Electrophotographic Photosensitive Member Uniform Coating

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing electrophotographic photosensitive members exhibit differences in image density along the axial direction due to variations in the contact time with the charge transport layer forming coating liquid during dip coating, leading to inconsistencies in sensitivity and image quality.

Innovation Solution

Incorporating a vinyl copolymer with a structural unit containing a chlorine atom, an acyloxy group, and an aromatic polycarboxylic acid structure, where the proportion of the chlorine-containing component is 80% or more and the aromatic polycarboxylic acid component is 0.5% or more by mass, to reduce the solubility of the vinyl copolymer in the solvent and enhance the dispersibility of the charge generating material, thereby minimizing sensitivity differences and image density variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If dip coating is used to apply charge transport layer forming coating liquid, then the coating process is simple and efficient, but the contact time varies between upper and lower ends causing differences in sensitivity and image density

Engineering Contradiction:

Improvecoating efficiencyVSAvoidimage density uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent modifies the chemical composition parameters of the binder resin by specifying functional group proportions (carboxyl groups: 0.5-5 mmol/g, hydroxyl groups: 0.5-5 mmol/g) to control the resin's interaction with the coating liquid, thereby reducing solubility differences and achieving uniform image density while maintaining dip coating efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite binder resin system combining multiple functional groups (carboxyl, hydroxyl, and other polar groups) to create a material that provides both adequate solubility for coating application and sufficient stability to prevent excessive dissolution during the dip coating process, resolving the contradiction between coating efficiency and image uniformity

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If the vinyl copolymer has high solubility in the coating liquid, then the coating application is easy, but the sensitivity differences between ends increase due to varying contact times

Engineering Contradiction:

Improvecoating applicabilityVSAvoidsensitivity consistency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent precisely controls the solubility parameter of the binder resin by limiting functional group proportions (carboxyl: 0.5-5 mmol/g, hydroxyl: 0.5-5 mmol/g), creating an optimal balance where the resin is sufficiently soluble for easy coating application but stable enough to maintain sensitivity consistency across different contact times

Inventive Principle:

Principle #35Parameter changes

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 proposed solution effectively reduces the difference in image density along the axial direction while maintaining high sensitivity by stabilizing the vinyl copolymer and enhancing the dispersibility of the charge generating material, even with varying contact times during the dip coating process.

Implementation Method 1

the solvent included in the charge transport layer forming coating liquid may dissolve part of the vinyl copolymer included in the charge generation layer

Methodology Applied

Scientific EffectSolubility reduction through molecular structure:

Implementation Method 2

In dip coating, a conductive support including a charge generation layer disposed on the outer peripheral surface thereof is dipped into and withdrawn from a charge transport layer forming coating liquid

Methodology Applied

Scientific EffectDip coating deposition: Deposition (physical)

Data Source

PatentUS11714359B2Electrophotographic photosensitive member, process cartridge, and image forming apparatus

Publication Date: 2023.08.01 FUJIFILM BUSINESS INNOVATION CORP

AI summary

An electrophotographic photosensitive member includes: a conductive support; a charge generation layer disposed on the conductive support, the charge generation layer including a charge generating material and a vinyl copolymer, the vinyl copolymer including a structural unit including a chlorine atom, a structural unit including an acyloxy group, and a structural unit including an aromatic polycarboxylic acid structure, a proportion of the structural unit including a chlorine atom to all the structural units being 80% by mass or more, a proportion of the structural unit including an aromatic polycarboxylic acid structure to all the structural units being 0.5% by mass or more; and a charge transport layer disposed on the charge generation layer, the charge transport layer including a charge transporting material and a binder resin.