Electrophotographic Roller Matrix-Domain Structure for Contamination Control

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Solution Overview

Problem

Existing electrophotographic transfer rollers experience contamination issues due to bleeding of low molecular rubber components from the rubber layer, leading to attachment of components on other members, especially when in contact for extended periods.

Innovation Solution

A roller with an electro-conductive mandrel and a surface layer comprising a vulcanized product of acrylonitrile-butadiene rubber and hydrin rubber, featuring a matrix-domain structure with a specific ethylene oxide content and spin-spin relaxation time, which inhibits impurities from bleeding to the surface, thereby reducing contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rubber layer is used in the transfer roller, then flexibility and electro-conductivity are maintained, but low molecular rubber components bleed to the surface causing contamination of other members

Engineering Contradiction:

Improveelectro-conductivityVSAvoidcontamination

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The rubber layer is segmented into a matrix phase (acrylonitrile-butadiene rubber) and dispersed domain phases (hydrin rubber with ethylene oxide). This segmentation prevents low molecular components from migrating to the surface by confining them within the matrix structure, while maintaining electro-conductivity through the acrylonitrile-butadiene rubber matrix.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A composite rubber composition is used comprising acrylonitrile-butadiene rubber as the matrix and hydrin rubber containing ethylene oxide as dispersed domains. This composite structure combines the electro-conductive properties of acrylonitrile-butadiene rubber with the contamination-resistant properties of ethylene oxide-containing hydrin rubber, achieving both high electro-conductivity and low contamination.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the rubber composition is optimized for high electro-conductivity, then transfer performance is improved, but contamination of the image bearing member increases

Engineering Contradiction:

Improvetransfer performanceVSAvoidcontamination

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

Different regions of the rubber composition have different functions: the matrix phase (acrylonitrile-butadiene rubber) provides electro-conductivity for efficient toner transfer, while the dispersed domain phase (hydrin rubber with ethylene oxide) provides contamination resistance. This local differentiation of properties allows simultaneous optimization of transfer performance and contamination resistance.

Inventive Principle:

Principle #3Local quality

3Productivity

If the roller operates for extended periods, then production efficiency is maintained, but contamination of other members increases due to component bleeding

Engineering Contradiction:

Improvecontinuous operation capabilityVSAvoidcontamination

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The ethylene oxide-containing hydrin rubber domains are pre-distributed within the matrix before operation begins. This preliminary structuring prevents low molecular components from migrating to the surface during extended operation, maintaining low contamination levels throughout continuous production without sacrificing productivity.

Inventive Principle:

Principle #10Preliminary action

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 reduces contamination and maintains high electro-conductivity, ensuring improved transfer of toner images and reduced contamination of the image bearing member, while maintaining flexibility and electro-conductivity.

Implementation Method 1

the vulcanized product has a matrix-domain structure having a sea phase and an island phase, the sea phase containing a vulcanized acrylonitrile-butadiene rubber, and the island phase containing a vulcanized hydrin rubber

Methodology Applied

Scientific EffectPhase separation:

Implementation Method 2

a surface layer that is formed on the outer periphery of the electro-conductive mandrel and that includes an electro-conductive foam

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

the electro-conductive foam includes a vulcanized product of an unvulcanized rubber composition including an acrylonitrile-butadiene rubber and a hydrin rubber

Methodology Applied

Scientific EffectVulcanization: Chemical Bonding

Data Source

PatentUS10558149B2Roller for electrphotography and production method thereof, and electrophotographic image forming apparatus

Publication Date: 2020.02.11 CANON KK

AI summary

A roller for electrophotography that has a low electric resistance value and that is still further reduced in contaminating property of other member is provided. The roller includes an electro-conductive mandrel and a surface layer having an electro-conductive foam. The electro-conductive foam includes a vulcanized product of an unvulcanized rubber composition including an acrylonitrile-butadiene rubber and a hydrin rubber. The vulcanized product has a matrix-domain structure having a sea phase and an island phase, contains ethylene oxide of 8.0% by mass or more and 20.0% by mass or less based on a total amount of the vulcanized product, and has a spin-spin relaxation time T2 of 750 μs<T2<930 μs.