Liquid Crystal Aligning Agent with Cyclobutane Ring for Heat Resistance
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Solution Overview
Problem
Liquid crystal alignment films obtained by photo-alignment methods have insufficient alignment regulating power, leading to AC afterimages and inferior heat resistance, particularly when exposed to high temperatures over time.
Innovation Solution
A liquid crystal aligning agent containing a polymer with specific partial structures, including a cyclobutane ring and nitrogen-containing heterocyclic groups, is used to form a liquid crystal alignment film through a photo-alignment process, enhancing alignment order and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid crystal alignment film is obtained by photo-alignment treatment using a liquid crystal aligning agent containing a polyimide polymer having a cyclobutane ring structure in the main chain, then it is possible to prevent the generation of static electricity and dust and to impart uniform liquid crystal alignment properties, but micro bright spots are likely to occur when the obtained liquid crystal element is exposed under a high temperature environment for a long time
Solution Approach 1:
The patent modifies the chemical structure of the polyimide polymer by introducing specific substituent groups ( Formula (4) with nitrogen-containing heterocyclic groups) to change the thermal stability parameters of the material. This structural modification prevents the formation of micro bright spots at high temperatures while maintaining the photo-alignment properties, thus resolving the contradiction between heat resistance and micro bright spot formation.
Solution Approach 2:
The patent creates a composite structure by combining the cyclobutane ring-containing polyimide backbone with specific diamine compounds having nitrogen-containing heterocyclic groups (pyridine, pyrimidine, etc.). This composite molecular structure provides both the photo-alignment functionality and the thermal stability needed to prevent micro bright spots under high temperature conditions.
2Ease of manufacture
If a liquid crystal alignment film is obtained by photo-alignment treatment, then it is possible to prevent the generation of static electricity and dust, but the alignment regulating power of liquid crystal molecules is not sufficient compared to a rubbing treatment
Solution Approach 1:
The patent enhances the alignment regulating power by modifying the molecular structure of the aligning agent to include specific nitrogen-containing heterocyclic groups that increase the photo-reactivity and alignment efficiency. This allows the photo-alignment process to achieve rubbing-like alignment quality while maintaining the manufacturing advantages of the photo-alignment method.
3Manufacturing precision
If a liquid crystal alignment film is obtained by photo-alignment treatment, then it is possible to precisely control a liquid crystal alignment direction, but burn-in called AC afterimage is likely to occur
Solution Approach 1:
The patent introduces specific structural units ( Formula (4) with nitrogen-containing heterocyclic groups) that improve the photostability and reduce molecular degradation during operation. This prevents the AC afterimage phenomenon while preserving the precise alignment direction control achieved through photo-alignment treatment.
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 achieves excellent AC afterimage characteristics and long-term heat resistance in liquid crystal elements, reducing micro bright spots and improving photoreactivity and alignment properties.
Implementation Method 1
a photo-alignment process in which a coating film is formed using the liquid crystal aligning agent, and light is emitted to the coating film to impart a liquid crystal alignment ability
Data Source
AI summary
According to the present invention, a liquid crystal aligning agent is configured to contain a polymer (P) which has at least one partial structure selected from the group consisting of a partial structure represented by formula (1) and a partial structure represented by formula (2). In formula (1) and formula (2), X1 represents a tetravalent organic group that has a cyclobutane ring structure, while having at least one substituent in the ring portion of the cyclobutane ring; X2 represents a divalent organic group of a specific structure which has an aliphatic structure and a divalent nitrogen-containing heterocyclic group; and each of R5 and R6 independently represents a hydrogen atom or a monovalent organic group having 1-6 carbon atoms.