Magnetic Carrier Coating with Doped Tin Oxide for Offset Prevention
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Solution Overview
Problem
In full-color electrophotographic image formations, the offset phenomenon and toner filming issues hinder the durability and efficiency of electrostatic latent image developing carriers, leading to poor image quality and increased maintenance costs due to high viscoelasticity of toners and inadequate surface energy coatings.
Innovation Solution
A carrier is developed by applying a resin containing phosphorus-doped tin oxide or tungsten-doped tin oxide electroconductive particles to magnetic core particles, forming a crosslinked coating layer with silane-based components, which enhances charge stability, reduces toner adhesion, and prevents coating layer scraping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a releasing agent is incorporated into a toner to prevent offset phenomenon, then the offset phenomenon is suppressed, but the toner adhesion increases and transferability to recording medium is degraded
Solution Approach 1:
The patent uses a fluoro-resin coating layer as an intermediary between the toner and the carrier surface. This coating layer has low surface energy that prevents toner adhesion to the carrier while not requiring the incorporation of releasing agents into the toner itself, thus maintaining toner transferability to the recording medium.
Solution Approach 2:
The patent changes the surface energy parameter of the carrier by coating it with a fluoro-resin layer. This coating reduces the surface energy of the carrier to a level that prevents toner adhesion during the developing process, thereby preventing offset without affecting toner transferability.
2Productivity
If the surface of a heat-fixing member is made smooth for high-thermal efficiency and glossiness, then fixing speed and image quality are improved, but the offset phenomenon occurs due to contact with molten toner
Solution Approach 1:
The fluoro-resin coating layer on the carrier acts as an intermediary that prevents direct adhesion between toner and the developing components. This indirect protection helps prevent offset phenomenon during the overall image formation process, complementing the heat-fixing process.
3Reliability
If a resin coating layer is applied to the carrier surface to prevent toner filming, then carrier durability is improved, but the coating layer may be scraped off under high-speed image forming conditions
Solution Approach 1:
The patent uses a composite coating layer made of fluoro-resin and silicone resin on the carrier surface. This composite material combines the low surface energy properties of fluoro-resin for preventing toner adhesion with the flexibility and adhesion properties of silicone resin, creating a durable coating that resists scraping under high-speed image forming conditions.
Solution Approach 2:
The patent optimizes the thickness and composition parameters of the coating layer to achieve the right balance between durability and adhesion. The coating layer is designed with specific physical and chemical properties that allow it to withstand mechanical stress during high-speed operation while maintaining its protective function.
4Object-affected harmful factors
If a releasing agent is incorporated into a toner to prevent offset, then the offset phenomenon is reduced, but toner filming occurs leading to degradation in chargeability and durability
Solution Approach 1:
The fluoro-resin coating layer on the carrier serves as an intermediary that prevents toner molecules from adhering to the carrier surface. This eliminates the need for releasing agents within the toner composition, thereby preventing toner filming and maintaining carrier service life and toner chargeability.
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 results in a high-durability carrier with stable resistivity, reduced toner scattering, and improved image quality, preventing carrier adhesion and contamination, while maintaining image quality over time and reducing environmental waste.
Implementation Method 1
electroconductive particles in which white inorganic pigments are coated with phosphorus-doped tin oxide or tungsten-doped tin oxide serving as an electroconductive material
Implementation Method 2
a resin containing certain electroconductive particles... followed by subjected to a heat treatment to thereby polycondensate crosslinking components in the resin
Implementation Method 3
followed by subjected to a heat treatment to thereby polycondensate crosslinking components in the resin
Data Source
Figure 1~2
Figure 3
AI summary
There is provided a carrier including magnetic core particles; and a coating layer on a surface of each of the magnetic core particles, wherein the coating layer contains electroconductive particles; wherein the electroconductive particles are electroconductive particles in which white inorganic pigments are coated with phosphorus-doped tin or tungsten-doped tin; and wherein a dope ratio of phosphorus or tungsten to tin in the phosphorus-doped tin or tungsten-doped tin is 0.010 to 0.100.