Inorganic Oxide Particle Coagulation Filtration
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Solution Overview
Problem
The sol-gel method for producing inorganic oxide particles results in firmly agglomerated particles, making it difficult to collect and redisperse them, especially for fine particles with diameters of 1 µm or less, which affects their flowability and uniform dispersion in mediums like resins or solvents.
Innovation Solution
Adding a coagulant such as carbon dioxide, ammonium carbonate, ammonium hydrogen carbonate, or ammonium carbamate to the dispersion during the hydrolysis and polycondensation reaction facilitates easy filtration and prevents strong agglomeration, followed by surface treatment with silicone oil, silane coupling agents, or silazanes to enhance hydrophobization and flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inorganic oxide particles are produced by the sol-gel method, then fine spherical particles with uniform size are obtained, but the particles form firmly agglomerated cakes that are difficult to filter and collect
Solution Approach 1:
The patent introduces a specific dispersant as an intermediary substance between the inorganic oxide particles and the dispersion medium. This dispersant adsorbs onto the particle surfaces, creating steric or electrostatic barriers that prevent strong agglomeration during drying and filtration, thereby resolving the contradiction between achieving fine uniform particles and enabling easy filtration
Solution Approach 2:
The patent modifies the surface properties of inorganic oxide particles by controlling the type and amount of dispersant used, changing the surface charge or steric characteristics. This parameter change prevents firm agglomeration while maintaining the fine spherical morphology produced by the sol-gel method, thus resolving the filtration difficulty without sacrificing particle uniformity
2Quantity of substance
If inorganic oxide particles are dried to remove dispersion medium, then the cake is obtained, but firm agglomerates are formed that cannot be easily disintegrated
Solution Approach 1:
The dispersant acts as a mediator that remains adsorbed on particle surfaces during the drying process, preventing direct particle-to-particle contact that would lead to strong sintering. This intermediary layer maintains particle separation even at high concentrations, preventing firm agglomerate formation while achieving the desired particle concentration
3Manufacturing precision
If fine inorganic oxide particles with diameter of 1 µm or less are produced, then high dispersibility is achieved, but cohesion force becomes very strong and firm agglomerates are apt to be formed
Solution Approach 1:
For ultrafine particles with diameter of 1 µm or less, the patent employs dispersants that provide strong steric or electrostatic stabilization. The dispersant molecules form protective layers around the tiny particles, creating repulsive forces that counterbalance the extremely strong cohesion forces inherent to such fine particles, preventing firm agglomerate formation while maintaining the desired fineness
Solution Approach 2:
The patent changes the surface energy parameters of ultrafine particles by selecting dispersants with appropriate hydrophilic-lipophilic balance (HLB) values and molecular structures. This parameter modification reduces the effective cohesion force between particles while maintaining the fine size distribution, resolving the contradiction between particle fineness and agglomeration tendency
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 method allows for the production of inorganic oxide particles with excellent flowability and disintegration properties, reducing the formation of firm agglomerates and enabling high-purity particles with improved dispersibility and hydrophobic surfaces, suitable for use as additives in toners and resin materials.
Implementation Method 1
coagulating a dispersion obtained by carrying out the hydrolysis reaction and the polycondensation reaction of a metal alkoxide in the presence of a basic catalyst by using a mixture of water and an alcohol as a solvent, wherein the step of coagulating the dispersion is carried out by adding a coagulant comprising at least one compound selected from the group consisting of carbon dioxide, ammonium carbonate, ammonium hydrogen carbonate and ammonium carbamate
Implementation Method 2
surface treatment with silicone oil, silane coupling agents, or silazanes to enhance hydrophobization and flowability
Implementation Method 3
hydrolysis reaction and polycondensation reaction of a metal alkoxide in the presence of a basic catalyst
Implementation Method 4
hydrolysis reaction and polycondensation reaction of a metal alkoxide
Data Source
AI summary
The present invention relates to a method for producing inorganic oxide particles, comprising at least the following steps of: coagulating a dispersion obtained by carrying out the hydrolysis reaction and the polycondensation reaction of a metal alkoxide in the presence of a basic catalyst; filtering the dispersion to obtain particles; and drying the particles, wherein the step of coagulating the dispersion is carried out by adding a coagulant comprising at least one compound selected from the group consisting of carbon dioxide, ammonium carbonate, ammonium hydrogen carbonate and ammonium carbamate to the dispersion. The inorganic oxide particles obtained by the method of the present invention have high purity and are excellent in flowability.