Organic Fine Particle Dispersion Stability via Controlled Heating

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Solution Overview

Problem

Current methods for producing fine organic pigment particles face challenges in achieving stable dispersions with uniform particle sizes, as existing techniques often result in low productivity, high energy consumption, and instability due to factors like overdispersion and variations in yield and molecular weight, particularly in the context of ink-jet inks and color filters.

Innovation Solution

A method involving heating an organic fine particle dispersion liquid containing a high molecular compound under controlled conditions through a channel, where the heating treatment is conducted at temperatures between 40°C to 100°C, promoting thermodynamic stability and cross-linking of the high molecular compound with functional groups, which enhances dispersion stability and maintains particle diameter consistency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If pigment particles are fined down to nanometer size to improve transparency and coloring power, then dispersion stability deteriorates due to increased specific surface area

Engineering Contradiction:
ImprovetransparencyVSAvoiddispersion stability
Core Design Contradiction:
Illumination intensityVSStability of the object's composition

Solution Approach 1:

A high molecular compound acts as an intermediary substance between the nanometer-sized pigment particles and the dispersion medium. This compound adsorbs onto the particle surfaces, providing steric stabilization that prevents aggregation despite the high specific surface area, thereby maintaining both transparency and dispersion stability simultaneously

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the molecular weight parameter of the stabilizing compound to high molecular weight range. This parameter change provides sufficient steric barrier to prevent aggregation of ultrafine particles while maintaining the desired nanometer size distribution for transparency and coloring power

Inventive Principle:
Principle #35Parameter changes

2Length of moving object

If crushing method is used to reduce pigment particle size to nanometer level, then productivity decreases and energy consumption increases

Engineering Contradiction:
Improveparticle diameterVSAvoidproductivity
Core Design Contradiction:
Length of moving objectVSProductivity

Solution Approach 1:

Instead of using the conventional approach of breaking down large particles into small ones (crushing method), the invention inverts the process by building up small particles from molecular precursors through polymerization reactions. This build-up method achieves nanometer-sized particles with high productivity and low energy consumption, avoiding the time-consuming and energy-intensive crushing process

Inventive Principle:
Principle #13The other way round (Inversion)

3Length of moving object

If high energy is applied in crushing method to reduce particle size, then overdispersion occurs causing thickening phenomenon

Engineering Contradiction:
Improveparticle diameterVSAvoidoverdispersion
Core Design Contradiction:
Length of moving objectVSObject-generated harmful factors

Solution Approach 1:

The invention replaces the mechanical crushing system with a chemical polymerization system. By substituting mechanical energy input with controlled chemical reactions, the process achieves particle size reduction without applying excessive energy that would cause overdispersion and thickening, maintaining stable dispersion characteristics

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Ease of manufacture

If batch method in flask is used for polymerization, then temperature control becomes difficult causing quality variations

Engineering Contradiction:
Improveease of operationVSAvoidquality uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention segments the polymerization process into controlled stages within a continuous flow reactor system. By dividing the reaction into manageable segments with controlled residence times and temperature zones, the process achieves both ease of operation and consistent quality uniformity, avoiding the temperature control difficulties of batch methods

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention implements continuous polymerization reaction instead of batch processing. The continuous flow through the reactor ensures constant temperature control and steady-state reaction conditions, eliminating the temperature fluctuations and quality variations inherent in batch flask methods while maintaining operational simplicity

Inventive Principle:
Principle #20Continuity of useful action

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

This approach enables the production of stable organic fine particle dispersions with particle diameters between 10 nm to 100 nm, improving dispersion stability, preventing viscosity increases, and enhancing the discharge capability of ink-jet inks while maintaining transparency and particle size consistency over time.

Implementation Method 1

cross-linking of the high molecular compound with functional groups, which enhances dispersion stability

Methodology Applied
Scientific EffectCross-linking:

Implementation Method 2

heating treatment under flowing through a channel, wherein the heating treatment is carried out at a temperature of 40°C to 100°C

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP2070990B1Method of producing an organic fine particle dispersion
Publication Date: 2012.09.12 FUJIFILM CORP
  • EP2070990B1 patent drawingFigure 1-1~1-2
  • EP2070990B1 patent drawingFigure 2-1~2-2
  • EP2070990B1 patent drawingFigure 2-3~3-1

AI summary

A method of producing a dispersion of organic fine particles having a volume average particle diameter (Mv) of 10 nm to 100 nm, which has the step of: subjecting an organic fine particle dispersion liquid containing a high molecular compound to heating treatment under flowing through a channel.