Electrostatic Toner Set Crystallization Temperature Control

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Solution Overview

Problem

Existing electrostatic image developing toner sets experience issues with hot offset (toner particles melting excessively to adhere to the fusing member) and cold offset (toner particles failing to melt sufficiently due to insufficient heat) during the fixing process, particularly when forming images on varying paper thicknesses.

Innovation Solution

The toner set includes yellow, magenta, cyan, and black toners with specific crystallization temperature ranges: a first toner with a crystallization temperature between 80°C and 95°C and a second toner with a crystallization temperature between 60°C and 75°C, along with a controlled difference in crystallization temperatures to optimize heat absorption and release, reducing both hot and cold offset.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If toner particles are heated to high temperature to ensure sufficient melting and transfer to fusing member, then cold offset is reduced, but hot offset occurs due to excessive melting and adhesion to fusing member

Engineering Contradiction:
Improveimage fixation qualityVSAvoidhot offset
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The toner set is segmented into multiple toners (yellow, magenta, cyan, black, first transparent/dye toner, second transparent/dye toner) with different crystallization temperatures. This segmentation allows each toner to be optimized for specific temperature ranges, enabling the system to handle both hot and cold offset issues that would be difficult to address with a single uniform toner formulation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the crystallization temperature parameter of different toners to specific ranges (first toner: 80-95°C, second toner: 60-75°C, YMCK toners: controlled differences). By precisely controlling these thermal parameters, the toners exhibit predictable melting and solidification behaviors that prevent both excessive melting (hot offset) and insufficient melting (cold offset) during the fixing process.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If toner particles are heated to low temperature to prevent excessive melting and adhesion to fusing member, then hot offset is reduced, but cold offset occurs due to insufficient melting and transfer to fusing member

Engineering Contradiction:
Improvehot offsetVSAvoidimage fixation quality
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention changes the crystallization temperature parameter of different toners to specific ranges (first toner: 80-95°C, second toner: 60-75°C, YMCK toners: controlled differences). By precisely controlling these thermal parameters, the toners exhibit predictable melting and solidification behaviors that prevent both excessive melting (hot offset) and insufficient melting (cold offset) during the fixing process.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention utilizes phase transitions (melting and solidification) of toner particles at controlled crystallization temperatures. During fixing, toners undergo phase transition from solid to liquid state, and during transfer, they transition back to solid state. By controlling the crystallization temperature ranges and differences between toners, the phase transitions occur at optimal times, preventing both hot and cold offset.

Inventive Principle:
Principle #36Phase transitions

3Ease of manufacture

If uniform crystallization temperature is used for all toners, then manufacturing simplicity is maintained, but both hot and cold offset cannot be simultaneously reduced

Engineering Contradiction:
Improvetoner formulation simplicityVSAvoidimage fixation quality
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The toner set is segmented into multiple toners (yellow, magenta, cyan, black, first transparent/dye toner, second transparent/dye toner) with different crystallization temperatures. This segmentation allows each toner to be optimized for specific temperature ranges, enabling the system to handle both hot and cold offset issues that would be difficult to address with a single uniform toner formulation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the crystallization temperature parameter of different toners to specific ranges (first toner: 80-95°C, second toner: 60-75°C, YMCK toners: controlled differences). By precisely controlling these thermal parameters, the toners exhibit predictable melting and solidification behaviors that prevent both hot and cold offset during the fixing process.

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 optimized crystallization temperature ranges and controlled differences effectively reduce both hot and cold offset occurrences, ensuring consistent image fixation across different paper thicknesses and improving image quality.

Implementation Method 1

a first toner, the first toner being a dye toner or a transparent toner, the first toner having a crystallization temperature T1 of 80°C or more and 95°C or less; and a second toner, the second toner being a dye toner or a transparent toner, the second toner having a crystallization temperature T2 of 60°C or more and 75°C or less

Methodology Applied
Scientific EffectCrystallization: Crystallisation

Data Source

PatentEP4530726A1Electrostatic image developing toner set, electrostatic image developer set, toner cartridge set, process cartridge, image forming apparatus, and image forming method
Publication Date: 2025.04.02 FUJIFILM BUSINESS INNOVATION CORP
  • EP4530726A1 patent drawingFigure 1
  • EP4530726A1 patent drawingFigure 2
  • EP4530726A1 patent drawing

AI summary

An electrostatic image developing toner set includes a yellow toner including a yellow pigment; a magenta toner including a magenta pigment; a cyan toner including a cyan pigment; a black toner including a black pigment; a first toner that is a dye toner or a transparent toner, the first toner having a crystallization temperature T1 of 80°C or more and 95°C or less; and a second toner that is a dye toner or a transparent toner, the second toner having a crystallization temperature T2 of 60°C or more and 75°C or less.