Polyimide Films with Fluorene and Alicyclic Structures
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Solution Overview
Problem
Conventional polyimides with alicyclic monomers or fluorene structures either lack solubility in organic solvents, transparency, or optical isotropy, failing to meet the demands for heat resistance, transparency, and solubility simultaneously.
Innovation Solution
A polyimide and polyamic acid are developed using a monomer with an alicyclic tetracarboxylic dianhydride and a fluorene skeleton, providing structures that offer heat resistance, transparency, and solubility in organic solvents, along with optical isotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polyimide with an alicyclic monomer structure is used to improve transparency and heat resistance, then transparency and heat resistance are improved, but solubility in organic solvents deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide by introducing specific alicyclic tetracarboxylic dianhydride structures (such as 1,2,4,5-cyclohexanetetracarboxylic dianhydride) and controlling the diamine components. This structural parameter change enables the polyimide to maintain high transparency and heat resistance while achieving solubility in organic solvents like NMP and DMAc, thus resolving the contradiction between transparency and solubility.
2Ease of manufacture
If a polyimide with a fluorene structure is used to improve solubility and optical properties, then solubility and optical isotropy are improved, but heat resistance deteriorates
Solution Approach 1:
The patent creates a composite polyimide structure by combining alicyclic tetracarboxylic dianhydride units with specific diamine units (such as 4,4'-diaminodiphenyl ether and 2,2-bis(4-aminophenyl)propane). This composite structure integrates the beneficial properties of both alicyclic structures (heat resistance, transparency) and fluorene-like structures (solubility, optical isotropy), achieving a balance among solubility, heat resistance, and optical properties.
3Temperature
If conventional polyimide materials are used to achieve heat resistance, then heat resistance is improved, but optical isotropy and transparency deteriorate
Solution Approach 1:
The patent applies local quality control by specifically designing the polyimide structure with alicyclic tetracarboxylic dianhydride units at key positions in the polymer chain. This localized structural arrangement ensures that the polyimide exhibits high heat resistance (glass transition temperature of 250°C or higher) while maintaining excellent transparency (light transmittance of 70% or more at 400 nm) and optical isotropy (phase difference of 0.05 μm or less), thus resolving the contradiction between heat resistance and optical properties.
Data Source
AI summary
Objects of the present invention are: to obtain a polyimide that is excellent in heat resistance, transparency, and optical isotropy and is soluble in an organic solvent; to provide, by using either a polyimide or a polyamic acid which is a precursor or the polyimide, a product or a member that is highly required to have heat resistance and transparency; and particularly to provide a product and a member both of which are obtained by applying a polyamic acid solution and a polyimide solution of the present invention to the surface of an inorganic substance such as glass, metal, metal oxide, or a single crystal silicon. These objects can be attained by a polyimide acid and a polyimide which are each prepared from an alicyclic tetracarboxylic dianhydride and a monomer having a fluorene structure.