Electrophotographic Photoconductor Coating Uniformity
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Solution Overview
Problem
The existing methods for manufacturing electrophotographic photoconductors face challenges in achieving uniform film thickness due to temperature differences between the support and coating liquids during the immersion-coating process, leading to defects such as foaming and variations in viscosity, which hinder the uniformity of the charge transport layer on top of the charge generating layer.
Innovation Solution
A method involving the steps of immersing a cylindrical electrically-conductive support in a charge generating layer coating liquid, heat drying, cooling, and then immersing it in a charge transport layer coating liquid while maintaining a controlled temperature difference and retaining gas inside the support to form a uniform charge transport layer, using a solvent with a boiling point between 34°C and 85°C, and ensuring specific surface temperature conditions to minimize viscosity changes and prevent foaming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the support is heat dried before immersion coating, then the coating liquid can be applied, but the temperature difference between support and coating liquid causes large viscosity change and poor film thickness uniformity
Solution Approach 1:
The support is pre-heated to approximately 40°C before immersion coating with coating liquid at 25°C. This preliminary temperature adjustment reduces the temperature difference between support and coating liquid, minimizing viscosity changes during coating and achieving uniform film thickness of 10 μm or less across the photosensitive layer.
2Manufacturing precision
If the temperature difference between support and coating liquid is made small, then film thickness uniformity improves, but air inside support is released causing foaming defects
Solution Approach 1:
The support temperature is controlled to be 40°C (within 5-60°C range) before immersion coating, while coating liquid temperature is maintained at 25°C. This parameter optimization creates a moderate temperature difference that prevents excessive viscosity changes and avoids air release/foaming, achieving both uniform film thickness and defect-free coating.
3Productivity
If multiple coating liquid layers are stacked continuously, then production efficiency increases, but temperature accumulation causes large viscosity change and poor coating uniformity
Solution Approach 1:
In continuous multi-layer coating production, the support temperature is monitored and controlled to remain at approximately 40°C before each immersion coating step. This feedback control ensures consistent temperature conditions across multiple coating cycles, maintaining coating liquid viscosity stability and achieving uniform film thickness (10 μm or less) for each layer while sustaining high production efficiency.
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 results in a higher uniformity of film thickness for the charge transport layer, improving the overall image performance of electrophotographic photoconductors by maintaining a consistent surface temperature and reducing solvent volatilization, thereby enhancing production efficiency and reducing defects.
Implementation Method 1
heat drying the electrically-conductive support coated with the charge generating layer coating liquid to form the charge generating layer
Implementation Method 2
subjecting the electrically-conductive support on which the charge generating layer has been formed to immersion-coating with a charge transport layer coating liquid to form a coating film of the charge transport layer coating liquid on the charge generating layer
Implementation Method 3
drying the coating film of the charge transport layer coating liquid to form the charge transport layer
Data Source
AI summary
A method for manufacturing an electrophotographic photoconductor including a charge generating layer and a charge transport layer in this order on a cylindrical electrically-conductive support including the steps of: (i) immersing the support in a charge generating layer coating liquid, (ii) pulling the support out of the coating liquid, (iii) heat drying the support coated with the coating liquid to form the charge generating layer, (iv) cooling the charge generating layer, and (v) immersing the support on which the charge generating layer has been formed in a charge transport layer coating liquid while retaining gas inside of the support. The charge transport layer coating liquid contains a solvent having a boiling point of 34° C. or more and 85° C. or less, and the step (v) satisfies two specific conditions.