Liquid Developer Toner Dispersion Stability and Resistivity

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Solution Overview

Problem

Existing liquid developers for electrophotographic systems face challenges with toner particle size variability and productivity, as well as reduced volume resistivity due to toner particle dispersing agents persisting in the insulating liquid.

Innovation Solution

A liquid developer comprising a carrier liquid with an SP value not exceeding 8.20, toner particles insoluble in the carrier liquid, and a toner particle dispersing agent with a primary amino group, where the toner particles contain a polyester resin with specific acid and molecular weight characteristics, and a polymer with controlled amine value, ensuring high dispersion stability and volume resistivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If toner particle dispersing agents are used to increase dispersion stability, then dispersion stability is improved, but volume resistivity deteriorates due to agents persisting in the insulating liquid

Engineering Contradiction:

Improvedispersion stabilityVSAvoidvolume resistivity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent removes harmful substances (toner particle dispersing agents) from the liquid developer system through extraction processes, eliminating the source of volume resistivity degradation while maintaining dispersion stability through alternative means

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces intermediary substances that mediate between toner particles and the carrier liquid, providing dispersion stability without the harmful persistence in the liquid that would reduce volume resistivity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If conventional liquid developer formulations are used, then image formation is achieved, but toner particle size changes over time

Engineering Contradiction:

Improveimage formation capabilityVSAvoidtoner particle size consistency

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent changes physical and chemical parameters of the liquid developer formulation, including carrier liquid properties and additive characteristics, to stabilize toner particle size and prevent temporal changes while maintaining image formation capability

Inventive Principle:

Principle #35Parameter changes

3Reliability

If aluminum silicate and magnesium oxide/aluminum oxide solid solutions are used to remove dispersing agents, then volume resistivity is improved, but productivity deteriorates

Engineering Contradiction:

Improvevolume resistivityVSAvoidmanufacturing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces mechanical/chemical solid solution methods with alternative approaches that achieve volume resistivity improvement through different mechanisms, eliminating the productivity losses associated with solid solution processing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution provides a liquid developer with improved dispersion stability and high volume resistivity, maintaining toner particle size consistency and enhancing image formation quality in electrophotographic devices.

Implementation Method 1

a toner particle dispersing agent, wherein the toner particle contains a polyester resin with an acid value of from 5 mg KOH/g to 50 mg KOH/g

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

a carrier liquid with an SP value of not more than 8.20; a toner particle that is insoluble in the carrier liquid

Methodology Applied

Scientific EffectSolubility parameter control: Solvation

Implementation Method 3

the toner particle dispersing agent is a polymer having a primary amino group, an amine value of the polymer having the primary amino group is from 30 mg KOH/g to 200 mg KOH/g

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Data Source

PatentUS11513448B2Liquid developer and method for manufacturing liquid developer

Publication Date: 2022.11.29 CANON KK

AI summary

Provided is a liquid developer containing a carrier liquid with an SP value of not more than 8.20, a toner particle that is insoluble in the carrier liquid, and a toner particle dispersing agent, wherein the toner particle contains a polyester resin with an acid value of from 5 mg KOH/g to 50 mg KOH/g, a number-average molecular weight of the polyester resin is from 3,500 to 20,000, the toner particle dispersing agent is a polymer having a primary amino group, an amine value of the polymer having the primary amino group is from 30 mg KOH/g to 200 mg KOH/g, and a ratio of a total number of acid groups in the polyester resin relative to a total number of amino groups in the polymer having the primary amino group is from 1.0 to 10.0.