IE48186B1 - Detergent compositions - Google Patents

Abstract

A free-flowing particulate detergent composition suitable for heavy duty laundering in hard water, comprising particles of ion exchanging zeolite and nonionic detergent, with a water-soluble inorganic builder salt which consists of or includes alkali metal pyrophosphate or a mixture of alkali metal carbonate with alkali metal bicarbonate or with alkali metal silicate. Methods for the manufacture of such compositions involve combinations of spray drying and post-addition techniques.

Description

PETSRGENT COMPOSITIONS This invention relates to laundry detergent compositions and to methods for the manufacture thereof. More particularly, it relates to free flowing, particulate, heavy duty detergent composi5. tions based on nonionic detergent, ion exchanging zeolite builder and water soluble builder salt or salt mixture.

Heavy duty synthetic organic detergent compositions based on anionic synthetic organic detergents . and pentasodium tripolyphosphate builder salt are well known and have been commercially accepted as superior products which are especially useful in hard water. Nonionic organic detergents have been included in such compositions. It has often been . observed that in such compositions pentasodium tripolyphosphate has been superior to tetrasodium tripolyphosphate. In recent years various other builders have been utilized in place of phosphates so as to diminish the danger of eutrophication of . inland waters into which wash waters containing such phosphates might be discharged. Although various water-soluble builders have been successfully employed for improving detergency of synthetic organic detergents in such compositions, often these . had negative attributes which limited or prevented their acceptance. For example, trisodium nitrilotriacetate (NTA) has been rejected in some areas because of an allegedly carcinogenic effect in . combination with other materials which might be found In inland waters. Other non-phosphate builder salts have been objectionably expensive or less effective. Insoluble ion exchanging materials such as zeolites . have recently been suggested as comparatively innocuous builders for detergent compositions. In some situations they may partially replace phosphate builders and in other cases they allow the total replacement of such builders, sometimes in conjunc10. tion with other non-eutrophying water soluble buiIders.

In the present invention a nonionic detergent is the primary surface active and detersive material employed and an ion exchanging zeolite is utilized . as a builder for such detergent. Additionally, suitable water-soluble builder salts are also present to improve further the properties of the detergent compositions made.

In various preferred aspects of the invention . such builder is a mixture of alkali metal carbonate with alkali metal bicarbonate or a mixture of alkali metal carbonate with alkali metal silicate, in certain proportions. In such cases an excellent product can be made without any need for the . presence of phosphorus in the composition.

According to the present invention a freeflowing, particulate, heavy duty, laundry detergent composition of a bulk density greater than 0.6 gm/ml comprises a water-soluble nonionic detergent absorbed . into spray-dried beads having a moisture content of 27o to 157ο by weight and comprising a mixture of calcium ion exchanging zeolite of the empirical oxide formula (Na20)x.(Al203)7.(SiO2)z.wH2O . wherein x is 1, y is from 0.8 to 1.2, z is from 1.5 to 5.0 and w is from 0 to 9 and either sodium carbonate or a mixture of sodium carbonate and sodium bicarbonate in a weight ratio in the range of 3:8 to 5:1, with the proviso that the weight ratio on an an10. hydrous basis of zeolite to sodium carbonate is in the range of 1:0.1 - 1.5 in the absence of sodium bicarbonate and the weight ratio of zeolite to sodium carbonate and sodium bicarbonate is in the range of 1:0.3 - 1.6:0.2 - 2.0, with the further proviso that . spray-dried beads containing no sodium bicarbonate ace admixed with from 0.1 to 0.3 parts by weight on an anhydrous basis of particulate hydrous sodium silicate having an Na2O:SiO2 mole ratio in the range of 1:1.5 to 1:2.5 prior to absorption of 0.2 to 1.6 . parts by weight of said nonionic detergent on the zeolite carbonate-bicarbonate beads or 0.2 to 1.5 parts by weight of said nonionic detergent on the mixture of zeolite-carbonate beads and particulate silicate to yield a composition containing 157, to . 25% by weight of said nonionic detergent.

Nonionic detergents are listed at length in McCutcheon's Detergents and Emulsifiers, 1973 Annual and in the textbook Surface Active Agents, Vol. II, by Schwartz, Perry and Berch (Interscience Publishers, 1958). Such detergents are usually pasty or waxy solids at room temperature (20°C) which are either sufficiently water-soluble to dissolve promptly in water or will quickly melt at the temperature of the wash water, as when that temperature is above 40°C.

The nonionic detergents employed will not usually be those which are normally liquid at room temperature because those might tend to make a tacky product which would not flow easily and might lump or set on storage, but nevertheless, small quantities of liquid detergents are sometimes desirably used. Typical useful nonionic detergents are poly - (lower alkenoxy) derivatives that are usually prepared by the condensation of lower (2to4 carbon atoms) alkylene oxide, e.g. ethylene oxide or propylene oxide (with enough ethylene oxide to make a water-soluble product), with a compound having a hydrophobic hydrocarbon chain and containing one or more active hydrogen atoms, such as higher alkyl phenols, higher fatty acids, higher fatty mercaptans, higher fatty amines and higher fatty polyols and alcohols, e.g. fatty alcohols having 8 to 20 or 10 to 18 or 12 to 18 carbon atoms in an alkyl chain and where alkoxylation is by an average of about 3 to about 30, preferably 6 to 20 and more preferably 5 to 15 lower alkylene oxide, e.g. ethylene oxide, units. Preferred nonionic detergents are those represented by the formula R0(C2H40)nH wherein R is the residue of a linear saturated primary alcohol (an alkyl) of 12 to 18 carbon atoms and n is an integer from 6 to 20 or 5 to 15. The preferred nonionic detergents may be referred to as higher fatty alcohol polyoxyethylene ethanols (the terminal ethanol of these ethers is included in the number of oxyethylene groups counted in the mol of the nonionic). Typical commercial nonionic surface active agents suitable for use in the invention include Neodol 45-11, which is an ethoxylation product (having an average of about 11 ethylene oxide units) of a 14 to 15 carbon atom (average) chain fatty alcohol (made by Shell Chemical Company, U.S.A); Neodol 25-7, a 12 to 15 carbon atom chain fatty alcohol ethoxylated with an average of 7 to the ethylene oxide units; and Alfonic 1618-65, which is a 16 to 18 carbon alkanol ethoxylated with an average of 10 to 11 ethylene oxide units (Continental Oil Company, U.S.A). Also useful are the igepals of GAF Co., Inc., U.S.A. NEODOL, ALFONIC and IGEPAL are trade marks. In the above description higher, as applied to higher alkyl, higher fatty, etc., means that fror 8 to 20, preferably from 12 to 18, carbon atoms are present.

The zeolites utilized in the compositions of the present invention include the crystalline, amorphous and mixed crystallineamorphous zeolites of natural or synthetic origin or mixtures thereof that can be of satisfactorily quick and sufficiently effective hardness ion counteracting activity. Preferably, suer. materials are able to react sufficiently rapidly with a hardness cation such as calcium, magnesium or iron, to soften wash water before adverse reactions of such hardness ions with any constituents of the detergent compositions. A useful range of calcium ion exchange capacities is from about 200 milligram equivalents of calcium carbonate hardness per gram of aluminosilicate to 400 or more of such milligram equivalents (on an anhydrous basis). Preferably such range is from 250 to 350 milligram equivalents per gram.

The water-insoluble crystalline aluminosilicates used are often characterized by having a network of substantially uniformly sized pores in the range from about 3 to about 10 Angstroms, often being about o 4 A (nominal), such size being uniquely determined by the unit structure of the particular type of zeolite crystal. Of course, zeolites containing two or more such networks of different pore sizes can also be satisfactorily employed, as can be mixtures of such crystalline materials with each other, and with amorphous materials.

The zeolite should be anunivalent cation-exchanging zeolite, i.e. it should be an aluminosilicate of an univalent cation, such as sodium, potassium, lithium (when practicable) or other alkali metal, ammonium or hydrogen. Preferably the univalent cation of the zeolite molecular sieve is an alkali metal cation, especially sodium or potassium, and most preferably is sodium, but various other types are also useful.

Crystalline types of zeolites known as molecular sieves which are useful in the compositions of the invention include zeolites of the following crystal structure groups: A, X, Y, L, mordenite, and erionite, of which types A and X are preferred. Mixtures of such molecular sieve zeolites can also be useful, especially when type A zeolite is present. These crystalline types of zeolites are well known in the art and are more particularly described in the textbook Zeolite Molecular Sieves, by Donald U. Breck, published in 1974 by John Wiley & Sons, U.S.A. Typical commercially available zeolites of the aforementioned structural types are listed in Table 9. 6 at pages 747-749 of the Breck book.

Preferably the zeolite used in the compositions of the invention is synthetic and it is also preferable that it be of type A or similar structure, particularly described at page 133 of the aforementioned Breck book. Good results have been obtained when a Type 4A molecular sieve zeolite is employed, wherein the univalent cation of the zeolite is sodium and the pore size of the zeolite is about 4 Angstroms.

Molecular sieve zeolites can be prepared in either a dehydrated or calcined form which contains from about 0 or about 1.5% to about 3% of moisture, or in a hydrated or water loaded form which contains additional bound water in an amount from about 4% up to about 36% of the zeolite total weight, depending on the type of zeolite used.

The water-containing hydrated form of the molecular sieve zeolite is preferred in the practice of this invention. The manufacture of such hydrated crystals is well known in the art. For example, in the preparation of Zeolite A, referred to above, the hydrated zeolite crystals that are formed in the crystallization medium (such as a hydrous amorphous sodium aluminosilicate gel) are used without the high temperature dehydration (calcining to 3% or less water content) that is normal practice in preparing such crystals for use as catalysts, e.g. cracking catalysts. The crystalline zeolite, in either completely hydrated or partially hydrated form, can be recovered by filtering off the crystals from the crystallization medium and drying them in air at ambient or other suitable temperature so that their water contents are as desired, usually being in the range from 5% to 30% moisture, preferably from 15 to 22%. However, because at least partial hydration of the zeolite may sometimes occur during manufacture of the compositions of the present invention, the moisture content of the molecular sieve zeolite being employed may sometimes be as low as zero at the start of the process of manufacturing the detergent compositions, and sometimes anhydrous zeolite can be present in the final product.

Preferably the zeolite to be used will be initially in a finely divided state, the ultimate particle diameters being below 15 microns, e.g. in the range from 0.001 to 15 microns, preferably in the range from 0.01 to 10 microns and especially preferably in the range from 0.01 to 8 microns in mean particle size, e.g. 4 to 8 microns if crystalline, and from 0.01 to 0.1 micron, e.g. 0.01 to 0.05 micron if amorphous.

Although the crystalline synthetic zeolites are more common and better known, amorphous zeolites may be employed instead and are often superior to the crystalline material in various important properites, as will be described, as may be mixed crystalline-amorphous materials and mixturesof the various types of zeolites described. The particle sizes and pore sizes of such materials will usually be like those previously described, but variations from the described ranges may be made, provided that the materials function satisfactorily as builders in the detergent compositions and do not objectionably overwhiten dyed materials treated with the detergent compositions in aqueous media.

While the formula of some amorphous zeolites may be represented by M20.Al203. (SiO2)z.w H20 wherein M is a monovalent cation, preferably an alkali metal, z is from 1.5 or 2.0 to 3.8 or 4 (2 is sometimes preferable) and w is from 2.5 to 5, especially when M is sodium, the formula may be varied to (Na2O)x.(Al2O3)y. (Si02)z.wH20 and usually, when x is 1, y will be from 0.8 to 1.2, z will be from 1.5 to 5 and w will be 0 to 9, such limits preferably being 0.9 to 1.1, 2.0 to 3.8 and 2.5 to 6 or 3.0 to 4.5 when x is 1. The chemical or structural formula will preferably be the following, or approximately so: (Na2O)6(Al2O3)6(SiO2)12.27 Hz0 but the mols of water present may be 20 to 27·, e.g. 24 to 27. In such chemical formula the x : y : z : w ratio is 1:1 : 2 : 4.5.

The silicate may be any suitable water-soluble silicate and is preferably an alkali metal silicate, more preferably a sodium silicate, the alkali metal oxide : silica ratio thereof being in the range from 1:1.6 to 1:3.8 or 1:4, preferably from 1:2 to 1:3 and more preferably about 1:2.4 e.g. 1:2.35. Thus, a most preferred silicate is that of Na20:Si02 ratio of about 1:2.4.

Although the essential components of the heavy duty built detergent compositions are the nonionic detergent, zeolite and specified builder salts, there will almost always be present some free moisture which may or may not include waters of hydration of the various components of the composition. Such moisture is removable by heating to a temperature of 105°C for five minutes.

Together with moisture, other preferred addi5. tional components of the compositions include alkali metal sulphate and other adjuvants generally utilized in the preparation of synthetic detergent compositions, With respect to alkali metal sulphates, the sodium and potassium salts and . mixtures thereof may be utilized but the sodium salts are highly preferred. Such may be employed as salt cake, in the anhydrous form, or as the sodium sulphate decahydrate, or in some cases, as the bisulphate in anhydrous form or as the monohydate.

. When the bisulphate is utilized the amount thereof will normally be about the same as that of the sulphate it would be replacing.

Various adjuvant materials that may be present include the conventional functional and aesthetic . adjuvants, such as bleaches, e.g. sodium perborate; colourants, e.g. pigments, dyes and optical brighteners; foam stabilizers, e.g. alkanolamides, such as lauric myristic diethanolamide; enzymes e.g. proteases; skin protecting and conditioning agents, . such as water-soluble proteins of low molecular weights, obtained by hydrolysis of proteinaceous materials, such as animal hair, hides, gelatin and collagen; foam destroyers, e.g. silicones; fabric softeners, e.g. ethoxylated lanolin; bactericides, . e.g. tetrabromosalicylanilide; opacifying agents, e.g. polystyrene suspensions and behenic acid; buffering agents, ___ e.g. alkali inetal bocates; perfumes; and flow improving agents, e.g. ground clays.

In one preferred aspect of the present invention a free-flowing phosphate-free particulate heavy duty . detergent composition is made which is of a bulk density greater than 0.6 g/ml and which comprises beads of ion exchanging zeolite, sodium carbonate and sodium bicarbonate in which the proportions of these components are in the range of 1:0.3-1.6:0.210. 2.0, on an anhydrous basis, having absorbed into them from about 0.2 to about 1.6 parts of nonionic detergent. Such a composition has been found to deposit less residue on washed materials than do various other heavy duty laundry detergent composi15. tions in which comparable quantities of zeolite builder are present. Additionally, the present compositions can be made in characteristic spray dried particulate form, which may contribute to their effectiveness as detergents, and also to . marketability. It is known that a useful detergent composition can be made by tumbling a mixed carbonate-bicarbonate salt, such as Wegscheider' s salt, with nonionic detergent and coating the product with zeolite in powder form. However, such . products may be of somewhat different appearance from that of conventional detergents and therefore might not be as readily acceptable in the marketplace. Furthermore, spray dried products tend to be more uniform in composition and are manufactured . with equipment which is generally available in plants for the manufacture of detergents and which is familiar to operators therein.

A method for the manufacture of such preferred compositions comprises spray drying a mixture of ion exchanging zeolite, sodium carbonate, sodium bicarbonate and water to a moisture content in the range from about 2% to about 15%, so that the proportions of zeolite, sodium carbonate and sodium bicarbonate in the spray dried beads produced are in the range of 1:0.3 - 1.6 : 0.2 - 2.0, and mixing with the beads from 0.2 to 1.6 parts of nonionic detergent, in liquid form, per part of zeolite, so that the nonionic detergent is absorbed into the beads.

The nonionic detergents that are utilized to make the zeolitecarbonate-bicarbonate-nonionic compositions of the invention are essentially the same as those described heretofore. However, a normally liquid nonionic detergent may also be utilized and a preferred nonionic is Neodol 25-6.5, which includes 6.5 moles of ethylene oxide per mol of detergent. The liquid nonionics, when applied to the base beads, will preferably be applied to beads which are warm enough for the liquid to penetrate into the bead interiors, which results in a product which has good flow properties. Preferred nonionic detergents of this aspect of the invention are those having 5 to 20, more preferably 5 to 12, lower alkylene oxide units per mol. The zeolites employed are those previously described with respect to the first aspect of this invention.

The alkali metal carbonate and alkali meta bicarbonate may be in the form of a mixture thereof wherein both types of compounds are present in the same individual beads or particles, or may be separate. Such materials will desirably be of particle sizes in the 20 to 100 mesh range, but various other sizes of particles, up to about 8 mesh and as fine as 200 mesh, may . 48186 be used providing that they dissolve and/or disperse readily in the aqueous crutcher mix. Solutions may also be employed, provided that moisture contents of the crutcher mix are not thereby made too high. Normally the alkali metal (sodium or potassium being preferred) carbonates and bi carbonates, most preferably as the sodium salts, will be essentially anhydrous in preferred embodiments of the invention but partially hydrated builder salts of this type may also be used. The proportion of alkali metal carbonate to alkali metal bicarbonate, by weight, will generally be in the range from 3:8 to :1, preferably in the range from 1:2 to 2:1, more preferably about 4:3 in the final product, and of such proportions, plus about 40% to 60%, e.g. about 50%, to 6 for the bicarbonate and minus 25 to 45%, e.g. about 35%, to 2 for the carbonate amounts in the crutcher mix so that the ratio therein would be 3:1 for bicarbonate:carbonate. The mixed salt, if employed, may be made by a method which results in a substantial content, e.g. from 10% to 100%, of Wegscheider's salt, with any balance being sodium bicarbonate. Such a product and the carbonate and bicarbonate components are readily made into a suitable aqueous slurry with the zeolite and water, which slurry is easily spray dried to particles which readily sorb nonionic detergent. Methods for the manufacture of mixed carbonatebicarbonate products, such as those available from Allied Chemical Corporation, U.S.A., under the name Snowlite, e.g. Snowlite I and Snowlite II, have been described in the patent literature.

The water of the crutcher mix and of the final product is preferably deionized water or water which may be present as the solvent in aqueous solution or dispersion of one or more of the components of the crutcher mix. The water employed, if added, will usually have a hardness content of less than 150 ppm, preferably less than 50 ppm and more preferably less than 10 ppm, calculated as calcium carbonate. Although deionized water is preferable, tap waters low in hardness contents may also be employed. The moisture contents of the products are those which are removable by heating to a temperature of 105°C for five minutes.

The alkali metal silicate which may be present in the compositions of this invention is preferably . sodium silicate of Na2O:3iO2 ratio in the range of 1:1.6 to 3.2, preferably 1:2 to 1:3 and most preferably about 1:2.4, e.g. 1:2.35. Such silicate may be added to the aqueous crutcher mix as an aqueous solution, usually containing about 40% of . sodium silicate solids. Alternatively, an equivalent silicate may be post-added to the product, but tnis can result in somewhat less desirable final product properties, such as increased residue on washed materials in some cases, although that can . also result if the spray dried product is overdried and the silicate is dehydrated excessively.

In addition to the main constituents of compositions of this aspect of the invention, already described herein, various supplemental builder . salts, fillers and adjuvants, such as those previously described, may be employed. Among the preferred adjuvants are enzymes, such as proteolytic and amylotic enzymes, fluorescent brighteners and anti-redeposition agents. Exemplary of such . materials are protease and amylase; sodium salts of diaminostilbene disulphonic acid and naphthotriazolyl stilbenes; and sodium carboxymethylcellulose (CMC).

The proportions of active materials in the final product should be in the range 1:0.3-1.6:0.2-2.0: . 0.2-1.6 for zeolite:carbonate:bicarbonate:nonionic detergent. Normally the proportion of bicarbonate to carbonate will be in the range from 1:2 to 2:1. Suitable percentages of various constituents, including water, are from 15% to 40% of zeolite, . from 10% to 25% of carbonate, from 8% to 22% of bicarbonate, from 15% to 25% of nonionic detergent and from 2% to 10% of moisture. Preferably such ranges will be 20% to 30%, 15% to 25%, 10% to 20%, 18% to 22% and 4% to 8%, respectively. Tha silicate . content may be from 3% to 20%, preferably 5% to %. Fluorescent brightener content is normally in the range from 0.05% to 3%, preferably 1% to 2.5%, and proteolytic enzyme content (including the normal carrier for such enzyme) will be from 0.5% to 3%, . preferably 1% to 2%, when present. Various other adjuvants may also he present but the total thereof will not normally exceed 5% and preferably will be less than 3%, percentages of individual components being less than 1% and preferably 0.5% or less.

. Thus, from 0.1% to 0.4% of pigment may be present, as may be 0.1% to 0.4% of perfume. If desired, the percentage of antiredeposition agent may be as high as 3% but normally the percentage thereof, if it is present, will be from 0.5% to 2%.

. The high bulk density particulate heavy duty laundry detergent composition of this .aspect of the invention _ will usually be in free-flowing rounded bead form such as that of other spray dried products, although the bead interior may be virtually honeycombed. The particle sizes of the beads will normally be in the range from 6 to 160 mesh (U.S. Sieve Series), preferably from 8 to 100 mesh, with less than 10%, preferably less than 5% and more preferably less than 1% of the product being outside such ranges. The bulk density of the finished detergent composition will normally be at least 0.6 g/ml, preferably at least 0.65 g/ml and most preferably in the 0.65 to 0.85 g/ml range, e.g. 0.71 to 0.83 g/ml. The flow rates of such products are excellent and usually will be greater than 70% of the rate of free-flowing sand of similar particle size, normally being from 70% to 90% thereof, preferably from 75% to 90% thereof. Although the 0.65 to 0.85 g/ml bulk density range is preferred, by changing formulas and spray drying techniques it can be changed upwardly and downwardly, e.g. to 0.5 to 0.9 g/ml.

In the manufacture of these preferred laundry detergent compositions it is important that a sorptive bead be made for adsorption of nonionic detergent therein. Such sorption should be sufficient for the nonionic detergent to pass into the bead interior and therefore not to tend to cause caking of the beads or poor flow properties. While sodium carbonate of certain types has been found to be an excellent sorbent for nonionic detergents, products made with it alone as the builder, at least in the quantities needed to make compositions of the type which are acceptably detersive, tend to have objectionably high pH's. Also, the presence of bicarbonate with the carbonate appears to be desirable in the making of a free-flowing and absorptive product, as well as for solubilizing the product, and additionally, it exerts its buffering effect. Some of the desirable properties of the product may be enhanced by the decomposition of a portion of the bicarbonate during the manufacture of the zeolite - carbonate - bicarbonate beads, with the resulting escape of carbon dioxide from the product and/or the neutralization of any excess or localized alkalinities by the carbonic acid released.

In the zeolite-sodium carbonate-sodium bicarbonate spray dried beads made in accordance with the invention the proportion of such constituents are in the range of 1:0.3-1.6:0.2-2.0, as previously described for the finished product, with the proportion of bicarbonate to carbonate also being as previously given. The bulk density of the spray dried globules will normally be from 0.5 to 0.7 g/ml (without nonionic having been absorbed). The moisture content of the beads will usually be from 2% to 15%, preferably 5% to 10%. The ranges of contents of other components will similarly have limits higher than those indicated for the finished product, with the increase being a function of the proportion of the final product weight to the spray dried bead. In other words, if for example, the final product is identical in composition with the spray dried product except for the inclusion therein (on a final product basis) of 20% of nonionic detergent post-sprayed onto the spray dried beads and absorbed therein, the percentages of zeolite content in the spray dried beads, would have to be 31.3% to yield a product containing 25% thereof. It should be noted that the spray dried base beads will preferably include no detersive component, such as synthetic organic detergent (including soap), nor will they contain any surface active agents such as wetting agents and emulsifiers, because such components, it has been found, tend to product lower bulk density and less internally absorbent spray dried beads or globules. The particle sizes of the beads made are essentially the same as those of the beads in the finished product and their flow rates will be at least 70% of that of sand of comparable particle size.

In the manufacture of the absorbent yet comparatively high bulk density spray dried detergent beads, the spray drying operation may be conducted in a normal manner, but when silicate is present and is to be spray dried with the other base particle components a particular procedure must be followed so as to allow the incorporation of the desired formula quantity of silicate, especially if such quantity is to be in the range from 8% to 20% and even more especially if it is to be from 10% to 20%. Ordinary mixing or crutching of the base bead components, the zeolite, carbonate and bicarbonate, with or without small quantities of other nonsurface active components, such as stabilizers, brighteners and pigments, may be practiced, followed by conventional spray drying, with powdered silicate, such as hydrous silicates, e.g. hydrous sodium silicate, being post-added, usually with other adjuvants, such as enzyme powders, perfumes and anti-redeposition agents, e.g. sodium carboxymethyl cellulose. In such post-addition processes it is normally desirable for the silicate to be mixed with the base beads prior to the spraying onto the beads of the liquefied nonionic detergent, perfume and other liquid components. However, it is generally better for the enzyme powder, anti-redeposition agent and other such components (which may be of smaller particle sizes than the base particles and also may be less absorbent than the base particles and silicate powder) to be applied after spraying onto the base particles of the nonionic detergent, so that any thin film of nonionic detergent on the surfaces of the base particles or in exposed sub-surface parts thereof, may help to hold the powdered components onto such particles, thereby preventing undesirable sifting and segregation of components in the package.

Although one may add silicate to the base particles, usually in a mixer, such as an inclined cylinder or a Patterson-Keeley or twin shell blender, an improved product of the preferred composition, producing little or no residue on clothing washed with it, even when cold water is employed, may be made by incorporating the silicate in the crutcher and spray drying it from an aqueous crutcher mix with the rest of the base bead components.

By following that procedure it is found that despite the fact that the presence of significant quantities of silicate in the crutcher mix has with other detergent compositions often produced a product of unsatisfactory flow characteristics, which may tend to cake, the present products are free flow ing and absorbent and capable of producing free flowing high bulk density de te rgen t compos i ti ons.

Whether or not the silicate is present in the crutcher mix, such mix will normally include from 40% to 75% of solids and from 25% to 60% of water. Preferably, the water content wi.-Π be from 25% to 40% or 50%, the balance of the mix being non-surface active solids. The crutcher will usually be provided with heat exchange means so that the temperature of the mix may be regulated. Normally it will be in the range from room temperature to 90°C, preferably from 20° to 70°C and most preferably from 45° to 65°C. Crutching times are usually in the range from 5 minutes to one hour, preferably from 10 minutes to 30 minutes. When the silicate is present in the crutcher mix the carbonate, bicarbonate and water, plus any other nonsurface active components to be included in the spray dried base beads, e.g. fluorescent brightener and pigments, are mixed together, usually over a period of from 1 to 10 minutes, preferably from 3 to 7 minutes, and then the silicate is added slowly, preferably as an aqueous solution of from 20% to 45%, more preferably from 35% to 41%, e.g. 40% solids content, with the addition taking from 3 to 7 minutes, until a viscous slurry, usually of a viscosity equivalent to about 100 to 100,000 or more centipoises, is obtained. Such slurry will usually include about J to | of the silicate to be added. During the addition of the silicate, mixing is continued at a comparatively low rate, e.g. with the maximum mixer surface speed being from 2 to 10 metres/second, but after formation of the gelled mix of high viscosity or the viscous slurry high shear is applied to the crutcher mix, wherein the shearing speed is from 20 to 50 or more metres/second, with such shearing continuing for a period normally of from 1 to 20 minutes, preferably from 2 to 10 minutes. After reduction of the viscosity of the mix to a workable range, e.g. to 50 centipoises, low speed mixing is resumed and is continued for another 2 to 20 minutes, preferably 5 to 10 minutes, with the regular and gradual addition of silicate, preferably in solution, over that period of time. Usually, such secondary addition of silicate, especially when it is a very water-soluble sodium silicate of Na20:Si02 ratio of 1:2 to 1:3, e.g. about 1 : 2.4, is unaccompanied by additional gelation to a thick mix, but if it is, the shearing and subsequent addition procedures are repeated until the desired thin crutcher mix of correct composition is obtained. Then the zeolite is admixed with the rest of the crutcher mix, usually over a period of from 1 to 20 minutes, preferably from 2 to 10 minutes.

After completion of crutching the crutcher mix is atomized, preferably by being forced through a circular nozzle of internal diameter in the range from 0.5 to 2 mm, at a pressure of from 10 to 50 kg/cm gauge, into a spray tower, preferably a countercurrent spray tower, in which the drying air is at a temperature of from 150° to 350°C. The tower may be from 8 to 15 metres high and from 2 to 4 metres in diameter, and the product leaving the tower is of particle sizes substantially in the 5 to 160 mesh range and is screened so as to be substantially all within such range or a narrower range, e.g. 8 to 100 mesh. Instead of high pressure atomization of the particles through an orifice, spinning disc atomization or equivalent methods may be employed.

After production of the base particles, when they contain no silicate, a particulate solid silicate, such as hydrous sodium silicate, preferably of the type sold by Philadelphia Quartz Company, U.S.A. as Britesil, of a 1:2 or 1:2.4 Na20 : Si02 ratio, is mixed with the base beads in an inclined drum or other mixing and/or tumbling device, normally over a period of from one to 5 minutes, and nonionic detergent, in liquid state and at a temperature in the range from 20° to 70°C, preferably from 30° to 60°C, is sprayed into the tumbling surfaces of the base beads sometimes mixed with post-added particulate silicate). The atomized globules of nonionic detergent may be of any suitable size but normally are in the 0.5 to 3 mm diameter range, preferably from one to 2 mm diameter. Spray application of the nonionic detergent to the tumbling particles normally takes place over a period of from one to 20 minutes, preferably from 2 to 10 minutes. While the base particles may be heated to temperatures from 30° to 60°C to promote maintenance of normally pasty or solid nonionic detergent in liquid form, this is usually not done because heating of the detergent suffices to accomplish this, and for the normally liquid detergents no heating is needed. After completion of addition of the noniom'c detergent, other materials to be post-added, such as proteolytic enzyme and perfume, may be applied. It is possible to apply the proteolytic enzyme and any other powders first, merely by mixing it or them with the base particles including nonionic detergent, normally over a period of from one to 10 minutes, preferably from one to 5 minutes, and to post-add the perfume over similar periods of time, preferably as a spray, with the sprayed globules being of similar sizes to those described for the nonionic detergent. The free flowing spray dried product in which nonionic detergent has been absorbed is of a convenient higher bulk density than the usual spray dried detergent compositions and therefore is more convenient to use and requires less storage space. Although in some circumstances a limited proportion of phosphate, e.g. up to 10%, may be intentionally added to the compositions of the second preferred type, excellent detergency, with little or no deposition of residue onto washed items, is obtained without the use of any phosphate. The combination of carbonate and bicarbonate in the base beads is a buffered mixture which holds the pH of the product, at 0.07% concentration in wash water (J cup in a standard 64 litre washing machine tube of water), in the range from 8.5 to 11, preferably from 9 to 10.5. Such a pH is ideal for the action of any enzyme contained in the product and thereby helps to improve the washing and stain removing effect of the detergent compositions. Additionally, because during the spray drying operation some bicarbonate is decomposed to carbonate, carbon dioxide is released and localized areas in the product which may be of higher alkalinity are neutralized, helping to produce a more homogeneous bead, which may help to explain why the product is relatively compact, of high bulk density and highly absorbent. Also, because the bicarbonate does not decompose significantly in the crutcher but does change to carbonate during spray drying, which is effected in a short period of time, any other reactions with base bead components that can take place at higher pH are suppressed in the crutcher due to buffering by the bicarbonate and, if they are time reactions, do not take place appreciably during the spray drying despite the fact that the spray dried base beads, if dissolved in water, will usually have a somewhat higher pH than the crutcher mix.

When silicates are present having been spray dried with the base beads, as described, to the desired moisture content, the detergent composition resulting leaves little or no residue on washed laundry, unlike the situation which can prevail when various silicates are postadded or are included with zeolite-containing detergents in significant proportions similar to those employed in the compositions of the present invention.

As a result of the manufacturing process wherein silicate is added to a crutcher mix of water, carbonate and bicarbonate, possibly also with fluorescent brightener, pigment and other non-surface active constituents of the product, (but not with the nonionic detergent, proteolytic enzyme, perfume and other materials which it is best to postadd) until a gel or highly viscous crutcher mix is formed, after which addition is halted and the gel is destroyed or reduced in viscosity by application of shearing forces, and the balance of the silicate is added, and silicate and/or zeolite do not cause noticeable deposits on the washed laundry. Prior to the invention of the described method the full quantity of silicate would be mixed in the crutcher with other constituents, and although the crutcher mix might not thicken objectionably, the detergent compositions made would often objectionably deposit residue on washed items, especially if the amounts of silicate and zeolite were high. The reason for this is not understood at present, but one theory is that the destruction of the silicate gel releases more moisture in the crutcher mix to hydrate the zeolite satisfactorily, preventing the production of anhydrous zeolite and of combinations of zeolite and silicate which are more apt to deposit on the laundry during washing.

The various advantages are obtainable without extra materials or processing expenses, and the use of phosphate is avoided. Also, because detergents employed are nonionic they are less susceptible to interference from water hardness ions and other impurities and therefore the products are better washing agents under a wider variety of conditions, including cold water washing. Even in high hardness waters the compositions tend to disperse better any insoluble carbonates which may be formed. Finally, although carbonate in waste wash water entering the sewer and passing into inland waters is a source of carbon, required by living organisms, it is not nearly as likely to cause eutrophication of inland waters as is phosphate, in most circumstances, and accordingly, is more tolerable therein.

In a second preferred aspect of the invention there is made a product much like that of the first preferred aspect, with the major difference being in the absence of bicarbonate from the formula and the presence of hydrous sodium silicate. Like the . bicarbonate-containing product that of this inventive aspect is free flowing and of high bulk density and deposits little residue on the washed material.

In accordance with this second preferred type of . composition of this invention a free-flowing phosphate-ftee particulate heavy duty detergent composition is made which is of a bulk density greater than 0.6 g/ml, and which comprises a mixture of beads of ion exchanging zeolite and sodium . carbonate, with hydrous sodium silicate powder, in which the proportions of those components are in the ranges 1:0.1-1.5:0.1-0.3, having absorbed into them from about 0.2 to 1.0 or 1.5 parts of nonionic detergent, all such weights being on an anhydrous . basis. The nonionic detergent which is absorbed into the spray dried beads of zeolite and carbonate helps to hold the hydrous silicate in or on such beads.

A method for the manufacture of these composi25. tions comprises spray drying an aqueous mixture of zeolite and carbonate of a proportion in the range 1:0.1-1.5, mixing with the beads made from 0.1 to 0·3 parts of hydrous sodium silicate and absorbing into the mix from 0.2 to 1.5 or 0.2 to 1.0 parts of . nonionic detergent in liquid form.

The nonionic detergents, zeolites, carbonate, fillets, adjuvants and water employed are the same as those previously mentioned in the description of the first preferred type of compositions of the . invention.

The alkali metal carbonate will usually be particulate when added to an aqueous medium to form a crutcher mix with the zeolite and the particle sizes thereof will be within tha 20 to 200 mesh O.S.

. Sieve range, and preferably will be in the 100 to 200 mesh range. However, carbonate solutions may also be utilized. When sdlids are employed tney will usually be anhydrous but may be partially hydrated, too. Preferably the carbonate, usually . essentially pure sodium carbonate, will be over 95% pure and will not have any substantial proportion of bicarbonate present, such as may be considered to be present in sodium sesquicarbonate, Wegscheider1s salt or commercial products which are mixtures of . carbonates and biearbonates.

The water-soluble alkali metal silicate which is employed is that which is usually referred to as a hydrous alkali metal silicate, preferably sodium silicate of NagO’.SiOg ratio in the range of 1:1.5 to . 1:2.5, more preferably 1:1.8 to 1:2.4, e.g. 1:2.

Although it is possible to add such silicate to the aqueous crutcher with the carbonate and the zeolite when, in making the present detergent compositions, such procedure is followed objectionable deposits of . residues are sometimes noted on washed fabrics or other laundry, and because such deposits are to be avoided and it has been found that they can be substantially avoided by post-addition of hydrous alkali metal silicate, such post-addition method is normally utilized. In post-addition the hydrous sodium silicate, preferably in particulate or powdered form, usually With the particle sizes in the 10 to 200 mesh range, e.g. from 10 to 150 mesh, will be admixed with the spray dried base beads of zeolite and carbonate before spraying onto tumbling surfaces of such mixture the nonionic detergent in liquid form for sorption by the spray dried beads and, to some extent, by the hydrous silicate. Typical hydrous sodium silicate screen analyses (for Britesil H20 and Britesil H24'1) follow: 55% through No.10 sieve and on No. 48; 40% through 48, on 65; 4% through 65, on 100; and 3; through 100 on 150.

The proportions of active materials in the final product should be in the ranges 1 : 0.1 - 1.5 : 0.1-0.3 : 0.2 - 1.0 for zeolite : carbonate : silicate : nonionic detergent, respectively. Preferably, such proportions will be 1 : 0.2 - 1.0 : 0.15 - 0.25: 0.3 - 0.8, respectively. On a percentage basis, such constituents plus water are from 25% to 70% of synthetic zeolite, from 8% to 35% of sodium carbonate, from 5% to 15% of hydrous sodium silicate, from 15% to 25% of nonionic detergent and from 2% to 15% of water. Normally up to 10% of adjuvants, e.g. from 2% to 7%, are also present. Preferably such percentages will be from 30% to 60% of synthetic zeolite, from 8% to 30% of sodium carbonate, from 7% to 12% of hydrous sodium silicate, from 17% to 23% of nonionic detergent and from 5% to 12% of water. In a particular preferred formulation there are present, approximately, 45% of zeolite, 13% of sodium carbonate, 8.1% of hydrous sodium silicate, 20% of nonionic detergent, 2% of fluorescent brightener, 1.5% of proteolytic enzyme, 0.2% of pigment, 0.3% of perfume and 9.9% of water. The various ranges of adjuvant components will normally be about the same as those described with respect to the previous aspects of this invention. In the crutcher mix the percentages of components are usually from 20% to 60% of zeolite, from 5% to 30% of carbonate and from 25% to 60% of water, possibly with from 1% to 5% of adjuvants.

The high bulk density particulate heavy duty laundry detergent composition of this invention will usually be in free flowing rounded bead form such as that of other spray dried products, although the bead internal may be virtually honeycombed. The particle sizes of the beads will normally be in the range from 6 to 160 mesh, preferably 8 to 100 mesh, less than 10% preferably less than 5% and more preferably less than 1% of the product being outside such ranges. The bulk density of the finished detergent will normally be at least 0.6 g/ml, preferably at least 0.65 g/ml and most preferably in the 0.65 to 0.85 g/ml range, e.g. from 0.71 to 0.83 g/ml. the flow rates of such products are excellent and usually will be greater than 70% of the rate of free flowing sand of similar particle size, normally being from 70% to 95% thereof, preferably 75% to 95% thereof. Although the 0.65 to 0.85 g/ml bulk density range is Λ8186 preferred, by changing formulas and spray drying techniques it can be changed upwardly and downwardly, e.g. to 0.5 and 0.9 g/ml.

In the manufacture of the compositions of this second preferred aspect of the invention it is important that a sorptive bead be made for absorption of nonionic detergent therein. Such sorption should be sufficient for the nonionic detergent to pass into the bead interior so that it does not tend to cause caking of the beads or poor flow properties. While some forms of sodium carbonate have been found to be good sorbents for nonionic detergents (most are not), products made with the acceptable sorbent alone as the builder, at least in quantities needed to make compositions of the type which are acceptably detersive, tend to have objectionably high pH's. Even so, such products are not as free flowing as those of the present invention. For example, a sodium carbonate formerly sold by Diamond Shamrock Corporation, U.S.A., under the trademark Flozan could absorb 20% of nonionic detergent, yet Flozan-nonionic detergent mixtures were not as free-flowing as the present compositions. Also, because carbonate tends to precipitate out calcium and magnesium and other alkaline earth metal and heavy metal ions as insoluble compounds it may give rise to chalkiness in washed materials. However, when sodium carbonate is employed in a spray dried product, with synthetic zeolite of the type described, although both the carbonate and the zeolite components may be considered as separately tending to increase residue problems on washed fabrics, it is found that in the proportions described and with hydrous sodium silicate and nonionic detergent being post-added, the residue level is not objectionable. In other words, when the zeolite and carbonate are spray dried together in the proportions described, the product, which includes two materials each of which may develop residue problems, is found to be better than would be expected, with respect to residue deposition. Furthermore, the relatively small quantity of carbonate present reduces the toxicity of the product and diminishes the likelihood of oesophageal burns if the product should be accidentally ingested by infants.

In manufacturing the absorbent yet high bulk density spray dried detergent base beads, the spray drying operation is conducted in a normal manner, with only zeolite, carbonate, water and temperature-stable adjuvants, such as fluorescent brightener and pigment, normally being present. It is possible to spray dry a limited quantity of silicate, usually no more than 15% thereof, e.g. from 5% to 12%, together with the rest of the crutcher mix, but generally it is preferred to post-add hydrous sodium silicate instead. If silicate is spray dried with the rest of the base composition it is preferably a sodium silicate of NagOiSiOg ratio in the range from 1:2.0 to 1:2.5, e.g. about 1:2.4.

Whether or not the silicate is present in the crutcher mix, such mix will normally include from 48186 407o to 757ο of solids and from 257» to 60¾ of water. Preferably, the water content will be from 25% to 50 or 607o, the balance of the mix being non-surface active solids. The crutcher and spray drying . operations will usually be like those previously described, with the exception that bicarbonate will be omitted. Normally, silicate will also be omitted but if some is present and should thicken the mix objectionaoly during crutching it may be subjected . to high shear, as previously described.

Particle sizes of the final product may be regulated by controlling the spray drying conditions and the particle sizes of the powders post-mixed with the spray dried beads, but usually screening . after manufacture will also be employed to obtain the desired 6 to 160 or 8 to 100 sieve size ranges.

The advantages of compositions of this preferred second aspect of the invention and the method of manufacture are like those of the previously . described first preferred type. The combination of zeolite and a small quantity of carbonate, in conjunction with nonionic detergent and post-added hydrous sodium silicate (which also may be added after addition of the nonionic detergent) results in . a phosphate-free product which has detergency characteristics similar to phosphate-containing detergent compositions. The relatively small quantity of carbonate present keeps the alkalinity of the product low and maintains the wash water pH, . at normal use concentrations, in the range from 8.5 to 11, preferably 9 to 10.5. The product is usually of a higher density than the comparable product of the first preferred type which includes bicarbonate. Although such desirable effect may be 3· attributable to a higher percentage of zeolite present, it is surprising that a product with so high a zeolite content, with additional sodium carbonate (which is known to deposit on laundry when used in other compositions) does not produce · unacceptably high residue contents in washed laundry. Also, although it has been taught in the art that appreciable contents of silicates, whether post-added or co-spray dried with other portions of detergent compositions, are likely to produce · zeolite-silicate or other residues on washed laundry, with the present compositions it is found that any residues resulting are generally commercially acceptable and are not cause for rejection of the product by the consumers.

. The following Examples illustrate the invention.

All parts, percentages and other proportions herein are by weight and all temperatures are in °C unless otherwise stated. All mesh sizes herein are U.S. Sieve Series.

. EXAMPLE 1 Parts by Weight .

*Neodol 23-6.5 (Shell Chemical Company, U.S.A.) .0 **Molecular sieve zeolite 4A, crystalline, ultimate particle size of 4 to 8 microns (Union Carbide Corporation, U.S.A.) .0 EXAMPLE 1 (continued) Parts by Height Sodium carbonate 18.5 Sodium bicarbonate 14.0 Sodium silicate (NagOiSiOg = 1 : 2.4) 10.0 Tinopal 5BM” fluorescent brightener 2.0 Proteolytic enzyme 1.5 Ultramarine Blue pigment 0.2 Perfume 0.3 Water (including water of hydration of g g the zeolite, etc). 100.0 * Condensation product of fatty alcohol of an average of 12 to 31 carbon atoms with about 6.5 mols of ethylene oxide/mol.

** Anhydrous basis.

A free-flowing, high bulk density particulate detergent composition is prepared of the above formula and is of essentially globular particles, 99% of which are of sizes (usualtyconsidered as of diameters) in the range from 8 to 100 mesh. The product has a bulk density of 0.72 g/ml and flows at a rate of about 77% of that of dry sand of similar particle size, the standard for comparison. It is an excellent heavy duty synthetic organic detergent composition, useful for both hot and cold water washing of both synthetic and natural fibre textiles and it does not leave objectionable residues on such textiles, such as are often observed after washing with other synthetic detergent compositions wherein substantial proportions of zeolite (a water-insoluble inorganic builder) and silicate are employed together.

The product is made by admixing in a synthetic detergent or soap crutcher, at a temperature of 60°C (the water is initially heated and heat on the crutcher is maintained to reach and hold such temperature), zeolite, sodium carbonate and sodium bicarbonate, plus stable adjuvants such as pigment and brightener. The parts by weight employed are 25 of anhydrous zeolite, 11 of sodium carbonate, 22 of sodium bicarbonate, 0.2 of the pigment, 2 of the brightener and 55 of deionized water. Alternatively, tap water of low hardness, less than 50 ppm, as calcium carbonate, is substituted for the deionized water in some cases. After about 5 to 10 minutes of mixing, to the crutcher mix is added a 40% solids aqueous sodium silicate solution. After about 12 parts of such solution have been admixed, which takes about 4 minutes, the slurry becomes very viscous, with a viscosity, or of a thickness equivalent to a viscosity, of about 1,000 centipoises or more. During this mixing and that of the water, carbonate, bicarbonate, zeolite, pigment and fluorescent brightener prior to the addition of sodium silicate solution the mixer is set at a low speed, having a maximum mixing surface speed of about 5 metres/second. After formation of a thickened mix, high shear is applied over a period of about 6 minutes, wherein the shearing speed is about 35 metres/second, to break the gel and thin out the slurry, after which the balance of the silicate mixture is gradually added, again using the lower mixer speed previously employed. After completion of addition of such balance, which takes about 8 minutes, the crutcher mix is spray dried in a conventional countercurrent spray tower, which is about 10 metres high and 3 metres in diameter, by pumping it at a pressure of about ο kg/era gauge through an orifice about 1 ram in diameter into drying air (at a temperature of about 300°C inlet and 110°C outlet) so as to produce a product substantially in the 6 to 160 mesh range, which product is cooled to about room temperature and screened so as to be substantially all (over 99%) within such range. Alternatively, screening is effected to particle sizes in the narrower 8 to 100 mesh range. In both instances the base detergent composition beads made are of a high bulk density, about 0.6 g/ml and are free-flowing, such flow being about 80% or more of that of comparably sized dry sand.

Onto the base beads of 6 to 160 mesh size in an inclined drum blender are sprayed 20 parts of the Neodol 23-6.5 in liquid state at a temperature of about 30°C. The particles onto which the' Neodol 23-6.5 is sprayed as a mist, with droplet diameters of about 2 mm, are initially at a temperature of about 30°C (when normally solid nonionic detergent is used the temperature of the detergent is from 40° to 50°C and the bead temperature may be similarly elevated to prevent inmediate solidification of the sprayed-on nonionic detergent and to promote such detergent entering the internal pores of the base beads). Such spraying is effected within a period of about 8 minutes, after which the perfume is sprayed on and the proteolytic enzyme powder, of a particle size between 60 to 100 mesh, is dusted onto the surfaces of the particles, still in the mixing drum, each of which procedures takes about 3 minutes. The product is allowed to cool to 30°C after absorption of the nonionic detergent (if at a higher temperature) so as to avoid unnecessary loss of perfume components by evaporation.

The finished product, screened to 8 to 100 mesh size, is of the desired high bulk density and very good flow characteristics and is bottled, packed and warehoused, ready for shipment. When tested, it is found to be a satisfactory heavy duty detergent composition, useful for washing in both hot and cold waters, and, surprisingly, leaves little or no residue of zeolite and/or silicate or other materials on the washed fabrics. The product remains free-flowing during storage. It does not cake objectionably nor does it develop lazy flow characteristics. The pH of a 0,07% solution thereof in wash water is about 9.5, an ideal pH for proteolytic enzymatic action, which assists the detergent composition in cleaning and removing stains from washed fabrics, whether of synthetic (nylon, polyester and permanent press natural-synthetic blends) or natural fabrics (cottons).

When, instead of employing the spray drying process, the crutcher mix made is at a temperature in the higher end of the range given, e.g. at about 85°C, the water content is cut to the minimum for crutching, and spray cooling is employed to produce crystalline hydrates of the hydratable components of the crutcher mix, base particles are made which are treated with nonionic detergent in the manner previously described. However, absorption of the nonionic detergent is not as good, and the particles, containing more moisture and more unabsorbed nonionic detergent, are of poorer flow characteristics than the preferred product previously described. In another variation of the above experiment, when the silicate is omitted from the crutcher and is post-added as hydrous sodium silicate (“Britesil), either before of after addition of the nonionic detergent (before is preferred) a product is obtained which, while being a good heavy duty detergent composition, of high bulk density, in the range of 0.65 to 0.8 g/ml, and sufficiently free-flowing to be commercially acceptable, may not be as good as that of the Example with respect to leaving little or no residue on washed fabrics. Although the residue deposited may be acceptable in many cases, especially when the laundry is not dark coloured so as to make the ligher coloured residue easily apparent, still, residue deposition is objectionable in many instances and is. very preferably avoided completely. Λ* In a variation of the method of the main experiment of this Example the mixing operations are conducted using two different vertical mixers, one of which is of either the paddle or helix type and operates at slow speeds and the other of which is of a counterrotating shearing disc design and operates at high speeds. One or the other of the mixing elements is employed at a time, the other being removed from the mixer. The products made utilizing the combination of mixers rather than the same mixer at different speeds, are of essentially the same properties as that described above, but because of the increased shearing efficiency of the one mixer the processing proceeds faster, with a saving of from 2 to 6 minutes per batch.

Although, as indicated in the main portion of this Example, it is usual to post-add the nonionic detergent to the beads shortly after manufacture and also to post-add any other components of the product not in the spray dried base beads, this can also be done after ageing of the base beads for periods from 20 minutes to several days, without loss of their absorbing powers. In such cases it is desirable to heat the beads before application of the nonionic detergent, but by suitable choice of nonionic detergent type, with respect to melting point, this is avoidable.

EXAMPLE 2 Products of the formula given in Example 1 are made by utilizing different initial proportions of sodium carbonate and sodium bicarbonate and modifying drying tower conditions accordingly so as to cause more or less decomposition of sodium bicarbonate, e.g. »· from 10% to 70%. For example, instead of employing 22 parts of sodium bicarbonate and 11 parts of sodium carbonate, 18 parts of the bicarbonate and 15 parts of carbonate may be utilized while tower conditions (temperatures, hold-up time) are changed to diminish decom10 position of the bicarbonate. Of course, one may start with more bicarbonate, such as 25 parts, and less carbonate, e.g. 8 parts, and utilize increased tower hold-up times and higher temperatures to cause more severe decomposition of bicarbonate. In both such cases the finished product will be of essentially the same properties as that of a preferred embodiment of the invention described in Example 1. Similarly, such a product is obtained when, instead of utilizing the separate carbonate and bicarbonate components, the starting material employed is one wherein the two are mixed, as in the Snowlite products previously mentioned. Portions of the carbonate and bicarbonate contents or all of such contents may be from commercially available products such as the Snowlites, Wegscheiderite or sodium sesquicarbonate. Of course, with salts which include water of hydration, allowance will be made for the presence of such water as a component of the crutcher mix.

EXAMPLE 3 A crutcher formula for a product of high zeolite content is made by admixing 22.0 parts of sodium aluminium silicate (zeolite type 4A, Union Carbide Corporation U.S.A.), 15.2 parts of sodium bicarbonate (industrial grade), 7.6 parts of soda ash (natural), 14.2 parts of sodium silicate solution (47.5% solids content, Na20:Si02 ratio of 1:2.4), 0.1 part of Ultramarine Blue, 1.3 parts of “Tinopal 5BM Cone., 39.6 parts of water, and wet and dry remix in such quantity and proportion (q.s.) as to produce a crutcher mix containing 48.0% of solids. The base composition described is spray dried according to the method of Example 1, the moisture loss being 47.8% and the loss from bicarbonate breakdown to carbonate being 2.5% so that the yield is 49.7%. The product resulting, of particle sizes like those described for the products of Example 1, is post-blended with Neodol 23-6.5, proteolytic enzyme (Maxazyme P-375) and perfume, in respective proportions of 78.4, 20.0, 1.3, and 0.3 and the result is a product containing 26.9% (anhydrous basis) of zeolite, 10.6% of silicate solids, 13.4% of sodium bicarbonate (23.9% was added), 18.7% of sodium carbonate (12% was added), 20% of nonionic detergent, 1.3% of enzyme, 2% of fluorescent brightener, 0.2% of pigment, 6.6% of water and 0.3% of perfume. The cup weight is 155 g (the cup holds 240 ml), indicating a bulk density of 0.65 g/ml. Flowability is like that of the product of Example 1 and the product is similarly useful as a heavy duty laundry detergent composition, with properties like those described for the product of Example 1.

EXAMPLE 4 Parts by.Weight *Neodol 23-6.5 (Shell Chemical Company, U.S.A.) 20.0 **Molecular Sieve Zeolite 4A, crystalline, 45.0 ultimate particle size of 4 to 8 microns (Union Carbide Corporation, U.S,A.) Sodium carbonate 13,0 **Hydrous sodium silicate, Britesil, 8.1 manufactured by Philadelphia Quartz Company, U.S.A.

(Na20 : SiOg = 1 : 2.4) Tinopal 5BM fluorescent brightener 2.0 Proteolytic enzyme 1.5 Ultramarine Blue pigment 0.2 Perfume 0.3 Water (including water of hydration of zeolite, 9.9 silicate, etc.) 100.0 **Anhydrous basis A free-flowihg, high bulk density particulate detergent composition is prepared of the above formula and is of essentially globular particles, 99% of which are of sizes (usuallyconsidered as of diameters) in the range from 8 to 100 mesh. The product has a bulk density of 0.79 g/ml and flows at a rate about 91% of that of dry sand of similar particle size, the standard for comparison. It is an excellent heavy duty synthetic organic detergent composition, useful for both hot and cold water washing of both synthetic and natural fibre textiles and it does not leave objectionable residues on such textiles, such as may often be observed after washing with other synthetic detergent compositions wherein substantial proportions of zeolite insoluble inorganic builder and silicate are employed together, when employed at concentrations of from 0.05% to 0.15%, e.g. 0.07%, in wash water of medium hardness, e.g. 75 to 125 ppm, as calcium carbonate.

The product is made by admixing in a synthetic detergent or soap crutcher at a temperature of 60°C (the water is initially heated and heat on the crutcher is maintained to reach and hold such temperature) zeolite and sodium carbonate, plus stable adjuvants, such as pigment and brightener. The parts by weight employed are 55 of the zSolite (hydrated), equal to 45 parts of anhydrous zeolite, 13 of sodium carbonate, 0.2 of the pigment, 2 of the brightener. and of deionized water (plus 10 parts water in the zeolite). Alternatively, tap water of low hardness, less than 50 ppm, as calcium carbonate, is substituted for the deionized water in some cases. After about 20 minutes of crutching at a temperature of about 60°C the crutcher mix is spray dried in a conventional countercurrent spray tower, which is about 10 metres high and 3 metres in diameter, by pumping it at a pressure of about 25 kg/cm gauge through an orifice about 1 mm in diameter into drying air (at a temperature of about 300°C inlet and 110°C outlet) so as to produce a product of a moisture content of about 14% (removable at 105°C in 5 minutes), substantially, usually over 80%, in the 6 to 160 mesh range, which product is cooled to abou^room temperature (if above that) and screened so as to be substantially all (over 99%) within such range. Alternatively, screening is effected to particle sizes in the narrower 8 to 100 mesh range. In both instances the base detergent composition beads made are of a high bulk density, about 0.6 g/ml, and are free-flowing, such flow being about 80% or more of that of comparably sized dry sand.

With the base beads are blended about 10 parts of hydrous sodium silicate (8.1 parts of anhydrous silicate) of particle sizes in the 10 to 100 mesh range (to result in the formula quantity of silicate in the product) and after about 5 minutes mixing . there are sprayed into the mixture 20 parts of the Neodol 23-6.5 in liquid state at a temperature of about 35°C. The particles onto which the Neodol 23-6.5 is sprayed as a liquid mist, with droplet diameters of about 2 mm are initially at . room temperature (about 25°C). The spraying is effected within a period of about 8 minutes, after which the product is perfumed by spraying and the proteolytic enzyme powder, of a particle size between 60 and 100 mesh, is dusted onto the surfaces . of the particles, still inIhe mixing drum, each of which procedures takes about 3 minutes. The product is then allowed to cool to 30°C (if at a higher temperature) to prevent loss of perfume components by evaporation.

. The finished product, screened to 8 to 100 mesh size, is of the desired high bulk density and very good flow characteristics and is bottled, packed and warehoused so as to be ready for shipment. V/hen tested, it is found to be a satisfactory heavy duty , detergent composition, useful, for washing in both hot and cold waters, especially so at low concentrations, e.g. 0.0750 in wash water, and surprisingly, leaves little or no visible residue of zeolite and/or silicate or other materials on the washed fabrics.

. The product remains free-flowing during storage. It does not cake objectionably nor does it deveop lazy flow characteristics. The pH of a 0.15% solution thereof in wash water is about 9.8 and that of a 0.07% solution is about 9.5, ideal pH's for proteolytic enzymatic action, which assists the detergent composition in cleaning and removing stains from washed fabrics, whether of synthetic (nylon, polyester and permanent press natural-synthetic blends) or natural fabrics (cottons).

When the silicate is included in the crutcher mix instead of being post-added (a 40% solids content aqueous solution of Na20:Si02 ratio of about 1:2.4 is used instead of particulate hydrous silicate) an additional 5 minutes crutching time is taken to blend the silicate with the rest of the crutcher mix (it is added to the carbonate and water before addition of the zeolite and the water content of the silicate solution is taken into account in computing the amount of water to be added to the crutcher). The product obtained is a good heavy duty detergent composition of high bulk density and is sufficiently free-flowing to be commercially acceptable but is not considered to be as good as the previously described product of this Example.

In another variation of the experiment, the hydrous sodium silicate, in powder form, is admixed with the rest of the product and at least partially adhered to it after spraying onto such product of the nonionic detergent. The composition obtained, while acceptable, is not as good as that wherein the particulate hydrous sodium silicate is mixed with the zeolite first, prior to spraying onto the mix of the nonionic detergent. Flow properties are not as good, some caking on storage is noted and some segregation occurs.

Instead of employing the inclined drum for mixing and spray applications, when this is replaced by twin-shell, V- or Patterson Keeley type blenders, equivalent products are made.

Although, as indicated in the earlier portion of this Example, it is preferred to post-add the noniom'c detergent to the beads shortly after manufacture and also to post-add any other components of the product not in the spray dried base beads, this can also be done after ageing of the base beads for periods from 20 minutes to several days, without loss of their absorbing powers. In such cases it may be desirable to heat the beads before application of the noniom'c detergent but by suitable choice of nonionic detergent type, with respect to melting point, this is avoidable.

EXAMPLE 5 When in the methods and products of Example 4 the crystalline zeolite 4A is replaced by the corresponding amorphous material, which has an ultimate particle size (diameter) in the 0.01 to 0.05 micron range or when the hole in the zeolite is increased or decreased, while still being good for trapping hardness ions, to e.g. from 3 to 6 the composition obtained is of essentially the same flow and bulk density properties as that of the product of Example 4, is an excellent heavy duty laundry detergent which leaves no residue on washed clothing and sometimes is of even superior properties with respect to flow and absence of residue, compared to the crystalline product. This is also true but to a lesser extent when 50:50 amorphous : crystalline zeolite mixtures are employed. When type X zeolites are employed instead of type A such effects are also obtainable. Similarly, when type Y zeolites are utilized and other equivalents thereto, useful products are obtainable although they are not as good as those including the type A and/or X zeolites.

The products of this Example and of Example 4 are also useful 5 when the silicate is included partially in the crutcher and partially in the inclined drum mixer, e.g. half in each, preferably with the first being Na20 : SiOg of 1:2.4 silicate and the latter being hydrous sodium silicate of 1:2 ratio. Alternatively, although not preferably, the silicate and adjuvants may be omitted.

In addition to varying the type of zeolite present the types of silicates and nonionic detergent may be changed, as may be those of the various adjuvants. Thus, in the experiment of Example 4, instead of employing the hydrous silicate of Na20:Si02 ratio of 1:2, such ratio may be 1:1.8 or 1:2.2 and the products obtained are still like those previously described. Instead of utilizing Neodol 23-6.5“, Neodol 25-7 and Neodol 45-11, equally proportioned 2- and 3-component mixtures of such materials are employed. Instead of Tinopal 5BM, others of the previously mentioned fluorescent brighteners may be substituted or the brightener may be omitted entirely. „In the latter case the product obtained is of essentially the same detersive and physical properties, although desirable brightening of laundry is noticeably diminished in the absence of the fluorescent compound. In other variations of the method and products of Example 4 the proteolytic enzyme and the ultramarine blue are omitted from the formula. Alternatively, the colourant is employed in larger proportion to colour some product particles while others are uncoloured and beads of both types are mixed to produce a speckled version.

In addition to the various components listed others are also included, e.g., inert filler such as sodium sulphate, antiredeposition agents, such as sodium carboxymethylcellulose, antibacterial agents such as tetrabromosalicylanilide, laundry sweetening (and building) salts such as borax, and bleaching materials such as sodium perborate. The stable materials are usually preferably added in the crutcher whereas the others are post-added, either before or after spray-on of the nonionic detergent. When such materials are present in the described compositions, for example, 5% borax, % sodium sulphate, 0.5% sodium carboxymethylcellulose, 0.1% antibacterial compound and 10% sodium perborate, the product formula will be modified accordingly, preferably by proportional diminutions of zeolite, carbonate and silicate contents.

In place of the sodium salts of the various mentioned components, corresponding potassium or other suitable soluble salts, preferably alkali metal salts, are substituted, either in whole or in part, providing that the characteristics of the products obtained are acceptable and within the ranges given.

Claims (19)

1. A free-flowing, particulate, heavy duty, laundry detergent composition of a bulk density greater than 0.6 gm/ml which contains a water-soluble nonionic detergent absorbed into spray-dried beads 5. having a moisture content of 27, to 15% by weight and comprising a mixture of calcium ion exchanging zeolite of the empirical oxide formula (Na20) x -(Al

2. O3) y .(Si02) z .wH20 wherein x is 1, y is from 0.3 to 1.2, z is from 1.5 10. to 5.0 and w is from 0 to'9 and either sodium carbonate or a mixture of sodium carbonate and sodium bicarbonate in a weight ratio in the range of 3:8 to 5:1, with the proviso that the weight ratio on an anhydrous basis of zeolite to sodium carbonate 15. is in the range of 1:0.1 - 1.5 in the absence of sodium bicarbonate and the weight ratio of zeolite to sodium carbonate and sodium bicarbonate is in the range of 1:0.3 - 1.6:0.2 - 2.0, with the further proviso that spray-dried beads containing no sodium 20. bicarbonate are admixed with from 0.1 to 0,3 parts by weight on an anhydrous basis of particulate hydrous sodium silicate having an Sa2O:SiO2 mole ratio in the range of 1:1.5 to 1:2.5 prior to absorption of 0.2 to 1.6 parts by weight of said 25. nonionic detergent on the zeolite carbonatebicarbonate beads or 0.2 to 1.5 parts by weight of' said nonionic detergent on the mixture of zeolite-carbonate beads and particulate silicate to yield a composition containing 15% to 25% by weight of said nonionic detergent. 5. 2. A detergent composition according to Claim 1 which comprises beads of ion exchanging zeolite, sodium carbonate, sodium bicarbonate and nonionic detergent.

3. A detergent composition according to Claim 1 wherein the proportion of bicarbonate to carbonate is in the range from 1:2 to 2:1, the zeolite is a 15. type A zeolite of crystalline, amorphous or mixed crystalline and amorphous structure and the nonionic detergent is a higher fatty alcohol-polyethylene oxide condensate in which the higher fatty alcohol is of 10 to 18 carbon atoms and the polyethylene 20. oxide is of 3 to 30 mols of ethylene oxide per mol {> of higher fatty alcohol and the proportions of zeolite, carbonate, bicarbonate, and water are in the ranges from 15% to 40%, from 10% to 25%, from 8% to 22%, and from 2% to 10%, respectively. 25.

4. A detergent composition according to Claim 2 of bulk density in the range from 0.65 to 0.85 g/ml, of bead form of particle sizes in the range 6 to 160 mesh range (U.S. Sieve Series), and wherein said 30. spray dried beads further contain in addition sodium silicate of Na2O:SiO2 mole ratio in the range of 1:1.6 to 1:3.2 wherein the zeolite is of the molecular formula (Na 2 O)6·(A1 2 O 3 ) 6 .(SiO 2 )12-24·20-27 H 2 0 5. and the proportion of sodium silicate in the detergent composition is 3 to 20% by weight.

5. A detergent composition according to Claim 1 which comprises said mixture of spray-dried beads 10. containing ion exchanging zeolite, sodium carbonate and hydrous sodium silicate powder in which the proportions of said components are in the range from 1:0.1-1.5:0.1-0.3, and 0.2 to 1.0 parts of nonionic detergent are absorbed into them. 15.

6. A detergent composition according to Claim 5 wherein the said zeolite is a type A zeolite of crystalline, amorphous or mixed crystalline and amorphous structure, the said detergent is a higher 20. fatty alcohol-polyethylene oxide condensate in which the higher fatty alcohol is of 10 to 18 carbon atoms and the polyethylene oxide of 3 to 30 mols of ethylene oxide per mol of higher fatty alcohol, the proportion of zeolite to carbonate on an anhydrous 25. basis is within the range 1:0.2-1.0 and the said weight percentages of zeolite, carbonate, silicate and water present are in the ranges 25% to 70%, 8% to 35%, 5% to 15% and 2% to 15%, respectively. 30. 7. A detergent composition according to Claim 6 of bulk density in the range from 0,65 to 0.85 g/ml and of bead form of particle sizes in the range from 6 to 160 mesh U.S. Sieve Series, wherein said 5. hydrous sodium silicate particles have a size in the 100 to 200 mesh U.S. Sieve Series range and ate ' adhered to other components thereof, said zeolite is of the molecular formula (Νβ2θ)6·(Αΐ2θ3>6·(SiO2)12-24·20-27 HgO 10. and said nonionic detergent is a condensation product of a higher fatty alcohol of 12 to 18 carbon atoms and 5 to 12 mols of ethylene oxide pet mol. 8. A method of manufacturing a free-flowing 15. particulate heavy duty laundry detergent composition of a bulk density greater than 0.6 g/ml which comprises the steps of spray drying a mixture of calcium ion exchanging zeolite of the empirical formula 20. (Ua20) x .(Al2O3)y.(Si02) z .w H2O wherein x is 1, y is from 0.8 to 1.2, z is from 1.5 to 3.5 and w is from 0 to 9, water and sodium carbonate or sodium carbonate and sodium bicarbonate a to a moisture content in the range of 2% to 15% so 25. that the proportion by weight in the spray dried beads of zeolite to sodium carbonate is in the range 1:0.1-1.5 on an anhydrous basis or to sodium carbonate plus sodium bicarbonate is in the range 1:0.3-1.6:0.2-2; mixing with the beads, when sodium 30. bicarbonate is omitted, from 0.1 to 0.3 parts by

7. A detergent composition according to Claim 6 of bulk density in the range from 0.65 to 0.85 g/ml and of bead form of particle sizes in the range from 6 to 160 mesh (J.S. Sieve Series, wherein said 5. hydrous sodium silicate particles have a size in the 100 to 200 mesh J.S. Sieve Series range and are adhered to other components thereof, said zeolite is of the molecular formula (Na2O)6.(Al2Ο3)6·(SiO2)12-24· 20-27 H 2° 10. and said nonionic detergent is a condensation product of a higher fatty alcohol of 12 to 18 carbon atoms and 5 to 12 mols of'ethylene oxide per mol.

8. A method of manufacturing a free-flowing 15. particulate heavy duty laundry detergent composition of a bulk density greater than 0.6 g/ml which comprises the steps of spray drying a mixture of calcium ion exchanging zeolite of the empirical formula 20. (Na 2 0) x . (Al 2 0 3 ) y . (SiO 2 ) z .w II 2 O wherein x is 1, y is from 0.8 to 1.2, z is from 1.5 to 3.5 and w is from 0 to 9, water and sodium carbonate or sodium carbonate and sodium bicarbonate to a moisture content in the range of 2¾ to 15% so 25. that the proportion by weight in the spray dried beads of zeolite to sodium carbonate is in the range 1:0.1-1.5 on an anhydrous basis or to sodium carbonate plus sodium bicarbonate is in the range 1:0.3-1.6:0.2-2; mixing with the beads, when sodium 30. bicarbonate is omitted, from 0.1 to 0.3 parts by weight of particulate hydrous sodium silicate having an Na20:Si02 mole ratio in the range of 1:1.5 to 1:2.5 and mixing either 0.2 to 1.5 parts by weight of water soluble nonionic detergent .with the mixture 5, of zeolite-carbonate particulate beads and hydrous sodium silicate or 0.2 to 1.6 parts by weight of said nonionic detergent with said zeolite-carbonatebicarbonate beads, said nonionic detergent being in liquid form so the nonionic detergent is absorbed 10. into the beads, to produce a composition containing 15% to 25% by weight of said nonionic detergent.

9. A method according to Claim 8 wherein the spray drying is of an aqueous mixture of said 15. zeolite, sodium carbonate, sodium bicarbonate and water which is spray dried to a moisture content in the range from about 2% to 12%, so that the proportions of zeolite, sodium carbonate and sodium bicarbonate in the spray dried beads produced are in 20. the ranges 1:0.3-1.6:0.2-1.5, on an anhydrous basis, and from 0.2 to 1.6 parts of nonionic detergent in liquid form is mixed with said spray dried beads.

10. A method according to Claim 9 wherein said 25. ion exchanging zeolite is a synthetic sodium aluminosilicate, said nonionic detergent is a higher fatty alcohol-polyethylene oxide condensate in which the fatty alcohol is of 10 to 18 carbon atoms and the polyethylene oxide is from 3 to 30 mols of ethylene 30. oxide per mol of higher fatty alcohol, the aqueous - 48186 mixture that is spray dried includes from 10% to 35% of synthetic zeolite, from 5% to 20% of sodium carbonate, from 10% to 30% of sodium bicarbonate and from 25% to 60% of water, the proportion of 5. bicarbonate to carbonate being in the range from 1:1 to 4:1 in the aqueous mixture and within the range from 1:2 to 2:1 in the spray dried beads.

11. A method according to Claim 10 wherein the 10. bulk density of the product is in the range from 0.65 to 0.85 g/ml, the aqueous mixture which is spray dried includes, in addition, 2% to 15% of water-soluble sodium silicate having an NagCHSiOg mole ratio in the range of 1:2 to 1:3 so that the 15. spray dried product contains from 3% to 20% thereof, the zeolite is a type A zeolite of crystalline, amorphous or mixed crystalline and amorphous structure and the nonionic detergent is a condensation product of a higher fatty alcohol of 12 20. to 15 carbon atoms and 5 to 12 mols of ethylene oxide per mol and said aqueous mixture of zeolite, carbonate, bicarbonate, silicate and water is a crutcher mix made by making a slurry of water, sodium carbonate and sodium bicarbonate, admixing 25. with such a mixture sodium silicate until a gel is obtained, shearing the gel to reduce the viscosity thereof and admixing with the sheared mixture additional silicate to the desired concentration thereof.

12. A method according to any of Claims 8 to 10 wherein the zeolite is crystalline and is of the claimed molecular formula (Na2O)6.(Al203)5.(Si02)i2-24-w H 20 5. wherein w is from about 15 to 27, mixing is carried out in a crutcher at a temperature in the range from 20 to 70°C, spray drying is effected in a spray tower by drying air at a temperature in the range from 150 to 350°C, the crutcher mix is atomized by 10. being forced through a circular nozzle of internal diameter in the range from 0.5 to 2 mm at a pressure in the range.from 10 to 50 kg/cm^ gauge, the spray dried product is screened to sizes in the range from 6 to 160 mesh (U.S. Sieve Series) and said nonionic 15. detergent is a condensation product of a higher fatty alcohol of 12 to

13. Carbon atoms and about 6.5 mols of ethylene oxide per mol and is applied to the spray dried particles as they are tumbled in a tumbling drum by spraying it in a liquid state at a 20. temperature in the range from 20 to 70°C onto the moving surfaces of the spray dried particles to produce particles of sizes in the 6 to 160 mesh (U.S. Sieve Series) range. 25. 13. A method according to Claim 8 which comprises spray drying an aqueous mixture of calcium ion exchanging zeolite, sodium carbonate and water and mixing with the beads from 0.1 to 0.3 parts of said hydrous sodium silicate in particulate form and 30. mixing with said mixture of spray dried beads and particulate hydrous sodium silicate, the said nonionic detergent in liquid form, all parts being as anhydrous materials, so that the detergent is absorbed into the beads. 5.

14. A method according to Claim 13 wherein the ion exchanging zeolite is a synthetic sodium aluminosilicate, the nonionic detergent is a higher fatty alcohol-polyethylene oxide condensate in which the 10. fatty alcohol is of 10 to 18 carbon atoms and the polyethylene oxide is of 3 to 30 mols of ethylene oxide per mol of higher fatty alcohol, the aqueous mixture that is spray dried includes from 20% to 60% of synthetic zeolite, from 5% to 30% of sodium

15. carbonate and from 25% to 60% of water, and the proportion of zeolite to carbonate is in the range 1:0.2-1.0 in the aqueous mixture and in the end product. 20. 15. A method according to Claim 14 wherein the bulk density of the product is in the range from 0.65 to 0.85 g/ml, the zeolite is a type A zeolite of crystalline, amorphous or mixed crystalline and amorphous structure, the nonionic detergent is a 25. condensation product of a higher fatty alcohol of 12 to 15 carbon atoms and 5 to 12 mols of ethylene oxide per mol, the hydrous sodium silicate is of Na20:SiC>2 mole ratio in the range 1:1.8 to 1:2.4, the hydrous sodium silicate is admixed with the 30. spray dried base beads in such proportion that the final product contains from 5% to 15% thereof.

16. , A method according to any of Claims 13 to 15 wherein the zeolite is crystalline and is of the molecular formula (Na20)g.(Αΐ2θ3)6·(Si02)i2-24’ w Η 2θ 5, wherein w is from 15 to 17, mixing is carried out in a crutcher at a temperature in the range from 20 to 70°C, spray drying is effected in a spray tower by drying air at a temperature in the range from 150 to 350°C, the crutcher mix is atomized by being forced 10. through a circular nozzle of internal diameter in the range from 0.5 to 2 mm at a pressure in the range from 10 to 50 kg/cm^ gauge, the spray dried product is screened to sizes in the range from 6 to 160 mesh, U.S. Sieve Series, the nonionic detergent 15. is applied to the mixture of particulate hydrous silicate and spray dried particles as it is tumbled in a tumbling drum by spraying the nonionic detergent in a liquid state at a temperature in the range from 20 to 70°C onto the moving surfaces of 20. the mixture to produce particles of sizes in the Nos. 6 to 160 mesh, U.S. Sieve Series, range.

17. A method according to Claim 8, substantially as described in any of Examples 1 to 5. 25.

18. A free-flowing particulate heavy duty laundry detergent composition of a bulk density greater than 0.6 g/ml which has been manufactured by a method according to any of Claims 8 to 17. 30.

19. - A laundry detergent composition as claimed in Claim 1 and substantially as described in any of the Examples.