Resin Particle Polymerization With Aqueous Cooling for Coarse Powder Control

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Solution Overview

Problem

Existing methods for producing resin particles and electrostatic charge image developing toner face challenges in suppressing the generation of coarse powder, particularly when using styrene-based and (meth)acrylic acid-based monomers, due to temperature variations during polymerization.

Innovation Solution

A method involving the addition of a monomer-containing emulsified liquid to an aqueous mother medium followed by an aqueous medium for cooling, maintaining the temperature of the aqueous mother medium within a specific range, and controlling the reaction solution's temperature to suppress coarse powder generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling water is supplied to the jacket portion during polymerization, then the polymerization temperature can be maintained, but temperature variations still occur causing coarse powder generation

Engineering Contradiction:
Improvepolymerization temperatureVSAvoidparticle size uniformity
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

An aqueous medium for cooling is introduced as an intermediary substance to replace direct jacket cooling. This medium is added directly to the reaction mixture, allowing heat absorption through thermal conduction within the bulk phase, which provides more uniform temperature distribution and eliminates the temperature gradients caused by jacket cooling

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cooling method is changed from external jacket cooling to internal aqueous medium addition. This parameter change in the cooling mechanism enables more effective temperature control by distributing cooling throughout the reaction mixture, preventing localized temperature variations that lead to coarse powder formation

Inventive Principle:
Principle #35Parameter changes

2Temperature

If the supply amount of cooling water is increased, then temperature control improves, but the complexity of temperature management increases

Engineering Contradiction:
Improvetemperature controlVSAvoidtemperature management system
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The aqueous medium for cooling performs dual functions: it serves as both the polymerization medium and the cooling agent. By adding this medium directly to the reaction mixture, the system self-regulates temperature through the inherent thermal properties of the aqueous phase, eliminating the need for complex external cooling control systems

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The aqueous medium for cooling serves multiple purposes simultaneously: it acts as the reaction medium, the heat transfer medium, and the temperature control agent. This multi-functionality simplifies the overall temperature management system by consolidating multiple roles into a single substance

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Effectively reduces temperature variations and suppresses the formation of coarse powder, ensuring consistent and high-quality resin particle production.

Implementation Method 1

adding an aqueous medium for cooling to the aqueous mother medium after completion of the addition of the monomer-containing emulsified liquid to the aqueous mother medium

Methodology Applied
Scientific EffectHeat absorption: Heat Sink

Implementation Method 2

adding a monomer-containing emulsified liquid containing polymerizable monomers and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomers

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentUS12454584B2Method of producing resin particles and method of producing electrostatic charge image developing toner
Publication Date: 2025.10.28 FUJIFILM BUSINESS INNOVATION CORP

AI summary

A method of producing resin particles includes a first step of adding a monomer-containing emulsified liquid that contains a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer; and a second step of adding an aqueous medium for cooling to the aqueous mother medium after completion of the addition of the monomer-containing emulsified liquid to the aqueous mother medium.