US2875154A - Non-caking solid particulate detergents - Google Patents

Description

NON-CAKIN G SOLID PARTICULATE DETERGENTS Allen H. Lewis, Berkeley, .Calif., assignor to California Research Corporation, San :Francisco, Calif., a corporation of Delaware I No Drawing. Application August 1, 1952 Serial No. 302,260

4 Claims. (Cl. 252138) This invention relates to improvements in solid par compositions in current commercial use are marketedin the solid particulate form as beads, flakes, chips, scales or granules, packaged into containers such as metal drums, glass jars, wooden boxes and barrels, paper and cloth bags, and cartons. Among these various. anionic sulfonate and sulfate synthetic detergent compositions, those having as their effective detergent ingredients watersoluble salts of long-chain mono-alkyl benzene 'snlfonic acids and long-chain alkyl toluene sulfonic acids containing from 9 to 18 carbon atoms in the alkyl chain are known to be eminently suitable-for the various purposes of industrial and household use. Despite the fact that these alkyl benzene and alkyl toluene sulfonates are considered to be among the most satisfactory and efficient detergent compositions available in the trade, considerabledifiiculty is encountered in handling these. com positions by the consumer because of the tendency of thesecompositions to cake upon storage,'especially when exposed to warm and humid climatic conditions.

The occurrence of caking has been ascribed to a numher of factors: It has been said that it is caused by.-the

presence of the residual moisture in the dry detergent particles. .Another explanation is that'caking is occa 'sioncd bythe penetration of the atmospheric moisture into the container even thoough it may appear to be .perfectly Well sealed. Theories have been oifered to relate the phenomenon of caking to the particular physical structure or chemical nature of the detergent particles. Whatever be the, true cause or causes of caking,

its occurrence is: highly-undesirable. and annoying. It

interferes with the free flow of the particulate .d'etergent materialfrom the package; furthermore, lumpsof caked nited States Patent siderably to the occurrence of caking in large containers, barrels and bags, particularly when heavy paper or cloth bags containing detergent are stacked or piled on top of each other. Even in the presence of very small amounts of moisture inthe surrounding atmosphere, the weight of the detergent material occasions undesirable caking and tackiness, which may become quite annoying at the packaging plant by clogging hoppers, and thus resulting in stoppages and waste of time.

.I have found that the caking tendency of sulfonate detergent compositions can be markedly reduced and frequently completely eliminated by incorporating in the detergent composition a small quantity from about 2 to about 10% by weight, and preferably from about.-3 to about 5% by weight, of boric acid based on theentire composition. The detergent composition to which. the boric acid is added contains in each 100 partsby weight thereof from about 10 to about 95 parts of the aforementioned sodium salts of long-chain mouoalkyl benzene sulfonic acids or long-chain monoalkyl toluene sulfonic acids, the remainder being inorganic sodium salt builders.

A convenient technique for producing solid particulate long-chain monoalkyl aryl (benzene or toluene) sulfonate detergent compositions, which can bestabilized against caking in accordance with my invention, involves alkylating benzene or toluene with a long-chain olefin or an olefin polymer containing from 9 to 18 carbon atoms, for instance, polypropylene, employing a suitable efiectivealkylation catalyst such as hydrofluoric acid. The resulting long-chain (C to C monoalkyl benzene or toluene product, and preferably thatiraction thereof which contains from 12 to 15 carbon atoms in the long .alkyl'chain, is thereafter subjected to sulfonationyvith are'converte'd to sodium salts by neutralization with an aqueous solution of caustic (NaOH) or sodium carbonate. Theprevailing practice isto leave all or a part of the unreacted sulfuric acid admixed with the sulfonic acids and to neutralize the sulfonic-sulfuric acid mixture to form an aqueous dispersion or slurry of the corresponding organic sodium monoalkyl.benzene or toluene sulfonate detergent and inorganic sodium sulfate builder.

i material'arefslow to disso1ve in fthe wash Water. While jpresjence of moisture: is fprobabl'y the chief factor reflsponsible for the occurrencejot cakingjin sulfonate deterg cnt compositions, Qariother important concurring "fac! tot-is the "pressure exerted by the weight of the mass of detergent material in the package. It contributescon- Another technique for preparing detergent sodium monoallcyl benzene ortoluene sulfonates, improved or stabilized against caking in accordance with my, invention, involves condensation of benzene with chlorinated C to C acycliohydrocarbons such asarefconta'ined' in a chlorinated kerosene fraction of petroleum, in the presence of a suitable catalyst, fdrdinarilyjAlCl; The resulting miizture of C to C .monoall y1 benzenes for tolaenes is then sulfonated and neutralized in a jc'onyentionai manner, and thefinal slurry of 'monoalkyl benzene or toluene sulfonate and sodium sulfate'is .dried'and reduced to the desired particle form and size. Frequent- 1y, additional amounts of builders, e g, more'sodium sulfate and other inorganic sodiumls'alts ,such assodiuin silicate-and particularly phosphates such as tetrasodium pyrophosphate or sodium tripolyphosphate, may be added to the neutralized sulfonate slurry before drying this latter in accordance with the specifications for the ultimately desired detergent composition. The slurry built with these various sodium salts is converted to the desired solid form and particle size by an appropriate dry ing technique, for instance, by spray-drying or drumdrying.

In addition to the inorganic sodium salt builders, organic builders, in particular sodium carboxymethyl cellulose, may be added to the neutralized sulfonate slurry in order to improve its detergency characteristics.

The introduction of the caking preventive of my invention, boric acid, usually in its conventional form of crystalline flakes, into the detergent composition is preferably carried out by adding boric acid, sodium borate, or borax to the neutralizing solution of sodium hydroxide or sodium carbonate, which is then employed to neutralize the sulfonic acid mixture. The pH of the neutralized sulfonate slurry should be less than about pH=8.3 and may be as low as pH=6.0, but preferably from about pH=7.0 to about pH=8.0, in order that boric acid rather than boric acid salts be present in the final product. One may also introduce boric acid by dispersing it in the sulfonic acid mixture.

Generally, sodium salt builders and extenders, such as sodium sulfate, tetrasodium pyrophosphate, sodium polyphosphates, sodium silicates, sodium chloride, sodium carbonate, sodium carboxymethyl cellulose, do not interfere with the anti-caking effect of boric acid provided they are employed in proportions which do not occasion a too high pH of the neutralized sulfonate slurry.

If it is desired to utilize the anti-caking effect of boric acid in the manufacture of the so-called heavy-duty detergent compositions, which generally contain alkaline sodium salt builders giving to these compositions a final pH greater than about 8.3 and as high as 11.5, when used in aqueous solutions of 0.2% to 0.5% in concentration conventionally employed in the laundry practice and in houshold washing, this may be accomplished by carrying out the compounding of the detergent composition in two separate stages. The alkaline builders which would otherwise nullify the anti-caking effect because of their alkalinity are withheld, while the other ingredients of the detergent composition including the boric acid, are dried from an essentially neutral slurry formed as described hereinabovel In this way a solid, particulate, non-caking detergent intermediate composition is prepared, which can be readily handled in manufacturing equipment without tendency to stick or cake, and which can then be compounded with more alkaline builders, such as sodium tripolyphosphate or sodium carbonate, by blending the dry materials or by the use of a process such as is described in British Patent No. 584,698.

The degree of improvement in the caking characteristics obtained for each particular composition may be varied somewhat depending on the exact amount of boric acid added, the method of drying the slurry (drum-drying or spray-drying), and the proportion of the active sulfonate detergent in the slurry. A definite advantage secured by the introduction of boric acid resides in a higher moisture content which can be tolerated in the sulfonate detergent composition without the risk of excessive caking technique. have been carried out.

The first series of; tests (humiditycabinet tests) was eifected as follows: After incorporating boric acid into the detergent composition in accordance with the procedures described hereinabove, the neutralized slurry was dried to yield the desired particle form product. Weighed samples of the dried particulate compositions, screened through a No. 16 sieve and collected on a No. 200 sieve, were placed in small untreated sealed cardboard boxes (1%" x 2 /2" x 4"), and three samples of the detergent composition containing boric acid together with three samples containing no boric acid were placed in a completely random manner in a humidity cabinet, exposed to a relative humidity of about at a temperature of about F. After the exposure period of seven days, the boxes containing samples were re-weighed, and the extent of caking was determined by cutting away an entire side of the cardboard box and carefully transferring its contents onto a No. 4 sieve 4" mesh) from a minimum height. Thesieve was then gently swirled until all particles came into contact with the screen. The material which did not pass through the screen by this treatment was considered to be caked, and its weight vs. the weight of the original sample was designated the percentage of material caked. The following Table I contains the results of several of these tests carried out in the humidity cabinet.

TABLE I Eflect of boric acid as a caking-preventive as shown b humidity cabinet tests Boric Acid in percent Detergent Composi- Test tlon in each parts 7 N o. by weight Percent Cnked b y (Averweight age) Remarks monalkyl Co01a 0 G5 benzene.

60 parts Na2SO4..

40 parts sodium 2 monoalkyl Cn-Cia {40 parts sodium Boric acid intro- 3 16 duced into benzene.

60 parts M12804..- izing solution.

NaOH neutral- 40 parts sodium 3 monoa1l ylCgG1s 5 5 Do.

benzene. 60 parts Na2SO4 40 parts sodium 4..' mouoalkylCa-Ol benzene. 60 parts NazSO. {to parts monoalkyl (Cu-C15) toluene sulfonate. oil-parts NazS04 The second seriesof tests (pressure-caking tests) were carried. out as follows: Neutralized slurries of similarlyprepared long-chain C -C monalkyl benzene and toluene sulfonate detergent compositions containing from 2 to 10% by weight of boric acid were dried and reduced to the desired form and size. The dried compositions were screened through a No. 12 sieve and collected on a No. 200 sieve, and 50 gram samples were placed into brass cylinders, 2" in diameter and 3-4" high, closed by a push piston at the top. A weight which varied from 2 to 4 kilograms was applied to the piston for 5 minutes. Then the contents of the brass cylinder were pushed out. The cylinder-shape sample was dropped from a height of 1 foot onto a No. 4 screen. The ratio of the weight of the material remaining on the screen to the weight of the original sample was taken to indicate the percentage of material .eakedft TABLE II Efiect of boric acid as a caking-preventive as shown by pressure-caking rem 1 Added as borer to the neutralizing solution of N aOH.

As can be seen from the data in Tables I and II, a remarkable reduction of the caking tendency is obtained by the addition of boric acid to the sulfonate detergent compositions in accordance with my invention. In a number of tests this tendency practically disappeared in the presence of boric acid. Particularly striking is the reduction of caking and tackiness in samples of long chain C -C monoalkyl toluene sulfonates heretofore considered exceptionally susceptible to caking.

The sulfonate detergent compositions, capable of being stabilized against caking by the addition of boric acid in accordance with my invention, may also contain minor amounts of additives to improve odor, sudsing, suds stability and other characteristics thereof, such as perfumes, fatty alcohols, fatty acid alkanolamides, etc. The phrase consisting essentially as employed in the appended claims is intended to indicate the essential components of the detergent composition claimed, but does not preclude the presence of these additives.

I claim:

1. A built detergent composition in the form of small solid particles consisting essentially of about to about 95 parts by weight of a sodium salt of an alkyl aryl sul fonic acid selected from the group of alkyl benzene sulfonic and alkyl toluene sulfonic acids containing from 9 to 18 carbon atoms in the alkyl chain, sodium salt detergent builders in an amount sufiicient to bring the aggregate weight of the sulfonic acid salt and the detergent builders to 100 parts by weight and so selected from the group consisting of sodium sulfate, sodium polyphosphates, sodium silicates, sodium chloride, sodium carbonate and sodium carboxymethyl cellulose that the pH of the built detergent composition is less than about 8.3, and from about 2 to about 10% by weight, based on the aggregate weight of the sulfonic acid salt and the detergent builders, of boric acid uniformly dispersed in each particle of the detergent composition.

2. A built detergent composition as defined in claim 1, wherein boric acid is present in an amount from about 3 to about 5% by weight, based on the aggregate weight of the sulfonic acid salt and the detergent builders.

3. A built detergent composition in the form of small solid particles consisting essentially of about 10 to about 95 parts by weight of a sodium salt of an alkyl aryl sulfonic acid selected from the group of alkyl benzene sulionic and alkyl toluene sulfonic acids containing from 9 to 18 carbon atoms in the alkyl chain, sodium salt detergent builders, in an amount sufiicient to bring the aggregate weight of the sulfonic acid salt and the detergent builders to 100 parts by weight and so selected from the group consisting of sodium sulfate, sodium polyphosphates, sodium silicates, sodium chloride, sodium carbonate and sodium carboxymethyl cellulose that the pH of the built detergent composition is in the range from about 7.0 to about 8.0, and from about 2 to about 10% by weight, based on the aggregate weight of the sulfonic acid salt and the detergent builders, of boric acid uniformly dispersed in each particle of the detergent composition.

4. In the preparation of a solid, particulate detergent composition, in which the organic detergent component is a sodium salt of an alkyl aryl sulfonic acid from the group consisting of C -C alkyl benzene sulfonic and C -C alkyl toluene sulfonic acids and the inorganic components are sodium salt detergent builders, said detergent composition being produced by sulfonating a mixture of alkyl aryl hydrocarbons from the group of C to C alkyl benzenes and C to C alkyl toluenes, neutralizing the resulting sulfonation product mixture and drying said mixture to solid detergent particles, a method permitting of reducing the caking tendency of said detergent composition, which comprises introducing from about 2 to about 10% of boric acid, based on the weight of the final dry detergent composition, into the neutralizing solution for the sulfonation product mixture, neutralizing said sulfonation mixture to a pH of less than about 8.3, drying the neutralized mixture to small particle size and compounding the resulting dn'ed particles resistant to caking with sodium salt detergent builders capable of imparting a pH from about 8.3 to about 11.5 to an aqueous solution of the resulting blend, ranging from 0.2% to 0.5% in concentration.

References Cited in the file of this patent UNITED STATES PATENTS 2,119,970 Smith June 7, 1938 2,480,579 Holuba Aug. 30, 1949 2,541,248 Hibbs Feb. 13, 1951 2,579,380 Funderburl: 18, 1951

Claims (1)

1. A BUILT DETERGENT COMPOSITION IN THE FORM OF SMALL SOLID PARTICLES CONSISTING ESSENTIALLY OF ABOUT 10 TO ABOUT 95 PARTS BY WEIGHT OF A SODIUM SALT OF AN ALKYL ARYL SULFONIC ACID SELECTED FROM THE GROUP OF ALKYL BENZENE SULFONIC AND ALKYL TOLUENE SULFONIC ACIDS CONTAINING FROM 9 TO 18 CARBON ATOMS IN THE ALKYL CHAIN, SODIUM SALT DETERGENT BUILDERS IN AN AMOUNT SUFFICIENT TO BRING THE AGGREGATE WEIGHT OF THE SULFONIC ACID SALT AND THE DETERGENT BUILDERS TO 100 PARTS BY WEIGHT AND SO SELECTED FROM THE GROUP CONSISTING OF SODIUM SULFATE, SODIUM POLYPHOSPHATES, SODIUM SILICATES, SODIUM CHLORIDE, SODIUM CARBONATE AND SODIUM CARBOXYMETHYL CELLULOSE THAT THE PH OF THE BUILT DETERGENT COMPOSITION IS LESS THAN ABOUT 8.3, AND FROM ABOUT 2 TO ABOUT 10% BY WEIGHT, BASED ON THE AGGREGATE WEIGHT OF THE SULFONIC ACID SALT AND THE DETERGENT BUILDERS, OF BORIC ACID UNIFORMLY DISPERSED IN EACH PARTICLE OF THE DETERGENT COMPOSITION.