Liquid Crystal Photo Alignment Agent Solvent Optimization
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Solution Overview
Problem
Liquid crystal displays face challenges in achieving uniform alignment and reliability due to limitations in the rubbing method, such as foreign substance generation and non-uniformity, which are not adequately addressed by existing photo alignment methods.
Innovation Solution
A liquid crystal photo alignment agent with a specific composition ratio of polyimide polymer, cyclobutane dianhydride, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether is used, optimizing the solvent composition to improve coating properties and residual image characteristics through heat treatment and polarized ultraviolet light exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rubbing method is used to align liquid crystal molecules, then alignment in a certain direction is achieved, but foreign substances are generated and uniformity of alignment is poor
Solution Approach 1:
The patent replaces the mechanical rubbing method with a photo alignment method using polarized light irradiation on a photofunctional polymer layer. This substitution eliminates the need for physical contact that causes foreign substance generation and achieves more uniform alignment through optical field control rather than mechanical friction.
Solution Approach 2:
The patent optimizes the composition ratios of solids (2-10 wt%), first solvent (50-80 wt%), and second solvent (15-40 wt%) to control the coating properties and performance of the photo alignment layer. By adjusting these parameters, the patent achieves both good coating uniformity and effective photo alignment functionality.
2Ease of manufacture
If a liquid crystal photo alignment agent is applied to improve coating property, then printability is enhanced, but residual image characteristics may deteriorate
Solution Approach 1:
The patent optimizes the composition ratios of solids (2-10 wt%), first solvent (50-80 wt%), and second solvent (15-40 wt%) to simultaneously achieve good coating properties and residual image characteristics. This parameter optimization allows the photo alignment layer to be properly formed during coating while maintaining its photofunctionality for effective liquid crystal alignment and residual image prevention.
Solution Approach 2:
The patent uses a composite solvent system comprising a first solvent (NMP, NEP, DMF, GVL, or PC) and a second solvent (PGB, DPM, PGnPE, DEGDE, or DA), combined with photofunctional solids. This composite material approach allows the solvent mixture to provide both excellent coating/printability and maintained photofunctionality after drying, resolving the contradiction between ease of manufacture and reliability.
3Ease of manufacture
If the composition ratio of solids and solvents is not optimized, then coating property deteriorates, but residual image limitation increases
Solution Approach 1:
The patent establishes specific composition ratio ranges: solids (2-10 wt%), first solvent (50-80 wt%), and second solvent (15-40 wt%). These optimized parameters ensure proper coating properties including uniformity and adhesion, while simultaneously maintaining the photofunctionality needed to prevent residual images. The balanced composition allows both coating performance and display reliability to be achieved together.
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 optimized solvent composition enhances the alignment layer's coating properties and solubility, reducing residual image issues by improving the alignment and mobility of liquid crystal molecules, thereby enhancing the reliability of liquid crystal displays.
Implementation Method 1
reactions such as photoisomerization, photocrosslinking, and photodegradation anisotropically occur due to polarized light irradiation
Implementation Method 2
reactions such as photoisomerization, photocrosslinking, and photodegradation anisotropically occur due to polarized light irradiation
Implementation Method 3
reactions such as photoisomerization, photocrosslinking, and photodegradation anisotropically occur due to polarized light irradiation
Implementation Method 4
subjecting the first preliminary alignment layer to a first heat treatment to form a first heat treated first preliminary alignment layer
Data Source
AI summary
Provided is a liquid crystal photo alignment agent including: a solid including at least one of a polyimide polymer, cyclobutane dianhydride (CBDA) or diamine; a first solvent including at least one of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl formamide, γ-butyrolacton or propylene carbonate; and a second solvent including at least one of propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, propylene glycol n-propyl ether, diethylene glycol diethyl ether or diacetone alcohol, wherein the first solvent is included in an amount of about 50 wt % to about 80 wt % based on the total weight of the liquid crystal photo alignment agent; and the second solvent is included in an amount of about 15 wt % to about 40 wt % based on the total weight of the liquid crystal photo alignment agent. Also provided is a method of manufacturing a liquid crystal display including the liquid crystal photo alignment agent.