Charge Transporting Layer Coating Fluid Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The stability of emulsion-type charge transporting layer coating fluids used in electrophotographic photosensitive members degrades over time due to coalescence of oil droplets, leading to agglomeration and reduced uniformity in the charge transporting layer.
Innovation Solution
A process involving the formation of a liquid dispersion with particles containing charge transporting materials and binder resins dispersed in an aqueous medium, where the mixture is heated above the melting point of the charge transporting material to form a stable charge transporting layer, reducing the need for organic solvents and preventing coalescence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If emulsion type coating fluid is prepared by dissolving charge transporting materials in organic solvent and forming oil droplets in water, then the quantity of organic solvent can be reduced, but the coating fluid becomes unstable over time due to coalescence of oil droplets
Solution Approach 1:
The invention changes the physical state of charge transporting materials from dissolved state in organic solvent to dispersed particle state in aqueous medium. By controlling particle size (0.1-10 μm) and using particles instead of oil droplets, the system achieves long-term stability while reducing organic solvent content to 30 mass% or less.
Solution Approach 2:
The invention replaces the unstable emulsion type coating fluid with a stable particle dispersion system. The particle-based approach eliminates the coalescence issue inherent in emulsion systems, providing a durable, long-lasting coating fluid that maintains stability during storage and application.
2Ease of manufacture
If charge transporting materials are dissolved in large quantity of organic solvent to form coating fluid, then the coating fluid can be prepared easily, but the quantity of organic solvent used increases significantly
Solution Approach 1:
The invention changes the preparation method from dissolving materials in organic solvent to dispersing pre-formed particles in aqueous medium. This approach reduces organic solvent content to 30 mass% or less while maintaining ease of manufacture through simple mixing and coating processes.
Solution Approach 2:
The invention extracts the organic solvent from the coating fluid system, replacing it with an aqueous dispersion medium. By using particles of charge transporting materials that can be dispersed in water or aqueous solutions, the system eliminates the need for large quantities of organic solvent while maintaining coating fluid functionality.
3Object-generated harmful factors
If oil droplets are formed in water to reduce organic solvent content, then volatile substances are reduced, but the oil droplets coalesce over time causing agglomeration and reduced uniformity
Solution Approach 1:
The invention replaces unstable emulsion type coating fluids with stable particle dispersion systems. By using solid particles instead of liquid oil droplets, the system eliminates coalescence and maintains uniformity throughout storage and application, ensuring consistent coating quality.
Solution Approach 2:
The invention changes the dispersion medium from water-based emulsion to aqueous particle suspension. By controlling particle size (0.1-10 μm) and using appropriate aqueous dispersion media, the system prevents agglomeration and maintains uniform distribution, eliminating the harmful effects of volatile substances without sacrificing coating uniformity.
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 enhances the long-term stability and uniformity of the charge transporting layer, maintaining dispersion stability and preventing agglomeration, even after extended storage, thereby improving the manufacturing process and performance of electrophotographic photosensitive members.
Implementation Method 1
heating the coat at a temperature not less than the melting point of the charge transporting material to form a charge transporting layer
Implementation Method 2
heating the coat at a temperature not less than the melting point of the charge transporting material
Implementation Method 3
the binder resin being soluble in a molten product of the charge transporting material
Data Source
Figure 1
AI summary
In a process for producing an electrophotographic photosensitive member, in particular, a process of forming a charge transporting layer, a production process is provided by which the stability of a charge transporting layer coating fluid even after its storage for a long time is improved so as to form a coat for a charge transporting layer having a high uniformity. In a process for producing an electrophotographic photosensitive member having a charge transporting layer on a support, a production process is used in which a coat of (i) a liquid dispersion comprised of particles containing a charge transporting material, particles containing a binder resin, and an aqueous dispersion medium, or (ii) a liquid dispersion comprised of particles containing both a charge transporting material and a binder resin, and an aqueous dispersion medium, is formed on the support and then the coat is heated at a temperature not less than the melting point of the charge transporting material to form the charge transporting layer.