POLYMER EVOLUTION--FROM NATURAL TO SYNTHETIC 39 light, for 2« yr. We have not found any good use for the gelation by multivalent cations. MR. M. J. Roox': How does Viscofas resin differ from the GAF Gantrez resins? MR. McKEE: Our basic linear resins are fairly similar, but probably differ in their viscosity specifications. As far as we know, GAF do not have a cross-linked grade, and they do not have special terpolymers for thickening latices and cationic emulsions. There is no Gantrez equivalent to our extremely low viscosity dispersion grade we are, of course, also using this grade as the basic polymer for the manufacture of very low viscosity esters for hair sprays. MR. M. J. RooT: Have you done any corrosion xvork with Viscofas resins in hair spray formulations packed in tinplate cans? MR. McKEE: Corrosion work with the present series of hair spray resins is noxv under way, but we do not have results as yet. DR. P. RoT•cIN: Can insolubilization of these polymers in the presence of poly- valent ions be arranged so that the insolubilization does not take place until after a film has been formed. One can then have, let us say, an aqueous solution of the polymer with a polyvalent ion present which does not become insoluble until the film dries. MR. McKEE: This is quite possible, although if you mix a polyamine or polyol with Viscofas in solution the system would probably have a limited pot life. Some film cure might occur on drying at normal temperature but heating would be required in most cases. In the case of polyvalent metal ions of the type which readily crosslink with Viscofas you would get precipitation in solution. DR. S. D. GERSHON: What is the basis for considering the polymer alternating methyl vinyl ether maleic anhydride rather than the multitude of possible variants that you could get if you mixed those two components, even in equal molecular quantities? MR. McKEE: I am solely concerned with possible applications for the resins. Our chemists have designed the resin and are quite certain that it is a 1:1 alternating polymer. DR. H. D. MuNRo: You suggested that your polymers were incompatible with surfactant materials, such as coconut dialkylolamide. Could you just confirm that this also applies to the linear version of the polymer? I would agree with this statement and have found that PVP is superior to your polymers in the case of complex formulations involving both surfactant materials, alcohol and water. Perhaps you could suggest a form of this polymer which would be similar in behaviour to PVP. MR. McKEE: I did not say that they are completely incompatible with surfactants because we have prepared quite nice shampoo gels. I did say that when you add these alkylolamide foaming agents you have to take great care. These tend to precipitate unless the preparation is very carefully carried out. In general the polymers are com- patible with surfactants, but patience and good formulating are required. DR. H. D. MuNRo: Would you agree with the statement that the polymer is not incompatible with surfactants, even if the surfactant concentration was in excess of 50% ? MR. McKEE: We have never gone up as high as 50%.

4O JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS DR. H. D. MUNRO: Folyvalent cations can precipitate these polymers. I take this to mean calcium and magnesium ions and what sort of concentration? MR. McKEE: Calcium and magnesium ions are quite compatible with the linear grades of Viscofas. DR. H. D. MUNRO: SO by polyvalent cations you refer only to certain metals? MR. McKEE: There are only certain multivalent ions which cause precipitation, for instance 10% calcium chloride solution is compatible with 10% solution of linear Fiscofas whereas addition of ferric chloride solution would cause gel formation. MR. I{. M. GODFREY: In your hair cream formulations one presumes that the T.E.A. is the neutralising agent. Have you studied the effect of neutralizing with these ethoxylated amines and what is the effect of the ethylene oxide chain links? MR. McKEE: We mentioned Ethorneen C25, and we have looked at some of the other Ethomeens, C12 and 15 series, I believe. One of the troubles with the study of the applications of this product, as I have already mentioned, is that we have to limit our work on each application because there is such a vast number of applications in which we feel our polymers will be useful and we are trying to touch on them all. MR. S. G. Hoe}i: Regarding the formulation in page 34 i •vas wondering whether you had any stability differences if the addition varied. In other words, your water and oil phases were mixed and then your neutralization phase was added last, forming a sort of a dispersion before your neutralization occurred. MR. McKEE: In the various cosmetic formulations tried we have varied the methods of mixing the ingredients, and we have found that for certain formulations one method of addition is better than another. In general, the water phase is usually gelled before addition of the oil phase. In this case you will notice that we have mixed propylene glycol with the water before we added MVE/MA, and this seemed to give us a much more stable product. We think that the stability was probably due to Viscofas cross linking with the propylene glycol. The system gave a very nice hair crealll. MR. I. R. GUCKLHORN: Have you tested any cosmetic preservatives in aqueous Viscofas systems, or do they not need preservation? MR. MCKEE: We have added n-propyl-p-hydroxybenzoate in almost every case. VV'hether we added the correct level for prevention of bacterial attack I would not like to say, but the amount added seemed to improve the viscosity stability. We do not think that this had anything to do with the prevention of bacterial attack because, as far as we know, these resins do not encourage bacterial growth. The additive appeared to be acting either as a uv stabiliser or an anti-oxidant. MR. P. C. RECORD: Could you give further details of methods of improving the stability of Viscofas solutions against uv degradation? MR. McKEE: We think we have overcome uv instability but we are not yet sure. Our initial work was done with EDTA plus various uv stabiliser systems, both com- mercially available and otherwise, but recently we decided to try other complexing agents other than EDTA, and we chose Calgon. %Ve have found a tremendous im- provement in uv stability with the latter.