Polyimide Hard Coating Film for Flexible Displays
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Solution Overview
Problem
Existing hard coating films for image display apparatuses face challenges in suppressing interference fringes and are difficult to apply to flexible displays due to material vulnerabilities and interference issues between substrates and coating layers.
Innovation Solution
A hard coating film with a polyimide-based substrate and a hard coating layer formed using a solvent that allows the substrate to swell, reducing refractive index differences and minimizing interference fringes, allowing the film to be applied to flexible displays with reduced reflectance oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light-transmitting substrate with an anti-reflective layer is used to reduce reflection at the image display surface, then visibility is improved, but interference fringes are generated due to refractive index differences between the substrate and coating layer
Solution Approach 1:
The patent changes the refractive index parameter of the anti-reflective coating layer by selecting specific materials (fluorocarbon resin, acrylic resin, or silane-based resin) with refractive indices carefully matched to the light-transmitting substrate. This parameter matching eliminates interference fringes while maintaining the anti-reflective function and improved visibility.
2Object-generated harmful factors
If an acrylic resin film is used as the base film in a hard coating layer to suppress interference fringes, then interference fringe generation is reduced, but the film becomes vulnerable to repeated application stress and cannot be applied to flexible image display apparatus
Solution Approach 1:
The patent changes the material parameter of the base film from vulnerable acrylic resin to polyimide, which has superior mechanical strength and flexibility. This material substitution maintains interference fringe suppression while enabling application to flexible image display apparatus that withstand repeated bending stress.
3Object-generated harmful factors
If multiple coating layers are applied to prevent interference fringes, then interference fringe generation is suppressed, but the manufacturing process becomes complex and difficult to implement
Solution Approach 1:
The patent extracts and eliminates the need for multiple complex coating layers by using a single anti-reflective coating layer with specifically matched refractive index. This simplification achieves interference fringe suppression while maintaining a straightforward, implementable manufacturing process.
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 solution effectively suppresses interference fringes and enables the application of the hard coating film to flexible image display apparatuses without compromising hardness or adhesion, achieving improved visibility and durability.
Implementation Method 1
the hard coating composition contains a solvent that allows the polyimide-based substrate to swell
Implementation Method 2
interference fringes may be generated when the refractive indices of the light-transmitting substrate and the hard coating layer are different
Data Source
AI summary
The present invention relates to a hard coating film and an image display apparatus comprising same, the hard coating film having a hard coating layer formed on at least one surface of a polyimide-based substrate, the hard coating layer comprising the cured product of a hard coating composition, wherein the hard coating composition comprises a solvent for swelling a polyimide-based resin, and the hard coating film is configured such that when the reflectivity thereof is measured in the range of 400 nm to 800 nm, the maximum amplitude difference in the oscillations of the reflectivity is controlled at 0.5% or less, and thus can prevent an interference pattern.