Rheology modifiers for the stabilization of perfume capsules in consumer goods

  1. Susana Fernández Prieto
Supervised by:
  1. José María Franco Gómez Director
  2. Inmaculada Martínez García Director

Defence university: Universidad de Huelva

Fecha de defensa: 08 February 2022


Type: Thesis


This thesis studies different commercial approaches on how to efficiently stabilize perfume capsules to delight consumers in diverse laundry products by using rheology modifiers. However, since laundry products are commodities, cost is extremely important. Therefore, the focus is not only to identify good suspension agents, but also whether those materials have additional benefits that can justify their presence in the formulation and therefore the increase in cost. For this reason, two main venues have been explored: on the one hand, hydrogenated castor oil, which is already used in consumer goods nowadays; on the other hand, microfibrillated cellulose, due to its natural source, not only extremely important for consumers, but also from a sustainability point of view. It was demonstrated that it is possible to improve hydrogenated castor oil suspension efficiency and reduce formula space required by crystallizing it in specific shapes and leveraging hydrogenated castor oil synergies with acids and thickeners. However, given that hydrogenated castor oil has a really low industrial cost, the addition of thickeners or acids is increasing the price of the rheology system. In order to justify the price, additional benefits were identified, like translucent aesthetics and less yellowing. Microfibrillated cellulose has been studied as an alternative to overcome hydrogenated castor oil challenges. While grades for the different applications have diverse requirements, the viscosity build and suspension power are common rheology properties desired in all applications. In a first stage, diverse suppliers have been screened in order to determine the efficiency of the microfibrillated cellulose they offer in consumer goods containing mainly surfactants. During the screening, efficiency and cost were taken into account in order to assess their industrial feasibility, identifying the best source for Fabric & Home Care applications. Then, its performance in diverse formulations, such as fabric enhancers and laundry detergents, was assessed to understand positive and negative interactions with formula ingredients. However, given there is still a significant cost increase versus current systems, also additional benefits were explored in order to justify the cost increase. Among these benefits, deposition of capsules, dispensing residues and hang-up improvements were identified. Overall, it has been demonstrated that both rheology systems, hydrogenated castor oil and microfibrillated cellulose, are suitable for diverse Fabric & Home Care formulations. They provide viscosity increase and successfully physically stabilize perfume capsules.