more than one laundry treatment tablet, the tablets are less likely to move against each other within the package and so friction between the tablets is reduced. Therefore, the likelihood of tablet fracture and the amount of crumbs/dust created are reduced.
Also, if particulate matter from the first phase becomes attached to the smooth phase this can detract from the appearance of the smooth phase, by dulling any shininess and/or translucence or transparency. It can also reduce the visual contrast between the two phases, thereby reducing the visual cue to the consumer that there are two distinct layers, each having a different composition function.
Adhesion of crumbs and dust to the adhesive layer prevents or at least reduces the amount of crumbs/dust which can adhere to the smooth phase.

The package

The package maybe rigid or flexible.
The package may comprise one or more seals which may be sealed using adhesive. The adhesive employed may comprise natural rubber latex and/or synthetic polymer dispersions. The sealing adhesive may be used e.g. expanded to provide at least one region of the invention. Preferably, the package is a film package such as a flow pack or flow wrap pack, comprising a tubular film bag with one longitudinal seam and two transverse seams.
Preferably the film has an moisture vapour transfer rate of 1-20 g/m²/day and more preferably 1-10 g/m²/day in order to protect the tablets which are hydroscopic individual or groups of tablets are packaged corresponding with a unit dose.
In a preferred embodiment tablets are packaged in pairs, and more preferably side by side.
The adhesive may be located on a region or regions of the inner surface of the packaging which is adjacent the solid phase. This enables the adhesive to pick up the dust/debris from the solid phase before it reaches the smooth phase.
Additionally, there may be adhesive on a region or regions adjacent the smooth phase.
The adhesive may be applied to the inner surface of the packaging material before it is formed into the package e.g. flow-wrap. The packaging material may also comprise a release lacquer on its outer surface to enable storage of the packaging material prior to the formation of the package. The release lacquer may comprise a solvent based polyamide and will prevent layers of the packaging material sticking during storage of the film wound on a real. Alternatively the adhesive may be applied during the forming of the package. The adhesive may be used to form the longitudinal seal of a flow wrap package.
In this case the adhesive may be applied longitudinally (corresponding to the longitudinal seal) and/or at successive points transversely (corresponding to the end seals) of the flow wrap packaging material, whereby the region/s is/are located and/or dimensioned relative to the final configuration such that region or regions of adhesive remain exposed internally of the package, after the forming process. These exposed regions provide the at least one region bearing adhesive of the invention.
Preferably the laundry treatment tablet of the invention cleans, softens and/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 (which maybe square or rectangular in cross section. 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 comprise 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 First 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 is transparent or translucent.
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 the 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 semi-solid 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 75°C, most preferred above 80°C or even above 90 °C.
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 Second Solid Phase

The lower diametrical fracture stress of the second solid phase means that the level of dispersion aids can be set more freely, leaving room within the tablet formulation for increased levels of other active agents.
Preferably, the diametrical fracture stress is 10-30kPa.
Because the tablet is not as dense and more prone to breaking up during filling, the amount of disintegrating agents such as water swellable polymers can be reduced. The amount of such polymers, such as sodium carboxymethyl cellulose SCMC, is preferably less than 0.5% and even more preferably less than 0.1% and more preferably 0%.
Similarly the level of disintegrants may be less than 5%, preferably less than 0.5%, more preferably less than 0.1% and even more preferably 0%.
It is preferred to use a tablet having less than 45% by weight of phosphate or poly-phosphate compounds, more preferably less than 30% even more preferably less than 15 and most preferably 0% of phosphate or poly-phosphate compounds. Reducing the level of phosphate or poly-phosphate makes the tablet more environmentally acceptable.
Dispersants may be provided in the form of disintegrating-promoting particles. Such particles typically contain at least 40% (of their own weight) of one or more:

compounds with a water-solubility exceeding 50 grams per 100 grams water
water swellable materials such as for example cellulose, cross-linked polyethylene glycol, cross linked polyvinyl pyrrolidone or an acrylic/maleic copolymer
phase I sodium tripolyphosphate
sodium tripolyphosphate which is partially hydrated so as to contain water of hydration in an amount which is at least 0.5% by weight of the sodium tripolyphosphate in the particles.

The total quantity of disintegration-promoting particles may be less than 5%wt and preferably less than 1% and more preferably 0% of the tablet.
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.
The second phase may comprise 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 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%. 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 C₈-C₁₅; 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 (C_8-22) phenol-ethylene oxide condensates, the condensation products of linear or branched aliphatic C_8-20 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 C_9-11 and C_12-15 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. xH₂O
These materials contain some bound water (indicated as AxH2O≅) 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-Na₂SiO₅ 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+1.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-6-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 plan view from the base of a package of tablets according to the invention;
Figure 2 is a perspective view of the package of fig 1.

Referring to fig 1, there is illustrated a flow wrap package 1 containing a pair of laundry tablets 3.
The flow wrap package 1 comprises a tubular plastic film bag having a longitudinal seal 5 and transverse end seals 7.
The longitudinal seal 5 is bounded on both sides by longitudinal strips of adhesive 9 (not shown in fig 2).
The tablets 3 comprise two discrete phases:

a smooth phase 13 and a solid phase 11.

The solid phase 11 comprises compacked particulate material. The smooth phase is a translucent gel.
The tablets 3 are oriented within the package 1 so that they are adjacent the longitudinal seal and adhesive strips 9. In this way the strips collect any debris and/or dust which erodes/breaks away from the solid phase (during packaging and transit) and prevents it from adhering to the smooth phase 13.
The adhesive is used in the formation of the flow-wrap. In this way an extra adhesive apply step is not necessary in the flow-wrap manufacturing process. This process essentially comprises the formation of a film tube from a strip of plastic film which is wrapped and sealed longitudinally. The tube is then sequentially filled (with tablets) transversely sealed and cut to provide individual packages.
With the invention the longitudinal seal is formed using a pressure sensitive adhesive applied in a wide band longitudinally of the film strip.
The adhesive band 9 is wide enough such that alter the longitudinal (fin) seal 5 is formed the seal 5 is bordered on each side by adhesive 9.
The transverse seals on also formed by adhesive.
In an alternative embodiment the package seals could be formed by heat sealing and the adhesive applied prior to the sealing process.
There may be a combination of heat/adhesive sealing e.g. longitudinal adhesive sealing and transverse heat sealing.
An exemplary laundry treatment tablet formulation is as follows:

A detergent powder was made of the following composition:
A detergent base powder, incorporating organic surfactants, a small percentage of crystalline sodium acetate trihydrate, and zeolite MAP was made using known granulation technology. It had the following composition, shown as parts by weight.

Ingredient	Parts by Weight
Sodium linear alkylbenzene sulphonate	20.85
nonionic surfactant (C13-15 branched fatty alcohol 3EO)	3.07
nonionic surfactant C13-15 branched fatty alcohol 7EO)	5.98
Soap	1.62
zeolite A24	46.70
Sodium acetate trihydrate	5.92
Sodium carbonate	6.60
sodium carboxymethyl cellulose (SCMC)	0.64
additional moisture and minor ingredients	8.50
Total	100

The amount of zeolite MAP (zeolite A24) in the table above is the amount which would be present if it was anhydrous. Its accompanying small content of moisture is included as part of the moisture and minor ingredients.
The base powder and other ingredients were mixed together as set out in the following table.

Comp A.
Base powder, as above	57.18
Antifoam (1)	2.30
Fluorescer (2)	1.59
Sodium percarbonate	19.23
TAED (3)	6.48
Sodium disilicate	4.07
Soil release polymer (4)	1.40
Acrylic/maleic copolymer (5)	1.53
EDTM phosphonate 0.95 Colored speckles	1.77
Cellulosic swelling disintegrant (6)	3.50
Total	100

Wherein:
(1) Antifoam is 17%wt silicon oil, 71%wt sodium carbonate and the remainder petroleum jelly and phosphate ester.
(2) Fluorescer is 9.9%wt Fluorescer and 82.5%wt sodium carbonate the remainder being minor ingredients
(3) TAED is 83%wt TAED in 9%wt sodium sulphate the remainder being minor ingredients.
(4) Soil release polymer is 18%wt soil-release polymer, 44%wt zeolite MAP, 21%wt sodium carbonate and minor ingredients.
(5) Acrylic/maleic polymer is Sokolan CP5 ex BASE (91%wt active) (6) Cellulosic swelling disintegrant (Arbocel ex Rettenmaier)

The solid phase was made by mixing the ingredients (except for the cellulosic swelling disintegrant) and finally adding the cellulosic swelling disintegrant.
The solid phase was made in a labscale Graseby Specac tabletting press; and had a strength (expressed in terms of the diametrical fracture stress) of approximately 25k Pa. The diametrical stress is defined as DFS=2*Fmax/(Π*D*t) with Fmax being the tablet strength expressed as the force required to break a tablet when it is applied on its circumference. D the tablet diameter and t its thickness.
A second exemplary solid phase formulation is exactly as for the above formulation an except that the level of the cellulosic swelling disintegrant is to 1.75% wt (and the base powder increased to 58.93% wt of the final formulation.
Smooth or semi-solid parts were prepared of the following composition:

Ingredient Composition Parts by wt

Na-las 57.5

Nonionic(Lutensil AO5) 46.1

Soap (Pristerene4916 )* 5

Dipropyleneglycol 30

Solvent Water 10.7

Notes: * is a C16-C18 soap;
The mixture semi solid part composition was heated to 80°C and cast into moulds and cooled to 20°C to form firm, 5 grammes smooth and semi-solid parts of 32mm diameter and 6mm high.
Multi-layer tablets are made by pre-compressing 25 grammes of the powdered composition in a die of 45 mm diameter at 4 kN/cm², followed by adherence of a smooth and semi-solid part on top of the compressed layer followed by a final compression step at 0.1 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.
After the final compression step the diametrical fracture stress of the second solid phase is still less than 30kPa.
Tablet shake tests (as described below) were conducted on various flow wrap constructions:

A Heat-sealed flow wrap (comparative example)
B Metallized cold-sealed flow wrap with adhesive
C Transparent cold-sealed flow wrap with adhesive

A' Heat-sealed flow wrap (comparative example)
B' Metallized cold-sealed flow wrap with adhesive
C' Transparent cold-sealed flow wrap with adhesive

Each flow wrap contained two laundry treatment tablets having a composition according to the exemplary formulation described above. The tablets were placed side by side within the package.
A, B and C contained tablets orientated such that the solid phase of the tablets were adjacent to the longitudinal seal and strips of adhesive.
A', B' and C' contained tablets orientated such that the smooth phase of the tablets were adjacent to the longitudinal seal and strips of adhesive.

TABLET SHAKE TEST

The test comprised the steps of:

i) fixing the flow wrap between two clamps at a distance of 10.5 cm; and
ii) shaking the flow wrap with the tablets at a fixed speed of 240 strokes per minute and an amplitude of 2.5cm for one to two minutes.

The results of the tablet shake test were as follows:

	Flow wrap construction and tablet orientation	Results
A*	heat-sealed flow wrap solid phase adjacent longitudinal seal of flow wrap	Within a few seconds fines released. These were deposited on smooth phase of tab.
B	metallized cold-sealed flow wrap	Smaller amount of fines released during shaking, compared to A, due to the fact that the tablets are more attached to the flow wrap. Majority became attached to adhesive bounding longitudinal seal. Very few fines deposited on smooth phase of tab.
	solid phase adjacent longitudinal seal of flow wrap
C	transparent cold-sealed flow	Smaller amount of fines
	wrap	released during shaking, compared to A, due to the fact that the tablets are more attached to the flow wrap. Majority became attached to adhesive bounding longitudinal seal. Very few fines deposited on smooth phase of tablet.
	solid phase adjacent longitudinal seal of flow wrap
A'*	heat-sealed flow wrap smooth phase adjacent longitudinal seal of flow wrap	Within few seconds fines released. These were deposited on smooth phase of tablet.
B'	metallized cold-sealed flow wrap	Slightly more fines deposited on edge of smooth phase of tablet compared with B. Still significantly less than A and A'.
	smooth phase adjacent longitudinal seal of flow wrap
C'	transparent cold-sealed flow wrap	Slightly more fines deposited on edge of smooth phase of tablet compared with C. Still significantly less than A and A'.
	smooth phase adjacent longitudinal seal of flow wrap

* comparative examples

The tablet shake test demonstrates that cold-sealed flow wraps with adhesive, examples B, C, B' and C', are more effective in reducing the amount of visible fines deposited on the smooth phase of the laundry treatment tablet compared with heat-sealed flow wraps, comparative examples A and A'.
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 washing machine.
A dispensing device, such as a net bag may be used.

Claims

One or more laundry treatment tablets in combination with a package wherein the one cr more laundry treatment tablets are packaged individually or in groups corresponding with a unit dose,
i) the one cr 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 comprising compacted particulate material and having a diametrical fracture stress [DFS] of 10-40kPa wherein diametrical fracture stress is defined as DFS = 2*Fmax/( Π*D*t) with Fmax being the tablet strength expressed as the force required to break a tablet when it is applied on its circumference; D being the tablet diameter and t its thickness; and

ii) the package comprising an inner surface, at least one region of which bears an adhesive.
A combination according to claim 1, wherein the laundry treatment tablet cleans, softens or freshens the laundry fabrics.
A combination according to claims 1 or 2, wherein the second phase of the laundry treatment tablet is a layer of compacted particulate material.
A combination according to any preceding claim wherein the region(s) of adhesive is/are located adjacent to the solid phase.
A combination according to any preceding claim wherein the package comprises a longitudinal seal bounded on at least one side by the or each region of adhesive.
A combination according to any preceding claim wherein the package comprises transverse end seals, at least one of which is bounded on at least one side by the or each region of adhesive.