Thin Polarizing Plate Substrate Stretching Control
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Solution Overview
Problem
Existing methods for producing thin polarizing plates often result in phase differences in the substrate film after stretching, leading to unnecessary material waste and the need for separate protective films, and face challenges in producing wide-width polarizers due to difficulties in handling large substrate films.
Innovation Solution
A layered body comprising a polarizer material film and a substrate film, where the polarizer material film is stretched at a specific ratio and the substrate film at a smaller ratio, with a controlled angle between their stretching directions, allowing the substrate film to be used as a protective film and enabling efficient production of thin polarizing plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a thin polarizer is produced from polyvinyl alcohol by a prior art production method, then the thickness of the polarizer is reduced, but melt-breakage of the polarizer frequently occurs
Solution Approach 1:
The patent uses a composite structure consisting of a polyvinyl alcohol-based film (polarizer) and a substrate film. The substrate film provides mechanical support during the stretching process, preventing melt-breakage of the thin polarizer while allowing the final product to achieve the desired thin thickness.
Solution Approach 2:
The substrate film is prepared in advance and the polyvinyl alcohol-based film is attached to it before stretching. This preliminary arrangement ensures that the thin polarizer has sufficient mechanical strength during the stretching process to prevent rupture.
2Productivity
If a layered body is obtained by attaching an unstretched polyvinyl alcohol-based film to an unstretched high-density polyethylene substrate film and then subjected to stretching treatment, then the polarizer can be produced, but phase difference is generated in the substrate film after stretching at high stretching ratio
Solution Approach 1:
The patent changes the material parameters of the substrate film by selecting specific resin types (cycloolefin resin, amorphous polyester resin, polyolefin resin, or acrylic resin) with appropriate physical properties. These material parameter changes allow the substrate film to withstand high stretching ratios while minimizing phase difference generation.
Solution Approach 2:
The patent applies different quality requirements to different parts of the system: the polyvinyl alcohol-based film requires high stretching ratio for polarization, while the substrate film is selected with specific resin properties to maintain low phase difference under the same stretching conditions.
3Area of stationary object
If the width of the substrate film is made extremely large to obtain a thin polarizing plate with sufficiently wide width, then the polarizer width is sufficient, but difficulty in production arises
Solution Approach 1:
The patent segments the production process into: (1) attaching the polyvinyl alcohol-based film to a manageable-sized substrate film, and (2) performing stretching treatment that simultaneously achieves both width expansion and polarization. This segmentation allows production to proceed with smaller, more manageable substrate films rather than requiring extremely wide films from the start.
Solution Approach 2:
The patent uses stretching treatment to transform the substrate film in the width dimension, converting a smaller initial width into the desired large final width through controlled deformation. This dimensional transformation approach avoids the need to handle and process extremely wide films directly.
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 minimizes phase differences in the substrate film, prevents rupture, and allows the substrate film to be used as a protective film, facilitating the efficient production of thin polarizing plates without the need for separate protective films and reducing warping.
Implementation Method 1
a polarizer material film that is a product of stretching in one or more directions, and a substrate film provided on the polarizer material film, the substrate film being a product of stretching in one or more directions
Data Source
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Figure 5
AI summary
A layered body including a polarizer material film that is a product of stretching in one or more directions, and a substrate film provided on the polarizer material film, the substrate film being a product of stretching in one or more directions, wherein a stretching ratio X of the polarizer material film is 1.5 or more and 5.5 or less, a thickness T2 is 20 µm or less, the thickness T2 being a thickness of the polarizer material film as a result of free end uniaxial stretching of the layered body at a stretching ratio 6.0/X, an angle θ2 formed by a stretching direction of the polarizer material film and a stretching direction of the substrate film is less than 1°, and a stretching ratio Y of the substrate film is smaller than the stretching ratio X of the polarizer material film.