Polyimide Window Cover Film with Silane Epoxy Coating for Foldable Displays
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Solution Overview
Problem
Current window cover films for flexible display devices, such as those used in foldable smartphones, lack sufficient durability and scratch resistance, particularly when subjected to repeated folding and unfolding, leading to potential cracks and reduced flexibility.
Innovation Solution
A window cover film comprising a polyimide-based base layer with a hard coating layer and an optional anti-fingerprint layer, featuring a hybrid folding resistance capacity of 30,000 or more, achieved through a specific composition and manufacturing process that includes alicyclic epoxidized silsesquioxane-based compounds, ensuring high optical clarity and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polymer plastic substrate is used as window cover material, then flexibility is improved, but hardness and scratch resistance deteriorate
Solution Approach 1:
The patent applies composite materials by combining a polyimide base layer with a hard coating layer formed from silane-modified epoxy resin. This composite structure integrates the flexibility of the polymer substrate with the hardness and scratch resistance of the coating layer, resolving the contradiction between flexibility and mechanical strength.
Solution Approach 2:
The patent changes the chemical and physical parameters of the coating layer by incorporating silane-modified epoxy resin with specific molecular weight (1,000-20,000 g/mol) and controlling the crosslinking density through silane content (5-50 wt%). These parameter adjustments optimize both the flexibility and hardness of the composite structure.
2Ease of operation
If polymer plastic substrate is used as window cover material, then flexibility is improved, but impact resistance deteriorates
Solution Approach 1:
The composite structure of polyimide base layer plus silane-modified epoxy resin coating layer provides both flexibility and impact resistance. The coating layer acts as a protective barrier that absorbs impact energy while the polyimide substrate maintains flexibility, achieving reliable impact resistance without sacrificing flexibility.
Solution Approach 2:
The hard coating layer serves as a pre-applied protective barrier that cushions against external impacts before they reach the underlying polyimide substrate. This beforehand protection enhances impact resistance while the layered structure maintains overall flexibility.
3Strength
If glass is used as window cover material, then hardness and scratch resistance are improved, but flexibility deteriorates
Solution Approach 1:
The patent replaces rigid glass with a flexible thin film structure consisting of polyimide base layer and coating layer. This flexible film structure maintains adequate hardness and scratch resistance through the coating layer while providing the essential flexibility required for foldable displays, eliminating the need for rigid glass.
Solution Approach 2:
The composite film structure combines the flexibility of polyimide with the hardness of silane-modified epoxy resin coating, creating a material that replicates the protective properties of glass while maintaining flexibility, thus replacing glass in foldable applications.
4Strength
If conventional coating is applied on plastic substrate, then scratch resistance is improved, but folding resistance deteriorates
Solution Approach 1:
The patent optimizes the molecular weight (1,000-20,000 g/mol) and crosslinking density of the silane-modified epoxy resin coating to achieve the right balance between scratch resistance and folding flexibility. The controlled silane content (5-50 wt%) ensures adequate hardness while maintaining flexibility for repeated folding.
Solution Approach 2:
The composite structure of polyimide base layer and silane-modified epoxy resin coating layer creates a synergistic effect where the coating provides scratch resistance while the layered construction allows the underlying flexible substrate to accommodate folding movements, maintaining folding resistance.
Data Source
AI summary
The present invention relates to a window cover film and a flexible display panel including the same. More particularly, the present invention relates to a window cover film including a base layer and a hard coating layer, and a flexible display panel including the same. Since the window cover film of the present invention has high surface hardness, flexibility, the excellent bending properties, the window cover film may be restored to the original form without permanent deformation and/or damage of the hard coating layer and the window cover film even though a predetermined deformation is repeated.