Aqueous microcapsule dispersion

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Solution Overview

Problem

Aqueous microcapsule dispersion liquids face issues with dispersion stability, particle diameter uniformity, and fluidity due to differences in specific gravity and physical or chemical changes, leading to creaming, sedimentation, gelation, and aggregate formation, which existing methods inadequately address.

Innovation Solution

Incorporating microcapsules with an inorganic shell and an organic core, along with a polysaccharide having a cationically modified branched chain structure, to enhance dispersion stability, achieve uniform particle diameters, and prevent aggregate formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If microcapsules are dispersed in aqueous medium, then the dispersion liquid can be used directly without isolation operations, but the microcapsules undergo creaming or sedimentation due to specific gravity differences, losing fluidity

Engineering Contradiction:
Improvedirect use without isolation operationsVSAvoidfluidity
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

A surfactant is introduced as an intermediary substance between the microcapsules and aqueous medium. The surfactant reduces interfacial tension and prevents aggregation, allowing the dispersion liquid to be used directly without isolation operations while maintaining fluidity and stability against creaming or sedimentation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The dispersion liquid is formulated as a composite system containing microcapsules, surfactant, and aqueous medium. This composite structure leverages the surfactant's amphiphilic properties to stabilize the dispersion, enabling direct use without isolation while preventing phase separation and maintaining fluidity.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If microcapsules are dispersed in aqueous medium, then the dispersion liquid can be used directly without isolation operations, but aggregates form due to physical or chemical changes, losing fluidity

Engineering Contradiction:
Improvedirect use without isolation operationsVSAvoidaggregate formation
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The surfactant acts as a protective intermediary that adsorbs onto microcapsule surfaces, preventing direct interactions that lead to aggregation. This intermediary layer stabilizes the dispersion physically and chemically, allowing direct use without isolation operations while preventing aggregate formation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful aggregation tendency is extracted and counteracted by introducing the surfactant. The surfactant specifically targets and prevents the aggregation mechanism, separating the stabilizing function from the microcapsules themselves and allowing the dispersion to remain stable and fluid without isolation operations.

Inventive Principle:
Principle #2Taking out (Extraction)

3Stability of the object's composition

If viscosity modifiers are used to enhance dispersion stability, then the dispersion stability is improved, but the fluidity and handleability deteriorate

Engineering Contradiction:
Improvedispersion stabilityVSAvoidfluidity
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

Instead of changing viscosity parameters, the invention changes the surface chemical parameters of microcapsules by introducing surfactant. This parameter change stabilizes the dispersion through electrostatic or steric repulsion mechanisms without increasing viscosity, maintaining both dispersion stability and fluidity for easy handling.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The mechanical approach of using viscosity modifiers to stabilize dispersion is replaced with a chemical/electrostatic approach using surfactant. This substitution achieves stabilization through molecular-level interactions rather than bulk viscosity increase, preserving fluidity and handleability while improving dispersion stability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 provides an aqueous microcapsule dispersion liquid with improved stability, uniform particle diameters, and maintained fluidity even after long-term storage, effectively suppressing aggregate formation and enhancing handleability.

Implementation Method 1

a polysaccharide including a cationically modified branched chain structure

Methodology Applied
Scientific EffectElectrostatic repulsion: Ion Repulsion/Attraction

Data Source

PatentUS20240293295A1Aqueous microcapsule dispersion
Publication Date: 2024.09.05 KAO CORP

AI summary

An aqueous microcapsule dispersion liquid containing a component (A) and a component (B), component (A): microcapsules having a shell comprising an inorganic material as a constitutional component, and a core including one or more of an organic compound, inside the shell, and component (B): a polysaccharide containing a cationically modified branched chain structure. A content of the component (B) per 100 parts by mass of the component (A) in the aqueous microcapsule dispersion liquid is 0.03 part by mass or more and 3 parts by mass or less.