Pressure-Sensitive Adhesive Composition for Optical Film
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Solution Overview
Problem
Pressure-sensitive adhesive compositions for optical films face challenges in maintaining optical compensation and stress relaxation under high temperature and humidity conditions, leading to light leakage and antistatic performance issues, particularly in liquid crystal display devices.
Innovation Solution
A pressure-sensitive adhesive composition comprising 60-80 parts by weight of alkyl (meth)acrylate, 1-5 parts by weight of a monomer with an alkylene oxide group, 5-20 parts by weight of a polymerizable monomer with an aromatic group, 7-12 parts by weight of hydroxyalkyl (meth)acrylate, and 0.01-0.5 parts by weight of a carboxyl group-containing polymerizable monomer, which provides excellent antistatic and optical compensation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a partially-crosslinked viscoelastic material is used to provide high temperature cohesive strength, then endurance reliability is improved, but residual stress is generated causing birefringence and light leakage
Solution Approach 1:
The patent modifies the chemical composition parameters of the pressure-sensitive adhesive by incorporating specific functional groups (carboxyl, hydroxyl, amino) and controlling the molecular weight and crosslinking density. This changes the physical properties to reduce birefringence while maintaining cohesive strength at high temperatures.
Solution Approach 2:
The patent creates a composite adhesive system combining multiple polymer components with different functions: one component provides cohesive strength through partial crosslinking, while another component with specific functional groups compensates for birefringence. This composite approach allows simultaneous achievement of reliability and optical performance.
2Adaptability or versatility
If materials with different molecular structures are used for protective film and optical film, then functional requirements are met, but dimension stability deteriorates under high temperature and humidity
Solution Approach 1:
The patent applies different functional properties to different regions of the adhesive system. The adhesive near the protective film is designed with specific crosslinking characteristics to accommodate TAC film contraction, while the bulk adhesive maintains overall dimensional stability. This localized property differentiation resolves the conflict between functional requirements and dimension stability.
3Object-affected harmful factors
If antistatic materials are added to the pressure-sensitive adhesive, then antistatic performance is improved, but contamination and temporal change in antistatic property occur
Solution Approach 1:
The patent enables the pressure-sensitive adhesive to generate and maintain antistatic properties through its own functional groups (carboxyl, hydroxyl, amino) that can interact with ambient moisture to form a conductive layer. This self-service mechanism eliminates the need for external antistatic additives, thereby avoiding contamination and temporal degradation while maintaining reliable antistatic performance.
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 achieves excellent antistatic performance with minimal temporal change, reduces light leakage, and maintains endurance reliability and workability under high temperature and humidity conditions, enhancing the performance of optical members and liquid crystal display devices.
Implementation Method 1
a polymer including 60 to 80 parts by weight of an alkyl (meth)acrylate having an alkyl group having 4 to 12 carbon atoms, 1 to 5 parts by weight of a monomer of Formula 1, 5 to 20 parts by weight of a polymerizable monomer having an aromatic group
Implementation Method 2
the pressure-sensitive adhesive layer has a residual stress under a given strain, and therefore a polymer in the crosslinked structure is oriented in a specific direction, and thus birefringence is exhibited
Implementation Method 3
dimension stability can be the problem caused by the difference in contraction or expansion behaviors of materials having unidirectional molecular arrangement at high temperature and/or high humidity
Data Source
AI summary
Provided are a pressure-sensitive adhesive composition for an optical film, which has excellent optical compensation and stress relaxation properties without changing main properties such as endurance reliability and workability under a high temperature and/or high humidity condition to minimize a light leakage phenomenon caused by stress concentration of a protective film, and an optical member and a liquid crystal display device which include a pressure-sensitive adhesive layer manufactured using the same.