Magnetic Toner Yield Value Control for Fixing Stability
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Solution Overview
Problem
Magnetic toners face challenges in maintaining image stability and durability under high temperature/high humidity environments, leading to impaired image quality and reduced dot reproducibility due to toner deterioration, which existing technologies have not adequately addressed.
Innovation Solution
A magnetic toner formulation containing an inorganic fine powder, a magnetic toner particle with a binder resin and a release agent, exhibiting specific yield values in stress relaxation measurements to enhance environmental stability and balance low-temperature fixability with dot reproducibility and developing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the hardness of the toner is increased to raise heat resistance, then the heat resistance is improved, but the fixing performance deteriorates and it becomes difficult to balance developing performance and fixing performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight distribution of the binder resin. Specifically, it sets the weight-average molecular weight Mw to 5,000-50,000 and the number-average molecular weight Mn to 1,000-3,000, achieving a controlled Mn/Mw ratio. This parameter optimization allows the toner to achieve both high heat resistance and excellent fixing performance, resolving the contradiction between hardness and fixing ability.
Solution Approach 2:
The patent uses composite materials by combining binder resin with specific molecular weight distribution characteristics with magnetic bodies and other toner components. The binder resin composition, characterized by controlled Mn and Mw values, creates a composite structure that provides both the hardness needed for heat resistance and the flexibility required for proper fixing performance.
2Duration of action of stationary object
If the toner stands for a long time under severe conditions, then storage duration is extended, but toner properties deteriorate leading to impaired image quality and durability
Solution Approach 1:
The patent applies preliminary action by pre-optimizing the molecular weight distribution of the binder resin before storage. By controlling Mn to 1,000-3,000 and Mw to 5,000-50,000 during manufacturing, the toner is prepared in advance to resist deterioration. This preliminary structural optimization ensures that even after long-term storage under severe conditions, the toner maintains its charging properties, flowability, and image quality without significant degradation.
3Temperature
If low-temperature fixability is improved, then fixing at lower temperatures is achieved, but dot reproducibility and developing performance may be compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the molecular weight parameters of the binder resin. The controlled Mn (1,000-3,000) and Mw (5,000-50,000) values create a specific viscoelastic profile that enables the toner to soften adequately at lower fixing temperatures while maintaining the structural integrity needed for precise dot reproduction and consistent developing 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 toner achieves improved low-temperature fixability and dot reproducibility, maintaining performance and stability even after standing in severe environments by controlling yield values and optimizing the toner structure for stress resistance and softening during fixing.
Implementation Method 1
In a stress relaxation measurement using a rotating plate rheometer, the magnetic toner has a yield value A at 25° C. of at least 3×10^6 (sec) and the magnetic toner which has been heated to 80° C. and then cooled to 25° C. has a yield value B at 25° C. of not more than 1×10^5 (sec)
Implementation Method 2
the magnetic toner has a yield value A at 25° C. of at least 3×10^6 (sec) and the magnetic toner which has been heated to 80° C. and then cooled to 25° C. has a yield value B at 25° C. of not more than 1×10^5 (sec)
Implementation Method 3
The jumping method, which uses a magnetic toner and a rotating sleeve having a magnet pole disposed at its center and which uses an electric field to induce jumping between the surface of the photosensitive member and the surface of the sleeve
Implementation Method 4
the magnetic toner which has been heated to 80° C. and then cooled to 25° C. has a yield value B at 25° C. of not more than 1×10^5 (sec)
Data Source
AI summary
A magnetic toner is provided that exhibits an excellent dot reproducibility and developing performance after being allowed to stand in a high temperature and high humidity environment and an excellent low-temperature fixability. The magnetic toner has an inorganic fine powder and a magnetic toner particle containing a binder resin, a magnetic body, and a release agent, wherein in a stress relaxation measurement using a rotating plate rheometer, the magnetic toner exhibits a yield value A at 25° C. of at least 3×106 (sec), and the magnetic toner that has been heated to 80° C. and then cooled to 25° C. exhibits a yield value B at 25° C. of not more than 1×105 (sec).