Cleaning Blade Elastic Modulus Control for Toner Fusion Prevention
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Solution Overview
Problem
Existing toner formulations for electrophotographic applications face challenges in maintaining stable cleaning performance and preventing starting streaks, especially in high-temperature, high-humidity environments, where toner fusion to the electrophotographic photosensitive member leads to image defects.
Innovation Solution
A toner formulation with a polyurethane-containing cleaning blade and a specific toner particle design, where the cleaning blade has a controlled elastic modulus and Martens hardness distribution, and the toner includes an external additive with a controlled coverage ratio and particle size, ensuring uniform force application and preventing toner fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cleaning blade with polyurethane material containing hard segment aggregates is used to achieve stable cleaning performance, then cleaning performance is improved, but starting streaks occur due to toner fusion to the photosensitive member in high-temperature environments
Solution Approach 1:
The patent applies parameter changes by precisely controlling the elastic modulus distribution (15-470 MPa average) and Martens hardness difference (≤0.30 N/mm²) of the cleaning blade. These parameter optimizations enable the blade to maintain stable cleaning performance while preventing toner fusion to the photosensitive member in high-temperature environments, thereby eliminating starting streaks without sacrificing cleaning effectiveness.
2Strength
If toner formulation is optimized for high durability and resistance to shear, then toner stability is improved, but flowability declines in the latter half of durability testing
Solution Approach 1:
The patent resolves this contradiction through parameter changes in the toner composition, specifically optimizing the binder resin content (5-20 mass%) and using a multi-component resin system including polyester resin, styrene-acrylic copolymer resin, and polyamide resin. This balanced formulation provides both high shear resistance for durability and adequate flowability for operational performance throughout the testing period.
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 provides stable cleaning performance and suppresses the occurrence of starting streaks during durability testing in high-temperature, high-humidity conditions by ensuring uniform force distribution and preventing toner fusion to the electrophotographic photosensitive member.
Implementation Method 1
a cleaning blade, wherein the cleaning blade comprises a polyurethane-containing elastic member
Implementation Method 2
the aggregates are pressed against the electrophotographic photosensitive member by the pressure of the contact portion of the cleaning blade against the electrophotographic photosensitive member
Implementation Method 3
the elastic member has a plate shape at least at the tip side, the plate shape having a main surface and a tip surface that forms a tip side edge in combination with the main surface
Data Source
AI summary
The electrophotographic apparatus and process cartridge comprising an electrophotographic photosensitive member, a cleaning blade, and developing unit containing a toner, wherein the cleaning blade comprising a support member and an elastic member whose portion is abutting a surface of the electrophotographic photosensitive member; the elastic member has an elastic modulus of 15 to 470 MPa with coefficient of variation for the elastic modulus being not more than 7.0%, and the absolute value of a difference between Martens hardness values is not more than 0.30 N/mm2 as measured under prescribed conditions; the toner contains a toner particle and an external additive whose a number-average primary particle diameter is from 5 to 25 nm, when X1 is a coverage ratio of the toner particle by the external additive and X2 is a theoretical coverage ratio, X1 is 50 to 85 area %, and X1/X2≥−0.0042×X1+0.60 is satisfied.