Two-Component Developing Agent with Dendritic Titanium Oxide Coating

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Solution Overview

Problem

Current two-component developing agents for electrophotography face challenges in maintaining high image density and stability over time, particularly in high-speed and small-sized printers, due to issues with toner scattering, fluidity, and adhering forces between toner and carrier, leading to deteriorated image quality and contamination.

Innovation Solution

A two-component developing agent comprising a toner and a carrier with a silicone resin coating layer containing dendritic titanium oxide, which provides stable frictional chargeability and fluidity, suppressing toner scattering and maintaining high image density, with specific surface area and particle size optimizations for the titanium oxide and toner.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional two-component developing agents are used in high-speed printers, then productivity is improved, but toner scattering increases and image density deteriorates

Engineering Contradiction:
Improvehigh-speed operationVSAvoidimage density
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention changes the physical and chemical parameters of the carrier by using ferrite core material with specific magnetic properties (saturation magnetization 150-300 emu/g, specific resistance 10^-4-10^-6 ohm·cm) and controlling the coating layer thickness to 0.01-5 μm. These parameter changes optimize the carrier's ability to hold and transport toner at high speeds while preventing toner scattering, thus resolving the contradiction between productivity and image density.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite structure consisting of a ferrite core material and a resin coating layer. The ferrite core provides magnetic properties for toner transport, while the resin coating layer (containing 1-50 wt% inorganic oxide) provides toner adhesion and prevents scattering. This composite material approach enables both high-speed operation and high image density by combining the advantages of different materials.

Inventive Principle:
Principle #40Composite materials

2Productivity

If the carrier coating layer is made thinner to improve toner fluidity, then productivity is improved, but carrier adhesion to the developing roller deteriorates

Engineering Contradiction:
Improvetoner fluidityVSAvoidcarrier adhesion
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention optimizes the coating layer thickness parameter to a specific range of 0.01-5 μm, which is thin enough to allow good toner fluidity but thick enough to maintain carrier adhesion to the developing roller. This precise parameter control resolves the contradiction between productivity and reliability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality by using a resin coating layer with specific local properties (containing inorganic oxide, specific thickness) on the carrier surface. This localized modification enhances toner adhesion and fluidity in the developing region while maintaining overall carrier stability and adhesion to the roller.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If dendritic titanium oxide is used in the coating layer to improve charge stability, then image density is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvecharge stabilityVSAvoidcoating process complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention specifies precise parameters for the dendritic titanium oxide including particle size (0.04-0.07 μm width, 0.2-0.3 μm length), specific surface area (70-90 m²/g), and coating amount (10-100 parts by weight per 100 parts silicone resin). These parameter specifications enable consistent charge stability while providing clear manufacturing guidelines that reduce complexity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses dendritic titanium oxide with specific local morphology (dendritic shape with defined dimensions) in the coating layer. This localized structural characteristic provides high charge stability and controlled toner interaction, while the well-defined parameters facilitate standardized manufacturing processes.

Inventive Principle:
Principle #3Local quality

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 agent effectively stabilizes toner supply to the photoreceptor, suppresses toner scattering, and maintains high image density over long periods, ensuring durable and high-quality image production.

Implementation Method 1

a frictional chargeability of the toner to be determined mainly based on a relation with the carrier is favorable

Methodology Applied
Scientific EffectFrictional charge: Triboelectric Effect

Implementation Method 2

the two-component developing system which develops the electrostatic latent image by making use of an electrostatic attraction

Methodology Applied
Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS7393622B2Two-component developing agent for electrophotography
Publication Date: 2008.07.01 SHARP KK

AI summary

A durable two-component developing agent for electrophotography is provided that can not only suppress scattering of a toner into an inside of an apparatus but also obtain a high image density and can stably obtain a high-quality image even in use for a long period of time. The two-component developing agent for electrophotography includes a toner, and a carrier. The carrier contains a core material and a coating layer formed on a surface thereof. The coating layer is a silicone resin coating layer containing dendritic titanium oxide. Therefore, it is possible to not only suppress scattering of the toner but also obtain a sufficient image density and to form a high-quality image without reducing the image density even in use for a long period of time.