Chitosan-Polyurea Microcapsule Leakage Resistance

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Solution Overview

Problem

Existing microcapsules used in consumer products, particularly those containing perfume ingredients, face challenges with leakage when suspended in extractive media like surfactant-containing detergents and shampoos, leading to instability and loss of controlled release effectiveness.

Innovation Solution

The use of chitosan as a polyamine co-reactant with polyisocyanates and poly(ethylenimine) to form polyurea core-shell microcapsules, which are more impervious and stable, even in high-extractive media, by adding chitosan in solid form under alkaline conditions during the microcapsule formation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polyurea microcapsules are used to encapsulate perfume ingredients, then encapsulation is achieved, but leakage occurs during storage in extractive media such as surfactant-containing detergents and shampoos

Engineering Contradiction:

Improveencapsulation stabilityVSAvoidperfume leakage

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The invention changes the chemical composition parameters of the microcapsule shell by incorporating chitosan and poly(ethylenimine) alongside polyisocyanates. This compositional modification creates a shell with enhanced resistance to extractive media, preventing perfume leakage while maintaining encapsulation functionality during storage in surfactant-containing products.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite shell material comprising multiple components: polyisocyanates, chitosan, and poly(ethylenimine). This composite structure combines the encapsulation properties of polyurea with the stability and resistance properties of chitosan and poly(ethylenimine), creating a shell that resists leakage in extractive media while maintaining encapsulation integrity.

Inventive Principle:

Principle #40Composite materials

2Reliability

If aminoplast thermosetting resins are used to form microcapsule shells, then leakage resistance is improved, but formaldehyde contamination is introduced

Engineering Contradiction:

Improveleakage resistanceVSAvoidformaldehyde presence

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention extracts and removes the harmful formaldehyde component from the aminoplast resin system while retaining the beneficial leakage resistance properties. By substituting chitosan and poly(ethylenimine) for formaldehyde-based aminoplast resins, the invention achieves comparable or superior encapsulation stability without introducing formaldehyde contamination into the final product.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the formaldehyde-based aminoplast resin system with an alternative polyurea system using chitosan and poly(ethylenimine). This substitution eliminates the need for harmful formaldehyde while maintaining the desired leakage resistance, creating a safer encapsulation solution suitable for consumer products.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If aromatic polyisocyanates are used to form polyurea resin, then microcapsule formation is achieved, but oxidation resistance is reduced

Engineering Contradiction:

Improvemicrocapsule formationVSAvoidoxidation resistance

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The invention changes the chemical structure parameter of the polyisocyanate component from aromatic to aliphatic. Aliphatic polyisocyanates provide the necessary microcapsule formation capabilities while offering superior oxidation resistance compared to aromatic variants, thereby improving the long-term stability of the encapsulated perfume composition.

Inventive Principle:

Principle #35Parameter changes

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 exhibit enhanced retention of encapsulated ingredients, maintaining over 80% stability of perfume compositions during storage in extractive bases like shampoos and detergents, with reduced leakage and preserved olfactive notes, outperforming conventional polyurea microcapsules.

Implementation Method 1

a shell comprising a polyurea resin formed by the reaction of at least one polyisocyanate, chitosan, and at least one polyimine

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

Microcapsules can isolate and protect the functional ingredients from external suspending media

Methodology Applied

Scientific EffectPhysical Containment: Physical Containment

Implementation Method 3

decrease the permeability of microcapsule shells

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentEP3687678B1Improvements in or relating to organic compounds

Publication Date: 2023.05.24 GIVAUDAN SA

AI summary

Core-shell microcapsules comprising a hydrophobic core surrounded by a shell comprising a thermosetting resin comprising moieties derived from polyisocyanates, substantially unprotonated chitosan and another amine different from chitosan, characterized in that the substantially unprotonated chitosan is delivered in the solid, powder form to the locus of the encapsulation reaction. The core-shell microcapsules are provided in the form of a slurry comprising 10 to 50 wt% of microcapsules, based on the total weight of the slurry, and the shell of the microcapsules comprises from 0.1 to 20 wt % of moieties derived from chitosan, based on the total weight of the shell.