Optical Laminate Adhesive Layer for Stable Microstructure Penetration
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Solution Overview
Problem
The penetration of adhesive layers into the concavo-convex structures of optical sheets changes over time, affecting functionality and mass producibility in optical devices, and existing methods lack efficient roll-to-roll production capabilities.
Innovation Solution
An adhesive layer with specific creep deformation rates and peel adhesive strength, composed of polymers like nitrogen-containing (meth)acrylic monomers, is used, along with a cross-linked structure and active energy ray-curable resin, to minimize penetration and maintain stability over time, enabling roll-to-roll production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer is used to attach optical sheets with concavo-convex structures, then the optical sheets can be bonded together, but the adhesive layer penetrates into the dents of the concavo-convex structure and the degree of penetration changes over time, affecting functionality
Solution Approach 1:
The patent applies parameter changes by carefully controlling the viscosity of the adhesive composition and the curing conditions to achieve an adhesive layer with specific creep deformation characteristics. The adhesive composition contains a (meth)acrylic polymer with specific molecular weight and graft polymer content, and is cured by irradiating with active energy rays such as UV light. This results in an adhesive layer that maintains penetration depth within 5-90% of convex height with minimal change over time, resolving the contradiction between adhesive strength and penetration stability.
Solution Approach 2:
The patent uses composite materials by formulating an adhesive composition containing a (meth)acrylic polymer as the base polymer, graft polymers containing cyclic ether groups, and a cationic photopolymerization initiator. This composite adhesive system provides both strong adhesion and stable penetration characteristics, as the combination of these materials creates an adhesive layer with controlled viscoelastic properties that resist excessive penetration into the concavo-convex structure.
2Ease of manufacture
If optical stacks are manufactured using conventional methods, then assembly can be achieved, but mass producibility and roll-to-roll manufacturing capability are insufficient
Solution Approach 1:
The patent replaces conventional mechanical assembly methods with a chemical bonding approach using a photopolymerization-based adhesive system. The adhesive composition contains a cationic photopolymerization initiator that cures the adhesive layer upon irradiation with active energy rays, enabling rapid bonding suitable for roll-to-roll manufacturing. This substitution of mechanical assembly with light-cured chemical bonding achieves both ease of manufacture and high productivity, as the curing process can be continuously applied in roll-to-roll production lines.
3Strength
If the adhesive layer penetrates deeply into the concavo-convex structure, then adhesion may improve, but the optical performance and functionality of the optical sheet deteriorate
Solution Approach 1:
The patent controls the penetration depth parameter by adjusting the adhesive composition's viscosity and the irradiation conditions during curing. The adhesive layer is designed to maintain penetration depth within 5-90% of the convex height of the concavo-convex structure, preventing excessive penetration that would compromise optical performance while ensuring sufficient adhesion strength through optimized material composition and curing parameters.
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 adhesive layer effectively maintains consistent penetration into concavo-convex structures, ensuring stable optical performance and facilitating mass production of optical stacks and devices.
Implementation Method 1
a creep deformation rate of 10% or less when a stress of 10000 Pa is applied at 50° C. for 1 second, and a creep deformation rate of 16% or less when a stress of 10000 Pa is applied at 50° C. for 30 minutes, in a creep test using a rotational rheometer
Implementation Method 2
an adhesive composition containing a graft polymer, which is a (meth)acrylic polymer grafted with chains containing monomers containing cyclic ether groups, and a cationic photopolymerization initiator or heat-curing catalyst
Data Source
AI summary
An adhesive layer (20a) has a creep deformation rate when a stress of 10000 Pa is applied at 50° C. for 1 second is 10% or less, and a creep deformation rate when a stress of 10000 Pa is applied at 50° C. for 30 minutes is 16% or less, in a creep test using a rotational rheometer, and has a 180° peel adhesive strength of 10 mN/20 mm or more with respect to a PMMA film.