US3838072A - Manufacture of free flowing particulate detergent containing nonionic surface active compound - Google Patents

Abstract

PARTICULATE DETERGENT COMPOSITIONS WHICH ARE FREE-FLOWING AND NOT TACKY ARE MADE BY SPRAY DRYING AN AQUEOUS CRUTCHER MIX TO PRODUCE BASE DETERGENT BEADS CONTAINING SYNTHETIC ANIONIC ORGANIC DETERGENT AND SODIUM SILICATE, USUALLY WITH OTHER BUILDERS AND ADJUVANTS, AND SPRAYING OVER THE SURFACES OF THE BASE PARTICLES, WHILE IN MOTION, FROM ABOUT 2 TO 20% BY WEIGHT OF THE DETERGENT COMPOSITION OF DROPLETS OF A HIGHER LINEAR ALKOXY POLY-LOWER ALKOXY LOWER ALKANOL NONIONIC COMPOUND IN WHICH THE POLY-LOWER ALKOXY LOWER ALKANOL CONTENT OF THE NONIONIC COMPOUND IS FROM 39 TO 60% BY WEIGHT. THE NONIONIC COMPOUND, WHICH HAS SURFACE ACTIVE PROPERTIES, IS USUALLY APPLIED AS A WARM OR HOT LIQUID ONTO FRESHLY SPRAYED AND STILL WARM OR HOT DETERGENT BEADS. PREFERABLY, THE NONIONIC COMPOUND IS SPRAYED ONTO THE BASE BEADS TOGETHER WITH A NONIONIC DETERGENT WHICH IT AIDS IN PENETRATING INTO THE BEAD, THEREBY IMPROVING PRODUCT FLOW CHARACTERISTICS AND DIMINISHING TACKINESS.

Description

MANUFACTURE OF FREE FLOWING PARTICULATE DETERGENT CONTAINING NONIONIC SURFACE ACTIVE COMPOUND Filed March l5, 1971 2 Sheets-Sheet l Sept. 24, 1974 F. R. SMITH, JR., ETAL 35,38,072

MANUFACTURE OF FREE FLOWING PARTICULATE DETERGENT CONTAINING NONIONIC SURFACE ACTIVE COIPOUND Filed March 15, 1971 2 Sheets-She et m a on United States Patent 01 ffice N.J., assignors to Colgate-Palmolive Company, New York, N.Y.

Filed Mar. 15, 1971, Ser. No. 124,111 Int. Cl. C11d 1/22, 1/83, 11/00 US. Cl. 252-540 16 Claims ABSTRACT OF THE DISCLOSURE Particulate detergent compositions which are free-fiowing and not tacky are made by spray drying an aqueous crutcher mix to produce base detergent beads containing synthetic anionic organic detergent and sodium silicate, usually with other builders and adjuvants, and spraying over the surfaces of the base particles, while in motion, from about 2 to 20% by weight of the detergent composition of droplets of a higher linear alkoxy poly-lower alkoxy lower alkanol nonionic compound in which the poly-lower alkoxy lower alkanol content of the nonionic compound is from 39 to 60% by weight. The nonionic compound, which has surface active properties, is usually applied as a Warm or hot liquid onto freshly sprayed and still warm or hot detergent base beads. Preferably, the nonionic compound is sprayed onto the base beads together with a nonionic detergent which it aids in penetrating into the bead, thereby improving product fiow characteristics and diminishing tackiness.

This invention relates to the manufacture of particulate synthetic organic detergent compositions. More particularly, it is of methods for making such compositions having improved detergency by overspraying certain nonionic surface active compounds or mixtures thereof with similar nonionic detergents onto globular detergent base particles, such as those which may be made by conventional spray drying methods.

In accordance with the present invention a method of preparing a particulate detergent composition comprises making particles of a base detergent composition containing synthetic organic detergent and inorganic salt, which salt includes sodium silicate, and distributing over the surfaces of the particles, while they are in motion, from 2 to 20% by weight of the final composition, of a higher alkoxy poly-lower alkoxy lower alkanol nonionic compound, wherein the poly-lower alkoxy lower alkanol content of the nonionic compound is from about 39 to 60% by weight.

In most embodiments of the invention, the synthetic organic detergent f the base detergent composition is anionic, e.g., linear higher alkyl benzene sulfonate, the inorganic salt is one which can act as a builder for the anionic detergent and may include sodium carbonate, sodium bicarbonate or sodium sesquicarbonate to aid in the sorption of the nonionic compound and to improve the flow and non-tacky characteristics of the product. Also, the amounts of synthetic detergent, moisture, synthetic organic gum anti-redeposition agent, sodium silicate, sodium sulfate and pentasodium tripolyphosphate in the detergent base will be limited, the base will be spray dried and the nonionic compound will be sprayed as a liquid onto the surfaces of the spray dried particles while they are in tumbling motion at a time shortly after the completion of spray drying. Also, it is preferred for the nonionic compound to have a nonionic detergent mixed with it or applied to the detergent beads at the same time. The invention also relates to particulate detergent compositions,

3,838,072 Patented Sept. 24, 1974 such as those which can be made by the methods of the invention.

By the present method there may be added to detergent compositions liquid or near liquid nonionic surface active materials which improve the washing or soil-removing properties of the compositions and still allow them to remain free flowing and of acceptable non-tacky properties. When the detergent particles are of relatively light weight, e.g., 0.3-0.6 g./cc. bulk density, and readily soluble hollow globular form, such as are produced by spray drying, substantial improvements are made in the production method over processes wherein nonionic surface active and/or detersive compounds are present in the crutcher mix and are sprayed dried with the other ingredients. In such spray drying operations the nonionics tend to plume and often are lost from the spray dryer as fine aerosols, causing air pollution, as well as other economic losses, and changes in the contents of such materials in the final products. Using the present method, greater throughput is obtainable for the spray drying towers and greater flexibility in formulating may be realized. Also, the proportions of nonionic surface active and detergent materials in detergent compositions may be increased beyond those normally obtainable from the spray drying process and surprisingly enough, the product resulting is often of improved appearance.

Various compositions, methods, operations, constructions, conditions, details, uses and advantages of the invention will be apparent from the following description, taken in conjunction with the illustrative drawing of a preferred embodiment thereof, in which drawing:

FIG. 1 is a schematic flow diagram showing the manufacture of an oversprayed spray dried detergent;

FIG. 2 is an enlarged partially sectional side elevation of tumbling apparatus employed in the practice of the invention, showing locations where additions of various detergent composition components may be made; and

FIG. 3 is a partially sectional end elevation of the apparatus of FIG. 2.

In FIG. 1, aqueous detergent base crutcher mix 11 is agitated in crutcher 13 by stirring means 15 which maintains it in substantially homogeneous condition. Heating means, not shown, are usually employed to raise and regulate the crutcher mix temperature so as to increase the solubilities or dispersibilities of the detergent components and to diminish the mix viscosity, so as to facilitate spraying. A high pressure pump 17, capable of producing pressures of 200 to 2,000 lbs./ sq. in., pumps the crutcher mix through line 19 and spray nozzles 21 when valve 23 is opened. In spray tower 25 the sprayed droplets 27 of crutcher mix pass downwardly through an upwardly moving stream of heated air generated by burner 29, which air passes into the spray tower 25 through duct 31 and inlet ring 33. As illustrated, the heated air or combustion products result from burning oil passed through nozzle 35 with air supplied by blower 37. A vacuum is drawn on the spray tower by blower 39 and the spent drying air is removed from the tower through duct 41 and cyclone separator 43, which removes fine particles from the air at 45, allowing the cleaned air to be vented at outlet 47, after having passed through blower 39. Additional air cleaning means, such as bag-type dust separators, may also be used in conjunction with the cyclone separator but are not illustrated herein.

The dried detergent particles 49, usually in hollow globular or bead form, are removed from the spray drying tower by gravity and air lift 51, which is operated by vacuum generated by blower 53, and the particles travel past baffle 55 to hopper 57 for bin 58, from which they are ready to be fed to a tumbling apparatus for post spraying to make the product of this invention.

The various parts of the overspraying apparatus next described are better illustrated in enlarged FIGS. 2 and 3 than in FIG. 1. Belt feeder 59 carries spray dried base beads 49 from bin 58 under hopper 57 through hopper 61 and passage 63 into continuous tumbling drum 65. Instead of utilizing the continuously rotating drum illustrated, other continuously moving tumblers, such as twin shell blenders, may be employed. Such other tumblers or the present drum, if suitably modified, may be utilized in batch operations. In the preferred continuous operation, any other adjuvants which it may be desirable to add before or at the early stages of tumbling may be fed from bin 67 by feed belt 69 through line 71 to drum 65. Materials desirably added at this time include anti-redeposition agents, such as sodium carboxymethyl cellulose, extra sodium silicate and sometimes, additional sodium tripolyphosphate. In enzyme-containing detergents, the enzymes may be added at such points or farther down the tumbling drum.

Perfume and/or any other liquid additives which are insufiiciently stable to be spray dried or which for any other reasons are desirably added after spray drying, may be forced onto the base beads through line 73 and out spray nozzle 75 or through other similar lines and nozzles. Usually slightly farther down stream than the perfume addition nozzle, the nonionic surface active compound overspray material, which may be in a common solution with nonionic detergent, is similarly passed through line 77 and nozzles 79. As illustrated, three such spray nozzles are shown, each of which is separated from the next adjacent nozzle by from one to two feet. Separations may be varied, depending on the sizes of the drums, and can be from three inches to three feet. The number of nozzles may be modified for the particular tumbling drum but usually will be from one to six. After a sufiicientresidence time in the tumbling drum, preferably in continuous operation, the treated detergent particles 81 may have other powdered additives mixed with them, usually to improve flow and reduce tackiness. Thus, a finely divided clay, talc or other suitable lubricant or flow-inducing agent, such as calcined aluminum silicate (Satintone), may be added to the tumbling drum near the downstream end thereof by feeding it from bin 83 through screw feeder 85, hopper 87 and line 89. The various screw feeds, belt feeds and pumping rates for the liquids to be sprayed are regulatable individually or may be controlled by a proportioning mechanism, not shown, which maintains the desired balances of the various materials to be charged. Thus, the entire operation may be automated.

After production of the oversprayed detergent particles 81 and dusting thereonto of flow-inducing powder or other suitable finely divided materials, the product is removed through exit 91 and forms a bed 93 on vibratory feeder 95. This bed of material is transported by the feeder to hopper 97 past screen 99 to filling bin 101, from which it is discharged to packages 103 passing along belt 104 under filling head 105. The packages are then automatically closed, sealed, cased and shipped. Any oversize particles failing to pass through screen 99 are discharged at takeoff 100. These and other oversized and undersized particles may be re-worked or otherwise further processed to be made suitable for blending with the rest of the oversprayed detergent particles produced.

Although it is not intended to elfect substantial evaporation of moisture or other volatiles in the tumbling drum 65, a slight flow of air through the drum is maintained by applying vacuum to the downstream end thereof, as illustrated by vacuum hood 107. The hood is so formed as to exert a slight effect on bed 93 of oversprayed particles and through the bed to cause an air flow from the upstream to the downstream end of the tumbling drum. Thus, any very finely divided mist-like droplets of liquid to be oversprayed onto the detergent particles will be drawn by the vacuum through the bed 93 and deposited on the particles, if this is not completely effected in the tumbling drum. Colloidal liquid not so deposited and very finely divided solid particles are removed via line 109.

FIG. 3 shows the relative positioning of the various lines for the addition of detergent base particles, sodium carboxymethyl cellulose or other resinous or gum anti-redeposition agents or other particulate additives, overspraying nonionic surface active agent or mixture thereof with nonionic detergent, and perfume or other liquid additives. It will be noted that nozzles 75 and 79 are so directed as to spray the liquids onto the moving particles 49, which action avoids production of large quantities of tailings due to overconcentrations of the liquids on apparatus walls or on any relatively quiescent materials near the points of spraying. Arrow 111 indicates the direction of rotation of the tumbling drum.

In making the base detergent composition it is highly preferred to employ a spray dryer, either countercurrent or concurrent, such as are known in the detergent industry to be useful for the production of light weight and substantially globular detergent beads, which preferably are also hollow. Other apparatuses may be used providing that the base particles produced are of desired particle size, shape, density and flow characteristics. However, it is not desirable to use agglomerated particles, made by mere mixing of finely powdered detergent composition constituents in the presence of a binding agent, nor is it preferred to employ dry mixtures of ground detergent composition ingredients.

Spray drying is effected by crutching an aqueous crutcher mix of the base detergent composition, which may be essentially inorganic salt but generally should include a synethic organic detergent, preferably an anionic detergent, which term includes the usual higher fatty soaps. Of the anionic detergents the higher alkyl benzene sulfonates, especially the water soluble salts of linear higher alkyl benzene sulfonates, e.g., the alkali metal salts, of which sodium linear higher alkyl benzene sulfonate is preferred, will be employed. However, other anionic detergents and minor proportions of nonionic detergents, providing that they do not cause pluming in the spray tower, may also be present. Such compounds are well known in the detergent art and are described at length at pages 25 to 138 of the text Surface Active Agents and Detergents, Vol. II, by Schwartz, Perry and Berch, published in 1958 by Interscience Publishers, Inc. Among the important anionic compounds so listed are the higher alkyl sulfates, the higher fatty acid monoglyceride sulfates, the higher olefin sulfonates, the higher alkyl sulfonates, the sulfated phenoxy polyoxyethanols, the branched higher alkyl benzene sulfonates and the higher fatty acid soaps. Usually, such compounds or derivatives are employed as water soluble salts and generally these are alkali metal salts, e.g., sodium salts, of the mentioned compounds. Also, the higher alkyl or fatty groups will generally be of 12 to 18 carbon atoms. Of the nonionic detergents, those are preferred which are hydroxyl-containing linear polymers of lower alkylene oxides and are normally liquid or semi-solid at room temperature. These include condensation products of higher fatty alcohols with polyoxy-lower alkylene glycols, such as Neodol 45-l1, Plurafac B-26 and Alfonic 1618-65. Also useful are the block copolymers of propylene glycol, propylene oxide and ethylene oxide, such as the Pluronics, e.g., Pluronic L-44, and the middle alkyl phenyl polyoxyethylene ethanols, such as those sold as Igepals. Most of these compounds are not as good in the present detergent products as the anionics because they tend to plume objectionably when spray dried, and can cause environmental mist problems when present in larger proportions in the base product. Therefore they will be present in minor proportions, which will generally be less than half the content of the organic detergent component of the base.

The linear higher alkyl benzene sulfonates will normally be of 12 to 15 carbon atoms in the alkyl groups, preferably of 13 or about 13 carbon atoms and the linear alkyl will be substantially terminally joined to the phenyl group. However, a minor proportion thereof may be joined to the 2- or 3-carbon but generally the amount thereof will be less than 30% and most of that will be joined on the 2-carbon. Although small quantities of such soluble sulfonates of metals other than sodium may be present, such metals normally will be minor proportions of the salt-forming metal. It will usually be preferred to employ the sodium higher linear alkyl benzene sulfonate as the sole anionic detergent constituent of the base beads, since it is a good and acceptably biodegradable detergent, but it may sometimes be desirable to mix it with other anionics for specific purposes. For example, small proportions of soap e.g., the sodium salt of an 80:20 or 85:15 tallow-coconut oil fatty acids mixture, may be present.

The greater part of the solids content of the crutcher mix is of inorganic salts, principally as builders or fillers for the detergent. An important builder salt constituent of this type is sodium silicate, although other alkali metal silicates may also be used. Of the sodium silicates which are employed, those having an N21 0:SiO ratio of from 1:1.6 to 1:3.4 are generally useful, either as the entire silicate content or a part thereof. Silicates of Na O:Si0 ratio of 1:2 to 1:3 are preferred and of them those of ratios of 1:2 to 1:25, specifically 1:2.3, are presently most preferred, although 1:2 silicates may be most used in the future. These silicates have building properties, add desired alkalinity, are anti-corrosive and are suitable for producing good crutcher mixes and stronger detergent beads. Other useful builders include pentasodium tripolyphosphate and tetrasodium pyrophosphate. Trisodium nitrilotriacetate is a good builder, if environmentally acceptable, but its content should be minor because of a tendency to counter sorption of the nonionic overspray. Additional compounds which serve as builders, usually most effective in the absence of phosphates, are borax, sodium carbonate, sodium bicarbonate and sodium sesquicarbonate. A good filler salt is anhydrous sodium sulfate and sodium chloride may sometimes also be employed.

Various other constituents and adiuvants may be present in the crutcher mix or may be post-added, including sanitizers, e.g., trichlorocarbanilide, coloring agents, e.g., dyes and pigments, foam improvers, foam depressants, fungicides, antioxidants, stabilizers, chelating agents, optical bleaches or fluorescent brighteners, soil suspending agents and soil antiredeposition agents. Of the foregoing adjuvants those of most importance to the present invention, especially with respect to ready operativeness of the method and unexpected improvements in the products, are the anti-redeposition agents and the fluorescent brighteners. The anti-redeposition agents include natural and synthetic organic gums or resinous materials which aid in maintaining the removed soil and other constituents of a detergent wash water in suspension so that they are not deposited on the laundry as the rinse water is drained through it. Such compounds include sodium carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl alcohol and similar agents known in the art. The fluorescent brighteners are members of a well-known class in the detergent art and usually are reaction products of cyanuric chloride and the disodium salt of diamino stilbene disulfonic acid, benzidine sulfone disulfonic acid, amino coumarins, diphenyl pyrazoline derivatives or naphthotriazolyl stilbenes. Such materials are described in the article Optical Brighteners and Their Evaluation by Per S. Stensby, a reprint of articles published in Soap and Chemical Specialties in April, May, July, August and September, 1967, especially at pages 3-5 thereof. They include cotton brighteners, polyamide brighteners, polyester brighteners and bleach-stable brighteners of the types mentioned, such as those sold as Stilbene No. 4, Calcofluor White ALF (American Cyanamid), SOF (Ciba), Blancophor PD (GAF) and Tinopal RBS (Geigy). These are of complex structures. For example,

6 the formula of Stilbene No. 4 is disodium 4,4'-bis-(4- anilino 6 morpholine-s-triazin-2-ylamino)-2,2-stilbene disulfonate. Yet, despite the complexities of their structures and their differences, the brighteners act to whiten the detergent particles made according to this invention.

The proportions of the various components in the crutcher mix from which the spray dried bead is produced are regulated so as to obtain a bead on which the nonionic surface active or detergent overspray may be deposited and in which it will be sorbed without causing the production of sticky, tacky or poorly flowing beads. The crutcher mix will usually comprise from 25 to 75% solids, preferably from 50 to 70%, with the balance being mostly, almost entirely or only water. The proportions of various crutcher mix constituents will be such as to result in a detergent product having the composition given below. Percentages of constituents calculated on a detergent product basis are considered to be more convenient to use than percentages based on either the crutcher mix or the spray dried base beads, which would require recalculations to determine concentrations in the product. Of course, the product can be re-formulated with other materials to make still more end or final detergent products. Thus, colored detergent or inorganic salt particles may be blended in with the product to produce a dotted effect or the product can be diluted with filler particles to produce detergents of varying active ingredient concentrations.

The quantity of silicate employed should generally be from 5 to 35%, about 5 to 15% being acceptable in the crutcher with the remainder being post-added. 12% is a preferred limit, and 10% is most useful in the spray dried base. At up to 15% concentration in the spray dried base beads the silicate exerts a significant building effect and strengthens the bead but does not inhibit the sorption of the nonionic surfactant or detergent of the overspray so as to produce a poorly flowing or tacky product. Use of more than about 15% of the sodium silicate in the crutcher mix causes a significant lumping of the base beads and a decrease in flowability of the oversprayed particles and therefore, is to be avoided. When other constituents which have negative effects on flowability or non-tacky properties of the product are also present, the proportion of sodium silicate will usually be decreased further, as to 10%. Below 5% content thereof its building properties and contribution to increased particle strength are not substantial.

For excellent cleaning properties in these compositions it is often desirable to utilize pentasodium tripolyphosphate or, in some cases, tetrasodium pyrophosphate, with the former being much preferred. Generally, the totals of such phosphates will be within the range of 10 to 40% or 20 to 35%, for good detergency and acceptable flow properties. It is preferred that such content be almost entirely or all sodium tripolyphosphate. In formulations wherein superior detergency is not vital or when it is desired to minimize the content of phosphates or to omit them, substitute builder materials may be utilized and in some cases, such materials will be present together with the phosphate, for their supplementary activities. Thus, when sodium tripolyphosphate content is reduced to 10 to 30%, or omitted, increased amounts of sodium silicate, within the range given previously, will preferably be utilized and sodium carbonate, sodium sesquicarbonate or sodium bicarbonate, preferably the first, will be present to compensate at least in part for the effects of decreasing the phosphate content. In such cases and even when the phosphate is present in full proportion, the amount of carbonate present may be from 5 to 35% and is preferably in the 5 to 20% range when phosphate is present. The carbonate used is preferably entirely sodium carbonate. Another builder or supplementing salt which may be used is borax and the proportion thereof present will usually be from 5 to 25%, preferably from 5 to 15%. NTA may be present in some compositions but, to comply with Government recommendations, will usually be omitted. Fillers or extenders present may include up to 40% sodium sulfate, preferably to 40% and frequently from 15 to 30%, and up to 15% sodium chloride, usually less than 8% thereof. In the presence of substantial amounts of phosphate the borax, carbonate, bicarbonate and sesquicarbonate builder may not contribute much additional building effect (phosphates are so effective as to overshadow other builders), but they are still referred to herein as builders.

The synthetic organic detergent component will usually be from 5 to 15 of the mentioned sodium linear alkyl benzene sulfonate and should generally not exceed 20% thereof nor be less than 5% to have any significant detersive effect. Other anionic or nonionic detergents may be used in supplementation of or in partial replacement of the linear alkyl benzene sulfonate but usually such total other synthetic organic detergent content will not exceed the amount of the sodium alkyl benzene sulfonate present. Generally, the amounts of such supplementing detergents, if present, will be less than e.g., from 0.1 to 5% of soap, from 2 to 5% of sodium higher alkyl sulfate, and from 0.1 or 1 to 2% of nonionic, if present.

The various adjuvants in the base beads which supplement the action of the organic detergents and inorganic salts will normally be limited to about of the product and generally will be less than 10% thereof. The contents of anti-redeposition agent, e.g., sodium carboxymethyl cellulose, will be held as low as feasible in the crutcher since this material acts to counter sorption of the nonionic overspray. Generally the maximum proportion of such anti-redeposition agent in the base beads will be in the range of about 0.5 to 1%, preferably about .5%. When greater quantities of sodium carboxymethyl cellulose or similar anti-redeposition agent are desired to be present, they may be added to the tumbling drum in proportions up to 5% since it has been found that such addition does not act against sorption of the overspray. It is preferable that all the CMC be tumbled into the detergent formulation. The fluorescent dye content will usually be from 0.05 to 1%. The bleach content, if sodium perborate is employed as the bleach, will be from 1 to 30%, with some or all being post-added. Various other constituents will normally not exceed 2% and preferably will be held to 1% each, if present. The moisture content of the spray dried base beads will be from 1 to 15 preferably from 3 to 15 and most often from 7 to 13%. Such will also approximate the moisture contents of the detergent made.

After the manufacture of the spray dried base beads, which will be described in detail subsequently, they have distributed over the surfaces thereof the nonionic surface active compound which improves their washing action. Applications of liquid nonionic detergents to granular mixes of organic detergent and inorganic builder and filler salts have been effected in the past. However, the amounts of liquid nonionics employed usually had to be low, often under 1% or 0.5%, which small amounts will alleviate dusting problems and do not cause undue lumping or tackiness of the product. It has now been found that, in accordance with this invention from 2 to preferably 2 to 15 and most preferably about 3 to 10% of a higher linear alkoxy poly-lower alkoxy lower alkanol nonionic compound, wherein the poly-lower alkoxy lower alkanol content is from 39 to 60% by weight of the compound, can be applied to the detergent base beads described to improve their cleaning properties without causing lumping, poor flow or tackiness. The higher linear alkoxy is preferably of 10 to 18 or 10 to 16 carbon atoms, most preferably 12 to 15 carbon atoms and the poly-lower alkoxy lower alkanol is one in which the lower alkoxy and alkanol are of 2 to 3 carbon atoms each and the total of carbon atoms in the poly-lower alkoxy lower alkanol, which is preferably polyethoxy ethanol, is from 6 to 15, preferably 6 to 14. The nonionic surface active agent mentioned is utilized for its stain-removing action and appears to improve the washing action of the total bead and produces a product which is free flowing and non-tacky, even at the increased concentrations often employed. In the selection of such compounds it is desirable to utilize those which are of a sufiiciently low viscosity, like that of water at room temperature, at the temperature of application, 10 to 65 C., preferably 25 to 55 C. Generally such materials are applied as active liquids but they may have some water present, which should normally be limited to 5% of the surface active agent, as applied, preferably less than 1%.

It has been discovered that the use of the mentioned nonionic surface active agents as an overspray allows the mixing therewith of similar or related nonionic detergents, usually having longer higher alkoxy and polylower alkoxy alkanol chains. Such compounds have detergent properties when the higher linear alkoxy is of 12 to 18, preferably 13 to 16 carbon atoms and the poly-lower alkoxy lower alkanol theerof is of 20 to 30 carbon atoms. Preferably, the higher alkoxy i of 14 to 15 carbon atoms and the poly-lower alkoxy lower alkanol is of about 22 carbon atoms for the detergents. Such compounds are commercially available from Shell Chemical Company under the names Neodol 253 or 25-7 (surface active) or Neodol 45-11 (detergent). The proportion of nonionic surface active agent or solvent or nonionic detergent of the types mentioned will normally be from 1:2 to 4:1 and the total of such compounds present will generally be from 4 to 15% of the final particulate detergent composition, preferably from 6 to 12% theerof, if the detergent is present. In this specification the term surface active is used to distinguish the described lesser alkoxylated nonionic surface active solvent or non-detergent compounds from the higher alkoxylated detergents. It is recognized that detergents are surface active too and that some of the lesser alkoxylated materials such as Neodol 25-7 possess some detergent properties but for convenience of description the given nomenclature has been adopted.

In addition to the alkoxy polyalkoxy alkanol surface active compounds described, it has been found that similar useful washing effects and penetrating properties are obtainable by utilization of di-alkyl phthalates, especially the di-lower compounds or derivatives thereof, such as dibutyl phthalate. Although such a compound can be employed in total replacement of the nonionic surface active agent, for best effect it should replace only a part thereof, if any. Thus, the dibutyl phthalate will normally not be more than a minor proportion of the total overspray surface active material, excluding the detergent, and will usually be within the 10 to 40% replacement range, if utilized. It has also been discovered that other poly-lower alkoxy lower alkanol-containing materials may be employed as the nonionic constituents, especially as the nonionic detergent. For example, middle alkyl phenoxy polyethoxy ethanol detergents wherein the middle alkyl is of 7 to 10 carbon atoms and the polyethoxy ethanol is of chain length comparable to the nonionic detergents previously described, may be substituted for them either in whole or in part. Penetration into the beads will be aided by the presence of such surface active agent and tackiness and poor flow of the beads will be prevented.

With the application of the overspray nonionic materials it will sometimes be desirable for other constituents of the final product to be added during the tumbling operation. Usually the most important of these is the anti-redeposition agent and from 0.3 to 5% of such agent, usually sodium carboxymethyl cellulose, will often be blended in with the base detergent beads before spraying onto them of perfume and the overspray nonionics. However, in some formulations no organic anti-redeposition agent is needed. Stain-removing enzyme can be added at same locations as the CMC to the extent of about 0.05

to 1%, to improve the stain removing properties of the product. They will usually be in the form of sphere prills. The perfume content, generally from 0.1 to 0.05% of the product, will usually be sprayed onto the tumbling or otherwise moving detergent base beads before spraying thereonto of the overspray nonionic. If desired, to further promote whitening of the surfaces of the particles, the fluorescent dye may be applied in the overspray.

When considered to be advantageous, proportions of other constituents may be applied in manner similar to that in which sodium carboxymethyl cellulose may be added. In such cases, corresponding amounts of such materials can be removed from the base formula. Such additions are especially desirable when the materials to be added in the tumbler are of substances which, in the spray dried or homogeneous detergent beads, inhibit penetration of the overspray into the beads, as do CMC and excess anionic detergent. For example, portions of sodium silicate and sodium sulfate may be added in the tumbler, rather than in the crutcher mix, to permit more ready processing of formulations containing larger amounts of these materials than would otherwise be desirable. On the other hand, sodium carbonate will usually not be post-added because it adds penetration of nonionic overspray into the interior of the base beads if it is in the bead formula. The post-added solid material in excess of 5% should preferably be granular (of particular size like that of the base bead). However the CMC should usually be added as a finely divided powder.

The oversprayed particulate detergent produced according to the foregoing formula and general procedure will be free flowing and does not tend to cake objectionably on storage. Thus, when at a density of about 0.3 to 0.6 grams/cu. cm., packed in cardboard detergent cartons, it pours easily despite storage at ordinary temperatures in humid atmospheres. Such a detergent box need usually only be tilted slightly to allow pouring of the contents as they are being measured for addition to a washing machine. For further insurance of excellent flow properties, however, it may sometimes be desirable to add from 0.2 to 3% of a very finely divided flow improving clay for such purposes, such as calcined aluminum silicate, sold as Satintone. Such additions will preferably be at a point near the outlet from the tumbling drum or will be effected near the end of the tumbling or mixing operation, after addition of the overspray liquid. This is done so that the clay will not be worked into the body of the detergent head but will remain thinly spread out over the surfaces thereof to promote easy slip and free flow. For best effects, the clay shouldw be sufficiently finely divided so as to pass substantially entirely (99% or more) through a 325 mesh sieve. Other ingredients, including salts and CMC, etc., can be added at either end of the mixer or intermediately but preferably are added upstream, with only Satintone being added at the downstream end.

Production of the homogeneous base may be by any suitable well-kown method employed in the art. In spray drying operations, whether countercurrent or concurrent towers are employed, the general operation will be as outlined in the figures of the accompanying drawing. The crutcher mix will be heated to a temperature of about 60 to 90 C. and will be sprayed through spray drying nozzles at a pressure of 200 to 2,000 lbs/sq. in. to globular droplets which will pass through drying gas, usually at a temperature of 150 to 300 C., and will have their moisture content reduced to 15% or less. The dried particles resulting, which may be at to 65 C. but are usually at 27 to 43 C., will largely be in the 6 to 200 or 6 to 100 mesh particle size range but may be screened to remove tailings. Preferably, the particles will be produced in the 8 to 100 mesh range, U.S. Standard Sieve Series.

When spray dried detergent particles are fresh and warm, having been spray dried within the half hour, often Within five minutes or less and being at a temperature of from 27 to 43 C., they will often be sufficiently soft so that upon addition of liquid materials they will be expected to agglomerate and become tacky. It is a feature of the present invention that, utilizing the homogeneous and preferably hollow globular detergent base beads with the particular nonionic surface active agents described, overspraying is possible on fresh warm base particles wthout objectionable agglomeration. Thus, special cooling and/or storage of the spray dried base particles are not necessary and efficiency of the manufacturing operation can be raised substantially. In fact, it is preferred to use fresh Warm base particles, usually within 30 minutes to an hour after making and sometimes within five minutes or less. Rather than producing tacky or poorly flowing product as might have been expected, the fresh warm particles are usually even more sorptive than aged particles (several hours or a day old) and the product is better. The minor amount of agglomeration which may occur during practice of the present invention is not objectionable because the large particles readily break up in a screaming operation. After screening, the particle sizes are in substantially the same range as ordinarily produced and are still freely flowing beads or globules.

The spray dried base particles are charged to the tumbing machine, preferably a continuous tumbling drum, at one end thereof and, due to the inclination of the drum, usually from 2 to 15, often 5 to 10, they pass through it while continually tumbling so as to bring them in contact with beads and overspray material. Because the beads are substantially spherical and of rather large particle sizes, areas of contact between the particles are not great and strong aggregates are not formed. Yet, the liquid in the tumbler can be sorbed into the interiors of the particles. Preferably, the spherules will be in the 6 to or 20 to 100 mesh range for best overspray results. Throughput times in the continuous tumbler or a batch tumbler, if that is employed, will usually be from 1 to 20 minutes, preferably from 2 to 15 minutes and most often around 4 to 6 minutes. The tumbling drum will'rotate at about 2 to 30 revolutions per minute, usually 4 to 20 r.p.m. for best treatments.

Along with the base beads may be added finely divided sodium carboxymethyl cellulose or other anti-redeposition agents of particle sizes that pass through a 200 mesh sieve, so that it is dry mixed with the detergent base beads, usually before application thereto of perfume or overspray nonionics. Other particulate solids, such as builders and fillers, may be added together with or at about the same locations in the drum as that at which the beads are added. Usually, the different particulate solid materials added are sufiiciently mixed in the first 5 to 15% of the length of the tumbling drum and after such point liquids may be added.

Due to the rotation of the drum the particulate materials are lifted upwardly along the upwardly rising drum Wall and fall downwardly before reaching the drum top, forming a continually surface-changing section or particle screen against which the liquid overspray may be directed. Thus, the overspray will normally be aimed at such surface at an angle inclined from the vertical toward the surface. It will be apparent to one skilled in the art how this angle should be adjusted to obtain most effective covering of the particles with the liquid sprays. The most preferred direction will be that in which the sprayed droplets, whether of overspray material, perfume or other liquid, are directed onto the most rapidly moving portion of the base particles in the tumbler without contacting any quiescent sections of such particles and Without touching tumbler walls or parts. Of course, the sprays should also avoid being directed at the inlets for the base beads, CMC or other powdered materials and should not be aimed at such incoming constituent streams.

The liquid droplets of sprays will usually be in the 50 to 500 micron diameter range, preferably 50 to 250 microns. Such very fine particles tend to coalesce less and often a portion thereof will be carried as a fog through at least the early part of the tumbling apparatus, facilitating gradual contact with the base particles and allowing penetration of the liquid overspray without causing lumping or tackiness. The mass transfer of liquid overspray surface active agent and any accompanying nonionic detergent through the detergent base bead is important for obtaining free flowing and non-tacky particles and gradual contact of finely divided liquid with quickly moving or tumbling base particles allows the proper penetration of the liquid and contributes to satisfactory production of a free flowing product.

After tumbling for the desired time, the finished product is removed and without any special cooling being required, is packaged, following the procedure previously described, illustrated in the drawing. Such packing takes place within minutes or less after removal of the product from the tumbling drum and when packed, the beads, which may still be warm, are so retentive of the overspray liquid (which will often still be in the liquid state, inside the base particles) that the particles will not stain any untreated cardboard carton. With waxed, resin-coated or otherwise treated cartons, results will be even better and the products will not cake, lump or become tacky on prolonged storage. Thus, the nonionics are sorbed by the beads sufficiently within the tumbling period to make the particles free flowing and not badly sticky. Their sorption coefficients are high with from 2 to 20% of nonionic overspray being sorbed by a 6 to 200 mesh bead within 1 to 15 minutes. Flowability of the particles will be further improved if they have dusted onto the surfaces thereof a flow-inducing agent, such as Satintone or other suitable powdered constituent, toward the downstream end of the tumbler.

Within the proportions and conditions mentioned in this specification useful oversprayed detergent products are manufactured. A principal advantage of these products is in their desired content of nonionic surface active compound which may have a nonionic detergent present with it. Yet, although it is diflicult to spray dry any appreciable quantities of such compounds with other components of a detergent composition, by folowing the present methods a product is obtainable which is like a spray dried bead and yet contains the desired amount of nonionic. Pluming, the production of bluish hazes over spray towers and the accompanying smoke and air pollution are obviated. Of course, for vest processing and product results, the components, amounts thereof and conditions of treatment will be modified within the ranges given. For example, in compositions in which it is desired to include comparatively large quantities of silicate, which, although is a usual upper limit, it might be wanted to extend to as much as of the product, the very fact that silicate inhibits penetration by the nonionic compounds militates against more than 15% of it being included in the crutcher mix. Thus, the remainder will normally be separately produced in granular form and will be blended in with the detergent base or oversprayed particles in the early or late portions of the tumbling apparatus. Then too, if any CMC, NTA, sodium sulfate or anionic detergent, such as linear alkyl benzene sulfonate is present in the base detergent in large quantities, or a combination thereof is present in such quantity, so that sorption of the nonionic would be inhibited, portions of these materials might well be post-added. This is especially true of the CMC since only a small quantity of that material is tolerable in the crutcher mixer without causing tackiness in the product after post spraying. Additionally, materials which aid penetration of the nonionic, such as sodium carbonate, might well be increased in crutcher mixes which contain inhibiting compounds, too. The amounts of lubricants or flow-inducing powder such as Satintone should be increased if there is a danger that the product will not flow well, due to content of too much of materials which inhibit sorption of the nonionics. In a similar manner, the rule of reason with respect to formulation is applicable to the types of nonionics that are employed. For example, where there are present some penetration-inhibiting matetials, it may well be preferable to utilize smaller quantities of the nonionics and the nonionics should preferably be of more fluid type, such as those of lower degrees of lower-alkoxylation. These penetrate the detergent base beads better and do not leave appreciable sticky residue on the surfaces of the beads.

In the specification the terms minor, major, substantial, substantially entirely and substantially all have been employed to describe various concentrations or proportions of materials. As so employed, minor means under 50%, major stands for more than 50%, substantial and substantially mean over and substantially entirely and substantially all indicates over 98%.

Various advantages attending the practice of this invention are unexpected and are significant. Thus, the fact that the liquid nonionic surface active agent does not bleed from the detergent beads and make them tacky is surprising. Similarly, the use of such surface active agent in conjunction with nonionic detergent to overspray detergent beads and not obtain a sticky product is unexpected. That detergent particles which resemble spray dried detergents in their flowability are producible by this method would not have been predicted. Rather, it would have been expected that the beads would agglomerate, lose their spherical outlines, increase in particle size and be of diminished flow rates. Strangely enough, in most cases the bulk density of the product does not change during treatment, nor does its particle size distribution vary much from that of the starting material. It might well have been anticipated that the addition of liquid post-spray would cause a significant increase in bulk density of the particles. That the process of overspraying should be so etficient and so quickly effected is surprising, as is a noted lack of criticality with respect to continuing the tumbling for substantial periods of time, up to 30 minutes, after completion of normal sorption of the overspray. It would normally be expected that such additional tumbling would be detri mental to the detergent bead but such is found not to be the case.

An important advantage noted for the products is that the fluorescent dye or optical brightener incorporated in the crutcher mix, when the detergent particles containing it are oversprayed, whitens the product much more than the same amount of dye in a product which has not been oversprayed. It appears that the nonionic overspray material encourages migration of the fluorescent dye to the surfaces of the beads, increasing their concentrations at the bead exteriors. Such a mechanism can also be useful in maintaining concentrations of perfumes and similar adjuvant materials higher at the outside of the detergent particles than in the interior, giving it a greater appeal to the consumer or allowing a saving in the quantity of perfume employed. It has also been theorized that the nonionics may also improve the transparency or transluscency of the surfaces of the particles, thereby better enabling the optical brighteners to whiten the product.

In addition to the mentioned unexpectedly beneficial results, the present processes and formulations allow the making of excellent, free flowing detergent products by eflicient and practicable means, utilizing available equipment and actually improving its capacity.

The following examples illustrate the invention but should not be considered as limiting it. Unless otherwise mentioned, all temperatures are in F. and all parts are by weight.

113. EXAMPLE 1 Weight Water lbs 140 Sodium linear higher alkyl benzene sulfonate detergent base, 56% solids aqueous slurry lbs 100 1 012-15, averaging about Cree.

87.5% active ingredient, the balance being about 10% sodium sulfate and 2.5% unreacted oll (alkyl benzene).

3 9 lbs. 10 oz.

The above components of a detergent base crutcher mix are sequentially added to a crutcher and are mixed therein for 15 minutes to a final temperature of 185 F. The crutcher mix has a specific gravity of 1.27 when it is ready for pumping to a spray drying tower. The method followed is in accordance with the drawing except for the fact that non-vital pieces of equipment and operations have been omitted from the drawing for the purpose of simplicity and similarly, will be omitted from this description.

The crutcher mix is pumped to the spray tower by a positive presure pump producing 800 lbs. gauge pressure at a manifold before the spray nozzle. A single spray nozzle, No. 2-15 Whirljet, is utilized to spray the crutcher mix into the top of the 60 ft. high, 8 ft. diameter countercurrent tower. The inlet air temperature to the tower is 475 F. and the outlet temperature is 400 F. The slurry enters the spray nozzle at 180 F. Residence time in the tower is variable but it is on the order of one to four minutes. Product is withdrawn at the bottom of the tower and is airlifted to a bin from which it is dispensable to a mixing drum or twin shell blender. Experimentation has shown that the actions of the batch and continuous tumbling drums and twin shell blenders are substantially equivalent.

The spray dried detergent base beads, of particle sizes in the 6 to 200 mech range, a substantial proportion of which is in the 8 to 100 mesh range, are found to have a moisture content of 10% upon charging to the tumbling apparatus. They are also of a density of about 30 lbs. per cubic foot and at a temperature of 80 F., when charged. To the continuous tumbling drum are added 96 parts of the base bead (10% moisture), 3 parts of Neodol 25-3, containing moisture, 0.8 part proteolytic enzyme and 0.15 part perfume. The tumbler is operated at 25 r.p.m. and blending takes 2.5 minutes, with the initial 30 seconds being allowed for blending the enzyme prills with the detergent beads in the early part of the blending operation. The prills are of particle sizes approximating those of the detergent base beads. The liquid Neodol 25-3 and perfume are sprayed into the mixer so as to have particle sizes of approximately 50-100 microns as they are directed against a wall of falling detergent beads, utilizing 40 lbs./sq. in. gauge air pressure to the Spray Systems Inc. round spray cone atomization nozzle. After completion of mixing, the beads are Withdrawn and are immediately (within one minute) packaged in cardboard cartons, which are sealed and sent to storage.

Subsequently, the detergent produced is checked for flow properties and tackiness by tests found to be satisfactorily indicative of the mentioned characteristics. The flow rate is found to be 62%, compared to the flow of a standard sand through a particular orifice. This is a gOod' flow rate for synthetic detergents, since 55% to 74% is considered to be an acceptable range for detergent flows, and because the flow rate compares favorably with the untreated detergent beads containing no sprayed on nonionic surface active agent. When tested for tackiness, the product is found to be non-tacky, having a tackiness number of 0. This test is one in which detergent particles are placed in a cylindrical form approximately five inches high and having a cross-sectional area of about ten square inches. A ten pound weight is placed on the detergent, the form and Weight are removed, and weights are placed on the top of the detergent cylinder resulting until it collapses. A rating of 0 indicates that the detergent beads did not adhere to each other at all despite the molding pressures applied; thus, they were not tacky. The detergent particles are of a specific gravity or bulk density about the same as that of the beads before overspraying thereon of the nonionic surface active agent.

The above-described overspraying procedure is one in which a tumbling drum like that of the drawing is used and in which the overspraying operation is continuous. However, when a batch operation is effected with the same equipment, except for the installation of bafiles to maintain good mixing throughout the drum, the changing of the angle of the drum from about 3 to 0 and the more central addition of materials and the direction of overspray thereon, equally good results are obtained. Similarly, when a suitable continuous or batch twinshell blender is employed, such results are also obtained. However, for ease of manufacture and control of product quality, the continuous drum blender is preferred.

Various other changes are made in the product formula and processing techniques and good non-tacky, free flowing products are made, in accord with the invention. Thus, when the enzyme is omitted, 3% sodium carboxymethyl cellulose is present instead, also replacing some of the pentasodium tripolyphosphate, a non-tacky and free flowing detergent is made, if the CMC is tumbled in with the other ingredients in the drum, rather than being incorporated in the crutcher mix. Yet, if in the crutcher, the CMC impedes penetration of the detergent beads by the nonionic and sticky product results.

When, in addition to the Neodol 25-3 in the overspray, 3 parts of Neodol 45-11 are also present, the combined nonionic surface active agent and detergent, in solution in each other, are readily absorbed by the detergent beads and result in a free flowing oversprayed product of improved detergency, due to its content of additional nonionic detergent. The additional detergent improves washing and whitening effects on laundry whereas the surface active nonionic is most useful in helping to solubilize oily stains on clothing washed.

Instead of Neodol 25-3 in the overspray Neodol 25-7 is used, with good results, too. To improve penetration of this thicker nonionic some of the tripolyphosphate (10 to 50% thereof) is replaced by sodium carbonate, the larger proportions being used when from 3 to 5% Neodol 45-11 is also present, with either the Neodol 25-3 or 25-7 as the nonionic surfactant. Such products are also free flowing. Further changes in formulations include variations in the proportions of base detergent ingredients listed, within the ranges recited in the specification. Thus, 10 or 20% increases or decreases in the amounts of the mentioned constituents may be made without appreciable effects on the desirable properties of the products. Also, when some of the anionic detergent is replaced by other anionics, e.g., sodium lauryl sulfate, :20 tallow:coco soap or sodium alkyl sulfonate, to the extent of 2 to 3 percent replacement, the product made is free flowing and of good detergency. The same applies when Neodol 25-7 or mixtures of the surface active Neodols with Neodol 45-11 or other detergent nonionics of this type are in the overspray. Also, when 2% of the sodium tallowzcoco soap is added to the rest of the formula in the crutcher mix the product is a good detergent of nontacky characteristics. It flows slower than the reported product but is still within the allowable free flowing range, according to the flow test results and visual observation.

A surprising observation made during the running of these experiments is that the fluorescent brightener is of appreciably more effect in the post-sprayed detergents than in controls, apparently due to being drawn nearer to the bead surface by the presence of the nonionic surfactant(s). This phenomenon is observed whether the nonionic is applied as a spray at about 80 F., as in the present case, or at higher or lower temperatures within the range specified. However, usually the temperatures of the nonionics sprayed are at least ten degrees Fahrenheit over their solidification points.

An additional modification of the working example is made when dibutyl phthalate is substituted for a significant proportion of the Neodol 25-3. Thus, with 30% replacement of the nonionic surface active Neodol a thinning effect is noted in the spraying liquid and the overspray readily penetrates the base beads. The product has oily stain removing properties contributed by both the Neodol and the phthalate, is free flowing and does not stick together on storage.

EXAMPLE 2 A detergent base bead is made according to the method described in Example 1 but with the crutcher constituents so chosen as to result in a product containing 6% linear tridecyl benzene sulfonate, sodium salt; 34% sodium tripolyphosphate; 6% of the described silicate and 37.85% sodium sulfate, all on a finished product basis. Onto such beads, containing 10% H O, is oversprayed a solution of Neodol 25-3, Neodol 45-11 and perfume, to result in a final product of the type within this invention, containing 3% Neodol 25-3, 3% Neodol 45-11 and 0.15% perfume. The sprayed liquid is of particle size within the 50 to 500 micron range, on the low side thereof, and the beads are of 8 to 100 mesh. Tumbling is in a twin shell blender (batch) and lasts for about four minutes. The nonionic overspray liquid is initially at about room temperature, 75 F., and the beads treated are at 104 F., having been recovered from the tower airlift only a couple of minutes before being oversprayed.

The product drawn off is free flowing (rating of 67%) and non-tacky (rating of These figures are exactly the same as those for the untreated beads. The product may be packed immediately after manufacture and the packaged material is free flowing after months of storage. =Bulk density of the product is 35.5 lbs./ft. compared to 36.6 lbs/ft. for the starting beads. It will also be noted that the particle sizes are in the 8 to 80 mesh range, compared to the original 8 to 100 mesh.

The detergency of the product is good although the content of anionic detergent is fairly low and that of supplementing nonionic detergent raises detergent content to less than 10%.

As in the preceding example, when changes are made in the formulation, such as the addition of borax, phosphate, CMC enzymes and Satintone to the tumbling drum, in the amounts mentioned in the preceding specification, good free flowing final detergent particles are the result. Similarly, when processing conditions are altered but kept within the ranges described, results are good and acceptable product is made.

EXAMPLE 3 A spray dried base bead made according to the method of Example 1, is oversprayed promptly after manufacture with mixed materials to give 6% Neodol 25-3, an additional 4% Neodol 45-11 and 0.15% perfume. The tumbling is effected in a drum of 1:2 diameter to length ratio, inclined at an angle of about 5 and rotating at 34 r.p.m. The liquid spray is at room temperature and the particle size is 50 to 100 microns. The detergent bead temperature is about 90 F. Product is of a bulk density of about 0.5 g./cc., 9.7% moisture content, rates 59% in flowability and is non-tacky.

EXAMPLE 4 The experiment of Example 1 is repeated but with 16 Neodol 25-7 used instead of Neodol 25-3. Product density is .5 g./cc., moisture content is 9.5%, flow is 64% and operations in the 18 ft. x 6 ft. dia. drum, rotating at 4.5 r.p.m. proceed smoothly. The product resulting is an acceptable free flowing detergent.

The invention has been described with respect to examples and illustrations of embodiments thereof but is not to be considered as limited to them, since it will be clear to one of skill in the art how to substitute equivalents and modify the operations without departing from the spirit of the invention.

What is claimed is:

1. A method of preparing a particulate detergent composition which comprises spraying onto a particulate base detergent composition consisting essentially of synthetic anionic organic detergent, inorganic builder salt for the anionic detergent, said salt containing alkali metal silicate having an MeOzSiO ratio of from 1:16 to 1:3.4, wherein Me represents alkali metal, a composition consisting essentially of linear C -C alkoxy poly-C C alkoxy- C -C alkanol nonionic compound wherein the poly C -C alkoxy-C -C alkanol content of the nonionic compound is from 39-60% by weight, to produce a final product containing from 5 to 15% by weight of said anionic detergent, from 5 to 35% by weight of alkali metal silicate and from 2 to 20% by weight of said nonionic compound.

2. A method according to claim 1, wherein said base detergent composition is of a moisture content less than 15% said anionic detergent is linear higher alkyl benzene sulfonate, the poly-lower alkoxy lower alkanol portion of said nonionic compound is of 6 to 14 carbon atoms, the moisture content of which, as applied, is less than 5%, the temperature of which, as applied, is from 10 to 65 C. and the temperature of the base particles to which the nonionic compound is applied is from 10 to 65 C.

3. A method according to claim 2 wherein the alkyl portion of said alkyl benzene sulfonate contains from 12 to 15 carbon atoms.

4. A method according to claim 1, wherein from about 5 to 15% by weight of the sodium silicate present in the final product is present in the particulate base detergent composition, the remainder being added subsequent to contacting said base detergent composition with said nonionic compound.

5. A method according to claim 1, wherein said particulate base detergent composition contains from 10 to 40% by weight of the final product of sodium tripolyphosphate.

6. A method according to claim 1, wherein the overspray composition is in the form of finely divided liquid droplets and is sprayed onto the surfaces of said particulate base detergent composition.

7. A method according to claim 1, wherein said particulate base detergent composition contains from 5 to 35 by weight of the final product of sodium carbonate.

8. A method according to claim 1, wherein said particulate base detergent composition contains from 5 to 25% by weight of the final product of borax.

9. A method according to claim 1, wherein said particulate base detergent composition contains up to 40% by Weight of the final product of sodium sulfate.

10. A method according to claim 1, wherein from 10 to 40% of the nonionic compound is replaced by di-lower alkyl phthalate.

11. A method according to claim 1, wherein the temerature of said particulate base detergent is from 27 to 43 C.

12. A method according to claim 6, wherein the diameter of said overspray detergent composition is from 50 to 500 microns.

13. A method according to claim 1, wherein said particulate base detergent composition is in the form of spherules having a particle size such that they substan- 1 7 tially pass through a No. 6 U.S. Sieve and remain on a No. 100 U.S. Sieve.

14. A method according to claim 1, wherein said spraying is effected in a tumbler drum from Which treated product is continuously removed, the tumbler turns at a speed of 4 to 20 revolutions per minute and the treated product is removed within 2 to 15 minutes after charging.

15. The product prepared in accordance with claim 1.

16. The product prepared in accordance with claim 2.

References Cited UNITED STATES PATENTS 3,519,570 7/1970 McCarty 252135 3,501,408 3/1970 Gabler et al. 252-135 3,598,743 8/1971 Coates 252-99 3,630,920 12/1971 Freifeld et al. 252-90 3,144,412 8/1964 Inamarato 252539 FOREIGN PATENTS 206,916 12/ 1955 Australia. 1,191,356 5/1970 Great Britain.

491,125 3/1953 Canada.

1 8 528,287 7/1956 Canada. 511,415 3/1955 Canada. 510,555 3/1955 Canada. 586,622 11/1959 Canada. 586,740 11/1959 Canada.

OTHER REFERENCES Neodol Surfactants, Shell Chem. Co. Bulletin, 1967,

pp. 5, 6, 9 and 13.

The Condensed Chem. Dict., 7th Ed., Reinhold Pub- P. E. WILLIS, Assistant Examiner U.S. Cl. X.R.

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