Fluorinated Polyester Resin Surface Layer for Photosensitive Member

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Solution Overview

Problem

Electrophotographic photosensitive members with enhanced mechanical strength using polyester resin and charge-transporting substances face degradation in high-temperature, high-humidity environments, leading to image quality issues due to chemical deterioration and increased polarity in the surface layer.

Innovation Solution

Incorporating a polyester resin with a specific repeating structural unit, such as Formula (A), and a charge-transporting substance like compounds represented by Formula (CTM-1) or enamine compounds in the surface layer, with a content of 30% or more by mass, to enhance mechanical strength while minimizing chemical deterioration and maintaining image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polyester resin and charge-transporting substances are used to enhance mechanical strength, then the surface layer gains high mechanical strength, but image quality degrades in high-temperature, high-humidity environments due to chemical deterioration

Engineering Contradiction:

Improvemechanical strength of surface layerVSAvoidimage quality stability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the polyester resin by incorporating fluorinated aromatic rings and trifluoromethyl groups. This chemical modification reduces the resin's susceptibility to chemical deterioration in high-temperature, high-humidity environments while preserving mechanical strength, thus resolving the contradiction between strength enhancement and reliability maintenance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining polyester resin with specific charge-transporting substances (compounds of formulae CTM-1, CTM-4, or enamine compounds) in a controlled mass ratio. This composite approach allows the fluorinated polyester to provide chemical stability while the charge-transporting substances maintain electrophotographic functionality, resolving the contradiction between mechanical strength and image quality stability.

Inventive Principle:

Principle #40Composite materials

2Strength

If the surface layer uses conventional polyester resin to improve mechanical strength, then abrasion resistance increases, but chemical deterioration occurs leading to increased polarity and image quality degradation

Engineering Contradiction:

Improveabrasion resistanceVSAvoidchemical deterioration and polarity increase

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the polyester resin's chemical structure by introducing fluorinated aromatic rings and trifluoromethyl groups. This parameter change in molecular structure reduces the resin's polarity and chemical reactivity, making it resistant to chemical deterioration during repeated use in harsh environments while maintaining abrasion resistance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a small amount (0.1-10 mass%) of fluorinated aromatic ring-containing dicarboxylic acid or dicarboxylic acid ester as a modifier in the polyester resin synthesis. This small additive amount provides long-lasting chemical stability to the entire surface layer, preventing chemical deterioration without requiring complete replacement of the resin system.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 image quality degradation and maintains high mechanical strength by using a polyester resin with a trifluoromethyl group, which is less susceptible to chemical modification, thereby reducing the accumulation of chemically deteriorated material and maintaining image quality during repeated use in harsh environments.

Implementation Method 1

a polyester resin having a repeating structural unit represented by the Formula (A)... capable of suppressing degradation of image quality due to repeated use of the electrophotographic photosensitive member in a high-temperature, high-humidity environment... which is less susceptible to chemical modification

Methodology Applied

Scientific EffectChemical resistance:

Implementation Method 2

at least one charge-transporting substance selected from the group consisting of a compound represented by the Formula (CTM-1), a compound represented by the Formula (CTM-4), and an enamine compound

Methodology Applied

Scientific EffectCharge transport:

Data Source

PatentUS9091912B2Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

Publication Date: 2015.07.28 CANON KK

AI summary

An electrophotographic photosensitive member includes a surface layer including a particular charge-transporting substance and a particular polyester resin having a particular repeating structural unit. The content of the particular repeating structural unit is 30% by mass or more based on the total mass of the polyester resin included in the surface layer.