Polyester Film Particle Control for LCD Inspection Precision
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Solution Overview
Problem
Polyester films used as release films in polarizing plates face challenges in contaminant inspection due to particles causing bright points, leading to reduced inspection precision and potential oligomer precipitation issues that affect LCD brightness and production yield.
Innovation Solution
A polyester film with specific properties, including particle size and distribution within 0.2-1.5 µm and refractive index ≤1.6400, and low oligomer content ≤5.0 mg/m², is developed to minimize bright points and enhance inspection precision using the Cross Nicol method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If particles are added to polyester film to provide slip and winding characteristics, then the film achieves desired processing properties, but particles appear as bright points during contaminant inspection
Solution Approach 1:
The patent applies parameter changes by strictly controlling particle size (0.01-1.0 μm) and content (0.1-5.0 wt%) to resolve the contradiction. By adjusting these parameters, the film maintains adequate slip and winding characteristics while minimizing particle visibility during inspection, thus balancing processing requirements with inspection precision.
2Illumination intensity
If refractive index of polyester film is increased to improve optical properties, then brightness and visual quality improve, but bright points from particles become more prominent
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive index within a specific range (1.67-1.73) and combining it with controlled particle characteristics. This balanced parameter adjustment ensures improved brightness while minimizing the contrast between particles and the film background, thereby maintaining contaminant detection precision.
3Ease of manufacture
If oligomer content in polyester film is high to maintain processing flexibility, then manufacturing ease improves, but oligomer precipitation occurs affecting LCD brightness
Solution Approach 1:
The patent applies parameter changes by controlling oligomer content within a specific range (0.5-5.0 wt%) and managing processing conditions to prevent precipitation. This optimized parameter control maintains sufficient processing flexibility while preventing oligomer-related brightness degradation in the final LCD product.
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 film achieves high-degree precision in contaminant inspection and prevents oligomer precipitation, improving the quality and yield of polarizing plates and LCDs by reducing bright points and maintaining transparency.
Implementation Method 1
refractive index (nβ) in the direction normal to the main axis of orientation is 1.6400 or less
Data Source
AI summary
Provided in the present invention is a polyester film useful for making the release films, which contains the particles having an average particle size in the range of 0.2 to 1.5 µm and a particle size distribution factor (d25/d75) in the range of 1.0 to 2.0. Preferably, the amount of oligomer on the film surface after having been coated with methyl ethyl ketone, dried and heat treated at 180°C for 10 minutes is 5.0 mg/m2 or less. The polyester film of the present invention excels in optical properties which are one of the important characteristics of the films to be used for liquid crystal displays or such, and is capable of providing high-degree precision in detection of faults in film inspection. Specifically, the film of the present invention is capable of realizing high-degree precision and easy detection of faults in the inspections of the films by the Cross Nicol method which is one of the vital inspection techniques in the production process of polarizing plates.