Toner Set Gloss and Hot Offset via Crystalline Resin

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Solution Overview

Problem

Current toner sets for image forming fail to achieve high glossiness and sufficient fixability while maintaining hot offset resistance, as existing methods either lack stability or require special plates and cannot respond to variable data.

Innovation Solution

A toner set comprising a chromatic toner and a transparent toner, both incorporating a gel component insoluble to tetrahydrofuran due to a crosslinked structure, with adjusted amounts of tetrahydrofuran insoluble matter to ensure high glossiness and hot offset resistance, where the transparent toner has a higher amount of crystalline polyester resin than the chromatic toner.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a transparent toner with low melting point is used to achieve high glossiness, then gloss difference between image and non-image portions is reduced, but hot offset resistance deteriorates

Engineering Contradiction:
ImproveglossinessVSAvoidhot offset resistance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent applies local quality by giving different resin compositions to different toners: the transparent toner contains crystalline resin (1-20 mass%) to provide high glossiness, while the chromatic toner contains no crystalline resin to maintain low-temperature fixability. Each toner is optimized locally for its specific function.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining crystalline polyester resin with amorphous polyester resin in the transparent toner to achieve both high glossiness and hot offset resistance. The crystalline component provides gloss while the amorphous component ensures stability and resistance to hot offset.

Inventive Principle:
Principle #40Composite materials

2Stability of the object's composition

If transparent toner is applied to entire surface to reduce gloss difference, then uniform gloss is achieved, but hot offset resistance deteriorates

Engineering Contradiction:
Improveuniform glossVSAvoidhot offset resistance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies local quality by giving different resin compositions to different toners: the transparent toner contains crystalline resin (1-20 mass%) to provide high glossiness, while the chromatic toner contains no crystalline resin to maintain low-temperature fixability. Each toner is optimized locally for its specific function.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining crystalline polyester resin with amorphous polyester resin in the transparent toner to achieve both high glossiness and hot offset resistance. The crystalline component provides gloss while the amorphous component ensures stability and resistance to hot offset.

Inventive Principle:
Principle #40Composite materials

3Illumination intensity

If number average molecular weight of resin is adjusted to control gloss, then gloss control is achieved, but hot offset resistance and fixability stability cannot be maintained simultaneously

Engineering Contradiction:
Improvegloss controlVSAvoidfixability stability
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent changes parameters by controlling the number average molecular weight of the crystalline polyester resin within 500-5,000 and the amorphous polyester resin within 1,000-10,000. It also controls the weight average molecular weight ratio (Mw/Mn) of the crystalline resin to be 2-10. These parameter changes enable simultaneous achievement of gloss control and fixability stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining crystalline polyester resin with amorphous polyester resin in the transparent toner to achieve both high glossiness and hot offset resistance. The crystalline component provides gloss while the amorphous component ensures stability and resistance to hot offset.

Inventive Principle:
Principle #40Composite materials

4Illumination intensity

If transparent toner layer is formed on chromatic toner image, then high gloss image is achieved, but layer thickness increases and cold offset property requirement becomes more stringent

Engineering Contradiction:
Improvehigh gloss imageVSAvoidlayer thickness
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent changes parameters by controlling the number average molecular weight of the crystalline polyester resin within 500-5,000 and the amorphous polyester resin within 1,000-10,000. It also controls the weight average molecular weight ratio (Mw/Mn) of the crystalline resin to be 2-10. These parameter changes enable simultaneous achievement of gloss control and fixability stability.

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 toner set achieves high glossiness and sufficient fixability with improved hot offset resistance, allowing for distinct gloss differences between image and non-image regions without requiring special plates or compromising on low-temperature fixability.

Implementation Method 1

each toner incorporates a gel component which is insoluble to tetrahydrofuran due to a crosslinked structure present in the binder resin of the toner

Methodology Applied
Scientific EffectCrosslinked structure:

Implementation Method 2

the chromatic toner and the transparent toner each comprise a crystalline polyester resin

Methodology Applied
Scientific EffectCrystallization: Crystallisation

Data Source

PatentEP2667255B1Toner set, developer set, and image forming apparatus
Publication Date: 2016.05.18 RICOH CO LTD
  • EP2667255B1 patent drawingFigure 1
  • EP2667255B1 patent drawingFigure 2
  • EP2667255B1 patent drawing

AI summary

A toner set, including at least one chromatic toner containing a colorant; and a transparent toner containing no colorant, wherein the chromatic toner and the transparent toner each include a releasing agent and a binder resin, and wherein an amount of a tetrahydrofuran insoluble matter in the transparent toner is smaller than an amount of a tetrahydrofuran insoluble matter in the chromatic toner.