Sulfonated Diketopyrrolopyrrole Pigment Dispersants for Color Filters
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Solution Overview
Problem
Conventional pigment dispersants for color filters, particularly those using diketopyrrolopyrrole pigments, face challenges with viscosity increase, flocculation, and storage stability, leading to inadequate transparency and consistency in color filters, especially for large-size displays.
Innovation Solution
A sulfonated composite diketopyrrolopyrrole pigment with controlled sulfonic groups (0.05 to 0.5) is used in combination with other sulfonic group-containing pigments or their salts, along with a cationic resin dispersant and resin varnish, to create a stable and transparent colored composition for color filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dispersers are used to disperse diketopyrrolopyrrole pigment, then the pigment can be dispersed, but the resulting dispersion lacks transparency and has insufficient transmission
Solution Approach 1:
The patent changes the chemical parameters of the dispersant by selecting specific polymers with particular functional groups (carboxyl, hydroxyl, or amine groups) and controlled molecular weights. This parameter optimization enables the dispersant to effectively separate pigment aggregates while maintaining high transparency, resolving the contradiction between dispersion quality and transparency.
Solution Approach 2:
The patent employs composite dispersant systems combining polymers with specific functional groups in optimized ratios. This composite approach creates a synergistic effect that enhances both dispersion stability and optical transparency, simultaneously improving manufacturing precision and reliability.
2Quantity of substance
If acrylic resin of high acid value is used in pigment dispersion, then the pigment can be dispersed, but the particles undergo flocculation and viscosity rises
Solution Approach 1:
The patent optimizes the acid value parameter of the acrylic resin dispersant and controls the pigment concentration within specific ranges. By adjusting these parameters and selecting polymers with appropriate molecular weights and functional groups, the patent prevents flocculation while maintaining high pigment concentration and storage stability.
Solution Approach 2:
The patent introduces specifically designed polymer dispersants as intermediary substances between the pigment particles and the medium. These dispersants with controlled functional groups and molecular weights act as mediators that prevent direct interaction between pigment particles, eliminating flocculation and maintaining composition stability.
3Quantity of substance
If high pigment concentration is used in colored composition, then color strength is improved, but viscosity increases and dispersibility deteriorates
Solution Approach 1:
The patent changes the viscosity-related parameters by selecting polymers with specific molecular weights and architectural structures. This parameter optimization allows achieving high pigment concentration while controlling viscosity within acceptable ranges, resolving the contradiction between color strength and flow properties.
Solution Approach 2:
The patent uses composite dispersant formulations combining polymers with different molecular weights and functional groups. This composite structure provides optimal steric and electrostatic stabilization at high pigment concentrations, maintaining both color strength and acceptable viscosity through synergistic effects.
4Manufacturing precision
If pigment dispersion is applied by spin-coating to form colored film, then color pixels can be formed, but the coated layer rises at central part due to high viscosity
Solution Approach 1:
The patent optimizes the viscosity parameter of the colored composition by controlling pigment concentration and selecting polymers with appropriate molecular weights. This parameter adjustment ensures the composition has sufficiently low viscosity for uniform spin-coating, preventing central layer rise and achieving consistent pixel formation across large substrates.
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
This approach reduces viscosity, prevents flocculation, and enhances transparency and stability, resulting in high-quality color filters with improved spectral characteristics, light resistance, and durability.
Implementation Method 1
the particles of the pigment undergo flocculation, so that the viscosity of the pigment dispersion tends to rise
Data Source
AI summary
A pigment dispersant contains the following component (a) alone or the following components (a) and (b) in combination:Component (a): a composite pigment formed of a diketopyrrolopyrrole pigment having a sulfonic group and another diketopyrrolopyrrole pigment having no sulfonic group, wherein the number of sulfonic group per molecule of the diketopyrrolopyrrole pigments in the composite pigment is from 0.05 to 0.5; andComponent (b): a pigment other than the component (a), wherein the pigment has a sulfonic group or its metal salt, ammonium salt or amine salt.Also disclosed are a colored composition for color filters, a process for the fabrication of a color filter, the color filter fabricated by the process, an image display device including the color filter, and an information communication equipment including the image display device. These colored composition, process, color filter, image display device and information communication equipment all make either direct or indirect use of the pigment dispersant.