Multilayer Sheet for Flexible Displays
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Solution Overview
Problem
Existing surface protection sheets for displays, particularly flexible and foldable displays, face challenges in maintaining adhesion and durability over a wide temperature range, resisting external impacts, and preventing interlayer separation during repeated bending or rolling.
Innovation Solution
A multilayer sheet comprising an elastic layer with a storage modulus of 10 MPa to 3,000 MPa and an adhesive layer with a storage modulus of 1 MPa to 50 MPa, where the adhesive layer has an adhesive force of 2 N/inch or more after curing, ensuring reliable adhesion and resistance to external impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a surface protection sheet is applied to flexible and foldable displays, then scratch resistance is improved, but interlayer separation occurs during repeated bending or rolling
Solution Approach 1:
The protection sheet is divided into multiple layers: a hard coating layer for scratch resistance, an elastic layer for flexibility and adhesion, and an adhesive layer for bonding. This segmentation allows each layer to perform its specific function without compromising the others during bending operations
Solution Approach 2:
The invention uses composite material structure combining a hard coating material (for scratch resistance), an elastic polymer material (for flexibility and adhesion maintenance), and an adhesive material (for strong bonding). This composite structure resolves the contradiction by integrating materials with complementary properties that work together during repeated bending
2Strength
If the protection sheet is made more rigid to resist external impacts, then impact resistance is improved, but adhesion deteriorates over wide temperature range
Solution Approach 1:
Different layers of the protection sheet have different mechanical properties optimized for their specific functions: the hard coating layer provides impact resistance at the surface, while the elastic layer provides temperature-stable adhesion at the bonding interface. This local differentiation of material properties resolves the contradiction between impact resistance and adhesion stability
3Ease of operation
If the protection sheet is made thinner to maintain flexibility, then flexibility is improved, but durability against repeated folding deteriorates
Solution Approach 1:
The composite structure combines a thin hard coating layer (for scratch protection) with an elastic layer of optimized thickness (for flexibility and durability). The elastic layer's specific thickness range (5-50 μm) provides sufficient mechanical strength for repeated folding while maintaining overall flexibility of the protection sheet
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 multilayer sheet effectively inhibits peeling from the attachment target even with repeated bending or rolling over a wide temperature range, prevents interlayer separation, and provides resistance to external impacts, ensuring reliable protection for flexible and foldable displays.
Implementation Method 1
an adhesive layer disposed on a surface of the elastic layer, wherein a storage modulus of the multilayer sheet measured at 20° C. is 10 MPa to 2,000 MPa
Implementation Method 2
an elastic layer and an adhesive layer disposed on a surface of the elastic layer
Implementation Method 3
a storage modulus of the multilayer sheet measured at 20° C. is 10 MPa to 2,000 MPa
Data Source
AI summary
The multilayer sheet of the present disclosure includes an elastic layer and an adhesive layer disposed on a surface of the elastic layer, wherein a storage modulus of the multilayer sheet measured at 20° C. is 10 MPa to 2,000 MPa.