US3549541A - Enzyme carrying detergent particles - Google Patents

Description

X R 3 4 9 5 4 l. E X

I t O r 3,549,541 Ice Patented Dec. 22, 1970 water to steam and thus generating discrete small bubbles 3549 41 of gas. The tripolyphosphate produced by the reaction is,

ENZYME CARRYING DETERGENT PARTICLES Martin David Reinish, Emerson, N.J., assignor to Colgate- Ialmolive Company, New York, N.Y., a (orporation "of Delaware No Drawing. Filed May 31, 1968, Ser. No. 733,315 Int. Cl. Clld 3/065, 7/42, 11/00 US. Cl. 252-135 4 Claims ABSTRACT OF THE DISCLOSURE Spongeous pockmarked detergent particles carrying powdered enzyme preparation on their surfaces. The spongeous particles may be made by expanding an aqueous mixture of hydratable builder salt and detergent, setting the mixture and comminuting the set mixture.

This invention relates to particulate detergent compositions containing enzymes, which compositions are especially suitable for use in the washing of clothes, as in a washing machine of the automatic or nonautomatic type used in the home.

The preparation of detergent compositions comprising granules of detergent composition granules and powdered enzyme preparations is well known. As stated in the prior art, mechanical mixtures of the detergent granules and the enzyme powder tend to segregate, resulting in a nonuniform product, giving an undependable product which cannot be measured out accurately and which also prevents stability problems.

In accordance with one aspect of this invention, there is prepared a granular detergent composition comprising particles which are of substantially uniform ipockmarked spongeous structure containing spheroidal wa which particles are formed of irregularly shaped coherent aggregates of amorphous and crystalline material. including unoriented crystalline platelets, said particles carrying fine particles of enzyme preparation distributed thereon.

The particles of pockmarked spongeous structure may be produced by expanding an aqueous mixture of a hydratable builder salt and a detergent, setting the expanded mixture as by hydration of the builder saltyfid then breaking the set mixture into small particles. Illa expansion of the mixture may be efiected by bubbles of gas formed in situ.

In making the particles of pockmarked spongeous structure, one preferred method for forming the bubbles of gas in the mixture is of the use of an oxygen liberating compound, preferably hydrogen peroxide, which forms oxygen and water on" decomposition, providing effective bleaching and swelling. Another technique for forming the desired small gas bubbles is by subjecting a mixture of the aqueous detergent and a gas (e.g., nitrogen, oxygen, or carbon dioxide, and preferably air) to high shear, preferably under superatmospheric pressure, e.g., a pressure of about 20-50 p.s.i.g.

Instead of using an oxygen-liberating compound as previously described, one may use other methods for forming gas bubbles in situ. In one suitable technique, the gas is steam, the steam being generated by internal heating, as by the reaction'of an alkali metal trimethaphosphate with a base. In the latter reaction, the trimetaphosphate becomes a tripolyphosphate and a large amount of heat is evolved; this can raise the temperature of the aqueous blend to the boiling point, converting some of the free in turn, converted to hydrated crystals, thus removing freewater from the foamed mixture and helping to make it more viscous or solid.

Combinations of these methods may be employed in the manufacture of the particles of pockmarked spongeous structure. For example, in the use of high shear or of peroxygen compound, all or part of the tripolyphosphate content of the mixture may be generated in situ by reaction of trimetaphosphate and base. Also, a peroxidecontaining mixture may be subjected to high shear, if desired.

The builder salt used in the mixture is preferably one which forms a stable hydrate at room temperature. The most highly preferred inorganic salt is Form II pentasodiurn tripolyphosphate; however, other alkaline hydratable polyphosphates such as Form I pentasodium tripolyphosphate and tetrasodium pyrophosphate may also be employed. Likewise, if desired, sodium silicate, trisodium orthophosphate, sodium sulfate, sodium carbonate, s0- dium bicarbonate, or like alkaline and neutral detergent builder salts may be used in carrying out the process of the present invention. As previously indicated, the hydratable salt may be sodium trimetaphosphate which reacts with an aqueous base to yield sodium tripolyphosphate hexahydrate.

A suitable range of proportions of the inorganic salt is about 10 to about of the finished spongeous particles.

The water content of the mixture being foamed will depend on the particular foaming process. In the process in which the mixture is a pasty mass before foaming, the water content may be in the range of about 15 to 40%, preferably in the range of about 15 to 30%. Particularly good results have been obtained using pastes whose water contents were about 20 to"25% and whose solids contents were correspondingly about to 75 The amount'of water should be such that the mass is of such viscosity and fluidity that it can form a uniform paste having a consistency which permits it to swell or expand but which prevents rise of gas bubbles through the paste and therefore substantially preserves astructure of thoroughly dispersed fine gas bubbles, preventing substantial coalescence of the gas bubbles or loss offifls from the system.

The detergent employed in making the particles of pockmarked spongeous structure is preferably a water-soluble synthetic organic detergent which, in general, should have foaming properties. Examples are water-soluble salts of higher molecular weight sulfoxy-containing detergents such as a sulfonate or sulfate having a long hydrophobic chain (e.g., of 10-20 carbon atoms) such as a higher alkylbenze'ne sulfonate (e.g., dodecyl or tridecyl benzene sulfonate), a parafin sulfonate having for example about 10-20, preferably 15-20, carbon atoms such as the primary paraflin sulfonates made by reacting long chain alpha olefins and bisulfites (e.g., sodium bisulfite) or paraffin sulfonates having the sulfonate groups distributed along the paraflin chain such as the products made by reacting a long chain paiaflin with sulfur dioxide and oxygen under ultraviolet light followed by neutralization with NaOH or other suitable base (as in US. Pats. 2,503,280; 2,507,- 088; 3,260,741; 3,372,188 and German Pat. 735,096); an olefin sulfonate (made, for example, by reacting highly diluted gaseous S0, with an alpha-olefin followed by heating with alkali, and containing hydroxy alkanesulfonates and alkenyl sulfonates) or a fatty alcohol sulfate (e.g.,a

sulfate of a higher alkanol or a sulfate of an ethoxylated higher alkanol having 1-5, preferably about 3, oxyethylene groups per molecule). Other suitable synthetic anionic cb'tergents include water-soluble soaps of higher fatty acids such as the sodium soap of an 85:15 mixture of tallow and coconut oil fatty acids.

in addition to the anionic detergents, the organic detergent may constitute in whole or in part a synthetic noniqn'ic detergent such as nonionic detergents of the polyethylene oxide condensate type, e.g., the condensate of ethylene oxide with polypropylene glycol which condensate contains 80% ethylene oxide and has a molecular weight of about 1700, and iso-octyl phenoxy oolyoxyethylene ethanol having about 8.5 ethanoxy groups per molecule, and the like. Similarly, cationic and/or ampholytic detergents may be employed, in compatible amounts. Alkyl amine oxide detergents such as lauryl or myristyl dirriethyl amine oxides may be present. Mixtures of two or more detergents may be employed.

The total amount of the organic detergent is suitably in the range of about 265%, preferably about 10-40% of the final spongeous particles.

To facilitate handling when the mixture being foamed has a desirable low water content, all or a major portion of the water may be premixed with a portion of the solids and the remainder of the solids may be added, thus raising the viscosity of the blend, just before the foaming operation.

When the foaming step is accompanied by conversion of trimetaphosphate to hydrated tripolyphosphate, the mixture before foaming may be a slurry having a comparatively low viscosity, which viscosity increases considerably on the formation of substantial amount of the tripolyphosphate hydrate in situ during the foaming operation.

The hydrogen peroxide may be supplied as a commercial grade aqueous solution, e.g., of about 20-50% concentration and may contain a stabilizer. The amount employed may be, for example, in the range of about to 1% of H based on the total weight of the paste. Under the alkaline conditions (e.g., pH of about 9 /2 to 11) and the temperatures (e.g., about 35-60 C.) which are preferred in the mixing stage, hydrogen peroxide does not require the presence of any additional reactant but rather decomposes at a suitable steady rate effectively to bleach the detergent composition and to yield small, uniform bubbles of gas.

Oxygen yielding per-compounds other than hydrogen peroxide which may be employed in the instant process include the per-salts, such as, for example, sodium perborat'e, although in such a case it is usually necessary to use more vigorous conditions, e.g., a paste temperature of at least about 65 C., or the use of a decomposition catalyst, in order to achieve adequate liberation of oxygen while the paste is in a fluid or plastic condition conducive to expansion.

In the process in which the mixture is subjected to high shear, it is preferable to introduce compressed air into the paste and then subject the mixture under pressure to shear in a suitable mixer capable of imparting large quantities of energy and high shear rates to the mixture whereby the major proportion of the gaseous material is broken into discrete gaseous bodies having an average diameter on the order of less than about 0.085 millimeter and preferably less than about 0.054 millimeter.

Shear as used herein refers to an action resulting from applied forces which action causes contiguous portions ofthe mixture being treated to slide relative to each other. The forces applied to the mixture vary with the equipment used and the operating parameters of the process. By high shear" is meant an action of the type set forth immediately above, wherein there is a Shear Factor (F)" as defined below in excess of about 5 and preferably in excess of about 6.5.

wherein r=the radius of the mixer rotor in inches or its equivalent for a different type of mixing device;

R=the number of revolutions of the mixer rotor per minute or its equivalent;

T=the rate of feed of the material to be sheared in pounds per hour;

d=the clearance between the blades on the rotor and those on the stator or its equivalent; and

C=the volumetric capacity of the mixing device in cubic inches.

Suitable high shear mixers are generally relatively small in capacity so that at any particular moment only a small quantity of slurry is being worked upon, thereby allowing a major portion of the power input to be used directly on the slurry without becoming dissipated in an attempt to mix large quantities of material at one time. Thus, the mixer will advantageously have a capacity of less than about one gallon whereby material pan be passed through the mixer in less than about 30 seconds after being subjected to extremely high shear for this short period of time. The mixing device may be'of any suitable structure and, for example, may advantageously comprise a mixing chamber having two stators and a rotor adapted to rotate between the stators. The internal faces of both of the stators and both faces of the rotor may be provided with concentric rows of blades arranged so that the blades of the rotor mesh closely but out of contact with the blades of the stators. The slurry may advantageously pass from an inlet; at the center of one stator, between the blades of that stator and the rotor, across the rotor, and between the blades of the other stator and the rotor, and then to an exit at the far end of the mixer. In traversing this course through the mixing device the slurry and the gaseous material are torn, stretched, and cut by the blades into countless streams, and minute bodies of the gaseous material are evenly distributed throughout the slurry.

The foamed material is preferably discharged from the high shear mixer through a tube which serves also as a means for adjusting the pressure in the mixer. Thus, by increasing the length or decreasing the diameter of the discharge tube, the pressure in the mixer can be increased. It is desirable to use a pressure controlling member of this type instead of a throttle valve to avoid a sudden drop in pressure which may cause instability of the product. The length and diameter of the tube may be changed to maintain the mixer pressure within the range of about 20 to pounds per square inch gauge and preferably within about 50 to 65 pounds per square inch gauge. Advantageously, the length of the tube will be at least ten times the equivalent diameter thereof.

In generating foam by formation of steam in situ by reaction of trimetaphosphate and strong base, it is prefera'ble to use as the base an al 1 (preferably Na or K) hydroxide, c b I g r silicate (having a Slog/M30 ratio less-than were M is the alkali metal),

the amount of the base preferably being enough to convert at least half of the trimetaphosphate to the corresponding tripolyphosphate, more preferably (for complete conversion) at least about 2 equivalents (e.g., 2 to 6 equivalents) of strong base per mole of trimetaphosphateeIt is also preferable to heat the mixture either by supplying the precursor slurry at an elevated temperature (e.g., at above about 50 0., preferably above about 70 C.) before the strong base is added or to heat the mixture containing the base and the trimetaphosphate, so that the temperature of the mixture is raised eventually to about the boiling point.

It is generally desirable to mix the final foamable mixtute rapidly and to follow the mixing by a quiescent rests ing period in which a significant portion of the hydration of the salt takes place, without external agitation. The gas should expand the paste to the desired degree before hydration of the salt undesirably stitfens the paste, but mixing of the paste should not continue to the extent that a substantial loss of gas occurs. Thus, when hydrogen peroxide is employed in a continuous process, the ingredients are mixed together rapidly, almost instantaneously, the paste being expelled from the mixer into a receiver in less than about one minute, so that it may expand, cool and set in a quiescent stage.

In batchwise operation with hydrogen peroide, it has been found desirable to add the preferred pentasodium tripolyphosphate and hydrogen peroxide to the mixer as the last two constituents, and to add each of these two constituents to the ,reviously mixed components of the paste as quickly as possible. Mixing of the final paste is continued thereafter or 1y for the minimum period of time necessary to accomplish thorough mixing of all constituents. This may be less than one minute, and preferably is on the order of about 30 seconds. After discharge of its contents, it is unnecessary to clean the mixer as a new batch of material may be prepared therein in the presence of a heel of previously mixed materials (amounting to as much as 10% of the new batch) without requiring an increase in the amount of peroxide employed.

Similarly, in the high shear foaming process, the time after all of the components of the final product have been commingled and before the high shear mixing step is begun is suitably maintained at less than about five seconds. The throughput time in the high shear mixer will advantageously be less than about 30 seconds, and preferably between about and 20 seconds.

During the quiescent resting period, the foamed material may be stored in tubs, trays, or other receivers, or on a continuously moving belt. The mass attains a volume generally about 2 to 2V2 times the volume the material had before foaming, usually within a relatively short time, e.g., 15 minutes. Owing to the exothermic reactions, such as the hydration of the phosphate and the basemetaphosphate reaction, the mixture is generally at an elevated temperature during at least the first stages of the quiescent period; external heat may also be applied. The foamed material may be kept undisturbed until it has become rigid, and preferably until it has cooled to a temperature below about 30 C. (e.g., after about -48 hours when standing as an undivided mass, in air). Accelerated cooling may be used, and the mass may be subdivided, after it has rigidified in its expanded state, to promote cooling.

The expanded, friable detergent composition is then broken up, as by passage through a cage mill, manual crushing, or otherwise, and then preferably screened through a sieve, to give particles having diameters in the range of, for example, about 0.25-2 mm. (e.g. 0.4, 0.6 or 1 mm.).

The moisture content of the particles may be adjusted by placing them in a drying atmosphere, at room temperature, or in a drying oven; for this purpose, the particles may be suspended in a current of warm air or placed in a rotating drum through which hot air is passed.

The mixture may contain other ingredients which aid in processing or impart desirable properties to the final product, or to both. Among such ingredients are organic collodial materials with soil-suspending properties, hydrotropes, foam boosters, builders, fillers, and the like.

The organic colloidal material is preferably sodium carboxymethyl cellulose which serves not only as a soilsuspending agent during the washing of the clothes with the detergent product, but also has a desirable delaying efi'ect on the hydration of the tripolyphosphate and contributes to foam stability. Other colloidal water-soluble polymeric materials are polyvinyl alcohol and acidic vinyl polymers such as hydrolyzed ethylenemaleic anhydride or methyl vinyl ethermaleic anhydride copolymers or their alkali metal salts. The polymeric material may be present in the mixture in amounts in the range of about 0.1 to 1%, for example. The formulations used for making the particles of pockmarked spongeous structure may also include heat-sensitive constituents such as sodium perborate or amine oxides, e.g., a tertiary amine oxide detergent such as lauryl dimethylamine oxide, lauryl dihydroxyethyl amine oxide, or n-hexadecyl morpholine oxide. Melamine may be incorporated to inhibit the attack of washing solutions on copper and copper-bearing alloys. Optical brighteners, preservatives and the like may also be present in the compositions of the present invention in the amounts commonly used in detergent compositions.

In the particles of pockmarked spongeous structure, most of the voids have diameters not greater than about 0.2 mm. and substantially none of them have voids larger than 0.6 mm. The apparent density of the particles is generally less than about 0.45 gram per cubic centimeter, e.g., in the range of about 0.3 to 0.4 g./cc. The moisture content of the particles of pockmarked spongeous structure is generally in the range of about 15 to 35%, preferably (after some drying, if desired) about 15 to 25%.

Enzymes which aid in the removal of soil by detergent compositions are well known. Particularly useful enzymes for use in the instant invention are proteolytic enzymes which are active upon protein matter and catalyze digestion or degradation of such matter when present as in linen or fabric stain in a hydrolysis reaction. The enzymes are effective at a pH range of about 4-12, such as usually prevails in detergent cleaning procedures. Moreover, they may be effective even at moderately high temperatures so long as the temperature does not degrade them. Some proteolytic enzymes are effective at up to about C. and higher. They are also effective at ambient temperature and lower to about 10 C. Particular examples of proteolytic enzymes which may be used in the instant invention include pepsin, trypsin, chymotrypsin, papain, bromelin, colleginase, keratinase, carboxylase, amino peptidase, elastase, subtilisia and aspergillopepidase A and B. They are available also under names such as Alcalase (Novo lndustri, Copenhagen, Denmark), Monzyme (Monsanto Chemical Co.), Maxatase (Royal Netherlands Fermentation, Delft, Netherlands), Protease AP (Sandoz-Ferment, Basel, Switzerland), Protease B-400 (Sandoz-Perment), Protease ATP 40 (Sandoz-Ferment), Pancreatin NF (Pfizer), Pancreatin 6xNF (Armour), Fungal Protease (Miles), DSE Numbers 4-9 (Rohm and Haas), fixzyme DPX (Premier Malt), Protease L-252 Digester (Premier Malt), Protease L-253 Digester (Premier Malt), Protease L-423 (Premier Malt), Protease L-5l6 (Premier Malt), Protease L-517 (Premier Malt), Texzyme PX-l (Premier Malt), Protease P-G (Pfizer), Compound 37B (Miles), Serizyme (Wallerstein), Papain (Wallerstein), Optimo Papain (Penick), Ficin (Miles), Bromelain (Miles), HT Proteolytic Concentrate (Miles), Protease ATP 40 (Rapidase), Protease ATP (Rapidase), Rhozyme P-ll (Rohm and Haas) and Rhozyme PF (Rohm and Haas).

Proteolytic enzymes such as Alcalase, Maxatase, Protease AP, Protease ATP 40, Protease ATP 120, Protease L-252 and Protease L-423 are derived from strains of spore foaming bacillus, such as Bacillus subtilis.

Different proteolytic enzymes have different degrees of effectiveness in aiding in the removal of stains from textiles and linen. Particularly preferred as stain removing enzymes are Alcalase, Maxatase, Protease A'P, Protease ATP 40, and Rapidase.

Metalloproteases which contain divalent ions such as calcium, magnesium or zinc bound to their protein chains are also of interest.

- The amount of powdered enzyme preparation carried by the spongeous particles is usually in the range of about 0.1 to 3%, preferably about 0.2 to 0.8%.

The following examples illustrate the invention but are not to be construed as limiting it. In these examples, as elsewhere in this application, all proportions are by weight unless otherwise indicated. The term apparent density in these examples and elsewhere throughout the present specification and claims refers to the untampecl weight per unit volume of the particulate material as it is charged into a container.

EXAMPLE 1 Particles of pockmarked spongeous structure are made by mixing 610.1 parts of water and 288.5 parts of 50 B. aqueous caustic soda, followed by addition of 96 parts of sodiumtoluene sulfonate (containing 95% active ingredient, 2% water, 3% inert diluent) and 1115.9 parts of (branched ain) tridecyl benzene sulfonic acid (comprising 96% active ingredient, 2% sulfuric acid, 1% water and 1% byproducts of sulfonation), while the temperature of the mixture is maintained at below about 160 -F. After completion of the neutralization reaction, 440.2 parts of anhydrous sodium sulfate, 49.4 parts of a commercial powdered sodium carboxymethyl cellulose of 74% active ingredient (and a balance of water-soluble inert diluents), 4.6 parts of fluorescent dyes (optical brighteners), 15 parts of Ultramarine Blue and 0.2 part of Polar Brilliant Blue (conventional blue dyestuffs used for coloring detergent compositions) and 620.7 parts of aqueous sodium silicate (44.1% solids, in which the Na O:SiO ratio is l :2) are added while mixing continues to form a uniform slurry at l30l35 F. 1688.1 parts of pentasodium tripolyphosphate (anhydrous Form II) are then added and the blend is mixed rapidly for one minute, after which 78.5 parts of 35% aqueous hydrogen peroxide are added while high-speed mixing continues. One-half minute after the addition of H the resulting paste is discharged into an open vessel, where it is held for one-half hour in a hot room at a temperature of 140 F.; during this period, the paste expands to about two or more times its original volume. The expanded paste, after standing overnight at room temperature, is crumbled mechanically, roughly screened (through an EB-mesh screen having 2.38-mm. screen openings), dried in a fluid bed drier for minutes while heated air at a temperature of 140 F. is fed to the drier, then screened through a lO-mesh" screen (having 2 mm. screen openings) and finally screened over a 60 mesh screen (having 0.25-mm. screen openings) to remove fines. The particles have .t moisture content of 16.1%. The yield of the 0.25-2 mm. particles is 85%. The apparent density of the particles is 0.38 g./cc.

The particles are mixed with A of their weight of the proteolytic enzyme preparation known as Alcalase, which is a fine powder having its maximum proteolytic activity at a pH of 8-9. This activity as measured at pH 7.5 on the commercial enzyme preparation available from Novo Industri A/S, Copenhagen, Denmark is about 1.5 Anson Units per gram of the enzyme. The commercial enzyme preparation is a raw extract of Bacillus subtilis culture and contains about 6% of pure crystallized proteolytic material. Its particle size is such that a major proportion thereof passes through a 100- mesh screen (US. Standard, corresponding to a particle diameter of 0.15 mm.). Mixing may be carried out in any suitable apparatus such as a Twin Shell Blender, comprising a pair of coplanar circular cylindrical tubes intersecting at an angle of, say, about 75, joined together and mounted for rotation about a horizontal axis so that during rotation the intersection of the tubes moves in a circular path in a vertical plane; the material to be blended partially fills the tubes and mixing is effected by the rotation of llie device as described above. (Another suitable device .;is a conventional cement mixer, which comprises a hollow barrel mounted for rotation about an inclined axis.) The powdered enzyme preparation becomes distributed over the surface of the spongeous particles.

EXAMPLE 2 Spongeous particles prepared as follows: An olefin sulfonate is made by treating an alpha-olefinzSQ. reaction product with sulfuric acid under substantially nonhydrolyzing conditions, followed by alkalization with hot aqeous alkali, as described in the copending application of Rubinfeld and Ouw, Ser. No. 548,827 of May 10, 1966, now U.S. Pat. No. 3,428,654.

The olefin sulfonate is prepared by continuously reacting SO;, (14 lbs. per hour) and an alpha-olefin feedstock (40 lbs. per hour) in about 1:1 mole ratio, then treating the resulting mixture with aqueous H 50 (6 lbs. per hour) and then neutralizing with hot aqueous sodium hydroxide. The olefin feedstock used contains about 88% of terminally unsaturated straight chain olefins having an average molecular weight of 230 and an average chain length of about 15 to 18 carbons (C, 24%, C18-29%, C17-30%, c g17%, approximately) and has a boiling range at atmospheric pressure of about 265-300 C. (with 11% residue). The resulting syrup has a solids content of 41% and a content of anionically active material of 35%.

1629 parts of this syrup, 57 parts of water and 144 parts of 50 B. aqueous caustic soda are blended in a sigma blade mixer having a cooling jacket. 558 parts of a 96% tridecylbenzene sulfonic acid (containing 96% of the sulfonic acid, 2% free H SO 1% water and 1% of unsulfonated material) are then added to the stirred mixture while its temperature is maintained in the range of about -140 F. When the resulting neutralization of the alkylbenzene sulfonic acid is completed, 466 parts of sodium sulfate (anhydrous), 49 parts of a powder comprising the sodium carboxymethyl cellulose of 74% active ingredient, 4.6 parts of a fiubrescent dye and 332 parts of finely divided solid 82.5% sodium silicate (in which the Na O:SiO ratio i 1:2) are added while mixing continues, to form a uniform slurry at 114 F. 1688 parts of pentasodium tripolyphosphate (anhydrous Form II) are then added and the'blend is mixed at a rapid rate for one minute, after which 71.4 parts of 35% aqueous hydrogen peroxide are added while rapid mixing continues. One-half minute after the addition of the peroxide the resulting paste is discharged from the mixer into an open vessel where it is held, quiescent, for 15 minutes in a hot room having a temperature of F.; during this period the paste expands to 2-2 /2 times its original volume. The expanded paste, after standing overnight at room temperature, is crumbled mechanically and screened through a IO-mesh screen, having 2-mm. screen openings. The crumbled product, which constitutes the aforesaid spongeous particles, contains about 20.4% moisture, about 12% of the anionically active olefin sulfonate, and about 12% of sodium tridecylbenzene sulfonate.

The resulting particles (granules) are blended, as in Example 1, with 15% Alcalase powder; the product has the Alcalase powder distributed over its surfaces.

EXAMPLE 3 In this example the spongeous particles are manufactured by a process in which the expansion of the mixture is effected by steam bubbles generated by internal heating.

More particularly, the spongeous particles are made as follows: 329 parts of water, 231 parts of aqueous 50 B. caustic soda and 154 parts of sodium toluene sulfonate are mixed in a jacketed kettle. Then 895 parts of the sulfonic acid described in Example 1 are added and mixed, while cooling, until neutralization of the acid is complete.

197 parts of anhydrous sodium sulfate and 40 parts of commercial sodium carboxymethyl cellulose are then mixed in thoroughly, followed by 498 parts of the aqueous sodium silicate of Example 1, and then by a few parts of Polar Brilliant Blue (dispersed in a small amount of water). Then 1126 parts of sodium trimetaphosphate (Monsanto IF-61") are mixed in while the mixture is heated to a temperature of 140 F. 590 parts of 50 B. aqueous caustic soda are then added, with high speed mixing for one-half minute, immediately after which the mixture is discharged into an open vessel where it expands as steam is released from the reaction of the trimetaphosphate and caustic. After standing overnight the mixture is crumbled mechanically, and roughly screened through a screen having 2.38-mm. openings. '1 he resulting particles (granules) are blended, as in Example 1 with /z% of Alcalase powder; the product has the Alcalase powder distributed over its surfaces.

EXAMPLE 4 In another modification the proportion of enzyme preparation used in each of the above examples is increased to 2% and the enzyme-coated particles are blended with three times their vteight of a spray-dried heavy duty built detergent composition.

Altlough the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications can be substituted therefor without departing from the principles and true spirit of the invention. The Abstract" given above is for the conven ience of technical searchers and is not to be used for interpreting the scope of the invention or claims.

What is claimed is:

1. Solid particles of a detergent composition which particles have a bulk density of less than 0.45 gram per cubic centimeter and an average diameter of less than 2 millimeters, the particles being of a substantially uniform pockmarked spongeous structure containing spheroidal voids the majority of which voids have a diameter not greater than about 0.2 millimeter and substantially none of which is larger in diameter-than about 0.6 millimeter, said particles being formed of irregularly shaped coherent aggregates of amorphous and crystalline material including unoriented crystalline platelets, said composition consisting essentially of about 2 to by weight of a water soluble synthetic organic detergent selected from the group consisting of anionic and nonionic detergents, about 10 to by weight of an inorganic sodium salt selected from the group consisting of alkaline and neutral detergent builder salts which form a stable hydrate at room temperature, and about 15 to 35% by weight of moisture, said particles carrying on their surfaces about 0.1 to 3% by weight of a powdered proteolytic enzyme preparation, said particles being obtained by mechanically mixing a powdered enzyme preparation with the dry pockmarked spongeous particles.

2. A product as in claim 1 in which said spongeous particles have particle and have apparent densities of about 0.3 cubic centimeter.

3. Product as in claim 2 in which said proteolytic enzyme is active at a pH of 9.

4. Product as in claim 1 in which the powdered enzyme preparation constitutes about 0.1 to 1% of the product.

to 0.4 gram per References Cited UNITED STATES PATENTS 6/1969 Roald et al. 252-- 4/1965 Dugan 252-l35X US. Cl. X.R.

diameters of about 0.25 to 2 mm.