GB2342098A - Detergent composition - Google Patents

Abstract

A detergent tablet, or a region of such a tablet, is a compacted particulate detergent composition containing surfactant and sodium tripolyphosphate which is rich in the Phase I form and is slightly hydrated. Sodium citrate dihydrate has been found superior to other possible salts as a further ingredient.

Description

2342098 DETERGENT COMPOSITION This invention relates to detergent

compositions in the form of tablets for fabric washing. It is known to make such tablets by compressing or compacting a quantity of detergent composition in particulate form.

It is desirable that tablets should have adequate mechanical strength when dry, before use, yet disintegrate and disperse/dissolve quickly when added to wash water.

It has not proved simple to achieve both properties simultaneously. As more pressure is used when a tablet is compacted, so the tablet density and strength rise, but the speed of disintegration/dissolution when the tablet comes into contact with wash water goes down.

A tablet may be either homogeneous or heterogeneous. In the present patent 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 necessarily 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.

Our European published application EP-A-839906 describes tablets of a compacted, particulate detergent composition 2 intended for fabric washing in which the tablet comprises particles containing sodium tripolyphosphate with a substantial content of the phase I form, and this tripolyphosphate is partially hydrated so as to contain water of hydration in an amount between 1% and 5% by weight of the sodium tri-polyphosphate in those particles.

It is demonstrated by examples in the patent application that tablets incorporating particles with a substantial content of the Phase I form of sodium tri-polyphosphate and io with some partial hydration of the tripolyphosphate disintegrate and dissolve in use much more quickly than comparative tablets using sodium tripolyphosphate with a higher content of the Phase!I form. Consequently, it is possible to achieve tablets which disintegrate rapidly at the time of use.

Typically these tablets will contain base powder particles which incorporate organic detergent -active surfactant together w---th some tripolyphosphate detergency builder, separate particles containing sodium tripolyphosphate which is rich in the Phase I form and also partially hydrated, and thirdly particles of other ingredients.

Such tablets have been marketed commercially. For use one or two tablets are placed in a net bag, closed with a drawstring. The bag containing tablets is placed in the washing machine, with fabrics t--o be washed.

3 In the case of tablets exemplified in the prior document, and also tablets containing such tripolyphosphate which have been marketed commercially, a substantial proportion of the other ingredients is constituted by peroxygen 5 bleach.

We have now found it desirable to incorporate particles of another inorganic salt, in addition to the particles of sodium tripolyphosphate. One circumstance in which we have found this to be desirable is for tablets which are bleach free, although it might also be done when bleach is present.

In our published European application EP-A-711827, it is demonstrated that the speed of disintegration of detergent tablets containing insoluble aluminosilicate builder can be increased by incorporating sodium citrate dihydrate into the formulation.

However, in our more recent published application EP-A838519, we have demonstrated that the rapid dissolution of water softening tablets containing aluminosilicate can be promoted by the use of sodium acetate trihydrate. In examples where the detergent composition included particles containing zeolite mixed with detergent surfactant, sodium acetate trihydrate was demonstrated to be efficacious in bringing about rapid disintegration and was more effective than sodium citrate dihydrate.

4 When a tablet already contains an effective system to cause disintegration, it is not predictable that further improvements can be obtained. From the above documents it might be supposed that in a detergent tablet formed from a 5 composition containing surfactant and particles of sodium tripolyphosphate rich in the Phase I form in accordance with the above EP-A-839906, in sufficient amount to achieve rapid decomposition of the tablet at the time of use, if any further enhancement of the speed of disintegration could be achieved by incorporating additional material, sodium acetate trihydrate would be the evident optimum candidate. Unexpectedly, we have found that in this context, sodium citrate dihydrate -.s more efficacious than sodium acetate trihydrate.

is According to a first aspect of the present invention, there is provided a detergent tablet wherein the tablet or a region thereof is a compacted particulate detergent composition containing (i) detergent surfactant, (ii) particles which contain sodium tripolyphosphate with a content of the Phase I form which is more than 40% by weight of the sodium tripoLyphosphate in the said particles and wherein the sodium tripolyphosphate in the said particles contains water of hydration in an amount between 1% and 5% by weight of that sodium tripoly-phosphate, and (iii) particles of other ingredients characterised in that said other ingredients include particles of sodium. citrate dihydrate.

Preferably the sodium tripolyphosphate in the said particles has a content of the Phase I form which is at least 50% by weight of the sodium tripolyphosphate in the said particles. It is also preferred that the amount of water of hydration in the sodium tripolyphosphate particles lies in a range from 2% to 4% by weight of the sodium tripoly-phosphate in those particles.

Preferably the quantity of detergent surfactant is from 5 to 40% by weight of the overall composition, more preferably is at least 8% or 10% by weight. It is likely that the amount will not exceed 30% by weight, perhaps not over 20 or 25% by weight. This detergent may be a mixture of surfactants and it likely to include both anionic and nonionic surfactants.

Preferably the surfactant is provided as particles which include some other ingredients, such as inorganic salts.

The quantity of sodium tripolyphosphate of the specified characteristics, that is to say with at least 40% by weight of Phase I form and partial hydration in an amount between 1% and 5% by weight of this tripolyphosphate, is preferably at least 25% of the overall composition, more preferably at least 30% of the overall composition of the tablet or region thereof. While amounts up to at least 55% by weight of the composition can be contemplated, it is likely that, the amount will not exceed 50% by weight of the composition and 6 preferably not more than 45% by weight of the composition.

The amount of sodium citrate dihvdrate is preferably at least 3% by weight of the composition and may well be at least 5% or at least 7% by weight of the composition but is unlikely to exceed 20% by weight. The total quantity of specified sodium tripolyphosphate and sodium citrate dihydrate preferably lies in a range from 35 to 60% by weight of the composition, more preferably at least 40% by weight. The total of these two materials is preferably an amount from 40% up to 55% or 60% by weight of the tablet or region.

Features of this invention, suitable materials and further preferences will now be described in more detail.

Sodium Tri-polymhosiDhate with High Phase I Content As diSCUSSE!d in EP-A-839906, sodium tripolyphosphate can be converted to the phase I form by heating to above the transition temperature at which phase II anhydrous sodium polyphosphate is transformed into the phase I form. A process for the manufacture of particles containing a high proportion of the phase I form of sodium tri-polyphos-phate by spray drying below 4200C is given in US-A-4536377.

Suitable material is commercially available. Suppliers include RhonePoulenc, Courbevoie, France and Albright & 7 Wilson, Warley, West Midlands, UK. The sodium tripolyphosphate should be partially hydrated, but the phase I anhydrous form should also be present. Thus, the sodium tripolyphosphate in the particles may incorporate from 0.5% 5 up to, at least, 5% (by weight of the sodium tripolyphosphate in these particles) of water of hydration. The extent of hydration is desirably from 1% to 4 or 5% by weight.

The sodium tripolyphosphate in these particles is preferably hydrated by a process which leads to a homogeneous distribution of the water of hydration within the tripolyphosphate.

This can be accomplished by exposing anhydrous sodium tripolyphosphate to steam or moist air. The particles preferably consist solely of sodium tripolyphosphate with a high content of the phase I form.

The particles preferably contain sodium tripolyphosphate in a porous form so as to have high surface area. This can be achieved by spray drying the tripolyphosphate as a mixture with a blowing agent, that is a compound such as ammonium carbonate which decomposes to yield a gas during the course of the spray drying. This gives the dried material a porous structure, with higher surface area than hollow beads of tripolyphos-phate obtained without blowing agent.

8 The particles which contain or consist of sodium tri-polyphosphate preferably have a small mean particle size, such as not over 300,um, better not over 250,um. Small -oarticle size can if necessary be achieved by grinding.

Uniform prehydration, high phase I content, porosity and small particle size all promote rapid hydration when the tripolyphosphate comes into contact with water. A standard test for the rapidity of hydration is the Olten test. It is desirable that in such a test the tripolyphosphate reaches 90% of the final value (ie 90% of complete hydration when exposed to water at 80'C) within 60 seconds. "Rhodiaphos HPA 3.5" is a grade of sodium tripoly-phosphate from Rhone-Poulenc which has been found to be particularly suitable. It consists of porous particles of small particle size (mean size below 250 um) with 70% phase I and prehydrated with 3.5% water of hydration.

Preferably the said particles containing sodium tripolyphosphate with more than 40% of phase I material provide sodium tripolyphosphate, including the phase I tripolyphosphate, in a quantity which is from 12% up to 30% or 35% by weight of the tablet or region thereof. A quantity of at least 25% has been found useful in some tablezs.

The remainder of the tablet composition may include additional sodium tripoly-phosphate. This may be in any form, 9 including anhydrous sodium tripolyphosphate with a high content of the phase II form, hydrated sodium tripolyphosphate or some combination of the two.

The total quantity of sodium tripolyphosphate, in all forms, present in the tablet composition will generally lie in a range up to 60% by weight of the tablet. Therefore it will be appreciated that the overall quantity of sodium tripolyphosphate may be provided at least partially by other material in addition to the said particles.

Surfactants Tablet compositions of this invention contain one or more organic surfactants, frequently referred to as detergentactive compounds. Preferably these provide at least 5% by weight of the composition of the overall tablet or of a region thereof, more preferably at least 9% or 11% by weight of the composition. organic detergent-active compounds may be anionic (soap or non-soap), cationic, zwitterionic, amphoteric, nonionic or a combination of these, especially combinations of non-soap anionic, nonionic and possibly soap.

Anionic detergent-active compounds may be present in an amount from 0.5% to 40% by weight, preferably from 4% or 6% up to 30% or 40% by weight of the composition of the tablet or of a tablet region.

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 CS-Cls; olefin sulphonates; alkane sulphonates; dialkyll sulphosuccinates; and fatty acid ester sulphonates.

Primary alkyl sulphate having the formula:

ROS03- 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 detergent active. Linear alkyl benzene sulphonate of the formula R 0\/ -S03- M + where R is linear alkyl of 8 to 15 carbon atoms and M is a solubilising cation, especially sodium, is also a commercially significant anionic detergent active.

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

11 In some forms of this invention the amount of non-soap anionic detergent lies in a range from 8 wt % to 15 wt % of the composition of the tablet or a tablet region.

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 alky! phenols with alkylene oxides, especially ethylene oxide ether alone or with propylene oxide.

Specific nonionic detergent compounds are alkyl C,-22) phenol-ethylene oxide condensates, the condensation products of linear or branched aliphatic C8_20 primary or secondary alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethyl ene-di amine. Other nonionic detergent compounds include alkyl polyglycosides, long-chain amine oxides, tertiary phosphine oxides, and diallky! sulphoxides.

Especially preferred are the primary and secondary alcohol 12 ethoxylates, especially the C9_j, and C12-15 primary and secondary alcohols ethoxylated with an average of from 3 or 5 moles 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 3% to 15%, better 4% or 5% to 10% by weight of the composition of the tablet or a tablet region.

Many nonionic detergent-active compounds are liquids. These may be absorbed onto particles of the composition.

In certain preferred forms of the invention, the tablet or region thereof contains from 30 to 65% by weight (of the tablet or region as the case may be) of particles which contain from 25 to 80% by weight (of these particles) of water-soluble detergency builder and from 20 to 50% by weight (of these particles) of non-soap organic surfactant which may be anionic and nonionic surfactants in a ratio from 5:1 to 1.5:1.

We believe that concentrating most or all of the surfactant surfactantrich particles, and using a substantial proportion of anionic surfaczant -Ls beneficial in providing tablets which have both strength and ellasticity, while allowing the remainder of the tablet composition to contain a substantial proportion of wazer- soluble material which ass 4 ists disintegration of the tablets at the time of use.

13 It is preferred that the weight of the non-soap anionic surfactant in such particles is at least 1.7 times the weight of the nonionic surfactant in them. More preferably, this weight ratio of anionic surfactant to nonionic surfactant lies in a range from 2:1 up to 5:1, and more preferably from 2:1 to 4:1. Preferably these particles contain at least 80% by weight better at least 90% or even 95% of all the organic surfactant present.

It is not necessary to include surfactant as a binder material in the part of the composition outside the surfactantrich particles. Excluding it from this part of the composition is advantageous, to avoid interference with the prompt dissolution of this part of the composition.

Bleach System Tableted detergent compositions according to the invention may contain a bleach system such as 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. However, the invention is particularly applicable when bleach is substantially absent, so that the tablet or region thereof contains no peroxygen bleach, or only a small quantity from 0 to 5% by weight of the tablet or region thereof.

14 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 a- rid aid in the removal of various soils and stains. Suitable enzymes =lude the various proteases, cellulases, lipases, amylases, and mixtures therebf, 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 is composition; and these granules or marumes present no problems with respect to compaction 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-(2morpholino-4- anilino-s-triazin-6-ylamino) stilbene disul-ohonate; and Tinopal CBS is disodium 2,2'-bis-(phenylstyryl) disulphonate.

An antifoam material is advantageously included, especially Lf 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.

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

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, fabricsoftening agents; heavy metal sequestrants such as EDTA; perfumes; and colorants or coloured speckles.

16 Particle Size and Distribution A detergent tablet of this invention, or a discrete region of such a tablet, is a matrix of compacted particles.

Preferably the particulate composition has an average particle size in the range from 200gm to 20OOgm, inore preferably from 250gm to 1400gm. Fine particles, smaller than 180gm or 200gm may be eliminated by sieving before tableting, if desired, although we have observed that this is not always essential.

While the starting particulate composition may in principle have any bulk density, the present invention is especially relevant to tablets made by compacting powders of relatively high bulk density, because of their greater tendency to 4 persion problems. Such tablets exhibit dsintegration and dis 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 400g/litre, preferably at least 500g/litre, and advantageously at least 700g/litre.

Granular detergent compositions of high bulk density pre-oared by granulation and densi f icatio-n in a high-speed mixer/ granulator, as described and claimed in EP 340013A 17 (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.

As mentioned earlier, a tablet may be either homogeneous or may be heterogeneous with more than one discrete region.

It is envisaged that the particles with a high content of phase I sodium tripolyphosphate and also particles of sodium citrate dihydrate will preferably be distributed throughout the whole of a homogeneous tablet. However, it is possible that they will be contained within one or more discrete regions of a heterogeneous tablet, such as a layer or an insert large enough to constitute from 10% to 90% of the weight of the whole tablet. The presence of such a layer or insert could assist break up of the entire tablet when placed in water. A heterogenous tablet may well contain overall the abovementioned proportions of from 5 to 50 wt% detergent active and from 10 or 15 to 80 wt% detergency builder.

Tabletina

Tableting entails compaction of the 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.

18 Tableting may be carried out without application of heat, so as to take place at ambient temperature or at a temperature above ambient. In order to carry out the tableting at a temperature which is above ambient, the particulate com-position is preferably supplied to the tableting machinery at an elevated temperature. This will of course supply heat to the tableting machinery, but the mdchinery 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 g, depending on the conditions of intended use, and whether it represents a dose for an average load in a fabric washing or dishwashing machine or a fractional part of such a dose. The tablets may be of any shape. However, for ease of packaging they are preferably blocks of substantially uniform cross- section, such as cylinders or cuboids. The overall density of a tablet preferably lies in a range from 1040 or 1050gm/litre, better at least 1100 gm/litre up to 1300gm/litre or even above such as up to 1400 gm/litre or more. The tablet density may well lie in a range up to no more than 1250 or even 1200gm/litre.

19 ExaMles and Comparative Exam-ples Exam-o 1 e 1 Tablets for use in fabric washing were made, starting with a spray-dried base powder of the following composition:

Ingredient Parts by Weight Sodium linear alkylbenzene sulphonate 10.5 C.3-1. fatty alcohol 7E0 2.3 C.3-1. fatty alcohol 3E0 2.4 Sodium tripolyphosphate 16.4 Sodium silicate 3.8 Soap 0.3 Acrylate/maleate copolymer 1.5 Sodium sulphate, moisture and minor balance ingredients to 43 Added to the slurry as anhydrous sodium tri-polyphosphate containing at least 70% phase II form.

Particulate compositions were made by mixing this powder with other ingredients as tabulated below. These included particles of sodium tripolyphosphate specified to contain 70% phase I form and contain 3.5% water of hydration (Rhodia-Phos HPA 3.5 available from Rhone-Poulenc).

The compositions all contained, by weight:

Base powder 43% Antifoam granules 3.1% Rhodia Phos HPA 3.5 33% Sodium tri-poly-phosphate Sodium citrate dihydrate or oziher 16% ingredient as specified Perfume, enzymes and other minor Balance to 100% ingredients 40g portions of each composition were made into cylindrical tablets of 44 mm diameter, using a Fette press and applying sufficient pressure to produce tablets of approximately equal strength (as measured by the force to produce fracture).

-est Disintegration of tablets was +. %-ed by means of a test procedure in which a tablet was placed on a plastic sieve with 2mm mesh size which was immersed in 9 litres of demineralised water at ambient temperature of 200C. The water conductivity was monitored until it reached a constant value. The time for dissolution of the tablets was taken as the time (T90) for change in the water conductivity to reach 90% of its final magnitude.

The strength of these tablets was measured by com-pressing t-hem radially, between the platens of a universal materials testing machine until fracture of the tablet occurred. The 21 force at fracture (Fmax) was measured. Also the displacement at fracture was measured and the break energy, which is the area under a force-overdisplacement graph up to failure, was calculated.

The results obtained with sodium citrate dihydrate and other ingredients are set out in the following table:

variable ingredient Frmx Break T90 (Newtons) Energy (rain) 1 (Mi) sodium citrate dihydrate 34 8.9 2.5 sodium sulphate anhydrous 37.3 11.7 4.0 sodium sulphate 7H2C) 34.7 8.5 5.6 sodium carbonate anhydrous 37.5 10.9 3.0 sodium acetate 3H20 37.3 12.6 4.2 Sodium sesquicarbonate 2H20 26.3 12.3 3.0 Sodium bicarbonate 41.3 14.2 3.2 3:1 mixture of sodium 35.7 10.0 2.9 mercarbonate with tetraacetyl-ethylene diamine potassium acetate 39.6 10.5 11.8 Potassium carbonate 1.5H20 47.0 14.6 5.9 urea 29.8 8.9 4.1 is It can be seen from this table that sodium citrate dihydrate gave the best disintegration time when L-he tablets were made at approximately equal Fmax values. Tablets were also made using sodium carbonate decahydrate as the variable ingredient. but were found to be unstable, swelling directly after they were made.

22 Exam-ple 2 The procedure of Example 1 was followed, making tablets of the following compositions:

Base powder 43% Antifoam granules 3.1% Rhodia Phos HPA 3.5 33 to 45% Sodium tripolyphosphate} total 49% Sodium citrate dihydrate or 4 to 16% other ingredient as specified Perfume, enzymes and other minor Balance to 100% ingredients Tablet strength was measured as before. To test disintegration, a test procedure was used in which a tablet was placed in a net bag, and agitated slowly in a standard quantity of water at 200C. After 2 minutes any residue in the bag was collected and dried to constant weight at 5CC.

The variable amounts of HPA 3.5 tripolyphosphate and other ingredients, together with the test results are set out in the following table:

23 Examples Comparative 2.1 2.2 2.3 A B HPA 3.5 33% 41% 45% 33% 33% tripolyphosphate Sodium citrate 16% 8% 4% dihydrate 3:1 mixture of 16% sodium percarbonate with tetraacetyl ethylene diamine Sodium acetate 16% trihydrate Fmax (Newtons) 34 38.8 40.2 38.0 37.3 Break Energy (mi) 8.9 15.4 17.2 11.0 12.0 Residue in net (g) 0.5 0 0 1 12 As can be seen, the three tablet compositions of the invention showed faster disintegration than was observed with comparative example A, while comparative example B was markedly inferior.

24

Claims (10)

1. CLAIMS: A detergent tablet wherein the tablet or a region thereof is a

   corwoacted particulate detergent composition containing (i) detergent surfactant (ii) particles which contain sodium tripolyphosphate with a content of the Phase I form which is more than 40% by weight of the sodium tripolyphosphate in the said particles and wherein the sodium tripolyphosphate in the said particles contains water of hydration in an amount between 1% and 5% by weight of that sodium tripolyphosphate and, (iii) particles of other ingredients characterised in that said other ingredients include particles of sodium citrate dihydrate.
2. A tablet according to claim 1 wherein the sodium tripolyphosphate in the said particles (ii) has a content of the Phase I form which is at least 50% by weight of the sodium tripolyphosphate in these said particles.
3. 3. A tablet according to claim 1 or claim 2 wherein the amount of water of hydration in the sodium tripolyphosphate lies in a range from 2% to 4% by weight of the said sodium tripolyphosphate.
4. 4. A tablet according to any one of the preceding claims 25 wherein the quantity of detergent surfactant is from
5. 5 to 40% by weight of the tablet or region thereof 5. A tablet according to any one of the preceding claims wherein the quantity of detergent surfactant is 8% to 30% by weight of the tablet or region thereof.
6. 6. A tablet according to any one of the preceaing claims wherein the said sodium tripolyphosphate with at least 40% by weight of Phase I form and partial hydration in an amount between 1% and 5% by weight of this tripolyphosphate provides from 25% to 55% of the overall composition of the tablet or region thereof.
7. 7. A tablet according to any one of the preceding claims wherein the amount of sodium citrate dihydrate is from 3% to 20% by weight of the overall composition of the tablet or region thereof.

   is
8. 8. A tablet according to any one of the preceding claims wherein the amount of sodium citrate dihydrate is from 7% to 20% by weight of the overall composition of the tablet or region thereof.
9. 9. A tablet according to any one of the preceding claims 20 wherein the total quantity of the said sodium tripolyphosphate and sodium citrate dihydrate lies in a range from 35 to 60% by weight of the overall composition of the tablet or region thereof.

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10. 10. A tablet according to any one of the preceding claims wherein the tablet or region thereof contains from 30 to 65% by weight (of the tablet or region as the case may be) of particles which contain from 25 to 80% by weight (of these particles) of water-soluble detergency builder and from 20 to 50% by weight (of these particles) of non-soap organic surfactant.