Liquid Crystal Aligning Agent Composition for Photo-Alignment
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Solution Overview
Problem
Existing liquid crystal alignment methods, such as the rubbing method and photo-alignment using polyimide, face challenges with high energy requirements, process costs, and limitations in productivity and stability, particularly in achieving uniform alignment and high imidization rates.
Innovation Solution
A liquid crystal aligning agent composition comprising specific polymers with imide repeating units, epoxy compounds, and amine compounds with functional groups, allowing for direct light irradiation without high-temperature heat treatment, enhancing alignment stability and film strength while improving imidization rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rubbing method is used to align liquid crystals, then liquid crystal alignment can be achieved, but fine dust or electrostatic discharge (ESD) may occur during manufacture
Solution Approach 1:
The patent replaces the mechanical rubbing method with a photo-alignment method using a specific polyimide composition. The alignment is achieved through light irradiation that induces anisotropy in the polymer film, eliminating the need for physical contact with fibers that generate dust and static electricity. This substitution of mechanical action with optical action directly resolves the harmful factors while maintaining alignment functionality.
2Reliability
If polyimide is used for photo-alignment, then liquid crystal alignment properties are improved, but large amounts of light irradiation energy are required and additional heat treatment is needed
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyimide by incorporating specific repeating units (Formulas 1-4) with particular molecular structures and ratios. This compositional parameter change enables the material to achieve adequate alignment properties with reduced light energy and eliminate the need for additional heat treatment, as the modified polyimide structure responds more efficiently to light irradiation.
Solution Approach 2:
The patent creates a composite polyimide material combining multiple types of repeating units (Formulas 1-4) with different functional characteristics. This composite structure integrates the advantages of each unit type, achieving enhanced alignment efficiency that reduces both light energy requirements and the need for subsequent heat treatment processes.
3Reliability
If conventional polyimide is used for photo-alignment, then alignment can be achieved, but productivity is reduced due to high energy requirements and additional processing steps
Solution Approach 1:
The patent extracts and eliminates the unnecessary additional heat treatment step from the conventional photo-alignment process. The modified polyimide composition achieves both alignment and stabilization in a single light irradiation step, removing the separate heat treatment process that prolongs manufacturing cycle time and reduces productivity.
4Ease of manufacture
If polyamic acid or polyamic acid ester is used as precursor, then solubility is improved for solution coating, but high-temperature heat treatment is required to form polyimide
Solution Approach 1:
The patent performs preliminary structural modification of the polyimide molecule during the synthesis stage, incorporating repeating units that pre-establish the desired alignment properties. This preliminary action eliminates the need for subsequent high-temperature heat treatment to induce anisotropy, as the alignment capability is built into the molecular structure before coating.
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 solution enables the production of liquid crystal alignment films with improved alignment properties, stability, and voltage holding ratios, reducing energy consumption and process time, and enhancing storage stability, making it suitable for mass production.
Implementation Method 1
a liquid crystal aligning agent composition which includes a first polymer for a liquid crystal aligning agent, a second polymer for a liquid crystal aligning agent, a compound having two or more epoxy groups in a molecule, and a compound in which at least one hydrogen atom bonded to a nitrogen atom contained in a primary amine or a secondary amine is substituted with at least one functional group selected from the group consisting of a tert-butoxycarbonyl group, a 9-fluorenylmethoxycarbonyl group, and a carboxybenzyl group
Implementation Method 2
a photo-alignment method of inducing anisotropy in a polymer film by light irradiation rather than the rubbing, and aligning liquid crystals using the anisotropy
Data Source
AI summary
The present invention provides a liquid crystal aligning agent composition that has excellent storage stability, can secure a high imidization rate, and can produce a liquid crystal alignment film having improved film strength together with liquid crystal alignment properties, a method for producing a liquid crystal alignment film using the same, and a liquid crystal alignment film and a liquid crystal display device using the same.