Polyamide-imide Copolymer Film for Flexible Display Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyimide films used in flexible displays have a high yellow index and double refraction, which reduces light transmission and contrast, failing to meet market requirements for flexible displays.
Innovation Solution
A polyamide-imide copolymer film is developed by copolymerizing aromatic dianhydride and aromatic dicarbonyl compounds, including fluorinated and non-fluorinated aromatic dicarbonyl compounds, to achieve low yellow degree index and dual refractive index, maintaining transparency and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If polyimide film is used as substrate material, then thermal stability and low CTE are improved, but yellow color and low light transmission are worsened
Solution Approach 1:
The patent uses a composite polymer structure combining polyamide and polyimide chains through copolymerization. This composite molecular structure allows the material to inherit the thermal stability of polyimide while the polyamide segments provide colorless transparency, resolving the contradiction between thermal stability and light transmission.
Solution Approach 2:
The patent changes the chemical composition parameters by controlling the molar ratio of dianhydride to dicarbonyl compound (1:1 to 4:1) and using specific aromatic diamines. This parameter optimization reduces the yellow index while maintaining thermal stability, achieving both low yellow degree and good light transmission.
2Illumination intensity
If transparent polyimide is used to reduce yellow color, then light transmission is improved, but double refraction increases
Solution Approach 1:
The patent introduces local structural diversity into the polymer chain by using a mix of fluorinated and non-fluorinated aromatic dicarbonyl compounds. This local variation in molecular structure disrupts crystallinity and reduces double refraction while maintaining overall transparency, solving the contradiction between light transmission and double refraction.
Solution Approach 2:
The patent optimizes the molar ratio of fluorinated to non-fluorinated aromatic dicarbonyl compounds to control the balance between transparency and double refraction. By adjusting this composition parameter, the patent achieves low double refraction while maintaining high light transmission.
3Stability of the object's composition
If aromatic ring density is increased to improve thermal stability, then thermal stability is improved, but yellow color worsens
Solution Approach 1:
The patent creates a composite molecular structure where polyamide segments (from aromatic diamine and dianhydride) provide thermal stability through aromatic ring density, while polyimide segments (from dicarbonyl compound) provide colorless transparency. This composite structure resolves the contradiction between thermal stability and yellow color.
Solution Approach 2:
The patent uses aromatic diamine compounds as intermediary building blocks that bridge the polyamide and polyimide structures. These diamine compounds facilitate the formation of a hybrid structure that maintains thermal stability while reducing yellow coloration through the transparent polyimide portions.
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 polyamide-imide copolymer film achieves high light transparency, low yellow index, and reduced double refraction, enhancing display quality and longevity.
Implementation Method 1
the existing transparent polyimide generally has a larger double refraction, and the larger double refraction will delay the light, thereby reducing the black and white contrast of the display
Implementation Method 2
the yellow index of the polyimide film is still relatively high, which is not enough to meet the performance required by flexible displays in the market
Data Source
AI summary
This application proposes a polyamide-imide copolymer film and a flexible display. The polyamide-imide copolymer film is obtained by copolymerizing aromatic dianhydride and aromatic dicarbonyl compound with aromatic diamine. Wherein, the aromatic dicarbonyl compounds include fluorinated aromatic dicarbonyl compound and non-fluorinated aromatic dicarbonyl compound. The polyamide-imide copolymer film can obtain a very low yellow degree index and dual refractive index, which is suitable for the substrate production of flexible display.