Transparent Polyimide Composition for LTPS Heat and Yellowing Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyimides do not meet the high heat resistance requirements for LTPS TFT processing, leading to yellowing and adverse effects on optical properties during high-temperature processes, limiting their suitability as glass substitutes in flexible and transparent displays.
Innovation Solution
A polyimide formulation with specific repeating units derived from TCA, diamines with cardo, benzene ring, biphenyl, phenylbenzimidazole, or phenylbenzoxazole structures, and ether or ester groups, optimized to maintain good heat resistance and optical properties through controlled molar fractions and molecular weights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If existing polyimide is used to replace glass substrate, then lightness, thinness, and flexibility are improved, but heat resistance deteriorates during high-temperature LTPS TFT processing
Solution Approach 1:
The patent modifies the chemical structure parameters of polyimide by introducing specific repeating units (cardo structure, benzene ring, biphenyl, phenylbenzimidazole, phenylbenzoxazole, ether group, ester group) to change the thermal stability parameter, achieving both lightness and high heat resistance (Tg > 300°C) simultaneously
Solution Approach 2:
The patent creates a composite polyimide structure combining multiple functional repeating units with different properties - cardo structure for thermal stability, aromatic groups for rigidity and heat resistance, and ether/ester groups for flexibility - achieving a balance between weight reduction and heat resistance
2Ease of operation
If transparent polyimide is used for high-temperature processing, then flexibility is improved, but optical properties deteriorate due to yellowing
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific diamine structures (cardo, benzene ring, biphenyl, phenylbenzimidazole, phenylbenzoxazole) that resist yellowing at high temperatures, maintaining both flexibility and optical stability (low yellow index) simultaneously
Solution Approach 2:
The patent converts the potential harmful effect of high-temperature processing into a beneficial outcome by using heat-resistant repeating units that maintain optical properties even after exposure to temperatures above 300°C, preventing yellowing rather than reacting to it
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 resulting polyimide exhibits excellent heat resistance, maintaining good optical properties after high-temperature processing, with Tg > 300°C, high total light transmittance, low yellow index, and low haze, making it suitable for replacing glass in electronic displays.
Implementation Method 1
performing an imidization of the polyamic acid described above to form a polyimide
Data Source
AI summary
A polyimide is provided, which contains at least one repeating unit selected from a group consisting of the following general formulas, M, N, and O):X is a residue derived from TCA represented by formula I. Y1 is a residue derived from a diamine with a cardo structure. Y2 is a residue derived from a diamine with the structure of a benzene ring, biphenyl, phenylbenzimidazole or phenylbenzoxazole. Y3 is a residue derived from a diamine with an ether or an ester group.