Elongated Microcapsule Formation via Emulsion Shear

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Solution Overview

Problem

Current methods for producing elongated microcapsules below 200 microns are limited by equipment size and scalability, making them unsuitable for industrial production, especially in coating and composite applications.

Innovation Solution

The formation of elongated microcapsules through an emulsion system by pulse stirring or shearing between two surfaces moving at different velocities, allowing for the creation of microcapsules with a solid shell and a core content that can release corrosion indicators, inhibitors, or self-healing agents in response to corrosion or physical trauma.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If conventional extrusion methods through concentric bores are used to produce elongated capsules, then elongated capsule formation is achieved, but the minimum size is limited to around 200 microns and scale-up requires additional equipment

Engineering Contradiction:

Improvecapsule elongationVSAvoidminimum capsule size

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical extrusion system (concentric bores) with an emulsion-based system where capsules form through phase separation and coalescence. This substitution allows capsules to form at much smaller sizes (below 200 microns) while maintaining elongated shapes, as the emulsion droplets can be controlled at micro-scale through mixing and shear forces rather than being constrained by bore dimensions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the formation mechanism parameters from fixed geometric constraints (bore sizes) to controllable emulsion parameters (droplet size, interfacial tension, coalescence conditions). By adjusting emulsion composition, shear rate, and processing conditions, the capsule size can be precisely controlled below 200 microns while maintaining elongated morphology, overcoming the minimum size limitation of extrusion methods.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If conventional extrusion methods are used for mass production of elongated microcapsules, then production scale-up is possible, but equipment complexity and cost increase significantly

Engineering Contradiction:

Improvemass production capabilityVSAvoidequipment setup

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The emulsion-based system uses standard mixing and processing equipment that can be used for both small-scale laboratory production and large-scale industrial manufacturing. The same basic apparatus (mixers, shear devices, drying equipment) serves all production levels, eliminating the need for specialized extrusion equipment and complex multi-stage systems required by conventional methods.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extracts the capsule formation process from the complex extrusion equipment system and transfers it to a simplified emulsion-based approach. By taking out the formation mechanism from the mechanical extrusion system, the process can be performed using simple mixing and shear devices, dramatically reducing equipment complexity while maintaining mass production capability.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of manufacture

If spherical microcapsules are used in self-healing applications, then ease of manufacture is maintained, but susceptibility to mechanical trauma and release efficiency are reduced

Engineering Contradiction:

Improveproduction simplicityVSAvoidrelease upon trauma

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by producing elongated capsules instead of spherical ones. The elongated shape creates stress concentration points along the length of the capsule, making them more susceptible to mechanical trauma and rupture. This asymmetric geometry enhances release efficiency when needed while the emulsion process maintains ease of manufacture, resolving the contradiction between spherical simplicity and trauma-responsive reliability.

Inventive Principle:

Principle #4Asymmetry

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

This method enables the efficient delivery of contents from elongated microcapsules, which are more susceptible to breaking and releasing their payload upon mechanical trauma or alkaline conditions, effectively addressing the limitations of spherical microcapsules in self-healing and corrosion detection applications.

Implementation Method 1

Spherical, or somewhat spherically shaped, microcapsules are normally formed due to the interfacial tension between the dispersed phase and the continuous phase

Methodology Applied

Scientific EffectInterfacial tension: Surface Tension

Implementation Method 2

shearing an emulsion between two surfaces moving at different velocities

Methodology Applied

Scientific EffectShear flow: Shear Stress

Data Source

PatentUS9108178B2Elongated microcapsules and their formation

Publication Date: 2015.08.18 UNITED STATES OF AMERICA AS REPRESENTED BY THE ADMINISTRATOR NAT AERONAUTICS & SPACE ADMINISTRATION

AI summary

Elongated microcapsules, such as elongated hydrophobic-core and hydrophilic-core microcapsules, may be formed by pulse stirring an emulsion or shearing an emulsion between two surfaces moving at different velocities. The elongated microcapsules may be dispersed in a coating formulation, such as paint.