Polyimide Copolymer Transparency via Local Quality Modification
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Solution Overview
Problem
Aromatic polyimide resins face limitations in achieving transparency due to charge transfer complexes, and polyamideimide copolymers with improved mechanical properties struggle with adhesiveness, insulation, and pattern properties for optical devices.
Innovation Solution
A polyimide copolymer with specific repeat units derived from aromatic diamine and epoxy compounds, allowing for low-temperature curing, enhanced adhesion, and improved mechanical properties, along with a method for preparing this copolymer and its application in photosensitive resin compositions and films for optical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic polyimide resins are used to achieve heat resistance and chemical resistance, then excellent thermal and chemical properties are obtained, but the resins appear dark brown due to charge transfer complexes and transparency cannot be secured
Solution Approach 1:
The patent applies local quality by selectively modifying specific positions in the polyimide molecular structure. Electron-withdrawing groups (trifluoromethyl, cyano, nitro) are introduced at specific locations on the aromatic rings to restrict π electron movement locally, preventing charge transfer complex formation while maintaining the overall rigid chain structure for heat resistance. This localized modification allows transparency improvement without sacrificing thermal stability.
Solution Approach 2:
The patent employs composite material strategy by creating polyimide copolymers that combine different structural units. The copolymer contains both the heat-resistant polyimide backbone and functional groups that prevent CTC formation. This composite approach integrates the advantages of both heat resistance and transparency into a single material system, achieving dual performance characteristics.
2Ease of manufacture
If sulfone or ether groups are introduced to reduce charge transfer complex formation and improve transparency, then colorless transparent polyimide can be obtained, but the resins exhibit poor mechanical properties due to curved structures
Solution Approach 1:
Instead of introducing curved sulfone or ether groups throughout the polymer chain, the patent applies local quality by placing electron-withdrawing groups at specific positions on the aromatic rings. This localized approach restricts π electron movement without creating macroscopic curve structures, thereby maintaining the linear rigid chain configuration necessary for excellent mechanical properties while still preventing charge transfer complex formation.
Solution Approach 2:
The patent changes the electronic parameters of the polyimide molecule by introducing electron-withdrawing groups with specific electronic characteristics (high electronegativity). This parameter change affects the electron distribution and energy levels, preventing CTC formation and improving transparency. Simultaneously, the rigid aromatic structure with these substituents maintains or even enhances mechanical strength through improved intermolecular interactions.
3Strength
If polyamideimide copolymer is used to improve mechanical properties through crystallinity, then scratch resistance is enhanced, but adhesiveness and pattern properties are insufficient for optical devices
Solution Approach 1:
The patent applies local quality by introducing electron-withdrawing groups at specific positions in the polyimide copolymer structure. This localized modification prevents charge transfer complex formation and improves transparency and pattern properties, while the overall copolymer structure maintains the crystallinity and scratch resistance characteristics of polyamideimide materials.
Solution Approach 2:
The patent uses composite material strategy by creating a polyimide copolymer that combines the mechanical properties of polyamideimide with the optical properties of modified polyimide. The copolymer structure integrates rigid crystalline regions for scratch resistance with electron-withdrawing groups for transparency and improved adhesion, achieving a balance of multiple properties required for optical device applications.
4Reliability
If conventional polyimide resin is used to achieve insulation properties, then electrical insulation is obtained, but curing temperature is high and processing is difficult
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide by introducing electron-withdrawing groups and creating a copolymer structure. This structural modification alters the curing characteristics, enabling low-temperature curing while maintaining the electrical insulation properties of polyimide. The copolymer structure provides sufficient reactivity for low-temperature processing without compromising the final insulation performance.
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 polyimide copolymer achieves excellent adhesive strength, mechanical properties, and insulation while facilitating pattern formation, making it suitable for various optical devices with improved durability and reliability.
Implementation Method 1
capable of curing at low temperature
Implementation Method 2
photosensitive resin composition, photosensitive resin film
Data Source
AI summary
The present invention provides a polyimide copolymer containing repeating units having a specific structure derived from monomers synthesized from an epoxy compound, a method for preparing the polyimide copolymer, a photosensitive resin composition, a photosensitive resin film and an optical device including the same.