Charge Transporting Layer Emulsion Stability via Segmented Solvents
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Solution Overview
Problem
The existing methods for producing electrophotographic photosensitive members face challenges in achieving long-term stability of the charge transporting layer emulsion, leading to agglomeration and sedimentation due to the coalescence of organic solutions in water, which complicates the reduction of organic solvent usage and maintains high uniformity.
Innovation Solution
A method involving a solution with a hydrophobic first liquid and a hydrophilic second liquid, where the charge transporting substance and binder resin are dissolved, is dispersed in water to form an emulsion, and then heated to form a stable charge transporting layer, reducing organic solvent usage while maintaining emulsion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an organic solution is used to dissolve charge transporting substance and binder resin, then high solubility and uniform coating are achieved, but the emulsion becomes unstable over time causing agglomeration and sedimentation
Solution Approach 1:
The organic solvent system is segmented into two distinct components: a first organic solvent (halogen-based or aromatic) that provides high solubility for charge transporting substance and binder resin, and a second organic solvent (aliphatic hydrocarbon) that is miscible with water and prevents emulsion instability. This segmentation allows each solvent to fulfill its specific function without causing agglomeration or sedimentation over time.
2Reliability
If the thickness of the charge transporting layer is increased to improve durability, then durability is enhanced, but the usage of organic solvent increases
Solution Approach 1:
The invention changes the chemical composition parameters of the solvent system by introducing a second organic solvent (aliphatic hydrocarbon) that is miscible with water. This parameter change allows the formulation to achieve both high solubility of functional materials and reduced overall organic solvent content, enabling thinner coatings with improved durability while minimizing solvent usage.
3Quantity of substance
If halogen-based or aromatic organic solvents are used to ensure high solubility of charge transporting substance and resin, then solubility is improved, but the amount of volatile organic substance increases
Solution Approach 1:
The invention creates a composite solvent system combining a first organic solvent (halogen-based or aromatic) responsible for high solubility with a second organic solvent (aliphatic hydrocarbon) that is miscible with water and has lower volatility concerns. This composite approach allows the formulation to achieve necessary solubility while reducing the proportion of highly volatile components, thereby minimizing harmful emissions.
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 enhances the long-term stability and uniformity of the charge transporting layer, reducing organic solvent consumption and preventing agglomeration, thus improving the production efficiency of electrophotographic photosensitive members.
Implementation Method 1
a first liquid whose solubility in water under 25° C. and 1 atmosphere is 1.0 mass % or less, a second liquid whose solubility in water under 25° C. and 1 atmosphere is 5.0 mass % or more, a charge transporting substance, and a binder resin
Implementation Method 2
preparing an emulsion by dispersing the solution in water
Implementation Method 3
forming the charge transporting layer by heating of the coat
Data Source
AI summary
Provided are a method of producing an electrophotographic photosensitive member, particularly, a method of producing an electrophotographic photosensitive member and an organic device by which, in a method of forming a charge transporting layer, the stability of an application liquid for the layer after long-term storage is improved while the usage of an organic solvent in the application liquid is curtailed, and the layer having high uniformity is formed. The method is a method of producing an electrophotographic photosensitive member which includes a support and a charge transporting layer formed thereon, the method including: preparing a solution including: a first liquid whose solubility in water under 25° C. and 1 atmosphere is 1.0 mass % or less; a second liquid whose solubility in water under 25° C. and 1 atmosphere is 5.0 mass % or more; a charge transporting substance; and a binder resin; preparing an emulsion by dispersing the solution in water; forming a coat for the layer on the support by using the emulsion; and forming the layer by heating of the coat.