Aqueous pigment dispersion
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Solution Overview
Problem
Ink-jet printing technologies face challenges with ink clogging in nozzles due to flocculated thickened products, leading to reduced redispersibility and water resistance, especially when printing on low-water absorbing media, and existing solutions do not adequately address storage stability and nozzle clogging issues.
Innovation Solution
A pigment water dispersion containing water-insoluble crosslinked polymer particles, a water-soluble basic compound, and water, where the crosslinked polymer has a specific saponification value and ester group structure, is used to create a water-based ink that maintains redispersibility and provides excellent water resistance and storage stability, employing a process involving dispersion treatment and crosslinking to enhance ink properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional aqueous pigment dispersions are used, then ink can be applied to printing media, but the ink forms flocculated thickened products that clog nozzles and reduce redispersibility
Solution Approach 1:
The patent changes the chemical parameters of the dispersion system by introducing a water-soluble polymeric compound with specific functional groups (carboxyl, hydroxyl, or amine groups) that reacts with the pigment particles. This chemical modification prevents flocculation and maintains redispersibility without causing nozzle clogging, resolving the contradiction between reliability and compositional stability.
Solution Approach 2:
The patent creates a composite dispersion system combining pigment particles with a water-soluble polymeric compound having specific functional groups. This composite structure prevents flocculation while maintaining stability, addressing both the nozzle clogging issue and the dispersion stability requirement simultaneously.
2Object-affected harmful factors
If ink is formulated for water resistance, then water resistance improves, but storage stability and redispersibility deteriorate
Solution Approach 1:
The patent modifies the chemical parameters by selecting polymeric compounds with specific functional groups (carboxyl, hydroxyl, or amine groups) that provide water resistance through controlled interaction with water while maintaining storage stability. The molecular weight range (1,000-1,000,000) is optimized to balance water resistance with redispersibility and storage stability.
Solution Approach 2:
The water-soluble polymeric compound acts as an intermediary between the pigment particles and water, providing water resistance while preventing direct harmful interactions that would cause flocculation or instability. The polymer mediates the interaction to achieve both water resistance and storage stability.
3Ease of operation
If ink is printed on low-water absorbing media, then printing capability is achieved, but redispersibility and water resistance are insufficient
Solution Approach 1:
The patent changes the chemical parameters of the ink formulation by incorporating polymeric compounds with specific functional groups and molecular weights that enhance redispersibility and water resistance. These parameter changes enable the ink to perform reliably on low-water absorbing media without sacrificing redispersibility or water resistance.
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 resulting water-based ink exhibits improved redispersibility, water resistance, and storage stability, preventing nozzle clogging and ensuring high-quality prints on low-water absorbing media, while maintaining the ink's performance over time.
Implementation Method 1
a water-insoluble crosslinked polymer A constituting the particles has a carboxy group and a crosslinked structure containing an ester group derived from a water-insoluble crosslinking agent
Implementation Method 2
a saponification value of the water-insoluble crosslinked polymer A is not less than 170 mgKOH/g and not more than 300 mgKOH/g
Implementation Method 3
the water-soluble basic compound contains a water-soluble amine compound, wherein the boiling point of the water-soluble amine compound is not lower than 100°C and not higher than 350°C
Data Source
AI summary
The present invention relates to a pigment water dispersion containing pigment-containing water-insoluble crosslinked polymer A particles, a water-soluble basic compound and water, in which a water-insoluble crosslinked polymer A constituting the particles has a carboxy group and a crosslinked structure containing an ester group derived from a water-insoluble crosslinking agent, a saponification value of the water-insoluble crosslinked polymer A is from 170 to 300 mgKOH/g, and the water-soluble basic compound contains a water-soluble amine compound; a process for producing the pigment water dispersion; a water-based ink for ink-jet printing which contains the pigment water dispersion; and an ink-jet printing method using the water-based ink.