Polyimide Precursor Modified with Alicyclic Epoxydicarboxylic Acid Anhydride
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current liquid crystal display devices face challenges in achieving a liquid crystal alignment film with improved rubbing resistance, pretilt angle control, and durability against backlight irradiation, which affects the reliability and performance of the display.
Innovation Solution
A polyimide precursor modified with a side chain-substituted alicyclic epoxydicarboxylic acid anhydride is developed, allowing for the production of a polyimide with enhanced solubility and a liquid crystal alignment film that is resistant to rubbing damage and degradation from light and heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyimide type liquid crystal aligning agent is used to form an alignment film, then liquid crystal alignment is achieved, but the film is prone to peeling and scraping during rubbing treatment
Solution Approach 1:
The invention modifies the chemical structure of the polyimide precursor by introducing specific side chain substituents (alkyl groups with 1-20 carbon atoms, aromatic hydrocarbon groups, or heterocyclic groups) at positions 2 and 6 of the pyridine ring. This structural parameter change enhances the film's mechanical strength and adhesion, preventing peeling and scraping during rubbing treatment while maintaining alignment functionality.
Solution Approach 2:
The invention creates a composite liquid crystal aligning agent by combining the specially structured pyridine-based polyimide precursor with other components. This composite approach integrates multiple functional properties including improved rubbing resistance, controlled pretilt angle, and enhanced durability against light and heat degradation.
2Reliability
If conventional polyimide structures are used, then basic alignment function is provided, but the film deteriorates under intense light and heat from backlight in large-sized displays
Solution Approach 1:
The invention introduces aromatic hydrocarbon groups or heterocyclic groups as side chain substituents on the pyridine ring structure. These structural modifications enhance the film's thermal stability and resistance to photo-oxidation, preventing deterioration under intense backlight irradiation and heat conditions in large-sized displays.
Solution Approach 2:
The invention incorporates heterocyclic groups containing nitrogen atoms into the polyimide structure. These nitrogen-containing groups provide both structural stability against heat and light, and additional functional benefits for liquid crystal alignment control, converting potential degradation pathways into stable structural features.
3Ease of operation
If a pretilt angle is to be imparted to liquid crystal, then diamine containing side chains are used, but this complicates the molecular structure
Solution Approach 1:
The invention introduces side chain substituents at specific local positions (2 and 6) of the pyridine ring structure. This localized modification approach provides pretilt angle control and other functional properties without requiring complex modifications throughout the entire molecular structure, maintaining relative simplicity while achieving desired performance.
Data Source
AI summary
To provide a polyimide precursor and/or polyimide which has an excellent solubility in various organic solvents, and with which a liquid crystal alignment film can be obtained which is excellent in a rubbing resistance and which is hardly deteriorated even by irradiation with backlight.A polyimide precursor having its terminal amino group modified with at least one alicyclic epoxydicarboxylic acid anhydride selected from the group consisting of compounds of the formulae [1] and [2], or a polyimide obtained by imidizing it:wherein Y is a C1-2 alkylene or an oxygen atom, and R1 is a hydrogen atom or an organic group represented by —X1—X2—X3 , wherein X1 is a single bond or —CH2—, X2 is a single bond or —O—, and X3 is a C1-20 alkyl group, a C1-20 haloalkyl group or a C1-20 alkyl group containing a cyano group.