Toner External Additive Preventing Electrostatic Aggregation
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Solution Overview
Problem
Toner used in laser beam printers experiences electrostatic aggregation of small-diameter silica particles, leading to image quality decline, poor flowability, and development ghosting due to electrostatic latent image disturbance and burial of small-diameter particles by large-diameter particles during long-term use.
Innovation Solution
A toner formulation with a high-circularity, large-diameter organosilicon polymer external additive having a specific dielectric constant and shape factor, which prevents electrostatic aggregation and burial, maintaining high image quality and flowability by breaking up electrostatic aggregates and ensuring stable attachment to the toner particle surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large amounts of small-diameter silica particles are added to improve flowability and charging performance, then the toner can maintain high durability, but electrostatic aggregation occurs causing image quality decline and poor control
Solution Approach 1:
The patent introduces organosilicon polymer particles as an intermediary substance between the small-diameter silica particles and the toner particle surface. These polymer particles have specific properties (dielectric constant between 2.0-3.5, particle diameter 0.03-0.3 μm) that prevent electrostatic aggregation of the silica particles while maintaining their beneficial effects on flowability and charging performance.
Solution Approach 2:
The patent changes the physical and chemical parameters of the external additive system by specifying precise ranges for the organosilicon polymer particles including dielectric constant (2.0-3.5), particle diameter (0.03-0.3 μm), and coverage ratio (10-80%). These parameter optimizations prevent electrostatic aggregation while maintaining durability.
2Ease of operation
If small-diameter silica particles are used to improve flowability, then charging performance increases, but the particles undergo electrostatic aggregation and detachment during long-term use
Solution Approach 1:
The organosilicon polymer particles serve as a stabilizing intermediary that coats the toner particle surface and prevents electrostatic aggregation of the small-diameter silica particles. This mediator maintains the dispersed state of silica particles throughout the toner's lifetime, ensuring stable flowability and charging performance.
Solution Approach 2:
The patent creates a composite external additive system combining organosilicon polymer particles with small-diameter silica particles. This composite structure leverages the low dielectric constant and appropriate size of the polymer particles to stabilize the silica particles while maintaining the desired flowability and charging characteristics.
3Reliability
If large-diameter silica particles are used to prevent burial, then embedding-inhibiting effect is achieved, but small-diameter particles are still buried in the latter half of long-term use
Solution Approach 1:
The organosilicon polymer particles act as a protective intermediary layer that prevents both large-diameter and small-diameter silica particles from being buried into the toner particle surface. This intermediary coating maintains the functionality of small-diameter particles throughout the entire operational lifetime of the toner.
Solution Approach 2:
The patent applies organosilicon polymer particles as a preventive cushioning layer before the silica particles can be buried during long-term use. This prior protection ensures that both large and small-diameter silica particles remain accessible on the toner surface throughout the toner's operational life.
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 maintains high developing performance and image quality over a long-term lifetime without image defects, as the organosilicon polymer particles effectively prevent electrostatic aggregation and burial, ensuring consistent toner flow and charging performance.
Implementation Method 1
electrostatic aggregation of the small-diameter silica particles that are added in large amounts
Implementation Method 2
the external additive A and the external additive B are contained in specific amounts
Data Source
AI summary
A toner comprising: a toner particle containing a binder resin; and an external additive, wherein the external additive comprises an external additive A and B; the external additive A has a number-average primary particle diameter of 35 to 300 nm, a dielectric constant εra of not more than 3.50, and a shape factor SF-1 of not more than 114, and is an organosilicon polymer particle having a particular T3 unit structure; a proportion for an area of a peak originating from silicon having the T3 unit structure with reference to that of all silicon elements is 0.50 to 1.00; the external additive B has a number-average primary particle diameter of from 5 nm to 25 nm and a dielectric constant εrb that satisfies formula (A): 0.50 ≤ εrb - εra (A); and a coverage ratio by the external additive B for the toner particle surface is 50% to 100%.