126 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS This study was conducted with VEM resin* (3), a terpolymer of N- vinyl pyrrolidone, an acrylic-type ester, and acrylic acid (4), and the following amino alcohols were selected as the neutralization agents: AM PD--2-amino-2-methyl- 1,3-propanedioF AE PD--2-amin o-2-e thyl- 1,3-propane diol* AMP--2-amino-2-me thyl-l-propanol* AB--2-amino- 1 -bu tanol t MEA--monoethanolamine* D EA--die thanolamine* TEA--triethanolamine* MIPA--monoisopropanolamine* D I PA--diisopropanol amine* TIPA--triisopropanolamine* Properties of VEM resin (neutralized with these amino alcohols), such as pH value in ethanol solution, Sward Hardness, ethanol solubility, and hygroscopicity, were evaluated. Also, the hygroscopicity of the pure amino alcohols was determined. EXPERIMENTAL Values of pH in ethanol solution were determined in a way com- monly used in the aerosol industry. A pH meter, equipped with glass- calomel electrodes, was standardized with aqueous buffer solution, in this case, at pH 9.18. Then the pH value of the particular ethanol solution was determined. The hygroscopicity of VEM resin neutralized with different amino alcohols and also the hygroscopicities of pure amino alcohols were de- termined in a modified Blue M humidity chamber.• Relative humidity was varied from 65 up to 9270 at constant temperature 30øC (86øF). The instrument used, as well as the method, was described in another article (5). Sward Hardness was determined at room temperature (23øC) using the Sward Hardness rocker (5). Purity of the amino alcohols was de- termined by conductometric titration (6) and hy•oscopicity data were obtained by weight increase in the modified Blue M humidity chamber with approximately 1-g samples after 72 hours under constant conditions. *Barr-Stalfort Co., Niles, Ill. tCommercial Solvents Corp., New York, N. Y. *Union Carbide Corp., New York, N.Y. õBlue M Co., Blue Island, Ill.

NEUTRALIZATION OF CARBOXYLIC RESIN 127 Samples of 90% neutralized resin with various amino alcohols (in the range of 1 g of dry resin) were dried for 2 days at room temperature. Afterwards, they were placed in a circulating oven at 105øC for 4 hours and the weights of the dry samples were determined. Dry samples were then placed in the humidity chamber for 72 hours under constant con- ditions. After this period of time, the weight gain was determined with a Sauter Balance* installed in the chamber. REsuI•rs AND DISCUSSION For determining the difference in pH value of amino alcohols, 0.1M solutions were prepared in anhydrous ethanol (40-A) and also in distilled water. In addition, 3% ethanol solutions of VEM resin solids were pre- pared and each solution was neutralized to 90% with a different amino alcohol. Table I pH Values of Aqueous and Ethanol Solutions of Amino Alcohols and 3% Total Solids of VEM Resin 90% Neutralized with Various Amino Alcohols pH Value 0. IM 0.1M 3% VEM-(90% in H20 in EtOH neutralized in EtOH) AMP AB AEPD AMPD MEA DEA TEA TIPA 11.23 11 12 10 78 10 70 11 07 10 75 10 23 10 32 10.55 8 10.22 8 10.25 8 l0.23 8 10.12 8 9.80 8 9.45 7 9.30 7 96 71 65 65 67 31 66 62 Table I shows that AMP gives the highest pH value when dissolved alone or when used for neutralization. By selecting from the amino alcohols in Table I, one can obtain the desired pH value for a given per- centage of neutralization of the carboxylic resin. Corresponding pH values for VEM resin, neutralized up to 100% with different amino alcohols, are given in Fig. 1. Hygroscopicities of the ethanolamines and the isopropanolamines were determined first. Figure 2 shows big variations in the percentage of weight gain, with ethanolamine having the highest hygroscopicity and triisopropanolamine the lowest. But when these amino alcohols are used *Sauter Co., Ebingen-Wiirt., Germany.