Crosslinked Microcapsules for Fragrance Stability
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Solution Overview
Problem
Microcapsules used in perfumery and consumer products face instability in high ethanol and surfactant-rich environments, leading to leakage and degradation, which compromises their ability to protect and release fragrance oils effectively.
Innovation Solution
The process involves suspending amine-functionalized inorganic particles and maleic anhydride-containing polymers in water and fragrance oils to form crosslinked microcapsules with a core-shell or matrix structure, providing covalent crosslinking at the oil/water interface, enhancing stability and retention of fragrance oils in challenging bases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aminoplast microcapsules are used to encapsulate hydrophobic actives, then the actives are protected and controlled release is provided, but the capsules suffer from stability problems in surfactant-containing products leading to leakage through diffusion
Solution Approach 1:
The invention uses a composite capsule wall structure comprising both organic polymer matrix and inorganic particles. The inorganic particles (such as silica, alumina, or titania) are incorporated into the polymer matrix to create a hybrid material that combines the protective properties of the polymer with the stability and low surfactant affinity of inorganic particles, thereby preventing active leakage while maintaining controlled release
Solution Approach 2:
The inorganic particles are specifically positioned at the oil/water interface within the capsule wall structure. This localized placement at the interface provides enhanced stability and surfactant resistance precisely where the capsule is most vulnerable to destabilization, while the bulk polymer matrix maintains its protective and controlled release functions
2Adaptability or versatility
If microcapsules are suspended in surfactant-rich consumer products, then fragrance delivery is enabled, but the capsules physically dissociate or degrade over time
Solution Approach 1:
The hybrid organic-inorganic composite material provides enhanced overall capsule integrity. The inorganic particles create a more rigid and stable framework within the polymer matrix, preventing physical dissociation of the capsule structure in challenging surfactant-rich environments while still allowing the capsule to function as intended in various consumer products
Solution Approach 2:
The inorganic particles act as intermediary elements that mediate between the organic polymer matrix and the external surfactant environment. These particles have low affinity for surfactants and provide a stable interface that prevents surfactant-induced destabilization, thereby maintaining capsule integrity in surfactant-rich products
3Adaptability or versatility
If microcapsules are added to fine fragrance formulations with high ethanol content, then fragrance delivery is achieved, but destabilization and dissociation occur through different mechanisms
Solution Approach 1:
The composite capsule wall structure provides enhanced resistance to ethanol-induced destabilization. The inorganic particles create a more rigid and chemically stable framework that is less susceptible to solvent effects, maintaining capsule integrity in high ethanol content formulations where conventional organic-only capsules would dissociate
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting microcapsules demonstrate remarkable stability in surfactant and high ethanol environments, preventing dissociation and degradation, while maintaining effective encapsulation and controlled release of fragrance oils, thus overcoming previous stability issues.
Implementation Method 1
Crosslinking of capsule walls, with chemical groups such as poly(amines) and poly(isocyanates), has been described as a way to improve stability of microcapsules
Implementation Method 2
Stabilization of oil/water interfaces with inorganic particles has been described in so-called Pickering emulsions
Implementation Method 3
the ability of surfactant molecules to readily displace particles from oil/water interface of emulsions
Data Source
Figure 1
Figure 2
Figure 3~4(d)
AI summary
The present invention relates to microcapsules with a core-shell or matrix morphology stabilized by cross-linked nanoparticles. A process for the preparation of said microcapsules comprising selecting internal crosslinking of a Pickering emulsion is also an object of the invention. Perfumed consumer products, in particular fine fragrance, home and personal care products are also part of the invention.