Block Copolymer Pigment Dispersion Stability
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Solution Overview
Problem
Current polymers used as wetting and dispersing agents in color filters for liquid crystal displays face challenges in achieving low viscosity, storage stability, and compatibility with other components, while also ensuring no negative impact on the developing step, particularly with increased pigment loading.
Innovation Solution
A block co-polymer comprising two distinct blocks, where the first block includes multiple types of ether groups and is derived from ethylenically unsaturated monomers like acrylic and methacrylic esters, and the second block contains tertiary amino groups, allowing for the formation of a low-viscosity, storage-stable pigment dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional polymers are used as wetting and dispersing agents, then pigment loading can be increased, but viscosity increases and storage stability deteriorates
Solution Approach 1:
The polymer is divided into two distinct blocks: a hydrophilic block containing polyether chains (from monomers with ether groups) and a hydrophobic block containing amino groups. This segmentation allows the hydrophilic block to provide water solubility and storage stability, while the hydrophobic block provides pigment affinity and dispersing capability, enabling high pigment loading without sacrificing storage stability.
Solution Approach 2:
The invention uses a composite block copolymer structure combining two different polymer blocks with complementary properties. The hydrophilic polyether block and the hydrophobic amino-containing block work synergistically to achieve both high pigment loading capacity and excellent storage stability, resolving the contradiction between quantity of pigment and stability of dispersion.
2Quantity of substance
If conventional dispersants are used, then pigment loading increases, but viscosity increases
Solution Approach 1:
The segmented block structure allows the hydrophilic polyether block to interact with water/developer and the hydrophobic amino block to interact with pigment particles. This segmentation creates an efficient interface that reduces the amount of dispersant needed, thereby maintaining low viscosity even at high pigment loadings.
Solution Approach 2:
The invention changes the chemical structure parameters of the dispersant by using specific block copolymer architecture with controlled molecular weights and compositions. This parameter optimization enables the dispersant to be more efficient at lower concentrations, achieving high pigment loading without significant viscosity increase.
3Quantity of substance
If more wetting and dispersing agent is used to accommodate increased pigment loading, then pigment loading increases, but the developing step is negatively influenced
Solution Approach 1:
The segmented block structure provides clear functional separation: the hydrophilic polyether block ensures water solubility for easy developer penetration, while the hydrophobic amino block provides pigment affinity. This segmentation allows the dispersant to perform its function effectively at lower concentrations, preventing interference with the developing step while maintaining high pigment loading.
4Quantity of substance
If conventional polymers are used, then pigment loading increases, but compatibility with other components deteriorates
Solution Approach 1:
The block copolymer structure provides dual compatibility: the hydrophilic polyether block is compatible with water-based developers and other hydrophilic components, while the hydrophobic amino block is compatible with pigment particles and hydrophobic resins. This segmentation enables the dispersant to bridge different component types, maintaining formulation stability and compatibility even at high pigment loadings.
Data Source
AI summary
The invention relates to a block co-polymer comprising at least one first block and at least one second block which is different from the first block, wherein the first block comprises repeating units 1, and the second block comprises repeating units 2, wherein Z represents O or NH, R1 represents H or CH3, R2 represents a group selected from hydrocarbyl groups and ether group-containing groups, R3 represents an organic group having 2 to 4 carbon atoms, R4 and R5 independently represent an organic group, wherein R4 and R5 are optionally linked to each other to form a cyclic structure, and wherein the first block comprises wherein the first block comprises at least two different types of repeating units comprising ether groups.