GB Patent 957868 - Process for making a detergent tablet

Description

PATENT SPECIFICATION

NO DRAWINGS.

Date of Application and filing Complete Specification:

Dec 29, 1960.

No 44667/60.

_ Application made in United States of America (No 863,173) _' $\W E on Dec 31, 1959.

Complete Specification Published: May 13, 1964.

Crown Copyright 1964.

Index at Acceptance:-C 5 D( 6 A 5 B, 6 A 5 C, 6 A 5 D 1, 6 A 5 D 2, 6 A 5 E, 6 B 6, 6 B 9, 6 B 10 A, 6 812 B 1, 6 B 12 B 2, 6 B 12 F 1, 6 B 12 F 3, 6 B 12 G 1, 6 B 12 G 2 A, 6 B 12 G 3, 6 B 12 G 4, 6 B 12 H, 6 B 12 K 1, 6 B 12 L, 6 B 12 M, 6 B 12 N 1, 6 B 12 N 2, 6 B 12 N 3, 6 C 9, 6 D).

International Classification:-C 11 d.

COMPLETE SPECIFICATION.

Process for Making a Detergent Tablet.

We, PROCTOR & GAMBLE LIMITED, a British Company, of Hedley House, Gosforth, Newcastle-up-Tyne 3, England, formerly Thomas Hedley & Co Limited, a British Company, of Phoenix Buildings, Collingwood Street, Newcastle-upon-Tyne 1, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: -

This invention relates to a process for making a detergent tablet and to the tablet itself More particularly it relates to a process for making a detergent tablet at commercially feasible production rates which will have sufficient strength to permit packaging and handling without breakage yet be capable of rapid disintegration under ordinary washing machine use.

Tablets of heavy duty synthetic detergent compositions have a number of advantages over their granular and liquid counterparts and are therefore quite desirable The use of tablets of a premeasured quantity of material obviates the need for measuring cups used with granules and liquids and eliminates the usual problems of spilling and over or under usage encountered in employment of granules or liquids Moreover, tablets, because of their size and compactness, are quite useful in dispensing devices such as those which can store tablets and inject them into a washing machine auto matically or which can be placed in public laundries as coin operated machines Be cause they are compressed, tablets take up less space than the same amount of a detergent composition in liquid or granule form.

A number of methods have been proposed 40 to produce detergent tablets, but apparently have not been commercially successful in producing a strong, rapidly disintegrating tablet at high production rates In general, the best method for making detergent 45 tablets, as in most tablet making art, is to compress the ingredients in granular form into a tablet Methods using high pressures have been proposed These methods result in a strong tablet, but one which will not 50 disintegrate rapidly in the ordinary washing machine Additives to effect rapid disintegration of highly compressed tablets, such as C Oo generators, starch or other inert materials are expensive and/or undesirable as 55 ingredients in heavy duty detergent compositions Methods using low pressures have been proposed and result in tablets which are rapidly disintegrating but which are not strong enough to withstand the shocks of 60 packaging, handling, dispensing and the like.

Whether high pressures or low pressures are used, the most effective heavy duty synthetic detergent compositions have a strong tendency to stick to the dies which are used 65 to compress the compositions into tablet form Sticking of the detergent composition to the dies causes breakage of the tablet when the dies are moved apart and when the tablets are ejected Additives which 70 are used in the pharmaceutical tablet making art to prevent ingredients from adhering to the dies are undesirable as additives to the detergent compositions, are difficult to apply to die surfaces and are not effective 75 in continuous production.

C C 957,868 0 41 It is an object of this invention to provide a process for making detergent tablets which are strong, which disintegrate rapidly in water and which are effective detergents.

It is another object of this invention to provide a process for making detergent tablets which overcomes the problem of the adhering of the detergent composition to the dies used in compression thereby permitting rates of tablet production which are commercially feasible.

The invention provides a process for making a detergent tablet from a particulate material comprising a mixture of sodium tripolyphosphate and a water-soluble, noncationic synthetic detergent in which the weight ratio of the sodium tripolyphosphate to the detergent is 9: 1-3: 1, the average density of the particles is 0 5-1 5, and not more than 20 %, by weight, of the particles have diameters less than 02 mm; said process comprising: ( 1) compressing 1 5-2 5 unit volumes of the material into a tablet of one unit volume, at least one of the compressive forces being rotated about the direction of compression so as to apply a shearing force to one or both faces of the tablet, thereby inhibiting adherence of the tablet to the compressing means, the compression pressure being 150-350 p sji so that 40-60 %, by volume, of the tablet should consist of a network of void spaces which are predominantly interparticulate, and ( 2) treating the suface of the tablet with 0.5-5 % of water, by weight of the tablet, so as to hydrate the sodium tripolyphosphate on the surface of the tablet to form a non-chalky, abrasion-resistant surface.

It was found that the use of moderate pressures, i e, in the range 150 to 350 pounds per square inch, results in a tablet which is strong and quickly disintegates if a properly formulated detergent composition is used The use of such moderate pressures overcomes the weakness problems of detergent tablets which are lightly compressed and overcomes the slow disintegration characteristics of the tablets compressed at high pressure.

In order to obtain strong, quickly disintegrating tablets, it is not sufficient to merely use moderate pressures It was found that the particulate mixture being compressed should have the particular characteristics hereinbefore described.

An amount of sythetic detergent corresponding to a weight ratio of sodium tripolyphosphate to synthetic detergent of 9:1 is the minimum permissible for good detergency and the binding effect it exerts on the sodium tripolyphosphate in the tablet.

Higher proportions of sodium tripolyphosphate weaken the tablet and reduce detergent efficiency If the proportion of synthetic detergent is greater than that corresponding to a 3:1 ratio the resulting tablet disintegrates too slowly in water Speed of tablet disintegration increases with increasing amounts of sodium tripolyphosphate 70 The preferred ratio range is 7:1 to 4:1.

The preferred particulate material comprises a mixture containing 40 % to 80 % of a spray dried composition consisting of the synthetic detergent and (if desired) part of 75 the sodium tripolyphosphate, and 60 %' to % unhydrated granular sodium tripolyphosphate, by weight.

Not more than 20 % of the partciulate material should have a particle size (mean 80 particle diameter) smaller than 0 2 mm.

The average density of the individual particles should be in the range 0 5 to 1 5; it is preferably greater than 0 7 The use of a minimum amount of fines and an average 85 particle density in this range is necessary to obtain, upon compression of from 2 5 to 1 5 unit volumes of the aforementioned particulate materials to one unit volume, a detergent tablet having numerous void spaces with 90 in the tablet with a total volume in the range of about 40 %' to about 60 % O of the tablet volume This void space should be predominantly interparticulate, i e, between the particles It was found that a void 95 space which is within this range and predominantly interparticulate is necessary to obtain a strong tablet which will disintegrate rapidly on addition to the wash water A network of voids within the tablets permits 100 the water, in which the tablet is placed for use, to enter into the tablet, displace the air in the voids and disintegrate it rapidly The network of voids communicates with the external air A void space of less than about 105 %' does not provide a network which permits sufficiently rapid disintegration (disintegration in not more than about 3 minutes, preferably not more than about 2 minutes, in an ordinary washing machine containing 110 a load of clothes in water at not less than about 130 F) A void space greater than about 60 % provides a network which makes the tablet too weak.

The void space should be predominantly 115 interparticulate in order to provide a network of voids which is sufficiently continuous to provide rapid disintegration according to the above minimum requirement If the void space is predominantly intrapar 120 ticulate, i e, within the particles, such as that found in the usual low density, hollow, spray-dried granules, (having a density of about 0 2 to about 0 4) such a network is not provided Moreover, such spray-dried 125 granules are so fragile that when they are compressed, they break and an undue amount of fines is formed As mentioned above, the particles of the material to be compressed should not contain more than 130 957,868 of the tablet material to the dies thereby preventing tablet breakage or build up of material which leads to imperfect tablets and eventual clogging of the dies.

Speed of die rotation is not particularly 70 critical but it is generally necessary that the dies be rotated through at least 5 of arc (around the axis of compression) preferably at least about 10 to 25 , during the period of maximum compression This 75 much rotation is generally needed to effect a shearing force between the die and the tablet face If the rotation is insufficient to effect a shearing force, particles of detergent composition will adhere to the dies and 80 score the tablet face or break the tablet.

Die rotation through an arc greater than about 180 can be used but is not necessary and would be difficult to effect at high production rates and might tend to cause 85 friction heat which would adversely affect the tablet ingredients, especially those at the surface.

After the tablet has been compressed as described, it is removed from the die cavity 90 and its surface is moistened with water in an amount of 0 5 to 5 % by weight of the tablet The water is applied preferably by a fine spray but other means such as brushing the water on or subjecting the tablet to 95 steam can be used The water applied to the surface of the tablet hydrates sodium tripolyphosphate on the surface of the tablet and cements tablet ingredients on the surface together to form a strong hard surface 100 on the tablet This surface makes the tablet non-chalky and more abrasion resistant The strong hard surface, however, is porous and the pores communicate with the network of voids within the tablet thereby permitting 105 rapid entry, into the tablet, of the water in which it is placed for use This results in rapid disintegration of the tablet.

The tablet may be then dried if necessary to remove any excess water remaining on 110 the surface of the tablet so that it is dry or at most slightly damp to the touch Much of the water applied to the surface forms a hydrate with sodium tripolyphosphate Drying can be effected in air or preferably by 115 passing the moistened tablets through an oven on a continuous conveyor Three pronged supports such as those used in the ceramic art are useful to support the tablets during surface moistening and drying opera 120 tions.

As mentioned above, the particulate materials used to make the tablets of this invention should comprise sodium tripolyphosphate and a non-soap, water soluble, 125 organic synthetic detergent in the weight ratio range 9:1 to 3 0:1, preferably 7:1 to 4: 1 These detergents may be broadly designated as anionic and nonionic or Eanic synthetic detergents The cationic synthetic 130 % fines, i e, those which are finer than 0.2 mm To avoid breakage and the formation of fines, and to avoid intraparticulate void space, the particles should have an average density in the above mentioned range The material to be compressed can be a mixture of particles of varying densities if the average density falls within this range.

Fine particles are to be avoided because they fill up the interparticulate network to void space within the tablet which is necessary to provide rapid disintegration in the wash water.

The upper size limit of the particles of the material to be compressed is not particularly critical Granular sodium tripolyphosphate and granular and flake synthetic detergents of the sizes commercially available are useful as are the sizes of the usual spray dried and roll dried compositions comprising these ingredients Flakes of synthetic detergent as large as A inch or more in diameter, for example, can be used.

When from 2 5 to 1 5 unit volumes of a material having the characteristics described hereinbefore (ingredients, minimum amount of fines, and density) are compressed to one unit volume using pressures in the range to 350 p s i, a tablet having the proper network of interparticulate void space is obtained The necessary void space in the tablet is not obtained if the unit volume of the material (being compressed to one unit volume) is greater than 2 5 or less than 1 5 Moreover the use of a unit volume of material greater than 2 5 makes difficult the construction of the dies and compressing apparatus The use of a unit volume of material less ithan 1 5 does not provide enough margin to effect satisfactory compression.

During the compression of the tablet ingredients in accordance with the aforementioned conditions, the compressive forces being exerted through the dies should be rotated in order to prevent adherence of the tablet ingredients to the dies The compressive forces exerted against both faces of the tablet should be rotated around the axis of compression with respect to the tablet, and preferably with respect to each other.

That is, the complementary die sections are preferably rotated in opposite directions around a tablet However, the dies may be rotated in the same direction, if the tablet remains stationary, or the tablet may rotate with the dies at a rate of rotation different from the rate of either of the dies The principal requirements are that both dies rotate, that the rotation be sufficient to effect a definite shearing effect between the die surface and the face of the tablet and that there be die rotation during the period of maximum compression Rotation of the dies during this period prevents adherence 957,868 detergents are not suitable because of their relative incompatibility with sodium tripolyphosphate.

The anionic synthetic detergents may be designated as water soluble salts of organic sulphuric reaction products having in their molecular structure an alkyl or acryl radical of carbon atom content within the range 8 to 18 and a sulphonic acid or a ulp Tiuric acid ester radical Important examples of these anionic detergents are: sodium or potassium alkyl benzene sulphonate in which the alkyl group contains from about 9 to about 15 carbon atoms in either a straight chain or a branched chain which is derived from polymers of propylene; sodium and potassium alkyl glyceryl ether sulphonates, especially those ethers of higher fatty alcohols derived from the reduction of coconut oil; the reaction product of higher fatty acids with sodium or potassium isethionate, where, for example, the fatty acids are derived from coconut oil; sodium of potassuim alkyl sulphonates and sulphates, especially those alkyl sulphates derived by the sulphation of coconut or tallow fatty alcohols and mixtures of such alkyl sulphates; sodium and potassium salts of sulphated or sulphonated monoglycerides derived, for example, from coconut oil; sodium or potassium salts of the higher fatty alcohol esters of sulphocarboxylic acids, for example, the sodium salt of the lauryl alcohol ester of sulphoacetic acid; sodium or potassium salts of a higher fatty acyl N-methyl taurine in which the higher acyl radicals, for example, are derived from coconut oil; and others known in the art Examples of other useful anionic non-soap synthetic detergents are dialkyl esters of sodium or potassium salts of sulphosuccinic acid, for example, the dihexyl ester; N-acyl sarcosinates, e g, sodium N-lauroyl sarcosinate The sodium alkyl benzene sulphonates in which the alkyl group contains 9 to 15 carbon atoms are preferred in the practice of this invention.

Non-ionic non-soap synthetic detergents may be broadly classed as being constituted of a water solubilizing polyoxyethylene group in chemical combination with an organic hydrophobic compound such as polyoxypropylene, alkyl phenol, the reaction product of an excess of propylene oxide and ethylene diamine, and aliphatic alcohols.

The nonionic synthetic detergents have a molecular weight in the range of from about 800 to about 11,000.

For example, a well known class of nonionic detergents is available on the market.

These compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol The molecular weight of the hydrophobic base is of the order of 1500 to 1800 The addition of polyoxyethylene radicals to this hydrophobic base increases the water solubility of the entire molecule Liquid products are obtained up to the point where the polyoxyethylene content is about 50 % of the total 70 weight of the condensation product; higher proportions of polyoxyethylene renders the products solid in consistency The molecular weights of three such commercially available products, for example, are 75 approximately 2000, 3000 and 8000 respectively It is preferred to use a liquid nonionic synthetic detergent which is a condensation product, wherein the polyoxyethylene content is not more than 50 % O by 80 weight, of ethylene oxide and the hydrophobic base formed by condensation of propylene oxide with propylene glycol.

Examples of other nonionic synthetic detergents useful in the present invention are: 85 condensation products of 10 to 30 moles of ethylene oxide with one mole of an alkyl phenol containing 6 to 12 carbon atoms, either in a straight or branched chain, in the alkyl groups (e g nonyl or octylphenol); 90 condensation products of 10 to 30 moles of ethylene oxide with one mole of an aliphatic straight or branched chain alcohol containing 8 to 18 carbon atoms (e g lauryl alcohol or tallow fatty alcohol); condensation pro 95 ducts of ethylene oxide and the reaction product of propylene oxide and ethylene diamine wherein the reaction product has a molecular weight of 2500-3000, for example, and the condensation product has a 100 polyoxyethylene content of 40 % to 807;, by weight.

The particulate material used according to this invention should preferably comprise at least 55 %, by weight, of a mixture of 105 sodium tripolyphosphate and synthetic detergent in the ratios mentioned hereinbefore.

Any of the other auxiliary materials generally employed with synthetic detergent compositions can also be included These 110 auxiliary materials can be inorganic or organic and can be mixed with the synthetic detergent and sodium tripolyphosphate in any suitable manner Examples of such conventional inorganic auxiliary materials 115 are alkali metal silicates, carbonates, sulphates and phosphates (e g metaphosphate, pyrophosphate and orthophosphate) Examples of organic auxiliary materials are carboxymethyl cellulose, suds builders (e g 120 coconut fatty acid mono and di-ethanolamides and lauryl dimethyl amine oxide), Nchloro bleaches, tarnish inhibitors, fluorescent brightening agents, bacteriostatic agents, perfumes, colouring matter, suds depressors 125 and the like.

The particulate material to be compressed preferably contains from 0 75 to 4 5 % moisture (by weight of the total amount of particles) which acts as a binder for the tablet 130 957,868 preferred material to be compressed in accordance with this invention comprises % to 20 % of unhydrated granular sodium tripolyphosphate and 40 % to 80 % spray dried granules containing synthetic deter 70 gent and any remaining sodium tripolyphosphate.

The spray dried granules contain part of the sodium tripolyphosphate iin the tablet formulation, all of the non-soap synthetic 75 detergent and any of the minor ingredients, such as sodium sulphate, moisture, nonionic binder, brightening agents or anti-redeposition agents, which are included Spraydried granules in the above range are pre 80 ferred because the process of spray drying is a convenient way to ensure that the minor components, if any, of the usual detergent compositions are uniformly distributed throughout the material 85 Unhydrated granular tripolyphosphate in the above range is preferred because it reduces the quantity of product to be spray dried, and more important, it permits the formation of a stronger porous surface on 90 the tablet than is obtainable using 100 % spray dried granules Since the process of spray drying hydrates much of the sodium tripolyphosphate in the composition being dried, tablet surface hardening by the appli 95 cation of water to compressed spray dried granules is effected mainly through the cementing together of the tablet ingredients and only partially through further hydration of sodium tripolyphosphate By including 100 unhydrated sodium tripolyphosphate in the compressed tablet ingredients a greater degree of hydration is effected during the water treatment of the tablet surface thereby making the porous tablet surface harder and 105 stronger and more like a hard porous shell.

Such a shell is nevertheless rapidly disintegrable in the wash water.

The tablet forming apparatus used to perform the process of this invention can be 110 any device which provides a cavity for holding the particulate material to be compressed, opposing dies, both of which can be rotated with respect to the tablet faces, and a means for compression of the particu 115 late material by exerting pressure on at least one of the dies Tablet making machines known in the art can be adapted to these requirements.

Because of the requirement of rotary 120 compressive forces, the tablets of this invention will usually be round or nearly so in at least one dimension A suitable tablet press is described in the Specification of our

Applicant No 44668/60 (Serial No 125 957,869).

The following examples are given to illustrate the manner in which this invention can be practised.

ingredients, i e moisture assists the nonsoap synthetic detergent in causing the compressed particles to stick together, The moisture content of the material to be compressed can be adjusted by using ingredients which already contain moisture (e g.

spray dried granules) or if the ingredients are too dry, moisture can be added But overall it should preferably be less than 4 5 % A greater amount of moisture results in an undue reduction in the amount of void space when moderate compression pressures are used Moisture can be uniformly added to the material, if necessary, by spraying water onto the particles in a rotary drum or a moving belt for example.

The preferred moisture content is 1 % to 3 % by weight.

Although water in the amounts indicated adequately achieves the desired binding, greater adherence between the compressed particles can be produced if desired by uniformly adding, to ingredients containing adequate moisture, up to 3 % (by weight of the total amount of particles) of a liquid nonionic synthetic detergent as an auxiliary binding agent However, when the moisture content is too low to give adequate binding, the nonionic synthetic detergent can be relied on as the primary binding agent.

Thus, amounts of liquid nonionic auxiliary binding agent from 0 % to 3 % by weight, may be used; amounts from 0 25 to 1 5 % are preferred The liquid nonionic poducts mentioned hereinbefore are preferred as the auxiliary nonionic binding agent.

The uniform addition of moisture and/or liquid nonionic detergent to the material to be compressed is intended to include those situations where the moisture and/or nonionic detergent is uniformly added to a portion of the material, which portion is then uniformly mixed with the remainder of the material which may be dry and may contain no nonionic detergent The portion containing the moisture or nonionic detergent is preferably at least 40 % of the total material, by weight.

The liquid nonionic synthetic detergent can be added to the particles by spraying it on the particles or a portion of the particles to coat such particles The nonionic detergent can be sprayed on the granules in a rotary drum or a moving belt for example.

The nonionic detergent being sprayed on can be diluted with water if desired.

The particulate material to be compressed in accordance with the process of this invention may comprise a uniform mechanical mixture of the individual components, a homogeneous mixture such as that obtained by spray drying or roll drying an aqueous slurry of the ingredients, or a mechanical mixture of the ingredients a portion of which constitutes spray dried granules The 957,868 EXAMPLE I.

A spray-dried granular detergent com.

position having the following composition was formed:28 parts sodium tripolyphosphate parts sodium alkyl benzene sulphonate (the alkyl radical being derived from polypropylene and averaging 12 carbon atoms) I 0 27 parts sodium sulphate 14 parts sodium silicate having an Si O 2 to Na 2 O ratio of 2:1 0.7 parts sodium carboxymethyl cellulose 0.14 parts Optical brightener 28 parts xa 1: 1 mixture of two condensation products of ethylene oxide and the reaction product of propylene oxide and propylene glycol They had molecular weights of about 8000 and 3000 respectively 2.8 parts of a mixture of hydrogenated fish oil fatty acids (a suds depressor described in British Patent Specification No.

808,945) 4 parts moisture The moisture of nonionic proproducts was added to chemically de-aerate the crutcher mix which was spray dried in order to obtain high density granules.

See British Patent Specification

No 812,249.

The spray dried composition had a density of 0 5 to 0 92 % (by weight of the spray dried granular composition) of liquid nonionic reaction product of propylene oxide and propylene glycol, having a molecular weight of 3000, was sprayed uniformly on the granules in a rotary drum This added nonionic detergent was used to act as a binding agent during tablet compression.

The granules were then subjected to an air lift, a gravity separator and a screen whereby the moisture content was reduced to 3 % by weight, and particles larger in size than 1.4 mm and most of the particles smaller in size than 0 2 mm (mean diameter) were removed The resulting spray dried composition contained 18 % by weight, of particles having diameters less than O 2 mm.

990 parts of this spray dried composition were uniformly mixed with 840 parts of anhydrous granular sodium tripolyphosphate which contained 2 % by weight, of particles with diameters less than 2 mm The density of the sodium tripolyphosphate was 1.3 The resulting mixture contained 1 7 % by weight, of moisture substantially all of which was in the spray dried granules The mixture contained 10 6 % by weight, of particles with diameters less than 2 mm The average particle density of the mixture was 0.85 2 parts by weight of perfume were 65 sprayed on the mixture.

6.2 cubic inches of the mixture were charged into a tablet cavity having a diameter of 2 25 inches One tablet die was forced onto the mixture with a pressure of 70 p s i to form the mixture into a tablet having a volume of 3 2 cubic inches Both the compression die and the non-yielding die opposing this die were rotated with respect to the tablet The non-yielding die 75 was rotated through an arc of 10 during the period of maximum compression The compression die was rotated in a direction opposite to that of 'the non-yielding die through an arc of 10 during the first part 80of the period of maximum compression and in the same direction as that of the compression and in the same direction as that of the compression die through an arc of during the last part of the period of 85 maximum compression The rotating dies exerted a definite shearing force on the faces of the tablet being formed.

There was no tendency for the tablet or the tablet ingredients to adhere to the dies 90 which, when drawn apart, permitted the tablet to be easily removed The tablet was then placed on a three pronged support and passed through a chamber where the entire surface of the tablet was subjected to a fine 95 spray of water During this treatment 2 5 % water (by weight of the tablet) was added to the tablet surface The tablet was then placed in a drying oven at 250 F for 1 5 minutes Sodium tripolyphosphate on the 100 surface of the tablet was hydrated and detergent ingredients on the surface of the tablet cemented together forming a nonchalky, abrasion-resistant, porous surface on the tablet When the tablet was removed 105 from the oven it was only slightly damp to the touch and was ready for packaging It weighed two ounces and had a total moisture content of 3 3 /o It had a network of voids amounting to 45 % of the volume of the 110 tablet This network was predominantly interparticulate.

The finished tablets were economically, conveniently and successfully handled and packaged with the aid of high speed ma 115 chinery The finished tablets, when placed in an ordinary washing machine containing a load of soiled clothing in water at 130 F, disintegrated in 80 seconds The detergency effectiveness of the tablets was excellent 120 The condensation product of lauryl alcohol and 15 moles of ethylene oxide or the condensation product of 15 moles of ethylene oxide and nonyl phenol can be substituted in equivalent amounts for the liquid 125 nonionic sprayed on the spray-dried granules in Example I with substantially similar results.

Compression pressures of 250 p s i and 957,868 pression Both dies were rotated through 65 an arc of 10 around the axis of compression and in opposite directions The rotating dies exerted a definite shearing force on the faces of the tablet being formed.

There was no tendency for the tablet or 70 the tablet ingredients to adhere to the dies which, when drawn apart, permitted the, tablet to be easily removed The entire surface of the tablet was then sprayed with water in an amount equivalent to 2 5 % by 75 weight of the tablet The tablet was permitted to dry in air at room temperature.

Sodium tripolyphosphate on the surface of the tablet was hydrated and detergent ingredients on the surface of the tablet 80 cemented together forming a non-chalky, abrasion-resistant, porous surface on the tablet.

: The tablet weighed 2 ounces and had a total moisture content of 3 % by weight 85 It had a network of voids amounting to % of the volume of the tablet This network was predominantly interparticulate.

The tablet was strong and showed no signs of breakage when subjected to the 90 stresses and handling typical of packaging and transporting operations When the tablet was placed in an ordinary washing machine containing a load of soiled clothing in water at 130 F, it disintegrated in 90 95 econds The detergency effectiveness of the tablet was excellent.

Sodium lauryl glyceryl ether sulphonate, sodium N-oleoyl N-methyl taurate, sodium lauryl sulphate, potassium oleoyl isethionate 100 or a nonionic condensation of ethylene oxide having a molecular weight of 8000 (described above) can be substituted in equivalent amounts for the alkyl benzene sulphonate in Example I with substantially 105 equal results.