474 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS IV Ethyl cellulose N.10 Diethylene glycol oleate Polyvinyl pyrrolidone *Absolute alcohol .. Propellant 11 .. Propellant 12 .. 0.6% 0.7% o.7% 28.0% 35.0% 35.0% *Formulations of U.S. origin quote either SDA-40 alcohol or absolute alcohol. Industrial Methylated Spirits 74 o.p. is used in the U.K. PolyvinyZ Pyrrolido,te (VVV) Originally used as a blood plasma extender, PVP came into use for pressurized hair lacquers in the early 1950's. It fulfils most of the require- ments for a film former for hair lacquers. It is soluble in water, alcohol and alcohol/propellant mixtures, but it has the disadvantage of being hygros- copic. As supplied, it contains about 5% water, but the equilibrium moisture contents of films at 50% and 75ø/0 relative humidities are 17ø/0 and 25•o respectively. Although dried films of PVP are glossy, transparent and hard, water plasticizes the film, causing softening and tackiness which is a dis- advantage as the greatest need for a hair lacquer arises when conditions of high humidity prevail. The incorporation of some plasticizers not only improves the flexibility oS the PVP film, but also reduces hygroscopicity. Oleyl alcohol, glyceryl monoricinoleate, Cilrofiex A-2 and dimethyl phthalate (10-25% based on the resin solids) are suggested. Lano]in derivatives serve a similar purpose 5. Silicone fluids also reduce hygroscopicity when added at a rate of from 1--10% on the PVP content of the lacquer. Film formers such as shellac, dimethyl hydantoin forInaldehyde resin and ethyl cellulose, added at approximately 10ø/0 of the PVP content, stiffen the fihn and render it less hydrophilic. V PVP ........ Diethyl phthalate ...... isoPropyl myristate .... Shellac (dewaxed) .... Perfume ........ Industrial Methylated Spirits 74 o.p. Propellant 11/12 (50: 50) .. 2.2% 0.4% 0.6% 0.3ø,/0 0.s% 26.0% 70.0%

HAIR LACQUER SYSTEMS AND THEIR EVALUATION 475 vI PVP ........ Lanolin derivative .... Diethyl phthalate .... Silicone fluid ...... Perfume ........ Industrial Methylated Spirits 74 o.p. Propellent 12 ...... 2.3s% 0.30% o.6s% 0.30% o.5o% 60.90% 35.00% Vinyl Pyrrolidone/Vinyl Acetate Copolymers (PVP/VA) The copolymers of vinyl acetate with vinyl pyrrolidone 6 have film form- ing properties similar to PVP, but the vinyl acetate confers a greater degree of water resistance and reduces the solubility in water. The 60/40 vinyl pyrrolidone/vinyl acetate copolymer is commercially available. Although the PVP/VA films are less hygroscopic than PVP, they are, nevertheless, still somewhat hygroscopic and the addition of modifying agents similar to those used for PVP is necessary. The copolymers films are stiffer than corresponding PVP films, but additional film formers such as shellac, DMHF resin or ethyl cellulose may be added, as with PVP. Hair lacquer formulations based on PVP/VA are of a similar type to those in which PVP is used. Vinyl Acetate Copolymer An acidic vinyl acetate copolymer, National 28-1510 ?, provides a resin which can be modified, by neutralisation with bases, to give films of differing degrees of flexibility and sensitivity to water. The preferred base is 2-amino- 2-methyl-I, 3-propanediol and as the degree of neutralisation increases, the films produced become softer and more water-soluble. 85--95% neutrali- sation of the theoretical acidity produces a film of suitable characteristics. The following formulae are suggested as a basis for experiment • :-- VII National 28-1810 .... 2-amino-2-methyl-1, 3-propanediol Alcohol soluble lanolin .... isoPropyl myristate (cosmetic grade) Dipropylene glycol .... Perfume oil ...... SDA-40 alcohol (anhydrous) .. 3.45% 0.38% 0.90% 0.40% o.o% 0.35% 94.42%