Polarizing Plate Adhesion via Silane Primer and pH Adjuster
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Solution Overview
Problem
Polarizing plates using polyethylene terephthalate films face issues with low adhesion force and optical inferiority due to high moisture permeability and refractive index, leading to deformation and optical defects under high temperature and humidity environments.
Innovation Solution
A polarizing plate is developed with a water-based adhesive layer containing polyvinyl alcohol-based resin, an amine-based metal compound, and a pH adjuster, along with a primer layer and a stretched polyethylene terephthalate protection film, to enhance adhesion and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyethylene terephthalate film is used as protection film to reduce manufacturing costs, then cost is reduced, but adhesion force with polyvinyl alcohol-based adhesive is low causing stripping and lifting
Solution Approach 1:
A primer layer is introduced as an intermediary between the polyethylene terephthalate film and the polyvinyl alcohol-based adhesive. The primer layer contains silane-modified polyvinyl alcohol and silane crosslinking agent, which chemically bonds to both the PET film surface and the adhesive, creating strong interfacial adhesion and preventing stripping and lifting while maintaining cost-effectiveness
2Ease of manufacture
If polyethylene terephthalate film is used as protection film, then cost is reduced, but optical inferiority occurs due to higher refractive index and retardation value causing reduced transmittance and rainbow phenomenon
Solution Approach 1:
The patent applies a primer layer with specific optical properties that compensate for the high refractive index of the PET film. The primer layer contains silane-modified polyvinyl alcohol and silane crosslinking agent, which create a gradient in refractive index and reduce optical interference, thereby minimizing the rainbow phenomenon and maintaining high transmittance while using cost-effective PET film
3Strength
If triacetyl cellulose film is used as protection film, then adhesion force is sufficient, but moisture permeability is high causing deformation under high temperature and high humidity environment
Solution Approach 1:
The patent changes the material parameters by using polyethylene terephthalate film instead of triacetyl cellulose film, which has lower moisture permeability and better dimensional stability. The primer layer with silane crosslinking further enhances the moisture resistance and adhesion, enabling the protection film to maintain performance under high temperature and high humidity conditions
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 adhesion force and water resistance, maintaining excellent optical properties and reducing the likelihood of deformation, even under high temperature and humidity conditions.
Implementation Method 1
a water-based adhesive layer, a primer layer, and a polyethylene terephthalate protection film sequentially provided on at least one surface of a polarizer, in which the water-based adhesive layer is formed by using a water-based adhesive including a polyvinyl alcohol-based resin, an amine-based metal compound, and a pH adjuster
Implementation Method 2
since the polyethylene terephthalate film has lower costs and excellent durability as compared to the other polymer films
Implementation Method 3
optical inferiority, such as a reduction in transmittance of the polarizing plate due to an increase in reflectance or the occurrence of a rainbow phenomenon due to an interference effect
Data Source
AI summary
The present invention relates to a polarizing plate including a water-based adhesive layer, a primer layer, and a polyethylene terephthalate protection film sequentially provided on at least one surface of a polarizer, in which the water-based adhesive layer is formed by using a water-based adhesive including a polyvinyl alcohol-based resin, an amine-based metal compound, and a pH adjuster, and the pH adjuster includes epoxy (meth)acrylate, alcohol, and acid, and a method for manufacturing the same.