US3133024A - Heat-dried detergent processes - Google Patents

Description

States Patent gfiice hatented May 12, 1964 HEAT-DRIED DETERGENT PROCESSES Harold E. Feierstein, Creve Coeur, Raymond L. Liss, Kirkwood, and Leo J. Weaver, Creve Coeur, Mo.,'

assignors to Monsanto Chemical Company,-St. Louis,

I Mo., a corporation of Delaware- No Drawing. Filed Mar. 14,1961, Ser. No. 95,487

' 11 Claims. (CI. 252- 138) I This invention relates methods for preparing heat-' dried detergent compositions containing sodium tripoly-' phosphate.

More particularly, this invention relates to improved processesfor preparing free-flowing heat-dried detergent compositions. containing hydrated sodium tripolyphosphate, which improved processes are substantially free of some of the difficulties that are inherent in conventional heat-drying processes.

conventionally, heat-dried detergents containing sodium tripolyphosphate are made by first preparing a fluid mixture of water, detergent substances (surface active dium sulfate, tetrasodium pyrophosphate, sodium carbonate, etc.), adding sodium tripolyphosphate to this mixture, allowing the sodium tripolyphosphate to hydrate and subsequently heat-drying theresulting slurry either by basically different processes for the preparation of deter-- gent slurries particularly if the detergent is to be heatdried by spraying: i.e., he can either (1)' hydrate the sodium tripolyphosphate in the slurry before it is heatdried, or he can (2) heat-dry the slurry-1 before the sodium tripolyphosphate has. been substantially hydrated;

No matter which of these processes the manufacturer utilized prior to this invention, there were certain inherent shortcomings'in the process he chose. Thus, if the manufacturer chose to dry his slurry before the sodium tripolyphosphate wasv substantially hydrated, unpredictable changes in the viscosity-of the slurry, effected by the still-hydrating sodium tripolyphosphate,often resulted in inadequate control of the rate at which the detergent slurry was dried, which, in turn often resulted in either incompletely dried or over-dried and sometimes scorched detergent product. The problem of controlling the viscosity of detergent slurries that contain actively hydrating sodium tripolyphosphate has been a particularly difficult one due to the many factors that can'effect the rate at which the tripolyphosphate hydrates (such as the crystalline form of tripolyphosphate, the moisture content of the tripolyphosphate, the type of organic detergentac- .20 agents), and usually certain inorganic salts (such as sotergent slurry only afterthe sodium tripolyphosphate v Q tive materials, but in water, the initial temperature of tive material present in the slurry,the amount of seed 1 crystals of sodium tripolyphosphate that remained in the crutcher fromthe last previous batch of slurry, etc.). Additionally, unless the sodium tripolyphosphate vhad been substantially hydrated before the detergent slurry wasdried, the resulting detergent product almost invariably became lumpy, caked readily after it was packaged, and was therefore not of a sufficiently good physical quality to sell to the consuming public. Conversely, if the detergent manufacturer did allow sufficient time to cleavage, yielding equimolar quantities of orthophosphate and pyrophosphatc, which are notas eflicient as water softeners for detergents as is the tripolyphosphate.

The present invention makes it possible for the manufacturer of heat-dried detergents to produce a detergent product having excellent over-all physical properties, which product contains almost all of the sodium tripolyphosphate that was initially formulated into the detergent slurry in an undegraded state; An additional advantage of thepresent invention is that, by its practice, one

can significantly increase the total capacity of existing slurry-crutchin'g facilities without a proportional outlay of additional capital.

Another advantage of the present invention is that, I

by its practice, the total processing cost of producing spray-dried detergent can be reduced. Other advantages and objects of'this invention will be readily apparent from the following description.

Briefly stated, the present invention, which is a=new process for the preparation of heat-dried detergents, requiresthat at least two related acts be performed. First,

sodium tripolyphosphate is'substantially hydrated in an aqueous system that contains, at most, only a relatively small amount of organic detergent active material (often called the, surfactant"), and second, the remainder of the organic detergent active material is added to the dehas been substantially hydrated.

The invention .is surprising because it was heretofore believed that in order to avoid the formation of hard,

gritty lumps of an anhydrous sodium tripolyphosphate (covered with a layer of sodium tripolyphosphate hexa- =ture of the water is sufficiently high when the sodium tripolyphosphate is added, the sodium tripolyphosphate can be mixed with the water and hydrated in the absence of at least the greater proportion of the organic surface active agent without the formation of the troublesome lumps described above.

If the sodium tripolyphosphate is hydrated in the absence of the greater portion of the organic detergent acwhich was generally above about 55 C., the troublesome, gritty lumps described above do not form. I Thus,

when one practices the tripolyphosphate hydration step according to this invention, then in order to produce the form, non-lumpy slurry. The phrases initial temperature and initial water temperature as utilized herein means the temperature of the water when the sodium tripolyphosphate is blended into it.

' some extent upon the relative amounts of the low temelapse (after the addition of the sodium tripolyphosphate peratureand high temperature crystalline modifications in the sodium tripolyphosphate which is utilized for the formulations of the detergent slurry. Usually, for exaisaazt tion or form, the initial water temperature should be below about 80 C.-if relatively complete hydration of v the sodium tripolyphosphate is desired. Otherwise, the initial water temperatures as high as 95 C. or even up to about 110 C. can be utilized so long as the temperavent the formation of the. above-described lumps.

The presence, in the water, of reasonableamounts of materials other than the organic detergent active mate- 1 rials (such as carboxymethylcellulose, silicates, sodium sulfate, sodium carbonate, 'tetrasodium pyrophosphate, etc.) when the sodium tripolyphosphate is added to the aqueous medium apparently has no detrimental efiect upon the excellent results which can accrue to those who practice this invention.

Note that the terms detergent slurry and anionic slurry as utilized in the present specification and claims are each intended to mean a separate and distinct type of slurry. By .detergent slurry. is meant the slurry that exists during the first step in the processes of this invention; that is, a slurry which contains sodium tripolyphosphate and not enough organic detergent active ingredient to materially reduce the rate of hydration of the sodium 'tripolyphosphate (as compared to the rate of hydration of the tripolyphosphate in the absence of surfactant). Generally,'the rate of hydration'of the tripolyphosphatewill not be materially reduced (i.e. by more thanabout so long as the detergent slurry does not contain more than'about 10 weight percent (based on optimum results, no more than a trace of the surfactant.-

The term anionic slurry as is herein utilized encompasses those blends of some of the anionic surface active agents contemplated by this invention with water, and

lent over-all functional and physical qualities according to this invention it is necessary that at least a major portion of the sodium tripolyphosphate contained therein be hydrated to the hexahydrate before at least the greater portion of the organic detergent active material is blended into the detergent slurry. Generally, for best results, at

least about 75%, and preferably more than about 90%,

of the sodium tripolyphosphate should be hydrated to the hcxahydrate before it is blended with the greater portionv of thesurfactant, In the present specification and claims, v I

the term substantially hydrated," which is used with ref erence to the degree of hydration of the sodium tripolyphosphate, is intended toinclude any sodiumtripolyphosphate, more than about 75% of which is in. the form of the hexahydrate.

Ordinarily one can determine approximately the percentage of sodium tripolyphosphate in a givendetergent slurry that has been-hydrated at-any given time after the addition of the sodium tripolyphosphate simply by meas uring the viscosity of the slurry and comparing the viscosity actually measured with the maximum viscosity attained by a similar detergent slurry under similar conditions. The aforesaid maximum viscosity represents the viscosity of the slurry which contains completely hydrated sodium tripolyphosphate. in agiven detergent slurry, then, is generally at least about 75% hydrated when the viscosity of the slurry containing the said sodium tripolyphosphate has increased to within about 10 percent of the maximum viscosity it will attain when completely hydrated under approximately the same conditions, while at least about 90% of the sodium tripolyphosphate in a given detergent slurry has been hydrated when the viscosity of the detergent slurry has increased to within about 5% of the maximum viscosity that the said detergent slurry will attain under approximately the sameconditions. For example, when parts of sodium tripolyphosphate are blendedinto parts of water at an initial water temperature of C.,

perhaps a diluent such as sodium sulfate, etc., which anionic slurries generally do not containsodium tripolyphosphate. A typical anionic slurry" that is commercially available today and widely used in the detergent industry contains about 54 weight percent of sodium dodecyl benzene sulfonate, about 4 weight percent of sodium sulfate, about 3 weight percent of sodium benzene sulfonate, and about 39 weight percent of water. Generally the anionic slurries" contemplated herein will contain between about 30 and about 70 weight percent of water.

Because of the relatively high temperatures employed during the tripolyphosphate hydration step of the processes of this invention, one might ordinarily expect that the rate of hydrolytic degradation of the sodium tripolyphosphate" would berelatively high (as compared with that of conventional low temperature hydration procedures). Surprisingly, however, the net result of practicing this invention is just the opposite. Apparently, the benefits (in the form of a significantly lower rate of hydrolytic degradation) which one achieves by excluding the organic surface active agents from the detergent slurry until after the tripolypho'sphate is hydrated, combined with theincreased rate of hydration of the tripolyphosphate (in the absence of the surface active agent), more than offset the potentially adverse effect of hydrating the tripolyphosphate at the relatively higher temperatures. Thus, by practicing this invention one can produce a heat-dried detergent product that contains considerably more of the sodium tripolyphosphate that was initially formulated thereinto in an undegraded state than is presently possible using conventional processes to produce spray-dried detergents containing substantially hydrated sodium tripolyphosphate.

In order to produce detergent products having excelthe apparent viscosity of the resulting slurry increases from about 150 centipoises to about 750 centipoises when of the sodium tripolyphosphate is hydrated, to about 790 centipoises when of the sodium tripolyphos- .percent, or even more, of water. -As a practical matter,

though, the sodium tripolyphosphate that is commercially available and least expensive will ordinarily be used. For example, the least expensive tripolyphosphate that is available today is anhydrou's sodium tripolyphosphate, which usually contains between about 0.01 and about 1 weight percent of water. -It is also preferred that the sodium tripolyphosphate that is utilized in the present invention be in the physical form which can be most readily dissolved in water and can be used in conventional detergent slurry processes, as for example, powder,

flake, or light or medium density (cg. up to about 0.9 gram per cubic centimeter) granular form.

equipment that is essential for the hydration step, for

example, is a container, fitted with means for heating and cooling its contents, and a fairly efilcient mixer.

The term organic detergent active material is intended herein to encompass water-soluble organic surface active agents which are compatible with sodium tripoly- The sodium tripolyphosphate ataaoaa phosphate. It is intended to include both the water-soluble anionic and the water-soluble nonionic classes of sur face active agents.

The water-soluble anionic-class of surface'active agents includes such well-known materials as the higher alkyl (i.e. C to C aryl sulfonic acids, and their alkali metal and alkaline earth metal salts (such as, for example, so-

dium dodecylbenzene sulfonate, sodium tridecylbenzene sulfonate, magnesium dodecylbenzene sulfonate, 'potasagents includes thoseproduced by condensing one or more alkylene oxides, .such as ethylene oxide or propylene oxide, with a relatively hydrophobic compound such as a fatty alcohol, fatty acid, glycerol, a fatty glyceride, a

fatty amine, an arylamine, a fatty mercaptan, tall oil, etc.; and also includes those produced by condensing one or more relatively lower alkyl alcohol amines (such as ethanolamine, methanolamine, propanolamine, etc.), with a fatty acid such as lauric acid, cetyl acid, tall oil fatty acid, abietic acid, etc., to produce thecorresponding amide; as' well as any other water-soluble nonionic surface active agents that can be melted below about 300 C.

The actual 'physical manipulation of the materials (from which the final spray-dried detergent product is made) through the various stages or steps of the processes contemplated by this'invention will depend to .a consider- (commonly termed surfactant) which is to be utilized.

minimum amount of water can be utilized. However, as a practical matter, detergent slurries having more than about 45 weight percent of water are seldom heat-dried commercially. because of the increase in production cost which results from the evaporation of the excess water during the heat-drying step. a

Because the above-described: minimum amount of water must be maintained through'the hydration (of tripolyphosphate) step of the'processes contemplated by this invention, .and because the anionic slurries described heretofore will ordinarily not bev combined with the remainder of the detergent slurry until sometime after the major portion of the sodium tripolyphosphate has been hydrated it can be seen that with certain formulations under certain conditions, limitations upon the total amount of sodium trtipolyphosphate and/or the amount of anionic slurry which can be utilized in a given formulation will exist. For example, because of the minimum ratio of free water to tripolyphosphate which must ordinarily be maintained in the detergent slurry, one could not spraydry a formulation such as that shown in Table I at a final detergent slurry solids" (material that is not evaporated at 110? C.) concentration of 60 weight percent if the anionic slurry utilized therein contained no more than about 60 weight percent of solidsjunless the sodium tripolyphosphate content of the formula were reduced to less than about parts.

For example, if the surface active agent is utilized in the I I form of a water-containing slurry, special consideration must be given to the amount of water contained in this surfactant slurry. But if the surfacant is utilized in the liquid form, or as a solid, certain other precautions should be observed if thejdetergent manufacturer wishes to produce' the highest quality detergent product possible from his raw materials at reasonably low costs. It is because of these varying manipulative requirements with respect to the physical form of the surfactants that are utilized in the processes of the present invention that the following detailed discussion is subdivided into the groups: anionic-slurry, anionicsolid, anionic-liquid, nonionicsolid, nonionic-liquid.

ANIONIC-SLURRY By far the greater majority of spray-dried detergents today contain as their major organic detergent active material, a-sodium higher. alkylaryl sulfonate. Almost invariably, this sodium higher alkylaryl sulfonate is formulated into-the detergent composition (in the crutcher) as a water-containing slurry. Such sulfonate slurries usually comprise between about 30 and about 65 weight ably low viscosity so'that it can'be pumped if desired from the crutcherto the drying facility, a certain amount of water in excess of that actually required to'hydrate the sodium tripolyphosphate must be present in the detergent slurry throughout the entire crutching operation. Ordinarily this excess of water amounts to at least about one and one-half times, and preferably at least about two and one-half times, the weight of-sodium tripolyphosphate in the detergent formulation. Of course, more than this Material Sodium tripolyphosphate 50 Tetrasodium pyrophosphate 15 Sodium sulfate 20 Sodium carbonate 10 Sodium silicate (solids basis) 10 Sodium tridecylbenzene sulfonate 20 If, in the above example, the anionic slurry contains relatively fewer solids than 60% (i.e. more water), then still lower levels of the tripolyphosphate'will have to be resorted to in order to maintain the desired 60% final detergent slurry solids concentration (immediately prior to the heat-drying step of the processes encompassed by 7 this invention).

While it can be seen from the foregoing that in some instances when anionic slurries are utilized in the practice of this invention, special consideration must .be given to the relative proportions of sodium tripolyphosphate, water, and surface active agent in the formulation, the considerations and calculations which must sometimes be made are nevertheless well within the abilities of anyone normally skilled in the art, and therefore should present no serious obstacle to anyone wishing to practice this invention. I

Because of their physical form, the anionic slurries will ordinarily be pumped from storage to wherever they are utilized in the over-all detergent processes. Therefore, it is a relatively simple task to combine the anionic slurry with the detergent slurry (which contains the hydrated sodium tripolyphosphate) in any conventional manner that will yield a fairly uniformblend of the surface active agent with the other detergent ingredients before it is actually heat-dried. An extremely uniform blend of the two slurries will result, for example, if they are combined on the inlet or exit side of the pump which, subsequently, moves the'resulting final detergent. blend to the spray nozzles. The anionic slurry can also be blended into the other detergent ingredients in the crutcher itself, after the sodium tripolyphosphate has been sufficiently hydrat'ed.

One of the valuable results which can accrue to one who practices this inventiton, however, is that, when the anionic slurry is blended with the detergent slurry at some point after the detergent slurry is removed from the crutcher (for example, when it is being transported to Parts by weight the drying facility), there will be an appreciable-increase I Ingredient:

in the total capacity of the detergent plant (compared with thatwhich resulted from the utilization of conventional processes in this same plant). Actually, if one practices this invention in one of the preferred manners, i.e. by blending the anionic slurry with thedetergent slurry at some point after the detergent slurry has been removed from the crutcher, the minimum increase in total detergent plant capacity that one can achieve (as compared to the total plant capacity when conventional procedures are utilized), should be at least equal to the volumepercent of anionic slurry that the detergent manufacturer includes in his formulation. For. example, in a process in which prior to this invention, the anionic slurry represented about 30 volume percent of the materials charged into the detergent crutcher, the expedients by which this invention is practiced make it possible to increase the total capacity of this same plant by at least about 40%, or even more (30% by adding the anionic slurry after the other ingredients are removed from the crutcher, and

an additional or more due to the increased rate of hydration of the sodium tripolyphosphate in the crutching step).

One of the procedures for the utilization of anionic.

slurries according to this invention is illustrated in Example I.

EXAMPLE 1 Into a detergent crutcher are charged the following ingredients (which, in this case, fill the crutcher to approximately its volume capacity).

'The resulting blend is heated to 70 C., after which 3000 pounds of sodium tripolyphosphate (containing 60 weight percent of the low temperature crystalline form and 0.4 weight percent of water) is added over a six minute period of time. .While being stirred for an additional 12 minutes, the temperature of the resulting detergent slurry rises to about 80 C. while its apparent viscosity (measured by the Bendix ultra-visicon) increases to approximately 800 units (from about 200 units before the sodium tripolyphosphate is added). The maximum viscosity that a detergent slurry of this formulation will attain under these'conditions is about 865 units. Therefore, it can be seen that approximately 90% of the sodium tripolyphosphate in this detergent slurry is hydrated in about 12 minutes after the sodium tripolyphosphate is added to the crutcher.

As quickly as possible after the detergent. slurry hasreached an apparent viscosity of about 800 units, it is pumped from the crutcher through'a flow-meter to a high pressure pump. Into-this detergent slurry on the inlet side of the said high-pressure pump is injected an amount of an anionic slurry (composed of 52 weight percent of the sodium salt of dodecylbenzene sulfonic acid, 3 weight percent of sodium benzene sulfonate, 0.5 weight percent of sodium sulfate and 54.5 weight percent water) equal to 40 weight percent of the amount of the above-described detergent slurry (containing the substantially hydrated tripolyphosphate) which is being pumped intothe said highpressure pump. From the high-pressure pump, the resulting blend is transported to a conventional spraying facility, where it is spray-dried to yield a detergent product containing the following ingredients (anhydrous basis) in approximately the following amounts.

Pounds 8v 7 l 7 Weight percent Sodium dodecylbenzene sulfonate 22.4 Sodium curnene sulfonate 1.3 Sodium sulfate 27.0 Sodium carbonate 'Y 4.5 1 Sodium silicate -e 4.5 Tetra'sodium pyrophosphate 13.4

' Sodium tripolyphosphate. 27.0 1 Sodium carboxymethylcellulose 1.0 Optical bleach 0.1 v

The total capacity of the plant that utilizes the abovedescribed process, is thus, increased by at least 40 percent,

as compared to the total capacity of the same plant that utilizes the conventional technique of hydrating the sodium tripolyphosphate in a crutcher which contains, in addition to the other detergent ingredients, the anionic slurry. When-one also considers the effective increase in the rate at which the sodium tripolyphosphate hydrates when one practices the instant invention, it can be seen that the total capacity of the plant is increased still further. For example, in Example I, 90% of the sodium tripolyphos' phate is hydrated in about 12 minutes after the tripolyphosphate is added to the crutcher. If the anionic slurry had been presentin the crutcher before the tripolyphosphate was added, the sodium tripolyphosphate would have required at least about 30 minutes to hydrate to the same degree as that in Example I.

In order to demonstrate the benefits of the processes of this invention insofar as decreasing the degradation of the sodium tripolyphosphate (by way of hydrolysis, or

hydrolytic degradation) is concerned, one gram samples of detergent products, which have been sprayedried as soon as 90% of their sodium tripolyphosphate has been hydrated, are dissolved in 100 mls. of water. Then the pH of the resulting solutions is measured. Since the product's from the degradation of sodium tripolyphosphate are acidic the sample with the. higher pH contains proportionately more undegraded tripolyphosphate than does the other sample. to this invention contains more undegraded sodium tripolyphosphate than that which is prepared via the conventional process of hydrating the tripolyphosphate in the presence of the surface active agent; Table 2 lists data from such a comparision.

Table 2.-Acidity of Heat-Dried Detergents 1 Time for viscosity to reach 95% of peak viscosity [or slurry.

ANlONlC-SOLID Although the solid forms of the anionic surface active agents such as sodium pcntadecylbenzene sulfonate, mag-' nesium dodecylbenzene sulfonate, sodium octadecyl sulfate, sodium tetradecyl thiosulfate, and the like (often containing solid diluents such as urea, sodium sulfate, etc., blended therewith), are not so widely used conventionally in the preparation of spray-dried detergents as are the anionic slurries, they are used to some extent, and can also be used in the practice of this invention. Actually,

.the use of the solid anionic surface active agents according to this invention are advantageous in some respects over the use of the anionic slurries described heretofore,

because their (solid anionics) use makes it possible to 0 charge all of the water which is to beutilized in the .formulation into the crutcher either prior to or during the hydration of the sodium tripolyphosphate, thus contributing' to a substantial decrease in the viscosity of the Note that the samplepreparedaccording arsaoes .hydrated for about 8-l0 minutes, the detergent slurry is metered from the crutcher into a 30.gallon mixing vessel containing a l horsepower high-speed dual-propeller-type mixer. The solid anionic surfactant (85 sodium dodecylbenzene sulfonate+% sodium sulfate, in one instance) is also metered intothe same mixing vessel, at a rate-which results .in the-formation of a final slurry containing the proper ratio of anionic surface active agent.

to sodium tripolyphosphate that is desired in the final product. The average sojourn time in the said mixing vessel for the resulting slurry will vary, depending upon many factors which arewell within the skill of those in the art to consider and control. Usually, however, the blending of the solid anionic surfactant and the deterbe already present along with the hot water in the crutcher when the sodium tripolyphosphate is added thereto, since, thereby, the rate of hydration of the sodium tripolyphosphate is desirably increased. 7

While it is particularly desirable, when practicing this invention and utilizing the liquid anionic surfactants, thatfthe alkaline ingredients heretofore described be well mixed with the water-soluble anionic acids before the final'slurry blend is heat-dried, it is not essential that the said alkaline ingredients be presentin the detergent slurry before the anionic surfactant acid is added. For example, it is possible to add the said alkaline ingredients to an already-prepared blend of thedetergent slurry with the anionic surfactant acid a short time before the resulting slurry is'heat-dried, and produce adetergent having all of the improved properties described heretofore.

Since, by their nature, the'water-soluble anionic acids contemplated herein are liquids, they will ordinarily be pumped from storage to wherever they are to be utilized in the over-all'detergen't processes. These acids, just as their anionic slurry counterparts, can be combined with gent slurry should be done as quickly as possible, since, in

ANIIONIC-LIQUID,

The water-soluble anionic surface active agents which. are contemplated under this heading are those that do not the detergent slurry in 'any conventional manner that will yield a reasonably'uniform blend of the surface active agent with the other detergent ingredients before they are.

EXAMPLE n Into'a detergent crutcher are charged the following ingredients (which ingredients together represent approxicontain substantially more than perhaps a trace of water; I

i.e., those, the natural physical form of which is liquid. Actually, the liquid anionic surface active agents which fall into this classification are almost solely the anionic surfactant acids, such as alkyl sulfonic acids, alkylaryl sulfonic acids, alkyl sulfuric acid esters etc. These acids are generally easy to handle and pump (especi'ally when i they are warm), are relatively inexpensive, are generally acids often degrades when they are held for extended times at extremely high temperatures without being neutralized, it is preferred that the temperature of these acids be maintained below about 200 C. and even more preferably, below about 75 C. at all times.

So far as the actual procedural requirements that must be met when the anionic surfactant acids are utilized according to this invention, the most important one is that at some stage in the processes prior to the formulations actually being heat-dried, at least enough alkaline ingredients. (usually one or more alkali metalor alkaline earth metal-hydroxide or carbonate such as NaOH, KOH, LiOH, Na CO Mg(OI-l) Ca('OH) MgC0 etc), must be'blended into the detergent slurry to neutralize the said anionic surfactant acids. For example, the said alkaline ingredients can be charged into the crutcher at anytime prior to the discharge of the hydrated tripolyphosphate therefrom. Or the said alkaline ingredients can be injected into the system which is used to transport the detergent slurry to the spraying facility at any point along the way. If, for example, the detergent slurry and the anionic active are blended together in a separate mixing tank such as that described under the heading of Anionic Solid, above, the said alkaline ingredients can also be The fact that many of the mately the volume capacity of the crutcher).

Ingredients:

-Water 6344 Sodium silicate solution (containing 60% water) 1429 Sodium sulfate 4949 Sodium hydroxide (containing water)- I 278 Sodium.carboxymethylcellulose 100 Optical bleach e.. 9.6

-The resulting blend is heated to 65 C., after which 2900 pounds of sodium tripolyphosphate (containing 75 weight percent of the low temperature crystalline form and 0.2 weight percent of water) is added over a six minute period of time. While being stirred for an additional 10 minutes, the temperature of the resulting detergent slurry rises to about 78 C. while its apparent viscosity increases to about 920 units (from about 150 units be- V fore the sodium tripolyphosphate is added). The maximum viscosity that a detergent slurry of this type will attain is about 980 units. Therefore, it can be seen that approximately 85% of the sodium tripolyphosphate in this detergent slurry is hydrated in about 10 minutes after the sodium tripolyphosphate is added to the crutcher.

The resulting detergent slurry is then pumpedfrom the crutcher through a flow-meter to a high pressure pump. Into the detergent slurry on the exit side of the flow-meter is injected an amount of dodecylbenzene sulfonic acid (which has been previouslywarmed to a temperature :of 60 0.) equal to 10.56 weight percent of the amount of the aforesaid detergent slurry which is being pumped to blended into the other slurry ingredients at the same time.

the high-pressure pump. From the pump, the resulting blend is transported through a conventional deaerator (to remove dissolved and entrapped air) to a conventional spraying facility, where it is spray-dried to yield a freeflowing, high quality detergent product which contains almost all of the sodium tripolyphosphate that was initially added to the detergent crutcher in an undegraded state.

Another advantage of the present invention can be seen by a. consideration of the data in Table 3, in which is tabulated the power consumed in the above-described crutching operation compared with the power consumed Pounds 1 when conventional detergent crutching processes (with a similar detergent formulation) are utilized:

Table 3 Time to Power Process Hydrate, Required,

minutes nmperes As in Example m-.. 1o 17 Conventional. T 35 23 1 Time required for slurry viscosity to reach 93% of maxim The resulting detergent slurry is then pumped from the crutcher through a flow-meter, and into a SO-gallon conventional mixing tank containing a conventional impellertype stirrer. Into the same mixing tank at a rate pro- 5 portional to 7.58 weight percent of the said detergent um 1 Amount ct current drawn to stir crutcher charge during hydration.

Figure given is average for period 0! hydration shown.

1 Note that'in Example II, above, even excluding from consideration the substantialbeneficial effect of the increased.

. rate of sodium'tripolyphosphate, the process of this invention makes it possible to increase the plant capacity by at least 11 percent. i

- Similarly excellent results would result if the detergent slurry in Example. II, above, had been blended with the sulfonic acid in a separate blending tank. For example,

by continuously metering the above-described detergent slurry (which contains sulficient alkaline ingredientsto' neutralize the sulfonic acid) into a separate 50 gallondetergent product of similarly excellent qualities as that produced according to Example II. can be made.

NONIONIC SOLID The physical form of relatively-pure water-soluble nonionic surface active agents is usually either liquid or semisolid (waxy), and only rarely .solid. However, certain of the reaction products or condensation-products of some of'the nonionic surface active agents (notably the urea adducts of the nonionic surfactants that contain multiple alkylene oxide chains, for example) are distinctly solid in character and can be utilized in the practice of this invention much as can be the solid watersoluble anionic surfactants described herein-before.

EXAMPLE III Into a detergent crutcher are charged the following ingredients.

Ingredients: Pounds Water 5262 Sodium silicate solution (containing 56% water) 2147. Sodium carbonate 504 Sodium sulfate 1313 Tetrapotassium pyrophosphat 900 Sodium carboxymethylcellulose 100 Optical bleach 9.6

The resulting blend is warmed to 90 C., after which 4548 pounds of sodium tripolyphosphate (containing 93 weight percent of the high temperature crystalline form and 0.3 weight percent of water) is added over a 5 minu-te period of time. While being stirred for an additional 8 minutes, the current drawn by the crutcher stirring motor increases to 17.5 amperes (from 12 amperes initially), which current of 17.5 amperes is about 95% of the maximum current drawn by a similar slurry when the sodium tripolyphosphate contained therein is completely hydrated, and thusQsignifies that at least about 90 percent of said sodium tripolyphosphate has been hydrated (current drawn by the crutcher stirring motor during this operation is proportional to the viscosity of the detergent slurry being mixed in the crutcher).

slurry is metered a nonionic surface active agent in the solid state (composed of (a) 55* weight percent of a condensate of one mole of tridecyl alcohol with '12 moles of ethylene oxide and (b) -45 weight percent of urea). The rates at which the detergent slurry and the nonionic surfactant are poured into the mixing tank are controlled so that the resulting blend remains in the mixing tank for approximately 4 minutes (to dissolve the solid nonionic ingredient), after which the blend is transported to a conventional sprayinglfacility, where it is spray-dried to yield an excellent detergent product containing approx- 'im'ately the following ingredients.

Ingredient: .Weight percent Water 5.0 Sodium silicate 10.0 Sodium carbonate 5.0 Sodiumsulfate 13.0 Tetrapotassium pyrophosphate 8.9

. Sodium tripolyphosphate 45.0

- Sodium carboxymethylcellulose .l.0 Optical bleach 0.1 Nonionic' surfactant 12.0

Itis usually more desirable, however, to melt the nonionic surface active agents contemplated by this invention if they are not already in the liquid state, and treat them according to the procedures described under the heading of Nonionic-Liquid, below. q

NONIONIC-LIQUID Even though most of the nonionic surface active agents contemplated by this invention are either semi-solid or wax-like in physical form at room temperature, they can be readily melted and thereafter transferred from one location to another in any particular detergent plant by means of pumps and pipes. Generally, the nonionic surface active agents are less subject to a degradation of their color when they are heated than are the abovedescribed anionic acids. However, it is generally preferred that the temperature of liquid nonionics bemaintained at below about 200 C. if they are to be held at elevated temperatures for any extended period of time. Actually, a temperature of about 150 C. is sufficient to reduce the viscosity of almost all of the nonionic surface active agents contemplated by this invention to the point at which they are pu'mpable, and thus can be handled by conventional transferring, spraying and mixing equip ment. 1 The liquid nonionic surfactants contemplated herein can be blended into the detergent slurry at any point in the detergent processes subsequent to the hydration of the sodium tripolyphosphate (described above), and in any manner which is convenient. .For example, the liquid nonionic surfactants can be blended with the detergent slurry in practically the same manner as can the anionic slurries, described hereinbefore, either with or without additional water (to maintain the nonionic surface active agents in the liquid state).

7 EXAMPLE IV Into a detergent crutcher are charged the following in- The resulting blend is warmed to 70 C., after which 2217 pounds (containing 60 weight-percent of the low a temperature modification) of sodium tripolyphosphate is completely hydrated), indicating that within minutes at least about 90% of the sodium tripolyphosphate has been hydrated. The resulting slurry (containing the substantially hydrated tripolyphosphate) is then pumped to the intake side of a high pressure pump, where it is blended with a warm (40 C.) blend of nonionic surface active agents in the liquid state at a rate proportional to 14 parts of the said blend of nonionic surface active agents per .20 parts of sodium tripolyphosphate' (dry basis) in the detergent slurry.

The blend of nonionlc surface active'agents is composed of 50 weight percent each of a condensation product of one moleof nonylphenol with about 15 moles of ethylene oxide and a condensation product of 3 moles of propylene glycol with about 35 moles of ethylene oxide.

The rates at which the detergent slurry and the nonionic surfactant blend are transferred to the inlet side of the aforesaid high pressure pump are controlled so that all effected at a temperature between about 65 C.-and about 3. A 'process according to claim 1 wherein the initial temperatureof said aqueous medium isat least about 55 C., said hydration of said sodium tr-ipolyphosphate is effected at a temperature between about 55 C. and about 80 C., and at least about weight percent ofsaid sodium tripolyphosphate is the low'temperature crystalline form.

4. A process for the preparation of aheat-dried detergent composition containing a water-soluble synthetic anionic surface active agent, which process comprises the steps of first intermixing sodium tripolyphosphate with a liquid aqueous medium containing .an amount of water of the various ingredients in the resulting-final slurry will have beenthoroughly intermixed before they are heat-dried. The final slurry is pumped fromthe high pressure pump to a conventional spraying facility, where Typical Formulation of Nonionic Heat-Dried Detergent equal to at least about 1 /2 times the weight of said sodium tripolyphosphate, maintaining said aqueous medium free of an amount of said synthetic anionic surface active agent sufficient to materially reduce the rate' of hydration of said sodu-im tripolyphosphate; said amount of said synthetic organic detergent active material constituting at most about 10 weight percent of theresul ting mixture; and maintaining the aqueous 'medium at a temperature between about 55 C. and about '1 10 C. until at least about 75v weight percent of said sodium tripolyphosphate istransformed to the hexahydrate, whereby said hydration is etfected at a, rapid rate and with low degradation of said 7 sodium tripolyphosphate withoutthe formation of lumps,

and thereafter intermixing withthe resulting detergent slurry said water-soluble anionic surface active agent and then heat-drying said slurry.

5. A process for the preparation of a heat-dried detergent com-position containing a water-soluble synthetic anionic surface active agent and sodium tripolyphosphate, which process comprises the'steps of first intermixing at an initial temperature between about 55 C. and about 80 C. said sodium tripolyphosphate; said tripolyphospiate initiallyv containing at least about 20 weight percent of the low temperature. crystallinemodification; wi-tha liquid aqueous medium containing an amount of water r'norethan sufiicient to convert said sodium tripolyphoss phate to the hexahydrate, maintaining the temperature of said aqueous medium between about 55 C. and about 80 C., and also maintaining less about 5 weight percent, based on the weight of said sodium t-ripolyphos- Ingredients: Percent Water 5.0 Sodium silicate 3.0 Sodium carboxymethylcellulose 1.0 Sodium carbonate 16.9 Sodium tripolyphosphate 20.0 Tetrasodium'pyrophosphate 20.0 Alkylphenol+15 Eto 7.0 Propylene glycol-Eto condensate 7.0 Optical bleach 0.1 Sodium sulfate 20.0

What is claimed is: 1. In a process for producing a heat-dried built detergent wherein sodium tripolyphosphate is intermixed with a liquid aqueous medium containing an amount of water C. to prevent the formation of lumps that otherwise would.

be formed by the hydrating sodium tripolyphosphate in the substantial absence of organic detergent active matenial, but not at so high a temperature as to prevent the hydration of said sodium tripolyphosphate, and thereafter intermixing with the resulting detergent slurry an organic detergent active material, and then heat-dryin said slurry. 1

2. A process according to claim 1 wherein the initial temperature of said aqueous medium is at least about 65 C. and said hydration of said sodium tripolyphosphate is said aqueous medium until at least about 75% of said sodium tripolyphosphate is transformed to .the hexahydrate; and thereafter intermixing with the resulting detergent slurry said water-soluble anionic surface active agent and then heat-drying said slurry. I

6. A process for the preparation of a heat-dried detergent composition that contains a water-soluble higher alkylbenzene sulfonate, which process comprises the steps of first intermixing sodium tripolyphosphate, which contains between about 0 and about 10 weight percent of moisture, with a liquid aqueous medium which contains an amount of water equal to at least about 2 /2 times the weight of said-sodium tripolyphosphatc at an initial temperature between about 65 C. and 110 C.; said liquid aqueous medium also containing an alkali metal hydroxide selected fromthe group consisting of sodium hydroxide, potassium hydroxide, and lithiumhydroxide; maintaining the temperature of saidaqueous medium between about 65 C. and about 110 C. and maintaining said aqueous medium substantially free of any organic detergent active material until at least'about of said sodium tripolyphosphate is transformed to the hexahydrate; and thereafter intermixing with the resulting deter- I gent slurry a quantity of water-soluble higher alkylbenzene sulfonic acid and then heat-drying said slurry. 7. In a process for the preparation of a heat-dried detergent composition containing a'water-soluble synthetic nonionic surface active agent in which process sodium tripolyphosphate is intermixed with a liquid aqueous medium containing an amount of water more than '15 suflicient to hydrate said sodium tripolyphosphate to the hexahydrate, the improvement which comprises maintaining the temperature of said aqueous medium at a temperature between about 55 C. and about 110 C., and maintaining the level of said synthetic nonionic surface active agent in said aqueous medium below about 5 weight percent until at least about 75% of said sodium tripolyphosphate is utransformed to the hema'hydrate, and thereafter intermix'mgwith theresulting detergent slurry said water-soluble nonion-ic surface active agent and then beat- Y- s said. l v v 8. A processasi'n claim 5,' wherein said water-soluble anionic surface active agent is sodium dodecylbenzene 4 sulfonate. Y

9. Aprocess as in claim 5, wherein said water-s0lub1e 15 16 anionic surface active agent is sodium tridecylbenzene sulfonaite. I f

1'0. A process as in elaim 6, wherein said water-soluble higher alkylbenzenesulfonic acid is dodecylbenzene sulfonic acid.

11. A process as in claim 7, wherein said water-soluble nonionic surface active egentis .a Condensation product of nonylphenol with ethylene oxide.

References Cited in the file of this patent UNITEDSTATES PATENTS 2,622,068. Hizer Dec. 16, 1952 2,712,529 Mills et aL. July 5, 1955 2,947,701 Ruff Aug. 2, 1960 2,961,410 Martin Nov. 22, 1960

Claims (1)

1. IN A PROCESS FOR PRODUCING A HEAT-DRIED BUILT DETERGENT WHEREIN SODIUM TRIPOLYPHOSPHATE IS INTERMIXED WITH A LIQUID AQUEOUS MEDIUM CONTAINING AN AMOUNT OF WATER MORE THAN SUFFICIENT TO HYDRATE SAID SODIUM TRIPOLYPHOSPHATE TO THE HEXAHYDRATE, THE IMPROVEMENT WHICH COMPRISES MAINTAINING SAID AQUEOUS MEDIUM FREE OF AN AMOUNT OF ORGANIC DETERGENT ACTIVE MATERIAL SUFFICIENT TO MATERIALLY REDUCE THE RATE OF HYDRATION OF SAID SODIUM TRIPOLYPHOSPHATE UNTIL AT LEAST A MAJOR PORTION OF SAID SODIUM TRIPOLYPHOSPHATE IS TRANSFORMED TO THE HEXAHYDRATE; SAID AMOUNT OF ORGANIC DETERGENT ACTIVE MATERIAL CONSTITUTING AT MOST ABOUT 10 WEIGHT PERCENT OF THE RESULTING MIXTURE; MAINTAINING THE TEMPERATURE OF SAID AQUEOUS MEDIUM DURING SAID HYDRATION BETWEEN ABOUT 55*C. AND ABOUT 110* C. TO PREVENT THE FORMATION OF LUMPS THAT OTHERWISE WOULD BE FORMED BY THE HYDRATING SODIUM TRIPOLYPHOSPHATE IN THE SUBSTANTIAL ABSENCE OF ORGANIC DETERGENT ACTIVE MATERIAL, BUT NOT AT SO HIGH A TEMPERATURE AS TO PREVENT THE HYDRATION OF SAID SODIUM TRIPOLYPHOSPHATE, AND THEREAFTER INTERMIXING WITH THE RESULTING DETERGENT SLURRY AN ORGANIC DETERGENT ACTIVE MATERIAL, AND THEN HEAT-DRYING SAID SLURRY.