Spherical Silica Toner Additives for Stable Chargeability
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Solution Overview
Problem
Conventional toners experience changes in chargeability and fluidity when subjected to high stress, leading to unstable image quality and density over time, particularly due to the embedding of silica particles into toner particles.
Innovation Solution
A toner formulation with inorganic fine particles having a specific particle size distribution and shape factor, ensuring broad particle size distribution and spherical shape, which prevents embedding and maintains spacer effect, thereby stabilizing chargeability and fluidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If silica particles in an odd form are added to maintain fluidity, then fluidity is improved, but chargeability deteriorates due to reduced microscopic fluidity on toner particle surfaces
Solution Approach 1:
The invention changes the shape parameter of silica particles from odd forms to substantially spherical forms (shape factor SF-2: 104 or more and 116 or less). This parameter change maintains fluidity while preserving microscopic fluidity on toner particle surfaces, thereby maintaining chargeability. The spherical shape allows particles to roll smoothly on toner surfaces without significantly reducing microscopic fluidity.
Solution Approach 2:
The invention creates a composite toner system combining resin particle main bodies with substantially spherical silica particles as external additives. This composite structure achieves both fluidity maintenance and chargeability preservation by selecting silica particles with specific shape characteristics that complement the toner particle surfaces without disrupting microscopic fluidity.
2Ease of operation
If silica particles are added to provide spacer effect, then fluidity is maintained, but embedding occurs under mechanical load causing change in toner chargeability
Solution Approach 1:
The invention changes the shape parameter of silica particles to substantially spherical forms with shape factor SF-2 of 104 or more and 116 or less. This parameter change prevents embedding under mechanical load while maintaining the spacer effect, thereby preserving chargeability stability during image formation.
Solution Approach 2:
The invention applies spheroidality by using substantially spherical silica particles instead of odd-shaped particles. The spherical shape with high curvature resistance prevents embedding into toner particle surfaces under mechanical load, maintaining both fluidity and chargeability stability throughout the image formation process.
3Ease of operation
If odd-shaped silica particles are used, then fluidity is improved, but image density changes due to reduced microscopic fluidity
Solution Approach 1:
The invention changes the shape parameter of silica particles to substantially spherical forms (shape factor SF-2: 104 or more and 116 or less). This parameter change maintains both fluidity and microscopic fluidity on toner particle surfaces, ensuring stable image density during the image formation process.
Solution Approach 2:
The invention uses substantially spherical silica particles with high curvature to maintain microscopic fluidity on toner surfaces. This spherical geometry prevents significant reduction in microscopic fluidity, thereby maintaining stable image density while preserving fluidity benefits.
Data Source
AI summary
A toner having chargeability and fluidity that do not change to a great extent is provided. The toner includes toner particles containing a binder resin and includes inorganic fine particles A, wherein the shape factor SF-2 of primary particles of the inorganic fine particles A is 116 or less, and regarding the particle size distribution on a volume basis of the inorganic fine particles A on the toner particle surfaces, the particle diameter when a cumulative value from the small particle side reaches 16% by volume is denoted as D16, the particle diameter when a cumulative value reaches 50% by volume is denoted as D50, and the particle diameter when a cumulative value reaches 84% by volume is denoted as D84, D50 is 80 nm or more and 200 nm or less, and the particle size distribution indicator A represented by D84/D16 is 1.70 or more and 2.60 or less.