Charging Member Elastic Layer with Syndiotactic Polybutadiene

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Solution Overview

Problem

The use of acrylonitrile butadiene rubber (NBR) as a charging member in electrophotographic apparatuses leads to toner or external additive adhesion and compression set issues, affecting charging performance and image quality.

Innovation Solution

Incorporating butadiene rubber (BR) with 1,2-syndiotactic polybutadiene into the elastic layer, which is irradiated with electron rays to create a crosslinked structure with higher surface hardness and reduced polarity, minimizing adhesion and compression set.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If acrylonitrile butadiene rubber (NBR) is used as the only rubber component in the elastic layer, then the charging member can be formed with good processability, but toner or external additive adheres to the surface of the elastic layer

Engineering Contradiction:
ImproveprocessabilityVSAvoidtoner adhesion
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite rubber material consisting of NBR and BR in a mass ratio of 95:5 to 50:50. This composite material combines the processability benefits of NBR with the low surface energy and anti-adhesion properties of BR, effectively preventing toner adhesion while maintaining manufacturing ease.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If butadiene rubber (BR) is added to the rubber compound including NBR, then toner adhesion is suppressed, but compression set occurs more easily after electron ray irradiation

Engineering Contradiction:
Improvetoner adhesionVSAvoidcompression set resistance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent optimizes the mass ratio of NBR to BR within the range of 95:5 to 50:50, and controls the electron ray irradiation dose and acceleration voltage parameters. By adjusting these parameters, the patent achieves a balance between suppressing toner adhesion and minimizing compression set, as the optimal composition and irradiation conditions enhance crosslinking while maintaining structural integrity.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If the elastic layer is irradiated with electron rays to reduce polarity and suppress adhesion, then toner adhesion is reduced, but compression set is more easily caused when BR is present

Engineering Contradiction:
Improvetoner adhesionVSAvoidcompression set deformation
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The composite rubber material of NBR and BR in specific ratios provides a balanced response to electron ray irradiation. The NBR component contributes to stable crosslinking structure formation that resists compression set, while the BR component provides low surface energy for adhesion suppression, achieving both goals simultaneously through proper material composition.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent controls the electron ray irradiation parameters (acceleration voltage and irradiation dose) to optimize the crosslinking process. By adjusting these parameters within specific ranges, the patent achieves sufficient crosslinking to prevent compression set while maintaining the low polarity surface needed for adhesion suppression.

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

This approach effectively suppresses toner adhesion and compression set, ensuring stable and high-quality electrophotographic image formation by maintaining consistent charging performance.

Implementation Method 1

the surface of a rubber layer which is a crosslinked product of a rubber mixture... irradiating, with electron rays, a surface of the rubber layer

Methodology Applied
Scientific EffectElectron beam irradiation: Electron Beam

Implementation Method 2

a crosslinked structure with higher surface hardness and reduced polarity

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentEP2827197B1Charging member, process cartridge, and electrophotographic device
Publication Date: 2016.07.06 CANON KK
  • EP2827197B1 patent drawingFigure 1~3
  • EP2827197B1 patent drawingFigure 2
  • EP2827197B1 patent drawingFigure 4

AI summary

The present invention provides a charging member having an elastic layer on a surface thereof in which occurrence of compression set is reduced. The charging member includes an electro-conductive support and an elastic layer provided on the support as a surface layer, wherein the elastic layer is a rubber layer made of a crosslinked product of a rubber mixture including acrylonitrile butadiene rubber and polybutadiene, the polybutadiene includes 1,2-syndiotactic polybutadiene, and the elastic layer is formed by irradiating a surface of the rubber layer with electron rays.