Toner Surface Polyester Resin Silica Additives
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Solution Overview
Problem
Conventional toners used in electrostatic image development face issues with charge stability in varying environmental conditions, leading to fogging, image density fluctuations, and development ghosts, especially in high-temperature and high-humidity environments, and poor flowability in low-temperature and low-humidity environments, affecting image quality and longevity.
Innovation Solution
A toner with a polyester resin surface and spherical silica particles of specific size (20 nm to 40 nm) as external additives, where the polyvalent metal element's electrical resistivity and amount are optimized to maintain charge stability and prevent charge-up, ensuring consistent performance in high-speed and long-life image forming processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional toners with polyvalent metal ions are used in high-temperature and high-humidity environments, then charge amount decreases due to moisture absorption, but adding external additives increases device complexity
Solution Approach 1:
Silica particles with 20 nm to 40 nm particle diameter act as intermediary substances between the toner particle and moisture environment. These particles form a barrier layer that mediates the interaction between moisture and polyvalent metal ions, preventing moisture from reaching the metal ions and causing charge instability, thereby resolving the contradiction between maintaining charge stability and avoiding complex structures.
Solution Approach 2:
The invention optimizes specific parameters including silica particle diameter (20-40 nm), silica content (0.01-5 parts by mass per 100 parts by mass of toner particle), and polyvalent metal ion concentration. By precisely controlling these parameters, the toner achieves moisture resistance without requiring complex structural modifications, thus improving reliability while minimizing device complexity.
2Reliability
If silica particles with larger particle diameter are used as spacer particles, then external additive embedding is suppressed, but coverage effect of external additive fine particles is reduced
Solution Approach 1:
The invention identifies and optimizes the critical parameter of silica particle diameter, setting it within the specific range of 20 nm to 40 nm. This parameter optimization achieves the dual benefit of preventing external additive embedding (maintaining stability) while preserving sufficient surface coverage (maintaining quantity effect). The precise control of this size parameter resolves the contradiction between stability and coverage.
3Ease of operation
If toner is used in low-temperature and low-humidity environments for extended periods, then charge amount accumulates causing charge-up, but reducing silica content improves flowability
Solution Approach 1:
The invention optimizes the silica content parameter within the range of 0.01-5 parts by mass per 100 parts by mass of toner particle. This optimized content level provides sufficient charge dissipation capability to prevent charge-up in low-temperature environments while maintaining adequate flowability. The balanced parameter setting resolves the contradiction between ease of operation and reliability.
4Reliability
If conventional toners are used for high-speed and long-life image forming, then fogging and image density decrease occur due to charge amount reduction, but increasing polyvalent metal content improves charge stability
Solution Approach 1:
Silica particles serve as a protective intermediary that blocks moisture from reaching polyvalent metal ions. This intermediary action prevents the moisture-induced charge instability that would otherwise lead to fogging and image density decrease during high-speed and long-life operation. The silica barrier maintains charge stability without requiring increased metal content, thus eliminating the harmful effects.
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 enhanced stability in charge density, suppresses fogging, and prevents development ghosts across different environmental conditions, maintaining image quality and performance in high-speed and long-life usage scenarios.
Implementation Method 1
in a high-temperature and high-humidity environment, the charge amount of the toner tends to decrease due to the effect of moisture absorption characteristics of the polyvalent metal ions
Implementation Method 2
a part of the aluminum and the polar part, such as carboxylic acid, in a binder resin molecule forms a crosslinked structure, thereby making it possible to achieve both a satisfactory charge quantity and a low-temperature fixability
Implementation Method 3
the adhesive force of the external additive having a relatively large particle diameter to the toner particle is increased, both the spacer effect and the suppression of separation can be achieved
Data Source
AI summary
A toner comprising: a toner particle that includes a binder resin, and an external additive, wherein the toner particle includes a polyester resin on the surface; the toner particle includes a polyvalent metal element; where an electrical resistivity of the polyvalent metal element at 20° C. is denoted by A Ω·m, and an amount of the polyvalent metal element in the toner particle is denoted by B μmol/g, a following relationship is satisfied:0.025×108≤(1/A)×B≤4.500×108;the external additive includes silica particles; and the silica particles includes spherical silica particles having a number average particle diameter of from 20 nm to 40 nm.