26 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (so) U.S. Pat. 2,930,761 Brit. Pat. 867,874 Brit. Pat. 823,303 Pickthall, J. Perfumery Essent. Oil Record 51 299 (1960). Blank, I. It. J. Occupational .¾Ied. 2 6 (1960). Carter, P. J../Ira. Perfumer -4romar. 71 43 (June 1958). Burton, D. N..¾Ifg. Chemist 22 267 (1951). Dvoretskaya, 1•. M. tfolloidt•. Zh. 13 432 (1951). ttilfer, It. Drug Cosmetic Ind. 65 394 (1949). Cardew, C. V. Soap Perfumery Cosmetics 24 154-7 (1951). Brit. Pat. 767,840 Brit. Pat. 891,600 ttilfer, It. Drug Cosmetic Ind. 68 322 (1951). Mills, C. M., Ester, V. C. and Henkin, H. J. Soc. Cosmetic Chemists 7 466 (1956). Lesshafft, C. T. S. and de Kay, It. G. Drug Std. 25 45 (1957). Sagarin, E. Cosmetics: (1957) Interscience, New York. Brit. Pat. 641,203 U.S. Pat. 2,543,061 Lincoln, P. A. Chem. Prod. 17 407 (1954). Brit. Pat. 699,752 DISCUSSION MR. D. E. HERRING: Could you give any indication of how the HLB values in Table IV were obtained ? Are they in fact theoretical or determined figures ? THE LECTURER: The HLB values given in Table IV are, I believe, practica ones. I have not determined them myself. I think they would be obtained by a sub- stitution method. The theoretical values are slightly different from those given. For the C-12, 5 mol ethoxylated amine the theoretical value would be 11.0. For the C-12, 15 tool ethoxylate derivative, 15.7, and for fl•e C-18, 15 tool derivative, 14.3. One would expect this decrease between the C-12 and C-18 derivatives of equal degrees of ethoxylation as the overall molecular weight increases for the same number of tools in ethylene oxide. MR. D. E. HERRING: Since amines, and particularly ethoxylated amines, form salts in acid solution, one would anticipate the HLB value to vary with pH. Would you care to comment on this, and would you care to say whether there is a sharp change or a gradual one ? THE LECTURER: The HLB value must be considered for the system as a whole so that the amine salts will have a higher HLB than the basic materials. I have never seen any results relating pH to HLB so I just do not know whether the change is gradual or stepwise. MR. W. D. MACMILLAN: I would like to refer to Table II in which some very useful information is given concerning the variations in surface tension and wetting times in relation to the number of ethylene oxide molecules per tool of amine. I wonder, however, if you have any further information concerning the sensitization of the skin by these compounds and whether this varies according to the HLB of the ethoxy- lated amine. THE LECTURER: I can make the generalization that sensitization decreases with ethoxylation, i.e. it decreases with increased HLB. The nearer one is to the basic amines the higher the sensitization. There is a very great increase between the amine and the 2 mol ethoxylate, i.e. from the primary to the tertiary amine the sensitizing

CATIONIC EMULSIFIERS IN COSMETICS 27 effect of the tertiary amine is very much reduced compared to the primary amine. The chain length also has an effect and the lower fatty derivatives have a higher sensitizing effect than the longer chain materials. MR. C. PARRY: In Table I the reputed phenol coefficients for the quaternary ammonium compounds are given. I agree that the gram-positive organisms such as staphylococcus are more susceptible to the quarternary ammonium compounds, but the use of phenol coefficients for these quaternary ammonium compounds has been shown to be meaningless in these cases. This is indicated by the fact that British Standards Specification 3286, which is used for the evaluation of the quaternary ammonium compounds, specifies that the Rideal Walker coefficients should, in fact, be used solely for phenolic derivatives. Have you any further comments on this ? THE L•CTURER: Apart from accepting your comment in the spirit in which it is given, the figures here are given purely as a guide, and I have tried to emphasize how meaningless figures of this type can be. Apart from the method of evaluation, it is a fact that any formulated product must be considered as a whole and no results for any one component can be accepted as such. I agree that the R.W. figures in themselves do not mean a great deal in today's thinking, but they do at least allow us to form some sort of comparison between one compound and another. They are not absolute values. MR. I•. F. L. THOMAS: A number of papers have recently been written on the inactivation of germicides in conjunction with nonionic emulsifiers. Have you any experience of this, and do you feel that in relation to cattonics there is a drop in bactericidal activity in the presence of the majority of nonionic emulsifiers ? THE LECTURER: I think there is. If one considers the actioh of a quaternary to be adsorption on to the bacteria surface, it is reasonable to expect that in the presence of a nonionic the adsorption equilibrium would move towards the aqueous phase and the concentration at the surface would be reduced. In the presence of nontonics the position of the equilibrium must therefore shift away from adsorption and hence affect the efficiency of the materials as bacteriocides. MR. R. L. STEVENS: Could you please expand a little more on the subject of w/o emulsions manufactured with quaternary ammonium compounds? Perhaps some of the references which you cite give further information. TH• LECTURER: I would suggest (17) and (23). In general, the HLB value must be reduced and the materials of particular interest are the difatty quaternaries, and the ethoxylated difatty quaternaries. Long chain fatty derivatives with a small degree of ethoxylation, or short chain difatty quaternaries are materials of particular value. DR. B. A. SCOTT: IS the deposition of oil on substrate dependent on the concentra- tion of cationic ? For example, do you see a bimolecular film which is positively charged at high concentrations of cattonics ? Does the oil deposit on the substrate in these circumstances or is it affected by electrostatic repulsion ? TH• LECTURER: One can build up double layers and the quantity of material is fairly critical. On most plain surfaces the amount of material required to build up this level is very small, and so the amount of surface sensitive emulsifier used must be kept very low. The rate of deposition will be affected by the level of use but deposition will still occur at a high level of surface active material. The mechanism could then be related to degree of hydration rather than to electrostatic forces.