Physical and material properties of an emulsion-based lipstick produced via a continuous process

• Published in: International journal of cosmetic science 2014-04, Vol.36 (2), p.148-158
• Main Authors: Beri, A., Pichot, R., Norton, I. T.
• Format: Article
• Language: English
• Subjects: continuous process; Cosmetics - chemical synthesis; Cosmetics - chemistry; emulsions; Emulsions - chemical synthesis; Emulsions - chemistry; Lipstick; lipsticks; Microscopy, Polarization; Particle Size; Viscosity
• ISSN: 0142-5463; 1468-2494
• DOI: 10.1111/ics.12108

Synopsis Objectives Water‐in‐oil emulsions in lipsticks could have the potential to improve moisturizing properties and deliver hydrophilic molecules to the lips. The aim of this work was to investigate the effect of a continuous process (scraped surface heat exchanger (SSHE) and pin stirrer (PS)) on the physical and material properties of an emulsion‐based lipstick by altering the processing conditions of both the SSHE and PS. Methods Emulsion formation was achieved using a SSHE and PS. Emulsions were analysed using nuclear magnetic resonance restricted diffusion (droplet size), texture analysis and rheology (mechanical properties). Results Results showed that a higher impeller rotational velocity (IRV) (1500 r.p.m.) and a lower exit temperature (52°C) produce the smallest droplets (~ 4 μm), due to greater disruptive forces and a higher viscosity of the continuous phase. The addition of a PS reduces the droplet size (14–6 μm) if the SSHE has a low IRV (500 r.p.m.), due to greater droplet disruption as the emulsion passes through the PS unit. Results also show that if the jacket temperature of a SSHE is 65°C, so that crystallization occurs in both process and post‐production, droplets can be integrated into the network resulting in a stiffer wax network (G' – 0.12, in comparison to 0.02 MPa). This is due to small crystals creating a shell around water droplets which can form connections with the continuous network forming a structured network. The addition of a pin stirrer can disrupt a formed network reducing the stiffness of the emulsion (0.3–0.05 MPa). Conclusion This work suggests the potential use of a continuous process in producing an emulsion‐based lipstick, particularly when wax crystals are produced in the process. Future work should consider the moisturizing or lubricating properties of wax continuous emulsions and the release of hydrophilic compounds from the aqueous phase. Résumé Objectifs Les émulsions eau‐dans‐huile dans les rouges‐à‐lèvres pourraient avoir le potentiel pour améliorer les propriétés hydratantes et délivrer des molécules hydrophiles aux lèvres. L'objectif de ce travail était d'étudier l'effet d'un processus continu (échangeur racleur (SSHE) et Agitateur Pin (PS)) sur les propriétés physiques et matérielles d'un rouge à lèvres à base d'émulsion en modifiant les conditions de traitement à la fois du SSHE et PS. Méthodes La formation d'émulsion a été réalisée en utilisant un SSHE et PS. Les émulsions ont été analysées en utilisa