Polymerizable Compound for Liquid Crystal Display Response Speed
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Solution Overview
Problem
Liquid crystal display elements face challenges with narrow viewing angles, slow response speed, and decreased voltage holding ratios due to low polymerization reactivity and solubility issues of polymerizable compounds, particularly in PSA-VA type displays.
Innovation Solution
A liquid crystal composition incorporating a polymerizable compound with a (meth)acryloyl group, represented by a specific general formula, is used to enhance the polymerization reactivity and solubility, allowing for improved orientation stability and voltage holding ratios when irradiated with energy radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a polymerizable compound is added to liquid crystal composition to improve response speed, then response speed is improved, but voltage holding ratio decreases due to polymer movement
Solution Approach 1:
The patent uses a composite material system consisting of polymerizable compound (for fast response), liquid crystal molecules (for display function), and crosslinking agent (for stability). The crosslinking agent forms a three-dimensional network structure that anchors the polymerizable compound, preventing polymer movement while maintaining fast response characteristics. This composite approach resolves the contradiction between speed improvement and voltage holding ratio maintenance.
Solution Approach 2:
The crosslinking agent is introduced into the liquid crystal composition before the polymerizable compound undergoes polymerization. This preliminary action creates a stable network structure in advance that will constrain the polymer chains during subsequent polymerization, preventing excessive movement and maintaining voltage holding ratio while still allowing fast response speed.
2Speed
If polymerizable compound with high polymerization reactivity is used to improve response speed, then response speed is improved, but solubility in liquid crystal composition decreases
Solution Approach 1:
The patent modifies the molecular structure parameters of the polymerizable compound by introducing specific functional groups and adjusting molecular weight. These parameter changes enable the compound to achieve both high polymerization reactivity (for fast response) and adequate solubility in the liquid crystal composition. The structural optimization allows the compound to dissolve properly before polymerization while maintaining high reactivity upon irradiation.
3Stability of the object's composition
If energy radiation is applied to polymerize the composition to improve orientation stability, then orientation stability is improved, but voltage holding ratio decreases due to compound deterioration
Solution Approach 1:
The patent replaces the conventional approach of using strong energy radiation (which causes deterioration) with a mild crosslinking mechanism. The crosslinking agent forms a stable three-dimensional network structure through gentle crosslinking reactions, achieving orientation stability without requiring intense energy radiation that would deteriorate the liquid crystal compounds. This substitution of the polymerization mechanism resolves the contradiction between orientation stability and voltage holding ratio.
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 enables liquid crystal display elements with enhanced response speed and reliability, maintaining voltage holding ratios even after energy irradiation, and preventing polymer movement within the liquid crystal composition.
Implementation Method 1
the polymerizable component is polymerized by light or heat
Data Source
AI summary
Disclosed is a liquid crystal composition formed by including a polymerizable compound represented by general formula (I) in a nematic liquid crystal composition with negative dielectric anisotropy (Δ∈). In the formula, ring C1 represents a benzene-1,2,4-triyl group, or the like; rings C2 to C4 represent a 1,4-phenylene group, a naphthalene-2,6-diyl group, or the like; M1 to M3 represent a hydrogen atom or a methyl group; Z1 and Z2 are a direct coupling, -L1-, -L1O—, -L1O—CO—, or the like; Z6 is a direct coupling, -L2-, -OL2-, —O—COL2-, or the like; at least one of Z1, Z2, and Z6 is not a direct coupling; L1 and L2 represent a C1-10 alkylene group; Z3 to Z5 represent a direct coupling, an ester bond, or the like; and p, q, and r are 0 or 1, wherein 1≦p+q+r≦3.