TEXTURES 79
18 16 14 12 10 8 6 4 2 0
0 2 4 6 Time (min) micro-porosity
n Sodium Cocoyl Glutamate (Perlastan SC 25 NKW) n Sodium Lauroyl Sarcosinate (Perlastan L-30) n Cocamidopropyl Betaine (CAPB) n Sodium Lauryl Sulphate n Sodium Laureth-3 Sulphate n Sodium Oleate
++ ++ + + –
––
Figure 6: Ross-Miles test with sodium cocoyl glutamate (Perlastan SC 25 NKW), sodium lauroyl sarcosinate (Perlastan L-30) and other surfactants (active content of 3 g/l).
surfactants such as sodium cocoyl glutamate (CMC 0.4 g/l), sodium lauroyl glutamate (CMC 0.4 g/l) or sodium lauroyl sarcosinate (CMC 0.4 g/l) can reduce the irritant effects and produce a milder formulation. They may be added at very low levels for instance to SLES and amphoteric surfactants (betaines) formulations to produce significantly milder effects with positive influence on the health of the skin’s surface. The protective monolayer reduces adsorption of aggressive surfactants on the skin and at the same time loss of skin moisture is prevented.7
When the surfactants are mixed with non-ionic surfactant coco glucoside (CMC 0.045 g/l) in equivalent ratio, the total-CMC is reduced from 0.4 g/l to 0.12g/l or 0.2 g/l (Fig 3). This means that a lower concentration of surfactant is needed to obtain same cleansing performance with excellent foam ability and mildness of the product.
Formulation A INCI Aqua
Sodium Cocoyl Glutamate / Disodium Cocoyl Glutamate Sodium Lauroyl Sarcosinate Sodium Laureth Sulphate Cocamidopropyl Betaine Ammonium Chloride Citric Acid
Preservatives, Fragrances, etc.
Figure 7: Foam stability: Time-dependent drainage amount of sodium cocoyl glutamate (Perlastan SC 25 NKW), sodium cocoyl glutamate/coco glucoside/xanthan gum, sodium lauroyl sarcosinate (Perlastan L-30) and other surfactants (active content of 3 g/l).
Dynamic processes Determination of the CMC allows a good insight into static processes of a surfactant when a thermodynamic equilibrium has been established. Since soaping in the shower is an active process, it is obvious to have a closer look at this as a dynamic process. For this purpose coco glucoside, sodium cocoyl glutamate (SC 25 NKW) and sodium lauroyl sarcosinate (L-30) were subjected to measurements of dynamic surface tension (SFT). The solutions were prepared with an active content of 1 g/l of surfactant, which corresponds to a concentration higher than the CMC of these surfactants. The dynamic process was investigated using a bubble pressure tensiometer (Krüss) applying the method of maximum bubble pressure on freshly generated surfaces (surface age: 14 to 10000 ms).8
The diffusion of surfactant
molecules plays an important role. The faster the movement to the newly formed surface occurs, the faster the surface
% 15.00
26.70 6.30
32.75 13.75
5.00-7.00
qs to pH 5.5 qs
‘Green’ Formulation B INCI Aqua
Cellulose Gum (and) Carrageenan (and) Ceratonia Siliqua Gum (and) Sucrose
Coco Glucoside
Sodium Cocoyl Glutamate / Disodium Cocoyl Glutamate Glycerin
Glycerinmonooleate Citric Acid or Lactic Acid Preservatives, Fragrances, etc. 8 10
100 90 80 70 60 50 40 30 20 10 0
0 5 10 15 Drainage Time (min)
n Coco Glucoside n Cocamidopropy Betaine n Sodium Laureth Sulfate n Sodium Lauryl Sulfate n Sodium Lauroyl Sarcosinate PERLASTAN L-30 n Sodium Cocoyl Glutamate PERLASTAN SC 25 NKW n Sodium Cocoyl Glutamate PERLASTAN SC 25 NKW/Coco Glucoside (1:1)+Xanthan Gum (0.75%)
20 25
Foam height
Liquid height
Figure 8: Measuring principle of the Dynamic Foam Analyser DFA100 (Krüss).10
tension of the solution decreases as a function of surface age.
Thus, the steeper the measuring curve
falls off, the more effective the surfactant is. As reference, water was used with a constant surface tension of 73 mN/m. Figure 4 shows the time-dependent
% 65.90 1.00
10.00 17.50 5.00 0.60
qs to pH 5.5 qs
Figure 9: Formulation A and B with sodium cocoyl glutamate (Perlastan SC 25 NKW) and sodium lauroyl sarcosinate (Perlastan L-30). September 2018
PERSONAL CARE EUROPE
Foam Height (cm)
Ratio (Draining Amount/Foam Weight) (%)
LED Panel
Photon Detector
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