100 TEXTURES
Green chemistry for high impact colour cosmetics
n Lisa Gandolfi PhD – Inolex, US
The rise of social media influencers and the emergence of the Clean Beauty lifestyle have converged, creating a colour cosmetics market that must deliver high impact and sensory stimulating products with ingredients consumers feel are healthy and safe. According to Mintel Group, ingredients
are a top concern for consumers and the demand for clean formulations with proof of results will become the expectation of consumers in the near future.1
Clean
ingredients will help brands gain consumer trust and transparency will be a critical element of that success. In the colour cosmetics market, performance cannot be a trade-off for clean formulations and brands will be required to demonstrate strong proof of results. Following the mega-trend of social media influencers, bold colours and exciting textures will be drivers for new product success.
Polyester ingredients deliver impactful performance Polyesters are an important class of cosmetic ingredients. There are over 200 different types of polyesters listed in the International Cosmetic Ingredient
end group HO X O
O C
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ester bond O
C O repeat unit Figure 1: Polyester general structure.3
Dictionary and Handbook with a variety of functions, including film-forming and conditioning agents for skin and hair.2 Polyesters are polymer chains comprised of repeat units linked by ester bonds as shown in Figure 1. Polyester backbones are polar due to the ester bonds and the degree of polarity is controlled by increasing/decreasing aliphatic content in the backbone and the polymer chain end groups. Generally polyesters are hydrophobic and insoluble in water but can be rendered water-dispersible or water- soluble by incorporating hydrophophilic ionizable groups into the backbone. Polyesters can be linear, branched, and/or
O O O O R O O O R
where RCO = palm acyl group
O O
Figure 2: Primary polyester structure of branched and crosslinked polyesters derived from adipic acid, pentaerythritol, and palm acid.
PERSONAL CARE ASIA PACIFIC O O O O O O O O R O O O O O O O O O O O
crosslinked and the difference in the structure modulates critical physical properties such as viscosity and film formation. The polyester chemical structure can also be varied to modulate compatibility in solution and on surfaces, solubility properties, and dispersion properties. Two polyester molecules will be discussed in this paper. The primary structure of both molecules is shown in Figure 2 and the structure variations are referenced in the respective sections about this polymer. LexFeel™ Vibrant (Palm Acid/Adipic Acid/Pentaerythritol Crosspolymer) is a branched/crosslinked polyester according to Figure 2 with long carbon chain (C16 – C18) end groups. This specific polyester structure results in a stiff and waxy ingredient structure that can cocrystallise with waxes to provide structure and texture in cosmetic formulations. In comparison to using only traditional waxes, such as beeswax and ozokerite, addition of the LexFeel Vibrant polyester maintains structure while controlling negative effects like sweating (Fig 3). Additionally, this polyester is an amorphous and low Tg polymer compared to crystalline waxes which provides thickening of the oil phase without causing haziness or clouding. This results in an improved formulation background for pigments giving a brighter and more vibrant colour in the product and upon application. As can be seen in Figure 4, the result is higher payoff and more brilliant impactful colour upon application – ideal to deliver bold colours on trend with the colour cosmetics market.
November 2019 O n
O C
Y
O C
O X end group OH
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