Metal Fine Particle Dispersion with Sub-50 Nm Size Stability
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Solution Overview
Problem
Existing methods for producing metal fine particles result in the formation of coarse particles larger than 100 nm, leading to deteriorated functions and properties, and poor dispersion stability due to flocculation, particularly when using polyol solvents like ethylene glycol.
Innovation Solution
A process involving the mixing of a metal oxide, a polymer with a hydrophilic group, and a dihydric alcohol represented by a specific general formula to control the cumulant average particle size of metal fine particles to not more than 50 nm, inhibiting the formation of coarse particles and enhancing dispersion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods using polyol solvents like ethylene glycol are used to produce metal fine particles, then the production process is simple, but coarse particles larger than 100 nm are formed and dispersion stability deteriorates due to flocculation
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by replacing conventional polyol solvents with a specific mixed solvent system comprising a carboxylic acid solvent and a polyol solvent in controlled proportions. This parameter change prevents flocculation and maintains dispersion stability while producing fine particles with controlled size distribution
Solution Approach 2:
The patent uses a composite solvent system combining carboxylic acid (e.g., acetic acid) and polyol (e.g., ethylene glycol) in specific ratios. This composite approach leverages the benefits of both solvents: the carboxylic acid prevents flocculation while the polyol controls particle growth, achieving both fine particle size and stable dispersion
2Manufacturing precision
If heat treatment under high temperature conditions is conducted to retrieve metal atoms from metal complex, then metal fine particles can be produced, but residual organic substances remain and require removal
Solution Approach 1:
The patent employs a disposable reducing agent (sodium borohydride) that completely decomposes during the reaction, leaving no residual organic substances. This replacing persistent organic reducing agents with a completely decomposable inorganic reducing agent eliminates the need for residual removal while maintaining efficient metal particle production
3Manufacturing precision
If metal fine particles are produced with smaller particle size to improve functions and properties, then particle functionality increases, but particles tend to flocculate and dispersion stability decreases
Solution Approach 1:
The patent changes the chemical environment parameters by introducing carboxylic acid to the solvent system, which alters the surface chemistry and electrostatic properties of the metal particles. This parameter change creates repulsive forces between particles, preventing flocculation and maintaining stable dispersion of fine particles
Solution Approach 2:
The carboxylic acid solvent acts as an intermediary substance that mediates between the metal particles and the polyol solvent. It forms a protective interface that prevents direct particle-particle contact and flocculation, enabling stable dispersion of fine particles
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 process achieves a high content of metal fine particles with a particle size of not more than 100 nm, improving dispersion stability and maintaining functional integrity.
Implementation Method 1
a process for producing a metal fine particle dispersion containing metal fine particles (a) dispersed with a polymer B, including the step 1 of mixing a metal oxide A, the polymer B and a compound C with each other
Implementation Method 2
the metal fine particles (a) have a cumulant average particle size of not more than 50 nm
Implementation Method 3
improving dispersion stability and maintaining functional integrity
Data Source
AI summary
The present invention relates to [1] a process for producing a metal fine particle dispersion containing metal fine particles (a) dispersed with a polymer B, including the step 1 of mixing a metal oxide A, the polymer B and a compound C with each other, in which the polymer B contains a hydrophilic group; the compound C is a dihydric alcohol represented by the general formula (1); and the metal fine particles (a) have a cumulant average particle size of not more than 50 nm, and [2] an ink containing the metal fine particle dispersion obtained by the production process described in the above [1].