Core-Shell Polyester Toner for Offset Resistance

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Solution Overview

Problem

Existing methods for manufacturing electrostatic charge image developing toner struggle to achieve high-quality images with excellent high-temperature offsetting resistance and low-temperature fixability while maintaining appropriate gloss, due to challenges in particle size distribution and energy consumption.

Innovation Solution

A method involving the use of an aqueous medium dispersion of crystalline and amorphous polyester resins, where core-shell type coagulated particles are formed and subsequently undergo radical polymerization to create a crosslinking structure, with a coagulation-termination agent added to control particle aggregation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a polyester resin with crosslinking structure is used to achieve low-temperature fixability, then low-temperature fixability is improved, but high-temperature offsetting resistance deteriorates

Engineering Contradiction:
Improvefixing temperatureVSAvoidoffsetting resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the core contains crystalline polyester resin for low-temperature fixability while the shell contains amorphous polyester resin with crosslinking structure for high-temperature offsetting resistance. Each part has different properties optimized for its specific function, resolving the contradiction between low-temperature fixability and high-temperature offsetting resistance.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining crystalline polyester resin and amorphous polyester resin with crosslinking structure in a core-shell configuration. This composite structure allows the toner to simultaneously exhibit low-temperature fixability (from crystalline core) and high-temperature offsetting resistance (from crosslinked amorphous shell), resolving the performance contradiction.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If the toner particle diameter is reduced to improve image quality, then image quality is improved, but manufacturing difficulty increases

Engineering Contradiction:
Improveimage qualityVSAvoidmanufacturing difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by pre-forming core particles of crystalline polyester resin with controlled small diameter before forming the shell. This preliminary preparation of core particles with desired size distribution facilitates the subsequent shell formation process and enables precise control of final toner particle diameter, improving both image quality and manufacturing ease.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent segments the toner particle manufacturing process into distinct stages: core particle formation, shell formation, and crosslinking. This segmentation allows independent optimization of each step, making it easier to control particle diameter and achieve high image quality while simplifying the overall manufacturing process.

Inventive Principle:
Principle #1Segmentation

3Reliability

If a polymerization method is used to create crosslinking structure, then low-temperature fixability and high-temperature offsetting resistance become compatible, but energy consumption increases

Engineering Contradiction:
Improvetemperature performance compatibilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by carefully controlling the polymerization conditions (temperature, time, initiator concentration) to achieve crosslinking at lower temperatures and shorter durations than conventional methods. This reduces energy consumption while still achieving the desired crosslinking structure for temperature performance compatibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a polymerization initiator as an intermediary to facilitate crosslinking at lower temperatures. The initiator enables the polymerization reaction to proceed under milder conditions, reducing energy consumption while achieving the crosslinked structure necessary for compatible low-temperature fixability and high-temperature offsetting resistance.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Manufacturing precision

If polyester resin is finely dispersed to improve image quality, then image quality is improved, but manufacturing difficulty increases

Engineering Contradiction:
Improveimage qualityVSAvoiddispersion difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent segments the dispersion challenge by first forming core particles with controlled size, then forming the shell around these pre-dispersed cores. This segmentation prevents aggregation during the dispersion process and achieves fine particle size distribution necessary for high image quality while simplifying manufacturing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by pre-forming core particles with desired size and distribution before shell formation. This preliminary dispersion of cores eliminates the need for extensive high-energy dispersion of the final crosslinked structure, making fine particle dispersion easier while maintaining high image quality.

Inventive Principle:
Principle #10Preliminary action

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

This method enables the production of toner with improved high-temperature offsetting resistance, low-temperature fixability, and appropriate gloss, while reducing energy consumption and enhancing image density gradation reproducibility.

Implementation Method 1

the polymerizable unsaturated bond is subjected to radical polymerization via action of a radical polymerization initiator on this core-shell type coagulated particle to form a crosslinking structure

Methodology Applied
Scientific EffectRadical polymerization: Photopolymerisation

Implementation Method 2

a coagulation-termination agent added to control particle aggregation

Methodology Applied
Scientific EffectCoagulation: Coagulation

Data Source

PatentUS8642242B2Electrostatic charge image developing toner and method of manufacturing the same
Publication Date: 2014.02.04 KONICA MINOLTA BUSINESS TECH INC

AI summary

Provided is a method of manufacturing toner by which the toner capable of forming high quality images and reproducing high density gradation, which exhibits an excellent high-temperature offsetting property together with excellent low-temperature fixability, and provides appropriate gloss with respect to images to be formed, can be stably prepared; and also provided is the toner. After conducting a step in which particles made of at least a crystalline polyester resin are coagulated to form core coagulated particles, and an unsaturated amorphous polyester resin particle is attached onto the surface of each of the core coagulated particles to form core-shell type coagulated particles, radical polymerization reaction is conducted by acting a radical polymerization initiator on the foregoing core-shell type coagulated particles to conduct a step in which a layer made of a crosslinking amorphous polyester resin is formed on the surface of each of the core coagulated particles.