Hexaboride Particle Silica Coating via Mediator Adsorption
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Solution Overview
Problem
Existing methods for surface treating hexaboride particles to enhance water resistance and dispersion stability in solar radiation shielding materials face challenges such as agglomeration, low mechanical and chemical stability of coatings, and difficulty in achieving uniform treatment at high concentrations, leading to degraded performance over time.
Innovation Solution
A method involving the use of an organo-metallic compound to disperse and promote polymerization of hydrolyzable silane compounds on hexaboride particles, followed by heating and solvent removal to form stable silica coatings, ensuring uniform coating and improved water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the concentration of alkoxysilane or surface treatment agent is increased to improve water resistance of fine hexaboride particles, then water resistance is improved, but agglomeration of particles occurs during hydrolysis and polycondensation reactions
Solution Approach 1:
The patent introduces a surfactant as an intermediary substance that mediates between the hexaboride particles and the alkoxysilane surface treatment agent. The surfactant adsorbs onto the particle surfaces first, creating a protective layer that prevents direct agglomeration during the hydrolysis and polycondensation reactions of the silane, while still allowing effective silica coating formation for improved water resistance
Solution Approach 2:
The patent applies preliminary action by first adsorbing the surfactant onto the hexaboride particle surfaces before adding the alkoxysilane surface treatment agent. This preliminary coating of surfactant prevents particle agglomeration during the subsequent silane hydrolysis and polycondensation reactions, enabling high concentrations of surface treatment agent to be used without causing agglomeration
2Stability of the object's composition
If mechanical dispersing treatment is applied after surface treatment to separate agglomerates, then particle dispersion is improved, but fine hexaboride particles are dissociated and exposed surface portions without silica coating are created
Solution Approach 1:
The surfactant acts as a mediator that allows mechanical dispersing treatment to be applied without compromising the silica coating. The surfactant-modified particle surfaces can be mechanically dispersed while the silica coating remains intact on the particle surfaces, preventing the creation of exposed surface portions
3Stability of the object's composition
If silica coating layers are formed on hexaboride particles to improve dispersion stability, then dispersion stability is improved, but mechanical strength and chemical stability of coatings are low without solvent removing and drying/firing steps
Solution Approach 1:
The patent applies continuity of useful action by integrating the surfactant adsorption, silica coating formation, and crosslinking reactions into a single continuous process. The surfactant remains on the particle surfaces throughout the process, and the silica coating forms continuously through hydrolysis and polycondensation reactions, eliminating the need for separate solvent removal and drying/firing steps while maintaining coating integrity
Solution Approach 2:
The patent utilizes parameter changes by controlling the pH, temperature, and concentration of reagents during the hydrolysis and polycondensation reactions of the alkoxysilane. By optimizing these parameters in the presence of the surfactant, the silica coating forms with high mechanical strength and chemical stability without requiring subsequent solvent removal or drying/firing steps
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 produces surface-coated hexaboride particles with enhanced water resistance and chemical stability, maintaining transparency and effectiveness as solar radiation shielding materials.
Implementation Method 1
adding an organo-metallic compound having a function for dispersing hexaboride particles and a function for promoting polymerization of a hydrolyzable silane compound, into a hexaboride-particle liquid dispersion... to thereby adsorb the organo-metallic compound onto surfaces of the hexaboride particles
Implementation Method 2
adding, into the liquid dispersion of the hexaboride particles having the organo-metallic compound adsorbed thereon, a hydrolyzable silane compound as a surface treatment agent, and water... to thereby coat a hydrolysis condensate of the hydrolyzable silane compound onto surfaces of the hexaboride particles
Implementation Method 3
in case that the hexaboride particles are so fine to exhibit an average primary particle diameter of 200nm or less, the method as described in the Japanese Patent Application Laid-Open Publication No. 2003-277045 tends to result in agglomeration of the fine hexaboride particles with one another in the course of hydrolysis reaction and polycondensation reaction
Implementation Method 4
heatingly maturing the hexaboride-particle liquid dispersion under a condition of a temperature lower than a thermal decomposition temperature of the organo-metallic compound, and then removing a solvent from the liquid dispersion
Data Source
AI summary
The present invention relates to a precursor of surface-coated hexaboride particles to be used in obtaining surface-coated hexaboride particles formed with silica coating layers, respectively, and a production method of such a precursor; and the production method comprises: a first step of adding an organo-metallic compound having a function for dispersing hexaboride particles and a function for promoting polymerization of a hydrolyzable silane compound, into a hexaboride-particle liquid dispersion comprising an organic solvent containing hexaboride particles dispersed therein, to thereby adsorb the organo-metallic compound onto surfaces of the hexaboride particles; a second step of adding, into the liquid dispersion, a hydrolyzable silane compound as a surface treatment agent, and water, to thereby coat a hydrolysis condensate of the hydrolyzable silane compound onto surfaces of the hexaboride particles; and a third step of heatingly maturing the liquid dispersion under a condition of a temperature lower than a thermal decomposition temperature of the organo-metallic compound, and then removing a solvent from the liquid dispersion, to form coatings derived from the surface treatment agent and coated on the hexaboride particles, respectively, the coatings each including a metal element contained in the organo-metallic compound, and silicon.