Modified Polyisocyanate Composition for Low-VOC Water Dispersion

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Solution Overview

Problem

Existing water-dispersible polyisocyanates face issues with high viscosity, requiring high shear force for dispersion, poor storage stability, and increased VOC content due to solvent use, which affects dispersibility and environmental safety.

Innovation Solution

A modified polyisocyanate comprising an iminooxadiazinedione and isocyanurate structure, prepared through the reaction of aminosulfonic acid, polyisocyanate, tertiary amine, and optionally polyether alcohol, allowing for manual stirring and solvent-free dispersion, enhancing dispersibility and reducing VOC content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If polyether-modified polyisocyanate is used to improve water dispersibility, then dispersibility is improved, but crosslinking density is reduced and water resistance is permanently affected

Engineering Contradiction:

Improvewater dispersibilityVSAvoidcrosslinking density

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the chemical structure parameters by introducing cyclic carbonate groups and controlling the molecular weight distribution (specifically limiting high molecular weight fractions to 4.1-22%) to achieve both water dispersibility and maintained crosslinking density. This parameter optimization resolves the contradiction between dispersibility and crosslinking efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite molecular structure combining polyether modification with cyclic carbonate groups, achieving a balance between hydrophilicity (for dispersibility) and crosslinking reactivity. The dual-functional structure allows the material to exhibit both good water dispersibility and sufficient crosslinking density.

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If high shear force is applied to disperse polyether-modified polyisocyanate, then dispersibility is improved, but energy consumption and equipment requirements increase

Engineering Contradiction:

ImprovedispersibilityVSAvoidenergy consumption

Core Design Contradiction:

Ease of operationVSUse of energy by stationary object

Solution Approach 1:

The patent optimizes the molecular weight distribution parameters, specifically limiting the total amount of molecules with Mn>2700 to 4.1-22%, which significantly reduces the viscosity and shear resistance of the material. This allows the polyisocyanate to disperse easily in water with minimal energy input and simple stirring equipment.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If sulfonic acid group-modified polyisocyanate is used to improve water dispersibility, then dispersibility is improved, but VOC content increases due to solvent addition

Engineering Contradiction:

Improvewater dispersibilityVSAvoidVOC content

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition by using polyether modification with controlled molecular weight distribution instead of sulfonic acid groups, achieving water dispersibility through hydrophilic polyether chains without requiring solvent additives. This eliminates the VOC issue while maintaining good dispersibility.

Inventive Principle:

Principle #35Parameter changes

4Ease of operation

If carboxylic acid group-modified polyisocyanate is used to improve water dispersibility, then dispersibility is improved, but storage stability deteriorates

Engineering Contradiction:

Improvewater dispersibilityVSAvoidstorage stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical structure from carboxylic acid groups to polyether chains with cyclic carbonate groups. The polyether structure provides water dispersibility through hydrophilic chains while the cyclic carbonate groups and controlled molecular weight distribution prevent unwanted side reactions, ensuring excellent storage stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of polyether modification (which could reduce stability) into a benefit by carefully controlling the molecular weight distribution and introducing cyclic carbonate groups. The controlled structure prevents polymerization and gelation while maintaining water dispersibility, turning a potential stability issue into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12630667B2Modified polyisocyanate

Publication Date: 2026.05.19 COVESTRO DEUTSCHLAND AG

AI summary

The invention relates to a modified polyisocyanate and use thereof, especially as a crosslinking component in a water-soluble or water-dispersible coating composition. The modified polyisocyanate comprises iminooxadiazinedione structure and isocyanurate structure, wherein the weight ratio of the iminooxadiazinedione structure to the isocyanurate structure is not less than 1:5; and relative to the total weight of the modified polyisocyanate, the total amount of molecules with a number average molecular weight greater than 2700 g/mol in the modified polyisocyanate is 4.1% by weight to 22% by weight; and the modified polyisocyanate is obtainable by the reaction of: an aminosulfonic acid, a polyisocyanate; a tertiary amine; and optionally a polyether alcohol containing ethylene oxide groups.