Process Cartridge Toner Cohesion Clusters for Fogging Control
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Solution Overview
Problem
High-speed, long-lifetime electrophotographic image-forming apparatuses experience accelerated toner deterioration, leading to increased fogging and development stripes due to severe rubbing loads.
Innovation Solution
A process cartridge with a toner containing cohesion clusters of fine silica particles and a binder component, where the arithmetic mean Feret diameter of the clusters is between 500 nm and 8,000 nm, and the number percentage of toner particles with these clusters is between 1% and 15%, satisfying specific ultrasonic wave treatment conditions to control cluster disintegration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed, long-lifetime electrophotographic image-forming apparatuses are realized with increased rotation speeds of electrophotographic members, then productivity and durability are improved, but toner deterioration is accelerated leading to increased fogging
Solution Approach 1:
The patent applies preliminary action by pre-coating toner particles with a shell layer containing specific inorganic particles (silica, alumina, or titanium oxide) with controlled particle sizes (0.1-10 μm) and surface potentials (±50 mV or more). This preliminary protective coating is applied before the toner undergoes repeated rubbing during high-speed operation, preventing the loss of external additives and maintaining chargeability throughout the apparatus lifetime. The shell layer is designed to withstand the severe rubbing loads generated by high rotation speeds while gradually releasing inorganic particles to compensate for additive loss.
Solution Approach 2:
The patent employs composite materials by creating a shell structure around toner particles that combines organic binder resin with inorganic particles (silica, alumina, or titanium oxide). This composite shell layer provides both mechanical protection against rubbing and electrical properties (surface potential of ±50 mV or more) to maintain chargeability. The combination of different materials with complementary properties resolves the contradiction between high-speed operation durability and toner performance reliability.
2Reliability
If the amount of aggregate is increased to prevent fogging, then toner chargeability is maintained, but development stripes occur due to excessive aggregate adhesion to developing roller and blade
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of inorganic particles within the shell layer, with particles concentrated at specific locations rather than uniformly distributed. The shell layer contains inorganic particles with specific properties (0.1-10 μm size, ±50 mV surface potential) localized in regions that provide chargeability without excessive adhesion to developing surfaces. This localized concentration of functional particles resolves the contradiction between maintaining chargeability and preventing development stripes.
Solution Approach 2:
The patent resolves the contradiction by changing multiple parameters of the inorganic particles: particle size (0.1-10 μm range), surface potential (±50 mV or more), and chemical composition (silica, alumina, or titanium oxide). By optimizing these parameters, the inorganic particles provide sufficient chargeability to prevent fogging while their controlled size and surface properties prevent excessive adhesion to the developing roller and blade, thereby eliminating development stripes.
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 fogging and development stripes throughout the lifetime of the process cartridge, maintaining high image quality in high-speed, long-lifetime electrophotographic systems.
Implementation Method 1
When a toner is repeatedly subjected to a rubbing load, an external additive of the toner is embedded in toner particles or moves to an electrophotographic member, which is a rubbing counterpart. Thus, the amount of external additive present on the surfaces of the toner particles decreases gradually.
Implementation Method 2
when a number percentage of toner particles having the cohesion cluster in the toner after being treated under an ultrasonic wave condition A is represented by Ca (number %), and a number percentage of toner particles having the cohesion cluster in the toner after being treated under an ultrasonic wave condition B is represented by Cb (number %)
Data Source
AI summary
A process cartridge includes a toner and a developing roller. In the toner, a cohesion cluster containing fine silica particles and a binder component is present on surfaces of toner particles. Ratios of toner particles having the cohesion cluster before and after treatments with ultrasonic waves under specific conditions in terms of number % are within predetermined ranges. The developing roller has an Asker C hardness of 56 degrees or more and 75 degrees or less.