US2298651A - Particulate solid detergent - Google Patents

Description

Patented Oct. 13, 1942 PARTICULATE SOLID DETERGENT Nicholas N. T. Samaras and Jay 0. Harris,

Dayton, Ohio, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application December 7, 1940, Serial No. 369,124

11 Claims. (CL 252-161) The present invention relates to new particulate solid detergent compositions in the form of scales. flakes or chips, which are free-flowing and substantially non-hygroscopic and non-caking.

Many of the commercial preparations of detergent compositions, and in particular, detergent compositions comprising water-soluble salts of alkylated aromatic sulfonic acids, exhibit the undesirable property of wetting down on exposure part of our co-pending application Serial No.

183,509, filed January 5,- 1938. g

The principal object of the present invention is to provide a detergent composition in particulate solid form which shall be characterized by especially high detergent efliciency and which shall dissolve rapidly in water, be substantially unaffected by atmospheric moisture conditions normally prevailing in different geographical localities, and which shall be substantially free of fine particles that are readily borne by circulating air currents in the home and substantially free from any tendency to disintegrate into finer particles on standing or shaking. The detergent composition shall be of stable particulate form, have a low apparent specific gravity and be free from fine dust particles and shall be stable and free from caking tendency under prevailing atmospheric conditions.

In accordance with the present invention it has been discovered that a detergent composition conforming in a remarkable degree to the specifications outlinedin the foregoing object can be made by drum-drying an aqueous solution or a uniform or homogeneous, suspension comprising sodium sulfate and certain alkylated aromatic hydrocarbon sulfonic acid salts which are specifled hereinafter. By observing certain ratios of constituents and conducting the drying in such a manner as to leave a determinate moisture content in the product, free-flowing relatively nonhygroscopic particulate solid detergentcompositions are obtained in the form of uniform flakes, scales or'chips, having an apparent specific gravity within the range of 0.2 and 0.5 and preferably within the range of 0.3 to 0.4.

The ratio. of sodium sulfate to the salt of the alkylated aromatic hydrocarbon sulfonic' acidv may be varied widely provided at least approximately 20% sodium sulfate is present, but compositions having optimum non-caking characteristics and detergent efflciency and which are at the same time of low apparent specific gravity and free from tendency to disintegrate are those comprising 20% to 80% by weight of sodium sulfate and preferably 35% to 65%, or the even narrower range of 40% to while the content.

of alkylated aromatic sulfonic acid salt is 80% to 20% and preferably to 35% or 60% to 40%. Small proportions of additional detergent builders such; as magnesium sulfate may be present without changing the properties of the composition substantially. Sodium sulfate may be replaced by sodium carbonate in such compositions up toabout 50% or more of the detergent builder content (see, for example Detergent Mix B hereinafter) with but slight changes in general characteristics but with significant changes in the alkalinity of the detergent composition, that is, a detergent of this class containing sodium carbonate is slightly alkaline but one containing only sodium sulfate as the constituent other than the alkylated aromatic-hr drocarbon sulfonic acid salt is approximately neutral in reaction. Similarly. some of the sodium sulfate may be replaced by builders such as tetrasodium pyrophosphate, borax and the like.

when a greater proportion of sodium sulfate is present than is specified hereinabove, the

product is too hydroscopic and cakes too readily, produces too great a proportion of fines or dust on drying and is characterized by decreased detersive efliciency. sulfate produces a product that is gummy and is likewise hydroscopic. Fines are undesirable since they produce dusting. which is likely to cause sneezing and irritation, andproducts con- A smaller content of sodium taining fines cake much more rapidly than products of uniform-particulate size.

In the preparation of the detergent composition, the composition should not be dried to the total exclusion of moisture. The particulate solid composition should have a moisture content of fromapproximately 1.0%.to 5.0% water. observing these limits undesirable fragmentation or disintegration into fine powder' is inhibited and the tendency to produce dust or undesirable fines on standing or shaking is eliminated. Com-= that certain specific proportions of sodium sulfate and the alkylated aromatic hydrocarbon sulfonic acid salt must beobserved to obtain a particulate product which on drum-drying will be substantially stable, free-flowing and no'n-cak-- ing, but that the moisture content of the final product must also be controlled since the combined moisture has a binding or cohesive effect on the individual particles and prevents absorption or liberation of substantial proportions of moisture which are accompanied by disintegration or crumbling of the particles. The low apparent specific gravity of the product is also of importance since this is connected with the tendency of the particles to absorb and liberate water without wetting'down and caking and without disintegration or crumbling of the individual particles. Particulat detergents of this type having a lower apparent specific gravity than about 0.2 are unstable, friable, and disintegrate on standing into finer particles and dust.

The salts of alkylated aromatic hydrocarbon sulfonic acids which are contemplated for use in this invention are water-soluble, particularly alkali-metal, salts of alkylated benzene sulfonic acids in which at least one alkyl group contains from 8 to and particularly 11 to 15 carbon atoms and mixtures thereof. Sodium salts of alkylated benzene sulfonic acids are preferred. Such salts of alkylated aromatic hydrocarbon sulfonic acids and methods for their preparation are described in Kyrides Patent No. 2,161,174

result in afree-flowing, non-hygroscopic solid.

gsimilarlyyon grinding dodecylbenzene sodium sulfonate with an equal weight of a'mixture of equal parts by weight of sodium chloride and sodium benzene monosulfonate. the powdered product caked to a semi-solid after less than six days of exposure to 60% relative humidity.

However, on drum-drying aqueous solutions or homogeneous suspensions of the alkylated aromatic sulfonate containing sodium sulfate, according to the present invention, the caking and deliquescing of the detergent is unexpectedly eliminated and the product po the other desirable properties referred to herein.

A great variety of detergent composition have been made with a mixture of dodecylbenzene and tridecylbenzene sodium sulfonates and an equal part by weight of sodium sulfate or other salt in eflorts to produce a free-flowing noncaking and non-crumbling particulate detergent composition. These compositions were made by drum-drying aqueous solutions or suspensions of the desired composition, according to the method of the present invention. The dried particulate compositions were then exposed for varied periods to atmospheres having arelative humidity and in our copending application referredto hereinabove. Alkali-metal salts of sulfonic acids of undecyl, dodecyl, tridecyl, tetradwyl and pentadecyl substituted benzene, toluene, xylene and similar aromatic hydrocarbons of the benzene series, as well as their isomers and mixtures thereof, are included within the ambit of the invention.

Heretofore, in' the manufacture of detergent compositions from water-soluble metallic salts of alkylated aromatic sulfonic acids in which the alkyl group contains more than 8 and less than 16 carbon atoms, great difiiculty and inconvenience in handling were experienced because of the tendency of the materials to cake and deliquesce. Attempts to remedy or eliminate this undesirable property of the products by the simple mechanical admixture of anhydrous sodium sulfate with the water-soluble alkali-metal salts of said alkylated aromatic sulfonic acids did not of or more. The composition made with sodium sulfate in this manner retained its particulate iorm, was free-flowing, and was dry in appearance after six days. Compositions made with tetrasodium pyrophosphate, borax and sodium silicate, respectively, in place of the sodium sulfate, were caked at the end of six days, the silicate mixture being a solid mass. The percentages of moisture absorbed in the last three I cases were not substantially different, although it was higher in all cases than that of the composition containing sodium sulfate, yet the degree and character of the caking was diflerent and was most marked in the case of sodium silicate.. The problem is obviously not solely one of moisture absorption alone. Furthermore, a great variety of salts which mightv otherwise appear useful for the purpose of preventing caking of the detergent compositions could not be used because of their adverse effect on the detergent characteristics of the composition. In this respect sodium sulfate is unique in that it does not decrease substantially the detergent efiectiveness 0f the alkylated aromatic sulfonate in the composition and has a most desirabl efiect on the physical characteristics of the resulting dried product. f

It is believed that under the conditions of drying specified in the present invention the sodium sulfate is present in the product in a form analogous to the beta form of anhydrous sodium sulfate and that in the product the alkali-metal salt of the alkylated aromatic hydrocarbon sulfonic acid prevents transformation of the beta form to the alpha form. It is known (see J. W.

' Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry," London, Longmans,

Green 8: Co., vol. II, 1927, page 661) that the.

beta form of anhydrous sodium sulfate does not hydrate while the alpha form combines immediately with water at 25 and that hydration of the beta form starts only when it has passed into the alpha form.

Any suitable apparatus and method of drumdrying aqueous solutions or suspensions of the alkylated benzene sulfonate and sodium sulfate may be used provided the process is adjusted to obtain a particulate product having an apparent Industrial Chemistry by Emil Raymond Riegel,

third edition, New York, Reinhold Publishing Corp., 1937, page 702 et seq., Elements of Chemical Engineering by Walter L. Badger and Warren D. McCabe, second edition, New York, McGraw-Hill'Book Co., 1936, page 294 et seq., and similar books. The invention is not limited to any specific method of drum-drying whereby a product of this character is obtained. However, preferred methods are illustrated herein,- after.

As specific embodiments of this invention portions of aqueous suspensions of a detergent hereinafter called Detergent Mix A consisting of 100 parts of a mixture of dodecylbenzene and tridecylbenzene sodium sulfonates, 100 parts of an- Exwu I Detergent Mix .4

Concentration of solution 20%. Temperature of solution fed to drier 90 C. Drum spacing (aperture between rnllc 0.006111011. Roll temperature 127 C. Speed of rolls. 1.25 R. P. M. .Steam pressure; 50 lbs/in.

Flake thickness of dried product.-. 0.006 inch. Moisture of dried, product 8.2%. Apparent specific gravity-- 0.2729.

hydrous sodium sulfate and 4 parts of hydrated magnesium sulfate (Epsom salt), having concentrations of 10 to 60% by weight of solids and preferably 30% to 50% solids, were dried in a laboratory Bufiovak atmospheric drum drier.

and briefly. consists of two stainless steel rolls of equal dimensions tangentially mounted and rotating in opposite directions at the same rate of speed. The rolls are heated internally by means of steam under pressure. The liquid to be dried is flowed on the rolls in any convenient manner, and the thickness and nature of the dried product determined by the temperature of the rolls,

a the roll speed and aperture between the rolls,

which may be varied. The resulting dried products were found to possess apparent specific gravities varying between 0.2 and 0.5. The dried and contents were dropped fifty times from a height of 3 inches and the volume of the compacted detergent composition noted at a temperature of 30 C. Twenty-five grams of water is known to occupy a volume of 25.1 c. c. at 30 C.

The volume of grams of water at 0. divided by the volume of the same weight of the detergent mixture at 30 C. is the apparent specific gravity of the detergent composition.

The caking test as employed in this application was conducted in the following manner. Definite weighed portions of the detergent under test were placed in open containers which in turn were placed in jars containing saturated aqueous solutions of appropriate inorganic salts in contact with an excess of the solid phase chosen so as to produce 60%, 85% and 93% relative humidities. The jars containing the detergent were then tightly closed and allowed to stand for six days, at the-end of which time they were opened and the. condition of the detergent noted as to increase in weight and whether or not it had caked or remained free-flowing.

The non-hydroscopicity and improved properties of the new product will be apparent from the following specific examples.

Such a drier is described in the books hereinabove cited Six-day constant humidity tostsz' Relative humidity.60% 93% Percent moisture 1.2 3.1 2. absorbed. Conditionaftertest. Dryandiree- Dryandfree-Dry and freeflowing. flowing. flowing.

EXAMPLE II Detergent Mix A Concentration of solids in suspension 50%. Temperature of suspension fed to drier 70 C. Drum spacing (aperture be- ,tween rolls) 0.021 inch. Roll temperature. 121 C. Speed of rolls 4 R. P. M. Steam pressure 30-32 lbs/in". Flake thickness of dried v product 0018-0022 inch. Moisture in dried product--. 2.8%. Apparent specific gravity 0.3586.

Six-day constant humidity tests:

Relative humidity" 60% 85% 93% Percent moisture 1.4 2.4 2.4

absorbed. Conditionaiter test. Dry andfree- Dryandfree- Dry and freeflowing. flowing. flowinz.

EXAMPLE III As further specificiembodiments of the present invention, portions of aqueous suspensions of a detergent composition hereinafter designated as Detergent Mix B consisting of parts of a mixture of dodecylbenzene and tridecylbenzene sodium sulfonates, 60 parts of anhydrous sodium sulfate, 40 parts of anhydrous sodium carbonate and 4 parts of hydrated magnesium sulfate (Epsom salt), having concentrations of 10% to.

60% by weight of solids and preferably 30% to 50% solids, were dried in a laboratory Buflovak drum drier as above.

It is important that the sodium sulfate and alkali-metal salt of the alkylated aromatic hydrocarbon sulfonic acid be present in solution before drying or be in the form of a homogeneous uniform suspension or slurry; otherwise products which cake in masses throughout the batch are likely to result. I

Preferably the compositions for use according to this invention are such as contain from 20% to 80% and preferably 40% to 60% or 35% .to 65% of alkylated aromatic hydrocarbon sulfonate. Such compositions are, for example, represented by the foregoing Detergent Mix A and Detergent Mix B, or by the following compositions, which can be drum-dried according to the method disclosed herein. All proportions stated are in parts by weight of anhydrous materials.

Exams: Sodium sulfate 36 Sodium carbona 24 -Alkylated aromatic hydrocarbon sulfonate-.. 4g

zene sulfonic acids having alkyl groups containing at least 11 and less than 16 carbon atoms 40 Sodium sulfate 58.5 to 59.0 Magnesium sulfate 0.5 to 1.0

EXAMPLE VIII Parts Sodium salts of a mixture of alkylated benzene sulfonic acids having alkyl groups' containing at least 11 and less than 16 carbon atoms 40 Sodium sulfate 59.5 Diethylene glycol 0.5

The diethylene glycol which is present in the compositions 'of Examples V, VI and VIII is used to prevent dusting of any, fine particles originally formed as a result of imperfect control of particle size in the drum-drying operation and to control to some extent the absorption of moisture. It may be replaced by triethylene glycol or higher polymers of ethylene glycol or may be omitted.

Examples V and VI which contain a smaller added proportion of magnesium sulfate than other disclosed products are particularly suitable for preparations made by dissolving or homogeneously suspending the materials in water containing some original hardness. The hardness of the water, representing magnesium and other metal salts, will be found in the final drumdried product. When the water used for this purpose is soft or distilled water a'greater proportion of magnesium sulfate will be required to compensate for the magnesium salts that are absent from the water. Generally from about 0.25 to 2.0% magnesium sulfate (anhydrous basis) or an equivalent amount of hydrated or anhydrous magnesium chloride is preferred in the final dried product. v

The purpose and effect of the small proportion of magnesium salts in the compositions of the invention are described in the applications of Jay C. Harris, Serial No. 192,077, filed February 23, 1938 and the continuation-in-part of said application, Serial No. 368,225, filed December 2, 1940. The magnesium salt is not necessary to obtain a free-flowing noncaking product but is desirable to provide products of improved detergent properties.

By operating according to the present invention a substantially uniform noneaking, freeflowing, particulate detergent composition can be obtained. which is not the case when the watersoluble salt of the aromatic hydrocarbon sulfonic acid is dried in a mass and mechanically mixed with sodium sulfate or when a solution of the aromatic hydrocarbon sulfonic acid salt and sodium sulfate in indiscriminate proportions is dried in a mass and then disintegrated mechanically by grinding. Caking characteristics cannot be controlled by purely empirical methods, as is evident from the foregoing description.

It is to be understood that the invention'is not to be limited by the specific examples hereinabove set forth as they are to be understood as illustrative only. The invention is limited solely byv W the following claims.

' We claim:

l. A non-caking, free-flowing particulate solid detergent, composition having anapparent specific gravity of about 0.2 to 0.5 and a moisture content of about 1.0'to 5.0% obtained by drumdrying an aqueous solution or homogeheous aqueous suspension, the solid constituents of which comprises. mixture of 35 to 65 parts by weight of sodium sulfate and 65 to 35 parts by weight of a water-soluble salt of a monoalkylsubstituted aromatic hydrocarbon sulfonic acid selected from the group consisting of watergravity of about 0.2 to 0.5 and a moisture content of about 1.0 to 5.0% obtained by drumdrying an aqueous solution or homogeneous aqueous suspension, the solid constituents of which comprise a mixture of 35 to 65 parts by weight of sodium sulfate and 65 to 35 parts -by weight of an alkali-metal salt of a monoalkyl-substituted aromatic hydrocarbon sulfonic acid selected from the group consisting of alkali-metal salts of monoalkyl-substituted benzene, toluene and xylene sulfonic acids, the substituted alkyl groups of which contain at least 11 and less than 16 carbon atoms, to each parts by weight of the solid constituents.

3. A non-caking, free-flowing particulate solid detergent composition having an apparent specific gravity of about 0.2 to 0.5 and a moisture content of about 1.0 to 5.0% obtained by drum-drying an aqueous solution or homogeneous aqueous suspension, the solid constituents of which comprise a mixture of 35 to 65 parts by weight of sodium sulfate and 65 to 35 parts by weight of a watersoluble salt of a monoalkylated benzene sulfonic acid,-the alkyl group of which contains at least 11 and less than 16 carbon atoms, to each 100 parts by weight of the solid constituents.

4. A non-caking,'free-fiowing particulate solid detergent composition having an apparent specific gravity of about-0.2 to 0.5 and a moisture content of about 1.0 to 5.0% obtained by drum-drying an aqueous solution or homogeneous aqueous suspension, the solid constituents of which comprise a mixture of 35 to 65 parts by weight of sodium tain at least 11 and less than 16 carbon atoms,

to each 100 parts by weight of the solid constituents.

6. A non-caking, free-flowing particulate solid detergent composition having an apparent specific gravity of about 0.2 to 0.5 and a moisture content ofabout 1.0 to 5.0% obtained bydrum-drying an aqueous solution or homogeneous aqueous suspension, the'solid constituents of which comprise the following substances in approximately the'following proportions by weight: 60 parts of sodium sulfate and 40 parts of sodium salts of a mixture of monoalkylated benzene sulfonic acids, the alkyl groups of which contain at least 11 and less than I 16 carbon atoms, to each 100 parts of the solid constituents.

7. A non-caking, free-flowing particulate solid detergent composition having an apparent specific gravity of about 0.2 to 0.5 and a moisture content of about 1.0 to 5.0% obtained by drum-drying an aqueous solution or homogeneous aqueous suspension, the solid constituents of which comprise the following substances in approximately the following proportions by weight: 36 parts of sodium sulfate, 24.parts of sodium carbonate and 40 parts of sodium salts of a mixture of monoalkylated benzene ,sulfonic acids, the alkyl group of which contains atleast 11 and less than 16 carbon atoms, to each 100 parts of the solid constituents.

8. A non-caking, free-flowing particulate solid detergent composition having an apparent specific gravity of about 0.2 to 0.5 and a moisture content of about 1.0 to 5.0% obtained by drumdrymg an aqueous solution or homogeneous aqueous suspension, the solid constituents of which comprise the following substances in approximately the following proportions by weight: 100

parts of sodium salts of a mixture of dodecylbenzene and tridecylbenzene sulfonic acids, 100 parts of anhydrous sodiumsulfate, and 4 parts of hydrated magnesium sulfate, to each 204 parts of the solid constituents.

9. A non-caking, free-flowing particulate solid detergent composition having an apparent specific gravity of about 0.2 to 0.5 and a moisture content of about 1.0 to 5.0% obtained by drum-drying an aqueous solution or homogeneous aqueous suspension, the solid constituents of which comprise the following substances in approximately the following proportions by weight: 100 parts of sodium salts of a mixture of dodecylbenzene and tridecylbenzenesulfonic acids, parts of anhydrous sodium sulfate, 40'parts of anhydrous sodium carbonate and 4 parts of hydrated magnesium sulfate, to each 204 parts of the solid constituents.

10. A non-caking, free-flowing particulate solid detergent composition having an apparent specific gravity of about 0.2 to 0.5 and a moisture content of about 1.0 to 5.0% obtained by drumdrying' an aqueous solution or homogeneous aqueous suspension, thesolid constituents of which comprise thefollowing substances in approximately the following proportions by weight: 58.5 parts of sodium sulfate, 40 parts' 'of sodium salts of a mixture of monoalkylated benzene sulfonic' acids, the alkyl groups of which contain at least l1 and less. than 16 carbon atoms, and 0.5 parts of magnesium sulfate (anhydrous basis), to each 99 parts of the solid constituents.

11. A non-caking, free-flowing particulate solid detergent composition having an apparent specific gravity of about 0.2 to 0.5 and a moisture content of about,1.0 to 5.0% obtained by drumdrying an aqueous solution or homogeneous aqueous suspension, the solid constituents of which comprise the following substances in approxi-- mately the following proportions by weight: 59.5 parts of sodium sulfate, 40 parts of sodium salts \of a mixture of monoalkylated benzene sulfonic acids, the alltyl groups of which contain at least 11 and less than 16 carbon atoms, and 0.5 part by weight of diethylene glycol, to each100 parts of the solid constituents.

NICHOLAS N. 'r. SAMARAS.. JAY c. HARRIS.