Polarizing Plate Adhesion via Urethane Resin Cross-Linking
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Solution Overview
Problem
The adherence between polarizers and protective films in liquid crystal display devices is insufficient, particularly under high-temperature and high-humidity conditions, which affects the durability and performance of the devices.
Innovation Solution
A polarizing plate is developed with an adhesive layer containing a urethane resin with a carboxyl group and a cross-linking agent, along with an easy-adhesion layer formed using a polyvinyl alcohol resin and corona discharge treatment on the protective film, enhancing the adhesion between the polarizer and the protective film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an easy-adhesion layer is provided and corona discharge treatment is applied to enhance adhesion, then adhesion property is improved, but adherence remains insufficient under high-temperature and high-humidity conditions
Solution Approach 1:
The patent uses a composite adhesive layer containing both a polyvinyl alcohol resin and a urethane resin with carboxyl groups. This composite material combines the easy-adhesion properties of polyvinyl alcohol with the heat and moisture resistance of cross-linked urethane, resolving the contradiction between initial adhesion and durability under harsh conditions.
Solution Approach 2:
The patent modifies the chemical parameters of the adhesive layer by introducing cross-linking agents that react with the carboxyl groups of the urethane resin. This cross-linking creates a three-dimensional network structure that significantly improves resistance to thermal and moisture degradation while maintaining adhesion properties.
2Ease of operation
If a polyvinyl alcohol resin is used for the adhesive layer, then ease of adhesion is improved, but resistance to heat and moisture is insufficient
Solution Approach 1:
The patent combines polyvinyl alcohol resin (providing ease of adhesion) with urethane resin containing carboxyl groups (providing heat and moisture resistance). The synergistic effect of this composite material allows the adhesive layer to simultaneously achieve easy adhesion and high reliability under harsh environmental conditions.
Solution Approach 2:
The patent changes the chemical structure of the adhesive layer by incorporating cross-linking agents that form cross-linked networks with the urethane resin. This structural modification enhances the thermal and moisture resistance of the adhesive layer while preserving its adhesion characteristics.
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 significantly improves the adherence between the polarizer and the protective film, ensuring excellent performance under high-temperature and high-humidity conditions, with the polarizing plate demonstrating enhanced durability and resistance to moisture and heat.
Implementation Method 1
an easy-adhesion layer formed of an easy-adhesive composition containing a urethane resin having a carboxyl group and a cross-linking agent
Implementation Method 2
the protective film is subjected to corona discharge treatment or plasma treatment on a side on which the polarizer is placed
Data Source
AI summary
The present invention provides a polarizing plate excellent in adherence (particularly, under high-temperature and high-humidity conditions) between a polarizer and a protective film. The polarizing plate of the present invention includes: a polarizer; an adhesive layer; an easy-adhesion layer formed of an easy-adhesive composition containing a urethane resin having a carboxyl group and a cross-linking agent; and a protective film containing a (meth)acrylic resin.