Polarizing Plate Adhesive Infiltration Control
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Solution Overview
Problem
Conventional polarizing plates using curable adhesives face issues with moisture-heat resistance due to polymerizable compound infiltration, which affects the barrier properties and curing rates of the optical film.
Innovation Solution
A polarizing plate design where polymerizable compounds are not substantially infiltrated into the optical film, using adhesives with specific SP value differences and cationic polymerizable compounds, and incorporating photoinitiators and sensitizers to control curing and adhesion, while maintaining a peelable substrate film for improved moisture-heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a curable adhesive containing polymerizable compounds is used to laminate the optical film on the polarizer, then adhesiveness is improved, but the polymerizable compounds infiltrate into the optical film causing deterioration of moisture-heat resistance
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by selecting polymerizable compounds with specific solubility parameters (SP values) that differ significantly from the optical film material. This parameter mismatch prevents infiltration while maintaining adhesion. The adhesive contains polymerizable compounds where the difference in SP value between the compound and the optical film's main component is controlled to achieve this effect.
Solution Approach 2:
The patent creates a composite adhesive system combining multiple polymerizable compounds (epoxy resin, polyol, carboxylic acid) with specific molecular structures and SP values. This composite formulation ensures strong bonding to the optical film while the specific composition prevents penetration into the film's polymer matrix, thereby maintaining moisture-heat resistance.
2Length of moving object
If the optical film thickness is reduced to achieve thinner polarizing plates, then flexibility and thinness are improved, but the barrier properties against adhesive infiltration are weakened
Solution Approach 1:
The patent addresses the thinness issue by changing the chemical parameters of the adhesive system. Even when the optical film is thin (10 μm or less), the specific SP value mismatch between the adhesive components and the optical film prevents infiltration. This allows the use of thin optical films without compromising barrier properties, as the chemical parameter control replaces the physical barrier provided by thickness.
3Ease of manufacture
If water glue-based adhesive is used for lamination, then ease of manufacture is improved, but the polarizer expansion and contraction causes curling deterioration
Solution Approach 1:
The patent replaces water-based mechanical adhesion with a chemical bonding system using polymerizable compounds. The adhesive cures through polymerization reactions (photopolymerization or condensation), creating strong chemical bonds that accommodate polarizer expansion and contraction without causing curling. This substitution of bonding mechanism eliminates the moisture-related dimensional instability issues.
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 solution provides a polarizing plate with enhanced adhesiveness and durability in high temperature and humidity environments, maintaining performance without significant infiltration of polymerizable compounds into the optical film.
Implementation Method 1
the adhesive contains at least one or more photoinitiators... irradiating the laminate with an active energy ray
Implementation Method 2
controlling the permeability of an adhesive into an optical film... the at least one or more polymerizable compounds are not substantially infiltrated into the optical film
Data Source
AI summary
A polarizing plate includes: a polarizer and an optical film, in which the optical film is laminated on at least one surface of the polarizer with an adhesive containing at least one or more polymerizable compounds, and the at least one or more polymerizable compounds are not substantially infiltrated into the optical film.