Photosensitive Member Undercoat Polymer for Stable Mass Printing
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Solution Overview
Problem
Existing electrophotographic photosensitive members experience potential fluctuations during mass printing and high-speed printing due to insufficient electron mobility and charge retention, leading to reduced image quality over repeated use.
Innovation Solution
Incorporating a specific polymer with structural units in the undercoat layer to improve electron mobility, using polymers with structural units represented by formulas (1) and (2), which help distribute perylene imide and naphthalene imide molecules uniformly, thereby suppressing potential fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photosensitive members are used, then image bearing members can be formed, but bacterial adhesion and contamination occur on the surface
Solution Approach 1:
The patent applies porous silicon oxide particles to the undercoat layer surface, creating a porous structure with average pore diameter of 0.01 to 2 μm. This porous structure physically prevents bacterial adhesion by eliminating smooth surfaces where bacteria can attach, while maintaining the electrical insulation function. The porous SiO2 particles are formed by adding a silane compound and performing heat treatment, creating a hierarchical porous structure that resolves the contradiction between maintaining surface functionality and preventing contamination.
Solution Approach 2:
The patent creates a composite undercoat layer combining polymer material with silicon oxide particles (SiO2 content 1-50 wt%). This composite structure integrates the electrical insulation properties of the polymer with the anti-adhesion properties of the porous SiO2 particles. The composite material approach allows simultaneous achievement of electrical insulation necessary for electrophotographic operation and contamination resistance through the porous particle structure.
2Manufacturing precision
If the photosensitive layer is made highly sensitive, then image quality improves, but white spots appear in the developed image
Solution Approach 1:
The patent applies different materials and structures to different layers: the undercoat layer receives porous SiO2 particles for anti-contamination, while the photosensitive layer uses specific polymer compounds (carboxylic acid groups with pKa 3.5-6.5) to control surface properties. This local differentiation allows the photosensitive layer to maintain high sensitivity for image quality while the undercoat layer prevents bacterial adhesion, and the specific polymer chemistry prevents white spot formation during development.
Solution Approach 2:
The patent specifies precise chemical parameters for the photosensitive layer polymer, particularly carboxylic acid groups with pKa values between 3.5 and 6.5. This parameter control optimizes the surface charge characteristics and electrostatic properties, enabling high sensitivity for good image quality while preventing excessive charge buildup that would cause white spots during the development process. The pKa parameter optimization resolves the contradiction between sensitivity and defect prevention.
3Manufacturing precision
If a polymer with carboxylic acid groups is used in the photosensitive layer, then sensitivity improves, but non-image portions are not sufficiently charged
Solution Approach 1:
The patent optimizes the pKa parameter of carboxylic acid groups in the photosensitive layer polymer to be between 3.5 and 6.5, and controls the polymer content in the undercoat layer at 5-50 wt%. These parameter adjustments balance the surface charge characteristics: the optimized pKa ensures sufficient sensitivity through appropriate surface charge density while preventing excessive charge that would cause non-uniform charging in non-image portions. The dual-parameter optimization resolves the contradiction between sensitivity and charging uniformity.
Solution Approach 2:
The patent differentiates the composition between layers: the photosensitive layer contains polymer with carboxylic acid groups for sensitivity, while the undercoat layer contains 5-50 wt% of this polymer to modulate charging properties. This local quality differentiation allows the photosensitive layer to achieve high sensitivity while the undercoat layer's polymer content controls the overall charging uniformity, preventing non-image portion charging issues while maintaining image quality.
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 solution effectively stabilizes image quality by enhancing electron mobility and reducing potential fluctuations, ensuring consistent image density during repeated use.
Implementation Method 1
the undercoat layer comprises porous silicon oxide particles having an average pore diameter of 0.01 to 2 μm
Implementation Method 2
a photosensitive layer
Data Source
Figure 1
Figure 2
AI summary
Provided is an electrophotographic photosensitive member including in this order: a support; an undercoat layer; and a photosensitive layer, wherein the undercoat layer comprises at least one kind of polymer selected from the group consisting of: a polymer having a structural unit represented by the following formula (1); and a polymer having a structural unit represented by the following formula (2).