Thin Polarizing Plate Manufacturing via Process Film Mediator
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Solution Overview
Problem
The existing methods for manufacturing single-faced thin polarizing plates face challenges in preventing contamination and breakage, especially when using thin polyvinyl alcohol-based films with low rigidity, as the adhesive composition often contaminates the pressing roll and the films are prone to breakage due to modulus differences.
Innovation Solution
A method involving the supply of a process film to one surface of a thin polarizer, a protection film to the other, forming an adhesive layer, and pressing with a pair of pressing units, while ensuring a stripping force of 1.0 N or less, and optionally forming a protection layer using radical- or cation-curable compositions to achieve a modulus of 500 MPa to 6000 MPa and a thickness of 0.5 µm to 10 µm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive composition is applied in a width wider than the polarizer width to prevent non-attachment surfaces, then attachment reliability is improved, but contamination of the pressing roll occurs
Solution Approach 1:
A process film is introduced as an intermediary layer between the polarizer and the pressing roll. This process film receives the adhesive composition that would otherwise contaminate the pressing roll, while still allowing the polarizer to achieve proper attachment. The process film is subsequently removed, leaving the polarizer properly attached without contamination issues.
Solution Approach 2:
The system is segmented into distinct functional layers: the polarizer, the process film, and the pressing roll. By separating the functions of attachment and pressing, the contamination problem is resolved. The process film handles the adhesive composition while the pressing roll handles only the mechanical pressing function.
2Length of moving object
If thin PVA-based film with thickness of 50 μm or less is used to reduce display device thickness, then thickness is reduced, but the film is easily broken due to low rigidity and modulus difference
Solution Approach 1:
The process film serves as a cushioning layer applied beforehand to the thin PVA-based film. This process film provides mechanical support and distributes applied modulus, preventing the thin film from breaking during handling and processing. The process film is removed after serving its protective function.
Solution Approach 2:
A process film with appropriate mechanical properties is used as a flexible protective shell during the manufacturing process. This thin film provides the necessary support to the even thinner PVA-based film without significantly increasing the overall thickness, and can be easily removed after processing.
3Object-generated harmful factors
If process film with large width difference from polarizer is used to prevent contamination, then contamination is prevented, but device complexity increases
Solution Approach 1:
The process film is designed with specific parameter ranges: thickness of 10-100 μm, width exceeding the polarizer width by 10-50 mm, and surface roughness of 0.1-10 μm. These parameter optimizations allow the process film to effectively prevent contamination while minimizing the increase in device complexity and facilitating easy integration into existing manufacturing processes.
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 method allows for the efficient production of thin polarizing plates with a thickness of 30 µm to 140 µm, preventing contamination and breakage, while maintaining high workability and productivity through a continuous roll-to-roll process.
Implementation Method 1
forming an adhesive layer by supplying an adhesive composition between the polarizer and the protection film
Implementation Method 2
forming a protection layer using radical- or cation-curable compositions
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a method for manufacturing a single-faced thin polarizing plate, including: supplying a process film to one surface of a polarizer having a thickness of 50 µm or less; supplying a protection film to the other surface of the polarizer; forming an adhesive layer by supplying an adhesive composition between the polarizer and the protection film; pressing a laminate of the process film/the polarizer/the protection film by disposing a pair of pressing units on a surface of each of the process film and the protection film; and stripping the process film, in which stripping force between the polarizer and the process film is 1.0 N or less.