Polarizing Plate Bonding Layer Modulus Control
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Solution Overview
Problem
The existing methods for manufacturing polarizing plates with a polarizer, optical rotatory layer, and brightness enhancement film using a transfer method often result in deteriorated appearance properties due to low rigidity and ease of wrinkles and bubbles formation, which affects the productivity and quality of the polarizing plates.
Innovation Solution
Adjusting the storage elastic modulus of the bonding layers between the polarizer and optical rotatory layer, and between the optical rotatory layer and the brightness enhancement film to specific ranges, along with using a twisted liquid crystal compound aligned in a helical axis, to enhance the rigidity and reduce haze, thereby improving the appearance properties of the polarizing plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a transfer method is used to manufacture a polarizing plate including a polarizer, optical rotatory layer, and brightness enhancement film, then the thickness of each device can be reduced, but the appearance properties deteriorate due to low rigidity and ease of wrinkles and bubbles formation
Solution Approach 1:
The patent changes the physical parameter of the bonding layer by controlling its storage elastic modulus to be within a specific range (10^4 to 10^6 dynes/cm²). This parameter optimization allows the bonding layer to provide sufficient rigidity during the transfer process, preventing wrinkles and bubbles, while still enabling the thin-film structure to achieve reduced overall device thickness.
2Manufacturing precision
If the storage elastic modulus of the bonding layer is too low, then the bonding layer is too soft and causes wrinkles and bubbles, but if it is too high, then the bonding layer is too rigid and causes difficulty in bonding and increased internal stress
Solution Approach 1:
The patent identifies and controls the storage elastic modulus of the bonding layer as a critical parameter, setting it within the optimal range of 10^4 to 10^6 dynes/cm². This parameter optimization balances the competing requirements: providing enough rigidity to prevent wrinkles and bubbles during transfer, while maintaining sufficient flexibility for easy bonding and minimizing internal stress.
Solution Approach 2:
The bonding layer is formulated as a composite material comprising a polymer component and a crosslinking agent. This composite structure allows the bonding layer to achieve the desired storage elastic modulus through controlled crosslinking, providing both the rigidity needed for wrinkle prevention and the bonding capability required for easy manufacturing.
3Volume of moving object
If the optical rotatory layer has low rigidity, then it is easy to manufacture with thin thickness, but it causes ease of wrinkles and bubbles formation during bonding
Solution Approach 1:
The patent introduces a bonding layer as an intermediary between the optical rotatory layer and the polarizer. This bonding layer acts as a mediator that provides the necessary mechanical support and rigidity during the bonding process, preventing wrinkles and bubbles from forming in the thin optical rotatory layer, while still allowing the overall structure to maintain reduced thickness.
Solution Approach 2:
The patent optimizes the storage elastic modulus of the bonding layer to within the range of 10^4 to 10^6 dynes/cm². This parameter control ensures that the bonding layer has sufficient rigidity to support the thin optical rotatory layer during bonding and prevent defects, while maintaining the overall thin-film structure for reduced device thickness.
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 method allows for the easy manufacturing of polarizing plates with excellent appearance properties, reducing wrinkles and bubbles, and improving the in-plane uniformity and brightness of the polarizing plates, which are essential for liquid crystal display devices.
Implementation Method 1
an optical rotatory layer which has a film thickness of 10 μm or less and rotates a polarization axis of linearly polarized light
Implementation Method 2
bonding the optical rotatory layer of the temporary support with an optical rotatory layer and a polarizer through a curable adhesive layer and then curing the curable adhesive layer to form a first bonding layer
Data Source
AI summary
A method for manufacturing a polarizing plate having excellent appearance properties and including a polarizer, an optical rotatory layer, and a brightness enhancement film, a polarizing plate, and a liquid crystal display device including the polarizing plate, are described. The method includes forming an optical rotatory layer, which has a film thickness of 1 to 10 μm and rotates a polarization axis of linearly polarized light, on a temporary support to manufacture a temporary support with an optical rotatory layer; bonding the optical rotatory layer of the temporary support with an optical rotatory layer and polarizer through a curable adhesive layer, and curing the curable adhesive layer to form a first bonding layer having a storage elastic modulus of 2 to 1500 MPa; peeling off the temporary support from the laminate; and bonding the optical rotatory layer of the laminate and a brightness enhancement film through a second bonding layer.