Core-Shell Toner with Crystalline Vinyl Resin for Stable Charging

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Solution Overview

Problem

Existing toners using crystalline vinyl resins exhibit excellent low-temperature fixability and heat-resistant storage stability but suffer from poor charging performance, especially when transported in uncontrolled temperature and humidity environments.

Innovation Solution

A toner composition featuring a core-shell structure, where the core comprises a crystalline vinyl resin with at least 5.0% by mass of a specific monomer unit, and the shell is an amorphous resin with a controlled solubility parameter difference to the core, ensuring stable charging performance across varying temperature and humidity conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a crystalline vinyl resin is used as the binder resin, then low-temperature fixability and heat-resistant storage stability are improved, but charging performance deteriorates

Engineering Contradiction:

Improvefixing temperatureVSAvoidcharging performance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The invention divides the toner particle into a core region containing the crystalline vinyl resin and an outer layer containing an amorphous resin with different solubility parameters. This segmentation allows the core to provide low-temperature fixability while the outer layer maintains charging performance, resolving the contradiction between fixing temperature and charging performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite resin system combining crystalline vinyl resin (for low-temperature fixability) with amorphous resin having different solubility parameters (for stable charging performance). This composite material approach allows both low-temperature fixing and reliable charging to coexist.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If a crystalline vinyl resin is used as the binder resin, then heat-resistant storage stability is improved, but charging performance deteriorates in uncontrolled temperature and humidity environments

Engineering Contradiction:

Improveheat-resistant storage stabilityVSAvoidcharging performance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The invention changes the solubility parameter of the amorphous resin in the outer layer to be different from that of the crystalline vinyl resin in the core. This parameter difference creates a gradient structure that stabilizes charging performance across varying temperature and humidity conditions while maintaining heat-resistant storage stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite resin system combines crystalline vinyl resin (providing heat-resistant storage stability) with amorphous resin of different solubility parameters (providing stable charging performance in varying environments). This composite structure resolves the contradiction between heat-resistant stability and charging reliability.

Inventive Principle:

Principle #40Composite materials

3Reliability

If an amorphous resin shell is added to improve charging performance, then charging performance is improved, but the structure becomes more complex

Engineering Contradiction:

Improvecharging performanceVSAvoidtoner structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention applies local quality by concentrating the amorphous resin with different solubility parameters in the outer layer region, while the core region maintains crystalline vinyl resin. This localized modification improves charging performance without requiring complete structural redesign, thus limiting complexity increase.

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 maintains excellent low-temperature fixability and heat-resistant storage stability while preventing fluctuations in charging performance, even under significant temperature and humidity changes, thereby enhancing its reliability for use in diverse environmental conditions.

Implementation Method 1

when the melting point is exceeded, the crystals melt suddenly, which is accompanied by a rapid drop in viscosity

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

crystalline resins having excellent sharp melt property attract attention as materials that exhibit low-temperature fixability

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 3

Crystalline vinyl resins have long-chain alkyl groups as side chains, and the long-chain alkyl groups in the side chains are oriented to each other and hence exhibit crystallinity

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS20250199429A1toner

Publication Date: 2025.06.19 CANON KK

AI summary

A toner including a toner particle, wherein the toner particle includes a core containing a binder resin, and a shell covering the core, the binder resin includes a crystalline vinyl resin (A), the crystalline vinyl resin (A) containing at least 5.0% by mass of a monomer unit (a) having at least two of alkyl group having 16 to 30 carbon atoms, the shell is an amorphous resin, and the SP value of the amorphous resin and the SP value of the crystalline vinyl resin (A) satisfy specific relationship.