Polyester Toner with Metal Catalyst Ionic Cross-Linking
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Solution Overview
Problem
In the context of electrophotographic image forming, toners with polyester resin binders face challenges in maintaining high image density and thin-line reproducibility over long-term use due to charge accumulation and dispersibility issues with colorants, particularly when using metal catalysts like tin compounds, which are also environmentally and safety concerns.
Innovation Solution
A toner composition incorporating colored particles with a polyester resin and external additive particles, featuring a specific ratio of titanium, germanium, or aluminum as catalyst metals, and complex oxides with silicon, titanium, and aluminum, which form an ionic cross-linking structure to stabilize charge and prevent excessive charge accumulation, ensuring high image quality and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If polyester resin is used as binder resin to obtain high glossiness and prevent offset, then image quality is improved, but charge accumulation occurs during long-term use causing decreased image density
Solution Approach 1:
The invention changes the chemical parameters of the polyester resin by controlling the equivalent weight (40-100 eq/kg) and incorporating specific metal catalysts (titanium, germanium, or aluminum) at controlled ratios (0.01-5 wt%). This parameter optimization allows the resin to maintain both glossiness and charge stability during long-term use.
Solution Approach 2:
The invention creates a composite binder resin system combining polyester resin with metal catalysts (titanium, germanium, or aluminum) and colorants. This composite structure provides synergistic effects where the metal catalysts enhance charge control while the polyester resin maintains glossiness and prevents offset.
2Ease of manufacture
If tin compounds are used as catalysts to synthesize polyester resin, then resin synthesis is improved, but environmental safety and dispersibility of colorant deteriorate
Solution Approach 1:
The invention replaces persistent organotin compounds with alternative metal catalysts (titanium, germanium, aluminum) that are more environmentally friendly. These catalysts achieve the same resin synthesis function without the environmental persistence and toxicity issues of tin compounds.
Solution Approach 2:
The invention changes the catalyst type from tin compounds to titanium/germanium/aluminum-based catalysts, altering the chemical composition parameters while maintaining catalytic effectiveness. This substitution improves environmental safety and colorant dispersibility.
3Reliability
If metal catalysts like titanium, germanium, or aluminum are incorporated to improve charge control, then image density is improved, but excessive charge accumulation occurs during long-term use
Solution Approach 1:
The invention optimizes the concentration parameters of metal catalysts to 0.01-5 wt% in the binder resin. This precise parameter control ensures sufficient charge control for high image density while preventing excessive charge accumulation during long-term use.
Solution Approach 2:
The invention uses a controlled, moderate amount of metal catalysts rather than excessive quantities. This partial action approach provides just enough charge control to maintain image density without causing harmful charge accumulation in the developing unit.
4Measurement precision
If particle diameter is decreased to achieve high image quality, then resolution is improved, but manufacturing precision and uniformity deteriorate
Solution Approach 1:
The invention controls the particle diameter parameter within the 4.5-8.0 μm range with a volume-based median diameter and narrow distribution (CV value of 15-25%). This parameter optimization enables high image resolution while maintaining manufacturing precision and particle uniformity through the aqueous medium granulation process.
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 stable high image density and thin-line reproducibility by forming an ionic cross-linking structure and inhibiting charge accumulation, maintaining image quality over extended use periods.
Implementation Method 1
such a specific catalyst metal, existing at a minute amount, is bonded to the polyester resin to form an ionic cross-linking structure, whereby so-called charge providing properties are exerted
Implementation Method 2
when the toner is used over a long term period, electrical charge is accumulated in the toner inside the developing unit, resulting in decreased developability
Data Source
AI summary
It is to provide a toner which can form an image of high image quality exhibiting high resolution wherein a final visible image exhibits high image density and high thin-line reproducibility even in long-term use. In a toner incorporating at least a colored particle containing a binder resin composed of a polyester resin and a colorant, and external additive particles, the toner has a degree of average circularity of 0.950-0.990, a volume based median diameter of 4.5-8.0 μm, a volume based particle diameter dispersibility (CVVOL value) of 15-25; a metal selected from titanium, germanium, and aluminum is incorporated at a ratio of 10-1500 ppm; the above external additive particles is composed of a composite oxide incorporating a silicon atom and at least either of a titanium atom and an aluminum atom; and the existence ratio of silicon atoms in the surface thereof is higher than the existence ratio of silicon atoms in the entire part thereof.