Electrostatic Toner Viscosity Control for Image Density Stability
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Solution Overview
Problem
Image forming apparatuses face issues with image density decrease and unevenness in high-temperature and high-humidity environments when using toners with excessively low viscoelasticity, and with unevenness in low-temperature and low-humidity environments when using toners with excessively high viscoelasticity, due to the reuse of electrostatic image developing toner collected by the cleaning unit.
Innovation Solution
The use of a specific electrostatic image developing toner that contains toner particles and an external additive, with viscosity properties satisfying certain inequalities, ensuring appropriate viscoelasticity and reducing the likelihood of external additives being buried or coming off during reuse, thereby maintaining image density and uniformity across varying environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If toner with low viscoelasticity is used, then external additives are less likely to be buried, but image density decreases in high-temperature and high-humidity environments
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscoelasticity of the toner through specific viscosity ratios at different temperatures. The invention defines that the ratio of viscosity at 60°C to viscosity at 90°C should be 0.05 to 0.5, and the ratio of viscosity at 90°C to viscosity at 130°C should be 0.5 to 2.0. This parameter optimization ensures the toner maintains appropriate stickiness across varying environmental conditions, preventing both external additive burial and image density decrease.
2Stability of the object's composition
If toner with high viscoelasticity is used, then external additives are less likely to come off, but unevenness in image density occurs in low-temperature and low-humidity environments
Solution Approach 1:
The patent resolves this contradiction by establishing specific viscosity ratio parameters. The viscosity at 60°C relative to 90°C should be 0.05 to 0.5, ensuring the toner is not too sticky in cold conditions. The viscosity at 90°C relative to 130°C should be 0.5 to 2.0, preventing excessive stickiness in warm conditions. These parameter controls maintain external additive retention while ensuring uniform image density across different environmental conditions.
3Loss of substance
If collected toner is reused, then material efficiency improves, but image quality deteriorates due to viscosity changes in different environments
Solution Approach 1:
The patent enables toner reuse while maintaining image quality by controlling the viscosity characteristics of the toner formulation. The specified viscosity ratios ensure that collected toner maintains stable flow and adhesion properties after being subjected to storage and reuse cycles, preventing image quality deterioration despite repeated use across varying environmental conditions.
Solution Approach 2:
The invention employs composite material principles by formulating the toner with specific resin and additive combinations that achieve the desired viscosity characteristics. This composite formulation ensures the toner maintains appropriate viscoelasticity for reuse while preventing the image quality issues that would otherwise occur with collected toner in different environmental conditions.
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 specific toner maintains consistent image density and reduces unevenness in both high-temperature and high-humidity, and low-temperature and low-humidity environments by controlling viscosity changes, ensuring reliable image formation.
Implementation Method 1
the electrostatic image developing toner contains toner particles and an external additive and satisfies inequalities below: (ln η(T1)−ln η(T2))/(T1-T2)≤−0.14, (ln η(T2)−ln η(T3))/(T2-T3)≥−0.15, and (ln η(T2)−ln η(T3))/(T2-T3)>(ln η(T1)−ln η(T2))/(T1-T2) wherein η(T1) represents a viscosity of the electrostatic image developing toner at 60° C., η(T2) represents a viscosity of the electrostatic image developing toner at 90° C., and η(T3) represents a viscosity of the electrostatic image developing toner at 130° C.
Data Source
AI summary
An image forming apparatus includes an image carrier; a charging unit that charges a surface of the image carrier; an electrostatic image forming unit that forms an electrostatic image on the charged surface of the image carrier; a developing unit that contains an electrostatic image developing toner and develops the electrostatic image formed on the surface of the image carrier with the electrostatic image developing toner to form a toner image; a transfer unit that transfers the toner image formed on the surface of the image carrier to a recording medium; a cleaning unit that removes the electrostatic image developing toner remaining on the surface of the image carrier; a first supply unit that has a replenishment toner transport path for transporting a replenishment toner for the electrostatic image developing toner and supplies the replenishment toner to the developing unit; a second supply unit that collects the electrostatic image developing toner removed by the cleaning unit, that has a collected toner transport path for transporting the collected toner to the developing unit, and that supplies the collected toner to the developing unit; and a fixing unit that fixes the toner image transferred to the recording medium. The electrostatic image developing toner contains toner particles and an external additive and satisfies the following inequalities: (ln η(T1)−ln η(T2))/(T1-T2)≤−0.14, (ln η(T2)−ln η(T3))/(T2-T3)≥−0.15, (ln η(T1)−ln η(T2))/(T1-T2)<(ln η(T2)−ln η(T3))/(T2-T3), wherein η(T1) represents a viscosity of the electrostatic image developing toner at 60° C., η(T2) represents a viscosity of the electrostatic image developing toner at 90° C., and η(T3) represents a viscosity of the electrostatic image developing toner at 130° C.