Foldable Display Protection Film Adhesion and Scratch Resistance
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Solution Overview
Problem
Conventional protective films for foldable displays often lift from the folding surface when repeatedly folded and unfolded, leading to issues with adhesion and scratch protection.
Innovation Solution
A protective film with an adhesive layer, a protective substrate, and a first hard coating layer, where the adhesive force is maintained within a specific range (10 gf/inch or more) and the substrate thickness is between 10 μm and 150 μm, ensuring secure attachment and durability without lifting or scratching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional protective films (PET or tempered glass) are applied to foldable displays, then scratch protection is provided, but the protective film lifts from the folding surface when folding and unfolding operations are repeated
Solution Approach 1:
The patent changes the adhesive parameters by formulating a specific adhesive composition containing polyurethane acrylate, polyethylene glycol diacrylate, and silane-modified polyethylene glycol as crosslinking agents. This chemical parameter change enables the adhesive to maintain stable bonding on foldable display surfaces through repeated folding operations while providing scratch protection.
Solution Approach 2:
The patent uses a composite adhesive system combining multiple polymer components (polyurethane acrylate, polyethylene glycol diacrylate, and silane-modified polyethylene glycol) to achieve both strong initial adhesion and long-term stability on foldable displays. This composite approach allows the adhesive to accommodate the mechanical stress of folding while maintaining bond integrity.
2Strength
If the protective substrate thickness is increased to improve durability and scratch resistance, then protection performance is enhanced, but the film becomes more prone to lifting during folding operations
Solution Approach 1:
The patent optimizes the protective substrate thickness parameter to a specific range of 10-150 μm. This parameter change balances the competing requirements: sufficient thickness to provide scratch resistance and durability, while thin enough to accommodate folding operations without causing adhesive failure or lifting.
3Ease of operation
If a thin protective substrate is used to facilitate folding operations, then flexibility is improved, but scratch protection and durability are reduced
Solution Approach 1:
The patent establishes a minimum thickness parameter of 10 μm for the protective substrate. This parameter setting ensures the substrate remains thin enough to allow flexible folding operations while maintaining sufficient structural integrity to provide effective scratch protection and durability.
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 film effectively prevents lifting and maintains adhesion even after repeated folding and unfolding, while providing excellent scratch resistance and durability to the foldable display device.
Implementation Method 1
the adhesive force measured at 23° C. and 50 RH % after bonding a PI substrate to the opposite surface to the surface of the adhesive layer in contact with the protective substrate is 10 gf/inch or more
Data Source
AI summary
Provided are a protective film for a foldable display and a foldable display device comprising the same.