US2941947A - Process for the preparation of freeflowing detergent compositions - Google Patents

Description

Un d S s Patent PROCESS FOR THE PREPARATION OF FREE- FLOWING DETERGENT COMPOSITIONS Paul J. Schauer, Danvers, Mass., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed June 6, 1955, Ser. No. 513,580

9 Claims. (Cl. 252-135) This invention relates to the preparation of free-flowing, spray-dried detergent compositions. More specifically the process of this invention relates to the direct preparation of free-flowing, spray-dried detergent compositions containing a non-ionic active constituent and a plurality of alkaline builder components from the group comprising tetrasodium pyrophosphate, sodium tripolyphosphate, sodium carbonate, sodium bicarbonate, the sodium silicates, and the like, by subjecting the spray-dried material to a fluidized aeration procedure for a period of from about 10 to about 40 minutes, substantially immediately after discharge from the drier.

The prior art practice in the preparation of the subject.

class of detergent compositions required that the spraydried product be aged for at least 4 hours and preferably overnight prior to further treatment and ultimate packaging. If this were not done the product would become badly caked in the package and blocked to the extent that the consumer would have difliculty in removing the proper amount of detergent from the package. Furthermore the unaged material causes problems in the packaging operation and requires frequent Shllt-rdOWHS to clean and free the packaging machinery. As aforesaid, this difficulty was overcome by aging the product in small containers having a capacity of about 37 cubic feet and holding up to about 600 pounds of product. At the end of the aging period it was necessary to break up the caked product and pass through a series of screens to classify the material. The proper-sized product was then sent to the packaging department, and the overs were returned to the slurry preparation section of the process. The necessary recycle of overs is obviously inefiicient as it is wasteful of spray tion to produce a given amount of product. In addition the cost and maintenance of the aging vessels, the large area needed to store same, the excessive manual handling of the product, and the crushing and classifying operations all add extra costs to the product.

In the prior art formulation of the subject detergent compositions as bulk-mixed or spray-dried products it has beenadisadvantage to use the disclosed phosphates and carbonates, particularly in the presence of silicates and the active constituent, in that the hydration or aging step required considerable time to proceed to a sufiiciently advanced stage such that the material could be safely packaged.' If the composition were ground, milled or packaged before the hydration reaction was substantially complete," it was found that the material would cake or display a sticky condition'which'rendered the product difficult to package with modern automatic machinery and the packaged product had poor shelf-life, becoming caked and blocked, thereby making ultimate use diflEicult. Whereas it is not believed that the instant fluidization process actually accelerates the aging of the detergent composition, it provides a means by which the product can besafely packaged and hydration allowed to proceed" thereafter in the package without danger of agglomeratiom- P ce subject spray-dried detergent compositions by means of retaining the product in a fluidized bed for an average minimum time of about 10 minutes up to about 40 min-, utes or more under the conditions hereinafter stated. As a result, the tendency of the detergent composition to form hard lumps or agglomerates during storage is substantially eliminated. Thus the subject process provides a simple means to obtain a uniform, free-flowing product, which is readily handled in the plant packaging operation and ultimately is easily dispensed when used in industry or the home.

Fluidized beds, in general, are now well known in th chemical industry wherein they are employed to provide improved efficiency in reactions entailing gas and solid phases. The preferred apparatus to effect the desired fluidization of the detergent composition is very simple, essentially comprising a vertical cylindrical tower with a conical bottom-section afixed thereto, said conical section having a perforated plate aflixed therein at about three-quarters the distance from the inverted cone tip to the cone joint with the cylinder, which perforated plate breaks up and distributes the air relatively evenly throughout the cross-sectional area of the tower. The product is fed into the top of the tower, and, after processing, is'

removed through a discharge outlet, having a suitable valve means, located just above the aforesaid perforated plate. Air is supplied to the tower through an inlet at the tip of the cone by a multistage blower or other suitable means. A fiared section may be affixed to the top of the tower section to preclude boiling out any product from the open tower in the event of slugging during the aeration process. Whereas substantially no dust is involved in the preferred process and the tower can be safely exhausted directly into the building housing same, the tower exit gas may also be vented outside the building if desired. Formulations which may provide a minimumamount of dust in the exhaust gas stream can be cleaned up in the conventional manner by the addition of a cy-- clone separator, filter-bag dust collector, or other suitable means prior to exhausting the gas to the atmosphere.

The spray-dried product can be introduced into the top of the fluidizing tower by any suitable means, as by bucketelevator, pneumatic conveyor, and the like.

Whereas the aforesaid apparatus has been found to give satisfactory results when operated batchwise or cone, tinuously, where the product sojourn time is from about 10 minutes to about 30 minutes, other equivalent apparatus can be employed. Thus various modifications of fluidizing towers known in the prior art can be employed,

as for example, the apparatus disclosed in U.S. Patent No..-

2,690,962. Also apparatus designed to provide a plural-- ity of superimposed fluidized beds, e.g. as shown in U.S. Patents No. 2,621,118 and 2,697,653, can be employed in the instant process. The multi-stage fluidized-bed ar-- rangement does substantially reduce the possible shortcircuiting of a portion of the material through the fluidized bed. However, it has been found that by operating the above-described single-stage apparatus as a quiescent fluidized bed that the product has satisfactory storage characteristics and therefore the small portion of theproduct which may be discharged from the apparatus in less than the desired minimum average sojourn time'doesnot adversely affect the product.

It was found that tower air velocities varying from 1 about 0.5 to about 1 foot per second and preferably from as the fluidizing medium, air is preferred. The tempera:

Patented June 21, 195.0,.

ture of the fluidizing gas can vary from about room temperature, i.e. C., or lower, up to about 60 C., and normally is in the neighborhood of about 40 C. Similarly the relative humidity of the fluidizing gas can range from about 30 percent up to about 80 percent with substantially equivalent results, but the preferred condition is at about 60 percent.

The precise combination of physical and chemical effects responsible for the observed desirable result is not known. It is acknowledged that the prior art discloses the use of air as a cooling means for hot spray-dried soap and synthetic detergent products. However these operations only required a contact time of the product to the air stream for a matter of seconds. Also streams have been used .with many materials to remove the dust fractions.

The mechanism is clearly not one of merely cooling the product since, as can be seen from the example, the spray-dried product enters the tower at a temperature of about 50 C., whereas the fluidizing gas can actually enter the tower at a higher temperature. In normal practice the fiuidizing gas temperature is about 40 C., which will eifect a drop in temperature of the product, but a gas temperature lower than the product temperature is not critical of the subject process. Also the mechanism is not a supplemental drying process since it has been shown that a range of fiuidizing gas relative humidity of from about 30 percent to about 80 percent can be employed without effecting any major change in the moisture content of the product. It was found that when the relative humidity of the gas was 30, 60, and 80 percent that the moisture content of the product was slightly less,

about constant, and slightly increased, respectively, but

the changes were insignificant in amount.

The most logical theory relates to the possible preferential hydration of the various components of the detergent composition. Thus the process appears to effect surface hydration of the individual particles, while they are freely suspended out of prolonged contact with other particles, and subsequent internal hydration can continue after the product is removed from the fluidized zone without danger of fusing the particles together. By thus confining the subsequent hydration inside the individual particles, it is possible to directly package the product without danger of caking or blocking in the package.

It is thus recognized that since the original spray-dried product is of relatively uniform particle size and the particles are suspended until they are stabilized against fusing together that the product would be substantially dust free in contradistinction to aging the spray dried detergent composition wherein the particles are in contact and become fused together, thereby requiring a subsequent crushing operation which fractures a portion of the original particles and causes the formation of dust. In addition to substantially eliminating dust formation, with the savings inherent therein, the subject process also eliminates the handling of the product in the aging step and frees a large amount of expensive storage space for additional production. The elimination of the storageaging also entails a substantial saving in labor and maintenance. Accordingly, the unit cost of the product is reduced and a more uniform product is obtained by the subject process.

Whereas the instant process can be advantageously applied to any spray-dried detergent formulation which contains hydrated components in the presence of the active constituent, it is particularly adapted to detergent compositions which are based on a non-ionic active constituent and a plurality of alkaline builder components from the group comprising tetrasodium pyrophosphate, sodium tripolyphosphate, sodium carbonate, sodium bicarbonate, the sodium silicates, and the like. The non.- ionic active constituent is generally a condensation prodnot of the lower alkylene oxides, for example, ethylene Osi is P op e ox d y e o and m tu e a '4 thereof, with a compound, or compounds, having one or more active hydrogen atoms, as for example, aliphatic mercaptans, alkyl phenols, fatty acids, alcohols, and the like. Suitable illustrative detergent compositions are disclosed in US. Patents No. 2,522,446, 2,522,447, 2,550,691, 2,572,805, 2,594,453, etc.

The detergent compositions disclosed in US. Patent No 2,550,691 are particularly adaptable to the process of this invention. These desired formulations have the following composition, all parts being by weight:

Parts Condensation product of tall oil with ethylene oxide in the ratio of 0.5 :2.3 per part of tall oil Tetrasodium py-rophosphate, sodium tripolyphosphate, or mixtures thereof (anhydrous basis) 20-60 Sodium silicate, Na O:SiO ratio of 1:2 to 1:32

(anhy ba s) "'f-.".--.----r-#-1---:-TT--f?-T" Alkaline material selected from the class consisting of sodium carbonate, sodium bicarbonate and mixtures thereof (anhydrous basis) 10-25 To the above product may be added from 0.1 to 5 parts of oarboxymethyl cellulose.

Other more specific illustrative compositions are as follows, all parts being by weight:

Condensation product of one part of tall oil with 1.6 parts of ethylene oxide 15.00 Tetrasodium pyrophosphate 4.0.00 Soda ash 20.25 Solid sodium silicate (G silicate) Na O:SiO =1:2 24.00. bbxv m thy el u os J Parts Condensation product of one part of tall oil with 1.8 parts of ethylene oxide 20 Sodium tripolyphosphate .l 40 Sodium carbonate "1.; 15 Sodium silicate (anhydrous) Na O:SiO,-,=1:3 .2 10 t hv M 4 ar o y met y c llu os 1 '1 Condensation product of one part of tall oil with 1.6 parts of ethylene oxide 15.00 Tetrasodium pyrophosphate (anhydrous basis) 40.00 Soda ash 20.15 Sodium silicate solution (water glass, 38% solids,

62% water) Na 0:Si0 =1:3.2 24.00 Carboxy methyl cellulose 0.75 Perfume (Citropene) 0.10

Condensation product of one part of tall oil with 1.5

parts of ethylene oxide ..Q 15 Sodium tripolyphosphate I. i i i 20 Tetrasodium pyrophcsphate L 20 Soda ash V i v i 20 Sodium silicate solution (38% solids) Na 0:SiO =1:3.2 24 Sodium carboxy methyl cellulose i v i 1 1 in ta t in on e a t h r ment f a. spray-dried detergent composition. Accordingly, the do: rese f rmul ti n are P e a d a la r s eated the various ways known in' the art and spray dried,

Plieferablythe anhydrous salts of the phosphates and carbonates are employed, since as stated in U.S. Patent No. 2,550,691, it was found that a better retention of the oily condensation product is obtained when the hydration is eflected in the presence thereof. In the practice of the instant invention it has also been found that the spray-dried detergent composition should preferably contain from about 14 to about 19 percent moisture for the best results, but isolated satisfactory results have been obtained outside these limits, which will vary somewhat for diiferent detergent formulations.

The following examples are further illustrative of this process.

Example 1 A small fluidizing tower, one foot in diameter and six feet high having a fluidizing-gas inlet at the bottom and having means of supplying a controlled volume of air at controlled humidity conditions, was constructed.

Fifty-pounds of a spray-dried detergent composition, preparedin accordance with formulation D of the above disclosure, was introduced into the tower substantially immediately after discharge from the spray drier. The detergent composition was fluidized for a period of about 10 minutes by passing air at about 25 to 35 C. and 0.5 p.s.i.g.vpressure upwardly through the suspended solids such that the exit air velocity was about 0.65 foot per second. Thereafter the material was passed through a 10-mesh screen and no lumps or agglomerates were found therein. Then the material was immediately packaged and subsequently found to be a free-flowing product in contradistinction to the same detergent composition which was not subjected to the fluidizing process, and wherein it was necessary to permit a static aging period of at least four hours, with subsequent crushing of the agglomerated product, in order to achieve an ultimate stability of a similar nature.

Example 2 To demonstrate the effect of the relative humidity of the fluidizing gas on the moisture content of the product and the caking and blocking tendency of the packaged spray-dried detergent composition, several experiments were run wherein the relative humidity was varied from 30 percent to 80 percent. In this test, samples of the product were prepared and fluidized in a similar manner to the procedure described in Example 1 and were packaged and stored for a short period of time, then the box tops were cut off and the material poured onto a four-mesh screen and the caked and blocked material weighed and recorded as a qualitative measure of the products, ability to remain free-flowing during normal shelf-life. The following results were obtained:

Percent Moisture Oaking and Blocking (gms) Percent Relative Content Humidity Min. 40 Min. 0 Min. 10 Min. 40 Min.

In all experiments it is apparent that the fluidized aeration provided improved results. However, it appears that when the moisture content is below about 14 percent there is insuflicient moisture to effect rapid surface hydration of the detergent particles and complete freedom from caking and blocking is not attained unless a longer aeration period is employed. This seems to be borne out, e.g., in an additional experiment at 30 percent relative humidity wherein the original moisture content was 15.8 percent and the aerated product was free from caking and blocking after and 40 minutes aeration time.

. Exdmple '3 It can be demonstrated that there is no substantial change in particle size of the detergent composition dur-. ing the course of prolonged fluidizing action, by the fact that the screen analysis remains relatively constant within the limits of experimental error:

Example 4 A larger pilot-plant fluidizing tower, about 3.5 feet in diameter and about 20 feet tall was then constructed for continuous process evaluation. The fluidizing gas was supplied to the tower through an inlet at the tip of the 45 cone by a multi-stage blower capable of delivering 450 c.f.m. at 3 p.s.i.g. The tower was provided with a perfora'tedplate and an adjustable product outlet just above .said plate as described in the above specification.

A spray-dried detergent composition, formulationD, was continuously passed through an S-mesh screen (.to preclude chance introduction of any large agglomerates which may be formed on the spray-tower walls, etc.) and fed into the top of the fluidizing tower via a bucket elevator. tained about 3.5 feet from the top of the tower by continuously removing a portion of the. treated product through the discharge port at the same rate that the material was fed into the top of the tower. The material was fluidized by the introduction of air ,at about 40 C. and a relative humidity of about-60 percent at ,a rate such that-the tower exit air velocity was about 0.95 foot per second. The average sojourn time of the material was from about 15 minutes to about 20 minutes during the course of the test. 1

I The aerated product was then packaged at a temperature of about 36 to 40 C. and the aging completed within the package without caking or blocking even when the product was exposed to extremes of temperature and humidity conditions more severe than would be required under actual marketing conditions. Control packages of non-aerated material were found to contain up to one-half of the contents in a caked and blocked condition, even under normal storage conditions, and when exposed to the accelerated storage stability test of extremes of temperature and humidity the entire contents of the package was generally blocked and caked.

Whereas the temperature of the spray-dried product introduced into the fluidizing tower was about 50 C. and the fluidizing gas temperature was about 40 C. in the above experiment, higher fluidizing gas temperatures up to at least 60 C. have been employed with substantially the same results.-

I claim:

1. In the production of spray-dried detergent compositions comprising an active nonionic o'rganic detergent constituent in the presence of a hydratable alkaline builder component, which spray-dried detergent compositions are substantially free from caking and blocking, the improvement which comprises introducing the hot spraydried detergent composition directly from the spray to'wer to a fluidizing tower and suspending said detergent under fluidizing conditions for an average sojourn time of from about 10 minutes to about 40 minutes.

2. In the production of spray-dried detergent compositions comprising the condensation product of a lower alkylene oxide with an organic compound containing at The surface of the fluidized bed was mainaos teaz.

least one active hydrog'enatom 'formulated with a plueality o hy rata e al line builder sqmn ne s wh s ay-germ geter' em" 'ti" ""bstahaany n e am s 1' a i es intl d sm the. h t" iar'a from the spray tower to: a fluidizing, K d ing said detergent under orlidit ins averagesojdurn' time 'bjf'tro'rfi about minutes to about 40 minutes.

3 The process of claim 2, wherein the spray-dried detergent composition is selected from the following formulation," all parts b ing by weight Parts Condensation product of tall oil with ethylene ox ide in the ratio'of 0.5:2.3 per part or tlallQQil-lQ Phosphate material selectedfrom the class consisting of tetrasodiumfiyrophosphate, sodium tripolyphosphate, and. mixtures thereof (anhydrous basis) 20-60 Sodium silicate, Na O:SiO r at 1 .2 (anhydrous basis)' starch u, Alkaline material selected 'f'mni' thebla an ing of sodium carbonate; sodiumbicarb'o te and mixtures thereof (anhydrous basis);

- fa r-1s 4- Th Process o a m when ti e-hot slim-fined detergent contains from about 14 to about -19 percent by weight of water, the fluidizing gas is air at a temperature offfrom about 20 to about 60? C. anda relative humidity of from about 30 to about 80 percent, and the fluidizing tower exit air velocity rate is from about 0.5 to about 1 toot per second.

5. The process of claim 4, wherein the spraydried detergent composition consists of the following formulation, all parts being by weight:

' Parts Qondensation product of one part of tall oil with 1.5

parts of ethylene Sodium tripolyphosphate Tetrasodium pyrophmphafq I 20 Soda ash I I 20 Sodium silicate solution (38% solids) Na QzSiO 3.2 I V 24 Sodium ca'rboxy methyl cellulose 1 6. In theproduction of free-flowing, spray-dried detergent compositions. wherein the non-ionic active constituent is'an'ethylenef oxide 'condensation product" and said composition contains 'a plurality of. alkaline components from the group consisting of tetra'sodiuin pyropliosphafe, sodium tripolyphosphate, sodium carbonate; sodium 'bicarbonate, and a sodium silicate, the improvement which comprises the process'of introducing the hot spray-dried detefrgent'containing from about 1410 about 19 percent by, weight of water into a tower'and sh'spendingfsaid detergent under iiuidizing conditions in azo'ne"throu'gh which a gas, inert to the detergent, is passed upwardlyat a rate sufficient to maintain the fluidized state, a'nd'the detergent is maintained in said'fiuidized state for an ave a e oj urn time o om @9131 Q- Pi 91 12 29 4 i u HH H The'process of claim 6, wherein the gas is air, at' a temperature of from about about o0", and a relat've'humidity offrorri'aboutfit) to about gercent'w. e e, l l p s; The process of claim 7, Whamthe suturi ela l fief erences Cited in the file of this patent

Claims (1)

1. IN THE PRODUCTION OF SPRAY-DRIED DETERGENT COMPOSITIONS COMPRISING AN ACTIVE NONIONIC ORGANIC DETERGENT CONSTITUENT IN THE PRESENCE OF A HYDRATABLE ALKALINE BUILDER COMPONENT, WHICH SPRAY-DRIED DETERGENT COMPOSITIONS ARE SUBSTANTIALLY FREE FROM CAKING A BLOCKING, THE IMPROVEMENT WHICH COMPRISES INTRODUCING THE HOT SPRAYDRIED DETERGENT COMPOSITION DIRECTLY FROM THE SPRAY TOWER TO A FLUIDIZING TOWER AND SUSPENDING SAID DETERGENT UNDER FLUIDIZING CONDITIONS FOR AN AVERAGE SOJOURN TIME OF FROM ABOUT 10 MINUTES TO ABOUT 40 MINUTES.