Self-Emulsifying Polyisocyanate Dispersion Stability

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Solution Overview

Problem

Existing self-emulsifying polyisocyanate compositions face challenges with temperature-dependent particle diameter changes, leading to decreased dispersion stability.

Innovation Solution

A self-emulsifying polyisocyanate composition is developed, comprising a reaction mixture of an anionic compound, a nonionic hydrophilic group-containing monofunctional alcohol, an organic polyisocyanate, and a tertiary amine, with specific formulations to minimize temperature-dependent particle diameter changes and enhance dispersion stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If nonionic hydrophilic group-containing monofunctional alcohol is used to modify polyisocyanate, then emulsification in water is achieved, but particle diameter increases and dispersion stability decreases at temperatures above clouding point

Engineering Contradiction:

Improvedispersion stabilityVSAvoidparticle diameter

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical parameters of the hydrophilic modification by using anionic compounds (sulfonic acid or carboxylic acid groups) instead of nonionic hydrophilic groups. This parameter change eliminates temperature-dependent clouding behavior, maintaining small particle diameter (200-400 nm) and high dispersion stability across a wide temperature range (5-40°C).

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite modified polyisocyanate structure combining anionic compound (for water solubility and small particle size), nonionic hydrophilic group-containing monofunctional alcohol (for steric stabilization), and polyisocyanate (for crosslinking reactivity). This composite approach leverages the advantages of both anionic and nonionic modifiers while avoiding their individual disadvantages.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If anionic hydrophilic group-containing amine is used to create self-emulsifying polyisocyanate, then temperature dependency is reduced, but particle diameter becomes large and precipitation occurs

Engineering Contradiction:

Improvetemperature dependencyVSAvoiddispersion stability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent optimizes the anionic compound content to 0.05-0.10 mmol/g, which provides sufficient water solubility without excessive charge repulsion that would cause large particle formation. This precise parameter control achieves small particle diameter (200-400 nm) while maintaining temperature independence.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent combines anionic compound (for water solubility) with nonionic hydrophilic group-containing monofunctional alcohol (at 2-10 mass%, for steric stabilization). This composite structure prevents precipitation while maintaining small particle size and temperature-independent dispersion stability.

Inventive Principle:

Principle #40Composite materials

3Reliability

If high content of nonionic hydrophilic group-containing monofunctional alcohol is used, then emulsification is enhanced, but particle diameter increases

Engineering Contradiction:

ImproveemulsificationVSAvoidparticle diameter

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent optimizes the nonionic hydrophilic group-containing monofunctional alcohol content to 2-10 mass%, which provides sufficient emulsification and steric stabilization without excessive particle growth. This optimized parameter achieves small particle diameter (200-400 nm) while maintaining excellent dispersion stability.

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 composition achieves excellent dispersion stability with minimal temperature-dependent particle diameter changes, as evaluated by dynamic light scattering methods, ensuring stability across varying temperatures.

Implementation Method 1

a neutralization reaction between the component (a) and the component (d) occurs

Methodology Applied

Scientific EffectNeutralization reaction:

Implementation Method 2

the component (b) reacts with the component (c) to form a urethane bond (a urethanization reaction)

Methodology Applied

Scientific EffectUrethanization reaction:

Implementation Method 3

a secondary amino group of a reactant generated in the neutralization reaction reacts with the isocyanate group of the component (c) to form a urea bond (a ureaization reaction)

Methodology Applied

Scientific EffectUreaization reaction:

Implementation Method 4

as evaluated by dynamic light scattering methods, ensuring stability across varying temperatures

Methodology Applied

Scientific EffectDynamic light scattering:

Data Source

PatentUS12286554B2Self-emulsifying polyisocyanate composition, two-pack type coating composition and coating film

Publication Date: 2025.04.29 TOSOH CORP

AI summary

The present invention relates to a self-emulsifying polyisocyanate composition including a reaction mixture of (a) an anionic compound having a specific structure, (b) nonionic hydrophilic group-containing monofunctional alcohol having a specific structure, (c) organic polyisocyanate, and (d) tertiary amine, a two-part coating composition that contains the composition, and a coating film that can be obtained from the coating composition.