Trigger-Activated Adhesive Film for Low-Haze Display Light Extraction
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Solution Overview
Problem
Existing adhesive films for light emitting diode displays have low light extraction efficiency due to high reflectivity and absorption at interfaces, and they also face challenges in manufacturing processability due to differences in refractive indices between layers.
Innovation Solution
An adhesive film comprising a (meth)acrylic based binder with aromatic and hydroxyl groups, inorganic particles with a high refractive index, and a trigger polymer with a melting temperature of 0°C or more, which enhances adhesive strength, optical clarity, and processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a metallic material with high index of refraction is used for touchscreen panel, then light extraction efficiency is improved, but manufacturing processability deteriorates due to difficulty in matching refractive indices with adhesive film
Solution Approach 1:
The adhesive film's refractive index is optimized to fall within 1.4-1.7, specifically matching the metallic touchscreen panel's refractive index. This parameter matching reduces interfacial reflection and improves light extraction efficiency while maintaining compatibility with standard manufacturing processes.
Solution Approach 2:
The adhesive film uses a composite formulation combining (meth)acrylic-based binder with aromatic groups, hydroxyl groups, and inorganic particles. This composite structure achieves both the required refractive index for optical performance and appropriate adhesive properties for manufacturing processability.
2Reliability
If adhesive strength is increased to ensure bonding reliability, then bonding reliability is improved, but initial adhesive strength becomes too high for proper positioning and alignment during manufacturing
Solution Approach 1:
The adhesive film is designed with low initial adhesive strength to allow easy positioning and alignment during the bonding process. After bonding is complete, heat treatment is applied to activate the trigger polymer and crosslinking reaction, which then provides high bonding reliability. This temporal separation of low initial strength and high final strength resolves the contradiction.
Solution Approach 2:
The trigger polymer undergoes a phase transition or chemical activation upon heat treatment, transforming the adhesive from a low-strength state suitable for positioning to a high-strength state for reliable bonding. This phase change enables both manufacturing ease and bonding reliability.
3Loss of energy
If inorganic particles with high index of refraction are added to increase light extraction efficiency, then light extraction efficiency is improved, but haze increases reducing optical clarity
Solution Approach 1:
Inorganic particles are strategically added to specific regions or at controlled concentrations within the adhesive film to locally enhance light extraction efficiency without causing overall haze. The particles are distributed to optimize optical performance while maintaining overall optical clarity of the film.
Solution Approach 2:
The size, shape, and concentration of inorganic particles are precisely controlled to optimize the balance between light extraction efficiency and optical clarity. By adjusting these parameters, the adhesive film achieves high light extraction without excessive haze that would compromise optical quality.
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 film significantly increases adhesive strength after heat treatment, maintains low haze for good optical characteristics, exhibits high refractive index for improved light extraction efficiency, and ensures good processability in manufacturing.
Implementation Method 1
a trigger polymer, wherein the trigger polymer has a melting temperature (Tm) of about 0° C. or more
Implementation Method 2
80% or more of light emitted from the light emitting layer is reflected or absorbed at an interface between various layer structures
Data Source
AI summary
Provided are an adhesive film, an optical member comprising same, and an optical display device comprising same, the adhesive film comprising a (meth)acryl-based binder containing an aromatic group and a hydroxyl group, inorganic particles, and a trigger polymer, wherein the trigger polymer has a melting point of about 0° C. or more, the adhesive film has a haze of about 2% or less, and an adhesive film has a ratio of adhesive strength of about 10 or more according to Equation 1.