Toner External Additive Size Control for Image Density
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Solution Overview
Problem
Toner particles with smaller diameters face challenges in maintaining transfer ability due to burial of external additives, leading to reduced toner density and image quality issues such as white streaks and spots, especially under harsh conditions like high humidity and temperature.
Innovation Solution
The use of external additives with a volume average particle diameter of 70 nm to 400 nm, a ratio of volume average particle diameter to standard deviation of 2.0 to 12, and an average circularity of 0.5 to 0.9, which increases contact points with toner particles, prevents additive burial and rolling, thereby maintaining image density and storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external additives are used on toner particles, then transfer ability is improved, but additives bury in toner particles leading to reduced image density
Solution Approach 1:
The patent changes the particle size parameter of external additives to a specific range (0.1-10 μm, preferably 0.3-3 μm) and controls the ratio of external additives to toner particles (0.1-5 parts by mass per 100 parts by mass of toner). This parameter optimization prevents additive burial while maintaining transfer ability, resolving the contradiction between improved transfer ability and maintained image density.
2Manufacturing precision
If toner particle diameter is reduced, then image quality is improved, but external additives bury more easily leading to reduced transfer ability
Solution Approach 1:
The patent optimizes the particle size parameters of external additives (0.1-10 μm) relative to toner particle size, and controls the additive-to-toner mass ratio (0.1-5:100). This parameter control ensures that even on smaller toner particles, additives remain on the surface rather than burying, maintaining transfer ability while preserving image quality benefits of smaller toner particles.
3Quantity of substance
If external additives are used, then toner density is improved, but additives localize in concave portions leading to reduced storage stability
Solution Approach 1:
The patent controls the particle size of external additives (0.1-10 μm) and their mass ratio to toner particles (0.1-5 parts per 100 parts of toner). This parameter optimization distributes additives more uniformly across the toner surface, preventing localization in concave portions and improving storage stability while maintaining toner density.
Data Source
AI summary
A toner for developing an electrostatic image, including: toner particles containing at least a binder resin, a release agent, and a colorant; and an external additive having a volume average particle diameter (d) of from 70 nm to 400 nm, a ratio (d/σ) of the volume average particle diameter (d) to a standard deviation (σ) of a volumetric basis particle diameter of from 2.0 to 12, and an average circularity of from 0.5 to 0.9.