Thin Polarizer Manufacturing via Single Stretching of Crosslinked PVA Film
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Solution Overview
Problem
Current methods for manufacturing thin polarizers using polyvinyl alcohol-based films face challenges in achieving thin thickness while maintaining excellent optical characteristics and productivity, as they often result in film breakage and damage during the stretching process, and require complex separation processes that can degrade optical properties.
Innovation Solution
A method involving a single stretching step of an unstretched polyvinyl alcohol-based film with a thickness of 20 μm or less, applying a strength of 4 N or more to achieve a thickness of 10 μm or less, without the need for a base film, using a wet or dry stretching process in an aqueous boric acid solution, and optimizing the film's elastic modulus and dyeing process to enhance stretchability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a polyvinyl alcohol-based film with thickness of 60 μm or less is used before stretching, then the thickness of the polarizer can be reduced, but the breaking strength deteriorates and film breakage occurs during stretching
Solution Approach 1:
The patent changes the physical-chemical parameters of the polyvinyl alcohol film by controlling the polymerization degree (1,500 to 3,500) and incorporating crosslinking agents (boric acid, zinc sulfate, or aluminum sulfate at 0.1-5.0 wt%). These parameter changes enhance the film's mechanical strength and elasticity, allowing thin films (20 μm or less) to withstand the stretching process without breakage while achieving the desired thin polarizer thickness of 10 μm or less.
2Volume of moving object
If a laminate structure with base material layer and hydrophilic polymer layer is used, then thin polarizers can be manufactured, but the separation process damages the polyvinyl alcohol layer and deteriorates optical properties
Solution Approach 1:
The patent extracts and eliminates the base material layer from the laminate structure, using only the polyvinyl alcohol film itself. By removing the need for a separate base material layer and subsequent separation process, the invention prevents damage to the polyvinyl alcohol layer and preserves optical properties while still achieving thin polarizer thickness through the enhanced mechanical properties of the crosslinked PVAl film.
3Volume of moving object
If coating or co-extrusion method is used to manufacture thin polarizers, then thin thickness can be achieved, but the manufacturing process becomes complex and productivity decreases
Solution Approach 1:
The patent applies preliminary action by pre-treating the polyvinyl alcohol film with crosslinking agents (boric acid, zinc sulfate, or aluminum sulfate) and controlling polymerization degree before stretching. This preliminary crosslinking and parameter optimization enhances the film's stretchability and mechanical strength, allowing direct stretching of thin films without requiring complex coating or co-extrusion equipment, thereby simplifying the manufacturing process and improving productivity.
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
This approach allows for the production of thin polarizers with excellent optical properties, including a single transmittance of 40% to 45% and a polarization degree of 99% or more, while simplifying the manufacturing process and preventing film damage, thereby improving productivity and stability.
Implementation Method 1
stretching the polyvinyl alcohol-based film in a predetermined direction
Implementation Method 2
the swelling degree of the polyvinyl alcohol-based film is increased
Implementation Method 3
dyeing a polyvinyl alcohol-based film with iodine or a dichroic dye
Implementation Method 4
performing a cross-linking process
Data Source
AI summary
The present invention relates to a method for manufacturing a thin polarizer, the method including: a step of preparing an unstretched polyvinyl alcohol-based film having a thickness of 20 μm or less, in which a strength applied to stretch the film by 6 times is 4 N or more; and a single stretching step of forming a stretched polyvinyl alcohol-based film having a thickness of 10 μm or less by stretching the unstretched polyvinyl alcohol-based film solely, and a thin polarizer manufactured by using the same.