External Toner Additive with Embedded Inorganic Particles

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Solution Overview

Problem

Current toner additives for electrophotographic image-forming methods face challenges in achieving low-temperature fixability while preventing back soiling and ensuring heat-resistant storage stability, especially at higher printer speeds.

Innovation Solution

An external toner additive comprising a resin fine particle with a crystalline resin and an inorganic fine particle embedded, where part of the inorganic fine particle is exposed on the surface, with specific temperature peak criteria in differential scanning calorimetry to enhance adhesion and recrystallization, reducing back soiling and improving fixability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If crystalline resin fine particles are added to improve low-temperature fixability, then low-temperature fixability is improved, but charge distribution becomes uneven and developing performance decreases

Engineering Contradiction:

Improvelow-temperature fixabilityVSAvoiddeveloping performance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The invention uses a composite particle structure consisting of a resin fine particle core with an inorganic fine particle embedded in it. This composite structure combines the low-temperature fixability of crystalline resin with the charge stability of inorganic particles, resolving the contradiction between improving fixability and maintaining developing performance.

Inventive Principle:

Principle #40Composite materials

2Temperature

If resin fine particles with lower recrystallinity are used to improve low-temperature fixability, then low-temperature fixability is improved, but toner does not cohere easily and back soiling increases

Engineering Contradiction:

Improvelow-temperature fixabilityVSAvoidback soiling

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The composite particle structure combines resin fine particles optimized for low-temperature fixability with inorganic fine particles that provide coherency and reduce back soiling. The inorganic component compensates for the reduced coherency of low-recrystallinity resin, allowing both objectives to be achieved simultaneously.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The inorganic fine particle is embedded in specific regions of the resin fine particle, creating local variations in properties. The exposed inorganic particle surfaces provide coherency and prevent back soiling, while the resin portions maintain low-temperature fixability.

Inventive Principle:

Principle #3Local quality

3Reliability

If inorganic fine particles are embedded in resin fine particles to improve developing performance, then developing performance is improved, but low-temperature fixability at high speeds is not improved

Engineering Contradiction:

Improvedeveloping performanceVSAvoidlow-temperature fixability at high speeds

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The composite structure combines inorganic fine particles for developing performance with resin fine particles specifically selected for low-temperature fixability. The resin component has a melting point and crystallization characteristics that enable sharp melting at high speeds, while the inorganic component maintains developing performance.

Inventive Principle:

Principle #40Composite materials

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 external toner additive effectively reduces back soiling and enhances low-temperature fixability and heat-resistant storage stability, even at higher printer speeds, by optimizing the melting and recrystallization properties of the toner.

Implementation Method 1

the maximum endothermic peak temperature T1 (° C.) during the first temperature increase and the maximum exothermic peak temperature T2 (° C.) during the first temperature decrease satisfy the following formulae (1) to (3) below

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

optimizing the melting and recrystallization properties of the toner

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 4

enhances low-temperature fixability and heat-resistant storage stability, even at higher printer speeds, by optimizing the melting and recrystallization properties of the toner

Methodology Applied

Scientific EffectRecrystallization: Crystallisation

Data Source

PatentUS10747134B2External toner additive, method for producing external toner additive, and toner

Publication Date: 2020.08.18 CANON KK

AI summary

An external toner additive having a resin fine particle containing a crystalline resin and an inorganic fine particle embedded in the resin fine particle, wherein part of the inorganic fine particle is exposed on the surface of the resin fine particle, and in differential scanning calorimetry of the external toner additive, the maximum endothermic peak temperature T1 (° C.) during a first temperature increase and the maximum exothermic peak temperature T2 (° C.) during a first temperature decrease satisfy the formulae (1) to (3) below, with measurement performed between −40° C. and 150° C. at a rate of increase of 10° C./min during the first temperature increase and between 150° C. and −40° C. at a rate of decrease in temperature of 10° C./min during the first temperature decrease:T1-T2≤40.0 (1)50.0≤T1≤120.0 (2)10.0≤T2≤80.0 (3).