Dual-Curing Coating Composition for Water-Resistant Films

Solution Overview

Problem

Existing coating compositions face challenges in balancing crosslinking density and speed, and they lack sufficient water resistance, particularly when using alternatives to aziridine as crosslinking agents.

Innovation Solution

A coating composition comprising an aqueous dispersion of carboxyl functional polymer, epoxy silane as a first crosslinking agent, and isocyanate with alkoxysilane groups as a second crosslinking agent, which forms a double crosslinked structure to enhance water resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If epoxy silane and carbodiimide are used to replace aziridine as crosslinking agents, then worker safety is improved (aziridine sensitization eliminated), but crosslinking density and crosslinking speed deteriorate (far from requirements, huge gap in water resistance)

Engineering Contradiction:

Improveworker safetyVSAvoidwater resistance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent combines epoxy silane and carbodiimide into a composite crosslinking system. The epoxy silane provides initial crosslinking and forms a network structure, while the carbodiimide subsequently reacts with remaining hydroxyl groups to enhance crosslinking density. This composite approach achieves both worker safety (no aziridine) and sufficient water resistance through synergistic crosslinking mechanisms.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the ratio and concentration of epoxy silane and carbodiimide to achieve optimal crosslinking performance. By adjusting these parameters, the system achieves adequate crosslinking density and speed without using hazardous aziridine, thus improving water resistance while maintaining worker safety.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If epoxy silane and carbodiimide are used as crosslinking agents, then worker safety is improved, but crosslinking speed deteriorates (far from requirements)

Engineering Contradiction:

Improveworker safetyVSAvoidcrosslinking speed

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The patent designs a sequential crosslinking process where epoxy silane reacts first to form an initial network, followed by carbodiimide reaction with remaining hydroxyl groups. This continuous crosslinking action ensures that crosslinking speed meets requirements while avoiding aziridine for worker safety.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent adjusts the concentration and ratio of epoxy silane and carbodiimide to optimize crosslinking speed. By carefully controlling these parameters, the system achieves adequate crosslinking speed without using hazardous aziridine, thus improving water resistance while maintaining worker safety.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If epoxy silane and carbodiimide are used as crosslinking agents, then worker safety is improved, but crosslinking density deteriorates (far from requirements)

Engineering Contradiction:

Improveworker safetyVSAvoidcrosslinking density

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent combines epoxy silane and carbodiimide into a composite crosslinking system. The epoxy silane provides initial crosslinking and forms a network structure, while the carbodiimide subsequently reacts with remaining hydroxyl groups to enhance crosslinking density. This composite approach achieves both worker safety (no aziridine) and sufficient water resistance through synergistic crosslinking mechanisms.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the ratio and concentration of epoxy silane and carbodiimide to achieve optimal crosslinking performance. By adjusting these parameters, the system achieves adequate crosslinking density and speed without using hazardous aziridine, thus improving water resistance while maintaining worker safety.

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 double crosslinked structure significantly improves water resistance, making the coating suitable for applications requiring higher durability and weather resistance.

Implementation Method 1

a first crosslinking agent comprising an epoxy silane

Methodology Applied

Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

a second crosslinking agent comprising an isocyanate which contains at least one alkoxysilane group

Methodology Applied

Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 3

isocyanate which contains at least one alkoxysilane group

Methodology Applied

Scientific EffectSilane crosslinking: Chemical Bonding

Data Source

PatentEP4208512B1A coating composition, an article made thereof and a process for preparing the same

Publication Date: 2025.07.09 SHERWIN WILLIAMS (GUANGDONG) NEW MATERIAL CO LTD

AI summary

The present application relates to a coating composition, a process for preparing the coating composition and an article containing a coating formed by the coating composition. It relates in particular to a dual-curing coating system, comprising: a film-forming resin composition comprising an aqueous dispersion of at least one carboxyl functional polymer; a first crosslinking agent comprising an epoxy silane; and a second crosslinking agent comprising an isocyanate.