Natural polymer for modern colour applications

Inolex has created and introduces LipFeel Natural, a new, patented polymer suitable for many colour cosmetic applications, particularly lip products. LipFeel Natural is completely derived from renewable and sustainable plant sources, and is produced using green chemistry principles. In this article, Inolex shows the results of various testing to demonstrate how LipFeel Natural can confer many of the benefits sought in modern colour cosmetic applications.

Historically, castor oil has been a key oil component used in many pigmented cosmetic systems. Castor oil is a triglyceride whose alkyl chains are mainly comprised of ricinoleic acid. Ricinoleic acid (chemical name 12-hydroxy-9-cisoctadecenoic) is a monounsaturated fatty acid that has an hydroxyl group in the nine position. The presence of this hydroxyl functionality gives the oil unique properties. Since the hydroxyl group is polar and can hydrogen bond with water, castor oil can confer hygroscopicity and moisturisation to the skin. Additionally, the hydroxyl groups make individual molecules ‘stick together’ through dipole-dipole interactions which in turn increases the viscosity of the oil. The high viscosity can provide skin lubrication benefits, and can make the skin surface appear smoother resulting in higher gloss. Also, higher viscosity assists in suspending pigments. Lastly, the hydroxyl functionality plays a key role in the dispersion and wetting of pigments.

Castor oil does have some drawbacks however. Since it is an unsaturated compound, it is susceptible to oxidative attack which begins as soon as it is refined and packaged for storage. This can lead to rancidity that can cause deleterious effects such as change in colour and taste, and the formation of malodorous compounds and polymeric residues. This has led chemists over the years to create synthetic materials that can mimic the performance properties of castor oil. But, despite its drawbacks, castor oil continues to be the predominantly used oil compound in colour cosmetics, and remains the benchmark to which all new alternatives are compared.