272 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (1) The bar should be the equivalent of a good toilet bar with respect to detergency, foam power, solubility and stability toward normal additives, such as perfume. (2) It should behave physically like a toilet bar with respect to wash down, lumpiness, sanding effect, cracking and wasting away on the soap basin. (3) The density should be reasonably close to soap say, 1.00 to 1.15. (4) It should have a precipitable curd with hard water that remains dispersed in reasonably hard water up to say 250 p.p.m. (5) The pH should lie between 7 and 8. To attain these conditions it is suggested that a formulatot should endeavor to choose his basic raw materials in such a way that they will resemble one another as closely as possible. Soap, for example, is a mixture of fatty acid salts of similar series. The formula should have plasticity so that it can be worked in standard or heavy duty milling equipment so that clean-cut, well-pressed bars can be made at temperatures below the decomposition points of the various ingredients. Soap, for example, is generally plodded at 100-106øF. A synthetic should be ploddable at say not over 135øF., and preferably lower. The formulatot should not be handicapped by having to work with standard soap equip- ment. Other methods are available. With respect to basic raw materials, the detergent or detergent mixture should be solid, odorless, nontoxic and light colored. Chemically it must have high detergency, foam power, be reasonably priced at less than 40 cents per pound, and be readily available from at least two or more suppliers. If the formulatot is using soap as an extender, then anionic and nonionic detergents of the generally accepted types may be used. The ones most frequently used are the alkyl aryl sulfonates, alkyl methyl taurides or alkyl sulfates. The binder is generally soap but sometimes dextrinated starch, natural gums, polyethylene glycols and other special condensation products (3) are used extensively. The manufacturing drawbacks are numerous. Moisture content and temperature are very critical. Often a difference of only 1/2 per cent moisture can cause a firm easily milled product to deteriorate into a slush, or become an impossible rubber-like mass. Sensitivity to moisture is particularly true of alkyl aryl sulfonates and frequently plodding temperatures are established on the basis of this factor (4). These latter have exceptional lime soap dispersion power but lack the full lathering qualities of the substituted amides or the fatty alcohol sulfates. The sulfated alkylolamides are also useful as foam boosters. A few typical formulations for their use are given in the refer- ences cited (3, 4) but the technical detail necessary to interpret them is beyond the scope of this paper. Another class of detergents are available or can be made available,

DETERGENTS IN TOILET BAR MANUFACTURE 273 which may have great future use. These are the soaps of modified fatty acids. For example, alphahydroxy stearic acid made by hydroxylation of the chloro derivative may have interesting possibilities (5). Also in- cluded here are the alpha-sulfonated acids which have been neutralized by organic bases to various mixtures (6, 7). These are very interesting because of their similarity to soap and their wide range of solubility and plasticity obtainable by choice of chain length and method of neutralization. Possi- bilities exist here for an all detergent bar having homogeneous characteris- tics of formulation. Some concern may be felt for the recommended type of salts used, since ammonia derived products are generally skin irritants (1). Of equal interest is the fatty acid soap where a CH2 group has been replaced by an NH group, as exemplified by a primary fatty amine con- densation with a lactone (8). This type of product is commercially avail- able, but at a cost price of about 50 cents per pound which makes it un- attractive for a large scale use. It also suffers from color and odor character- istics which are removable with diflqculty at the present time. The advantage of the product lies in the fact that the precipitated lime soaps are of a crystalline nature and meet point (4) above. It foams extremely well at pH values of 6 to 8.0 and it has trace germicidal powers due to slight amphoteric properties. In summary therefore we may say that toilet type synthetic detergent bars have reached a plateau where they are being accepted in limited amounts in the retail field at prices equivalent to that of a specialty bar. Price, within reasonable limits, is not as great a factor as quality. New materials are available which may be of great use to formulatots in the future and may provide a means of capturing a good segment of this specialty soap field. REFERENCES (1) Van Scott, Eugene J., and Lyon, J. B., •t. Invest. Dermatol., 21, 199-203 (1953). (2) Barail, Louis C., Soap Chem. Specialties, 30, 51-53, 109 (1954). (3) Becher, Paul, U.S. Patent No. 2,774,735. (4) Faier, Robert G., U.S. Patent No. 2,749,315. (5) Swern, Daniel, Ault, Waldo C., and McCutcheon, John W., "A Survey on Research Possi- bilities or Animal Fats," U.S. D. A., A1C-346, 47-50, Jan. (1953). (6) Well, J. K., Bristline, Jr., R. G., and Stirton, A. J., 7. Atrn. Oil Chemists' Soc., 32, 370-372 (1955). (7) Well, J. K., Stirton, A. J, Maurer, E. W., and Palm, W. E., Soap Chem. Specialties, 33, No. 12, 49-52, 143, 145 (1957). (8) Isbell, Arthur F., U.S. Patent No. 2,468,012.