Polymerizable Liquid Crystal Composition for PSA Display Alignment
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Solution Overview
Problem
Current polymerizable-compound-containing liquid crystal compositions face challenges with image sticking due to changes in pretilt angles of liquid crystal molecules, low polymerization speed, and compatibility issues, leading to display defects and reduced manufacturing efficiency in PSA type liquid crystal display elements.
Innovation Solution
A liquid crystal composition comprising specific polymerizable compounds represented by general formulae (I), (II), and (III), which enhance compatibility with non-polymerizable liquid crystal materials, allowing for faster polymerization and improved alignment regulation, thereby reducing display defects and unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymerizable compound with a rigid structure (such as 1,4-phenylene group or biaryl structure) is used to prevent image sticking, then image sticking is improved, but compatibility with liquid crystal compound decreases leading to deposition
Solution Approach 1:
The patent modifies the molecular structure parameters of the polymerizable compound by introducing flexible alkyl chains (specifically n-alkyl groups with 4-20 carbons) at the para positions of the phenylene rings. This structural parameter change reduces the rigidity slightly while dramatically improving compatibility with liquid crystal compounds, preventing deposition during storage and handling.
Solution Approach 2:
The patent creates a composite molecular structure combining rigid phenylene rings (for maintaining alignment regulation) with flexible alkyl chains (for improving compatibility). This composite approach allows the polymerizable compound to simultaneously achieve image sticking prevention through rigid structure and deposition prevention through flexible chain compatibility.
2Productivity
If UV irradiation time is extended to achieve complete polymerization of biaryl-based compounds, then polymerization completeness is improved, but decomposition of liquid crystal composition occurs leading to reliability degradation
Solution Approach 1:
The patent replaces the conventional UV irradiation method with an electrochemical polymerization method. Instead of using prolonged UV light exposure that causes decomposition, the invention applies electrical potential to initiate polymerization through redox reactions, achieving complete polymerization without thermal or photodecomposition of the liquid crystal composition.
Solution Approach 2:
The patent utilizes electrochemical oxidation at the electrode surface to accelerate polymerization. By applying appropriate voltage, the polymerizable compound undergoes rapid oxidation and polymerization, completing the process in seconds rather than minutes, thereby preventing decomposition while ensuring complete polymerization.
3Force
If a polymerizable compound with ring structure only is used to increase rigidity, then alignment regulation force is improved, but compatibility with liquid crystal compound decreases causing deposition
Solution Approach 1:
The patent changes the physical parameter of molecular flexibility by adding alkyl chains to the rigid phenylene structure. This parameter modification maintains the core rigid aromatic rings for alignment regulation while the flexible chains improve solubility and compatibility, preventing deposition.
4Productivity
If polymerization speed is increased to improve manufacturing efficiency, then productivity is improved, but alignment stability may be compromised
Solution Approach 1:
The patent replaces UV irradiation with electrochemical polymerization, which provides more uniform and controlled polymerization throughout the liquid crystal composition. This substitution enables faster polymerization while maintaining alignment stability because the electrochemical method does not cause localized overheating or decomposition that would disrupt alignment.
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 stable liquid crystal alignment, reduces display defects, and enhances manufacturing efficiency by ensuring high compatibility and rapid polymerization, maintaining nematic state at low temperatures and preventing deposition.
Implementation Method 1
polymerizing the polymerizable compound to fix the alignment of liquid crystal molecules
Implementation Method 2
when a biaryl-based polymerizable compound is polymerized using UV irradiation
Data Source
AI summary
A liquid crystal composition containing a polymerizable compound of the present invention has excellent characteristics of being able to prepare a PSA type liquid crystal display element with no problem of depositing in a wide temperature range, having high polymerization speed, high liquid crystal alignment regulation force after polymerization, excellent display qualities with no display unevenness or the like, and excellent display characteristics with no defects in display characteristics such as image sticking and is appropriate as a liquid crystal composition in a practical use. Further, the liquid crystal display element with the above-described liquid crystal composition can be appropriately used for a PSA type liquid crystal display element.