Color Filter Dispersant via Controlled Radical Polymerization
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Solution Overview
Problem
There is a need for dispersants with improved dispersing properties in color filter compositions to enhance the production of color filters, as existing methods do not fully address the requirements for precision, durability, and defect reduction.
Innovation Solution
A color filter composition comprising a photoresist binder, a transparent pigment, and a dispersant polymer or copolymer obtained through a controlled radical polymerization process, specifically using nitroxylether or stable free nitroxyl radicals, followed by a transesterification reaction, to improve dispersing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dispersants are used in color filter compositions, then the basic pigment dispersion can be achieved, but the dispersing properties are insufficient leading to reduced manufacturing precision and increased defects
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the dispersant through controlled radical polymerization to create copolymers with specific monomer ratios and molecular weights. The dispersant is synthesized using nitroxylether or stable free nitroxyl radicals as controlling agents, creating polymers with optimized chain lengths and architectures that enhance dispersing capability while maintaining manufacturing precision
Solution Approach 2:
The patent employs composite materials by creating copolymer dispersants that combine multiple monomer units (including C1-C6 alkyl or hydroxy C1-C6 alkyl esters of acrylic or methacrylic acid, and other functional monomers) within a single polymer structure. This composite polymer structure provides both dispersing functionality and compatibility with the pigment and photoresist binder system
2Reliability
If existing dispersant formulations are used, then pigment dispersion can be achieved, but durability such as light resistance and thermal resistance is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing the controlled radical polymerization dispersant before incorporating it into the color filter composition. The dispersant is prepared in advance through controlled polymerization using nitroxylether or stable free nitroxyl radicals, ensuring optimal dispersing properties are built into the formulation before the actual color filter manufacturing process begins
Solution Approach 2:
The patent replaces conventional mechanical mixing and dispersing methods with a chemically engineered dispersant system. Instead of relying solely on mechanical energy input during manufacturing, the patent uses a chemically designed copolymer dispersant that provides passive, molecular-level dispersion stability, thereby improving durability without requiring complex mechanical processing
3Manufacturing precision
If conventional pigment dispersion methods are used, then color filter layers can be formed, but defects such as pinholes are increased
Solution Approach 1:
The patent introduces an intermediary substance - the controlled radical polymerization copolymer dispersant - that mediates between the pigment particles and the photoresist binder. This dispersant acts as a molecular bridge, ensuring uniform pigment distribution and proper film formation without creating defects, thereby improving both film thickness uniformity and eliminating pinhole defects
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 solution provides improved dispersing properties, leading to enhanced precision, durability, and reduced defects in color filter production, specifically in the pigment dispersion method.
Implementation Method 1
polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one nitroxylether having the structural element... or a2) polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one stable free nitroxyl radical and a free radical initiator
Implementation Method 2
comprising the modification of the polymer or copolymer prepared under a1) or a2) by a transesterification reaction using an alcohol
Data Source
AI summary
The invention relates to a color filter composition comprising a) a photoresist binder, b) a transparent pigment, c) optionally a solvent and/or optionally a photoinitiator or a photolatent catalyst, d) a dispersant which is a polymer or copolymer obtainable by a process comprising the steps of a1) polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one nitroxylether having the structural element wherein X represents a group having at least one carbon atom and is such that the free radical X derived from X is capable of initiating polymerization; or a2) polymerizing in a first step one or more ethylenically unsaturated monomers in the presence of at least one stable free nitroxyl radical and a free radical initiator; wherein at least one monomer used in the steps a1) or a2) is a C1-C6 alkyl or hydroxy C1-C6 alkyl ester of acrylic or methacrylic acid; and a second step b) comprising the modification of the polymer or copolymer prepared under a1) or a2) by a transesterification reaction, an amidation, hydrolysis or anhydride modification or a combination thereof, and optionally in addition by quaternization.