Microcapsule Shell Formation via Silane Mediator
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Solution Overview
Problem
Existing microencapsulation methods face challenges in reducing latex particle formation and achieving effective capsule shell formation, particularly when encapsulating fragrances, which are complex in chemical nature, leading to issues like fragrance leakage and instability across varying pH conditions in household and personal care products.
Innovation Solution
A microcapsule comprising a perfume composition enclosed within a polymeric shell, utilizing a blend of monoethylenically and polyethylenically unsaturated monomers and a silane compound, with a polymeric shell having a specific composition and size range, to minimize latex particle formation and ensure pH-independent shell properties, thereby reducing fragrance leakage and maintaining homogeneity and viscosity during suspension free-radical polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If suspension free radical polymerization is used to form microcapsule shells, then capsule shell formation is achieved, but latex particles are formed as unwanted byproducts
Solution Approach 1:
A silane compound is introduced as an intermediary substance that selectively interacts with the emulsion droplet surface to promote polymerization at the interface while preventing homogeneous polymerization in the continuous phase. The silane compound acts as a mediator between the monomers and the emulsion droplets, directing polymer chain growth to form shells rather than free-floating latex particles
Solution Approach 2:
The patent modifies the chemical parameters of the polymerization system by introducing the silane compound, which changes the reactivity and distribution of polymerization. This parameter change shifts the polymerization from occurring throughout the continuous phase (forming latex) to occurring specifically at the emulsion droplet interface (forming shells), thereby reducing unwanted latex particle formation
2Loss of substance
If a polymeric shell is formed to encapsulate fragrance, then fragrance leakage is reduced, but shell stability varies under different pH conditions
Solution Approach 1:
The patent creates a composite polymeric shell system incorporating multiple monomer types (ethyleneically unsaturated and polyethylenically unsaturated monomers) along with silane compounds. This composite structure combines materials with complementary properties: some components provide barrier function to prevent fragrance leakage, while others provide pH buffering or structural adaptability to maintain stability across varying pH conditions
Solution Approach 2:
The polymeric shell is designed with heterogeneous composition where different regions or phases of the shell have specialized functions. The shell contains both fragrance-barrier components and pH-stability components in specific distributions, creating local quality variations that collectively provide both leakage prevention and pH-independent stability
3Quantity of substance
If emulsion droplets are encapsulated into polymeric shells, then fragrance encapsulation is achieved, but homogeneity and viscosity of the dispersion change during polymerization
Solution Approach 1:
The silane compound serves as a mediator that controls the polymerization kinetics and polymer chain growth patterns. By directing polymerization to occur at the emulsion droplet interface rather than in the bulk continuous phase, the silane prevents excessive polymer formation that would increase viscosity and cause aggregation, thereby maintaining dispersion homogeneity throughout the encapsulation process
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 solution effectively encapsulates fragrances with reduced leakage, maintains shell integrity across acidic to alkaline pH conditions, and minimizes latex particle formation, making it suitable for use in non-edible consumer goods, laundry, personal care, and cosmetic products.
Implementation Method 1
Microencapsulation through free radical polymerization entails the preliminary formation of an emulsion wherein a continuous, typically aqueous-based, phase disperses an internal, hydrophobic phase to be encapsulated
Implementation Method 2
the polymeric shell further includes in polymerized form a blend including: i) between 20% and 75% by weight over the combined weight of compounds (I) to (III) in the blend of a compound (I) which is a monoethylenically unsaturated monomer and/or dimethyldiallyl ammonium chloride (DMDAAC), ii) between 20% and 70% by weight over the combined weight of compounds (I) to (III) in the blend of a compound (II) which is a polyethylenically unsaturated monomer selected from the group consisting of a C2-C24 alkyl di- or polyester of (meth)acrylic acid, a C2-C24 alkyl di- or polyamide of (meth)acrylic acid and mixtures thereof, and iii) between 0.01% and 10% by weight over the combined weight of compounds (I) to (III) in the blend of a compound (III) which is a silane compound
Data Source
AI summary
A novel microcapsule which is endowed for example with reduced leakage of encapsulated materials. The microcapsule contains one or more fragrances and is suitable for inclusion in non-edible consumer goods products, laundry products, personal care products and cosmetic products. The microcapsule can be obtained in an economic and efficient manner by polymerizing an emulsion so that emulsion droplets are encapsulated into a subsequently cured polymeric shell.