WO1994005767A1

WO1994005767A1 - Detergent composition and process for its production

Info

Publication number: WO1994005767A1
Application number: PCT/EP1993/002340
Authority: WO
Inventors: William Martin Karpusiewicz; Andra Joy Goldman; Feng-Lung Gordon Hsu; Charles Fraser Irwin
Original assignee: Unilever Plc; Unilever Nv
Priority date: 1992-09-08
Filing date: 1993-08-28
Publication date: 1994-03-17
Also published as: CA2143869C; EP0659208A1; CA2143869A1; JPH08501118A; AU688277B2; AU4955393A; BR9307023A

Abstract

Detergent powders of high bulk density, containing anionic and nonionic surfactant and builders are prepared by spray-drying a low moisture content slurry containing liquid active surfactants to suspend inorganic solids including selected builders. A viscosity adjuster may be added to improve processability.

Description

DETERGENT COMPOSITION AND PROCESS FOR ITS PRODUCTION

Technical Field of the Invention This invention relates generally to a process for the

production of detergent powder by spray-drying.

Background Traditional mixed active builder containing slurries utilize water as the carrier system for both the active (e.g.

surfactant) and solids (e.g. builders such as zeolite, carbonate, and the like). This usually results in high slurry moisture content (i.e. 40-50%).

Liquid active blends on the other hand allow for water and active together to act as a carrier for the solids. The active has changed its function in the slurry. The active instead of being a "solid additive" which must be suspended in the liquid water carrier has itself become part of the liquid carrier system. This change allows for a reduction in the amount of water needed in the slurry as a carrier, because the active substitutes for part of the water. In the spray-drying process there are frequently opposing factors; for example, more water present in a slurry, requires more evaporation, with a resultant increase in costs. If less water is used to save costs, the slurry becomes correspondingly more viscous until a point is reached at which it cannot be pumped and metered. An additional factor, due to market considerations is that the finished product requires higher quantities of surfactant. Spray-drying, for example, increased quantities and certain types of nonionic surfactant lead to pluming from the spray tower. High temperatures contribute to this pluming. Generally other things being equal, spray-drying of a slurry having a lower water content leads to less heat input in the tower than higher water content. It is thus desirable to be able to spray-dry low water content slurries while minimizing the problem of high slurry viscosity. A further advantage is that high density powders may be thus obtained.

U.S Patent 4,738,793 employs low moisture slurries for spray-drying but this is accomplished using nonionic surfactants in the substantial absence of anionic surfactant (less than 2% anionic is taught).

The current art describes the use of high shear mechanical devices to achieve high powder density (>600 g/L) with zeolite layering to control particle size distribution of the final product U.S. 4,869,843. Also described in use of nonionic surfactant sprayed onto base powder with addition of secondary materials to achieve high powder density (>450 g/L). U.S. 5,030,379 to Knight et al. Specific preparative methods for low water content compositions are disclosed in U.S. 5,075,041.

The method employed by the art for lowering slurry moisture and avoiding pluming from high temperatures or high nonionic concentrations have not been completely satisfactory.

Definition of the Invention

A method of slurry preparation and a slurry composition which exhibits exceptionally low viscosity even at low water content, thus enabling it to be spray-dried to a high

surfactant concentration without unacceptable pluming has now been discovered. In addition, it has been found that a spray-dried powder of exceptionally high density can be obtained. Simple mixtures of water and nonionic surfactant, typically result in a very viscous gel. Gel formation may be avoided in producing a liquid active mixture by using a preferred order of addition: water plus caustic, then nonionic plus the acidic form of the anionic surfactant. Water plus caustic changes the characteristic viscosity curve so that when the nonionic is added an emulsion is formed in place of a gel. Emulsion viscosity, of course, is much less than gel

viscosity. The acid precursor of the anionic may then be added and is preferably neutralized in situ. This makes the liquid active mixture more viscous, but still avoids the gel state. Once this is done, solids addition of the builder, i.e. zeolite and/or carbonate as well as other builders such as NTA and the like may be carried out.

In U.S. Patent No. 4, 923, 636 Blackburn and U.S. Patent No. 4, 826, 632 Blackburn, there are disclosed liquid surfactant compositions that can be sprayed onto spray-dried powders to increase the bulk density thereof. While these 'densified' spray dried powders have not been produced by mechanical densification, the disadvantages of using a spray dried powder as a starting point remain.

A blend of surfactants may be used such as that disclosed in Hsu er al. Serial Number 07/808,314 filed 12/16/91 or

07/816,366 filed 12/31/91. In the blend, in addition to a neutralized or partially neutralized anionic surfactant, nonionic surfactants are included. A low moisture content detergent slurry is manufactured utilizing liquid active surfactant blends containing anionic and nonionic surfactants. This low moisture slurry is then spray-dried using standard spray-drying techniques yielding, if desired, a concentrated or high density base powder.

Accordingly, the invention provides a process for preparing by spray-drying, washing powders containing anionic active, nonionic active and builder, i.e., carbonate and zeolite, for example, crystalline and/or amorphous aluminosilicate

including the zeolites disclosed in EP,384,070A and 448,297A. The builders are used in a proportion of at least about 5 to 50 percent of anionic to 1 to 50 percent of nonionic to 5 to 70 percent of a builder.

The slurry is prepared by forming an aqueous mixture of a nonionic and anionic surfactant to which a builder and other detergent components may be added to produce the slurry for spray-drying. The aqueous anionic-nonionic mixture comprises water, a nonionic active and an anionic active wherein the anionic is incorporated as: i) the acid form of an anionic surfactant and the mixture further contains a neutralising agent whereby the acid is neutralised in situ to form the anionic surfactant; and/or; ii) an anionic surfactant.

Where the anionic surfactant is incorportaed into the mixture as a surfactant preferably the nonionic and anionic

surfactant are mixed to form a surfactant blend which is then incorporated into the mixture. Suitably preparation of the slurry in which the surfactants are incorporated as a blend is comprised of: A. preparing under agitation a mixture of water, optionally a viscosity adjuster, optionally sufficient alkali metal hydroxide to result in neutralization of the acidic form of desired adjuvants and a prepared surfactant blend containing anionic and nonionic surfactants thus forming an anionic nonionic active mixture, said blend containing about 10% to 80% anionic surfactant, and 0% to 35% water;

B. preferably maintaining the temperature of said mixture below about 200°F;

C. then adding under sufficient agitation to said anionic-nonionic mixture, sufficient builder and other detergent adjuncts such as sodium silicate, polymer, and the like to result in said powder containing about 5% to 70% of a builder selected from the group consisting of zeolite, carbonate and mixtures thereof. Other builders such as sodium citrate may also be added. This combination of ingredients forms a final slurry mixture having a maximum amount of about 35% water, the minimum amount of water being sufficient to achieve appropriate viscosity;

D. optionally adding a viscosity adjuster, in an amount of from 0 to 50% of said mixture, at any time during the slurry process to result in a viscosity of the final slurry mixture of about 1000 to 20,000 cps measured at a shear rate of 17 to 18 sec^-1 and a temperature of 150° to 195°F.

E. then adjusting the temperature, if necessary, of said final mixture to about 135-195°F and spray-drying said final mixture to form the base powder;

Suitably preparation of the slurry in which the anionic surfactant is incorporated in the acid form is comprised of:

A. preparing under agitation a mixture of water, optionally a viscosity adjuster and sufficient alkali metal hydroxide to result in neutralization of the acidic form of said anionic active and optionally other anionic additives, e.g., citric acid; B. adding under said agitation to said mixture, sufficient nonionic active to prepare said powder, said powder having a range of about 1% to 50% by weight nonionic, thus resulting in a nonionic active mixture;

C. adding under agitation, to said nonionic active mixture a sufficient amount of the acidic form of said anionic active to result in a final powder containing about 5% to 50% of the salt form of said anionic active, thus forming an anionic-nonionic mixture;

D. preferably maintaining the temperature of said mixture below 200°F; E. then adding under sufficient agitation to said anionic-nonionic mixture sufficient builder and other detergent adjuncts such as sodium silicate, polymer, and the like to result in said powder containing about 5% to 70% of a builder selected from the group consisting of zeolite, carbonate and mixtures thereof. Other builders such as sodium citrate may also be used. This combination of ingredients forms a final slurry mixture having a maximum amount of 35% water, the minimum amount of water being sufficient to achieve

appropriate viscosity;

F. optionally adding a viscosity adjuster, in an amount of from 0 to 50% of said mixture, at any time during the slurry process to result in a viscosity of the final slurry mixture of about 1000 to 20,000 cps measured at a shear rate of 17 to 18 sec^-1 and a temperature of 150° to 195°F.

G. then adjusting the temperature of said final mixture to about 135-195°F and spray-drying said final mixture; DESCRIPTION OF THE INVENTION

Preferably the water content will be from 10% to 40% by weight of the slurry, in which case it will be possible to spray-dry the powder to a bulk density above 500 g/liter, desirably from 500 to 900 g/liter. Generally, it will be preferred to reduce the water content to the minimum

practical level, although the percentage at which this minimum occurs will vary with the content of the other components of the formulation as explained in more detail below.

Viscosity is extremely important since for ease of operation any composition, e.g. a slurry, must be capable of being sprayed at pressures commonly used such as 10 psi to 1000 psi through nozzle sizes of about 0.1 mm to 11 mm or more at temperatures of about room temperature of about 65°F up to about 200°F. Such low temperatures avoid excess evaporation. Typically, the viscosity of such composition is about 1000 centipoise to 20,000 centipoise at a temperature of 150° to 185°F or even somewhat higher at a shear rate of 17 to 18 sec^-1.

Compositions having a ratio of anionic surfactant to nonionic surfactant of 1:3 to 3:1 may be employed but 1:2 to 2:1 are of especial interest.

Preferably, the composition of slurry should be formulated so that the viscosity of the final slurry is about 7,000 to 20,000 cps, preferably less than 20,000 centipoise, more preferably less than 10,000 centipoise, measured at a shear rate of 17 to 18 secs^-1 at a temperature of 150° to 185°F. The slurry must be sufficiently fluid to allow thorough mixing of all of the components in the mixer. After mixing is finished, the slurry must remain sufficiently fluid to pump it out of a mixing vessel to a spray tower. As better and more efficient mixers become available processing of more viscous systems becomes easier. Conversely, as pumps are improved, higher viscosity slurried can be pumped. The viscosity must be such that the desired physical mixing and pumping can be done economically and chemical reactions if any, such as neutralization take place readily. The final point prior to spray-drying is the actual atomization of the slurry in the tower spray nozzles. There are many different designs of spray nozzles well known to those skilled in the art with which to achieve appropriate atomization.

Liquid mixing can be defined as a Reynolds number (N_Re) where N_Re is defined as follows:

where N_Re is Reynolds Number, N is impeller speed, D is impeller diameter, p is specific gravity and μ is viscosity at a shear rate of Nπ sec^-1. in order to provide appropriate impeller mixing, the final slurry in the mixer should have a flow with a Reynolds Number of about 1 to 10,000 which is conveniently produced by an appropriate impeller design.

VISCOSITY ADJUSTERS

The viscosity of the slurry thus depends upon many functional parameters. The viscosity to be achieved must be appropriate for the slurry to be mixed, pumped and atomized in a spray tower. The viscosity thus may vary within fairly wide ranges. The viscosity of the slurry can be adjusted by the addition of an organic or inorganic additive in a sufficient amount to result in a viscosity in the final slurry of about 1000 to 20,000 cps at a shear rate of 17 to 18 sec^-1 and a temperature of 150° to 185°F. Examples of viscosity adjusters are nonionic surfactants, hydrotropes (e.g., sodium xylene sulfonate), polyethylene glycol, polypropylene glycol and inorganic salts (e.g., Na₂SO₄). This viscosity adjuster may be introduced into the water at the beginning or optionally during the process or may even be added after the anionic precursor but it is preferably added prior to most of the zeolite or other builder solids to insure proper fluidity. The viscosity adjuster may also be put into any of the additives as a mixture and added in this way.

The amount of viscosity adjuster employed is sufficient to insure slurry fluidity and varied from about 0.5% of the slurry weight to about 30% of the slurry weight. It also must be realised that when an anionic sulfated or sulfonated precursor is prepared, a certain amount of free or acidic sulfate will be formed. Due to these impurities in the precursor, some sulfate salt will be present. In normal commercial products, this is usually insufficient to fully fluidize the slurry. Of course, if excess sulfuric or other acid were added intentionally to the precursor, or if the sulfonation or sulfation reaction forming the precursor were terminated prematurely sufficient sulfate or other anion could be introduced with the precursor and the salt formed in situ to fluidize the slurry without adding excess viscosity adjuster.

Temperature during the processing should be carefully

controlled. Temperatures of 200°F or more have destabilized the slurry and degraded the components. NONIONIC

It is essential to the successful application of the process of the invention that the slurry should contain a nonionic surfactant. Preferably the nonionic surfactant will be an ethoxylated or ethoxylated propoxylated primary or secondary linear or branched chain alcohol having a carbon chain length in the hydrophobic portion of from 5 to 25, and containing from about 5 to about 35 moles of ethylene/oxide and/or propylene oxide per mole of alcohol. Examples of such materials are ethoxylates the Dobanol and Neodol (Registered Trade Mark) alcohols, sold by Shell Chemicals and the

Tergitol (Registered Trade Mark) ethoxylated alcohols sold by Union Carbide Corporation. However, other types of nonionic surfactants can also be used, alkyl phenol ethoxylates for example, including in particular the reaction products of alkylene osices, usually ethylene oxide, with alkyl (C₆-C₂₂) phenols, generally 5-25 EO, i.e. 5-25 units of ethylene oxide per molecule; and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylene diamine. Other so-called nonionic surfact-actives that may be used include alkyl polyglycosides, long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides.

The amount of nonionic in the final powder will be about 5 to 50%, preferably 10 to 30%.

ANIONIC

Anionic surfactants which may be formed from precursors (e.g., sulfonic acids) are also essential.

Typical anionic surfactants include sodium alkylbenzene sulphonates, sodium alkyl sulphates, sodium alkane sulphonates and sodium alkyl ether sulphates. More

particularly, C₈-C₂₄ primary and secondary alkyl or alcohol sulfates C₈-C₂₄ secondary alkane sulfonates, C₈-C₂₄ olefin sulfonates, C₁₀-C₂₂ soaps and the like may be employed, preferably, sodium or potassium alkylbenzene sulfonates or alkyl sulfates are employed. Particularly suitable

alkylbenzene sulfonates are sodium C₁₁-C₁₅ alkylbenzene sulfonates. Suitable alkyl sulfates are C₁₁-C₁₅ alkyl

sulfates, although other alkyl sulfates and sulfonates outside this carbon chain length range, may also be used.

The acid form of the precursor is neutralized in the mixture with sodium, potassium or ammonium hydroxide.

The amount of anionic in the final powder will be about 5 to 50%, preferably about 10 to 40%.

BLENDS

In addition to the use of individual actives as discussed above, prepared liquid active blends of nonionic and anionic surfactants may be used. These blends and methods for their preparation and use are disclosed in U.S. Patents 4,637,891; 4,826,632; 4,923,636; 5,045,238; 5,075,041 as well as EP 88,612A and 0,265,203; French patent 2,645,876 and GB Patent 1,169594. These blends may be employed with the instant invention, particularly those disclosed in U.S. patents 4,826,632 and 4,923,636 and Serial Numbers 07/808,314 filed 12/16/91 adn 07/816,366 filed 12/31/91 to Hsu et al. hereby incorporated by reference herein.

The method of preparation of the blend is important. Simple admixture of normally 50% aqueous neutralized alkylbenzene sulphonate paste and liquid nonionic surfactant in the desired proportions will give not a mobile isotropic liquid but a highly viscous gel which is difficult to handle. Liquid nonionic surfactant may be gradually added to an alkylbenzene sulphonate paste (neutral salt) which will typically have an active matter content of about 50% by weight. The resulting viscous material, containing more than 10% water, is then heated to a sufficiently high temperature for a sufficient period of time for the water content to fall below 10% by evaporation. A clear mobile liquid is obtained and this remains clear and mobile when allowed to cool to ambient temperature.

According to a second method, alkylbenzene sulphonic acid may be mixed with nonionic surfactant, and the mixture treated with concentrated aqueous sodium hydroxide or potassium hydroxide to effect partial or complete neutralization.

Mixtures fluid at 20° to 80°C and containing about 6 to 7% by weight of water may be produced by this method.

According to a variant of the second method, the alkylbenzene sulphonic acid starting material may be in partially

neutralized form.

In a third method, a range of compositions containing anionic surfactant, nonionic surfactant and water in relatively high amounts up to about 35% may be prepared containing sodium or potassium hydroxide in excess of that necessary to neutralize the anionic sulfonic acid if a precursor is used. These compositions are sufficiently mobile at temperatures no higher than about 90°C. The blends employed are liquid surfactant compositions mobile at a temperature within the range of about 15° to 90°C or if the anionic to nonionic ratio is appropriate and the type of nonionic is appropriate even down to about 5°C. This composition contains

preferably; (a) a sodium or potassium salt of an alkylbenzene sulfonate or alkyl sulfate in an amount not exceeding 80% by weight and preferably 5 to 80% or even 20% to 60% by weight, (b) an ethoxylated nonionic surfactant in an amount not exceeding 80% by weight, preferably 5 to 80% and most

preferably 20% to 60% by weight,

(c) sodium or potassium hydroxide in an amount of about 2% to 15% by weight, depending on the ratio of anionic to nonionic. For very high anionic to nonionic ratios of 2:1 up to 4:1 a greater excess of caustic is preferred whereas for lower ratios of 0.125:1 smaller excess amounts such as 2% are sufficient, and

(d) water in an amount of 0%-35% by weight preferably 5% to 20% by weight most preferably about 10% up to about 20% by weight. Higher water contents, that is, contents greater than about 10%, when included in a composition of anionic and nonionic surfactants typically result in gel formation even with low ratios of anionic to nonionic such as 0.125:1. The addition of concentrated aqueous hydroxide solution (50 w/w%) prevents gel formation and reduces the viscosity of the composition even though water is added to the composition by the

introduction of the aqueous hydroxide solution. The ability to increase the water content of such compositions greatly expands the operation window. The reduction of the viscosity facilitates the ease of operation by improving pumpability and the like.

Viscosity of the blend is extremely important since for ease of operation any composition must be capable of being processed. Typically, the viscosity of such compositions is about 50 centipoise to 5000 centipoise at a temperature of 60°C or even somewhat higher.

Compositions having a ration of anionic surfactant to

nonionic surfactant of 0.125:1 to 4:1 may be employed but 1:1 to 3:1 are of especial interest.

In addition, an improvement with regard to the processability properties may be obtained in the blend if 0.5-80% by weight of a C₈-C₂₂ fatty acid is incorporated in the liquid

surfactant composition.

In this case, the blend provides a liquid surfactant

composition which is mobile at a temperature within the range of 20 to 80°C and which comprises a sodium or potassium salt of an alkylbenzene sulfphonate or alkyl sulphate in an amount preferably not exceeding 70% by weight; an ethoxylated nonionic surfactant in an amount preferably not exceeding 80% by weight; and water in an amount preferably not exceeding 20% by weight, more preferably not exceeding 10% by weight; characterized in that it further comprises 0.5 to 80% by weight of a fatty acid having 8 to 22 carbon atoms.

According to yet another aspect of the invention, there is provided a process for the manufacture of the above liquid surfactant composition, by mixing said nonionic surfactant with a concentrated aqueous alkali metal hydroxide solution having about 80% to 98% of the stoichiometric amount of said alkali metal hydroxide necessary to neutralize an acid precursor of said sulphate or sulphonate, to form a nonionic alkali dispersion; mixing said acid precursor with said dispersion form a blend; adjusting the pH to about 7; and then mixing the blend with the fatty acid to form the mobile composition. The compositions include in addition 0.5-70%, preferably 2-15%, more preferably 2-7% by weight of a fatty acid having 8 to 22 carbon atoms. It is preferred if the fatty acid possesses 12 to 20 carbon atoms, and more in particular 16 to 18 carbon atoms. A suitable fatty acid is coconut fatty acid.

BUILDERS Selected builder materials are added to the slurry. The builders are preferably zeolite and/or sodium carbonate.

Other substantially solution materials which have a

detergency builder action may be used by including them in the slurry. Of course, these builders may be added by post dosing to the composition produced by the spray-drying step. Examples of substantially soluble detergency builders are sodium tiproly-, pyro- and orothophosphates, sodium citrate and various organic detergency builders such as sodium nitrilotriacetate, ODS; TMS/TDS homopolymers of acrylic acid and copolymers of acrylic and maleic acids. Substantially insoluble builders are, for example, sodium aluminosilicates including zeolites, crystalline, amorphous, as well as calcite, and the like. Generally detergency builders will be present in amounts of from 5 to 70% by weight of the final product, amounts of from 25 to 40% by weight being more general .

OTHER DETERGENT ADJUVANTS

The slurries can also contain a number of optional components such as lather controllers, anti-redeposition agents such as sodium carboxymethlycellulose, fabric softening agents such as quaternary ammonium salts either alone or in combination with clays, anti-ashing aids, starches, slurry stabiliziers such as homopolymers of acrylic acid and copolymers of acrylic acid and maleic acid; ethylene and maleic anhydride, and of vinyl methyl ether and maleic anhydride, usually in salt form; antioxidants and fluorescers.

In a final process stage the spray-dried powder produced can be dosed with ingredients that are incompatible with the spray-drying process conditions in the amounts required to produce a finished powder. Components may be incompatible for many reasons, including heat sensitivity, pH

sensitivity, degradation in aqueous systems and the like.

The usual heat-sensitive zwitterionic surfactants such as derivatives of alphiphatic quanternary ammonium phosphonium acid, sulphonium compounds in which one of the aliphatic constituents contains an anionic water solubilizing group may be added. Additional components which may be added in this manner are sodium perborate mono- and tetrahydrates, sodium percarbonates and acid bleach precursors such as

tetracetylethylene diamine, tetracetylglycouril and sodium nonyl oxybenzene sulphonate, perfumes, enzymes and composite adjuncts. -The process is especially suitable for use where it is intended to add composite adjuncts to the spray-dried powder in a dry-dosing step, since such adjuncts normally have very high bulk density and tend to separate from lighter powders. Examples of composite adjuncts are antifoam

granules, for instance, granules based on a starch core having a coating of a mixture of liquid and waxy

hydrocarbons; composite colored speckles prepared in any way, e.g., containing spray-dried base powder granulated with a colored binder solution; and adjuncts containing calcium carbonate seed crystals such as high surface area calcite (80-90 m²g^-1).

The following examples will more fully illustrate that embodiments of this invention. All parts, percentages and proportions referred to herein and in the appended claims are by weight of the total composition unless otherwise stated.

EXAMPLE I

The mixer includes a ^Lightnin(R) A-320 impeller to promote mixing. 252 lbs. of water is charged into the mixer and heated to 100-120°F. The agitator is set at 40 RPM. 121 lbs. of 50% caustic solution (enough for the neutralisation reactions of precursor alkylbenzene sulfonic acid and citric acid) is added next while maintaining the agitator at about 40 RPM. A temperature rise to 130-140°F is observed.

At this point 200 lbs. of nonionic surfactant (in this case, Neodol 25-7, a 7EO nonionic) are pumped into the mixer with the agitation still set at about 40 RPM. The temperature is observed to decrease approximately 10°F to 120-130°F. Close to the end of or after the nonionic charge the agitator may be increased to about 50 RPM, 196 lbs. of alkylbenzene sulfonic acid is then added. As the acid neutralizes the temperature increases and the mixture turns from a

transparent emulsion to a brown liquid to a white paste. As the mixture reaches the white paste stage, the slurry mixture becomes significantly thicker. It may be necessary to increase the agitation to about 60 RPM during the acid addition in order to promote good mixing and quicker

neutralisation, a short period of about three minutes after the end of the acid addition is beneficial in order to help ensure full neutralisation. The temperature increase from the neutralisation reaction is about 30-40°F resulting in a slurry temperature of 160-165°F.

After neutralisation 95 lbs. of citric acid (for example, Citrosol^(R) 503, a 50% solution) is charged into the mixer. A second neutralisation reaction takes place and the temperature rises 10-20°F to 175-185°F. Increasing the agitation to about 70 RPM and a two minute hold time is beneficial after the citric acid addition in order to

facilitate mixing and completion of the reaction. 58 lbs. of sodium sulfate, a viscosity adjuster, is added at this point. A few minutes may be necessary for complete mixing of the sodium sulfate. No effective temperature change is observed. 0.16 lbs. of Silicone defoamer is added in order to help remove entrapped air bubbles from the slurry. Removal of entrapped air results in a denser slurry which in turn will result in a denser spray-dried powder. Prior to the zeolite solids addition, the agitator should be increased to about 80 RPM. At this point 440 lbs. of 4A zeolite is charged into the mixer. The addition of room temperature solids decreases the temperature of the slurry to 155-165°F. As the solids are mixed, the slurry viscosity increases and it may be necessary to increase agitation to about 90 RPM during zeolite addition or at the end of zeolite addition prior to sodium carbonate addition. 176 lbs. of sodium carbonate are now charged into the mixer. An increase of 5-10°F to a slurry temperature of 160-170°F is observed as the sodium carbonate hydrates. The slurry appears thinner (i.e. lower viscosity) at this point. 5.1 lbs. of a fluorescent whitener is added next. No temperature increase is observed. Once the whitener is added, the agitation is increased to about 100 RPM and the slurry is heated to a final temperature of 180-185°F. A final hold time of 5 minutes may be employed to ensure complete mixing of all ingredients. A calculation of

Reynolds Number N_Re on the final slurry is as follows: fl P

N = impeller speed

D = impeller diameter

p = density (specific gravity)

μ = viscosity (at Nπ shear rate)

N = 100 RPM = 1.667 revolutions (rev)

sec

D = 23 inches = 58.42 cm

p = 1400 g/L = 1.4 kg/L

Nπ= (1.667 rev) (3.1416 1 ) = 5.2 1

sec rev sec

μ ~ 36,725 cP at 5.2 1

sec π = 3.1416

N_Re = 68

Careful temperature control is important since batches which have been heated above 200°F have been observed to separate and char the nonionic. The slurry described herein may be made, pumped and circulated through piping without physical separation issues provided appropriate temperatures are maintained.

EXAMPLE I I

A powder is prepared from the slurry of this invention containing the following ingredients:

EXAMPLE III

This slurry formulation will yield an approximate Slurry Moisture Content (SMC) of 30%. Water losses due to evaporation may result in a lower SMC measurement. Extra water can be added to compensate.

EXAMPLE IV

Slurries were prepared as in Example I but the ingredients were varied.

A. LAS/NI 1:1

Slurry Moisture Content 30%

Zeolite **

Sodium Sulfate 8%

In order of Addition

B. LAS/NI 1:1 25% total

Slurry Moisture 30%

Zeolite 4A

Sodium Sulfate 4%

In order of Addition

C. LAS/NI 1:1 35% total

Slurry Moisture 25%

Zeolite 4A

Sodium Sulfate 4%

In order of Addition

D. LAS/NI 1:1 35% total

Slurry Moisture 25%

Zeolite 4A

Sodium Sulfate 8%

In order of Addition

E. LAS/NI 1:1 40%

Slurry Moisture 20% Zeolite 4A

Sodium Sulfate 4%

In order of Addition

F. LAS/NI 1:1 25% total

Slurry Moisture Content 30% Zeolite 4A

Sodium Xyiene Sulfonate 1%

In order of Addition

G. LAS/NI 1:1 25% total

(premanufactured and neutralized blend)

Slurry Moisture Content 30%

Zeolite 4A

Sodium Sulfate 4%

In order of Addition

The compositions of Example I, II, III and IV A through F all use separate mixing of the anionic and nonionic actives.

Example IVG is a prepared neutralized blend. In Example I, II, III and IV A through F, the surfactant mixtures were prepared as taught herein. Premanufactured or prepared blends either neutralized or not could be employed in place of the individual addition. The blends may be prepared as follows:

LAS: Sodium Salt of C₁₁-C₁₅ Alkylbenzene sulfonic acid

(Stephan trademark Bio-Soft S-100) NI: Nonionic surfactant (C₁₂-C₁₅ alcohol ethoxylates),

Shell trademark Neodol 25-7

N13EO: Nonionic surfactant (C₁₂-C₁₄ alcohol ethoxylates),

Shell trademark Neodol 25-3 liquid phase gel formation

EXAMPLES V-VII

The neutralized mobile liquid surfactant mixture listed in Example V is prepared by mixing the nonionic surfactant with the indicated amount of concentrated aqueous sodium hydroxide solution (50 w/w%) and subsequently mixing with alkylbenzene sulfonic acid, Stepan Bio-Soft S-100. Examples V-VII

indicate that a higher NaOH content maintains the liquid state for a higher level of water present in the composition. The percentages reported in the following Table are based on the final total content of materials.

EXAMPLES VIII-X

The following liquid surfactant mixtures are prepared by mixing the nonionic surfactant with concentrated aqueous sodium hydroxide solution (50 w/w%) in an amount

stoichiometric to the alkylbenzene sulfonic acid plus the excess quantity of NaOH solution. This mixture is then mixed with the alkylbenzene sulfonic acid. The viscosity is measured by a Contraves Rheomat model 108E at room

temperature. Examples VIII-X demonstrate the effect of the excess of sodium hydroxide in reducing the viscosity of the surfactant compositions.

EXAMPLES XI-XV

The following mobile liquid surfactant mixtures are prepared by mixing the nonionic surfactant with concentrated aqueous sodium hydroxide solution (50% w/v) in an amount which is slightly less than stoichiometric to the alkylbenzene

sulphonic acid, adding the C₁₀-C₁₃ alkyl benzene sulphonic acid and then a small amount of a 50% (w/v) sodium hydroxide solution to bring the pH to a value of about 8. Due to the exothermic neutralization reaction, the temperature is raised to about 80°C.

Finally, the indicated amount of the fatty acid are added to the mixture.

The pH of the mixtures of Examples XII-XV was between 5.5 and 7 at a temperature of about 80°C.

It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in the light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims.

Claims

1. A process for preparing by spray-drying, washing powders comprising about 5 to 50% anionic active, about 1 to 50% nonionic active and about 5 to 70% of a builder selected from the group consisting of zeolite, sodium carbonate and

mixtures thereof, comprising preparing under agitation a anionic-nonionic active mixture containing water, a nonionic active, an anionic active and optionally a viscosity adjuster wherein the anionic active is incorporated as: i) the acid form of an anionic surfactant and the mixture further contains a neutralising agent whereby the anionic surfactant is formed in situ by neutralisation of the said acid form; and/or ii) an anionic surfactant; adding to said anionic-nonionic active mixture a builder and optionally other detergent adjuvants to form a final slurry mixture having a water content not in excess of about 35% by weight, a viscosity of about 1000 to 20000 cps measured at a shear rate of 17 to 18 sec^-1 and a temperature of 135° to 195°F and spray-drying the said final mixture.

2. A process according to claim 1 comprising:

A. preparing under agitation a mixture of water, optionally a viscosity adjuster and at least sufficient alkali metal hydroxide to result in neutralisation of the acidic form of said anionic active;

B. adding under said agitation to said mixture, sufficient nonionic active to prepare said powder, thus resulting in a nonionic active mixture; C. adding under said agitation, to said nonionic active mixture a sufficient amount of the acidic form of said anionic active to result in said powder, thus forming an anionic-nonionic active mixture;

D. then adding to said anionic-nonionic active mixture

under sufficient agitation sufficient builder and other detergent adjuvants to result in said final powder, thus forming a final slurry mixture, said final mixture having a maximum amount of about 35% water;

E. optionally adding a viscosity adjuster, in an amount of from 0 to 50% of said mixture, at any time during the slurry process to result in a viscosity of the final slurry mixture of about 1000 to 20,000 cps measured at a shear rate of 17 to 18 sec^-1 and a temperature of 150° to 195°F;

F. then adjusting, if necessary, the temperature of said final mixture to about 135°F to 195°F and spray-drying said final mixture.

3. A process according to claim 1 comprising: A. preparing under agitation a mixture of water, optionally a viscosity adjuster, optionally sufficient alkali metal hydroxide to result in neutralisation of the acidic form of desired adjuvants and a prepared surfactant blend containing anionic and nonionic surfactants thus forming an anionic-nonionic active mixture, said blend

containing about 10% to 80% anionic surfactant, 10% to 80% nonionic surfactant and 0% to 35% water;

B. maintaining the temperature of said anionic-nonionic mixture below about 200°F; C. then adding to said anionic-nonionic active mixture under sufficient agitation sufficient builder and other detergent adjuvants to result in said final powder, thus forming a final slurry mixture, said final mixture having maximum amount of about 35% water;

D. optionally adding a viscosity adjuster, in an amount of from 0 to 50% of said mixture, at any time during the slurry process to result in a viscosity of the final slurry mixture of about 1000 to 20,000 cps measured at a shear rate of 17 to 18 sec^-1 and a temperature of 150° to 195°F;

E. then adjusting, if necessary, the temperature of said final mixture to about 135°F to 195°F and spray-drying said final mixture.

4. A process according to any preceding claim wherein the temperature is controlled between about 50°F and 200°F.

5. A process according to any preceding claim having an anionic to nonionic ratio of about 1:3 to 3:1.

6. A process according to any preceding claim wherein said final slurry mixture has a water content of about 10% to about 35%.

7. A process according to any preceding claim wherein sufficient agitation is achieved with an impeller wherein said final slurry has a flow with a Reynolds number of about 1 to 10,000 in the mixer.

8. A process according to claim 2 in which steps A, B and C may be performed in any order.

9. A spray-dried product prepared by the process as defined in claims 1 to 8.

10. A slurry as defined in claim 2, step E or claims 3 step D.