J. Soc. Cosmet. Chem., 22, 655-666 (September 17, 1971) Encapsulated Perfumes in Aerosol Products JEFFREY M. MILES, B.A., BERNARD M. MITZNER, M.S., JOSEPH BRENNER, Ph.D., and ERNEST H. POLAK, M.S.* Presented May 26-27, 1970, New Yorh City Synopsis--Stable, spray-dried, ENCAPSULATED FRAGRANCES which are formulated in AEROSOLS are described. When sprayed on a surface, under both in vivo and in vitro conditions, these gradually release fragrance upon exposure to moisture. It is shown that RELEASE RATE can be varied according to the liquid vchicle and that it varies with the individual test subject and the stimuli to which he is exposed. A novel analytical technique has been developed that simultaneously monitors the vola- tiles relcascd from an encapsulated fragrance and the moisture content of the axillary region of the subject. INTRODUCTION Liquid fragrances used in aerosol products tend to behave in the same manner as topically applied perfumes. The odor of the more vola- tile perfume components is noticed first, that of the moderately volatile components next, and at the end of a period of time only the odor of the least volatile ones. This effect is characterized in Fig. 1 by the bolder curves. Both the strength and character of a liquid fragrance change within a time period. Ideally, freshness of top note and unfading odor strength should be maintained throughout the application life. Fulfillment of such a requirement is not possible at present with liquid perfume oils. However, if the release of perfume volatiles could be delayed by a suitable encapsulation until functionally needed, greater fragrance inte•ity and * Polak's Frutal Works, Inc., 33 Sprague Ave., Middletown, N.Y. 10940. 655

656 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS lO 9 8 7 •.6 Ld 5 LO 4 3 1 TOP NOTE IllIll IDEAL IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII BODy CONVENTIONAL DRY OUT 1 2 3 4 5 6 7 8 TIME Figure 1. Comparison of ideal perfume behavior with actual effect more uniform strength could be provided, which would approach the ideal shown in Fig. 1. Highly water-soluble encapsulations of perfume oil are one approach to producing a delayed and periodic fragrance re- lease in a properly formulated aerosol product (1). Spray drying is one approach to producing such an encapsulation (2). By this method, free-flowing powders with up to 50% perfume oil in a highly water-soluble shell have been produced utilizing our technology. The encapsulations may be typified as dried, particulate, miceilar structures containing perfume oils. Since the encapsulation particles consist of one or more dried micelies, the finished powder has a particle size distribution which reflects this characteristic. Table I shows the particle size distribution of one such product, (• -CAP%* EXPERIMENTAL Initial small-scale, valve clogging studies were undertaken to deter- mine physical compatibility with aerosol systems. These were supple- mented by large-scale tests* in an aerosol, dry antiperspirant formulation. These tests indicate a cloggage level that is not greater than the controls. * •-CAP is a registered trademark for water-soluble, encapsulated per*runes manu- factured by Polak's Frutal Works, Inc., Middletown, N.Y. ? Carried out in cooperation with Aerosol Techniques, Inc., Milford, Conn.