EP1358311B1

EP1358311B1 - Cleaning compositions

Info

Publication number: EP1358311B1
Application number: EP02716699A
Authority: EP
Inventors: Jelles V. Unilever R & D Vlaardingen BOSKAMP; Ian Unilever R & D Vlaardingen CALLAGHAN; Somdath Unilever R & D Vlaardingen CHOENNIE; Paulus J. M. Unilever R & D Vlaardingen LOOMANS
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2001-02-05
Filing date: 2002-01-29
Publication date: 2011-08-17
Anticipated expiration: 2022-01-29
Also published as: EP1358311A1; ES2368134T3; ATE520768T1; WO2002062939A1

Abstract

The invention provides a tablet of compacted particulate detergent composition comprising non-soap surfactant and detergency builder and comprising;a) disintegrant granules comprising water insoluble inorganic material and water swellable agent which, in its anhydrous state, comprises no more than 20%wt of the combined weight of the inorganic material and the water swellable agent, and either; b) water-soluble disintegration-promoting particles containing at least 40%wt of the particles, of materials selected from compounds with water-solubility exceeding 50 grams per 100 grams water at 20OC or sodium tripolyphosphate containing at least 50% of its own weight of the phase I anhydrous form or being partially hydrated, orc) 10 to 60%wt of an aluminosilicate builder, and one or more detergency enzymes.The tablets show good disintegration properties

Description

FIELD OF THE INVENTION

The present invention relates to cleaning compositions in the form of tablets. These tablets are intended to disintegrate when placed in water and thus are intended to be consumed in a single use. The tablets may be suitable for use in machine dishwashing, the washing of fabrics or other cleaning tasks.

BACKGROUND OF THE INTENTION

Products in tablet form have several advantages over powdered products: for example, they do not require measuring and are thus easier to handle and dispense into the wash-load, and they are more compact, hence facilitating more economical storage.
Detergent compositions in tablet form and intended for fabric washing have been described in a number of patent documents including, for example WO-98/42817 and WO-99/20730 (all Unilever), and are now sold commercially. Tablets of composition suitable for machine dishwashing have been disclosed in WO-96/23530 and US-A-5691293 and are sold commercially.
Tablets of a cleaning composition are generally made by compressing or compacting a composition in particulate form. Although it is desirable that tablets have adequate strength when dry, yet disperse and dissolve quickly when brought into contact with water, it can be difficult to obtain both properties together. Tablets formed using a low compaction pressure tend to crumble and disintegrate on handling and packing; while more forcefully compacted tablets may be sufficiently cohesive but then fail to disintegrate or disperse to an adequate extent in the wash. Tabletting will often be carried out with enough pressure to achieve a compromise between these desirable but antagonistic properties. However, it remains desirable to improve one or other of these properties without detriment to the other so as to improve the overall compromise between them. US-A-3018267 (Procter & Gamble) taught that the force, and hence pressure, applied when compacting a composition into tablets should be limited, or else the tablets would take too long to dissolve.
If a tablet contains organic surfactant, this can function as a binder, plasticising the tablet. However, it can also retard disintegration of the tablet by forming a viscous gel when the tablet comes into contact with water. Thus, the presence of surfactant can make it more difficult to achieve both good strength and speed of disintegration: the problem has proved especially acute with tablets formed by compressing powders containing surfactant and built with insoluble detergency builder such as sodium aluminosilicate (zeolite) .
It is known to include highly soluble materials whose function is to enhance disintegration of tablets when placed in wash water. Some tablets which are sold commercially incorporate urea for this purpose.
EP-A-711 827 (Unilever ) teaches the use of sodium citrate for this purpose and EP-A-838519 (Unilever) teach the use of sodium acetate trihydrate for this purpose.
A number of documents have taught that the disintegration of tablets of cleaning composition can be accelerated by incorporating in the tablet a quantity of a water-insoluble but water-swellable material serving to promote disintegration of the tablet when placed in water at the time of use. Such documents include WO-98/40462(Rettenmaier ) and WO-98/40463 (Henkel ). DE 199 32 569 (Henkel ) discloses the use of auxiliary disintegrant agents of a fine particle size in machine dishwashing tablets.
Typical water-swellable agents which have been disclosed as possible tablet disintegrating agents are starches, cellulose and cellulose derivatives, alginates, dextrans, cross-linked polyvinyl pyrrolidones, gelatines and formaldehyde casein as well as a wide variety of clay minerals and certain ion-exchange resins.
Often these water swellable agents have no function in fabric washing except to aid tablet disintegration. Furthermore, because they are insoluble and of relatively large particle size, they tend to deposit on fabric during the wash; see for example WO-98/55575 (Henkel ). As a result, several attempts have been made to minimise the deposition of these disintegrants, for example by combining such a water swellable water soluble disintegrant with a second, highly soluble disintegration aid (see WO-98/55582 and WO-98/55590 both Unilever). Other attempts have included use of a preferred particle size of the disintegrant. For example, WO-98/55583 (Unilever ) discloses the use of such materials at a particle dimension of at least 400um to give more efficient disintegration. WO-98/55575 (Henkel ) however teaches the use of cellulose disintegrating aids with a particle size of less than 100 um in order to minimise deposition. For DE 199 01 063 , the cellulose material is mixed with a material of a given oil absorbing capacity, which includes some zeolites.
We have found that two different measures of tablet strength are relevant to properties observed by a consumer. Force to cause fracture is a direct assessment of strength and indicates the tablets' resistance to breakage when handled by a consumer at the time of use. The amount of energy (or mechanical work) put in prior to fracture is a measure of tablet deformability and is relevant to the tablets' resistance to breakage during transport. Both properties are relevant to consumers' perception of tablets: consumers want tablets to be strong enough to handle, to reach them intact, and to disintegrate quickly and fully at the time of use.
Thus, there is a need to provide a cleaning composition in the form of a tablet, which has adequate strength when dry so it withstands handling during manufacture, packaging, transport and storage, yet which disperses and dissolves in an acceptable time when brought into contact with a washing medium such as water, but, without causing the additional problem of unacceptable residues on the substrate being cleaned.

SUMMARY OF THE INVENTION

Surprisingly, we have now found that if a water swellable disintegrating aid is co-granulated with a water-insoluble inorganic material before being incorporated into a tablet, and, the disintegrant granule is used in a tablet comprising certain water-soluble disintegration-promoting particles, or, an aluminosilicate builder and an enzyme, then the disintegration granule is more effective. Less of the disintegrating aid then needs to be used for effective disintegration of the tablet in turn lowering the probability of deposition of the disintegrating aid on the substrate being cleaned.
Thus according to a first aspect the present invention provides a tablet of compacted particulate detergent composition comprising non-soap surfactant and detergency builder, wherein the tablet or a discrete region thereof comprises; a tablet according to claim 1.
According to a second aspect the present invention provides a tablet of compacted particulate detergent composition according to claim 6
According to a third aspect of the present invention, there is provided a process for making the above tablets , which process comprises mixing compacted disintegrant co-granules with either water-soluble disintegration-promoting particles or with aluminosilicate builder material and one or more detergency enzymes, and with other constituents of the composition to produce a particulate composition, placing a quantity of the resultant particulate composition within a mould and compacting the composition within the mould to produce the tablet.

DETAILED DESCRIPTION

A tablet of the present invention may be either homogeneous or heterogeneous. In the present specification, the term "homogeneous" is used to mean a tablet produced by compaction of a single particulate composition, but does not imply that all the particles of that composition will be of identical composition. The term "heterogeneous" is used to mean a tablet consisting of a plurality of discrete regions, for example layers, inserts or coatings, each derived by compaction from a particulate composition. In a heterogeneous tablet according to the present invention, each discrete region of the tablet will preferably have a mass of at least 5 grams.
Unless otherwise stated, all references to percentages herein are to percentages by weight based upon the total weight of the tablet, or region thereof.

Disintegrant granules

A tablet according to the invention comprises non-soap surfactant, detergency builder and a disintegrant in the form of compacted co-granules, said disintegrant comprising a water-insoluble inorganic material in the form of a zeolite and a water-swellable agent with a specific water swelling capacity which in its anhydrous state comprises no more than 20% by weight of the combined weight of said inorganic material and said water-swellable agent of the granular disintegrant.
By "water-insoluble" as used herein, in relation to the zeolite material, is meant a zeolite with a solubility in water at 25°C of less than 5 grams per 100 grams of water, preferably less than 1 gram per 100 grams of water.
Preferred zeolites are zeolites P,A,X or Y or mixtures thereof, with Zeolite P being preferred. A type of Zeolite P, maximum aluminium zeolite P, known as zeolite MAP and so referred to herein (e.g. DOUCIL A24 ex Ineos Silicas UK) has been found to be especially effective.
It has been found that said disintegrants are more effective if the zeolites contain relatively little water. The preferred amount of water in the zeolite depends upon the type of zeolite used. For zeolites A and P, it is preferred that the amount of water is less than 21% by weight of the zeolite, more preferably less than 15% by weight, especially 8 to 13% by weight. Zeolite MAP, contains from about 9 to about 12% by weight of water and is especially useful according to the present invention.
For zeolite P we have found that good results are obtained from the partially hydrated material, e.g. zeolite MAP. As the water content in zeolite P is increased above this range (12% by weight for zeolite MAP), the effectiveness as a disintegrant decreases with increasing water content. Fully hydrated zeolite P (denoted "DOUCIL" A28 in the examples herein) has been found to be less effective as a disintegrant when compared to zeolite MAP.
Alkali metal aluminosilicates, especially zeolites, are used in detergent compositions as builders as further described hereinbelow. Where a composition according to the invention comprises a zeolite as a detergency builder, it is preferred that at least a part of the zeolite in the cleaning composition is employed as component in the formation of the disintegrant co-granules. As stated below, the builder, e.g. zeolite, typically comprises 10 to 60% by weight of the total composition. Preferably, the zeolite is used in the disintegrant co-granules and as part of the detergency builder in the composition, in that instance at least 1% by weight of the total weight of the composition comprises a zeolite constituent employed in the form of disintegrant co-granules.
The water-swellable agent preferably comprises, in its anhydrous state, no more than 15% by weight, preferably no more than 10% by weight, of the combined weight of said zeolite as inorganic material and said water-swellable agent of the granular co-disintegrant. Typically the water-swellable agent comprises, in its anhydrous state, no more than 8% by weight, e.g. 7.5% or less of the combined weight of said inorganic material and said agent. Generally, at least 1% of the combined weight of said inorganic material and said water-swellable agent in the granules comprises water-swellable agent. It is preferred that the water swellable agent comprises in its anhydrous state 1 to 15% by weight of the combined weight of said inorganic material and said water-swellable agent.
A relatively small amount of the water-swellable agent may, surprisingly, be used in the tabletted composition of the invention whilst still providing an acceptable effect. Usually the amount of water-swellable agent, based on the total weight of the tabletted composition, is less than 2% by weight, preferably less than 1% of the composition. Usually however, at least 0.2% by weight of the water-swellable agent is present in the tabletted composition.
Typically the water-swellable agent comprises polymer, often a wholly or partially cross-linked polymer, e.g. natural cellulose, cross-linked cellulose, (sodium) carboxymethyl cellulose, cross-linked sodium carboxymethyl cellulose, pre-gelatinised starch, cross-linked starch or cross-linked polyvinyl pyrrolidone. Currently preferred are Aquasorb A500 (ex Hercules) and Ac-Di-Sol and Nilyn XL90 (ex FMC Corporation, USA).
The water swellable agent in the disintegrant granule is preferably a cross-linked carboxymethyl cellulose, such as Aquasorb A500, Ac-Di-Sol and Nilyn as mentioned above. It is believed that these cross-linked carboxymethyl celluloses have particularly suitable levels of crosslinking and/or degree of substitution for use in the present invention.
Generally the compositions of the invention will contain from 1% to 20% by weight of the compacted disintegrant co-granules based on the total weight of the compositions, preferably 2 to 15%, more preferably 3 to 10%, e.g. 4 to 8% by weight. If the co-granules are included to aid dissolution only of the tablets rather than disintegration, then the amount of the granules in the tablets could be as low as 1% by weight.
The water-swellable agent preferably has an average primary particle size up to about 600um, but, conveniently, has an average primary particle size of no more than 200 um, preferably no more than 100um.
With the water insoluble inorganic material being a zeolite is it is preferred that the compacted disintegrant co-granules have a mean particle size in the range 700 to 1200 micrometers.
The water swellable agent has a water-swelling capacity of at least 5 cm³/gram, preferably at least 10cm³/gram and more preferably at least 20cm³/gram as determined in the test described hereinbelow.
The compacted disintegrant co-granules comprising the zeolite and the water-swellable agent may be prepared by any of the methods that will be known to those skilled in the art, e.g. by blending the dry ingredients in a mixer (such as a Pek mixer available from George Tweedy & Co of Preston - 281b S.A. Machine) and compacting on a roller compactor (Alexanderwerk WP50 - manufactured by Alexanderwerk AG, D 5630 Remschied 1, Germany).
A typical small-scale preparative method is now described in detail.
Inorganic material and the water-swellable agent are blended together in appropriate portions, in a Pek mixer for 30 minutes. A minimum of 2 kg of blended material so prepared is compacted by feeding into an Alexanderwerk roller compactor, fitted with a sintered block vacuum deaeration system. The roller pressure is selected according to the strength of granule desired, higher pressures leading to stronger granules. Generally, roller pressure is between 8 and 25 Mpa and a typical roller pressure is 10 Mpa. The compacted material from the compactor is fed into a granulator, which forms part of the machine, and forced through a mesh and the resulting granules are then screened to the desired particle size range, e.g. a mean average particle size of 250 to 1500 um, using standard laboratory sieves. Preferably the particles have a size range of 250 to 1200um. The granules, however produced, comprise an intimate mixture of particles of water insoluble inorganic material and water-swellable agent.

Surfactant Compounds

The compositions of this invention contain one or more non-soap surfactants. In a fabric washing composition, these preferably provide from 5 to 50% by weight of the composition of the tablet or region thereof, more preferably from 8 or 9% by weight of the composition up to 35% or 40% by weight. If the tablet is composed of more than one discrete region, then these preferred amounts of surfactant may apply to the tablet as a whole.
The organic surfactant may be present as a component in granulated particles in an amount between 10 and 70% by weight of the particles, more preferably 15 to 50% by weight based on the total weight of the granulated particles. All the surfactant in the composition may be contained within these particles. The surfactant may be anionic (soap or non-soap), cationic, zwitterionic, amphoteric, nonionic or a combination of these.
In a fabric washing tablet, anionic surfactant may be present in an amount from 0.5 to 50% by weight, preferably from 2% or 4% up to 30% or 35% or 40% by weight of the tablet or region thereof.
In a machine dishwashing composition, organic surfactant is likely to constitute from 0.5 to 8%, more likely from 0.5 to 5% of the composition of the tablet or region thereof and is likely to consist of nonionic surfactant, either alone or in a mixture with anionic surfactant.
Synthetic (i.e. non-soap) anionic surfactants are well known to those skilled in the art. Examples include alkyl benzene sulphonates, particularly sodium linear alkyl benzene sulphonates having an alkyl chain length of C₈-C₁₅; olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates.
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 rape seed oil.
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.
In certain forms 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 composition of the tablet or region thereof. Many nonionic surfactants are liquids. These may be absorbed onto particles of the composition prior to compaction into tablets.
Amphoteric surfactants may be used jointly with anionic or nonionic surfactants or both cationic surfactants may possibly be used. These frequently have a quaternised nitrogen atom in a polar head group and an attached hydrocarbon group of sufficient length to be hydrophobic.
The amount of amphoteric surfactant, if any, may possibly be from 3% to 20 or 30% by weight of the tablet or region of a tablet; the amount of cationic surfactant, if any, may possibly be from 1% to 10 or 20% by weight of the tablet or region of a tablet.

Detergency Builder

A composition which is compacted to form tablets or tablet regions typically contains a detergency builder which serves to remove or sequester calcium and/or magnesium ions in the water. Thus the builder acts as a water softener. In detergent tablets the amount of builder is likely to be from 5% to 80%, more usually 10% or 15% to 40%, 55% or 60% by weight of the tablet.
The detergency builder may be present in granulated particles in an amount of from 20 to 80% by weight, more preferably 20%, 25% or 30 to 60% by weight.
Detergency builders 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.
Alkali metal aluminosilicates are strongly favoured as environmentally acceptable detergency builders for fabric washing, and are preferred in this invention. Alkali metal (preferably sodium) aluminosilicates may be either crystalline or amorphous or mixtures thereof.
The less preferred category of water-soluble phosphorus-containing inorganic softeners includes the alkali-metal orthophosphates, metaphosphates, pyrophosphates and polyphosphates. Specific examples of inorganic phosphate detergency builders include sodium and potassium tripolyphosphates, orthophosphates and hexametaphosphates.
Non-phosphorus water-soluble detergency builders may be organic or inorganic. Inorganics that may be present include alkali metal (generally sodium) carbonate; while organics 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 have some function as water-softening agents and also inhibit unwanted deposition onto fabric from the wash liquor.
Where the tablet contains water soluble builder it is preferably present in an amount of from 10 to 80% by weight based on the total weight of the tablet or region thereof. Where the tablet contains water in-soluble builder it is preferably present in an amount of from 5 to 80% by weight based on the total weight of the tablet or region thereof.
Tablets comprising from 4 to 50% by weight of surfactant and from 5 to 80% by weight of builder are especially preferred for fabric washing tablets. Tablets comprising from 1 to 5% by weight of surfactant and from 50 to 98% of detergency builder are especially preferred for machine dishwashing tablets.
For the avoidance of doubt, where a tablet is heterogenous, the percentage ranges for the components referred to herein may apply to the overall composition of the tablet, as well as to at least one region of the tablet.

Water-Soluble Disintegration-Promoting Particles

According to the first aspect of the invention, the compositions of the invention, in either the whole tablet or in a region thereof, contain water-soluble disintegration promoting particles in addition to the disintegrant granules. These particles may also be present according to the second aspect of the invention. It is preferred that such disintegration-promoting particles make up from 2%, 3%, 5%, 8% or 10% up to 15%, 20%, 25% or 30% by weight of the composition of the tablet or region thereof. It is especially preferred that such disintegration-promoting particles make up from 5% to 25% by weight of the composition, based on the total weight of the composition.
Such soluble particles typically contain at least 40% (of their own weight) of one or more materials which is other than soap or organic surfactant and which has a solubility in deionised water of at least 50g/100g at 20°C. Preferably, at least a part of the water-soluble disintegration-promoting particles is added to a pregranulated portion of the composition which may contain organic surfactant and/or detergency builder used to produce the tablet. A proportion of such soluble material may also be included in granulated particles, in an amount of preferably 1 to 25% by weight, more preferably 3 or 5% to 10% or 15% by weight of these granulated particles.
More preferably this water-soluble material is selected from compounds containing at least 40% (by weight of the particles) of one or more materials selected from the group consisting of; compounds with a water-solubility exceeding 50 grams/100 grams in water at 20°C; or sodium tripolyphosphate containing at least 50% of its own weight of the phase I anhydrous form; or 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.
As will be explained further below, these disintegration-promoting particles can also contain other forms of tripolyphosphate or other salts within the balance of their composition.
If the material in such water-soluble disintegration-promoting particles can function as a detergency builder, (as is the case with sodium tripolyphosphate) then of course it contributes to the total quantity of detergency builder in the tablet composition.
A solubility of at least 50 g/100g of deionised 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 to form a saturated solution in 100 grams of deionised water at 20°C:-

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

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 material is incorporated as particles of the material in a substantially pure form (i.e. each such particle contains 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. Preferred water-soluble materials having a solubility exceeding 50 grams/100 grams of deionised water at 20°C are sodium citrate dihydrate, urea, and sodium acetate. The sodium acetate may be in a partially or fully hydrated form (trihydrate). Sodium acetate trihydrate is especially preferred.
It may be preferred that the highly water-soluble material is a salt which dissolves in water in an ionised form. As such a salt dissolves it leads to a transient local increase in ionic strength which can assist disintegration of the tablet by preventing nonionic surfactant from swelling and inhibiting dissolution of other materials.
Specifically, tablets of this invention may contain water-soluble salt, with a solubility exceeding 50g/100g of deionised water at 20°C, both as a small percentage within the said granulated particles and as separate particles which are mixed with them.
Within granulated particles which may contain surfactant and/or builder, such highly water soluble salt may be present in an amount of from 0 to 30% by weight of those particles, preferably of from 3 to 10% or 15% thereof, while the materials added to those particles before tabletting may be such highly soluble salts in an amount of from 2 or 5% up to 15% by weight of the whole tablet formulation.
Another possibility, which is less preferred, is that the said particles which promote disintegration are particles which contain sodium tripolyphosphate with more than 50% (by weight of the particles) of the anhydrous phase I form, and, which is partially hydrated so as to contain water of hydration in an amount which is at least 1% by weight of the sodium tripolyphosphate.
Sodium tripolyphosphate is very well known as a sequestering builder in detergent compositions. It exists in a hydrated form and two crystalline anhydrous forms. These are the normal crystalline anhydrous form, known as phase II which is the low temperature form, and phase I which is stable at high temperature.
The remainder of the tablet composition used to form the tablet or region thereof may include additional sodium tripolyphosphate. This may be in any form, including sodium tripolyphosphate with a high content of the anhydrous phase II form. Suitable material is commercially available. Suppliers include Rhone-Poulenc, France and Rhodia, UK.
Some countries require that phosphate is not used. For such countries, a zero-phosphate tablet in accordance with this invention may utilise a suitable amount, e.g. 15% by weight or more of disintegration-promoting material with solubility of at least 50gm/100gm at 20°C. Other countries permit the use, or at least some limited use, of phosphates, making it possible to use some sodium tripolyphosphate.

Optional water-soluble organic polymer

Tablets of the present invention may include a water-soluble organic polymer which is solid at 25°C to act as a binder for the particulate composition when compacted. This may be included in granulated particles containing organic surfactant and/or detergency builder.

Optional bleach system

Tabletted 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 of the tablet or region thereof.

Enzymes

Tablets according to the second aspect of the invention comprise one or more detergency enzymes. Preferably the enzyme is selected from amylase, protease, cellulase, lipase and mixtures thereof. The aforementioned enzymes are designed to remove a variety of soils and stains from fabrics. Detergent tablets according to the first aspect of the invention may also comprise one or more detergency enzymes.

Optional other ingredients

The tablets of the invention may also contain a fluorescer, an antifoam material in an amount up to 5% by weight of the composition of the tablet or region thereof, an alkali metal silicate, particularly sodium
ortho-, meta- or disilicate in providing protection against the corrosion of metal parts in washing machines.

Bulk density of non-compacted detergent powder & granulation

While the starting particulate composition from which the tablets are produced may in principle have any bulk density, the present invention may be especially relevant to tablets of detergent composition 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, 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 possibly at least 600 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-A-340 013 (Unilever ), EP-A-352 135 (Unilever ), and EP-A-425 277 (Unilever ), or by the continuous granulation/densification processes described and claimed in EP-A-367 339 (Unilever ) and EP-A-390 251 (Unilever ), are inherently suitable for use in the present invention.
Another particularly suitable process for the preparation of a high-bulk density detergent powder is described in WO-A-98/11193 (Unilever ). In this document, a feedstock of the starting acid for production of the anionic surfactant is partially neutralised, for example by sodium hydroxide, before being fed into a high-speed mixer densifier (e.g. Lodige CB 30 Recycler) where the partially neutralised acid feedstock is completely neutralised, whilst being mixed with the majority of other components of the detergent base powder granule. This powder can be further densified by treating in a moderate speed mixer (e.g. Lodige KM 300 mixer), before which stage further detergency builder may be added. The water-soluble polymer material is preferably added before the further densification step, although it may be added in the first mixer. The water-soluble polymer material may be heated to a temperature considerably above its melting point to obtain a free-flowing liquid. The resulting powder can be cooled and dried using a fluid bed, after which any desired particle size control can be exercised.
Any separate particles containing further components of the finished formulation can be mixed with the base powder prior to compaction.

Particle size control

Particle sizes can be controlled in the manufacturing process of any particles included in the composition. Oversize particles are usually removed by sieving (for example by a Mogensen screen) at the end of the production process, followed by milling and recycling of the removed oversize fraction. Undersize particles can also be removed by sieving, or if the manufacturing process employs a fluidised bed then undersized particles may be entrained in the air stream and subsequently recovered from it for recycling to the granulation stage.
It is preferred that the average particle size of granulated particles forming the particulate composition from which,the tablet is formed is between 400 and 1100 micrometers, preferably between 500 and 1000 micrometers. Preferably no more than 5% of these particles are smaller than 200 micrometers while no more than 5% are larger than 1400 micrometers.
Materials which are mixed with the granulated particles may also comply with these requirements concerning particle size. These materials (post-added) typically comprise from 5% - 60% by weight of the total weight of the final composition, more usually 35 to 55% by weight.

Tabletting

Tabletting entails compaction of a particulate composition. A variety of tabletting 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. Tabletting 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 tabletting at a temperature which is above ambient, the particulate composition is preferably supplied to the tabletting machinery at an elevated temperature. This will of course supply heat to the tabletting machinery, but the machinery may be heated in some other way also. 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, preferably from 15 to 60 grams, 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 for fabric washing preferably lies in a range from 1040 or 1050g/litre preferably at least 1100g/litre up to 1400g/litre. The tablet density may well lie in a range up to no more than 1350 or even 1250g/litre. The overall density of a tablet of some other cleaning composition, such as a tablet for machine dishwashing or as a bleaching additive, may range up to 1700g/litre and will often lie in a range from 1300 to 1550g/litre.
The detergent tablet may be made by a process which comprises mixing the compacted disintegrant co-granules with either the water-soluble disintegration-promoting particles or with the aluminosilicate builder material and one or more detergency enzymes, and with the other constituents of the composition, placing a quantity of the resultant particulate composition within a mould and compacting the composition within the mould to produce the tablet.

Tablet testing - disintegration

The speed of disintegration of the tablets in the examples was measured by means of a test procedure under static conditions in which a pre-weighed tablet was placed on a metal grid with 1 X 1 cm mazes and the tablet and grid was then immersed in a suitable amount of 15° FH (French Hardness) tap water at 10°C or 20°C so that the tablet when immersed is covered by 2cm of water. After 60 seconds the metal grid is carefully taken out of the water and the wet tablet residue is weighed. If the tablet had fully disintegrated in this time then the time taken for 100% disintegration is recorded.
It is especially preferred that the tablets exhibit 50% or more disintegration in the above test, more preferably 60% or more, most preferably 70% or more.

Tablet Strength

The strength of the tablets, in their dry state as made on the compaction press, can be determined according to their diametrical fracture stress DFS, which is calculated from the equation: $DFS = \frac{2 F_{\max}}{πDt}$

where DFS is the diametrical fracture stress in Pascals, F_max is the applied load in Newtons to cause fracture, D is the tablet diameter in metres and t is the tablet thickness in metres. The test is carried out using an Instron type universal testing instrument to apply compressive force on a tablet diameter (i.e. perpendicular to the axis of a cylindrical tablet). It is preferred that tablets have a DFS of at least 20 kPa more preferably at least 25 kPa, such as 30 kPa or above.
It is intended that the tablets, when used as fabric washing tablets in an automatic washing machine, may be added either to the powder dispensing draw, or, directly in to the washing drum. This may occur either manually or automatically.

Determination of the water-swelling capacity

To demonstrate the water-swelling capacity of the water - swellable agent, 19.6 grams of the agent or carrier was blended with 0.4 grams of ultramarine pigment and compressed into a tablet using a laboratory tablet press at about 250 MPa to give a tablet of 32 mm diameter. This was crushed and sieved to give granules of particle size 500 - 1000 um. A glass tube, 33 mm in internal diameter and about 30 cm long with a sintered porous glass disk (porosity ₁) fitted at one end was immersed upright, with said one end lowermost, in a large beaker of water (at 25°C) so that the water level rose to about 14 cm above the sintered glass. 1 gram of the granules was added to the tube and allowed to settle on the sintered glass disc. With this arrangement water has access to the granules from both above and below. The granules immediately began to swell, forming a jelly-like mass. The ultramarine pigment imparted a blue colour to the mass making it easy to see the end and to record its height. The height of the swelling mass was recorded at intervals and showed an initial rapid rise followed by a level off after about 20-30 minutes. From the diameter of the tube, the volume of the swollen mass can be calculated. The result was expressed as cm³/g of the water swellable agent after 20 minutes.
The detergent/cleaning tablets of the invention are suitable for use in what is known in the art as 'homecare' applications. That is, detergent tablets which are suitable for use in cleaning and maintainance operations typically carried out around the home. It does not include operations carried out directly on a human or animal body which are known as 'personal care' applications. Examples of 'homecare' detergent tablets include; laundry tablets, (machine) dishwashing tablets, hard-surface cleaning tablets, toilet-cleaning tablets, bleaching tablets, water-softening tablets etc.

EXAMPLES

The invention will be further described by reference to the following examples. Further examples within the scope of the present invention will be apparent to the person skilled in the art.

Preparation of a stock granulated powder

Two stock granular detergent powders were made having the compositions in table 1 by granulating the ingredients above the entry "post-dosed ingredients" under high shear followed by densification under reduced shear and then adding to this granular component the post dosed ingredients as described hereinbefore under the heading "Granulation Process".

Table 1; Stock powder formulations

	Stock 1	Stock 2
Sodium linear alkylbenzene sulphonate	14.25	11.99
C_13-15 fatty alcohol 7EO, branched.	4.28	3.43
C_13-15 fatty alcohol 3EO, branched	-	1.84
Soap	0.75	0.91
Zeolite*¹ (anhydrous)	27.62	26.8
Sodium acetate trihydrate/zeolite blend (99:1 wt mixture)	3.72	3.43
Sodium carbonate	4.00	3.98
Sodium Carboxymethyl cellulose (69%wt active)	0.58	0.54
Salts, moisture and NDOM*²	5.08	4.82
POST-DOSED INGREDIENTS;
Anti-foam granules	2.74	2.25
Fluorescer adjunct	2.74	2.11
SOKALAN HP23 adjunct*³	1.37	1.41
Sodium citrate dihydrate	-	4.93
tetraacetylethylene diamine (TAPED) granules, (83% active)	5.48	5.28
Sodium Percarbonate (coated)*⁴	20.55	19.71
Sodium silicate granules (80% active )	4.53	4.22
EDTMP granulate (DEQUEST 2047)*⁵	1.01	1.01
EHDP granulate (DEQUEST 2016)*⁶	0.68	0.7
Perfume	0.62	0.63
TOTAL	100% by weight	100% by weight

*¹ 'DOUCIL A24', a maximum aluminium zeolite P (MAP) ex Ineos Silicas, UK.
*² NDOM is non detergent organic matter
*³ SOKALAN HP23 is a grafted co-polymer of polyethylene oxide and polyvinylacetate ex BASF, Germany.
*⁴ Coated percarbonate ex Interox, UK.
*⁵ DEQUEST 2047 is ethylene diamine tetra methylene phosphonate ex Monsanto.
*⁶ DEQUEST 2016 is ethylene hydroxy diphosphonate ex Monsanto.
*⁷ SOKALAN CP5 is a co-polymer of acrylic acid and maleic acid ex BASF, Germany.

Disintegrant Granules A to G

Seven disintegrant granules were prepared by the typical preparative method described under the heading "Disintegrant granules". The disintegrant granules used either a zeolite or silica as the water-insoluble inorganic material. The water-swellable agent was chosen from one of four types of water-swellable agents. The granules had the compositions given in table 2 and were sieved to collect the fraction having a particle size of 250 to 700um or 700 to 1200 um. Unless otherwise stated the particle size is or 700 to 1200 um. The amounts given in Table 2 are the percentages of each ingredient in the disintegrant granule and add up to 100% by weight based on the total weight of the granule.

Table 2; Disintegrant granule compositions

	A	B	C	D	E	F	G
Inorganic material;
Zeolite P*¹	92.5		92.5	92.5	92.5
Zeolite A4						92.5
Zeolite P*⁸							92.5
Silica		92.5
Water swellable agent;
Aquasorb A500*⁹	7.5	7.5
Ac-Di-Sol*¹⁰			7.5
Arbocel FT40*¹¹				7.5		7.5	7.5
National Starch 78-1551*¹²					7.5

*⁸ Fully hydrated "DOUCIL A24" zeolite ex Crosfield.
*⁹ Cross-linked CMC ex Hercules.
*¹⁰ Cross-linked CMC ex FMC Corporation, USA.
*¹¹ Raw Cellulose Fibre of particle size about 200 um ex Rettenmaier, Germany.
*¹² Pre-gelatinised Corn Starch ex National Starch and Chemical Company.

Comparative examples C1 and C2.

The 'stock 1' composition of table 1 was mixed with additional sodium acetate trihydrate/zeolite blend (99:1 parts by weight) as shown in table 3 to produce comparative examples C1 and C2. Comparative example C1 contains no disintegrant granule. Comparative example C2 also contains no disintegrant granule but contains Aquasorb A500 cross-linked CMC added as a separate ingredient as well as some additional zeolite powder. The amounts in Table 3 add up to 100% by weight. Table 3; comparative examples C1 and C2.

C1 C2

Stock 1 composition 78.0 74.0

Sodium acetate/zeolite blend 22.0 21.0

Aquasorb A500*⁹ - 0.35

Zeolite*¹ - 4.65
40g portions of each comparative composition were made into cylindrical tablets of 44.5 mm diameter and height 18-22 mm using a Graseby Specac laboratory tabletting machine. The compaction pressure used for each tablet was adjusted so that the tablets were all compacted to the same diametrical fracture stress of 30 kPa. The strength of the tablets, in their dry state as made on the press, was determined as their diametrical fracture stress DFS by the method detailed in the description of the invention above.

Examples 1 to 11

The 'stock 1' composition of table 1 was mixed with varying amounts of disintegrant granule and in some examples additional sodium acetate trihydrate/zeolite blend (99:1 parts by weight) as shown in table 4 to produce examples 1 to 11 which are examples according to the invention. The amounts in Table 4 add up to 100% by weight. A to E below refer to the disintegrant granule for which details are given above.

Table 4; preparation of examples 1 to 11.

	1	2	3	4	5	6	7	8	9	10	11
Stock 1	73	73	95	95	73	73	95	95	75	75	75
A,250-700um	5	-	5	-	-	-	-	-	-	-	-
A,700-1200um	-	5	-	5	-	-	-	-	-	-	-
B,250-700um	-	-	-	-	5	-	5	-	-	-	-
B,700-1200um	-	-	-	-	-	5	-	5	-	-	-
C	-	-	-	-	-	-	-	-	4	-	-
D	-	-	-	-	-	-	-	-	-	4	-
E	-	-	-	-	-	-	-	-	-	-	4
Na acetate /zeolite blend	22	22	-	-	22	22	-	-	21	21	21

These compositions were compacted on a Graseby Laboratory Tablet Press as detailed above for comparative examples C1 and C2 above.

Disintegration results of comparative examples C1 and C2 and Examples 1 to 11.

The speed of disintegration of the tablets was measured under static conditions as described above under the heading "Tablet testing - disintegration". The disintegration results are given in table 5.
Table 5; disintegration results of Examples 1-11 and comparative examples C1 and C2.

Example % disintegration in 60 seconds at 20°C

C1 Absorbs water; 20% wt gain.

C2 17%

1 77%

2 100%

3 11%

4 32%

5 57%

6 38%

7 57%

8 49%

9 100%

10 82%

11 70%
The above results show that with the disintegrant granules of the invention good disintegration of a detergent tablet can be obtained in an acceptable time. In the absence of post-added acetate, the disintegrant granules comprising silica as the inorganic material are more effective than those comprising zeolite. Example 3 shows improved disintegration over comparative example C1 (which comprises no disintegrant granule and no acetate). This is observed for both the smaller and larger disintegrant granule particle sizes (compare examples 3 & 7 and 4 & 8). By increasing the particle size of the disintegrant granule, the disintegration result can be improved (compare examples 3 and 4). However, in the presence of acetate the disintegrant granules comprising zeolite as the inorganic material are more effective than those comprising silica. This is observed for both the smaller and larger disintegrant granule particle sizes (compare examples 1 & 5 and 2 & 6). Comparative example 2 shows that acetate, in the absence of the disintegrant granule alone is not totally effective.
Examples 9 to 11 show that the following water-swellable polymers are effective as part of the disintegrant granule in the descending order; Ac-Di-Sol > Arbocel FT40 > National Starch 78-1551. This demonstrates that the cross-linked CMC disintegrants are more effective than the pre-gelatinised starch. Comparative example C1 demonstrates that in the absence of either a swellable polymer or the disintegrant granule the tablet does not disintegrate but instead takes in water. Comparative example C2 demonstrates that limited disintegration is achieved when the inorganic carrier and swellable polymer are added in a non-granulated form.

Comparative example C3.

The 'stock 2' composition of table 1 was mixed with additional sodium acetate trihydrate/zeolite blend (99:1 parts by weight) as shown in table 6 to produce comparative example C3. Table 6; comparative example C3.

Stock 2 composition 76.6

Sodium acetate/zeolite blend 23.4
40g portions of the C3 composition were made into cylindrical tablets as detailed above for comparative examples C1 and C2.

Examples 12 to 19

The 'stock 2' composition of table 1 was mixed with varying amounts of disintegrant granule and in some examples additional sodium acetate trihydrate/zeolite blend (99:1 parts by weight) and/or PEG 1500 powder as shown in table 7 to produce examples 12 to 19 which are examples according to the invention. The amounts in Table 7 add up to 100% by weight. C to G in the table refers to the disintegrant granule.

Table 7; preparation of examples 12 to 19.

	12	13	14	15	16	17	18	19
Stock 2	75	75	75	71.6	71.6	83	83	83
C	-	-	-	5	-	15	-	-
D	4	-	-	-	5	-	15	-
E	-	-	-	-	-	-	-	15
F	-	-	4	-	-	-	-	-
G	-	4	-	-	-	-	-	-
PEG 1500 powder	-	-	-	2	2	2	2	2
Na acetate /zeolite blend	21	21	21	21.4	21.4	-	-	-

Disintegration results of comparative example C3 and Examples 12 to 19.

The speed of disintegration of the tablets was measured under static conditions as described under the heading "Tablet testing - disintegration". The disintegration results are given in table 8. Table 8; disintegration results of Examples 12-19 and comparative example C3.

Example % disintegration in 60 seconds at 20°C

C3 Absorbs water; 19% wt gain.

12 100%

13 9%

14 14%

15 89%

16 93%

17 72%

18 100%

19 87%
When using a zeolite carrier in the disintegrant granule, Zeolite MAP has been found to work particularly well (see examples 12 and 15-19). Example 13 demonstrates that fully hydrating the zeolite*¹ (as used in disintegrant granules A and C-E) results in lower disintegration values. Example 14 demonstrates that the zeolite known as Zeolite A4 is also not as effective as the zeolite*¹ as a carrier. Examples 17 to 19 show good results for high levels of the disintegrant granule in the absence of post-added acetate. Comparative example C3 demonstrates that disintegration is not achieved in the absence of the disintegrant granule.

Examples 20 to 22

Examples 20 to 22 were prepared by preparing a base powder by granulation as described above for the stock compositions to obtain a composition having the overall compositions given in table 9.

Table 9; Ingredient	% by weight
	20	21	22
Sodium linear alkyl benzene sulphonate	9.01	8.84	8.67
C_13-15 fatty alcohol 7EO, branched.	2.58	2.53	2.48
C_13-15 fatty alcohol 3EO, branched	1.38	1.35	1.33
Soap	0.68	0.67	0.66
Zeolite*¹ (anhydrous)	20.15	19.75	19.37
Sodium acetate trihydrate/zeolite blend (99:1 wt mixture)	2.58	2.53	2.48
Sodium carbonate	2.99	2.93	2.88
Sodium carboxymethyl cellulose (69%wt active)	0.40	0.39	0.39
Salts, moisture and NDOM*²	3.63	3.55	3.49
Post-dosed ingredients;
Polyethylene glycol 1500 powder	-	1.96	3.85
Disintegrant granule A	4.00	3.92	3.85
Anti-foam granules	1.74	1.71	1.67
Fluorescer adjunct	1.50	1.47	1.44
SOKALAN HP23 adjunct*³	1.00	0.98	0.96
Poly vinyl pyrrolidone	0.15	0-15	0.14
Sodium citrate dihydrate	3.50	3.43	3.37
Sodium acetate trihydrate/zeolite blend (99:1 wt mixture)	21.15	20.74	20.34
tetraacetylethylene diamine (TAED) granules, (83% active)	4.00	3.92	3.85
Sodium percarbonate (coated)*⁴	14.00	13.73	13.46
Sodium silicate granules (80% active )	3.00	2.94	2.88
EDTMP granulate (DEQUEST 2047)*⁵	0.72	0.71	0.69
EHDP granulate (DEQUEST 2016)*⁶	0.50	0.49	0.48
Savinase 12T	0.80	0.78	0.77
Lipolase 100T	0.10	0.10	0.10
Perfume	0.45	0.44	0.43
TOTAL	100% by weight	100% by weight	100% by weight

These compositions were compacted on a Graseby Laboratory Tablet Press as detailed above for comparative examples C1 and C2 above.
The speed of disintegration of the tablets was measured under static conditions as described under the heading "Tablet testing - disintegration". The disintegration results are given in table 10. Table 10; disintegration results of Examples 20- 22.

Example % disintegration in 60 seconds at 20°C

20 51%

21 48%

22 31%
The addition of increasing levels of PEG 1500 powder is seen to have an increasingly negative effect on the tablet disintegration properties in these tablets.

Claims

A tablet of compacted particulate detergent composition comprising non-soap surfactant and detergency builder, wherein the tablet or a discrete region thereof comprises;
a) from 1 to 20% by weight based on the total weight of the tablet or region thereof of disintegrant granules comprising a water insoluble inorganic material and a water swellable agent which, in its anhydrous state, comprises no more than 10% by weight of the combined weight of the inorganic material and the water swellable agent, and

b) water-soluble disintegration-promoting particles containing at least 40%, by weight of the particles, of one or more materials selected from the group consisting of;
i) compounds with water-solubility exceeding 50 grams per 100 grams water at 20°C, and

ii) sodium tripolyphosphate containing at least 50% of its own weight of the phase I anhydrous form, and

iii) 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.
A tablet according to claim 1, wherein the compounds with water-solubility exceeding 50 grams per 100 grams water comprise sodium acetate, sodium citrate dihydrate or urea.
A tablet according to claim 2 wherein the compounds with water-solubility exceeding 50 grams per 100 grams water comprise sodium acetate trihydrate.
A tablet according to any one of claims 1 to 3 wherein the water-soluble disintegration-promoting particles are present in an amount of from of from 2% to 25% by weight based on the total weight of the composition.
A tablet according to any one of the preceding claims wherein at least a part of the water-soluble disintegration-promoting particles is added to a pregranulated portion of the composition used to produce the tablet.
A tablet of compacted particulate detergent composition comprising non-soap surfactant and detergency builder, wherein the tablet or a discrete region thereof comprises;
a) from 1 to 20% by weight based on the total weight of the tablet or region thereof of disintegrant granules comprising a water insoluble inorganic material and a water swellable agent which, in its anhydrous state, comprises no more than 10% by weight of the combined weight of the inorganic material and the water swellable agent, and

b) 10 to 60% by weight of an aluminosilicate builder, based on the total weight of the tablet or discrete region thereof, and one or more detergency enzymes.
A tablet according to claim 6 wherein the aluminosilicate builder comprises maximum aluminium zeolite P or zeolite A.
A tablet according to any one of the preceding claims wherein the water insoluble inorganic material in the disintegrant granule comprises an aluminosilicate or silica.
A tablet according to claim 8 wherein the aluminosilicate comprises a zeolite.
A tablet according to claim 9 wherein the zeolite comprises zeolite P.
A tablet according to claim 10 wherein the zeolite comprises a maximum aluminium zeolite P.
A tablet according to any one of the preceding claims wherein the water swellable agent in the disintegrant granule is selected from the group consisting of cellulose, cross-linked cellulose, carboxy methyl cellulose, sodium carboxymethyl cellulose, crosslinked sodium carboxymethyl cellulose, pre-gelatinised starch, cross-linked starch and cross-linked polyvinyl pyrrolidone.
A tablet according to claim 12 wherein the water swellable agent comprises a cross-linked sodium carboxymethyl cellulose.
A tablet according to any one of the preceding claims wherein the water swellable agent comprises, in its anhydrous state, 1 to 8% by weight of the combined weight of the inorganic material and the water swellable agent of the granular disintegrant.
A tablet according to any one of the preceding claims wherein the water insoluble inorganic material in the disintegrant granule comprises a zeolite and the disintegrant granules have a mean particle size in the range of from 700 to 1200 micrometers.
A tablet according to anyone of claims 1 to 8 or 12 to 14. wherein the water insoluble inorganic material in the disintegrant granule comprises silica and the disintegrant granules have a mean particle size in the range 250 to 700 micrometers.
A tablet according to any one of the preceding claims wherein the water swellable agent in the disintegrant granule is present in an amount of less than 2% by weight based on the total weight of the tablet or region thereof.
A tablet according to any one of the preceding claims wherein the water swellable agent has an average primary particle size of no more than 200 um.
A process for making a tablet of compacted particulate composition according to either of claims 1or 6 which process comprises mixing disintegrant granules with either water-soluble disintegration-promoting particles or with aluminosilicate builder material and one or more detergency enzymes, and with other constituents of the composition to produce a particulate composition, placing a quantity of the resultant particulate composition within a mould and compacting the composition within the mould to produce the tablet.