SILICONES 75
Figure 2 80
70 60 50 40 30 20 15 17 19 21 23 25 “x” Value 27 29 31 33
Table 3: Melting Range of Structured Gels 5% ADM “x” Value
M.P. (ºC) 53 ~ 60
% Alkyl 47 ~ 50
Melt point 40 ~ 46
* M.P. range was tested by Fisher – Johns melting Point Apparatus
US 7,875,263 teaches: “…that structured gels made with lower
percentages of alkyl dimethicone (1-5% by weight) are soft gels. They liquefy upon the touch and spread rapidly on the skin. At ranges of between 5 and 10% by weight added alkyl dimethicone, the structured gels become increasingly more rigid but still yield under pressure. The cushion of the formulation is increased. “The intermediate level of between 5 and 10% by weight have short play times, spreading out rapidly. At levels of between 10 and 20% by weight the gel becomes very rigid, and the play time is extended. This allows the formulation of products that have wide cosmetic applications, allowing the formulator wide latitude to develop a product that meets consumer expectations. “The higher the number of carbon atoms in the alkyl dimethicone, the higher the melting point of the structured gel. At the melt point the structured gel dissolves making a liquid, upon cooling the structured gel reforms, making the technology very flexible”. The gel can be warmed and melted as often as desired.
Organic oil The aesthetics of the organic oil added to
the product is a major factor in determining the type of gel that is produced. Very dry, low viscosity esters are recommended for antiperspirants, and sun care products higher viscosity esters are recommended for skin care and pigmented products.
Gel evaluations
The evaluations of structured gels were conducted using a C8-10 triglyceride (a common relatively inexpensive triglyceride) and the alkyl dimethicone polymers shown in Table 1. Table 2 shows the composition of the
structured gels prepared using 5% by weight of the ADM materials and 95% by weight.
The melting range of the structured gels made with the formulations in Table 2 are shown in Table 3. Figure 3 shows the melting range used instead on melting point for the blends. The melting starts at 53ºC and was not complete until 60ºC. The percentage of ADM was increased in a subsequent set of experiments to observe the effect upon melt point and structured gel appearance. The finished structured gels have a melting range not a single melt point. Table 4 shows the melt point range at 10% and 20% for each
ADM prepared. One can see that increasing the usage level of ADM did not change the melting range. The texture evaluation of the structured gels is shown in Table 5 and pictures are shown in Figure 4. The hardness of each structured gel made varies proportionally with the % by weight of the alkyl in the ADM. ADM is substantially harder (more brittle) than the other two, which are very similar in hardness.
Emulsions
It is well understood that one way to increase the stability of an emulsion is to provide structure to the two phases. The effect of adding 5% of the ADM to olive oil before making the emulsion was studied. The simple formulation is shown in Table 6. Figure 5 shows the results of the emulsion after 24 hours. Clearly, structuring the oil phase improved the stability. In order to make the structured emulsion the emulsification process needs to be run above the melting point of the ADM chosen. The ADM in the oil phase increases slip and provides a less sticky feel to the formulation.
C8-C10 Triglyceride (95%)
Total (100%)
Table 1: Alkyl Dimethicone polymers evaluated “x” Value 25 25 25
% Alkyl
ADM-1 ADM-2 ADM-3
Table 2: Formulation for Strucured Gels Ingredients
C8-C10 100%
79 60 60
Product A Product B (5%) ADM-1 (5%) ADM-2 C8-C10
Triglyceride (95%)
Triglyceride (95%)
100%
Melt point 58°C 54°C 51°C
Product C
(5%) ADM-3 C8-C10
Triglyceride (95%)
100%
Figure 3: Melting range of Structured Gels 5% ADM. November 2018 PERSONAL CARE EUROPE
Alkyl Dimethicone Melting point (ºC) vs. “x” Value
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