Comparison of Smectite Clays in Underarm Products - Elementis ...

More documents

Recommendations

Info

Introduction The functionality of smectite clays (primarily Hectorite or Bentonite in origin) as rheology modifiers and especially as suspension aids for Aluminium salts, which are the active ingredients in antiperspirants, is well appreciated. Even a casual review of ingredient labels on store shelves will reveal their usage in most aerosol and roll-on antiperspirant products. They are also used in antiperspirant sticks as an in-process suspension aid, so that the Aluminium salts do not settle out while the sticks are still in their molten state before the fatty alcohols have an opportunity to solidify during cool-down. Once the stick has formed they provide an internal matrix that enhances structural integrity, smooths application, controls payout rate and provides a soft skin feel. Request a copy of our 'Antiperspirants Formulary' for examples of a wide range of underarm antiperspirant prototypes that have been stability tested. A comparison of the fundamental properties of Hectorite are an indication of its key performance advantages over Bentonite. Hectorite offers the general benefits of higher rheological efficacy (viscosity and yield value), lower iron content and lighter colour (1) . In addition, test results presented in this brochure will show that Hectorite clay and organoclays offer benefits specifically for antiperspirant/deodorants, including anti-settling of actives and significantly less staining potential of cotton fabrics than Bentonites, due to contact with low pH Aluminium salts. Thus the usage of Hectorite reduces the objectionable and unsightly appearance of dark yellow armpit staining of shirts. The use of Bentonite is more likely to require EDTA and other chelating agents to sequester its higher iron content. The phenomenon of armpit staining of white cotton shirts and undergarments associated with Aluminium salts is likely only to be enhanced in-vivo with the presence of sweat and sebaceous secretions. Using products containing the INCI names of either ''Hectorite'' and/or ''Disteardimonium Hectorite'' on the ingredient labels is a consumers best assurance that the level of staining potential due to the presence of Aluminium salts is at a minimum. 1
What are Smectite Clays? Smectite clays belong to a family of layered minerals that are comprised of individual platelets with a metal oxide center sandwiched between two Silicone Dioxide outer layers. Included in this group of minerals are Hectorite, Bentonite (Montmorillonite), Saponite, Sepiolite, Beidellite, Nontronite and Sauconite. Of these, Hectorite and Bentonite are the most important because of their swelling properties and availability. Because of the structure these clays build after they swell in water, they have become commercially important as rheological additives, or flow control agents. In the cosmetics industry, clay based products are used to improve properties such as suspension, emulsion stability, viscosity, thermal stability and spreadability. Structurally, Bentonite is a dioctahedral, Aluminium based clay, while Hectorite is a trioctahedral, Magnesium based clay. This structural difference leads to differences in the chemistry and physical properties of the two clays. In addition, Hectorite does not contain any crystalline Silica. Both Bentonite and Hectorite clays can be reacted with organic compounds to form organophilic clays. These swell in anhydrous media and maintain the same physical properties of the reacted hydrophilic bases; i.e., Hectorite based organoclays have a lighter colour, lower iron content and greater viscosity efficiency. In Table 1 we can see the general properties of Hectorite and Bentonite. Hectorite Bentonite Chemistry Na 0.33 [Mg 2.67 Li 0.33 ]Si 4 O 10 [OH] 2 Na 0.33 [Al 1.67 Mg 0.33 ]Si 4 O 10 [OH] 2 Platelet Shape Elongated Equidimensional Platelet Size (dispersed) 0.8 x 0.08 x 0.001 microns 0.8 x 0.8 x 0.001 microns Type Trioctahedral Dioctahedral Swelling Ability 35 x 15 x Colour Light Pink to Tan Grey to Green Iron (typical) 0.2% 2.3% Viscosity (5% concentration) Table 1. Typical properties of Hectorite and Bentonite 10000 mPa.s 750 mPa.s 2
Page 4 and 5: Morphology of Hectorite and Bentoni
Page 6 and 7: Viscosity Pa.s Viscosity and Yield
Page 8 and 9: Suspension of Particles in Antipers
Page 10 and 11: Low Staining Potential of Hectorite
Page 12 and 13: ∆E CIE L*a*b* Measurements of Hec
Page 14 and 15: ∆E CIE L*a*b* Measurements of Cla
Page 16: References: 1. Clarke, M. T., in 'R

Comparison of Smectite Clays in Underarm Products - Elementis ...

Create successful ePaper yourself

Delete template?

Save as template?