1. Soc. Chern., 23, 321-331 (May 23, 1972) The Development of New Polyamide Resins for Easy-to-Manage Hair* R. A. BANKERT, Ph.D., H. H. ESPY, Ph.D., MARIA GRASSIE, B.S., and G. L. SCHERTZ, Ph.D.* Presented December 13, 1971, New York City Synopsis--A study of AMINOPOLYAMIDES, selected for their similarity to hair protein, shows these polymers are well adapted for the preparation of hair care RESIGNS designed to give EASILY MANAGED HAIR with improved quality. A shampoo-resistant HAIR CONDITIONER and an efficient STYLING LOTION resin have been prepared by intro- ducing reactive an,d nonreactive groups at the secondary amino nitrogen position. INTRODUCTION This paper covers a case study of laboratory experiences in the development of two types of resins to give easily managed hair that holds its position after styling. An aminopolyamide class of resins was selected for the study because of its chemical similarity to hair protein and the relative ease of changing composition to obtain desired properties. The study includes work on laboratory methods used to obtain reliable measures of product performance in a program on (a) reactive polyamides for permanently conditioning hair to give improved quality and (b) non- reactive polymers for use in styling lotions. EXPERIMENTAL AND RESULTS Shampoo-Resistant Conditioner The work on hair-reactive, shampoo-resistant polyamides for mak- ing hair easier to curl, comb, and style, and for giving improved "body" *Hercules Research Center Con, tribution No. 1579. * Hercules Incorporated, Research Center, Wilmi,ngton, Del. 19899. 321

322 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS was undertaken as the result of an observation made in a related program on permanent waving in which the curl retention of hair on mannequins was being measured after the hair had been cold waved with a cross- linking, cationic resin. The dramatic improvements in ease of combing and apparent body of the hair led to the suggestion that the polyamide be applied for this purpose alone, either with or without curlers used for waving. Although discovered while the observer's attention was directed only to curl retention, the effects of the polymer treatment on improved body and manageability are understandable, and might have been predicted. Through autoradiograms of hair treated with radioactively labeled material, this wat4r-soluble polyamide resin was shown to coat the hair fibers continuously. It then cures by reaction with hair or by crosslinking with itself to give greater stiffness and desirable effects on body or apparent fullness. The coated hair fibers should be smoother and, as a result, easier to comb and less subject to snarling. Users re- ported less "flying" during combing, indicating that the resin reduced static charge development. The program undertaken had the objectives of optimizing resin properties, of defining the effects on hair, and of es- tablishing preferred conditions for using the reactivity to assure reten- tion. Such a program must also include a thorough study to assure safety not only to hair but also to skin. In this case, extensive medical studies and in vivo use studies conducted in a related program on cold waving had previously demonstrated safety for this kind of treatment. After some preliminary work on optimum composition, the program ad- vanced rapidly to personal use studies. The resin is a low molecular weight form of an adipic acid/diethylene- triamine polyamide in which epichlorohydrin has been reacted with secondary amines to generate azetidinium functional groups that react readily with sulfhydryl groups in hair protein. For optimum results, the concentration of sulfhydryl groups in the hair is first increased by treat- ment with either sodium bisulfite or ammonium thioglycolate. For most of the work, a thioglycolate salt was used under conditions nor- mally employed for "softening" hair in a cold-waving process. Un- reacted sulfhydryl groups can be restored to their normal disulfide cross- linking form by use of a mild bromate oxidizing agent. Thus, the chemistry involved and procedures employed are very similar to the glycolate "softening" and bromate "neutralizing" steps widely used in cold-waving processes. The important difference is that a resin has been