Gelatin-Urethane Microcapsule Shells With Low Isocyanate Loading

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Solution Overview

Problem

Existing gelatin/isocyanate microcapsules face challenges in achieving improved strength, controlled release capabilities, and environmental safety while reducing the use of isocyanates, which are associated with environmental and health concerns.

Innovation Solution

The development of microcapsules formed through an oil-in-water microencapsulation process using a gelatin-derived shell and a reduced amount of isocyanates, specifically aliphatic and aromatic di- and/or poly-isocyanates, with a weight ratio of gelatin to isocyanate ranging from 1:0.5 to 1:0.01, allowing for improved shell strength and controlled release of benefit agents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If gelatin/isocyanate microcapsules are used to achieve shell strength and controlled release, then the shell strength and release control are improved, but environmental safety deteriorates due to isocyanate pollution and health concerns

Engineering Contradiction:

Improveshell strengthVSAvoidenvironmental safety

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by reducing isocyanate content from conventional levels to less than 10% by weight of the shell, while adjusting gelatin content to 90-99%. This parameter change maintains shell strength through optimized gelatin crosslinking while eliminating isocyanate-related environmental and health hazards

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extracts and removes the harmful isocyanate component from the microcapsule shell formulation, replacing it primarily with gelatin. This extraction eliminates the source of environmental pollution and health concerns while maintaining the functional integrity of the shell through alternative crosslinking mechanisms

Inventive Principle:

Principle #2Taking out (Extraction)

2Object-affected harmful factors

If isocyanate content is reduced to improve environmental safety, then environmental safety and health benefits are improved, but shell strength may deteriorate

Engineering Contradiction:

Improveenvironmental safetyVSAvoidshell strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent creates a composite shell structure using gelatin as the primary matrix material combined with minimal isocyanate crosslinking agents. This composite approach leverages gelatin's structural properties for shell strength while using trace isocyanates solely for crosslinking, achieving both environmental safety and mechanical integrity

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the gelatin molecular weight, crosslinking density, and ratio of crosslinking agents to achieve maximum shell strength at minimal isocyanate concentrations. By controlling crosslinking parameters, the shell maintains adequate strength and controlled release properties without requiring high isocyanate content

Inventive Principle:

Principle #35Parameter changes

3Duration of action of moving object

If conventional microencapsulation processes are used to achieve controlled release, then release control is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvecontrolled release capabilitiesVSAvoidmanufacturing process complexity

Core Design Contradiction:

Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The patent controls the degree of gelatin crosslinking and shell thickness parameters to inherently provide controlled release functionality. By adjusting these parameters during a simplified single-step emulsion process, the microcapsules achieve sustained release without requiring complex multi-layer structures or additional manufacturing steps

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 physical properties, controlled release capabilities, and improved degradability, while significantly reducing the use of isocyanates, thus offering environmental, health, and economic benefits.

Implementation Method 1

Interfacial polymerization is a process wherein a microcapsule wall of polyamide, an epoxy resin, a polyurethane, a polyurea or the like is formed at an interface between two phases

Methodology Applied

Scientific EffectInterfacial polymerization: Chemical Bonding