Curable Composition for Color Filters with Acid-Group Binder Resin
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Solution Overview
Problem
Current curable compositions for color filters in LCDs and solid-state image pickup devices face challenges with low sensitivity, poor storage stability, and inadequate adhesiveness to substrates due to high concentrations of coloring agents, leading to issues like pigment aggregation, reduced developability, and storage stability problems.
Innovation Solution
A curable composition comprising a polymerizable compound, a photopolymerization initiator, and a binder resin with an acid group and unsaturated double bond, where the binder resin has a specific structure with an acid group linked via a linking group and unsaturated double bonds on a side chain, allowing for high sensitivity and improved storage stability even at high coloring agent concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the content of coloring agent is increased to improve color purity, then color purity is improved, but curability is deteriorated due to reduced photopolymerization initiator and monomer content
Solution Approach 1:
The patent changes the chemical structure parameters of the binder resin, specifically introducing acid groups with specific pKa values (3-7) and controlling the ratio of acid groups to hydroxyl groups (0.1-5.0 mol/mol). This parameter optimization allows the system to maintain curability at high coloring agent concentrations by reducing unwanted interactions while preserving adhesion and color purity.
Solution Approach 2:
The patent creates a composite binder resin system combining specific acid groups (carboxylic acid, sulfonic acid, or phosphoric acid) with hydroxyl groups in controlled ratios. This composite structure synergistically provides both adhesion to substrates and compatibility with high concentrations of coloring agents without compromising curability, resolving the contradiction between color purity and curability.
2Manufacturing precision
If pigment particle size is reduced to improve contrast, then contrast is improved, but storage stability deteriorates due to pigment aggregation
Solution Approach 1:
The binder resin acts as an intermediary between fine pigment particles and the dispersion medium. The specific acid groups in the binder resin interact with the pigment surface, preventing aggregation while maintaining fine particle size for high contrast. This intermediary function resolves the contradiction between contrast improvement and storage stability.
Solution Approach 2:
The patent optimizes the molecular weight of the binder resin (1,000-100,000) and the ratio of acid groups to hydroxyl groups (0.1-5.0 mol/mol), creating optimal steric and electrostatic barriers that prevent fine pigment aggregation while maintaining dispersion stability for high-contrast applications.
3Stability of the object's composition
If dispersing agent content is increased to improve dispersion stability, then dispersion stability is improved, but developability deteriorates due to bridge formation between pigments
Solution Approach 1:
The patent extracts and eliminates the need for separate dispersing agents by incorporating dispersing functions directly into the binder resin structure. The acid groups in the binder resin provide sufficient dispersion stability without causing bridge formation, thereby maintaining both dispersion stability and developability.
Solution Approach 2:
The binder resin performs multiple functions simultaneously: adhesion to substrates, dispersion of pigment particles, and prevention of aggregation. This multi-functional design eliminates the need for separate dispersing agents, resolving the contradiction between dispersion stability and developability.
4Reliability
If resin content is increased to improve adhesiveness and developability, then adhesiveness is improved, but pigment aggregation is promoted due to hydrogen bond interactions
Solution Approach 1:
The patent precisely controls the pKa values of acid groups (3-7) and the ratio of acid groups to hydroxyl groups (0.1-5.0 mol/mol), optimizing the balance between adhesion and dispersion stability. This parameter control prevents excessive hydrogen bonding that would cause aggregation while maintaining sufficient adhesion.
Solution Approach 2:
The patent creates local quality differences in the binder resin by positioning acid groups and hydroxyl groups in specific ratios and configurations. This allows different regions of the resin to perform different functions: adhesion to substrates and prevention of pigment aggregation, resolving the contradiction between adhesiveness and dispersion stability.
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 composition achieves high sensitivity, excellent adhesiveness to substrates, and precise pattern formation with reduced color irregularities and development residue, enhancing productivity and image quality in color filters for both LCDs and solid-state image pickup devices.
Implementation Method 1
a photopolymerization initiator (B)
Implementation Method 2
a binder resin having an acid group and an unsaturated double bond (D)
Data Source
AI summary
A curable composition including (A) a compound which has a plurality of ethylenically unsaturated double bonds and secondary hydroxyl groups, (B) a photopolymerization initiator, and (C) a coloring agent, is used to provide a curable composition which exhibits excellent storage stability such as dispersion stability even in the case where a coloring agent is included at high concentration, highly sensitive curability by exposure, high adhesiveness to the surface of a hardening material in a curing region when applied in forming patterns on the surface of the hardening material, excellent uncured region removability, and excellent pattern formability; a color filter having colored patterns, which is formed by using the curable composition and has excellent resolution and adhesiveness to the support; and a manufacturing method of the coloring filter with high productivity.