Liquid Crystal Aligning Agent Composition for Outdoor Reliability
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Solution Overview
Problem
Conventional liquid crystal display technologies face challenges in achieving excellent electrical characteristics and reliability, particularly in outdoor environments, due to issues with dust, electrostatic discharge, and the limitations of polyimide solubility and after-image generation in high-performance displays.
Innovation Solution
A liquid crystal aligning agent composition comprising a polymer with a polyamic acid repeating unit and a light stabilizer compound with a hindered amine-based functional group, which is applied to a substrate, dried, irradiated, and heat-treated to form a stable alignment film, reducing after-image and maintaining voltage holding ratio under heat and light exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rubbing method is used to align liquid crystals, then liquid crystal alignment is achieved, but fine dust and electrostatic discharge occur during manufacturing
Solution Approach 1:
The patent replaces the mechanical rubbing method with a photo-alignment method using light irradiation. The polymer film is coated on the substrate and then irradiated with polarized light to induce anisotropy and align liquid crystals, eliminating the need for physical contact and thus preventing dust generation and electrostatic discharge.
Solution Approach 2:
The patent changes the alignment mechanism from mechanical force (rubbing) to optical field interaction (light irradiation). By using polarized light with specific wavelength and intensity parameters, the polymer film achieves molecular orientation without mechanical contact, resolving the contradiction between alignment quality and harmful factor generation.
2Reliability
If polyimide is used for photo-alignment, then superior performance is achieved, but solubility in solvent is poor making direct application difficult
Solution Approach 1:
The patent applies a solubility-enhancing agent to the polymer film before light irradiation. This preliminary action modifies the film's properties to enable better solvent interaction during coating, allowing the polyimide-based composition to be applied in solution state and then cured to form the alignment film.
Solution Approach 2:
The patent introduces a solubility-enhancing agent as an intermediary substance that facilitates the coating process. This agent temporarily improves the solubility of polyimide in the coating solution, enabling uniform film formation, and is subsequently removed or integrated during heat treatment and light irradiation steps.
3Ease of operation
If conventional aligning agents are used, then basic alignment function is provided, but electrical characteristics and after-image performance are insufficient for high-performance displays
Solution Approach 1:
The patent uses a composite composition containing polyimide polymer, solubility-enhancing agent, and crosslinking agent. This composite material combines the alignment properties of polyimide with the solubility benefits of the enhancing agent and the stability of crosslinking, achieving both basic alignment function and superior electrical characteristics with reduced after-image effects.
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 provides a liquid crystal alignment film with improved electrical characteristics and reliability, maintaining high voltage holding ratios and reducing after-image generation even under prolonged exposure to heat and light, ensuring stable performance in outdoor conditions.
Implementation Method 1
it has been found that when a liquid crystal alignment film is made using a composition containing a polyamic acid and a light stabilizer compound having a hindered amine-based functional group, after-image generation is reduced and the film maintains superior voltage holding ratio characteristics even when exposed to light or heat for a long period of time
Implementation Method 2
the composition is coated on a substrate, dried, irradiated, and heat-treated to form a stable alignment film
Data Source
AI summary
Provided is a liquid crystal aligning agent composition comprising a hindered amine-based light stabilizer and a polyamic acid polymer derived from a diamine, a method for preparing a liquid crystal alignment film using the same, and a liquid crystal alignment film and a liquid crystal display using the same.