Poly(amide-imide) Copolymer Film for Flexible Displays
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Solution Overview
Problem
Current poly(amide-imide) copolymers face a trade-off in achieving both high mechanical and optical properties, such as high tensile modulus and low refractive index, with existing methods either improving one at the expense of the other, making them unsuitable for flexible display devices that require both toughness and excellent optical clarity.
Innovation Solution
A poly(amide-imide) copolymer is developed using a specific composition involving a diamine represented by Chemical Formula 1, a tetracarboxylic acid dianhydride, and a dicarbonyl compound, which includes an alicyclic diamine, optimizing the mole ratios to enhance both mechanical and optical properties, resulting in a film with high light transmittance, low yellowness index, and low refractive index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional poly(amide-imide) copolymers are used to improve tensile modulus, then mechanical strength increases, but optical properties such as light transmittance and refractive index deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the mole ratios of diamine (1:0.95-1.05), tetracarboxylic acid dianhydride (1:0.95-1.05), and dicarbonyl compound (0.05-0.15 mole ratio) to achieve optimal balance between mechanical strength and optical properties. This stoichiometric optimization resolves the contradiction by finding the precise compositional parameters where both tensile modulus and light transmittance are maximized simultaneously
Solution Approach 2:
The patent creates a composite poly(amide-imide) copolymer system combining multiple diamine components, tetracarboxylic acid dianhydride, and dicarbonyl compound in specific ratios. This composite approach allows the material to exhibit synergistic properties where the combination of components achieves both high mechanical strength and excellent optical properties that individual components cannot achieve alone
2Strength
If conventional poly(amide-imide) copolymers are used to improve tensile modulus, then mechanical strength increases, but yellowness index increases
Solution Approach 1:
The patent controls the yellowness index by optimizing the dicarbonyl compound content at 0.05-0.15 mole ratio and selecting specific tetracarboxylic acid dianhydride structures. This parameter optimization prevents excessive yellowing while maintaining mechanical strength, resolving the contradiction between strength improvement and color stability
3Reliability
If existing poly(amide-imide) copolymer methods are used, then either mechanical or optical properties can be improved, but not both simultaneously
Solution Approach 1:
The patent establishes specific parameter ranges (diamine 1:0.95-1.05, tetracarboxylic acid dianhydride 1:0.95-1.05, dicarbonyl compound 0.05-0.15) that simultaneously optimize both mechanical and optical properties. This structured parameter control achieves high reliability without requiring overly complex composition design, as the optimization is achieved through controlled variations in standard components
Data Source
AI summary
A poly(amide-imide) copolymer that is a reaction product of a diamine represented by Chemical Formula 1, a diamine represented by Chemical Formula 2, a dicarbonyl compound represented by Chemical Formula 3, and a tetracarboxylic acid dianhydride represented by Chemical Formula 4, a composition for preparing the poly(amide-imide copolymer, and an article including the copolymer, e.g., a film are provided:wherein, in Chemical Formulae 1 to 4, Ra, L1, L2, n1, A, R3, X, R10, R12, R13, n7 and n8 are the same as defined in the specification.