Magnetic Toner Surface Coverage for Low-Temperature Fixing
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Solution Overview
Problem
Current magnetic toners face challenges in achieving both low-temperature fixability and storage stability, as improving low-temperature fixability often compromises storage stability, and existing solutions fail to effectively balance these requirements.
Innovation Solution
A magnetic toner with a specific composition including metal oxide fine particles, such as silica, titania, and alumina, and a binder resin with a styrene resin, where the coverage ratio of inorganic fine particles on the toner surface is controlled between 45.0% and 70.0%, and the release agent contains monoester or diester compounds, optimizing the softening temperature and softening point for efficient low-temperature fixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a toner composition that softens at lower temperatures is used to improve low-temperature fixability, then fixing performance at low temperature is improved, but the toner undergoes blocking in high-temperature environment and storage stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight distribution of the binder resin, specifically setting the weight-average molecular weight between 50,000-200,000 and the polydispersity index between 1.05-1.30. This optimization creates a toner that softens at lower temperatures (Ts ≤ 150°C) for improved low-temperature fixability while maintaining storage stability by preventing blocking through controlled molecular weight parameters.
Solution Approach 2:
The patent uses composite materials by combining specific types of binder resins (styrene-based resins with controlled molecular weight) and inorganic fine particles (silica, titania, alumina) in defined ratios. The inorganic fine particles are incorporated at 1-10 mass% to enhance low-temperature fixability while the composite structure prevents blocking in high-temperature environments, achieving both improved fixing performance and storage stability.
2Reliability
If external additives are used to inhibit blocking and improve storage stability, then storage stability is improved, but fixing performance is impeded because thermal conduction to the toner particle is interfered with
Solution Approach 1:
The patent applies parameter changes by optimizing the surface properties of inorganic fine particles through surface treatment (silane coupling agents or titration with aqueous solutions). This treatment modifies the particle surface to reduce interference with thermal conduction while maintaining blocking resistance, allowing the toner to achieve both storage stability and effective heat transfer during fixing.
Solution Approach 2:
The patent applies local quality by creating different surface characteristics on the toner particles - the inorganic fine particles are selectively surface-treated to provide localized regions that prevent blocking while allowing thermal conduction. The surface treatment creates a gradient in properties where the particle core maintains stability and the surface enables heat transfer, resolving the contradiction between storage stability and fixing performance.
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 excellent fixing performance at low temperatures with stable image density and improved storage stability, even in high-temperature environments, by controlling the coverage ratio and composition of the toner particles.
Implementation Method 1
external additives impede fixing because they interfere with thermal conduction to the toner particle
Implementation Method 2
the softening temperature of the magnetic toner is not more than 150° C. and the softening point of the magnetic toner is not more than 150° C.
Data Source
AI summary
A magnetic toner including: magnetic toner particles containing a binder resin, a magnetic body, and a release agent; and inorganic fine particles 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, wherein the magnetic toner has a coverage ratio A of the magnetic toner particles' surface by the inorganic fine particles and a coverage ratio B of the magnetic toner particles' surface by the inorganic fine particles fixed to the magnetic toner particles' surface that reside in prescribed numerical value ranges; the binder resin contains a styrene resin; the release agent contains a monoester compound or a diester compound; and the softening temperature and softening point of the magnetic toner reside in prescribed temperature ranges.