Toner Particle Core-Shell Structure for Fixability and Storage

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Solution Overview

Problem

Existing toners for electrophotographic image forming methods face challenges in achieving both low-temperature fixability and high-speed fixability while maintaining excellent heat-resistant storage properties, particularly in the print-on-demand market where high-speed printing is emphasized.

Innovation Solution

A toner with a binder resin comprising a polyester segment derived from an aromatic diol and a dicarboxylic acid, where the content of the polyester segment with an aromatic diol component is higher near the surface than in the central portion, providing a specific concentration gradient structure that enhances low-temperature fixability and heat-resistant storage properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If a binder resin with low softening temperature is used to achieve low-temperature fixability, then energy consumption is reduced, but heat-resistant storage properties deteriorate

Engineering Contradiction:
Improveenergy consumptionVSAvoidheat-resistant storage properties
Core Design Contradiction:
Use of energy by stationary objectVSReliability

Solution Approach 1:

The invention applies local quality by creating a core-shell structure where the central portion contains crystalline polyester resin for heat resistance while the surface portion contains amorphous polyester resin for low-temperature fixability. This allows different regions of the toner particle to have different functional properties, resolving the contradiction between low-temperature fixability and heat-resistant storage properties

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention uses composite materials by combining crystalline polyester resin and amorphous polyester resin in a specific core-shell configuration. The crystalline polyester provides thermal stability and heat resistance, while the amorphous polyester provides low-temperature fixability, creating a composite toner that achieves both properties simultaneously

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If a crystalline polyester resin is used to achieve high-quality color images, then image quality is improved, but high-speed fixability cannot be achieved

Engineering Contradiction:
Improveimage qualityVSAvoidhigh-speed fixability
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The invention applies local quality by placing crystalline polyester resin in the central portion to ensure image quality and heat resistance, while placing amorphous polyester resin in the surface portion to enable high-speed fixability. This spatial differentiation allows both image quality and high-speed fixability to coexist

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention combines crystalline and amorphous polyester resins in a core-shell structure where the amorphous surface layer enables rapid melting and fixing at high speeds, while the crystalline core maintains image quality and prevents offset, achieving both high-speed fixability and high-quality images

Inventive Principle:
Principle #40Composite materials

3Temperature

If urea modification is applied to achieve low-temperature fixability, then fixability is improved, but heat-resistant storage properties are degraded

Engineering Contradiction:
Improvelow-temperature fixabilityVSAvoidheat-resistant storage properties
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The invention applies local quality by concentrating the urea-modified amorphous polyester resin in the surface portion where low-temperature fixability is needed, while keeping the central portion as unmodified crystalline polyester to maintain heat-resistant storage properties, thus avoiding the degradation caused by urea modification in the heat-resistant core

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 toner achieves adequate low-temperature fixability and high-speed fixability while maintaining excellent heat-resistant storage properties, preventing high-temperature offset phenomena and ensuring high-quality image formation.

Implementation Method 1

enhanced low-temperature fixability can be realized via a toner composed of a binder resin exhibiting a low softening temperature

Methodology Applied
Scientific EffectSoftening:

Implementation Method 2

the binder resin comprising a polyester segment containing an aromatic diol component, the polyester segment being derived from an aromatic diol and a dicarboxylic acid

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

the toner composed of a binder resin exhibiting a low softening temperature has the problem of poor heat-resistant storage properties

Methodology Applied
Scientific EffectCrystallinity: Crystallisation

Data Source

PatentUS7781136B2Toner and production method of the same
Publication Date: 2010.08.24 KONICA MINOLTA BUSINESS TECH INC

AI summary

A toner comprising toner particles containing a colorant and a binder resin, the binder resin comprising a polyester resin, wherein the polyester resin comprises at least a polyester segment containing an aromatic dial component, the polyester segment being derived from an aromatic diol and a dicarboxylic acid, wherein a content of the polyester segment containing an aromatic dial component is higher in a surface-portion of the toner particle than in a central portion of the toner particle.