Electrophotographic Member Urethane Surface Layer Compression Set

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Solution Overview

Problem

The surface layer of electrophotographic members containing urethane resin often experiences compression set due to the penetration of low-molecular weight components from the elastic layer, leading to reduced hardness and uneven toner conveyance, which affects the quality of electrophotographic images.

Innovation Solution

An electrophotographic member with a surface layer comprising a urethane resin formed from specific polyester polyols and polyisocyanates, which includes a hydroxyl group-terminated prepolymer and an isocyanate-terminated prepolymer, is used to prevent the penetration of low-molecular weight components and maintain the hardness of the surface layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a surface layer containing urethane resin is provided on the elastic layer, then toner conveyance performance is improved, but compression set occurs in the abutment portion due to penetration of low-molecular weight components from the elastic layer

Engineering Contradiction:
Improvetoner conveyance performanceVSAvoidhardness of surface layer
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

A barrier layer is introduced between the elastic layer and the surface layer containing urethane resin. This barrier layer prevents the penetration of low-molecular weight components from the elastic layer into the surface layer, thereby preventing compression set and hardening of the surface layer, while allowing the surface layer to maintain its toner conveyance performance

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrophotographic member is divided into multiple functional layers: an elastic layer, a barrier layer, and a surface layer containing urethane resin. This segmentation allows each layer to perform its specific function independently - the elastic layer provides flexibility, the barrier layer prevents component migration, and the surface layer ensures toner conveyance

Inventive Principle:
Principle #1Segmentation

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 suppresses compression set and maintains the surface layer's hardness, ensuring stable and high-quality electrophotographic images by preventing the migration of low-molecular weight components, thus enhancing the durability and performance of the electrophotographic member.

Implementation Method 1

the penetration of low-molecular weight components from the elastic layer

Methodology Applied
Scientific EffectPermeation resistance: Permeation

Data Source

PatentEP2881797B1Electrophotographic member and electrophotographic apparatus
Publication Date: 2017.06.14 CANON KK
  • EP2881797B1 patent drawingFigure 1A~1B
  • EP2881797B1 patent drawingFigure 2
  • EP2881797B1 patent drawingFigure 3~4

AI summary

Provided is an electrophotography member that resists change in performance even if left unused for lengthy periods. The electrophotography member has a base, an elastic layer formed upon the base, and a surface layer covering the surface of the elastic layer and including urethane resin. The electrophotography member is characterized by the urethane resin being a reaction product from: a hydroxyl-terminated prepolymer obtained by reacting a polyester polyol and a polyisocyanate; and a isocyanate-terminated prepolymer obtained by reacting a polyester polyol and polyisocyanate.