US3186948A - Detergent toilet bars - Google Patents

Description

United States Patent 3,186,948 DETERGENT TOILET BARS William A. Sweeney, San Rafael, Caiih, assignor to dialifornia Research (Iorporation, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Feb. 27, 1961, fies. No. H592 6 (Claims. (Cl. 252-161) This invention relates to the preparation of a synthetic detergent toilet bar. More particularly, the invention has to do with the preparation of .bars or cakes for toilet and bath use based on a unique mixture of organic detergent sulfonates and sulfates plasticized with water.

It is well known that soap bars for personal use must have certain special properties, i.e., the bar must be strong and cohesive so that it will not crumble on use or break if dropped. It must have good lasting quality, so that it does not mush or slough when left in a pool of water, or wear away rapidly in use. It must produce copious lather rapidly, even in cold water, and it must leave a pleasant feel on the skin after use. A toilet bar based on detergent other than soap should have all the foregoing qualities, but, in addition, should have the ability to lather well in very hard water.

Heretofore, in order to prepare a toilet bar based on synthetic detergent, or surfactant, other than soap, it has generally been necessary to incorporate with the surfacrant an organic binding or plasticizing agent capable of modifying the physical characteristics of the detergent mass and of binding together the detergent particles into a compact, cohesive bar. As examples of binding or plasticizing agents, there can be mentioned polyhydric alcohols, partially esterified :Wllh saturated fatty acids, and other oleaginous materials, such as the higher alcohols, waxes and petroleum jelly.

It has now been found that a satisfactory toilet bar can be prepared from a special mixture of organic sulfonate and sulfate detergent material which, in the presence of a plasticizing amount of water, forms a plastic cohesive mass, from which a bar having a low slough loss, good lathering characteristics even in hard water, and low wear rate can be produced. Moreover, the aforesaid mixture can be shaped or pressed into a bar that has a pleasant feel on contact with the skin, is non-sticky, and is harmless to the human body.

The toilet bar prepared in accordance with the present invention consists essentially of a compacted detergent mixture of (1) water-soluble primary normal alky-l sulfonates having 10, but preferably 15, to 20 carbon atoms; (2) water-soluble secondary alkyl sulfates having to 20 carbon atoms; and (3) water. Further, the aforesaid organic detergent ingredients compacted into the bar are present in amounts, by weight, based on the two, of at least 50%, preferably 70%, up to 90% alkyl sulfonate, and 10% to 50% of alkyl sulfate. Preferred are the sodium alkyl sulfonates and sulfates.

The water, serving as plasticity agent, is employed in an amount sufiicient to plasticize the mixture for milling and plodding employing conventional equipment. In general, the amount of water can vary from about 5 to 20%, preferably around 1 0%, by weight, based on the total weight of the bar.

The alkyl sulfonate detergent component of the present invention is one in which the alkyl group is essentially straight chain, has a carbon content of preferably to carbon atoms, and is of primary nature, i.e., has the sulfonic acid group attached to terminal carbon atom. These snlfonates can be prepared in accordance with known methods involving the free radical addition of bisulfite ion-yielding reagent, such as sodium bisulfite, to appropriate olefin or mixtures of olefins.

Similiarly, the alkyl sulfate detergent component is one in which the alkyl group is essentially normal, or straight-chain, has a carbon content of 10-20 carbon atoms, and is of secondary nature, i.e., has the sulfate group attached to a non-terminal carbon atom. These sulfates can be prepared in accordance with known methods involving the esterification of sulfuric acid by appropriate olefin material.

A convenient source of the a-olefin for both the bisulfite ion addition reaction and the sulfuric acid esterification reaction resides in the cracking of petroleum wax, whereby a fraction of u-olefins of essentially straight-chain structure having 10 to 20 carbon atoms can be obtained, the various molecular species being present in approxi mately equal molecular proportions. Further, if desired, various smaller olefin fractions for the production of the sulfonate or sulfate can be obtained within the C -C range, as by distillation, to produce fractions of desired carbon content or molecular Weight.

The properties of the final bars are desirably modified by selection of the proper olefin fraction for either detergent component of the bar. For example, the average carbon content of the p-arafin sulfonate can be increased toward the upper limit of the specified carbon content by selecting an olefin fraction in the production of the sulfonate of 15 to 20 carbon atoms or even lg7 to 20 carbon atoms. Paratlin sulfonates of higher molecular weight or carbon content, while improving the sloughing characteristics of the bar, do not substantially impair its readiness to lather. In a similar manner the average carbon content of the alkyl sulfate component can be modified, desired. Thus, C o-c 4 C C Cm-Cgo', C -C -alkyl sulfate fractions can be employed as the sulfate component.

The alkyl sulfonates of the present invention can be prepared in accordance with the well-known bisulfite addition reaction. Bisulfite ion is added to the appropriate olefin material in an aqueous methanol or ethanol solvent at a temperature of 65 to C. and in the presence of an initiator, for example, a peroxide. Following the sulfitation reaction, a de-oiling step is performed to remove unreacted hydrocarbons. These can be removed by extraction with a light hydrocarbon, for example, pentane, or by dilution with water to eifect phase formation of the oil and a water-alcohol solution of the sulfonate, followed by separation of the phases, as by decantation.

At this stage, it is often advantageous to remove inorganic sulfate, e.g., sodium sulfate formed during reaction. Desalting is accomplished by adjusting the alcohol content of the solution to about 65 to 75 volume percent based on total volume of alcohol and water, and in such proportion as to maintain a sulfonate concentration in the range 5 to 15 weight percent of the total. Upon standing, sodium sulfate crystals precipitate and are removed by filtration. When proceeding as thus described, the content of inorganic sulfate in the sulfonate active is usually below 5%.

The alcohol is then removed from the sulfonate solution by distillation. Heating is continued to remove more water until the water content of the product is about 20 to 25 weight percent of the mixture. At this point, the product, a thick slurry which is still flowable at about C., is dropped upon a chilled roll, Whereupon the product solidifies. The material is then chipped off the roll and air-dried in a conventional dryer down to the desired water content, e.g., 8 to 10 weight percent, as determined, for example, by the Karl Fischer titration method, or in an amount calculated to give the amount of moisture desired in the finished bar.

The secondary alkyl sulfates, as stated, can also be prepared in known fashion. Reaction of appropriate a-olefin and concentrated sulfuric acid yields a mixture of monoand di-alkyl sulfates. Dialkyl sulfates and any unreacted hydrocarbons can be removed by extraction with a low boiling solvent, such as pentane or hexane. The remaining acid mono-alkyl sulfate is neutralized with a suitable base, e.g., sodium, potassium,'calcium or magnesium hydroxide. The resulting aqueous solution is then treated with alcohol to precipitate inorganic salt, for example, with twice its volume of isopropyl alcohol. The precipitated salt is removed as by filtration, and the aqueous-alcoholic solution containing the desired sulfate is dried by evaporation.

In the preparation of the paraffin sulfonate-alkyl sulfate bars of the present invention, conventional soap-making equipment and process techniques'may be utilized. For example, one method involves the steps of mechanically mixing in a soap amalgamator or crutcher the desired amount of the organic sulfonate and organic sulfate adjusted to a total moisture content of about to 25 percent. At this point various additive agents, such as perfumes and coloring or Whitening materials, may be incorporated into the mixture. It may, in some instances, be desirable to have incorporated with the combination of the specified components other materials which are compatible with the essential ingredients of the combination. These include normal primary alkyl sulfonates and sulfates containing a differing cation, e.g., potassium, ammonium, calcium, or magnesium with the preferred sodium sulfonate and sulfate. Certain other detergent actives, such as the alkylaryl sulfonates, polyoxyethylene alkylphenol sulfates, acylisethionates, and sulfonated fatty' acid monoglycerides, which are compatible with the essential ingredients of the present invention, can also be included. Similarly, certain other additives heretofore suggested in the detergent art generally may be incorporated into the bar. These include the polyethylene glycols, C C fatty alcohols, stearic acid, mineral oil, mixed fatty acid alkanolamine compounds, lauric-isopropanolamine, polyethylene glycol (4000) monostearate. After mixing, the mass is milled to produce ribbons of macroscopically homogeneous compositions. These are then compacted under pressure in a plodder, a temperature of 75 to 125 .F. being satisfactory. From the plodder, the mass is extruded in the form of a continuous rod, which is then severed into the desired pieces, from which the desired bars can be stamped. Some water is lost in the manufacturing process, and, when processing as above described, the sulfonate bars have a moisture content within about the range of 5 to 20 percent.

4% sponge has carried sufiicient detergent into the water to create a persistent foam to cover the surface entirely, the number of cycles are then recorded. Wear rate is the weight, in grams, of bar worn off in 100 strokes.

Slough test is run by leaving the trimmed bar face down in a Petri dish-lid containing 50 ml. water for 17 hours, after which any loose gel is rubbed off, and the bar allowed to dry for five hours. The loss in weight of the bar in grams is reported as slough loss.

Moldability is a property of a bar, descriptive of the cohesivenessof ingredients, especially as observed after completion of the slough loss test and wear rate test.

' This moldability property is expressed as inferior,

In the following examples, the detergent mixture of alkyl sulfates and sulfonates, the various species being present in approximately equimolecular proportions, is milled, i.e., ground to provide a homogeneous composition, and plodded with water in an amount of 10% by weight, based on the organic detergents present. The detergent material is then formed into a bar by molding in a conventional soap bar mold, the bars weighing 2 to 3 ounces and having an approximate dimension in inches of 2% x 2% x A. The bars are then cut down to 2 /2 inches by 1 /2 inches, and the faces smoothed. Water contents are determined on the shavings. Before testing, they are aged in the room at ambient temperature conditions for one week with all sides exposed to the air.

Hardness of the bar'is determined by the use of procedure described in ASTM D-217. The hardness of the'bar is measured by the depth that a standard cone penetrates the sample at a set temperature of 77 F., expressed in tenths of a millimeter. A synthetic bar falling within the hardness range of about 2 to 20 is deemed satisfactory from the standpoint of hardness.

Other characteristics of the bar, such as lather quickness and wear rate, are determined by the method of P. Becker and R. E. Compa, I.A.O.C.S., 34, 53 (1957), according to which a sponge mounted on a reciprocating arm rubs over a planed surface of the bar and then dips into a gallon container containing water of the desired hardness (usually p'.p.rn. as CaCOa). When the fair, good, or excellent. A bar of inferior moldability, although usable, is somewhat hard and brittle upon drying to equilibrium conditions. Fair moldability describes a bar which tends to crumble after the slough test. A bar remaining cohesive, but with slight tendency to cracking after the slough test is rated as having good moldability. Finally, excellent moldability is applied to a bar remaining smooth and cohesive after the testing procedure.

Example 1.Bar made from C -C sodium parafifn sulfonate and water Slough loss 0.7 gram.

Lather quickness 25 strokes.

Wear rate 17.2 grams/100 strokes Hardness 4.0. Moldability Inferior.

Example 2.Bar made from C -C sodium sec-alkyl sulfate Substantially the same procedure as in Example 1 was followed, except that a sodium sec-alkyl sulfate mixture having 10.to 20 carbon atoms was substituted for the sulfonate mixture. The resulting bar was sticky to the hand, and dissolved rapidly in water. No measurements were made on the bar.

Example 3.-Bar made from C C sodium 'parafiln sulfonate C -C sodium sec-ulkyl sulfate (10%) A sodium paraifin sulfonate detergent mixture having 15 to 20 carbonatoms in an amount of 810 grams was dry-mixed with 90 grams of a sodium sec-alkyl sulfate having 10 to 20 carbon atoms. Water grams) was milled into the dry mixture by a series of six millings. The milled material was stamped into bars. These bars were finished as in Example 1. The same performance tests as before were carried outwith the following results:

Slough loss 0.3 gram.

Lather quickness 20 strokes.

Wear rate 16.5 grams/ 100 strokes. Hardness 1.6.

Moldability Fair.

Example 4.Bar made from C -C sodium parafiin sulfonate (80%), C -C sodium sec-alkyl sulfate (20%) a V Substantially the same procedure as in Example 3 was followed, except that 720 grams of a sodium paraffin sul-' fonate mixture having 15 to 20 carbon atoms and grams of sodium sec-alkyl sulfate containing 10 to 20' The faces of carbon atoms were dry-mixed and then milled with 100 grams of water. Test results were as follows:

Slough loss 4.7 grams.

Lather quickness ll strokes.

Wear rate 19.0 grams/1G0 strokes. Hardness 4.5.

Moldability Good.

Example 5 .-Bar of (I' -C sodium parafiin sulfonate (70%) and sodium sec-alkyl sulfate (30%) Substantially the same procedure as in the previous Examples 3 and 4 was followed, except that the amount of sodium paraffin sulfonate was 630 grams, and the amount of the alkyl sulfate 270 grams. Test results were as follows:

Slough loss 4.3 grams.

Lather quickness strokes.

Wear rate 20.2 grams/ 100 strokes. Hardness 6.2.

Moldability Excellent.

la the tabulated Examples 6, 7 and 8, there is employed 21 (1 43 sec-alkyl sulfate fraction in the amounts indicated with C15C2Q sodium paraffin sulfonates, water While the sodium sulfonates and sodium sulfates have been exemplified above, other water-soluble alkyl sulfomates and secondary alkyl sulfates such as those of ammonium, potassium, calcium, and magnesium can be employed. As the cations are changed from sodium to potassium to amoniurn, the bar becomes increasingly softer, has better moldability, and increased lather quickness; on the other hand, slough loss and wear rate are increased. Conversely, as the cation is varied from sodium to calcium to magnesium, opposite eifects are noted, i.e., moldability and lather quickness suffer, while the properties of slough loss and wear rate improve.

Efiects on properties of the bar are also noted with respect to variations in average content of the alkyl groups and the number of species making up the mixture. Thus, it has been observed that as the average carbon content of the alkyl groups is increased, say, from 15 to 17, slough loss and wear rate are improved, with, surprisingly, no substantial adverse efect on lather quickness. This feature is particularly applicable to the parafiin sulfonate component of the bar.

As indicated, a convenient source of the oz-0l6fil1 employed in the preparation of the alkyl sulfonates and sulfates is the cracking of petroleum wax. The C -C out has the various species present in substantial amounts,

i.e., in approximate equimolecular proportion. A wide spread of molecular species in the bar results in a softer bar, and facilitates molding. It also has high lather quickness, but higher wear rate and slough loss. A narrower spectrum of molecular species improves wear rate and slough loss. The alkyl sulfonate and sulfate components can be present as single molecular species, but this is not preferred, since the mixture tends to be more crystalline and hence becomes more difficult to shape into a bar. Further, as indicated in the examples, certain effects are noted when the proportions of the alkyl sulfonate and sulfates are varied with respect to each other. Thus, as the secondary alkyl sulfate component is increased, molding of the mixture is easier, and lather quickness is improved, but the resulting bar is softer, with consequent higher wear rate and slough loss. Bars containing over 50% secondary alkyl sulfate are too soft and are sticky to the touch and, hence, unsatisfactory.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A synthetic detergent toilet bar consisting essentially of a compacted detergent mixture of the following ingredients: water-soluble primary normal alkyl metal sulfonates, secondary alkyl metal sulfates, and water, said alkyl groups of said detergent mixture containing 10 to 20 carbon atoms, the sulfonates and sulfate molecular species eing present in approximately equimolecular proportions, respectively; said metal being selected from the group consisting of sodium, potassium, ammonium, calcium and magnesium; said ingredient being present in an amount ranging from about 50 to 90 weight percent alkyl sulfonates and 10 to 50 weight percent alkyl sulfates based on the two, and the Water 5 to 20 percent, by weight, based on the bar; said ingredients, moreover, being the sole binding and plasticizing agents for said mixture.

2. Toilet bar according to claim 1, wherein the sulfonates and sulfates are sodium sulfonates and sulfates.

3. Toilet bar according to claim 1 wherein the alkyl sulfonates contain 15 to 20 carbon atoms.

4. Toilet bar according to claim 3, wherein the sulfonates and sulfates are sodium sulfonates and sulfates.

5. Toilet bar according to claim 3, wherein the proportions of alkyl sulfonates and alkyl sulfates range from to 98% sulfonates and 10 to 30% sulfates.

6. Toilet bar according to claim 5, wherein the sulfonates and sulfates are sodium sulfonates and sulfates.

References Cited by the Examiner UNITED STATES PATENTS 2,653,913 9/53 Van Dijck 252161 2,987,484 6/61 Lilndbcrg et al. 252-161 XR 3,001,948 9/61 Clippinger 252-l61 XR JULIUS GREENWALD, Primary Examiner.

Claims (1)

1. A SYNTHETIC DETERGENT TOILET BAR CONSISTING ESSENTIALLY OF A COMPACTED DETERGENT MIXTURE OF THE FOLLOWING INGREDIENTS: WATER-SOLUBLE PRIMARY NORMAL ALKYL METAL SULFONATES, SECONDARY ALKYL METAL SULFATES, AND WATER, SAID ALKYL GROUPS OF SAID DETERGENT MIXTURE CONTAINING 10 TO 20 CARBON ATOMS, THE SULFONATES, AND SULFATE MOLECULAR SPEICES BEING PRESENT IN APPROXIMATELY EQUIMOLECULAR PROPORTIONS, RESPECTIVELY; SAID METAL BEING SELECTED FROM THE GROUP CONSISTING OF SODIUM, POTASSIUM, AMMONIUM, CALCIUM AND MAGNESIUM; SAID INGREDIENTS BEING PRESENT IN AN AMOUNT RANGING FROM ABOUT 50 TO 90 WEIGHT PERCENT ALKYL SULFONATES AND 10 TO 50 WEIGHT PERCENT ALKYL SULFATES BASED ON THE TWO, AND THE WATER 5 TO 20 PERCENT M BY WEIGHT, BASED ON THE BAR; SAID INGREDIENTS, MOREOVER, BEING THE SOLE BINDING AND PLASTICIZING AGENTS FOR SAID MIXTURE.