Undercoat Layer Butyral Resin Control for Charge Retention

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Solution Overview

Problem

Electrophotographic photoreceptors with undercoat layers containing more than 5 mass % butyral resin suffer from inadequate charge-retaining properties due to minority hole migration, leading to residual potential decay.

Innovation Solution

An electrophotographic photoreceptor with a conductive substrate, an undercoat layer formed from a cured product containing a reactive group-containing triarylamine compound, a curing agent, and an electron transport material, with a butyral resin content of 0 to 5 mass % or less, which enhances charge retention by suppressing hole migration and improving film stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the undercoat layer contains more than 5 mass % butyral resin, then the film forming property is improved, but the charge-retaining property deteriorates due to hole migration

Engineering Contradiction:

Improvefilm forming propertyVSAvoidcharge-retaining property

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the undercoat layer by incorporating specific electron transporting substances (compounds of formulas (1) and (2)) and controlling the butyral resin content to 5 mass % or less. This parameter optimization resolves the contradiction by achieving adequate film formation while suppressing hole migration through the electron transporting substances, thereby maintaining charge-retaining property.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the undercoat layer contains more than 5 mass % butyral resin, then the film stability is improved, but the residual potential increases due to charge retention decay

Engineering Contradiction:

Improvefilm stabilityVSAvoidresidual potential

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The patent optimizes the composition parameters by limiting butyral resin to 5 mass % or less and incorporating specific electron transporting substances (formulas (1) and (2)). This parameter change achieves the desired balance: the electron transporting substances provide sufficient film stability while reducing hole migration, thereby maintaining lower residual potential levels.

Inventive Principle:

Principle #35Parameter changes

3Speed

If electron transport material is used in the undercoat layer, then electron transport property is improved, but charge-retaining property deteriorates due to hole migration

Engineering Contradiction:

Improveelectron transport propertyVSAvoidcharge-retaining property

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies local quality by using different types of electron transporting substances in different layers. The undercoat layer contains specific compounds (formulas (1) and (2)) with balanced electron transport and charge retention properties, while the charge generation layer contains different electron transporting substances optimized for charge generation. This layered differentiation resolves the contradiction by optimizing each layer's composition for its specific function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the chemical structure parameters of the electron transporting substances by specifying compounds of formulas (1) and (2) in the undercoat layer. These structural parameters provide adequate electron transport capability while simultaneously suppressing hole migration, thereby maintaining charge-retaining property that conventional electron transport materials cannot achieve alone.

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 solution significantly improves charge-retaining properties and reduces residual potential, maintaining stability across varying environmental conditions without compromising electron transport efficiency.

Implementation Method 1

the undercoat layer is formed of a cured product of a composition that contains a reactive group-containing triarylamine compound, a curing agent, and an electron transport material

Methodology Applied

Scientific EffectCuring reaction: Chemical Bonding

Implementation Method 2

the undercoat layer is formed of a cured product of a composition that contains a reactive group-containing triarylamine compound, a curing agent, and an electron transport material

Methodology Applied

Scientific EffectElectron transport: Conduction (electrical)

Data Source

PatentUS20230251585A1Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Publication Date: 2023.08.10 FUJIFILM BUSINESS INNOVATION CORP

AI summary

An electrophotographic photoreceptor includes a conductive substrate, an undercoat layer on the conductive substrate, and a photosensitive layer on the undercoat layer, in which the undercoat layer is formed of a cured product of a composition that contains a reactive group-containing triarylamine compound, a curing agent, and an electron transport material and that has a butyral resin content of 0 mass % or more and 5 mass % or less relative to all solid components in the undercoat layer.