Adhesive Sheet Gas Barrier Layer for Organic EL Encapsulation
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Solution Overview
Problem
Organic electroluminescent (EL) elements face degradation due to oxygen and water vapor penetration through plastic substrates, leading to reduced light emission characteristics and durability issues, with existing barrier solutions being costly or prone to cracking.
Innovation Solution
An adhesive sheet with a gas barrier layer composed of a material containing oxygen and silicon atoms, with specific atomic proportions and film density, providing excellent barrier properties, resistance to folding, and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silica vapor deposited film is used to provide barrier properties, then gas barrier properties are improved, but manufacturing cost increases due to huge equipment requirements
Solution Approach 1:
The patent changes the material composition parameters of the gas barrier layer by incorporating both inorganic particles (silica, alumina, titania, zirconia) and organic polymer components. This composite approach achieves effective gas barrier properties while using conventional coating equipment rather than expensive vapor deposition systems, thereby reducing manufacturing cost.
Solution Approach 2:
The patent employs composite materials by combining inorganic barrier particles with organic polymer matrices in the gas barrier layer. This composite structure provides both the gas blocking capability of inorganic materials and the processability of organic materials, enabling effective encapsulation without requiring costly vapor deposition equipment.
2Reliability
If a polysilazane film is formed and subjected to plasma treatment to create a gas barrier film, then gas barrier properties are improved, but cracking occurs in the gas barrier layer
Solution Approach 1:
The patent modifies the composition parameters of the gas barrier layer by incorporating flexible polymer components (polyisobutylene, polybutene) alongside inorganic particles. This compositional adjustment maintains gas barrier effectiveness while improving the layer's flexibility and resistance to cracking during device bending or thermal cycling.
Solution Approach 2:
The patent creates local quality differentiation within the gas barrier layer by distributing inorganic particles throughout an organic polymer matrix. The polymer continuous phase provides flexibility and crack resistance, while the dispersed inorganic particles provide localized gas barrier functionality, achieving both properties simultaneously.
3Strength
If a polyisobutylene based resin is used as an adhesive layer, then adhesive properties are improved, but resistance to high temperature and ultraviolet rays deteriorates
Solution Approach 1:
The patent uses composite materials in the adhesive layer by combining polyisobutylene-based resin with inorganic particles (silica, alumina, titania, or zirconia). The polymer provides adhesive functionality while the inorganic particles enhance resistance to high temperature and ultraviolet radiation, achieving both requirements simultaneously.
Solution Approach 2:
The inorganic particles act as intermediary components in the adhesive layer, mediating between the adhesive polymer and the external environment. They absorb UV radiation and resist thermal degradation, protecting the polyisobutylene resin while maintaining adhesive performance under harsh conditions.
4Adaptability or versatility
If the adhesive sheet is folded to conform to device geometry, then adaptability is improved, but gas barrier properties deteriorate due to cracking
Solution Approach 1:
The patent adjusts the compositional parameters of the gas barrier layer by incorporating flexible polymer components and optimizing inorganic particle size and distribution. This enables the layer to bend and conform to device geometries without cracking, maintaining both flexibility and gas barrier integrity.
Solution Approach 2:
The patent creates a gas barrier layer with local quality differentiation where the polymer matrix provides flexibility for bending while dispersed inorganic particles provide gas blocking. This heterogeneous structure allows the layer to adapt to device geometry while maintaining barrier functionality even when folded.
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 sheet effectively prevents gas penetration, maintains barrier properties after folding, and ensures the longevity of organic EL elements by using a polysilazane-based gas barrier layer with optimized composition and structure.
Implementation Method 1
an adhesive sheet with excellent gas barrier properties... The adhesive sheet effectively prevents gas penetration
Implementation Method 2
a method for manufacturing a gas barrier film by forming a polysilazane film on at least one surface of a film and subjecting the polysilazane film to a plasma treatment
Implementation Method 3
an adhesive sheet... comprises a base material having thereon at least a gas barrier layer and an adhesive layer
Data Source
Figure 1(A1)~1(C)
Figure 2
AI summary
The invention pertains to an adhesive sheet including a base material having thereon at least a gas barrier layer and an adhesive layer, wherein the gas barrier layer is constituted of a material containing at least an oxygen atom and a silicon atom; in a surface layer part of the gas barrier layer, an existing proportion of an oxygen atom is from 60 to 75 %, an existing proportion of a nitrogen atom is from 0 to 10 %, and an existing proportion of a silicon atom is from 25 to 35 % relative to a total existing amount of the oxygen atom, the nitrogen atom, and the silicon atom; and a film density in the surface layer part of the gas barrier layer is from 2.4 to 4.0 g/cm3, and also to an electronic device provided with the subject adhesive sheet as an electronic device member. The invention is able to provide an adhesive sheet with excellent gas barrier properties, resistance to folding and transparency and also an electronic device provided with the subject adhesive sheet as an electronic device member.