Liquid Crystal Composition for Fast Response and Low-Temperature Stability
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Solution Overview
Problem
The existing liquid crystal compositions used in liquid crystal display elements face challenges such as low temperature stability, susceptibility to smectic phase transition, and display defects like dropping marks and burn-in, especially in large-sized displays and smartphones, due to the addition of nonpolar liquid crystal compounds for viscosity reduction, which affect compatibility and operational stability.
Innovation Solution
A liquid crystal composition with a positive dielectric anisotropy, comprising specific compounds represented by General Formulas (Ia) and (Ib) in a 85% to 95% mass ratio, combined with compounds represented by General Formula (M), ensuring high speed response, low viscosity, and stability across a wide temperature range, while maintaining low rotational viscosity and high specific resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large amount of nonpolar liquid crystal compound is added to reduce viscosity, then rotational viscosity decreases and high speed response is achieved, but low temperature stability deteriorates due to precipitation and smectic phase transition
Solution Approach 1:
The patent changes the chemical structure parameters of the liquid crystal compounds by introducing specific polar groups (cyano, fluoro, or chloro) and controlling the ratio of polar to nonpolar compounds. This parameter change allows achieving low viscosity (high response speed) while maintaining low temperature stability through the stabilizing effect of polar groups.
Solution Approach 2:
The patent creates a composite liquid crystal composition by combining polar liquid crystal compounds (with cyano, fluoro, or chloro groups) and nonpolar liquid crystal compounds in specific ratios (5-50 mass% polar, 50-95 mass% nonpolar). This composite structure allows the polar compounds to provide stability while nonpolar compounds provide low viscosity, resolving the contradiction between response speed and low temperature stability.
2Speed
If nonpolar liquid crystal compounds are added for viscosity reduction, then rotational viscosity decreases, but compatibility deteriorates leading to precipitation at low temperatures
Solution Approach 1:
The patent creates a composite liquid crystal composition by combining polar liquid crystal compounds (with cyano, fluoro, or chloro groups) and nonpolar liquid crystal compounds in specific ratios (5-50 mass% polar, 50-95 mass% nonpolar). This composite structure allows the polar compounds to provide stability while nonpolar compounds provide low viscosity, resolving the contradiction between response speed and low temperature stability.
Solution Approach 2:
The patent changes the chemical structure parameters of the liquid crystal compounds by introducing specific polar groups (cyano, fluoro, or chloro) and controlling the ratio of polar to nonpolar compounds. This parameter change allows achieving low viscosity (high response speed) while maintaining low temperature stability through the stabilizing effect of polar groups.
3Reliability
If liquid crystal compounds with positive Δε are used for horizontal alignment displays, then dielectric anisotropy is improved, but viscosity increases reducing response speed
Solution Approach 1:
The patent creates a composite liquid crystal composition by combining polar liquid crystal compounds (with cyano, fluoro, or chloro groups) and nonpolar liquid crystal compounds in specific ratios (5-50 mass% polar, 50-95 mass% nonpolar). This composite structure allows the polar compounds to provide stability while nonpolar compounds provide low viscosity, resolving the contradiction between response speed and low temperature stability.
Solution Approach 2:
The patent applies local quality by having different compound types perform different functions: polar compounds (with cyano, fluoro, or chloro groups) provide high dielectric anisotropy and stability, while nonpolar compounds provide low viscosity. This functional differentiation within the composition allows simultaneous optimization of dielectric anisotropy and response speed.
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 composition achieves high speed response performance, improved low-temperature solubility, and enhanced stability against heat and light, reducing display defects and increasing yield in manufacturing, particularly suitable for IPS and TN-type liquid crystal display elements.
Implementation Method 1
a liquid crystal composition having positive dielectric anisotropy (Δε) and high speed response
Implementation Method 2
a liquid crystal composition having positive dielectric anisotropy (Δε) and high speed response
Data Source
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Figure 3
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AI summary
An object of the present invention is to provide a liquid crystal display element using a liquid crystal composition in which various characteristics of the liquid crystal display element such as dielectric anisotropy, viscosity, a nematic phase upper limit temperature, nematic phase stability at a low temperature, and γ1, and a burn-in characteristic of the display element are not deteriorated. The present invention provides a liquid crystal composition having excellent low temperature stability while maintaining a high speed response of the liquid crystal composition by using a liquid crystal composition containing a compound represented by General Formula (A) and a compound represented by General Formula (M), and a liquid crystal display element including the composition.