16 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS lOO 9o 8o 7o 6o 4o 3o 2o lO o • PDMS --•--IPM '--A--MQ ---N--C10MQ • C12MQ '-e--C18MQ ! ! 0 I 2 3 4 5 Spray Cycles Figure 6. Comparison of substantivity on polycarbonate slides for dimethicone, isopropyl myristate, un- modified silicone resin, and siloxysilicate resins modified with ester groups containing 10, 12, and 18 (isostearyl) carbon atoms per chain. completion of the sixth rinse it proved to be equivalent to the C•6 straight-chain compound. The C•2 or the C•8 isostearyl ester-modified siloxysilicates were evaluated in water resistance and SPF studies conducted at an independent laboratory. These materials were applied out of a prototype sunscreen formulation and were compared to a control composition containing an organic ester, octyl palmitate. All three of the formulations were characterized by initial SPF values of 15, as can be seen in Table VIII. The results indicate a slight removal of the formulation containing the C•2 silicone ester after 40-min exposure in water, with the initial SPF 15 value dropping to 13.5. A further decrease in the SFP value to 12 was observed after the subjects were submerged for 80 min. The C•8 ester-modified siloxysilicate and the organic ester were both found to be more substantive than the C• material in this particular formulation. Both the octyl palmirate and C•8 isostearyl ester-modified siloxysilicate demonstrated water resistance properties as evidenced by unchanged SPF values following a 40-min exposure in warm Table VIII SPF Values of Prototype Sunscreen Formulations With Organic or Silicone Esters Time C•2M Q C•8M Q Octyl palmitate 0 15 15 15 40 min 13.5 15 15 80 min 12 13 13

ORGANOFUNCTIONALIZED SILICONE RESINS 17 water. Neither one of these compositions, however, demonstrated "water proof," or "very water resistant" properties from this particular formulation, with the SPF values of both treatments falling to 13 after an 80-min water exposure. Since the isostearyl ester-functional silicone resin demonstrated somewhat substantive film-forming properties in the above experiments, a series of experiments was planned to investigate whether this film could reduce pigment transfer in color cosmetic prod- ucts, particularly lipsticks. Both the C•2 and the C•8 ester resins were evaluated in this study. The lipstick composition used in these evaluations is presented in Formulation 4 listed in Appendix A. Panelists applied each product to one half of their lips, top and bottom of one side. After a 60-sec set time the lips were blotted with tissue and the amount of pigment transfer rated visually. In all cases the amount of pigment visible on the tissue was dramatically lower on the side of the lips to which the C18 composition had been applied. Panelists then reapplied the products and evaluated wear and feath- ering characteristics throughout the day. In all cases, the panelists reported that the side of their lips treated with the composition containing the C18 isostearyl ester-functional resin maintained color longer and did not noticeably feather or bleed to surrounding skin. The C12-functional material did not perform as well in any of the evaluations. Similar results have been reported by other authors in unrelated experiments involving numerous lipstick formulations (17-20,22). CONCLUSIONS It is possible to modify siloxysilicate resins to obtain or enhance various properties desired in cosmetic formulations including skin substantivity, hair body, and shine. Organic modification of siloxysilicate resins is readily accomplished through hydrosi- lylation chemistry, the resulting molecules demonstrating enhanced compatibility with common cosmetic ingredients and thus providing greater formulation flexibility and product stability. It has been shown that ester-modified resins provide some condition- ing benefits to hair while imparting resistance to water wash-off in skin care composi- tions. These particular silicone resin esters are completely non-irritating to the skin and eyes. This property, combined with the excellent film-forming characteristics of siloxy- silicate resins renders the ester-functional materials efficacious in skin care and color cosmetic applications to help reduce pigment transfer and to impart water-resistant characteristics to the formulations. The siloxysilicate resins modified with alkyl moieties of less than ten carbon atoms per chain were found to perform similarly to the unmodified compounds in all evaluations. The resins containing olefin chains of ten or more carbon atoms were found to slightly reduce wet combing forces. Surprisingly, the compounds containing olefin chains of sixteen or more carbon atoms were found to act as volumizing agents in hair care applications, increasing maximum tress diameter by 8 and 20 percent for the C•6_18 and C2o_24-modified materials, respectively. The formulation containing the C•o-modified compound provided a minor increase in tress diameter as compared to the base condi- tioner (-10% versus -12% for the base), but this value was still significantly less than for the untreated hair. While conditioning benefits were found to be independent of alkyl chain length within experimental error, the hair volume or maximum tress diam-