Toner Particle Shape Control for High-Speed Image Stability
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Solution Overview
Problem
Existing toners face challenges in maintaining image reproducibility and density uniformity, especially at high speeds and in high-temperature, high-humidity environments, due to issues with fluidity and electrostatic charge, leading to potential toner scattering and staining within the apparatus.
Innovation Solution
A toner formulation comprising a binder resin, colorant, and releasing agent with specific particle diameter and circularity degree distributions, utilizing a crystalline polyester resin with an aliphatic dicarboxylic acid and aliphatic diol-derived components, optimized through an emulsification and aggregation method to enhance fluidity and prevent scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional toner formulations are used, then image formation can proceed, but tone reproducibility and density uniformity deteriorate at high speeds and in high-temperature, high-humidity environments
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle diameter distribution and circularity degree distribution of toner particles. Specifically, it regulates the content ratio of particles with diameter 4.5-7.5 μm and circularity ≥0.980 to 5-15 number%, and particles with diameter 7.5-15 μm and circularity 0.900-0.940 to 5 number% or less. This parameter optimization ensures stable image quality across varying environmental conditions and high-speed operation.
Solution Approach 2:
The patent uses a composite binder resin system comprising a crystalline polyester resin and a non-crystalline polyester resin in specific weight ratios (crystalline: 10-40 parts, non-crystalline: 60-90 parts). This composite material structure combines the advantages of both resin types to maintain toner fluidity and electrostatic charge stability under high-temperature and high-humidity conditions.
2Object-generated harmful factors
If toner fluidity is increased to prevent scattering, then toner scattering is reduced, but density uniformity and image quality may deteriorate
Solution Approach 1:
The patent optimizes particle diameter and circularity parameters to balance fluidity and density uniformity. By controlling the content ratio of highly circular particles (4.5-7.5 μm, circularity ≥0.980) to 5-15 number% and limiting irregular particles (7.5-15 μm, circularity 0.900-0.940) to 5 number% or less, the toner achieves sufficient fluidity to prevent scattering while maintaining uniform density distribution for high-quality image formation.
Solution Approach 2:
The composite binder resin system (crystalline polyester resin + non-crystalline polyester resin) provides optimized fluidity characteristics. The crystalline resin contributes to structural stability and melting behavior, while the non-crystalline resin enhances fluidity, together preventing toner scattering without compromising density uniformity.
3Productivity
If high-speed image formation is performed, then productivity increases, but tone reproducibility and density uniformity deteriorate due to toner scattering and staining
Solution Approach 1:
The patent optimizes toner particle parameters (diameter 4.5-15 μm with specific circularity distributions) to ensure stable flow characteristics at high speeds. The controlled particle size and shape distribution prevent toner scattering during rapid image formation, enabling high productivity while maintaining excellent tone reproducibility and density uniformity.
Solution Approach 2:
The composite binder resin system provides the necessary fluidity and electrostatic charge stability for high-speed operation. The combination of crystalline and non-crystalline polyester resins ensures the toner maintains proper flow properties and charge characteristics even under high-speed image formation conditions, preventing staining and maintaining image quality.
4Temperature
If crystalline polyester resin content is increased to improve low-temperature fixability, then fixing performance improves, but toner fluidity and electrostatic charge stability deteriorate in high-temperature, high-humidity environments
Solution Approach 1:
The patent employs a composite binder resin system where crystalline polyester resin (10-40 parts by weight) provides low-temperature fixability, while non-crystalline polyester resin (60-90 parts by weight) maintains toner fluidity and electrostatic charge stability. This balanced composition prevents toner scattering in high-temperature, high-humidity environments while achieving effective fixing at lower temperatures.
Solution Approach 2:
The patent optimizes the weight ratio parameters of crystalline to non-crystalline polyester resin (10-40:60-90) to balance fixing performance and environmental stability. This parameter optimization ensures the toner maintains proper fluidity and charge characteristics in challenging environments while achieving good 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 improved tone reproducibility and density uniformity, reducing the occurrence of toner scattering and staining, even at high speeds and in challenging environmental conditions, while maintaining image quality and stability.
Implementation Method 1
a latent image is electrically formed, using various methods, on a surface of a photoreceptor (image holding member)
Implementation Method 2
the formed latent image is developed using a toner for electrostatic charge image development to form a toner image, then the toner image on the photoreceptor surface is transferred to a surface of a transfer-receiving body
Implementation Method 3
the transferred image is heated, pressurized, or heated and pressurized, to fix the image
Data Source
AI summary
There is provided a toner for developing an electrostatic charge image including a binder resin, a colorant and a releasing agent, wherein the content ratio of particles having a number particle diameter of 4.5 μm or more and less than 7.5 μm and a circularity degree of 0.980 or more is in a range from about 5 number % to about 15 number %, and the content ratio of particles having a number particle diameter of not 7.5 μm or more and less than 15 μm and a circularity degree of 0.900 or more and less than 0.940 is about 5 number % or less.