Liquid Crystal Alignment Agent Anchoring and Decomposition Control
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Solution Overview
Problem
Liquid crystal display elements, particularly in IPS and FFS modes, face issues with residual images due to weak anchoring ability and DC charge accumulation, as well as abnormal display phenomena like broken bright spots resulting from insufficient removal of photo-decomposition products during photodecomposition alignment treatment.
Innovation Solution
A liquid crystal alignment agent comprising a polyamic acid or polyimide solution, where the diamine compound includes a specific structure and is combined with a dianhydride compound, enhancing anchoring ability and facilitating the removal of photo-decomposition products, thereby improving alignment and charge dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoalignment treatment is used to improve alignment uniformity and eliminate surface defects, then alignment quality is improved, but anchoring capacity becomes weak causing residual images
Solution Approach 1:
The patent modifies the chemical composition parameters of the alignment agent by incorporating specific diamine compounds with hydroxyl or thiol groups. These compositional changes enable the material to maintain strong anchoring capacity while achieving uniform photoalignment, thus resolving the contradiction between alignment quality and anchoring strength.
Solution Approach 2:
The alignment agent is formulated as a composite material containing polyamic acid or polyimide combined with specific diamine compounds (having hydroxyl or thiol groups) and cyclic carboxylic acid anhydride compounds. This composite structure integrates the benefits of photoalignment uniformity with enhanced anchoring capacity, eliminating residual image issues while maintaining alignment precision.
2Manufacturing precision
If photodecomposition alignment treatment is used to achieve uniform alignment, then alignment quality is improved, but photo-decomposition products remain causing abnormal display phenomena
Solution Approach 1:
The patent converts the potentially harmful photo-decomposition process into a beneficial alignment mechanism. By using photodecomposition of the alignment agent itself (rather than decomposing a separate layer), the method achieves uniform alignment while the decomposition products are minimal and do not cause abnormal display phenomena.
Solution Approach 2:
The patent changes the chemical parameters of the alignment agent by incorporating specific diamine compounds with hydroxyl or thiol groups. These compositional modifications alter the photo-decomposition behavior to produce fewer harmful byproducts while maintaining effective alignment, thus eliminating abnormal display issues.
3Ease of operation
If rubbing alignment is used to achieve liquid crystal alignment, then alignment is achieved, but surface scratches, debris and static electricity problems occur
Solution Approach 1:
The patent replaces the mechanical rubbing process with a chemical/photo-based alignment method. The alignment agent is coated on the substrate and then activated by UV irradiation to achieve alignment without any mechanical contact. This substitution eliminates surface scratches, debris, and static electricity problems while maintaining alignment effectiveness.
Solution Approach 2:
The alignment agent serves as an intermediary substance between the substrate and the liquid crystal. Instead of directly rubbing the liquid crystal or substrate surface, the alignment agent mediates the alignment process through its molecular structure and photochemical properties, eliminating mechanical damage while achieving the desired alignment.
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 improves the anchoring ability of liquid crystals, quickly dissipates DC charges, and effectively removes photo-decomposition products, reducing residual images and abnormal display issues, making it suitable for high-quality IPS and FFS liquid crystal display elements.
Implementation Method 1
photodecomposition, photoisomerization and photocrosslinking. Due to its poor stability in the later stage of photoisomerization, photodecomposition and photocrosslinking are currently more popular
Data Source
AI summary
Provided are a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element. The liquid crystal alignment agent at least comprises one of a polyamic acid solution and a polyimide solution. The polyamic acid solution is obtained by means of a polymerization reaction of diamine compound component A and dianhydride compound component B in a solvent, and the polyimide solution is obtained from the polyamic acid solution via a dehydration imidization treatment. The diamine component A at least comprises one of the diamine compounds represented by “formula 1”. The obtained liquid crystal alignment agent has a better liquid crystal alignment capability, an excellent effect on image sticking, and the effect that decomposition products resulting from light alignment are easy to remove.