242 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS TABLE 5B--CoMPARISON OF COMPATIBILITY OF SILICONE ESTERS AND 200 A•r 555 FLUmS WITH VARIOUS MATERIALS* Dow Corning Octyl Lauryl Stearyl Behenyl 555 Fluid 200 Fluid Me•.$jO Confenf Low hi law hi law hi low hi 350 cs Stearyl alcohol C C C C C C C C C i [sopropyl myr[state G i C i C C C i C C Glyccryl monastearate C C C C C C C C C i Diglycol stearate C C C C C C C C C i OIclc acid C C C C C C C C C • Stearic acid C C C C C C C C C i 200 Fluid, 100 cs C C i i i i i i C C 555 Fluid C C C C C C C C C i Tested at room temperature os o m•x made up of ] part sdlcone to I0 ports material listed C compat,ble , ,ncompat•ble For example, the behenyl esters are harder than the stearyl esters. How- ever, as the silicone portion increases, the waxes become softer. The waxes, like the fluids of this ester series, spread easily. Again you will note that these products, as do the salicylate ended fluids, represent a compromise between silicone characteristics and properties associated with organic chemicals. The compatibility of the fatty alcohol esters is compared with 350 cs. Dow Corning 200 Fluid and Dow Corning 555 Fluid in Table 5. In general, these esters are soluble in 95 per cent ethanol 99 per cent iso- propanol animal fats and waxes esters such as isopropyl myristate and glyceryl monostearate fatty acids hydrocarbon oils and waxes vegetable oils, and silicone oils. They are insoluble in water, 70 per cent isopropanol, glycols and glycerine. Obviously, the compatibility characteristics of these esters closely resemble those of Dow Corning 555 Fluid. Water repellency of the wax-like esters as measured by contact angle, is about the same as paraffin. Panels were coated with the various waxes and discrete water droplets placed on each panel. Visual estimation of contact angle showed that the behenyl alcohol esters are equivalent to paraffin. The stearyl alcohol esters, although exhibiting water repellency, have a somewhat lower contact angle. The fluid esters were not checked specifi- cally for contact angle, but because of their incompatibility with water, it is thought that they too possess a degree of water repellency. Since water does not wet these esters readily, they will be especially resistant to hydrolysis.

NEW SILICONES FOR THE COSMETIC INDUSTRY 243 OCTYL ESTER lOO low Me•SiO content high Me•SiO content Cell = Standard -- Path Length = I cm / Reference • Air / / ,' / / ! - / / 8O 60 4o 20 240 280 320 360 400 420 LAURYL ESTER low Me•SiO content .... -- high Me2SiO content .... Cell = Standard ----- Path Length = I cm- Reference = Air // __ ß // // // // //./ : 240 280 320 360 400 420 WAVE LENGTH, millimicrons ß Figure &--Light transmission of fluid silicone esters. STEARYL ESTER BEHENYL ESTER , , low Me•SiO content high Me,SiO content Cell = Sandwich Ponel Path Length = 0.025 mm Reference = Clean Quartz Slide .•' 20 240 280 320 360 400 420 , , , , law MemSiO content -- high MesSiO content .... Cell = Sandwich Panel _ Path Length = 0.025 mm Reference • Clean Quartz Slide I 240 280 320 360 400 420 WAVE LENGTHß mdhm•crons Figure 4.--Light transmission of wax-like silicone esters. Light transmission curves shown in Figs. 3 and 4 indicate that the esters exhibit slight ultraviolet absorption. The fluid esters of octyl and lauryl alcohol transmit very little light at wavelengths less than 320 rn•. Greater absorption is noted where the dimethylsiloxane content is low, while little difference is observed between the octyl and lauryl derivatives. Determinations were made using an empty quartz cell as reference. The wax-like esters were evaluated by preparing a 0.02S-min. pathlength