Acrylic Adhesive Composition for Polarizing-Plate Reworkability
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Solution Overview
Problem
Existing adhesive compositions for polarizing plates face challenges in maintaining a balance between adhesion force, reworkability, and durability, especially under high-temperature and high-humidity conditions, leading to issues such as separation, bubble formation, and reduced processability.
Innovation Solution
An acrylic adhesive composition incorporating a (meth)acrylic copolymer, an isocyanate-based multi-functional curing agent, and two types of curing retarders with different deblocking temperatures, along with a silane coupling agent, to control curing and enhance adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an excessive amount of curing agent is used to increase the degree of curing, then durability is improved, but adhesion force is reduced causing separation of polarizing plate
Solution Approach 1:
The patent introduces a curing retarder as an intermediary substance that mediates between the curing agent and the adhesive system. The curing retarder controls the release of the curing agent, allowing gradual curing progression that maintains both adhesion force and durability without the extremes of excessive curing or insufficient curing
Solution Approach 2:
The curing retarder performs preliminary action by delaying the curing process until appropriate conditions are met. This preliminary delay allows the adhesive to achieve sufficient adhesion strength before curing progresses, preventing separation while still enabling complete curing for durability
2Strength
If the content of curing agent is reduced to increase adhesion force, then adhesion force is improved, but due to low degree of crosslinking, cohesive force decreases under high-temperature/high-humidity conditions resulting in bubble formation
Solution Approach 1:
The curing retarder acts as a mediator that enables the system to achieve low adhesion force initially (for reworkability) while ensuring sufficient crosslinking later (for durability). It controls the timing of curing agent release to match the needs of different process stages
Solution Approach 2:
The patent creates a dynamic curing process where the curing agent's activity is modulated over time. The curing retarder enables the system to transition from a dynamic state (low crosslinking, high adhesion) to a stable state (high crosslinking, high durability) under appropriate conditions
3Strength
If acid-based copolymer is applied to increase adhesion force, then adhesion force is improved, but reworkability reduces so that processability is reduced
Solution Approach 1:
The patent creates a dynamic adhesion system where the adhesive properties can be adjusted over time. The controlled curing process allows the adhesive to maintain softness and reworkability during the assembly process, then progressively develop full adhesion strength after curing, enabling both easy operation and strong bonding
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 composition provides excellent adhesion force and durability under varying environmental conditions, preventing gelation and maintaining performance even at high temperatures, while allowing for reworkability without compromising cohesive strength.
Implementation Method 1
an isocyanate-based multi-functional curing agent
Implementation Method 2
a silane coupling agent
Data Source
AI summary
The present invention relates to an acrylic adhesive composition, and a polarizing plate and a display device manufactured using the same, wherein the acrylic adhesive composition includes an acrylic copolymer formed by polymerizing a monomer mixture including a (meth)acrylic monomer and a (meth)acrylic monomer containing a hydroxy group, an isocyanate-based multi-functional curing agent, a curing retarder including a first curing retarder having a deblocking temperature of 110° C. or lower and a second curing retarder having a deblocking temperature of 130° C. or higher, and a silane coupling agent.