Inkjet Ink Composition Using Silane Coupling Agent for Pigment Dispersion
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Solution Overview
Problem
Inkjet image forming methods face challenges with organic pigments like violet, orange, green, and blue, which have low dispersibility, leading to image unevenness and discharge failures due to pigment aggregation and increased ink viscosity, especially when using conventional polymer dispersants.
Innovation Solution
An inkjet ink composition incorporating specific organic pigments with a benzoxazole derivative and a comb block copolymer polymer dispersant, along with a photocurable compound and photopolymerization initiator, enhances pigment dispersibility and stability, preventing aggregation and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional polymer dispersants are used with organic pigments (violet, orange, green, blue), then the ink formulation is simple, but the pigment dispersibility is insufficient leading to aggregation and increased viscosity
Solution Approach 1:
The patent introduces a silane coupling agent as an intermediary substance that mediates between the organic pigment and polymer dispersant. The silane coupling agent has both organophilic groups that interact with organic pigments and hydrophilic groups that interact with polymer dispersants, effectively bridging the interface between hydrophobic pigments and hydrophilic dispersants to achieve stable dispersion
Solution Approach 2:
The patent uses a composite dispersing system combining polymer dispersants with silane coupling agents. This composite approach leverages the steric stabilization from polymer chains and the chemical bonding capability of silane groups, creating a synergistic effect that significantly improves pigment dispersion stability compared to using polymer dispersants alone
2Quantity of substance
If pigment concentration is increased to improve color saturation, then the color gamut is enhanced, but pigment aggregation occurs causing satellite and mist phenomena
Solution Approach 1:
The silane coupling agent acts as a spacer and mediator between pigment particles, preventing direct pigment-particle contact that leads to aggregation. By increasing the distance between pigment particles and providing steric hindrance, the silane coupling agent enables higher pigment concentrations to be achieved without satellite or mist formation
Solution Approach 2:
The patent modifies the chemical and physical parameters of the dispersion system by introducing silane coupling agents with specific functional groups. This changes the interfacial properties between pigment and dispersant, enabling stable dispersion at higher pigment concentrations that would otherwise cause aggregation and image defects
3Quantity of substance
If ink viscosity is increased to improve pigment loading, then more pigment can be dispersed, but discharge performance deteriorates due to satellite formation
Solution Approach 1:
The silane coupling agent serves as a lubricating intermediary between pigment particles and the continuous phase, reducing inter-particle friction and maintaining ink fluidity even at high pigment loadings. This intermediary effect prevents viscosity increase from compromising discharge performance
Solution Approach 2:
The patent optimizes the molecular weight, functional group composition, and concentration of the silane coupling agent to achieve the desired balance between pigment loading and ink viscosity. By carefully controlling these parameters, the ink maintains appropriate rheological properties for successful discharge while carrying high pigment concentrations
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 enhanced dispersibility of organic pigments results in reduced image unevenness and dot defects, ensuring stable inkjet printing with improved discharge performance and image quality.
Implementation Method 1
Ink containing a photocurable compound, which cures on being irradiated with actinic radiation
Data Source
AI summary
The purpose of the present invention is to provide: an inkjet ink composition having high dispersion stability of an organic pigment, and an image formation method using same. The present invention is an inkjet ink composition that contains: an organic pigment that includes C.I. Pigment Violet 23, C.I. Pigment Violet 32, C.I. Pigment Violet 37, C.I. Pigment Violet 39, C.I. Pigment Orange 36, C.I. Pigment Orange 38, C.I. Pigment Orange 43, C.I. Pigment Orange 64, C.I. Pigment Orange 71, C.I. Pigment Green 7, C.I. Pigment Green 36, C.I. Pigment Blue 15:6, C.I. Pigment Blue 25 or C.I. Pigment Blue 60; a benzoxazole derivative; a polymer dispersing agent; a photopolymerizable compound; and a photopolymerization initiator.