Surface Modified Carbon Black Pigment Particles for Electronic Displays
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Solution Overview
Problem
Existing pigment dispersions for electronic displays face challenges in achieving long-term stability and performance due to issues like flocculation, aggregation, and sedimentation, often requiring high molecular weight polymers and surfactants that increase viscosity and alter interfacial surface tension, making them unsuitable for demanding electronic applications.
Innovation Solution
Surface modified pigment particles with functional groups that form covalent or hydrogen bonds with specific compounds, allowing for improved colloidal stability without the need for additional polymeric dispersants or surfactants, using a modifying compound that can be bonded to the pigment surface through chemisorption, ionic bonds, or hydrogen bonding, enhancing stability in both polar and non-polar media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high molecular weight polymers and surfactants are used to improve colloidal stability, then particle resistance to flocculation and aggregation is improved, but viscosity increases and interfacial surface tension is altered
Solution Approach 1:
The patent applies parameter changes by modifying the molecular weight of the polymer from high (prior art) to low (500-50,000 Da), and changing the chemical structure to include specific functional groups that provide steric and electrostatic stabilization. This parameter change resolves the contradiction by achieving colloidal stability without the high viscosity associated with high molecular weight polymers.
Solution Approach 2:
The patent applies local quality by introducing specific functional groups (carboxyl, hydroxyl, amine) at localized positions on the polymer chain that directly interact with pigment particle surfaces. This localized functional group distribution provides targeted stabilization at the particle interface while keeping the overall polymer molecular weight low, thus avoiding high viscosity throughout the bulk dispersion.
2Stability of the object's composition
If polymeric dispersants and surfactants are used to stabilize pigment dispersions, then colloidal stability is improved, but the dispersion becomes unsuitable for electronic applications due to altered interfacial properties
Solution Approach 1:
The patent changes the polymer parameters to low molecular weight (500-50,000 Da) and specific functional group composition (carboxyl, hydroxyl, amine) that do not significantly alter interfacial surface tension. This enables the dispersion to meet the stringent requirements of electronic applications while maintaining colloidal stability.
Solution Approach 2:
The patent uses polymers with molecular weights and functional group compositions that replicate the stabilizing effects of high molecular weight polymers and surfactants, but without their harmful side effects. The low molecular weight polymer copies the essential stabilization function while maintaining compatibility with electronic application requirements.
3Stability of the object's composition
If chemical surface modification with polymeric chains is performed, then colloidal stability is improved, but product performance deteriorates due to increased viscosity and low interfacial surface tension
Solution Approach 1:
The patent fundamentally changes the polymer molecular weight parameter from high to low (500-50,000 Da) and optimizes functional group content. This parameter change eliminates the harmful effects of increased viscosity and excessive interfacial surface tension reduction while preserving colloidal stability through steric and electrostatic mechanisms.
Solution Approach 2:
The patent extracts only the essential stabilizing function from high molecular weight polymers and surfactants, separating it from their harmful properties (high viscosity, low interfacial tension). The low molecular weight polymer with specific functional groups provides the necessary stabilization without the unwanted side effects.
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 surface modified pigment particles demonstrate excellent stability and rheological properties, maintaining particle size distribution and viscosity over time, making them suitable for long-term functioning in electronic devices without the drawbacks of previous methods.
Implementation Method 1
a surface functional group, such as a functional group Q, that can form a covalent bond or a hydrogen bond with a compound of Formula (1)
Implementation Method 2
a surface functional group, such as a functional group Q, that can form a covalent bond or a hydrogen bond with a compound of Formula (1)
Implementation Method 3
The compound of Formula (1) has the structure: where φ is a linear, branched or dendritic polymeric chain... Functional group Q can be bonded to the pigment particle surface via a covalent bond (chemisorption), an ionic bond, hydrogen bond or irreversible adsorption.
Data Source
AI summary
The present invention relates to surface modified carbon black pigment particles, comprising: a surface on the carbon black pigment particles containing a functional group Q; and a modifying compound M bonded to the surface via hydrogen bonds or via a covalent bond with the functional group Q to form the group -Q-M on the surface; wherein: the modifying compound M comprises a product formed by a full or partial hydrolysis of a compound of Formula (1): wherein: φ is a linear, branched or dendritic polymeric chain having a molecular weight from about 100 to about 5,000,000; L is -NR3C(O)NH-, -OC(O)NH-, -C(O)OCH2CH(OH)CH2-, -OCH2CH(OH)CH2-, -NHCH2CH(OH)CH2-, -alkylene-, -C(O)O-, -C(O)NR3-, -SO2NR3-, -SO2-, -NR3-, =N-, =N+-, -O- or -S-; each E independently is alkylene, arylene, alkylarylene, arylalkylene, alkyleneamino, alkyleneimino, alkyleneoxyalkylene, aryleneoxy, aryleneoxyalkylene, oxaalkylene, oxyalkylene, dioxyalkylene or oxyarylene; each R1 independently is H, hydroxyl, oxyalkyl, oxyalkylenearyl, halogen, acetate or amine; each R2 independently is alkyl, cycloalkyl, cycloheteroalkyl, aryl or alkylenearyl;R3 is H, alkyl, aryl or alkylaryl; m = 1 to 3; n = 0 to 2; m+n = 3; and x = 1 or 2.