EP1568762A1

EP1568762A1 - Detergent tablet compositions and their manufacture

Info

Publication number: EP1568762A1
Application number: EP05075025A
Authority: EP
Inventors: H.F.J. Hommes; Lammert Nauta; Peter Iwan Stuut
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2004-02-19
Filing date: 2005-01-07
Publication date: 2005-08-31

Abstract

A cleaning tablet comprising a first compressed particulate phase and a second smooth phase, the second smooth phase being bonded to another part of the tablet by means of a melt adhesive which is at least partially fused with the smooth phase.

Description

Fields of the Invention

The present invention relates to detergent compositions in the form of tablets for use in fabric washing and methods of making those tablets. Such tablets have the advantage that they do not require the user to measure out a volume of powder or liquid. Instead, one or more tablets provide an appropriate quantity of composition for washing a single load in the washing machine, or possibly by hand. They are thus easier for the consumer to handle and dispense.

Background of the Invention

Recently, a development in the detergent tablet market has involved the production of so-called multi-phase tablets, particularly those which comprise at least two phases comprising solid and gel-type phases as separate physical parts of the tablet.
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.
In such a tablet, the gel and solid phase sections of the tablet need to be bonded. The two parts need to be bonded with a material which is compatible with the compositions of both phases being bonded, and which is strong and stable with storage over time and at a variety of temperatures. Further, if the bonding is effected using a conventional adhesive, this will not contribute to tablet wash performance.
It has now been found that these problems can be solved by means of a melt adhesive, and in some cases a functional melt adhesive.
WO-A-00/52127 discloses bonding of segments of a tablet using a melted wax. However, this is not a functional ingredient, nor is it fused with another component in the tablet.

Definition of the Invention

A first aspect of the present invention comprises a cleaning tablet comprising a first compressed particulate phase and a second smooth phase, the second smooth phase being bonded to another part of the tablet by means of a melt adhesive which is preferably at least partially fused with the smooth phase.
A second aspect of the invention provides a cleaning tablet comprising a first compressed particulate phase and a second smooth phase, the second smooth phase being bonded to another part of the tablet by means of a melt adhesive comprising at least 50% of a soap.
A tablet according to the first aspect of the present invention optionally may fulfil the requirements of a tablet according to the second aspect of the present invention and vice versa.
A third aspect of the present invention provides a method of making a cleaning tablet, the method comprising providing a first compressed particulate phase and a second smooth phase, forming a tablet comprising said first and second phases, whereby the second smooth phase is bonded to another part of the tablet with a melt adhesive applied at a temperature such that the melt adhesive at least partially fuses with the smooth phase.

DETAILED DESCRIPTION OF THE INVENTION

The regions of a multi-phase 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.
In accordance with the first aspect of the invention, and preferably also in accordance with the second aspect, the melt adhesive preferably at least partly fuses with the smooth phase. However, it may bond to any other phase, such as the optional soap rich phase described in more detail hereinbelow, provided that in the case of the first aspect of the invention preferably, it also fuses with the smooth phase.
As used herein, reference to fusing refers to intermingling, eg physical interpenetration or substantially total molecular mixing of some or all components from two adjacent phases or segments.
Cleaning tablets of any aspect of the present invention may be formulated for any desirable application. Typical examples are laundry (fabrics) cleaning and mechanical warewashing (dishwashing). A typical laundry cleaning tablet comprises at least one surfactant selected from anionic and nonionic surfactants, together with at least one detergency builder. A typical mechanical warewashing tablet comprises nonionic surfactant, detergency builder and at least one enzyme.
Preferably tablets of the invention are of cylindrical shape wherein the two main surfaces (upper side and bottom side) are substantially flat.

The Compressed Particulate Phase

The compressed particulate phase is essentially a tablet portion comprising granular and/or simple powder material compressed into a solid mass. Typically, it will comprise surfactant, preferably also detergency builder and more preferably one or more other ingredients selected from the classes of ingredients used in solid cleaning compositions, especially laundry wash compositions (although other cleaning composition types such as mechanical wavewashing compositions are also possible). Such other optional classes of ingredients may for example be selected from enzymes, bleaches and bleach systems, fluorescers, anti-foams, anti-dye transfer agents, anti-redeposition agents, disintegrants and coloured speckles.
Although the first region of the compressed particulate phase may comprise surfactant materials, this region preferably comprises ingredients of the tablet other than surfactants. Examples of these ingredients are for example builders, bleach system, enzymes etc. Preferably the builders in the tablet are predominantly present in this first compressed particulate phase. Preferably the bleach system is also predominantly present in the second region. Preferably the enzymes are predominantly present in the second smooth region. For the purpose of this invention, unless stated otherwise, the term "predominantly present" refers to a situation wherein at least 90 wt% of an ingredient is present in the second region, more preferred more than 98 wt%, most preferred substantially 100 wt%.
Preferably the first compressed particulate phase is from 5 to 50 grammes, for example 10 to 40 grammes. Especially preferably the regions are present as layers in the cleaning tablet.
A compressed particulate phase is 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.
Tableting to make a compressed particulate phase entails compaction of a particulate composition.
A variety of tableting machinery is known, and can be used. Generally it will function by stamping a quantity of the particulate composition which is confined in a die.
Manufacture of a tablet with two layers of differing composition may be carried out by placing a predetermined quantity of one composition in a mould, then adding a second composition on top, and next driving a die into the mould to cause compression.
Alternatively, a predetermined quantity of a first composition may be placed in a mould and compacted by driving a die into the mould, followed by removing the die, adding a second composition and compacting again.
Tableting machinery able to carry out such operations is known. For example, suitable tablet presses are available from Fette and from Korsch.
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.
It is known to make tablets using microwave radiation. WO 96/06156 mentions that hydrated materials are useful in this special circumstance to cause sintering.
For the present invention, if any heat is supplied, it is envisaged that this will be supplied conventionally, such as by passing the particulate composition through an oven, rather than by any application of microwave energy.
The size of a tablet will suitably range from 10 to 160 grams (gm), preferably from 15 to 60 gm, depending on the conditions of intended use, and whether the tablet represents a dose for an average load in a fabric washing 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 is preferably 1040 or 1050 gm/litre, better 1100 gm/litre, up to 1300 or 1350 gm/litre or even more. The tablet density may well lie in a range up to no more than 1250 or even 1200 gm/litre.
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 advantageously at least 700 g/litre. Granular detergent compositions of high bulk density prepared by granulation and densification in a high-speed mixer/granulator, as described and claimed in EP 340013A (Unilever), EP 352135A (Unilever), and EP 425277A (Unilever), or by the continuous granulation/densification processes described and claimed in EP 367339A (Unilever) and EP 390251A (Unilever), are inherently suitable for use in the present invention.
Preferred embodiments of the invention will now be described by way of example only. Further modification within the scope of the present invention will be apparent to the person skilled in the art.

The 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.
The smooth region of the tablet may also contain diluent materials for example polyethyleneglycol, dipropyleneglycol, isopropanol or (mono-)propyleneglycol. Preferable the level of these diluents is from 0 to 40 wt%, more preferred 1 to 20, most preferred from 4 to 15 wt% based on the weight of the smooth phase.
The smooth phase comprises no or only low levels of water. Preferably the level of water is less than 20 wt % based on the weight of the smooth phase, more preferred less than 15 wt%, most preferred from 5 to 12 wt%. Most preferably the smooth 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.
Preferably the smooth phase is transparent or translucent. Preferably, this means that the composition has an optical transmissivity of at least 10%, most preferably 20%, still more preferably 30%, through a path length of 0.5 cm at 25° C. These measurements may be obtained using a Perkin Elmer UV/VIS Spectrometer Lambda 12 or a Brinkman PC801 Colorimeter at a wavelength of 520nm, using water as the 100% standard.
The transparency or translucency of the compositions according to the invention does not preclude the composition being coloured, e.g. by addition of a dye, provided that it does not detract substantially from clarity.
In an advantageous embodiment of the invention the smooth phase comprises from 30-100 wt% of non-soap surfactants, more preferred 40 to 90 wt% (based on the total weight of said smooth phase), more preferred from 50 to 80 wt%. It has been found that the combination of a separate smooth first region and these high non-soap surfactant levels provide very good dispersing and cleaning properties to the tablet.
Preferably the total weight of surfactants in the smooth phase is from 2 to 20 grammes, more preferred from 3 to 10 grammes.
The non-soap surfactants in said third smooth phase may for example be anionic, nonionic or cationic non-soap surfactants or mixtures thereof. Relatively low levels of soap may also be present, for example up to 10 wt% based on said second smooth phase.
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 Melt Adhesive

The melt adhesive comprises one or more melt adhesive materials. These may be selected from hot melt adhesives and/or soaps especially meltable soaps. The latter soaps are essential in the case of the second aspect of the invention. Preferably the level of meltable soap in the melt adhesive is at least 50 wt%, more preferred more than 90%, preferably the melt adhesive is predominantly constituted by a meltable soap.
Preferably, the melt adhesive has a melting point of greater than 80°C, more preferably greater than 100°C and most preferably greater than 120°C. It s generally preferred that the melting point of the melt adhesive is less than 150°C, more preferred less than 120°C.
Preferred hot melt adhesives may be selected from one or more of the following polymers: poly-ethylene-glycols with an average mol weight from 1,500 to 20,000, sulphonated-polyesters or co-polyesters, poly-vinyl-alcohols, fenoplasts or aminoplasts (which are based on chemical reaction between formaldehyde, phenol, urea, melamine), poly-vinyl-pyrrolidones, poly-vinyl-acetates, ethylene-vinyl acetates, polyolefin resins, polyamide, polyester resins, acrylics, butylene glycols and thermoplastic elastomers.
Preferred meltable soaps are pure or mixtures from saponified fats and oils with a carbon chain from C₆ to C₂₂ (Caproic, Caprylic, Capric, Lauric, Myristic, Palmitic, Palmitoleic, Stearic, Oleic, Linoleic, Linolenic, Conjugated, Arachidic, Gadoleic, Behenic, Erucic) with water, polyols (di-propylene-glycol, mono-propylene-glycol) and surfactant mixtures as solvents. Additionally other non-soap surfactants may be added up to 80-90%, like non-soap anionic surfactants, nonionic surfactants or cationic surfactants.
The melt adhesive may have substantially the same composition as the smooth paste.

Optional Soap Rich Phase

Preferably, a cleaning table of the present invention comprises no only the first compressed particulate phase and second smooth phase, it also comprises a third, soap rich phase.
If the tablet is a multi-phase tablet comprising the soap rich phase, then preferably the soap rich phase is present as a distinctive region preferably having a weight of from 1 to 40 grammes, more preferred from 2 to 20 grammes, most preferred from 2 to 10 grammes. Preferably the other phases each have a weight of 2 to 40 grammes. Preferably the total weight of the cleaning tablet according to the invention is from 10 to 50 grammes.
For the purpose of the invention the term soap rich phase refers to a separate part of the tablet e.g. a region such as a layer wherein the level of soap is high, for example from 40 to 100 wt%, more preferred the soap level is at least 50 wt% and can even be very high say more than 80wt% or even more than 90 wt% up to 100 wt% based on the weight of the soap rich phase. Other ingredients may also be present in the soap rich layer, although preferably the soap rich layer is substantially free of non-soap surfactants, bleach ingredients and builder materials. Sometimes it may be advantageous however to incorporate into the soap rich layer a highly soluble material such as sugars, urea, alkali metal salts such as soidum chloride etc. Typically such highly soluble materials will have a solubility of at least 100 grammes per litre water of 20 C, more preferred at least 250 grammes. Advantageously the level of these highly soluble materials in the soap rich phase is less than 50 wt%, for example from 5 to 45 wt%, advantageously from 10 to 40 wt%.
The soap rich region of the tablet may be prepared by any suitable method for example the spraying, applying or brushing of a soap rich formulation, if appropriate followed by hardening e.g by cooling. In a preferred method the soap rich layer is obtained from the compression of soap rich particles. Such detergent particles preferably comprise at least 50 wt% (based on the particles) of soap surfactants. Suitable detergent particles may for example be granules or other particles having high soap levels, for example soap noodles, marumes or granulates with high soap levels.
Preferably the level of soap surfactants in the soap rich particles is more than 50 wt%, more preferred more than 70 wt%, especially preferred from 75 wt% to 100 wt%. Preferably the level of soap rich particles in the soap rich phase is at least 60 wt%, more preferred from 80 to 100 wt%.
Further surfactants, for example anionic, nonionic or cationic surfactants may equally be present in the soap rich phase for example at a level of 0.1 to 10 wt% based on the weight of the soap rich part. However normally the first soap rich phase will be substantially free from non-soap surfactants.
In addition to the soap surfactants the soap rich region may comprise other materials for example soluble materials such as electrolyte materials, meltable organic materials and sugars, at a level of 2 to 70 wt% based on the weight of the smooth part, more preferred from 3 to 50 wt%, most preferred 5 to 40 wt%. Examples of preferred materials are water-soluble materials such as the sodium and potassium citrates, sodium chloride, acetates and carbonates, urea and sugar. The water solubility at 20 C of these materials is preferably at least 10 grammes per 100 ml of water, more preferred more than 15 grammes, most preferably more than 20 grammes.
If these soluble materials are present, their particle size is preferably chosen such that the soap rich phase is a soap rich continuous matrix having dispersed therein particles of the water soluble material.
It has been found that these materials provide good dissolution properties to the soap rich phase. Furthermore these materials do not negatively affect the desired firm consistency of the soap rich phase.
The optional soap rich and compressed particulate phase are joined by the virtue of being formed by co-compression.
Preferably the (co-)compression of the combination of the soap rich and the solid region(s) takes place at a force of from 0.05 to 20 kN/cm². Especially if the solid region has been pre-compressed the co-compression in step (c) can advantageously be at a force of 0.1- 10 kN/cm², more preferred 0.5 to 5 kN/cm². If the solid region has not been pre-compressed, the co-compression preferably takes place at a force of 1- 100 kN/cm²., more preferred 2-50 kN/cm²., most preferred 2-10 kN/cm².
If the tablet of the invention comprises a soap-rich phase as described above, this phase may also be manufactured seperately by compression of a particulate soap rich material e.g. at the compation forces as indicated above.
Alternatively any soap rich phase may be prepared by other methods for example the spraying of a soap rich composition for example onto the (pre) compressed compacted tablet phase. Another suitable method for the preparation of a soap rich phase may involve casting or extrusion of a soap rich composition.
Optionally the smooth (preferably non-soap surfactant) phase may also be prepared e.g. by extrusion, casting or other shaping methods.
Seperately prepared soap rich phase and any soap surfactant rich phase can then be adhered to other parts of the tablet for example by gentle pressing or by usage of an adhesive material.
Similarly, the compressed particulate phase can be combined with one ore more pre-prepared soap rich phases e.g. by gentle co-compression.
A tablet of this invention may be intended for use in machine dishwashing. Such tablets will typically contain salts, such as over 60 wt% of the tablet.
Water soluble salts typically used in machine dishwashing compositions are phosphates (including condensed phosphates) carbonates and silicates, generally as alkali metal salts. Water soluble alkali metal salts selected from phosphates, carbonates and silicates may provide 60 wt% or more of a dishwashing composition.
Another preferred possibility is that a tablet of this invention will be intended for fabric washing. In this event the tablet will be likely to contain at least 2 wt%, probably at least 5 wt%, up to 40 or 50 wt% soap or non-soap surfactant based on the whole tablet, and from 5 to 80 wt% detergency builder, based on the whole tablet.
Materials which may be used in tablets of this invention will now be discussed in more detail.

Disintegrants

Preferably, the first compressed solid phase comprises one or more disintegrants.
Preferred disintegrants are materials which have a solubility in (preferably deionised) water at 20°C of at least 50 grams per 100 grams of water.
This disintegrant may be present in an amount which is at least 5wt%, 7 wt% or 12 wt% of the tablet. Some of the disintegrant may be present in the base powder used to make the complete tablet formulation used for the second zone, whilst the remainder, preferably the majority, is added as a post-dosed ingredient to the base powder before tableting in the second zone. It is preferred that at least 75wt% or even 85wt% of the material is not in the base powder, but is added as a post-dosed ingredient.
A solubility of at least 50 grams per 100 grams of water at 20°C is an exceptionally high solubility: many materials which are classified as water soluble are less soluble than this.

Some highly water-soluble materials which may be used are listed below, with their solubilities expressed as grams of solid required to form a saturated solution in 100 grams of water at 20°C:-

Material	Water Solubility (g/100g)
Sodium citrate dihydrate	72
Potassium carbonate	112
Urea	>100
Sodium acetate (anhydrous)	119
Sodium acetate trihydrate	76
Magnesium sulphate 7H₂O	71
Potassium acetate	>200

By contrast the solubilities of some other common materials at 20°C are:-

Material	Water Solubility (g/100g)
Sodium chloride	36
Sodium sulphate decahydrate	21.5
Sodium carbonate anhydrous	8.0
Sodium percarbonate anhydrous	12
Sodium perborate anhydrous	3.7
Sodium tripolyphosphate anhydrous	15

Preferably this highly water-soluble disintegrant is incorporated as particles of the material in a substantially pure form (i.e. the majority of such particles contain over 95% by weight of the material). However, the said particles may contain material of such solubility in a mixture with other material, provided that material of the specified solubility provides at least 50% by weight of these particles.
The preferred disintegrant of high water-solubility are sodium citrate dihydrate, potassium carbonate, urea, sodium acetate in its anhydrous or trihydrate form, sodium acetate which is partially hydrated - as can be the case when it is spray dried, magnesium sulphate 7H₂O and potassium acetate. Mixtures of these can also be used. The most preferred of the aforementioned materials are sodium citrate dihydrate, sodium acetate in either its anhydrous, trihydrate or partially hydrated form. Mixtures of these most preferred materials can also be used.
Another suitable class of disintegrants comprises cellulose disintegrants.

Detergent-actives

As is apparent from the foregoing, cleaning tablets of this invention preferably contain one or more detergent-actives in one or more. In a fabric washing 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 25, 40 or 50% by weight. The detergent-active may be anionic (soap or non-soap), cationic, zwitterionic, amphoteric, nonionic or any combination of these. Many suitable detergent surfactants are commercially available and are fully described in the literature, for example in "Surface Active Agents and Detergents", Volumes I and II, by Schwartz, Perry and Berch.
Anionic surfactant is present in an amount of from 0.5 to 40% by weight, preferably from 2% or 4% up to 20%, 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 chain 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 100wt% of any anionic non-soap surfactant in the composition.
In some forms of this invention the amount of non-soap anionic detergent lies in a range from 5 to 20wt% of the tablet composition.
It may also be desirable to include one or more soaps of fatty acids. These are preferably sodium soaps derived from naturally occurring fatty acids, for example, the fatty acids from coconut oil, beef tallow, sunflower or hardened rapeseed oil.
Suitable nonionic detergent 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 either alone or with propylene oxide.
Specific nonionic detergent 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. Other nonionic detergent compounds include alkylpolyglycosides, long-chain amine oxides, tertiary phosphine oxides, and dialkyl sulphoxides.
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 certain forms of this invention the amount of nonionic detergent lies in a range from 4 to 40wt%, better 4 or 5 to 30wt% by weight of the composition.
Many nonionic detergent-active compounds are liquids. These may be absorbed on a porous carrier or on particles of the composition. Preferred carriers include zeolite; zeolite granulated with other materials, for example Wessalith CS (Trade Mark), Wessalith CD (Trade Mark) or Vegabond GB (Trade Mark); sodium perborate monohydrate; Burkeite (spray-dried sodium carbonate and sodium sulphate as disclosed in EP-A-221776 of Unilever); and layered sodium silicate as described in US-A-4664839.
Amphoteric or zwitterionic detergent compounds may also be used in the compositions of the present invention, but this is not normally desired due to their relatively high cost. If any amphoteric or zwitterionic detergent compositions are used it is generally in small amounts in compositions which are based on the much more commonly used synthetic anionic and/or nonionic detergent compositions.

Detergency Builder

Any detergency builder is preferably present in an amount of 15wt%-70wt%, more preferably from 15 to 60wt%, e.g. 20-55wt%. Especially preferred are compositions comprising 15 to 60wt% of water-insoluble detergency builder.
The detergency builder may be provided wholly by water-soluble materials, or may be provided in large part or even entirely by water-insoluble materials with water-softening properties.
Alkali-metal aluminosilicates are strongly favoured as environmentally acceptable water-insoluble builders for fabric washing. Alkali metal (preferably sodium) aluminosilicates may be either crystalline, 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 "xH₂O") and are required to have a calcium ion exchange capacity of at least 50 mg CaO/g. The preferred sodium aluminosilicates within the above formula contain 1.5-3.5 SiO₂ units. Both amorphous and crystalline aluminosilicates can be prepared 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 "SKS-6"). NaSKS-6 has the delta-Na₂SiO₅ morphology form of layered silicate. It can be prepared by methods such as described in DE-A-3417649 and DE-A-3742043. Other such layered silicates, such as those having the general formula NaMSi_xO_2x+1.yH₂0 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 ortophosphates, 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.
Tablet compositions preferably include polycarboxylate polymers, more especially polyacrylates and acrylic/maleic copolymers which can function as builders and also inhibit unwanted deposition onto fabric from the wash liquor. Nitrilo triacetate may also be used as the builder. The trisodium salt is especially preferred.

Bleach System

Tableted detergent compositions according to the invention may contain a bleach system. 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), which is 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 detergent tablets of the invention may also contain 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 of a detergent composition to form a tablet.
The detergent tablets of the invention may also contain 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, especially if the detergent 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, sorbed 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.
The detergent tablets of the invention may also contain a perfume composition. The perfume composition will normally consist of a plurality of perfumery materials having a fragrance, and may include a minor proportion (less than 50% by weight of the perfume) of odourless organic solvent which serves as a carrier. Perfume compositions suitable for use in fabric washing have been disclosed in various documents including EP 332259 (Procter) and are available from perfume houses such as Quest International, Naarden, Netherlands. A perfume composition may have deodorant properties, as disclosed in US4304679, US4663068, US5501805 and US5554588.
The total amount of perfume in a tablet is likely to be from 0.1 to 5% by weight of the tablet, preferably from 0.1 to 2%. In many fabric washing products, the amount of perfume is less than 1%. The total amount of perfume in a tablet may therefore be in a range from 0.1 to 0.5%.
Further ingredients which can optionally be employed in the detergent tablet of the invention include anti-redeposition agents such as sodium carboxymethylcellulose, straight-chain polyvinyl pyrrolidone and the cellulose ethers such as methyl cellulose and ethyl hydroxyethyl cellulose, heavy metal sequestrants such as EDTA, and colorants or coloured speckles.

Fabric Softeners

In the context of the present invention, cleaning includes any activity which is auxiliary to the removal of soil, for example fabric softening. Laundry wash tablets or laundry softening compositions per se, may incorporate a fabric softener.
The total amount of fabric softening agents, including the amount of clay minerals, in the tablets of the invention will, in general, be from 0.5 or 3 wt% up to 30 or 50 wt% of the tablet. The lower limit may be as high as 5 wt% and the upper limit as low as 10 wt%.
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 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, e.g. 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 tablets of the present invention are:
(1) Acyclic quaternary ammonium compounds wherein two N-substituents are hydrocarbyl groups containing from 15 to 22 carbon atoms, the third N-substituent is a saturated alkyl or hydroxy alkyl group containing from 1 to 4 carbon atoms, and the fourth substituent may be defined as for either of the other substituents or may be phenyl. The counter-anion is 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 -OH, -O-, COHN, -COO- etc.Representative examples of these quaternary softeners include ditallow dimethyl ammonium chloride; di(hydrogenated tallow) dimethyl ammonium chloride; di(coconut) dimethyl ammonium chloride; di(coconut) dimethyl ammonium methosulphate.
(2) Ester Quaternary Ammonium Salts A number of quaternary ammonium salts containing ester groups, including those disclosed in FR-A-2054337 (BASF), EP-A-345842 A2 (Procter), EP-A-239910 (Procter) and US-A-4137180 (Lever) are suitable for use in the tablets of the present invention. Examples of suitable materials include N,N-di(tallowyl-oxyethyl), N-methyl, N-hydroxyethyl ammonium chloride and 1,2-ditallowyloxy-3-trimethyl ammoniopropane chloride. In these materials, tallowyl may be replaced with cocoyl, palmoyl, lauryl, oleyl, stearyl and palmityl groups.
3) Quaternary Imidazolinium Salts A further class of cationic softener materials is the imidazolinium salts of generic formula (I)
wherein Q₁₁ is a hydrocarbyl group containing from 6 to 24 carbon atoms, G is -N(H)-, or -O-, or -NQ₂-, n is an integer between 1 and 4, and Q₂ and Q₆ are as defined above.Preferred imidazolinium salts include 1-methyl-1-(tallowylamido) ethyl-2-tallowyl-4,5 dihydro imidazolinium methosulphate and 1-methyl-1-(palmitoylamido) ethyl-2-octadecyl-4,5-dihydroimidazolinium chloride. Other useful imidazolinium materials are 2-heptadecyl-1-methyl-1-(2 stearylamido) ethyl imidazolinium chloride and 2-lauryl-1-hydroxyethyl-1-oleyl imidazolinium chloride. Also suitable are the imidazolinium fabric softening components of US 4127489.
4) Primary, Secondary and Tertiary Amines. Primary, secondary and tertiary amines are useful as softening agents. One N-substituent is a hydrocarbyl group containing from 6 to 24 carbon atoms, the second N-substituent is hydrogen or a hydrocarbyl group containing from 1 to 22 carbon atoms and the third N-substituent can be hydrogen or a hydrocarbyl group containing from 1 to 6 carbon atoms. Preferably amines are protonated with hydrochloric acid, orthophosphoric acid or citric acid or any other similar acids for use in cleaning compositions of the present invention. Specific examples of tertiary amines that are suitable for use in the tablets of the present invention are those disclosed in EP
213720 (Unilever).
5) Cellulase British Patent Specification GB 1 368 599 (Unilever) discloses the use of cellulolytic enzymes, i.e. cellulases, as harshness reducing agents. It is thought that cellulase achieves its anti-harshening effect on, e.g. cotton, by cleaving the cellulosic fibrils which form on the cotton fibres during the normal washing process. This cleavage prevents the fibrils from bonding together and thereby introducing a degree of rigidity into the fabric.
It is preferred to use cellulases which have an optimum activity at alkaline pH values, such as those described in British Patent Specifications GB 2 075 028 A (Novo Industrie A/S), GB 2 095 275 A (Kao Soap Co Ltd) and GB 2 094 826 A (Kao Soap Co Ltd).
Examples of such alkaline cellulases are cellulases produced by a strain of Humicola insolens (Humicola grisea var. thermoidea), particularly the Humicola strain DSM 1800, cellulases produced by a fungus of Bacillus N or a cellulase 212-producing fungus belonging to the genus Aeromanas, and cellulase extracted from the hepatopancreas of a marine mollusc (Dolabella Auricula Solander).
The amount of cellulase in a tablet of the invention will, in general, be from 0.1 to 10% by weight. In terms of cellulase activity the use of cellulase in an amount corresponding to from 0.25 to 150 or higher regular C_x units/gram of detergent composition is within the preferred scope of the present invention. A most preferred range of cellulase activity, however, is from 0.5 to 25 regular C_x units/gram of the detergent composition.
The present invention will now be better illustrated by way of the following non-limiting examples.

Examples

Example 1

I: first particulate composition

A powder was made of the following composition by pregranulating the granule ingredients, followed by post-dosing the rest of the ingredients

Ingredient	Parts by weight
Granules
Na-LAS	1.1
Nonionic 7EO	0.5
C12 soap	0.1
NaAc.3aq	0.3
Zeolite A24	2.4
Light soda ash	0.4
Moisture/minors	0.4
Post-dose
EAG (17% silicone)	3.0
Fluorescer (15%)	2.2
STP	62.4
Na-disilicate (80%)	3.8
TAED (83%)	4.3
Percarbonate	16.9
Dequest 2047	1.9
Minors/ enzymes/colour	to 100

Solid phase preparation
20 grammes of the of the first particulate composition are inserted into a 45 mm die of a tabletting machine, optionally followed by a flattening step. The whole material is compressed at 30kN into a single tablet.
Soap rich phase preparation 5 grammes of C12-C14 soap particles were dosed in the tablet mould on top of the solid phase, followed by a second compression step of 10 kN resulting in the formation of a first soap rich phase on top of the solid phase.

Non-soap surfactant rich smooth phase preparation
Smooth parts were prepared of the following composition:

Ingredient Parts by weight

Na-LAS 39.1

Nonionic 7EO 33.5

C12 soap 7.3

Monopropyleenglycol to 100
The mixture was heated to 80°C, cast into a cylinder of 1 meter long and a diameter of 45mm. After cooling of the smooth phase to room temperature the bar was cut into slices of 5 grams to form smooth, semi-solid parts of 45mm diameter.
The smooth phase and the powder tablet part were assembled by putting a droplet of 0.4 gram cycloflex 34-625A hotmelt onto the surface of the powder tablet at 140°C, directly followed by placing the smooth phase slice on top of the adhesive part. The smooth part was manually and gently pressed for 2 seconds to get good contact between smooth phase and adhesive.

Example 2

Instead of using the cycloflex hotmelt, a meltable soaps could be used as an adhesive. The same powder tablet part and smooth phase were used as in the previous example. The smooth phase and the powder tablet part were assembled by putting a droplet of 0.4 gram prisavon 2013 (ex Uniqema) meltable soap material onto the surface of the powder tablet at 95°C, directly followed by placing the smooth phase slice on top of the adhesive part. The smooth part was manually and gently pressed for 2 seconds to get good contact between smooth phase and adhesive.

Example 3

The same powder tablet part and smooth phase were used as in the previous example. The smooth phase and the powder tablet part were assembled by putting a droplet of 0.4 gram smooth phase material onto the surface of the powder tablet at 90°C, directly followed by placing the smooth phase slice on top of the adhesive part. The smooth phase used for adhesion of smooth phase and powder tablet part consisted of the following ingredients:

Ingredient Parts by weight

Na-LAS 39.1

Nonionic 7EO 33.5

C12 soap 7.3

Monopropyleenglycol to 100

Table: composition smooth phase used as adhesive
The smooth part was manually and gently pressed for 2 seconds to get good contact between smooth phase and adhesive

Determination of adhesive strength

In this test, a wedge shaped pressure head was used, which in a slow motion vertically moves between the gel and the tablet. By performing this action, the gel is slowly peeled off the tablet. From this action the maximum peel force (N), the peel energy (mJ) and the maximum displacement (mm) were determined.

Adhesive Peel energy [mJ]

Cycloflex 34-625A 18.3

Prisavon2013 19.2

Smooth phase 10.2

Claims

A cleaning tablet comprising a first compressed particulate phase and a second smooth phase, the second smooth phase being bonded to another part of the tablet by means of a melt adhesive.
A cleaning tablet according to claim 1 comprising a first compressed particulate phase and a second smooth phase, the second smooth phase being bonded to another part of the tablet by means of a melt adhesive comprising at least 50 wt% (based on said adhesive) of a soap.
A cleaning tablet according to claim 2, wherein the soap comprising adhesive has a melting point above 30°C, preferably more than 50°C, more preferably above 65°C, most preferably above 80°C.
A cleaning tablet according to claim 2 or claim 3, wherein the melt adhesive further comprises one or more synthetic surfactants selected from anionic, nonionic and/or cationic surfactants other than soap.
A cleaning composition according to claim 4, wherein the melt adhesive has substantially the same composition as the smooth phase.
A cleaning tablet according to claim 1, wherein the melt adhesive comprises a hot melt adhesive selected from one or more of the following polymers: poly-ethylene-glycols with an average mol weight from 1,500 to 20,000, sulphonated-polyesters or co-polyesters, poly-vinyl-alcohols, fenoplasts or aminoplasts (which are based on chemical reaction between formaldehyde, phenol, urea, melamine), poly-vinyl-pyrrolidones, poly-vinyl-acetates, ethylene-vinyl acetates, polyolefin resins, polyamide, polyester resins, acrylics, butylene glycols and thermoplastic elastomers.
A cleaning tablet according to either preceding claim, wherein the melt adhesive has a melting point above 80°C, preferably above 100°C, most preferably above 120°C
A cleaning tablet according to any preceding claim, wherein the melt adhesive is cold water dispersible or cold water soluble.
A cleaning tablet according to any preceding claim, wherein the smooth phase comprises less than 15wt%, more preferred from 5 to 12 wt% of water.
A cleaning tablet according to any preceding claim, for laundry cleaning, the tablet comprising at least one surfactant selected from anionic and nonionic surfactants and a detergency builder.
A cleaning tablet according to any of claims 1 - 8, for mechanical warewashing, the tablet comprising nonionic surfactant, detergency builder and an enzyme.
A method of making a cleaning tablet, the method comprising providing a first compressed particulate phase and a second smooth phase, forming a tablet comprising said first and second phases, whereby the second smooth phase is bonded to another part of the tablet with a melt adhesive applied at a temperature such that the melt adhesive at least partially fuses with the smooth phase.