US3247122A - Detergent tablet and process of preparing same - Google Patents

Description

United States Patent 3,247,122 DETERGENT TABLET AND PROCESS OF PREPARING SAME Bernard Richard Schaa-fsma, Midland Park, and Albert Lyle Schulerud, Nutley, N.J., assignors to Colgate- Palmolive Company, New York, N.Y., a corporation of Delaware No Drawing. Filed July 30, 1962, Ser. No. 213,116 9 Claims. (Cl. 252-135) The present invention relates to an improved process for making detergent tablets. More particularly the invented process is of a method of producing such tablets which facilitates their commercial manufacture, even when production must be temporarily interrupted for such causes as mechanical breakdowns, cleaning of equipment and absence of the operator of the processing equipment. The invention also includes detergent tablets of a new composition.

In the production of lightly compacted detergent tablets, made from small detergent particles, it has been found that certain formulas comprising non-cationic synthetic organic detergent, water soluble silicate, water soluble polyphosphate and Water result in a quickly disintegrating tablet, completely soluble in water, which is of a low bulk density and is capable of withstanding shipping shocks withoutfracture. In the production of such a tablet, moisture is added to detergent composition particles before they are pressed to tablet form. By following the novel procedures of the present invention, the ease of manufacturing such tablets can be dramatically increased. This is so, due to the addition-of a small proportion of water soluble sulfate to the detergent composition, which makes detergent particles which can be moistened and which show little tendency to agglomerate objectionably moistening, despite remaining quiescent for substantial periods of time. Detergent tablets can be produced without the presence of the water soluble sulfate but the ease of processing obtainable by the present method represents a distinct improvement which was not expected from the prior art or practice.

In accordance with the present invention a process for manufacturing a detergent tablet comprises producing a particulate detergent composition comprising about 2 to 20% of a non-cationic synthetic organic detergent, about 25 to 40% of a water soluble polyphosphate, about 20 to 50% of a water soluble metal silicate, about 3.5 to 10% of water soluble sulfate and up to about water, moving and circulating a mass of said particulate detergent, adding 2 to 30% water to the moving and circulating particulate detergent to raise the moisture content thereof to 17 to 30% and lightly compacting the resulting particles to form retaining tablets which are readily disintegrable in wash water, soluble therein and resistant to breakage when subjected to shipping shocks.

The non-cationic synthetic organic detergent is usually a nonionic detergent, preferably one comprising both hydrophilic and hydrophobic portions in the molecule of which at least the hydrophilic portion includes a plurality of lower joined alkylene oxide groups. A preferred detergent of this type is an alkyl phenol having a poly lower alkoxy alkanol joined to the phenolic oxygen. Nonyl phenoxy polyoxyethylene ethanol, comprising about 9 to 10 ethoxy groups, has been found to be an excellent nonionic detergent of the present invention. Usually, instead of nonyl, the alkyl group may be of 6 to 14 carbon atoms and the alkoxy chain may be of 4 to 12 alkoxy units, each unit comprising from 2 to 4 carbon atoms. Although the above-mentioned phenolic derivatives are of a special importance in this invention, mixtures of nonionic detergents may also be employed. Thus, other nonionics, including the block copolymers of ethylene oxide and 'propylene Patented Apr. 19, 1966 oxide (Pluronics), reaction products of higher fatty alcohols and lower alkylene oxide (Emulphogene), polyoxyethylated higher fatty acids (Emulphor), polyethoxy and poly lower alkoxy esters and ethers of poly alcohols, especially of sorbitol and mannitol (Span, Tween) may be used with the alkyl phenoxy polyoxyalkylene alkanol and in replacement thereof, where desired. Whether a single type of nonionic detergent or a mixture thereof is used, the proportion should be within the range of 2 to 20%, preferably 5 to 15 or 6 to 14% of the detergent briquette. All percentages of constituents in this specification and in the appended claims are on a tablet weight basis.

In addition to the nonionic detergent one may have present in the detergent tablet, as replacement of some of the nonionic detergent, an anionic detergent, usually added primarily to produce additional foam, when desired and to contribute its cleaning power to the composition. In some cases it may be found desirable to replace nonionic detergent with a suitable anionic material. A preferred anionic detergent is sodium alkyl benzene sulfonate, especially sodium tridecyl benzene sulfonate. This material is a mixture of detergents produced by alkylating benzene with a blend of propylene tetramer and pentamer. The alkyl groups are highly branched but other alkyls of relatively straight chain configuration are also useful in these compounds, providing that they are of 12 to 18 carbon atoms. The anionic detergents are generally employed as their water soluble sodium salts but other Water soluble metallic salts, such as the alkali metal salts, e.g., potassium salts, may be used too, usually in partial replacement of some of the sodium salt. Instead of alkyl aryl sulfonates, other anionic organic detergents of the sulfated or sulfonated type are useful. Of these, one may mention sodium lauryl sulfate, sodium coconut oil fatty acids monoglyceride sulfate and sodium salts of a higher fatty acid amide of N-methyl taurine. It will be seen that these compounds contain a fatty alkyl or acyl group of 10 to 18 carbon atoms, as the lipophilic portion of the molecule and are utilized as their water soluble salts, preferably alkali metal salts. The proportion of anionic detergent which may be used to make a detergent tablet is complementary to that of the nonionic detergent. In other words, the sum of both types of detergent material present should not be in excess of about 20% and not less than about 2% of the detergent briquette.

The water soluble metal silicate is a constituent of the present briquette which has the unusual effect of aiding the production of a briquette which-is form-retaining and resistant to breakage, although pressed at a low pressure,

and still disintegrates rapidly in aqueous media and dissolves completely in a short time. The silicates allow making of tablets of low bulk density and do not require coating of the tablets. Of the silicates that have been found useful, those which are alkali metal salts, especially sodium silicates, and which are of a ratio of metal oxide to silica, by weight, of about 0.3 to 0.6 are most often used. A highly preferred silicate is sodium metasilicate having a Na O:SiO ratio of 1:235. However, other silicates of the general type described may also be included in the present briquettes, either together with or in replacement of this particular silicate, to obtain similar effects.

The water soluble polyphosphate is a metal salt, usually an alkali metal salt and preferably the sodium salt of a polyphosphoric acid. Among such salts, the most preferable are pentasodium tripolyphosphate and tetrasodium pyrophosphate. Other polyphosphates of satisfactory builder action, Which also enable one to produce improved briquettes, according to the present invention, may be employed in mixture with the described sodium polyphosphates or in replacement thereof. Either the sodium or potassium salts of these materials are used, depending upon the particular properties of the final product desired. The water soluble sulfate is the material which, when presentin the detergent particles to be moistened, together with the other detergents and builders mentioned, has the unexpectedly beneficial effect of improving processing properties markedly. The sulfate is usually an inorganic compound, generally a metal salt. Most preferred of these is sodium sulfate but other alkali metal sulfates, e.g., potassium sulfate, may be employed providing that they have the same general effect with the composition to which they are added. In addition to the four constituents described, water must be present in the final tablets. Also, adjuvants which are useful to give the detergent briquette special desirable properties may be ineluded. Among such substances are additional builders, foam enhancers or suppressors, coloring agents, per fumes, bleaches, solvents, fluorescent dyes, anti-redeposition agents and so forth. The total proportion of adjuvants employed should be a minor one, to avoid any interference with the desirable physical properties of the detergent briquette.

The proportions of non-cationic detergent, silicate, polyphosphate, sulfate and water should be regulated in accordance with the following teachings so as to obtain a product which can be economically and efficiently manufactured by the method herein described and which will still be of satisfactory strength and solubility properties. The proportion of the synthetic organic detergent should be held within the range of 2 to 20% and is preferably 6 to 14%, most preferably about It has been found that, in conjunction with the silicate and phosphate, such a percentage of organic detergent will give excellent cleaning results and will not interfere with the production of a strong, yet quickly dissolving tablet. Lesser proportions than the minimum of this detergent will not have a satisfactory cleaning effect and higher proportions will often interfere with the desired tablet properties. The water soluble phosphate present should be 25 to 40% of the briquette, preferably about 30%. Such percen tages of these materials contribute excellent building and detergent properties to the product and complement the silicate to allow the production of a quick dissolving tablet of adequate strength and abrasion resistance. Also, such proportions of the polyphosphate may be completely hydrated by some of the water present, leaving additional moisture to aid in making the silicate more readily soluble in the wash water.

The water oluble silicate comprises to 50% of the briquette andit has been found that such a proportion of silicate is desired to obtain a product which will dissolve rapidly and yet which will be of excellent resistance to breakage during normal shipping. A preferred proportion of silicate is 20 to 40% and about 30% is considered best. The silicate constituent of these products, when employed in these proportions, exhibits a dramatic effect in modifying the tablet properties, making the tablet lighter, yet stronger, helping the particles to be joined together more tightly, so as to diminish a tendency to break under rough handling, yet promoting very rapid solubility. These beneficial results may be obtained without surface coating the detergent briquettes, which is unexpected. The proportion of Water present in these briquettes is important to obtain a satisfactory product having the properties discussed previously. The water substantially or completely hydrates the polyphosphate and also greatly improves the solubility of the silicate, so that virtually no insoluble grains are found in wash water into which briquettes have been placed. Seventeen to 30% of water in the invented briquettes will accomplish these results and it is preferred to employ 19 to of water in most of the invented compositions, most preferably 21 to 23% whereby substantial hydration, e.g., 75% hydration or more, of the polyphosphate takes place. Moisture added to the particulate 4 detergent is 2 to 30%, preferably 7 to 17%. It has been found that within the ranges mentioned more water can be included in the briquettes when silicates of lower ratios of Na O:SiO within the 0.3 to 0.6 range, are used.

The proportion of sodium sulfate in the detergent tablets to obtain improved processing properties is from 3.5 to 10%. This may be obtained by producing a particulate detergent having about 4 to 12% sodium sulfate therein, allowance being made for the decrease in the proportion of the sodium sulfate caused by addition of moisture. With respect to the other constituents of the invented tablets, the same percentage ranges were given for both the final tablet and the particulate detergent composition from which it is made, to avoid unnecessary inclusion of additional ranges of constituents in the particulate detergent. It is understood that the ranges given primarily describe the final product and the crutcher mix composition and particulate detergent composition will usually be chosen accordingly.

When 3.5 to 10%, preferably about 7%, of sodium sulfate is included in the detergent tablet, it is found that moving and circulating of the mass of particulate detergent to which water has been added may be suspended for as long as an hour Without any detrimental agglomeration of the product into lumps or units of undesirable size and hardness. Thus, should it be required to halt mixing or should some material have to be held before pressing, this can be done without the necessity for scapping of treated detergent. Also, production can be made more efficient because a holdup reservoir or bin may be installed before the presses and it is not essential that the pressing rate be exactly equal to the rate of feed from the spray tower to the apparatus in which the particles are moistened.

To manufacture the present detergent tablets, a particulate detergent is produced in which the organic detergent, sulfate, silicate and. polyphosphate are present. It is highly preferred that such detergent composition constituents be homogeneously distributed throughout the articles and spray dried detergent beads have been found to be an excellent starting material for making these briquettes. In the spray drying operation, one makes a solution or slurry of the detergent materials in an aqueous medium, usually adding to this crutcher mlx useful adjuvant substances which are not adversely affected by spray drying. Normally, the crutcher mix will be of a solids content within the range of about 40 to 60%. This aqueous dispersion or solution is then pumped through spray nozzles and is dried in a path of heated drying gas, through which it usually falls to a collector. The particles produced may be cooled, screened and classified to remove objectionably large or small material. The product resulting may be somewhat irregular in shape but is usually considered to be composed of bodies which are hollow and of approximately spherical shape. Those of particle size such that over pass through an 8 mesh sieve and do not pass a mesh sieve, a US. Standard Sieve Series, are excellent beads to be converted into briquettes or tablets. During the drying operation most of the Water present in the crutcher mix is removed but there may be left in the particles up to about 15% of moisture, and usually at least 1% is present.

The homogeneous detergent composition particles may be produced by other methods than spray drying. For example, spray cooling, agglomeration, even crushing, followed by screening and classification, may be employed to produce the desired particles. Also, a portion of the product may be spray dried and to this may be separately added organic detergent, silicate and phosphate. However, it is considered important to have a substantial proportion of the silicate present, at least about 75% thereof, present with the phosphate and organic detergent and distributed throughout each of the particles, as in a spray dried composition.

The particles of detergent composition, high in silicate content, as described above, are placed in continuous motion as in la tumbling drum, and while moving, moisture is sprayed onto the particle surfaces in fine droplet form and in amount to produce a final product having a moisture content of 17 to 30%, preferably 19 to The continuously moving and circulating particles may adhere lightly to a number of other particles, in the course of spraying and circulating them. Before moistening, the detergent beads are of an apparent density of about 0.2 to 0.6 gram per cubic centimeter. After moistening, this density may be altered somewhat, usually being decreased, e.g., by as much as This result is attributable to the moistening of the relatively large proportions of silicate together with polyphosphate and the resulting swelling of materials and increase in average particle size.

Adequate and uniform moistening of the detergent beads or granules high in silicate content maintain the silicate in a readily soluble condition so that no undissolved silicate deposits on clothing being Washed. This is of importance to the detergent chemist because silicates tend to become more insoluble when heated to drive off the moisture accompanying them, as is done in spray drying. Also, the polyphosp'hates preferentially attract moisture, thereby often tending to reduce the silicate to a less soluble state. Even when placed in an excess of water, as in the washing machine, such silicates may not dissolve completely during the wash cycle, leading to objectionable particles left on the articles being laundered. On the present detergent briquettes however, due to the relatively high concentration of silicate solution produced when the composition high in silicate content is moistened, any silicate of lower solubility is soon made more soluble. This more soluble form or condition persists for long periods of time after moistening, and the briquette produced therefrom is still completely soluble, months after it is made. A most even distribution of moisture in the detergent and an absence of excessive agglomeration are noted when the material beingmoistened is kept in continuous motion and the moisture is applied in fine droplet form. Mixing, moistening, and agglomeration to a desired extent may be followed by screening the pressed detergent to desired particle size range. It has been found preferable to have the particles between 4 and 40 mesh, US. Standard Sieve Series, but other size ranges may be utilized. When moisture is added to particles initially of very low moisture content, it has been usually found more difiicult to add large proportions of moisture, within the ranges mentioned, than to add lesser amounts thereof. Also, it is usually desirable to add more than the minimal proportion of moisture when the particles are initially comparatively dry. The operator of the mixing equipment will normally adjust his mixing techniques, speeds, and times to produce the most desirable moistening of the detergent particles. Also, two-step addition of moisture may be found desirable, wherein an initial amount of moisture is added, mixed for a sufficient length of time, perhaps 5 minutes to as long as one-half hour, and then a second addition of moisture is made. By this technique, one can add larger percentages of water to the detergent particles and still obtain excellent pressable material. As mentioned, mixing speeds may be adjusted, as may mixing times. However, mixing speeds of 100 to 250 lineal feet per minute, at the exterior of a rotating drum, equipped with internal bafiies have been found useful. Mixing times of as little as one minute can give acceptably moistened detergent particles.

Due to the presence of the sulfate in this composition, the moistened product is not sensitive to undesired aggregation into lumps or concrete masses. Thus, the moistened detergent may be held as long as an hour or more in some instances and will still be free flowing, suitable for transport to the press. The reason for the unexpected effect of the rather specific proportions of sulfate is not known, although it is theorized that the sulfate enters into and regulates the speed of hydration of the other salts present, thereby changing the type of aggregate produced.

After moisture has been added to the silicatecontaining detergent particles, they are pressed at a low pressure into a desired briquette form. The pressure employed may be any suitable low pressure, it having been found that pressures from 3 to 25 pounds per square inch may be used advantageously in pressing a table, which is most often from about A to 1 inch thick. Pressures over pounds per square inch should be avoided. Pressing is preferably effected between opposed dies having Teflon or chrome plated surfaces and cavities. After pressing, it is unnecessary to submit the product made to any special treatment or aging period before it may be shipped although as ignificant increase in strength is observed within about an hour after pressing. The detergent briquettes prepared are of suflicient strength to withstand shipping without breaking or being severely abraded and they may be packed in any usual way. It has been noted that the briquettes made often have highly desirable low densities, making a tablet whose larger volume is easier for the user to employ and which facilitates subdivision into small units, where accurate control of the detergent concentration employed is considered important. It is considered unpredictable that the detergent powder and tablet bulk densities should be of such desired low densities in the claimed formulas, from 0.2 to 0.6 gram per cubic centimeter, since previous observation indicated that sulfates tended to increase such densities. Surprisingly, too, the lighter briquettes are even stronger than comparable heavier materials made with less silicate. They are made by a more efficient process and can be produced by tableting and briquetting equipment of conventional design. Due to the elimination of a coating operation, heretofore considered to be necessary and still considered important for many other detergent tablet formulations, production rates and efficiency can be increased. Furthermore, all this is accomplished without the necessity for inclusion of comparatively expensive conditioning or adjuvant materials in the detergents.

Although it is'unnecessary to coat the detergent to make a satisfactory product of this invention, moisture may be sprayed onto the surfaces of the finished briquettes, if so desired. Also, it may sometimes be considered desirable to deposit a thin film of organic polymer, such as sodium carboxy methyl cellulose or polyvinyl alcohol on the products made, to further harden them and make them suitable for withstanding extremely severe handling. Gther variations of the described process will be apparent to one of skill in the art but the described invention makes a useful product and modification of the production method is not necessary, although it may sometimes be desirable. In some cases it is possible that the moistening solution may include adjuvant materials not stable to heat, e.g., emulsified perfumes. Some sodium silicate may be added with that solution. Products produced may subsequently be perfumed, colored, wrapped and packed for shipment. It is preferred to pack them in moisture tight wrappers, e.g., sleeves of polyethylene film, but they are still resistant to breakage and are usefully soluble, even when stored for months at atmospheric conditions.

Products made according to this invention have been subjected to severe testing and usually, after aging, a briquette can stand at least five shocks equivalent to a free fall of four feet onto a hard surface before it starts to break apart. Also, when packed in polyethylene sleeves, the briquettes do not become abraded objectionably, despite repeated shaking in a package, which simulates a type of rough handling to which they may be subjected in shipping. Still, despite their great strength,

the tablets dissolve quickly and completely, usually disintegrating completely within 45 seconds and most often in 10 to 30 seconds. The following examples are included to illustrate embodiments of the invented process and products. They are not to be considered as limiting the invention. All proportions are by weight, unless otherwise indicated.

An equeous crutcher mix was made of all the above materials except the pigment and the approximately 55% solids mix was sprayed at a pressure of about 300 pounds per square inch and at a temperature of 135 F. into heated drying gas at an initial temperature of about 600 F. The particles obtained, of about 8 to 100 mesh, were of a moisture content of about 10%. They were sprayed with a fine spray of water while being tumbled for to minutes in a slightly tilted drum rotating at a peripheral linear speed of about 100 to 250 feet per minute. Sprayed product was continuously removed at a moisture content of 21% and was screened to 4 to 40 mesh (through 4, on 40 mesh), after which it was held for periods up to an hour and pressed. This product may also be held several hours and is still pressable. It does not lump objectionably on storage.

The powder before pressing is of a bulk density of about 0.25 gram per cubic centimeter, the spray dried powder being approximately 0.3 gram per cubic centimeter. It is pressed to a chamfered flat cylinderical tablet of 2% inches diameter by 0.815 inch thickness, weighing 1.3 ounce, being of a bulk density of about 0.5 gram per cubic centimeter. Pressing was at a pressure of about 5 to 25 pounds per square inch.

The tablet made was an excellent laundry detergent. It was quickly disintegrable in wash water in a typical washing machine. When tested by dropping 2 feet onto an end, immediately after manufacture it did not break up. After aging several hours or overnight the tablet strength even increases, as it does when 2 to.5% moisture is sprayed onto the tablet surface followed by drying off of such added moisture.

Example II Ingredient:

Higher alkyl phenol polyethylene ethanol (alkyl of nine carbon atoms and polyoxyethylene ethanol chain averaging 9.5 ethyl- Parts ene oxide groups) 10.4 Sodium tripolyphosphate 32.3 Sodium silicate (Na O:SiO =1:2.35) 31.6 Sodium sulfate 3.5 Water 21.0 Adjuvants 1.2

8 placed in the wash water in a washing machine. Its abrasion resistance was very high, due in part to the post treatment with water.

This formula resulted in moistened beads which did not lump, and were mobile enough to be moved by and to processing equipment, even after as much as /2 hour of quiescent storage. In this respect it was far superior to a similar formula less the sulfate constituent.

' Example III Ingredient:

Parts Ethoxylated nonyl phenol (9 to 10 ethylene oxides per mole) 10.0 Sodium tripolyphosphate (including phosphate products of spray drying) 40.0 Sodium silicate (Na O:SiO ratio of 112.35) 20.0 Sodium sulfate 8.0 Adjuvants (pigment, fluorescent dyes, perfume, inert materials) 1.0 Water 21.0

The above formula is for a detergent briquette processable by the method of Example II. The product obtained is acceptable as a laundry detergent tablet, although the detergent particles produced are of higher bulk density than those made with more silicate. In part, this effect may be attributable to the spray properties of the crutcher mix and subsequent differences in moistening effects. The detergent particles processed well and did not lump objectionably or exhibit a laziness after standing.

Example IV A tablet of formula like that of Example II was made, except for replacement of the 3.5 parts sodium sulfate with 10.0 parts and the changing of the moisture content to 23%. The product produced was comparable to that of Example II and processed readily, exhibiting no laziness.

The invention has been described with reference to several examples thereof. It is not to be limited thereto and its scope is determined by the claims and processes and products equivalent to those claimed.

What is claimed is:

1. A process for manufacturing a detergent tablet which comprises producing a particulate detergent composition comprising 2 to 20% of a water-soluble synphilic and hydrophobic portions in the molecule in which at least the hydrophilic portion includes a plurality of lower joined alkylene oxide groups or mixtures thereof, 25 to 40% of a water-soluble alkali metal polyphosphate, 20 to 50% of a water-soluble alkali metal silicate, 4 to 12% of a water-soluble alkali metal sulfate and up to about 15% water, moving and circulating a mass of said particulate detergent, adding 2 to 30% water to the moving and circulating particulate detergent to raise the moisture content thereof to 17 to 30% whereby the moisture is substantially uniformly distributed throughout the mass of said particles. and lightly compacting the resulting particles at a pressure of 3-100 p.s.i. into form retaining tablets which are readily disintegrable in wash water, soluble therein and resistant to breakage when subjected to shipping shocks.

2. A process for manufacturing a detergent tablet which comprises spray drying a particulate detergent composition comprising 2 to 20% of a water-soluble nonionic detergent containing both hydrophilic and hydrophobic portions in the molecule in which at least the hydrophilic portion include-s a plurality of lower joined alkylene oxide groups or mixtures thereof, 25 to 40% of a water-soluble alkali metal polyphosphate selected from the group consisting of pyroph'osphates and tripolyphosphates, 20 to 50% of a water-soluble alkali metal silicate having a metal oxide to silica ratio between 0.3 and 0.6, 4 to 12% of water-soluble alkali metal sulfate and up to water, moving and circulating a mass of said particulate detergent, adding 2' to 30% water to the moving and circulating particulate detergent to raise the moisture content thereof to 17 to 30% whereby the moisture is substantially uniformly distributed throughout the mass of said particles and lightly compacting the resulting particles at a pressure of 3-100 p.s.i. into form retaining tablets which are readily disintegrable in water, soluble therein and resistant to breakage when subjected to shipping shocks.

3. A process for manufacturing a detergent tablet which comprises spray drying a particulate detergent composition comprising 6 to 14% of a nonionic synthetic organic detergent which is a higher alkyl phenol poly lower alkoxy alkanol, 25 to 40% of a water-soluble alkali metal tripolyphosphate, to 40% of a watersoluble alkali metal silicate of metal oxide to silica ratio between about 0.3 and 0.6, 4 to 12% of water-soluble alkali metal sulfate and up to 15 water, moving and circulating a mass of said particulate detergent, adding 2 to 30% water to the moving and circulating particulate detergent to raise the moisture content thereof to 17 to 30% whereby the moisture is substantially uniformly distributed throughout the mass of said particles and lightly compacting the resulting particles at a pressure of 3-100 p.s.i. into form retaining tablets which are readily disintegrable in water, soluble therein and resistant to breakage when subjected to shipping shocks.

4. A process for manufacturing a detergent tablet which comprises making an aqueous mixture of a detergent composition comprising 6 to 14% of a nonyl phenol polyoxyethylene ethanol in which the polyoxyethylene ethanol is of 9 to 10 oxyethylene units, to 40% sodium tripolyphosphate, 20 to 40% sodium silicate of Na O:SiO ratio of about 0.4, 4 to 12% of sodium sulfate and 8 to 12% water, spray drying the aqueous mixture in a heated drying gas to a particulate detergent of such composition, moving and circulating a mass of said particulate detergent, adding 7 to 17% water to the moving and circulating particulate detergent to raise the moisture content thereof to 19 to 25% whereby the moisture is substantially uniformly distributed throughout the mass of said particles and lightly compacting the resulting particles at a pressure of 3 to 25 p.s.i. into form retaining tablets of a bulk density between about 0.3 and 0.5 grams per cubic centimeter, said tablets being readily disintegrable in water, soluble therein and resistant to breakage when subjected to shipping shocks.

5. A process for manufacturing a detergent tablet which comprises making an aqueous mixture of a detergent composition comprising about 10% of nonyl phenol polyoxyethylene ethanol in which the polyoxyethylene ethanol averages about 9.5 oxyethylene units per molecule, about sodium tripolyphosphate, about 30% of sodium silicate of Na O:SiO ratio of about 1:2.35, about 7% of sodium sulfate and about 10% water, all percentages being on a final product basis except that for water, mixing the aqueous composition to distribute the various constituents thereof evenly, spraying the homogeneous mixture under pressure in fine droplet form into a drying gas and drying said droplets to particles substantially between 8 and 100 mesh and of bulk density of about 0.2 to 0.6 gram per cubic centimeter, moving and circulating a mass of said particulate detergent, adding about 12% water to the moving and circulating particulate detergent to raise the moisture content thereof to about 22% whereby the moisture is substantially uniformly distributed throughout the mass of said particles and lightly compacting the resulting particles at a pressure of 3-25 p.s.i. into form retaining tabletswhich are readily disintegrable in wash water, soluble therein and resistant to breakage when subjected to shipping shocks.

6. A detergent tablet which comprises 2 to 20% of a water-soluble synthetic organic detergent selected from the group consisting of sulfated and sulfonated anionic detergents and nonionic detergents containing hydrophilic and hydrophobic portions in the molecule of which at least the hydrophilic portion includes a plurality of lower joined alkylene oxide groups or mixtures thereof, 25 to 40% of a water soluble alkali metal polyphosphate, 20 to 50% of a water soluble alkali metal silicate, 3.5 to 10% of water soluble alkali metal sulfate and 17 to 30% water, the tablet being in the form of particles compacted at a pressure of 3-100 p.s.i., which tablet is disintegrable in wash water, soluble therein, form retaining and resistant to breakage when subjected to shipping shocks.

7. A detergent tablet which comprises 6 to 14% of a nonionic synthetic organic detergent which is a higher alkyl phenol poly lower alkoxy alkanol, 25 to 40% of a water soluble alkali metal tripolyphosphate, 20 to 40% of a water soluble alkali metal silicate of metal oxide to silica ratio between about 0.3 and 0.6, 3.5 to 10% of water soluble alkali metal sulfate and 17 to 30% water, the tablet being in the form of particles compacted at a pressure of 3-100 p.s.i., which tablet is of a bulk density between about 0.3 to 0.5 gram per cubic centimeter, form retaining and resistant to breakage when subjected to shipping shocks and also floats in wash water, disintegrates rapidly therein and is substantially completely soluble therein.

8. A detergent tablet which comprises 6 to 14% of a nonyl phenol polyoxyethylene ethanol in which the polyoxyethylene ethanol is of 9 to 10 oxyethylene units, 25 to 40% sodium tripolyphosphate, 20 to 40% sodium silicate of Na O:SiO ratio of about 0.4, 3.5 to 10% of sodium sulfate and 10 to 25% water, the tablet being in the form of spray dried particles compacted at a pressure of 3-100 p.s.i., which tablet is of a bulk density between about 0.3 and 0.5 gram per cubic centimeter, form retaining and resistant to breakage when subjected to shipping shocks and also floats in wash water, disintegrates rapidly therein and is substantially completely soluble therein.

9. A detergent tablet which comprises about 10% of nonyl phenol polyoxyethylene ethanol in which the polyoxyethylene ethanol averages about 9.5 oxyethylene units per molecule, about 30% of sodium tripolyphosphate, about 30% of sodium silicate of Na O:Si0 ratio of about 1:2.35, about 7% of sodium sulfate and about 22% Water, the tablet being in the form of spray dried particles compacted at a pressure of 3-100 p.s.i., which tablet is of a bulk density between about 0.3 and 0.5 gram per cubic centimeter, form retaining and resistant to breakage when subjected to shipping shocks and also floats in wash water, disintegrates rapidly therein and is substantially completely soluble therein.

References Cited by the Examiner UNITED STATES PATENTS 2,875,155 2/ 1959 Miles 252--138 3,081,267 3/1963 Laskey 252- FOREIGN PATENTS 510,555 3/1955 Canada.

JULIUS GREENWALD, Primary Examiner.

ALBERT T. MEYERS, Examiner.

Claims (1)

1. A PROCESS FOR MANUFACTURING A DETERGENT TABLET WHICH COMPRISES PRODUCING A PARTICULATE DETERGENT COMPOSITION COMPRISING 2 TO 20% OF A WATER-SOLUBLE SYNTHETIC ORGANIC DETERGENT SELECTED FROM THE GROUP CONSISTING OF SULFATED AND SULFONATED ANIONIC DETERGENTS AND WATER-SOLUBLE NONIONIC DETERGENTS CONTAINING BOTH HYDROPHILIC AND HYDROPHOBIC PORTIONS IN THE MOLECULE IN WHICH AT LEAST THE HYDROPHILIC PORTION INCLUDES A PLURALITY OF LOWER JOINED ALKYLENE OXIDE GROUPS OR MIXTURES THEREOF, 25 TO 40% OF A WATER-SOLUBLE ALKALI METAL POLYPHOSPHATE, 20 TO 50% OF A WATER-SOLUBLE ALKALI METAL SILICATE, 4 TO 12% OF A WATER-SOLUBLE ALKALI METAL SULFATE AND UP TO ABOUT 15% WATER, MOVING AND CIRCULATING A MASS OF SAID PARTICULATE DETERGENT, ADDING 2 TO 30% WATER TO THE MOVING AND CIRCULATING PARTICULATE DETERGENT TO RAISE THE MOISTURE CONTENT THEREOF TO 17 TO 30% WHEREBY THE MOISTURE IS SUBSTANTIALLY UNIFORMLY DISTRIBUTED THROUGHOUT THE MASS OF SAID PARTICLES AND LIGHTLY COMPACTING THE RESULTING PARTICLES AT A PRESSURE OF 3-100 P.S.I. INTO FORM RETAINING TABLETS WHICH ARE READILY DISINTEGRABLE IN WASH WATER, SOLUBLE THEREIN AND RESISTANT TO BREAKAGE WHEN SUBJECTED TO SHIPPING SHOCKS.