Radical-Curable Adhesive for Polarizing Plates
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Solution Overview
Problem
Existing radical-curable adhesives for polarizing plates face challenges in maintaining adhesive strength and heat resistance, especially in high humidity environments, due to reduced curing speed and adhesive strength when used with polyvinyl alcohol-based polarizers and protective films made of materials like acryl or cycloolefin polymers.
Innovation Solution
A radical-curable adhesive composition comprising a first compound with an ester or ether group, a second compound with a carboxyl group conjugated to a carbon-carbon unsaturated double bond, and a radical initiator, optimized in weight ratios to ensure high adhesive strength and heat resistance, even in high humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If radical-curable adhesives with acryl amide-based compounds are used to achieve high curing speed, then curing speed is improved, but adhesive strength is reduced under high humidity conditions
Solution Approach 1:
The patent modifies the chemical composition parameters of the adhesive by incorporating specific compounds (acryl amide-based compounds with hydroxyl groups, carboxyl-containing compounds, and epoxy compounds) in optimized weight ratios. This parameter change allows the adhesive to maintain high curing speed while achieving excellent adhesive strength and heat resistance even under high humidity conditions, resolving the contradiction between speed and strength
Solution Approach 2:
The patent creates a composite adhesive system by combining multiple functional components: acryl amide-based compounds (50-90 wt%) for high curing speed, carboxyl-containing compounds (5-40 wt%) for adhesive strength, and epoxy compounds (1-10 wt%) for heat resistance. This composite approach synergistically resolves the contradiction between curing speed and adhesive strength under high humidity
2Strength
If additional processes such as hot-air drying or plasma treatment are applied to the polarizer before applying adhesive, then adhesive strength is improved, but manufacturing complexity and production time increase
Solution Approach 1:
The adhesive composition is designed to inherently provide excellent adhesion to the polarizer surface without requiring external pre-treatment processes. The chemical composition (acryl amide-based compounds with hydroxyl groups, carboxyl-containing compounds, and epoxy compounds) enables the adhesive to self-bond effectively to the polarizer, eliminating the need for hot-air drying or plasma treatment and thereby reducing manufacturing complexity
Solution Approach 2:
The adhesive formulation is pre-engineered with compounds that provide immediate bonding capability upon application. The acryl amide-based compounds with hydroxyl groups and carboxyl-containing compounds are specifically selected to create strong initial adhesion to the polarizer surface, allowing the adhesive to perform its bonding function without requiring preliminary surface treatment steps
3Ease of operation
If aqueous adhesives are used to achieve ease of application, then ease of operation is improved, but adhesive strength is weak when acryl-based films or COP films are used as protective films
Solution Approach 1:
The patent changes the fundamental parameter of the adhesive from aqueous-based to non-aqueous radical-curable composition. This parameter change enables the adhesive to achieve strong bonding with acryl-based films and COP films while maintaining ease of application through simple coating and UV curing processes, resolving the contradiction between ease of operation and adhesive strength
4Strength
If a drying process is applied to aqueous adhesive to achieve adhesion, then adhesive strength is improved, but defects increase due to moisture permeability differences and heat expansion
Solution Approach 1:
The patent replaces the mechanical drying process (heat evaporation of water) with a photochemical curing mechanism. The radical-curable adhesive composition cures through UV light irradiation, eliminating the need for thermal drying and thereby avoiding defects caused by moisture permeability differences and heat expansion in the protective films, while still achieving excellent adhesive strength
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 composition achieves excellent adhesive strength and high heat resistance, enabling its use in polarizing plates without additional treatments, while maintaining productivity and stability in high humidity environments.
Implementation Method 1
radical-curable adhesive composition including a first compound represented by the following [Chemical Formula I]; a radical-curable second compound including at least one carboxyl group conjugated with a carbon-carbon unsaturated double bond present in the side chain in the molecule; and a radical initiator
Data Source
AI summary
The present invention relates to a radical-curable adhesive composition including a first compound represented by [Chemical Formula I]; a radical-curable second compound including at least one carboxyl group conjugated with a carbon-carbon unsaturated double bond present in the side chain in the molecule; and a radical initiator, and a polarizing plate including the radical-curable adhesive composition.