High Refractive Index Acrylic Adhesive for Display Luminance

Solution Overview

Problem

Existing adhesives for image display devices, such as LCD and OLED devices, face challenges in maintaining transparency and adhesiveness while addressing refractive index differences between encapsulation layers and polarizing plates, often requiring additional high refractive index layers that increase device thickness and complexity.

Innovation Solution

An adhesive composition incorporating an acrylic copolymer and a compound with a sulfide group, providing a refractive index of 1.57 or more, which reduces the need for a separate high refractive index layer by maintaining or increasing refractive properties while lowering elastic modulus and glass transition temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a separate high refractive index layer is coated between the encapsulation layer and the adhesive for a polarizing plate, then the refractive index difference is reduced and luminance is improved, but the thickness of the image display device is increased and the process becomes more complicated

Engineering Contradiction:

ImproveluminanceVSAvoidprocess complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent combines the adhesive function and the high refractive index function into a single adhesive layer. The adhesive composition includes a polymer matrix with refractive index of 1.50-1.56 and a sulfide group-containing compound (refractive index 1.57 or more) at 1-50 wt%, creating a multi-functional material that eliminates the need for a separate high refractive index layer while maintaining luminance improvement

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The adhesive layer is designed to perform multiple functions simultaneously: providing adhesion between the encapsulation layer and polarizing plate, maintaining transparency, and reducing reflection through high refractive index properties. This multi-functional design eliminates the need for additional dedicated layers

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Illumination intensity

If a separate high refractive index layer is coated between the encapsulation layer and the adhesive for a polarizing plate, then the refractive index difference is reduced and luminance is improved, but the thickness of the image display device is increased

Engineering Contradiction:

ImproveluminanceVSAvoiddevice thickness

Core Design Contradiction:

Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent combines the adhesive function and the high refractive index function into a single adhesive layer. The adhesive composition includes a polymer matrix with refractive index of 1.50-1.56 and a sulfide group-containing compound (refractive index 1.57 or more) at 1-50 wt%, creating a multi-functional material that eliminates the need for a separate high refractive index layer while maintaining luminance improvement

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The adhesive layer is designed to perform multiple functions simultaneously: providing adhesion between the encapsulation layer and polarizing plate, maintaining transparency, and reducing reflection through high refractive index properties. This multi-functional design eliminates the need for additional dedicated layers

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Illumination intensity

If the refractive index of the adhesive is increased to match the encapsulation layer, then reflection at the interface is reduced and luminance is improved, but the adhesive may lose its adhesive properties

Engineering Contradiction:

ImproveluminanceVSAvoidadhesive properties

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent creates a composite adhesive material consisting of a polymer matrix (providing adhesive properties) and sulfide group-containing compounds (providing high refractive index). This composite structure allows the adhesive layer to simultaneously achieve refractive index of 1.57 or more and maintain excellent adhesive properties including adhesion to both the encapsulation layer and polarizing plate

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the refractive index parameter of the adhesive material by incorporating sulfide group-containing compounds with high refractive index (1.57 or more) into the polymer matrix, changing the optical properties while maintaining the mechanical and adhesive properties through proper composition design

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11976223B2Adhesive composition, adhesive sheet and image display device prepared from the same

Publication Date: 2024.05.07 DONGWOO FINE CHEM CO LTD

AI summary

An adhesive composition according to an embodiment includes an acrylic copolymer, and a compound containing a sulfide group and having a refractive index of 1.57 or more. The adhesive sheet prepared from the adhesive composition may have a low glass transition temperature and high refractive index, such that an image display device may not include a separate high refractive index pattern layer.