pH-Sensitive Microcapsule with Porous Core for Paste Stability

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Solution Overview

Problem

Existing microcapsules used for storing components of redox initiator systems are not sufficiently stable to survive high shear forces encountered during the preparation of pasty compositions, and the mixing forces applied in paste/paste systems are not strong enough to break the microcapsules and release the active reagents effectively.

Innovation Solution

Development of pH-sensitive microcapsules with a mechanically stable hollow or porous core filled with active reagents and coated with a shell that swells or dissolves in acidic or basic environments, allowing controlled release of the reagents during mixing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If microcapsules are used for storing redox initiator components in paste/paste systems, then storage stability is improved, but the microcapsules cannot survive high shear forces during kneading processes

Engineering Contradiction:

Improvestorage stabilityVSAvoidmechanical stability under shear forces

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The microcapsule structure is divided into two distinct parts: a mechanically stable hollow or porous core that withstands shear forces, and a pH-sensitive shell that provides controlled release. This segmentation allows each part to fulfill its specific function - the core provides mechanical integrity while the shell provides pH-responsive release behavior.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The microcapsule employs a composite structure combining a mechanically robust core material (such as polymer or inorganic material) with a pH-sensitive shell material. This composite design enables the microcapsule to simultaneously exhibit mechanical stability for surviving kneading processes and pH-sensitivity for controlled reagent release.

Inventive Principle:

Principle #40Composite materials

2Productivity

If mixing forces are increased to break microcapsules for reagent release, then release effectiveness is improved, but the microcapsules become unstable during storage

Engineering Contradiction:

Improverelease effectivenessVSAvoidstorage stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention replaces mechanical breaking mechanisms with a chemical/pH-responsive release mechanism. Instead of relying on mechanical shear forces to break the microcapsule wall, the pH-sensitive shell automatically dissolves or becomes permeable when exposed to acidic or basic environments, enabling reagent release without requiring intense mixing forces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The microcapsule utilizes changes in pH as a triggering parameter for release. The pH-sensitive shell remains intact under neutral storage conditions but undergoes structural changes (dissolution, swelling, or permeability increase) when exposed to acidic or basic environments, thereby controlling reagent release based on pH parameter changes rather than mechanical force.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If a pH-sensitive shell is added to provide controlled release, then release control is improved, but device complexity increases

Engineering Contradiction:

Improverelease controlVSAvoidmicrocapsule structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The pH-sensitive shell acts as an intermediary layer between the core containing the reagent and the external environment. This intermediate structure mediates the release process by responding to pH changes in the environment, allowing controlled transfer of reagents from the core to the surrounding medium without direct exposure to harsh conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 pH-sensitive microcapsules ensure stable storage and controlled release of reagents, enabling the production of redox-curable paste/paste compositions by surviving kneading processes and releasing components on demand, thus overcoming the challenges of stability and release in existing technologies.

Implementation Method 1

a shell or coating which prevents the active reagent to migrate out of the porous or hollow core during storage. Thus, a reaction of the encapsulated components with component(s) surrounding the microcapsule is avoided.

Methodology Applied

Scientific EffectpH-sensitive dissolution:

Implementation Method 2

coated with a shell that swells or dissolves in acidic or basic environments, allowing controlled release of the reagents during mixing processes

Methodology Applied

Scientific EffectpH-sensitive swelling:

Data Source

PatentUS12194113B2Microcapsule with a porous or hollow core and ph-sensitive shell and use thereof

Publication Date: 2025.01.14 SOLVENTUM INTELLECTUAL PROPERTIES CO

AI summary

The invention relates to a microcapsule comprising a hollow or porous core, the hollow or porous core being composed of a polymeric material and containing a component of a redox-initiator system, a shell, the shell being composed of a pH-sensitive material. The microcapsule can be used for formulating dental materials.