UV-Curable Epoxy Adhesive for Polarizing Plate Moisture Resistance
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Solution Overview
Problem
Existing polarizing plate adhesives face challenges such as requiring a drying process, low moisture permeability, durability issues due to moisture sensitivity, and difficulties in securing adhesive strength, especially in high humidity environments, leading to problems like surface blocking and primer-related defects.
Innovation Solution
An adhesive composition comprising a combination of epoxy-based compounds, oxetane compounds like 3,3′-oxybis(methylene)bis(3-ethyloxetane), and diacrylate-based compounds like dicyclopentadiene diacrylate, which provides excellent adhesive strength and water resistance without the need for a separate primer, stabilizing the adhesive layer under high humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aqueous adhesives are used, then ease of manufacture is improved, but durability deteriorates due to moisture sensitivity and dimensional changes
Solution Approach 1:
The patent changes the fundamental parameter of adhesive chemistry from aqueous-based to UV-curable epoxy-based system. This transformation eliminates water content that causes moisture sensitivity and dimensional changes, while maintaining ease of manufacture through UV curing process that replaces traditional drying steps.
Solution Approach 2:
The invention uses a composite adhesive system combining epoxy resin with specific additives including silane coupling agents and UV curables. This composite formulation provides both the durability of epoxy chemistry and the processability needed for manufacturing, resolving the contradiction between ease of manufacture and durability.
2Reliability
If cation-based UV adhesives are used, then durability is improved, but manufacturing precision deteriorates due to dark reaction and compression issues
Solution Approach 1:
The patent extracts and eliminates the problematic cation-based UV curing mechanism that causes dark reactions and compression issues. Instead, it employs epoxy-based chemistry with UV curables that cure cleanly without the harmful side effects, maintaining durability while improving manufacturing precision.
Solution Approach 2:
The invention replaces the problematic cation-based system with a more reliable epoxy-based system that, while potentially more expensive per unit, eliminates rework and defects that would otherwise be necessary to manage, improving overall manufacturing precision.
3Productivity
If radical-based UV adhesives are used, then productivity is improved with higher curing rate, but reliability deteriorates due to moisture vulnerability
Solution Approach 1:
The patent creates a composite adhesive system that combines epoxy resin (providing moisture resistance and durability) with UV curables (providing high curing rate). This composite formulation achieves both high productivity through rapid UV curing and high reliability through moisture-resistant epoxy chemistry.
Solution Approach 2:
The epoxy-based UV adhesive serves multiple functions simultaneously: it provides structural strength, moisture resistance, and rapid curing capability. This multi-functional adhesive resolves the contradiction between productivity and reliability by integrating benefits that were previously separated into different adhesive systems.
4Quantity of substance
If acryl adhesive is used, then cost is reduced, but manufacturing precision deteriorates due to surface blocking and primer defects
Solution Approach 1:
The patent changes the adhesive chemistry from acryl-based to epoxy-based UV curable system. This parameter change eliminates the need for primer coatings and prevents surface blocking defects, improving manufacturing precision while maintaining cost-effectiveness through a streamlined single-step UV curing process.
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 strong adhesion and maintains stability even in high humidity environments, preventing primer-related defects and ensuring durable polarizing plates with improved production yields and thermal stability.
Implementation Method 1
One of the systems that may overcome such limits of aqueous adhesives is a UV curing system that does not require a drying process since water or other solvents are not used.
Implementation Method 2
Radical adhesives have an advantage of having a relatively higher curing rate compared to cation adhesives, however, are vulnerable to moisture that hydrogen bonds formed during curing are readily weakened under a high humidity environment.
Data Source
AI summary
An adhesive composition including a first epoxy-based compound, a second epoxy-based compound, an oxetane compound, and a diacrylate-based compound is provided. A polarizing plate includes a polarizer, an adhesive layer provided on at least one surface of the polarizer and formed using the adhesive composition, and a protective film provided on at least one surface of the adhesive layer. An image display device using the polarizing plate is also provided.