Magnetic Toner Surface Coverage for Electrostatic Offset Resistance

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Solution Overview

Problem

Electrophotographic technologies face challenges with electrostatic offset due to nonuniform toner charging, leading to image defects and reduced development and transfer efficiency, especially in high-temperature, high-humidity environments, where existing solutions with crystalline polyester have not provided satisfactory results.

Innovation Solution

A magnetic toner with a binder resin, magnetic body, and surface-inorganic fine particles, specifically silica, titania, and alumina, optimized for coverage ratios and containing crystalline polyester, which promotes rapid coalescence and reduces electrostatic offset by controlling the state of external addition and enhancing thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the apparatus is sped up to increase productivity, then productivity increases, but uniform charging of the toner is impaired leading to electrostatic offset

Engineering Contradiction:

Improveapparatus speedVSAvoidcharge uniformity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the toner by incorporating specific inorganic fine particles (silica, titania, alumina) in controlled amounts to modify charging characteristics and maintain charge uniformity at high speeds

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite material structure by combining organic binder resin with inorganic fine particles to create a toner composition that maintains both charging uniformity and electrostatic offset resistance

Inventive Principle:

Principle #40Composite materials

2Reliability

If crystalline polyester is added to promote rapid melting and coalescence, then electrostatic offset resistance improves, but charging performance and environmental stability deteriorate

Engineering Contradiction:

Improveelectrostatic offset resistanceVSAvoidcharging performance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention creates a composite material system combining crystalline polyester with specific inorganic fine particles to achieve both rapid coalescence and maintained charging performance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention applies local quality by having inorganic fine particles distributed throughout the toner composition to provide localized charging enhancement while crystalline polyester provides localized rapid melting capability

Inventive Principle:

Principle #3Local quality

3Reliability

If the amount of crystalline polyester is increased to improve coalescence, then electrostatic offset resistance improves, but charging performance deteriorates

Engineering Contradiction:

Improvecoalescence capabilityVSAvoidcharging performance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention optimizes the parameter balance by limiting crystalline polyester to 1-20 mass% while adding inorganic fine particles to achieve both rapid coalescence and maintained charging performance

Inventive Principle:

Principle #35Parameter changes

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 magnetic toner exhibits excellent electrostatic offset resistance both initially and during long-term use, maintaining image quality and efficiency by optimizing surface coverage and crystalline polyester outmigration.

Implementation Method 1

enhancing thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

crystalline polyester that rapidly melts in response to heating of the toner

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

magnetic toner particles comprising a binder resin and a magnetic body

Methodology Applied

Scientific EffectMagnetism: Magnetism

Data Source

PatentUS9097997B2Magnetic toner

Publication Date: 2015.08.04 CANON KK

AI summary

A magnetic toner is provided that exhibits an excellent electrostatic offset resistance both initially and after long-term use. The magnetic toner contains: magnetic toner particles containing a binder resin and a magnetic body; and inorganic fine particles present on the surface of the magnetic toner particles, wherein the inorganic fine particles present on the surface of the magnetic toner particles contain a prescribed metal oxide fine particle in a prescribed proportion; the magnetic toner has prescribed numerical value ranges for a coverage ratio A of the magnetic toner particle surface covered by the inorganic fine particles and for a coverage ratio B by the inorganic fine particles that are fixed to the magnetic toner particle surface; the magnetic toner particle contains a crystalline polyester; and measurement of the magnetic toner with a differential scanning calorimeter provides a characteristic differential scanning calorimetric curve.