Capsule Magnetic Toner for Low-Temperature Fixing and Offset Resistance
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Solution Overview
Problem
Existing toner technologies face challenges in achieving high-quality images with magnetic toners, particularly in terms of low-temperature fixability, offset resistance, and charging performance, due to issues with dispersion of magnetic substances and surface properties.
Innovation Solution
A magnetic toner with a capsule type structure, featuring a surface layer of polyester, vinyl, or urethane resin over a binder resin, optimized for low-viscosity and heat-resistant properties, which improves dispersibility and reduces exposure of magnetic substances, enhancing charging and transfer performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a capsule toner with high storage elastic modulus ratio (G′(60)/G′(80) ≥ 10) is used, then low-temperature fixability is improved, but sharp melt property deteriorates in high-speed devices
Solution Approach 1:
The patent modifies the chemical composition parameters of the binder resin by incorporating specific functional groups (carboxyl, hydroxyl, or amine groups) and controlling the molecular weight distribution. This changes the thermal and rheological properties of the resin, enabling it to achieve both low-temperature fixability and adequate sharp melt property for high-speed operation.
Solution Approach 2:
The patent creates a composite binder resin system combining polyester resin with specific additives and modifiers that have complementary properties. The composite structure allows the resin to exhibit both the low-temperature melting characteristics needed for energy-saving fixing and the sharp melt property required for high-speed device reliability.
2Measurement precision
If magnetic substance is dispersed in toner for high image quality, then charging performance is improved, but offset resistance deteriorates due to magnetic substance exposure
Solution Approach 1:
The patent applies local quality by creating a surface layer with different composition and properties from the core toner particles. The surface layer has optimized magnetic substance content and resin composition that provides offset resistance, while the interior maintains high magnetic substance dispersion for charging performance. This spatial differentiation of properties resolves the contradiction.
Solution Approach 2:
The patent introduces a surface-modifying resin layer as an intermediary between the magnetic substance and the external environment. This intermediate layer reduces the direct exposure of magnetic substances on the particle surface, thereby improving offset resistance while maintaining the charging performance provided by the dispersed magnetic substances in the toner core.
3Productivity
If spherical toner particles with small diameter are produced by wet method, then transfer efficiency is improved, but low-temperature fixability deteriorates when using non-polyester resins
Solution Approach 1:
The patent changes the chemical composition parameters of the binder resin to include polyester resin with specific functional groups and molecular weight characteristics. This parameter modification enables the resin to maintain low melting point and good low-temperature fixability while being compatible with the spherical particle morphology produced by wet methods, thus resolving the contradiction between transfer efficiency and fixability.
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 toner achieves excellent low-temperature fixability, offset resistance, and charging performance, reducing defects like scattering and fogging, while maintaining high image quality and stability.
Implementation Method 1
fixes the transferred image under heat and pressure
Implementation Method 2
a magnetic toner having high offset resistance and excellent charging performance
Data Source
AI summary
Provided is magnetic toner including capsule type toner particles each having a surface layer (B) on a surface of a toner base particle (A) containing at least a binder resin (a) mainly formed of a polyester, a magnetic substance, and a wax, in which, the surface layer (B) includes a resin (b), and the resin (b) includes a resin selected from the group consisting of a polyester resin (b1), a vinyl resin (b2), and a urethane resin (b3); a glass transition temperature Tg(a) of the binder resin (a) and a glass transition temperature Tg(b) of the resin (b) satisfy a relationship of Tg(a)<Tg(b); a magnetization (&sgr;t) in an external magnetic field of 79.6 kA/m of the magnetic toner is 12 Am2/kg or more and 30 Am2/kg or less; and an average circularity of the toner is 0.960 or more and 1.000 or less.