Inkjet Ink Copolymer Dispersion Stability

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Solution Overview

Problem

Current inkjet inks face challenges in maintaining long-term dispersion stability and achieving high print density, weather resistance, and fixability due to pigment aggregation, which affects productivity and image quality.

Innovation Solution

A copolymer comprising 10-96% cyclohexyl methacrylate, 1-50% acrylic acid, and 1-25% alkyl (meth)acrylate units, with optional styrene, is used to create an inkjet ink pigment dispersion with improved dispersibility and stability, ensuring excellent weather resistance and print quality while maintaining productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pigment dispersion is used in inkjet ink, then color density and weather resistance are improved, but pigment aggregation occurs during long-term storage reducing dispersion stability

Engineering Contradiction:
Improvedispersion stabilityVSAvoidpigment aggregation
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

A copolymer comprising a cyclohexyl methacrylate unit, an acrylic acid unit, and an alkyl (meth)acrylate unit is introduced as an intermediary dispersing agent. This copolymer mediates between the pigment particles and the ink medium, providing steric and electrostatic stabilization that prevents pigment aggregation during long-term storage while maintaining excellent dispersion stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses a composite polymer structure combining three different monomer units (cyclohexyl methacrylate, acrylic acid, and alkyl (meth)acrylate) in specific proportions. This composite material approach allows the dispersing agent to simultaneously provide hydrophobic interaction with pigment particles, electrostatic repulsion through carboxyl groups, and steric stabilization through the alkyl side chains, effectively resolving the contradiction between dispersion stability and pigment aggregation.

Inventive Principle:
Principle #40Composite materials

2Reliability

If polymer composition is modified to improve dispersion stability, then dispersibility is enhanced, but productivity decreases due to complex manufacturing processes

Engineering Contradiction:
Improvedispersion stabilityVSAvoidmanufacturing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The invention optimizes the compositional parameters of the copolymer, specifically setting the cyclohexyl methacrylate unit content at 30-70 mass%, acrylic acid unit at 10-40 mass%, and alkyl (meth)acrylate unit at 10-30 mass%. These parameter ranges achieve the optimal balance between dispersion stability and ease of manufacturing, allowing the copolymer to be synthesized through conventional polymerization processes without requiring complex modification steps.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If filter filtration or centrifugal separation is used to remove particles, then ink quality is improved, but productivity decreases due to frequent filter exchange and particle removal

Engineering Contradiction:
Improveink qualityVSAvoidproduction speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The copolymer dispersing agent performs preliminary stabilization of pigment particles during the ink formulation stage, preventing aggregation before the ink is subjected to filtration or centrifugal separation. This preliminary action ensures that particles remain individually dispersed and stable, significantly reducing the frequency of filter exchanges and particle removal operations during subsequent manufacturing and storage, thereby maintaining high productivity while ensuring ink quality.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2682437B8Inkjet ink copolymer, inkjet ink pigment dispersing element using same, and inkjet ink
Publication Date: 2019.10.02 SANYO COLOR WORKS

AI summary

To provide an inkjet ink polymer capable of providing an inkjet ink capable of forming a printed product having excellent weather resistance, print density (coloring properties), and fixability (abrasion properties) with good productivity and providing a pigment dispersion having excellent dispersibility with good productivity. An inkjet ink copolymer contains 10 to 99% by weight of a cyclohexyl methacrylate unit and 1 to 90% by weight of an acrylic acid unit. The purpose is achieved by an inkjet ink pigment dispersion containing the inkjet ink copolymer and a pigment.