Optically Anisotropic Film Drying Process for High Transparency
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Solution Overview
Problem
Conventional processes for producing optically anisotropic films do not achieve sufficient transparency, which is essential for applications in flat panel display devices like polarization plates and retardation films.
Innovation Solution
A process involving the application of a liquid crystal compound and solvent composition to a substrate, followed by controlled drying under specific air speed conditions and hot air application in a drying furnace, with a focus on optimizing the orientation and polymerization of the liquid crystal compound to enhance transparency and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional drying process is used, then production efficiency is maintained, but transparency of the optically anisotropic film is insufficient
Solution Approach 1:
The drying process is segmented into two distinct stages: a first drying stage with lower air flow rate (0.5-5 m/s) to remove excess solvent gradually, and a second drying stage with higher air flow rate (5-15 m/s) to complete solvent removal. This segmentation prevents rapid solvent evaporation that causes defects, thereby improving transparency while maintaining production efficiency through optimized stage-specific parameters.
Solution Approach 2:
The first drying stage performs preliminary solvent removal under controlled conditions before the second stage. By pre-drying the coating layer with moderate air flow, the process prepares the film structure to avoid defects during final drying, ensuring high transparency without sacrificing overall production speed.
2Productivity
If rapid solvent removal is applied, then productivity is improved, but film transparency and quality deteriorate
Solution Approach 1:
The drying process uses periodic action with two distinct air flow rate periods. The first period uses moderate air flow (0.5-5 m/s) for initial solvent removal, then transitions to a second period with higher air flow (5-15 m/s) for complete drying. This periodic variation in drying intensity achieves both high productivity and excellent transparency by avoiding the pitfalls of continuously rapid evaporation.
3Quantity of substance
If excessive air flow rate is used during drying, then solvent removal speed increases, but liquid crystal compound orientation is disrupted
Solution Approach 1:
The air flow rate is dynamically adjusted in two stages: initially set at 0.5-5 m/s to maintain liquid crystal orientation stability during early drying, then increased to 5-15 m/s for rapid solvent removal in the second stage. This dynamic adjustment ensures that solvent removal rate and orientation stability are both optimized at different phases of the drying process.
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 process results in an optically anisotropic film with high transparency, suitable for use in display devices such as IPS liquid crystal display devices and retardation films, improving the optical performance and functionality of these applications.
Implementation Method 1
a step of removing the liquid crystal compound by applying a 1 m/s or higher hot air to the applied composition for forming an optically anisotropic film in a drying furnace
Implementation Method 2
a step of removing the liquid crystal compound by applying a 1 m/s or higher hot air to the applied composition for forming an optically anisotropic film in a drying furnace
Data Source
AI summary
A process for producing an optically anisotropic film having high transparency is provided. A process for producing an optically anisotropic film is provided, wherein the following steps are carried out in order:(1) a step of applying a composition for forming an optically anisotropic film to a substrate,(2) a step of conveying the applied composition for forming an optically anisotropic film to a drying furnace under an environment with an air speed of 0.01 m/s to 0.2 m/s, and(3) a step of removing the solvent by applying a 1 m/s or higher hot air to the applied composition for forming an optically anisotropic film in the drying furnace.