Composite Carbon Black Particles for LCD Optical Density
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Solution Overview
Problem
Current filler-polymer compositions for LCD components face challenges in achieving a balance between high electrical resistivity, optical density, thermal stability, and processability, particularly due to the limitations of carbon black loading and viscosity issues, which restrict the range of optical density adjustments and increase viscosity at high filler loadings.
Innovation Solution
Development of hybrid composite particles comprising carbon black aggregates coated with metal oxide or metalloid oxide, where the metal oxide or metalloid oxide covers at least 30% of the exposed surface area, allowing for improved electrical resistivity, optical density, and processability, and are produced through a specific multi-stage reactor process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If carbon black loading level is increased to increase optical density, then optical density is improved, but viscosity increases significantly
Solution Approach 1:
The patent uses composite particles consisting of carbon black cores coated with metal oxide or metalloid oxide shells. This composite structure allows the carbon black to provide optical density while the inorganic coating prevents excessive viscosity build-up and controls electrical conductivity, resolving the contradiction between optical density and viscosity.
Solution Approach 2:
The patent modifies the surface properties of carbon black by coating it with metal oxide or metalloid oxide, changing the particle surface area, surface chemistry, and inter-particle interactions. This parameter change allows higher carbon black loading levels to be achieved without the proportional increase in viscosity that would normally occur.
2Illumination intensity
If carbon black loading level is increased to increase optical density, then optical density is improved, but electrical resistivity decreases due to percolation
Solution Approach 1:
The inorganic metal oxide or metalloid oxide coating acts as a barrier between carbon black particles, disrupting the formation of continuous conductive paths (percolation networks). This allows the system to achieve high optical density through increased carbon black loading while maintaining high electrical resistivity by preventing electron transport between particles.
Solution Approach 2:
The metal oxide or metalloid oxide coating serves as an intermediary layer between carbon black particles. This intermediate layer electrically isolates the conductive carbon particles from each other, preventing percolation and maintaining high resistivity even at high filler loadings required for high optical density.
3Ease of operation
If high structure carbon black is used to improve dispersion ease, then dispersion is improved, but electrical conductivity increases
Solution Approach 1:
By coating carbon black aggregates with metal oxide or metalloid oxide, the patent creates composite particles that maintain the beneficial dispersion characteristics of high-structure carbon black while the inorganic coating interrupts electrical conductivity pathways, thus achieving good dispersion without excessive conductivity.
Solution Approach 2:
The patent applies local modification by coating only the surface of the carbon black aggregates with metal oxide or metalloid oxide. This local quality change allows the internal high-structure morphology to provide dispersion ease while the surface coating provides electrical isolation.
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 hybrid composite particles provide enhanced electrical resistivity, optical density, and thermal stability while maintaining low viscosity at high particle loadings, enabling more versatile and efficient use in LCD components and other displays.
Implementation Method 1
the at least one metal oxide or metalloid oxide is at least 30% by surface area of the exposed outer surface area of the composite particles... providing enhanced electrical resistivity
Implementation Method 2
Carbon blacks are used as pigments... increased loading level increases the optical density (OD), a measure of the opacity of a coating material
Implementation Method 3
The hybrid composite particles provide enhanced electrical resistivity, optical density, and thermal stability
Data Source
AI summary
Composite particles that super-aggregates of coated aggregates having low structure carbon black cores and metal/metalloid oxide mantles are described. Coatings containing filler-polymer compositions which have the composite particles as filler, such as curable coatings and cured coatings or films formed therefrom containing the filler-polymer compositions, with combinations of high resistivity, good optical density properties, good thermal stability, high dielectric constant, and good processability, along with their use in black matrices, black column spacers, light shielding elements in LCDs and other display devices, also are described. Inks containing the composite particle are described. Devices having these compositions, components and/or elements, and methods of preparing and making these various materials and products are described.