Electrophotographic Photosensitive Member Undercoat Layer Process
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Solution Overview
Problem
Existing methods for producing electrophotographic photosensitive members with reduced organic solvent usage and improved long-term stability and uniformity of the undercoat layer are inadequate, as they often result in instability and non-uniformity of the water dispersion liquid and surface finish.
Innovation Solution
A process involving the preparation of an emulsion by dispersing a solution with a hydrophobic solvent in water, where the solubility is 3.0 mass% or less, and incorporating a hydrophilic solvent with solubility of 5.0 mass% or more, to form a stable undercoat layer by heating, which reduces organic solvent usage and enhances long-term stability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a water dispersion liquid containing particles each containing an electron transporting substance is used to form the undercoat layer, then the organic solvent content is reduced, but the stability of the application liquid during long-term storage and the uniformity of the undercoat layer surface deteriorate
Solution Approach 1:
The patent changes the physical-chemical parameters of the application liquid by using an emulsion system with specific solubility characteristics (3.0 mass% or less for the liquid component). This parameter change transforms the unstable particle dispersion into a stable emulsion that maintains uniformity during long-term storage while still reducing organic solvent content.
Solution Approach 2:
The patent creates a composite emulsion system combining hydrophobic and hydrophilic components with specific solubility ratios. This composite structure allows the application liquid to maintain stability during storage while achieving reduced organic solvent content, resolving the contradiction between solvent reduction and stability maintenance.
2Loss of substance
If a water dispersion liquid containing particles each containing an electron transporting substance is used to form the undercoat layer, then the organic solvent content is reduced, but the uniformity of the undercoat layer surface deteriorates
Solution Approach 1:
By changing the solubility parameter of the liquid component to 3.0 mass% or less, the patent achieves a stable emulsion that prevents particle aggregation during application and drying. This parameter control ensures uniform distribution of electron transporting substances, maintaining surface uniformity while reducing organic solvent content.
Solution Approach 2:
The patent introduces a hydrophilic liquid as an intermediary component that mediates between the hydrophobic electron transporting substance particles and the water-based dispersion medium. This intermediary ensures uniform distribution and stable emulsion formation, preventing surface non-uniformity while achieving organic solvent reduction.
3Reliability
If the solubility of the liquid in water is increased to improve emulsion stability, then the long-term storage stability improves, but the organic solvent content increases
Solution Approach 1:
The patent identifies and controls the critical solubility parameter at 3.0 mass% or less, which is the optimal threshold that simultaneously achieves both goals: sufficient emulsion stability for long-term storage and reduced organic solvent content. This precise parameter control resolves the contradiction between stability and solvent reduction.
Solution Approach 2:
The patent applies local quality control by optimizing the solubility characteristic of the specific liquid component in the emulsion system. Rather than uniformly increasing or decreasing all organic components, the patent locally optimizes the liquid phase properties to achieve the desired balance between stability and solvent reduction.
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 achieves a high uniformity of the undercoat layer surface and improves the stability of the application liquid during long-term storage, maintaining emulsified state and reducing oil droplet agglomeration, thus ensuring consistent performance.
Implementation Method 1
heating the coat to form an undercoat layer
Data Source
Figure 1~2
AI summary
Provided is a process for producing an electrophotographic photosensitive member having high uniformity of the surface of its undercoat layer by which the usage of an organic solvent is reduced and the stability of an application liquid for an undercoat layer after its long-term storage is improved in the step of forming the undercoat layer. The process for producing an electrophotographic photosensitive member includes the steps of: preparing a solution containing a liquid whose solubility in water at 25°C and 1 atmosphere is 3.0 mass% or less and an electron transporting substance; preparing an emulsion by dispersing the solution in water; forming a coat of the emulsion on a support; and forming the undercoat layer by heating the coat.