Pigment Water Dispersion Stability via Formaldehyde Plasticization

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Solution Overview

Problem

Pigment water dispersions with crosslinked polymers, even with high acid values, often fail to exhibit expected storage stability, especially under high-temperature conditions due to restricted acid group disposition and reduced charge repulsion between polymer particles.

Innovation Solution

Incorporating a formaldehyde-releasing compound to accelerate the plasticization of crosslinked polymers, allowing acid groups to effectively contribute to charge repulsion and prevent aggregation of polymer particles, thereby maintaining stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a crosslinked polymer with high acid value is used to enhance charge repulsion, then storage stability should improve, but the crosslinked structure restricts acid group disposition and reduces effectiveness

Engineering Contradiction:
Improvestorage stabilityVSAvoidacid group disposition freedom
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a formaldehyde-releasing compound that gradually releases formaldehyde during storage, which then reacts with the crosslinked polymer to plasticize it and restore acid group mobility before storage stability issues arise. This preliminary action prevents the deterioration of storage stability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Formaldehyde acts as an intermediary substance that mediates between the rigid crosslinked structure and the acid groups. The formaldehyde-releasing compound provides formaldehyde in situ, which temporarily breaks crosslinks or plasticizes the matrix, allowing acid groups to move freely and maintain charge repulsion effectiveness.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If formaldehyde-releasing compound is added to plasticize crosslinked polymer, then acid group mobility and charge repulsion improve, but additional components increase formulation complexity

Engineering Contradiction:
Improvestorage stabilityVSAvoidformulation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The formaldehyde-releasing compound serves multiple functions simultaneously: it acts as a plasticizer for the crosslinked polymer, a source of formaldehyde for modulating polymer flexibility, and a storage stability enhancer. This multi-functionality reduces the need for separate additives and simplifies the overall formulation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The formaldehyde-releasing compound provides formaldehyde in situ within the pigment dispersion system, eliminating the need for external formaldehyde application. The system self-regulates the plasticization process through controlled formaldehyde release, maintaining storage stability autonomously.

Inventive Principle:
Principle #25Self-service

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 pigment water dispersion demonstrates enhanced storage stability even under high-temperature conditions for extended periods, ensuring the dispersion remains stable and effective.

Implementation Method 1

Incorporating a formaldehyde-releasing compound to accelerate the plasticization of crosslinked polymers, allowing acid groups to effectively contribute to charge repulsion

Methodology Applied
Scientific EffectPlasticization:

Implementation Method 2

allowing acid groups to effectively contribute to charge repulsion and prevent aggregation of polymer particles

Methodology Applied
Scientific EffectCharge repulsion: Ion Repulsion/Attraction

Data Source

PatentUS11077692B2Aqueous pigment dispersion
Publication Date: 2021.08.03 KAO CORP

AI summary

The present invention relates to a pigment water dispersion containing a pigment, a crosslinked polymer and water, in which the crosslinked polymer is prepared by crosslinking a carboxy group-containing polymer with a crosslinking agent, and has an acid value of not less than 70 mgKOH/g and not more than 300 mgKOH/g; and the pigment water dispersion further contains a formaldehyde-releasing compound. The pigment water dispersion of the present invention is excellent in storage stability even when being stored under high-temperature conditions for a long period of time.