PFA Surface Layer Crystallization Control for Fixing Member Wear

Solution Overview

Problem

The existing electrophotographic fixing members with surface layers made of tetrafluoroethylene-perfluoro alkyl vinyl ether copolymer (PFA) suffer from reduced image gloss due to surface unevenness caused by large spherulite formation during gradual cooling, which compromises wear resistance and image quality.

Innovation Solution

An electrophotographic member with a surface layer comprising PFA, where a specific thermal treatment process involving differential scanning calorimetry (DSC) steps is used to control crystallization, ensuring two endothermic peaks with T1 > T2, enhancing wear resistance while maintaining high surface smoothness and image gloss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gradual cooling is performed to increase the degree of crystallinity of PFA, then wear resistance is improved, but large spherulites form causing surface unevenness and reduced image gloss

Engineering Contradiction:

Improvewear resistanceVSAvoidsurface smoothness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the cooling rate parameter from gradual cooling to rapid cooling. This parameter change prevents large spherulite formation by reducing the time for crystal growth, thereby maintaining surface smoothness and image gloss while still achieving adequate wear resistance through controlled crystallization.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies a release agent to the surface layer before the crystallization process. This beforehand cushioning prevents toner adhesion to the surface during and after crystallization, ensuring that surface smoothness and image gloss are maintained even as crystallinity increases to improve wear resistance.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Stability of the object's composition

If the surface layer is heated to a temperature equal to or higher than the melting point of PFA followed by gradual cooling, then the degree of crystallinity increases, but surface unevenness increases reducing image gloss value

Engineering Contradiction:

Improvedegree of crystallinityVSAvoidimage gloss value

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent changes the cooling rate parameter from gradual cooling to rapid cooling. This parameter change prevents large spherulite formation by reducing the time for crystal growth, thereby maintaining surface smoothness and image gloss while still achieving adequate wear resistance through controlled crystallization.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies a release agent to the surface layer before the crystallization process. This beforehand cushioning prevents toner adhesion to the surface during and after crystallization, ensuring that surface smoothness and image gloss are maintained even as crystallinity increases to improve wear resistance.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 controlled crystallization process improves wear resistance and maintains high image gloss by preventing large spherulite growth, thus extending the life of the fixing member and enhancing image quality.

Implementation Method 1

heating to a temperature equal to or higher than the melting point of the PFA

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

performing heating to a temperature equal to or higher than the melting point of the PFA, followed by gradual cooling, thereby increasing the degree of crystallinity of the PFA

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

The elastic layer functions as a layer for imparting the flexibility to the fixing member

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP4492151A1Electrophotographic member, fixing apparatus and electrophotographic image forming apparatus

Publication Date: 2025.01.15 CANON KK

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AI summary

An electrophotographic member has a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer. The surface layer includes a fluorocarbon resin. With a DSC measurement using a sample sampled from the surface layer, temperature raising and temperature lowering are performed twice at 25 to 400°C, resulting in a first DSC chart at the first temperature raising, and a second DSC chart at the second temperature raising. The first DSC chart has at least two endothermic peaks and T1°C represents the peak top temperature of the peak on the highest temperature side of them. The second DSC chart has at least one endothermic peak and T2°C represents the peak top temperature of the largest endothermic peak of them. The T1 and the T2 satisfy the following formula (1): T1>T2