Polyimide Alignment Film Hardness via Catalyst-Free Crosslinking
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Solution Overview
Problem
Traditional alignment films in TFT-LCDs face challenges in increasing hardness due to the volatility of crosslinking agents and catalysts, leading to defects and inadequate hardness enhancement.
Innovation Solution
The use of a polyimide-based alignment film material with a crosslinked polymer formed from phthalonitrile-containing monomers and benzimidazole-containing compounds, which undergoes a crosslinking reaction without the need for additional catalysts, enhancing crosslink density and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional crosslinking agents or catalysts are added to increase crosslink density, then the hardness of the alignment film is improved, but the crosslinking agent or catalyst is volatilized during thermal curing, causing defects and reducing manufacturing precision
Solution Approach 1:
The patent extracts and eliminates the harmful small molecular crosslinking agents and catalysts from the alignment film material system. Instead of adding external crosslinking agents or catalysts that cause volatility and defects, the invention uses phthalonitrile-containing monomers that undergo self-crosslinking through thermal curing, removing the source of the problem while maintaining the crosslinking function.
Solution Approach 2:
The patent changes the chemical parameters of the crosslinking system by using phthalonitrile-containing monomers with specific functional groups that enable self-crosslinking through nitrile group reactions. This parameter change allows the system to achieve crosslinking without external agents, preventing volatility and defect formation while maintaining hardness improvement.
2Strength
If crosslinking agents are added to increase crosslink density, then the hardness of the alignment film is improved, but the alignment film becomes more complex in composition, reducing ease of manufacture
Solution Approach 1:
The patent removes the need for separate crosslinking agents and catalysts from the material composition. The alignment film material consists solely of phthalonitrile-containing monomers that perform both the polymer formation and crosslinking functions, simplifying the material system while achieving the desired hardness improvement through self-crosslinking.
3Ease of manufacture
If traditional alignment film materials are used, then the manufacturing process is simple, but the alignment film is soft and susceptible to damage from touching and pressing operations
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating phthalonitrile-containing monomers that undergo thermal crosslinking to form a highly crosslinked network structure. This parameter change transforms the alignment film from a soft, uncrosslinked structure to a hard, crosslinked structure while maintaining manufacturing simplicity through a single-step thermal curing process.
Solution Approach 2:
The patent creates a composite material system where the phthalonitrile-containing monomers form a crosslinked polymer network within the polyimide matrix. This composite structure combines the beneficial properties of both the polyimide base material and the crosslinked network, achieving enhanced hardness while maintaining the simplicity of processing the original material system.
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
This approach effectively increases the crosslink density and hardness of the alignment film without the use of additional catalysts, improving the film's resistance to touch and pressure without forming defects.
Implementation Method 1
crosslinked polymer formed from a first component through a crosslinking reaction
Implementation Method 2
thermally curing the polyamide acid to undergo a ring-closure reaction
Implementation Method 3
polyamide acid to undergo a ring-closure reaction
Data Source
AI summary
An alignment film material and a method of producing an alignment film are described. The alignment film material has polyimide and crosslinked polymer. The crosslinked polymer is formed from a first component through a crosslinking reaction. A crosslink density of the alignment film can be enhanced without additionally adding a catalyst, so as to increase a hardness of the alignment film.