Hardcoat Film Elastic Modulus Thickness Criteria
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Solution Overview
Problem
Existing hardcoat films for image display devices fail to simultaneously achieve sufficient hardness and resistance to repeated folding, particularly when folded with the substrate facing inward, leading to cracking issues.
Innovation Solution
A hardcoat film with a substrate and a hardcoat layer that satisfies specific elastic modulus and thickness criteria, incorporating a cured product of a composition containing polyorganosilsesquioxane with hydrogen-bonding groups and a crosslinkable (meth)acrylamide group, and optionally an anti-scratch layer, to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hardcoat layer is provided on a substrate to increase hardness, then scratch resistance is improved, but the film cracks when folded with the substrate facing inward
Solution Approach 1:
The patent changes the chemical composition parameters of the hardcoat layer by incorporating polyorganosilsesquioxane with specific functional groups (hydrogen-bonding groups and crosslinkable groups). This compositional parameter change enables the hardcoat layer to achieve both high hardness and flexibility, resolving the contradiction between scratch resistance and fold resistance.
Solution Approach 2:
The patent creates a composite material system by combining polyorganosilsesquioxane with hydrogen-bonding groups (such as carboxyl, hydroxyl, or amine groups) and crosslinkable groups (such as epoxy or vinyl groups). This composite structure provides both the hardness needed for scratch resistance and the flexibility required to prevent cracking during folding.
2Strength
If the hardcoat layer is made thicker to improve hardness, then scratch resistance increases, but flexibility and resistance to folding decreases
Solution Approach 1:
The patent changes the material parameters by using polyorganosilsesquioxane with specific functional groups that enable strong intermolecular hydrogen bonding and crosslinking. This parameter change allows the hardcoat layer to maintain high hardness while achieving the flexibility needed for repeated folding, effectively decoupling the thickness-hardness-f Flexibility relationship.
Solution Approach 2:
The patent implements local quality by creating a hardcoat layer with specific local chemical structures - hydrogen-bonding groups for strength and flexibility, and crosslinkable groups for network formation. These localized functional groups distribute stress differently throughout the material, enabling both hardness and flexibility without requiring specific thickness.
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 exhibits improved hardness and resistance to repeated folding without cracking, maintaining pencil hardness and scratch resistance, while the anti-scratch layer further enhances durability.
Implementation Method 1
the polyorganosilsesquioxane has a constitutional unit (S1) that has a group containing a hydrogen atom capable of forming a hydrogen bond
Implementation Method 2
the constitutional unit (S2) that is different from the constitutional unit (S1) and has a crosslinkable group... the crosslinkable group that the constitutional unit (S2) has is a (meth)acrylamide group
Data Source
AI summary
A hardcoat film includes: a substrate; and a hardcoat layer, in which the hardcoat film satisfies the following Formulas (i) and (ii), (i) E′(0.4)HC×dHC≥8,000 MPa·μm, (ii) E′(4)HC×dHC≤4,000 MPa·μm, E′(0.4)HC is an elastic modulus of the hardcoat layer obtained in a case where an elongation rate is 0.4%, E′(4)HC is an elastic modulus of the hardcoat layer obtained in a case where an elongation rate is 4%, and dHC is a film thickness of the hardcoat layer.