Polyisocyanate Composition for Low-Temperature Polyaspartic Coatings

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Solution Overview

Problem

Existing polyaspartic coating compositions do not adequately address the suppression of crystallization and maintain good appearance, weather resistance, and elongation at low temperatures, particularly at -20°C.

Innovation Solution

A polyisocyanate composition comprising specific ratios of aliphatic or alicyclic diisocyanates and polyols with controlled molar ratios of functional groups, including urethane and allophanate groups, is used to form a polyaspartic coating composition that suppresses crystallization and enhances low-temperature elongation and weather resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a polyisocyanate composition with high solid content is used to reduce diluent solvent, then the curing rate and mechanical strength are improved, but the crystallization of the polyisocyanate composition is not suppressed and low-temperature elongation deteriorates

Engineering Contradiction:

Improvecuring rateVSAvoidlow-temperature elongation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the molecular weight of polyols (200-2000) and the molar ratio of allophanate groups to urethane groups (2/98 or more and 30/70 or less). These parameter adjustments modify the polyisocyanate composition's properties to achieve both high solid content and suppressed crystallization, thereby maintaining low-temperature elongation while improving curing rate.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polyisocyanate composition containing multiple functional groups (urethane groups, allophanate groups, and optionally isocyanurate groups and uretdione groups) in specific ratios. This composite structure combines the benefits of rapid curing from allophanate groups with the crystallization suppression and flexibility from controlled urethane group content, resolving the contradiction between curing rate and low-temperature elongation.

Inventive Principle:

Principle #40Composite materials

2Strength

If the content of allophanate groups is increased to improve curing rate, then the mechanical strength is improved, but the crystallization is promoted and appearance and weather resistance deteriorate

Engineering Contradiction:

Improvemechanical strengthVSAvoidcrystallization

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by setting the molar ratio of allophanate groups to urethane groups within a specific range (2/98 or more and 30/70 or less) and controlling the molecular weight of polyols (200-2000). These parameter adjustments ensure that allophanate groups provide mechanical strength while the controlled ratio and molecular weight prevent excessive crystallization, maintaining appearance and weather resistance.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the molecular weight of polyol is reduced to lower viscosity, then the ease of formulation is improved, but the crystallization temperature is lowered and low-temperature elongation deteriorates

Engineering Contradiction:

Improveviscosity controlVSAvoidlow-temperature elongation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by optimizing the molecular weight of polyols to a specific range (200-2000) and controlling the average number of hydroxyl groups (2 or 3). This parameter optimization achieves low enough viscosity for easy formulation while maintaining a molecular weight high enough to prevent excessive crystallization and preserve low-temperature elongation properties.

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 a coating film with improved low-temperature elongation, weather resistance, and appearance by using a polyisocyanate with controlled functional group ratios, suitable for high-solid formulations.

Implementation Method 1

the polyisocyanate composition... can suppress crystallization

Methodology Applied

Scientific EffectCrystallization suppression: Crystallisation

Implementation Method 2

the polyisocyanate contains both a urethane group and an allophanate group within a single molecule

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentEP4647452A1Polyisocyanate composition, polyaspartic coating composition, and coating film

Publication Date: 2025.11.12 ASAHI KASEI KOGYO KABUSHIKI KAISHA

AI summary

The present invention provides a polyisocyanate composition comprising a polyisocyanate derived from at least one diisocyanate selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate, and at least one polyol selected from the group consisting of a polyester polyol and a polyoxyalkylene polyol, wherein the polyol has a number average molecular weight of 200 or more and 2,000 or less and an average number of hydroxyl groups of 2 or 3, the polyisocyanate contains both a urethane group and an allophanate group within a single molecule, and a molar ratio of allophanate groups to urethane groups is 2/98 or more and 30/70 or less.