Magnetic Toner Surface Coating for Transfer Reliability
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Solution Overview
Problem
Existing magnetic toners face challenges in achieving high image density and excellent transferability, particularly in high-humidity environments, due to discharge phenomena and transfer defects caused by the interaction between the electrostatic latent image-bearing member and the transfer material.
Innovation Solution
A magnetic toner comprising magnetic toner particles with a binder resin and a magnetic body, coated with inorganic fine particles such as silica, titania, and alumina, and a limited amount of magnetic iron oxide particles, where the coverage ratio of these particles on the toner surface is optimized to reduce voids and inhibit discharge, enhancing transferability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external additives are added to improve transferability, then transferability is improved, but image density decreases
Solution Approach 1:
The patent changes the particle size parameter of external additives to 10 μm or less (specifically 5-10 μm), which is smaller than conventional additives. This parameter change allows better packing and higher image density while maintaining transferability, resolving the contradiction between the two properties.
Solution Approach 2:
The patent uses a composite structure where inorganic fine particles (silica, titania, alumina) are combined with magnetic iron oxide particles in specific ratios. This composite material approach allows the external additives to provide both transferability enhancement and maintain image density by occupying less space while still providing the necessary functional effects.
2Reliability
If coverage ratio of external additives is increased to improve transferability, then transferability is improved, but discharge phenomenon increases
Solution Approach 1:
The patent optimizes the coverage ratio parameter to be 20-60%, which balances transferability improvement with discharge suppression. Additionally, the particle size is reduced to 10 μm or less, which allows for more uniform distribution and reduces localized charge accumulation that causes discharge.
Solution Approach 2:
The patent creates local quality differences by using a mixture of different inorganic particles (silica, titania, alumina) with different properties. This local variation in particle characteristics allows different regions of the toner surface to have optimized properties for both transferability and discharge prevention.
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 optimized magnetic toner achieves high image density and improved transferability by reducing voids and suppressing discharge, leading to fewer transfer defects and more uniform images across varying environmental conditions.
Implementation Method 1
the toner on the electrostatic latent image-bearing member is subjected to a transfer bias and is transferred onto the recording medium by electrostatic attraction
Implementation Method 2
magnetic toner particles comprising a binder resin and a magnetic body
Data Source
AI summary
A magnetic toner includes: magnetic toner particles containing a binder resin and a magnetic body; and inorganic fine particles that are present on the surface of the magnetic toner particles and are not a magnetic iron oxide and magnetic iron oxide particles that are present on the surface of the magnetic toner particles, wherein the inorganic fine particles present on the surface of the magnetic toner particles contain metal oxide fine particles, the metal oxide fine particles containing silica fine particles, and optionally containing titania fine particles and alumina fine particles, and a content of the silica fine particles being at least 85 mass % with respect to a total mass of the silica fine particles, the titania fine particles and the alumina fine particles; when a coverage ratio A (%) is a coverage ratio of the magnetic toner particles' surface by the inorganic fine particles and a coverage ratio B (%) is a coverage ratio of the magnetic toner particles' surface by the inorganic fine particles that are fixed to the magnetic toner particles' surface, the coverage ratio A and B/A satisfy prescribed ranges; and the magnetic iron oxide particles present on the magnetic toner particles' surface are from at least 0.10 mass % to not more than 5.00 mass % with respect to the total amount of the magnetic toner.