Electrostatic Carrier Resin Layer Peeling Prevention

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Solution Overview

Problem

Existing carriers for electrostatic latent image developers in electrophotographic systems face challenges with image quality due to peeling of the coating layer, color staining, and reduced charge control, especially in high-speed, low-temperature fixing processes, leading to issues like toner scattering and background fog.

Innovation Solution

A carrier with a resin layer containing oxygen-deficient tungsten-doped tin (WTO) and magnesium or barium compound particles, where the exposed amount of these particles on the surface is controlled between 1.2 and 10.0 atomic %, ensuring stable charging ability and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a carrier with a resin coating layer is used to prevent toner filming and protect the photoconductor, then the carrier provides good charge control and protection, but the coating layer peels off as the number of sheets copied increases, leading to image quality degradation and color staining

Engineering Contradiction:
Improvecharge control stabilityVSAvoidservice life of carrier
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The coating layer is divided into multiple layers: a base coat layer containing carbon black particles for charge control, and an outer transparent resin layer for protection. This segmentation allows each layer to perform its specific function optimally while improving overall durability against peeling

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The carrier uses a composite coating structure combining carbon black particles embedded in a resin matrix, with additional transparent resin coating. This composite approach provides both the charge control properties of carbon black and the protective, peel-resistant properties of the resin layers

Inventive Principle:
Principle #40Composite materials

2Duration of action of stationary object

If the coating layer is made thinner to reduce peeling, then durability improves, but charge control ability decreases

Engineering Contradiction:
Improveresistance to peelingVSAvoidcharge control ability
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The coating is segmented into a thin base coat layer containing carbon black particles for charge control, and a separate transparent resin layer for protection. This allows the charge-control layer to remain thin (reducing peeling) while the protective layer provides durability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The transparent resin layer acts as an intermediary between the carbon black coating and the external environment, providing protection against peeling and mechanical damage while allowing the underlying carbon black layer to maintain its charge control function

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If high-speed printing is performed with low imaging area ratios, then productivity increases, but toner scattering and background fog occur due to insufficient charge control

Engineering Contradiction:
Improveprinting speedVSAvoidimage quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The carrier particles are given a specific size range (20-45 μm) and the coating layer is optimized with specific carbon black content and resin composition. These parameter optimizations ensure stable charge control even during high-speed printing with low imaging area ratios, preventing toner scattering and background fog

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 solution provides a carrier that maintains consistent charge control and image quality, reducing toner scattering and carrier deposition, even under varying environmental conditions, and supports continuous high-speed printing with low imaging area ratios.

Implementation Method 1

The carrier is a bearing material that is mixed and stirred with the toner separately supplied inside a developing chamber to impart desired charge to the toner

Methodology Applied
Scientific EffectTriboelectric effect: Triboelectric Effect

Implementation Method 2

a resin layer covering the core particle, wherein the resin layer includes metal compound particles

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3432075B1Carrier for electrostatic latent image developer, two-component developer, replenishing developer, image forming device, and toner housing unit
Publication Date: 2021.05.05 RICOH CO LTD
  • EP3432075B1 patent drawingFigure 1
  • EP3432075B1 patent drawingFigure 2~3
  • EP3432075B1 patent drawing

AI summary

Provided is a carrier for a developer of an electrostatic latent image, the carrier including a core particle, and a resin layer covering the core particle, where the resin layer includes metal compound particles, wherein the metal compound particles include magnesium compound particles or barium compound particles, and an exposed amount B (atomic %)of the magnesium or the barium on a surface of the carrier particle satisfies a relationship below: 10.0≥B≥1.2.