Toner Silica Additive Circularity Control
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Solution Overview
Problem
Existing electrostatic charge image developing toners face issues with image density unevenness, particularly in high temperature and high humidity environments, where low image density images are continuously formed followed by high image density secondary color images, leading to transfer unevenness and aggregation of toner particles.
Innovation Solution
The development of an electrostatic charge image developing toner with a binder resin and an external additive of silica particles having a circularity of 0.5 to 0.9 and a volume average particle diameter of 100 nm to 300 nm, which prevents embedment and rolling on the toner surface, maintaining a stable two-layer structure and reducing adhesive force variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional toners are used in high temperature and high humidity environments, then toner particles aggregate and transfer unevenly, but image density uniformity deteriorates when low image density images are continuously formed followed by high image density secondary color images
Solution Approach 1:
The patent applies parameter changes by carefully controlling the circularity of silica particles within 0.5 to 0.9 and volume average particle diameter within 100 nm to 300 nm. These specific parameter ranges prevent excessive embedment and rolling of external additives, maintaining stable two-layer structure and reducing adhesive force variations that cause toner aggregation and transfer unevenness in high temperature and high humidity environments
Solution Approach 2:
The patent uses composite materials by combining binder resin with specifically shaped silica particles as external additives. The composite structure of irregularly shaped silica particles (circularity 0.5-0.9) on the toner surface creates a stable two-layer structure that prevents toner particle aggregation and maintains consistent adhesive force, thereby ensuring uniform image density transfer even under continuous low image density image formation followed by high image density secondary color image formation
2Stability of the object's composition
If silica particles with circularity of 0.5 or less or more than 0.9 are used, then external additive embedment or rolling occurs on the toner surface, but the two-layer structure stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the circularity parameter of silica particles within the range of 0.5 to 0.9. This specific parameter range is critical: particles with circularity ≤0.5 tend to embed excessively into the toner surface, while particles with circularity >0.9 tend to roll on the surface. By maintaining circularity within 0.5-0.9, the patent achieves optimal balance that prevents both embedment and rolling, ensuring stable external additive positioning and stable two-layer structure
Solution Approach 2:
The patent applies local quality by ensuring uniform distribution of silica particles with specific circularity characteristics across the toner surface. The local arrangement of particles with controlled circularity (0.5-0.9) creates consistent interaction with the binder resin, preventing localized embedment or rolling phenomena and maintaining uniform two-layer structure stability throughout the toner particle
3Reliability
If silica particles with volume average particle diameter of 100 nm or less or more than 300 nm are used, then adhesive force variations increase, but image quality consistency deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the volume average particle diameter of silica particles within the specific range of 100 nm to 300 nm. This parameter control is essential: particles ≤100 nm exhibit excessive embedment and high adhesive force variation, while particles >300 nm show insufficient surface coverage and rolling tendency. By maintaining particle diameter within 100-300 nm, the patent achieves optimal adhesive force consistency, ensuring uniform image quality across different environmental conditions and image types
Data Source
AI summary
An electrostatic charge image developing toner includes: a toner particle containing a binder resin; and an external additive including a silica particle having a circularity of more than 0.5 and 0.9 or less and a volume average particle diameter of more than 100 nm and 300 nm or less, in which a total Net intensity NA of an alkali metal element and an alkaline earth metal element in the toner particle measured by fluorescence X-ray analysis is 0.10 kcps or more and 1.20 kcps or less.