VINYL COPOLYMER IN THE COSMETIC COSMOS 297 !' :5: .... 75i• :- ..::. :... a. 2::: ":.:j . ....,, . . •: .......... 4& :. .2?" '"•?•'•. ' ?.)1%. •,•7:z:.' • .::,.' .'" • •-. . . . .... • • .,.-' :. }•!:: "::: i- t :'•:5•,..::..•.•5• ...... "%': .•? • ' '-' ß ....... •: ...'% .•.... . . . ...... :...::. .[ ,......., ................... Figure 8.•A model showing the molecular configuration of National's Resyn 28-1310. out upsetting solvent solubility properties. Thus, to prepare an alcohol solution of the vinyl copolymer which will dry to films soluble in tap water, simply add AMPD to the finished solution or to the alcohol before prepara- tion of the solution, whichever is more convenient. Figure 9 shows the chemical structure of AMPD as well as a suggested formula depicting the salt formation. Table 1 shows the effect on the copolymer's film properties of varying the neutralization with AMPD. Note that the aminohydroxy compound acts as a plasticizer for the resin since the Sward Rocker Hardness values de- crease. CH• I HOCH.,--C--CH.,OH I NH., "AMPD" 2-Amino-2-Methyl-l,3-Propanediol -- FCH.,--•H 1 -- + CH• I L COOH_I HOCH.,--C--CH•OH 4n n ] NH,., _ q_ --FCH•--CH--CH•--CH-] [- CHuOH-] I ' H I , [ , H/ L OCOC • COO_! H•N--•--C • L cnonj Water-Soluble Amine Salt Figure 9.

298 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS TABLE 1 Water Solubility of Per Cent Sward Rocker Film Air Dried Neutralization Hardness Value 1 Week at 72øF. 0 44 Poor 50 42 Poor 70 40 Fair 80 32 Good 90 30 Excellent 100 24 Excellent 110 18 Excellent 125 16 Excellent Sward rocker is a method for measuring surface hardness of a film in relation to plate glass which is given a value of 100. It indirectly measures flexibility (i.e. materials which are soft are also generally flexible). Figure 10 depicts the solubility characteristics of cast films. Dye has been added to the coatings to make the properties more easily discernible. UNNEU•A•IZE.D: '•N•T•'ED. UNNEUTRALIZ[.• TAP ': .'•ATER [..:TAP •ATER: •5"• •N Figure 10.--Solubility characteristics of cast films. 'The first sample shows the relative insolubility of the unneutralized resin in tap water. The second sample is 90 per cent neutralized resin and it dis- solves readily in tap water. The third sample shows the solubility of the unneutralized resin in a typical shampoo solution.* This data is useful when considering the problems of formulating to meet .consumer requirements. Thus, while the film dissolves readily in shampoo, it is possible to build in an extra safety factor by neutralizing partially or ,completely to provide a measure of water solubility. * Author's Note: The difference in color between second and third solutions is caused color of shampoo combining with that of dye.