Polyimide Optical Multilayer Structure for Reduced Curling
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Solution Overview
Problem
Conventional polyimide films used in display devices face issues with curling due to thermal expansion coefficient differences, leading to decreased surface hardness and adhesiveness, and lack of shattering resistance.
Innovation Solution
An optical multilayer structure is developed with an adhesion promoting layer and a shatterproof layer formed by polyimide resin compositions, connected via imide bonds, to minimize curling and enhance durability and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a polyimide film is used as a substrate or cover window material, then it can replace tempered glass, but it exhibits curling due to thermal expansion coefficient differences
Solution Approach 1:
The patent divides the polyimide film into multiple layers with different thicknesses (first polyimide layer, second polyimide layer, third polyimide layer) to independently control and compensate for thermal expansion effects in each layer, thereby reducing overall curling while maintaining the film's versatility as a replacement for tempered glass
Solution Approach 2:
The patent changes the thickness parameter of different polyimide layers to achieve optimal balance between flexibility and curling resistance. By varying the thickness of each layer, the thermal expansion behavior is modified to minimize curling while preserving the ability to replace tempered glass in display devices
2Stability of the object's composition
If the polyimide film structure is modified to reduce curling, then thermal expansion stability improves, but surface hardness decreases
Solution Approach 1:
The patent creates a composite structure by combining multiple polyimide layers with different thicknesses and properties. This composite approach allows the film to achieve thermal expansion stability through the layered configuration while maintaining surface hardness through the specific composition and curing characteristics of the polyimide resin system
3Adaptability or versatility
If the polyimide film is made more flexible for foldable displays, then adaptability improves, but shattering resistance decreases
Solution Approach 1:
The patent segments the film into multiple layers that can independently deform during folding while collectively providing shattering resistance. The layered structure allows flexibility for foldable display applications while the combined thickness and composition provide sufficient strength to resist shattering during use
Solution Approach 2:
The patent optimizes the thickness parameter of each polyimide layer to achieve the right balance between flexibility and shattering resistance. By carefully controlling the thickness of each layer, the film becomes sufficiently flexible for foldable displays while maintaining enough overall strength to prevent shattering
4Ease of manufacture
If conventional polyimide composition is used, then manufacturing simplicity is maintained, but adhesiveness and durability are insufficient
Solution Approach 1:
The patent uses a composite polyimide resin composition that combines multiple components to enhance adhesiveness and durability while maintaining manufacturing simplicity. The resin composition includes specific polymers and additives that promote strong bonding and long-term durability without complicating the standard coating and curing 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 structure improves durability and shattering resistance while maintaining flexibility, with enhanced adhesiveness and reduced substrate bending.
Implementation Method 1
applying a polyimide precursor composition on any one or both surfaces of a substrate and drying the composition to form an adhesion promoting layer
Implementation Method 2
applying a polyimide precursor composition comprising a structural unit represented by Chemical Formula 1 and curing the composition to form a shatterproof layer
Implementation Method 3
the adhesion promoting layer and the shatterproof layer provide an optical multilayer structure connected by an imide bond
Data Source
AI summary
Provided is an optical multilayer structure including a shatterproof layer including a polyimide resin including a siloxane structure and an adhesion promoting layer. Since the adhesion promoting layer and the shatterproof layer of the optical multilayer structure according to one implementation are connected by a chemical bond (imide bond), interlayer adhesiveness is high and durability is excellent. In addition, the optical multilayer structure according to one implementation has excellent heat resistance, so that curling is reduced to minimize substrate bending, has high surface hardness, so that mechanical properties are excellent, and has a low haze and is transparent, so that optical properties are excellent.