Liquid Crystal Aligning Agent Barrier Layer
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Solution Overview
Problem
Existing liquid crystal alignment films suffer from high AC residual images and low contrast due to molecular migration between layers, which hinders alignment quality and surface flatness, limiting the inherent functions of materials.
Innovation Solution
A liquid crystal aligning agent comprising polyamic acids with photoreactive and liquid crystal groups, applied in a specific structure to enhance one-axis alignment and anchoring force, improving the separation and performance of upper and lower layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductive layer is disposed in the lower layer to release cumulated charges, then charge release function is improved, but conductive layer molecules migrate into the top layer, hindering alignment and reducing contrast
Solution Approach 1:
A barrier layer is introduced between the conductive lower layer and the light alignment upper layer. This barrier layer prevents conductive layer molecules from migrating into the alignment layer while allowing the conductive layer to maintain its charge release function. The barrier layer acts as an intermediary that blocks harmful molecular diffusion without interfering with the electrical functionality of the conductive layer.
Solution Approach 2:
The alignment film is segmented into three distinct layers: a conductive lower layer, a barrier intermediate layer, and a light alignment upper layer. This segmentation separates the conflicting functions into different spatial zones, allowing each layer to perform its specific function without interfering with others. The conductive layer handles charge release, the barrier layer prevents molecular migration, and the alignment layer provides optical alignment.
2Stability of the object's composition
If molecular weights and surface energy are adjusted to promote layer separation, then layer separation is improved, but surface flatness deteriorates, further affecting alignment quality
Solution Approach 1:
The barrier layer serves as an intermediary that provides a controlled interface between the conductive and alignment layers. Instead of relying on complex molecular weight and surface energy adjustments that compromise surface flatness, the barrier layer achieves layer separation through its inherent structural properties while maintaining a flat surface that supports high-quality alignment.
3Manufacturing precision
If liquid crystal component is added to improve alignment quality, then alignment quality is improved, but conductive layer molecules migrate and hinder alignment during annealing, causing AC residual image
Solution Approach 1:
The barrier layer acts as a protective intermediary that shields the liquid crystal components in the alignment layer from contamination by migrating conductive layer molecules. During annealing, the barrier layer prevents harmful molecular diffusion while allowing the liquid crystal components to anneal properly, thereby maintaining alignment quality and preventing AC residual image formation.
Solution Approach 2:
By segmenting the film into distinct layers with a barrier layer in between, the system separates the liquid crystal components from the conductive molecules. This spatial segmentation prevents harmful interactions during annealing, allowing each component to undergo its intended thermal processing without contamination that would cause AC residual image.
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 significantly enhances alignment quality, contrast, and surface flatness, reducing AC residual images and improving anisotropy in liquid crystal display devices.
Implementation Method 1
a polyamic acid having a photoreactive group
Implementation Method 2
a polyamic acid having a liquid crystal group... the liquid crystal part enhances the alignment thereof by heating
Implementation Method 3
The phase transfer of liquid crystal occurs in the mesogen part during the heating treatment for cyclization. Due to the intermolecular interactions of the liquid crystalline, a very strong one-axis alignment force is produced
Data Source
AI summary
The present application relates to a liquid crystal aligning agent, a liquid crystal alignment film and a method for producing the same, as well as a liquid crystal display device. The liquid crystal aligning agent comprises (i) a first polyamic acid having a photoreactive group without a liquid crystal group; (ii) a second polyamic acid having a liquid crystal group without a photoreactive group; (iii) a third polyamic acid having both a liquid crystal group and a photoreactive group; (iv) a fourth polyamic acid having neither a photoreactive group nor a liquid crystal group. The liquid crystal display device using the liquid crystal alignment film formed by the liquid crystal aligning agent provided by the present disclosure has a high display contrast and an improved AC residual image.