POLYVINYLPYRROLII)ONE IN COSMETICS 205 •ig. 9. View of the spray dryer for the final recovery of solid polyvinylpyrrolidone. The combination of these somewhat remarkable properties has encour- aged cosmetic chemists to evaluate polyvinylpyrrolidone for a wide variety of uses employing these special characteristics. It is not suggested that polyvinylpyrrolidone be used simply as a water-soluble binder and thickening agent, although it is suitable for use in this way. The polymer is clearly too expensive to compete with the older materials, and it must be pointed out that the lengthy synthesis of the product rules out the possibility of it ever becoming very much cheaper. Attention has therefore been primarily directed to developing those uses where the polymer's special properties can be used to advantage as a bonus over its more normal properties as a water-soluble film former and binder.

206 JOURNAL OF THE SOCIETY CF COSMETIC CHEMISTS (b) Hair Preparations (i) Hair Lacquers and Wave Sets The first cosmetic products based on polyvinylpyrrolidone to reach large- scale commercial production in the U.S.A. and Europe have been hair lacquers, wav• sets and other allied hair sprays.' It has been stated 8 that in the U.S.A. in 1955 somewhere between thirty-five and thirty-eight million aerosol cans of polyvinylpyrrolidone-based hair spray were sold, and at the time this information was published it was claimed that sales were still increasing rapidly. These sales, in fact, accounted for something in the region of 70 per cent of the total U.S. output of hair sprays in that year. Hair lacquers have, of course, been known for many years, but the older type materials were usually based on shellac and other resins, and in the •*' ..-.•.: •.' •- ::•. •:.-'•?•.-•:•-.-,g• .. *: -•:-• ..• .... :::•. :•'• . •: • ::•'- .--••.•:• •'- -:-:-:':. ':: • "::.• • ." .:? :':...f'e•: •':" .::. :• ? . ....... . .... •.... :..•..:...:• :.%... •..:..-• ..• :.. ( -.. • ...................... ?... .., .,...::.....- :• ,.. • .... ....?:- :• ...... :: •':•:.•t'-":..- '..' •.I'•.•'-'..'. '•, • ........ .•:'•' ..... "' ...... ..&? •. ..... • .... . •.. . ,: :....:-.:"• ,.. .--...:::. •' ...: ...-,......-.-,•....,......:.--,.: ,.: ß :z ....... -. •..' .. •-. ..:. •? :•:.•..•".. ....... * ."* :•.--....:...:.:.:...:'.-- .½• ...¾ : *-* ::'•'•"•.' •. ':* : * '•*•*•":"*' '-*..':2' :?:"':: .* ...... ..' '*' * ::-. ..... •,, ... •.:-...-..?-•,.: ..? .. ,. •. .:..:. .... ..............-. ß .•. --. . ..... . •...•-.• •.... I--.,. ... . .:. . ,.: •,-... :. ...•',• .:.::. :::..:- ':'-'- .:-.... -•...•....:. ... x ..:. •.*m ,:..•:' ß: .& •.., .: ',?:, ".----, .......... ..... ....:..:? ...::.•::..:....: •,.. •½ :1:• '...:'"'"'.::,.:' • ,•., •. :•' '.,::.:?:•?...• .-:....: ,:,: ::?.': •: •, '. .: i• • ' '... ::::::::::::::::::::::::::::1....::'""••-:•{•,:%?'%}2:::?...'*• .. .... .. ....... ..... ..•} :-'..•. .... .. 2 ....... :':" ":".•'-•-- .:') ,-: '*..'-.... .,:... .. ' ::•'.: ::.. ...::..• ,,...... ....:? ..... ....... .:.:.:. ., : ,¾• • .,½::' ,..': .-' . )..?r..:... . :•:.:. Fig. I0o Another view of the spray dryer f•r the final recovery of solid polyvinylpyrrolidone.