Optical Laminate Hard Coating Adhesion
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Solution Overview
Problem
Conventional plastic resin substrates for flexible and foldable display devices face challenges with insufficient hardness, scratch resistance, and flexibility, while adding fingerprint-resistant additives can compromise surface hardness and durability.
Innovation Solution
An optical laminate with a support substrate layer, a hard coating layer on both surfaces, and a fingerprint-resistant layer containing a cured product of a binder resin and an organic silane compound with specific functional groups, enhancing adhesive strength, scratch resistance, and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating layer is formed on a plastic resin substrate to improve hardness and scratch resistance, then surface hardness and scratch resistance are improved, but flexibility and curl properties deteriorate
Solution Approach 1:
The patent applies different properties to different layers: the hard coating layer provides scratch resistance and hardness, while the underlying plastic resin substrate maintains flexibility. This local differentiation allows the coating to be hard where needed (surface) while the substrate remains flexible for bending applications.
Solution Approach 2:
The patent creates a composite structure combining plastic resin substrate with hard coating layer. This composite material approach allows the final product to exhibit both the flexibility of the plastic substrate and the scratch resistance of the hard coating, resolving the contradiction between these two properties.
2Object-affected harmful factors
If additives for fingerprint resistance are added to the hard coating layer, then fingerprint resistance is improved, but surface hardness and curing density deteriorate
Solution Approach 1:
The patent separates the fingerprint resistance function from the hard coating layer by placing it in a distinct layer above the hard coating. This segmentation allows the hard coating to maintain its hardness and curing density while the separate layer provides fingerprint resistance through different mechanisms.
Solution Approach 2:
The patent introduces an intermediate layer between the hard coating layer and the outer surface. This intermediate layer serves as a mediator that provides fingerprint resistance without compromising the hardness of the underlying hard coating layer, as it sits on top rather than mixing with the hard coating material.
3Strength
If acrylate-based resin is used for hard coating to achieve high hardness, then hardness and abrasion resistance are improved, but shrinkage upon curing increases causing severe curl
Solution Approach 1:
The patent changes the material parameter by selecting a hard coating material with low shrinkage characteristics. This parameter change in material selection allows the coating to achieve high hardness without the excessive shrinkage that would cause severe curling during curing.
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 optical laminate achieves improved adhesive strength, scratch resistance, and flexibility, maintaining high hardness and fingerprint resistance, making it suitable for replacing reinforced glass cover windows in flexible or foldable display devices.
Implementation Method 1
the fingerprint-resistant layer includes a cured product of a binder resin; and an organic silane compound having at least one organic functional group selected from the group consisting of an epoxy group, a (meth)acryloxy group, a mercapto group and an amino group
Data Source
AI summary
The present disclosure provides an optical laminate which exhibits improved adhesive strength and scratch resistance together with excellent hardness and fingerprint resistance properties, by further including a fingerprint-resistant layer including an organosilane having excellent adhesion strength with the hard coating layer and an anti-fouling function on the hard coating layer including the transparent support substrate layer and the hard coating layer.