Self-Cleaving Monomers for PSA Layer Formation
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Solution Overview
Problem
The existing methods for forming polymer sustained alignment (PSA) layers in liquid crystal display devices face challenges such as display unevenness and increased takt time, which affect the quality and reliability of the liquid crystal display panels, particularly due to issues with polymerization initiators and light exposure.
Innovation Solution
A liquid crystal composition that includes radical polymerizable monomers with self-cleaving photopolymerization initiators, which generate radicals upon exposure to light, allowing for efficient polymerization without additional initiators and reducing impurities, thereby shortening takt time and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photopolymerization initiators are used to form PSA layers, then polymerization can be initiated, but display unevenness occurs and takt time increases
Solution Approach 1:
The patent extracts and eliminates the conventional photopolymerization initiator from the system. Instead of using separate initiators like Irgacure 651, the invention employs monomers that inherently possess photopolymerization-initiating functionality through their molecular structure (e.g., benzophenone groups), thereby removing the source of display unevenness and reducing takt time without requiring additional initiator components
Solution Approach 2:
The patent merges the functions of the photopolymerization initiator and the monomer into a single component. The monomer molecules contain both the polymerizable double bond and the photopolymerization-initiating group (such as benzophenone), combining what were previously separate substances into one integrated molecule that performs both functions simultaneously
2Productivity
If additional photopolymerization initiators are added to speed up polymerization, then takt time decreases, but display unevenness and impurities increase
Solution Approach 1:
The monomers in the patent are designed to be self-sufficient by containing built-in photopolymerization-initiating groups. When exposed to UV light, these monomers automatically initiate polymerization of themselves and other monomers without requiring external initiators, achieving fast polymerization speed while maintaining display quality through the absence of additional impurity-generating components
3Reliability
If long-time ultraviolet light irradiation is used to polymerize monomers, then polymerization occurs without additional initiators, but component deterioration increases
Solution Approach 1:
The patent modifies the molecular parameters of the monomers by incorporating photopolymerization-initiating groups with specific absorption characteristics. These groups are designed to absorb UV light efficiently at particular wavelengths and convert it into radical species that initiate polymerization, thereby reducing the total light exposure time required compared to systems without such optimized parametric design
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
This approach significantly reduces takt time, maintains high display quality, and enhances the reliability of liquid crystal display devices by minimizing voltage holding ratio reduction and preventing component deterioration from prolonged light exposure.
Implementation Method 1
at least one kind of the radical polymerizable monomers being a compound generating radicals through a self-cleavage reaction by exposure to light
Implementation Method 2
the components such as monomers are polymerized by irradiation with heat or light (ultraviolet light)
Implementation Method 3
a liquid crystal composition for forming a polymer layer capable of controlling the alignment of liquid crystals
Implementation Method 4
liquid crystal molecules having birefringence
Data Source
AI summary
Several aspects of the present invention provide a liquid crystal composition capable of shortening the takt time and achieving excellent display qualities, and a liquid crystal display device and a method for producing a liquid crystal display device which use the liquid crystal composition. The liquid crystal composition of several aspects of the present invention includes a liquid crystal material and one or more kinds of radical polymerizable monomers, at least one kind of the radical polymerizable monomers being a compound generating radicals through a self-cleavage reaction by exposure to light and having at least two radical polymerizable groups.