Composite Film Lamination for Foldable Display Durability
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Solution Overview
Problem
Flexible display devices, particularly foldable displays, face durability issues due to the vulnerability of transparent polyimide (TPI) cover windows to repeated impacts and deformations, necessitating improved bonding materials and methods.
Innovation Solution
A method involving the lamination of a polyether block amide copolymer sheet with a carrier film, using a polyimide-based resin, to create a composite film that maintains adhesion through dynamic bending tests, without delamination, by ensuring rapid contact and controlled bonding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent polyimide (TPI) is used as the cover window material, then transparency and flexibility are achieved, but durability and resistance to repeated impacts deteriorate
Solution Approach 1:
The patent uses a composite film structure consisting of a polyether block amide copolymer layer and a polyimide-based carrier film layer. This composite structure combines the flexibility and transparency of the copolymer with the durability and impact resistance of the polyimide carrier, resolving the contradiction between transparency and durability.
2Strength
If the sheet is laminated with the carrier film immediately after extrusion, then adhesion strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies the carrier film to the extruded sheet immediately after extrusion, within 30 seconds, while the sheet is still warm and pliable. This preliminary action ensures strong adhesion without requiring additional bonding agents or complex processing steps later.
Solution Approach 2:
The patent controls the temperature and timing parameters of the lamination process, specifically requiring contact within 30 seconds of extrusion and maintaining temperatures between 100°C to 200°C, to achieve optimal adhesion while simplifying the manufacturing process.
3Reliability
If the composite film is tested under extreme bending conditions, then durability is verified, but test complexity and time requirements increase
Solution Approach 1:
The patent establishes clear acceptance criteria for durability testing, including passing 200,000 bending cycles without delamination and maintaining adhesion strength of at least 50% of the initial value. These feedback-based criteria enable standardized testing that verifies durability without excessive complexity.
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 composite film exhibits excellent durability with no delamination after 200,000 cycles of bending tests at various temperatures, maintaining structural integrity and reducing haze, suitable for foldable displays.
Implementation Method 1
The laminating operation brings the sheet into contact with the carrier film within 30 seconds of the start of the extrusion... The composite film may maintain adhesion not to occur the delamination after 200,000 cycles of dynamic bending tests
Data Source
AI summary
Embodiments provide: a method for manufacturing a composite film, the method comprising a laminating operation of extruding a raw material including a polyether block amide copolymer into a sheet form and coming the sheet into contact with a carrier film to obtain a laminate, and a winding operation of winding the laminate, to thereby complete the manufacture of a composite film comprising the laminate, wherein the laminating operation comprises coming the sheet into contact with the carrier film within 30 seconds from the start of the extrusion; and a composition film which is not separated even after 200,000 cycles of dynamic bending tests at a temperature of −40° C. with a curvature radius of 1.5 mm and a bending speed of 1 second per 1 time in accordance with IEC 62715-6-1 standard.