Amorphous Silica Production via Iron-Free Vacuum Drying
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Solution Overview
Problem
Conventional methods for producing silica particles result in colorization due to iron contamination, leading to issues with purity and agglomeration, which are critical for applications in semiconductor sealing and LED materials where high purity and colorlessness are required.
Innovation Solution
The production of amorphous silica with a Fe content of 20 ppm or less is achieved through a process involving hydrolytic polycondensation of silicon alkoxide, followed by vacuum drying using a specifically configured heating tube and subsequent firing at 800° C. to 1200° C., which reduces iron contamination and agglomeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a vacuum drying apparatus is used to dry silica particles, then productivity is improved and particles can be dried almost instantaneously without secondary agglomeration, but iron contamination occurs during the drying step causing colorization
Solution Approach 1:
The invention extracts and removes the harmful iron contamination from the system by replacing the iron-containing vacuum drying apparatus with an iron-free drying method, thereby eliminating the source of colorization while maintaining high productivity
Solution Approach 2:
The invention introduces an intermediary substance (iron-free drying agent or modified drying environment) to transfer the drying function without introducing iron contamination, allowing instantaneous drying without contact with iron-containing components
2Manufacturing precision
If conventional drying methods are used to avoid iron contamination, then purity is improved, but secondary agglomeration occurs during drying
Solution Approach 1:
The invention changes the physical parameters of the drying process (temperature, pressure, humidity control) to achieve rapid drying that prevents secondary agglomeration while maintaining particle purity and monodispersity
Solution Approach 2:
The invention performs preliminary surface treatment or stabilization of silica particles before drying to prevent agglomeration during the drying process, ensuring particles remain dispersed and maintain their individual characteristics
3Manufacturing precision
If silica particles are dried slowly to prevent contamination, then purity is improved, but production time increases and productivity decreases
Solution Approach 1:
The invention rushes through the drying process by implementing rapid drying conditions that complete evaporation quickly, skipping the prolonged drying period that would otherwise be needed to ensure complete moisture removal, thereby achieving both purity and speed
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 process produces silica particles with low iron content, low hygroscopicity, and a sharp particle size distribution, suitable for high-purity applications in semiconductor sealing and LED materials, ensuring minimal colorization and improved durability of the final products.
Implementation Method 1
drying a slurry of a hydrolysis-polycondensation product of a silicon alkoxide
Implementation Method 2
vacuum drying apparatus having a heating tube which is externally heated and retained in reduced pressure
Implementation Method 3
firing the obtained dried particles at 800° C. to 1200° C.
Data Source
AI summary
Provided are amorphous silica particles for application to industrial fields where there are increasing desires for high purity and colorlessness. The amorphous silica particles are produced through the steps of hydrolysis of an alkoxide, vacuum drying, and firing. The amorphous silica particles have been reduced in coloration and in Fe content, which is causative of coloration of the silica, and can meet the desires. The amorphous silica is characterized by having an Fe content of 20 ppm or less.