Colloidal Silica With Alkoxy Stabilization for Storage Stability
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Solution Overview
Problem
Existing methods for producing colloidal silica with small particle size and high abrasiveness are complex, costly, and result in increased particle aggregation and defects during storage, failing to meet the requirements of high purity and stability needed for electronic materials.
Innovation Solution
A production method involving a mother liquor with an alkaline catalyst and water, followed by the addition of alkoxysilane and an alkaline catalyst to produce colloidal silica with silica particles having a primary size of 20 nm or less, a high alkoxy group content, and a suppressed increase in secondary particle size during storage, using amines without hydroxyl groups as stabilizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If alkoxysilane is hydrolyzed to prepare a hydrolyzed solution and then added to mother liquor, then particles with excellent compactness and high particle density are formed, but the production process becomes multiple steps and complicated and costly
Solution Approach 1:
The patent combines the hydrolysis step and the particle formation step into a single integrated process. By adding alkoxysilane directly to the mother liquor containing alkaline catalyst, the hydrolysis and condensation occur simultaneously in one reactor, eliminating the need for separate hydrolysis and mixing steps while maintaining high particle density and compactness
Solution Approach 2:
The patent prepares the mother liquor with alkaline catalyst in advance, and then directly adds alkoxysilane to initiate hydrolysis and particle formation. This preliminary preparation of the catalytic environment allows the process to proceed in one step rather than requiring sequential processing of hydrolyzed solution
2Strength
If alkoxysilane is hydrolyzed to prepare a hydrolyzed solution, then high abrasiveness is achieved, but defects such as scratches undesirably increase on the substrate surface
Solution Approach 1:
The patent controls the particle size parameter to be 20 nm or less and maintains a high alkoxy group content (m/n ratio of 300 or more). By precisely controlling these parameters, the silica particles achieve high abrasiveness while their small size prevents them from causing scratches or defects on the substrate surface during polishing
3Strength
If silica particles with small average primary particle size are produced, then excellent abrasiveness is achieved, but the particles are likely to aggregate after storage resulting in increase in average secondary particle size
Solution Approach 1:
The patent maintains the alkoxy groups on the silica particle surfaces continuously present without complete hydrolysis. These persistent alkoxy groups provide ongoing steric and electrostatic stabilization, preventing particle aggregation during storage while preserving the small primary particle size necessary for high abrasiveness
Solution Approach 2:
The patent establishes a critical parameter threshold of m/n ratio (alkoxy group content divided by primary particle size) of 300 or more. This parameter control ensures that sufficiently high amounts of alkoxy groups remain on small particles (20 nm or less), providing continuous stabilization against aggregation during storage
4Stability of the object's composition
If dispersion stabilizer such as ammonia is added to produce silica with small particle size and excellent storage stability, then storage stability is improved, but high purity requirement for electronic materials is not met
Solution Approach 1:
The patent removes ammonia and other dispersion stabilizers from the system entirely. Instead, it uses the alkoxy groups inherently present on the silica particles (from the alkoxysilane precursor) as the stabilizing mechanism. This extraction of foreign stabilizing agents achieves both high purity required for electronic materials and adequate storage stability
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 colloidal silica with improved abrasiveness, reduced defects, and enhanced storage stability by maintaining small particle size and density, suitable for electronic material applications.
Implementation Method 1
a production method in which a hydrolyzed solution obtained by hydrolyzing an alkoxysilane is added to a mother liquor
Data Source
AI summary
Colloidal silica containing silica particles that have a small particle size (e.g., an average primary particle size of nm or less) and that contain alkoxy groups, and a method for producing the colloidal silica, are disclosed. The colloidal silica containing silica particles can have a small particle size and exhibit a suppressed increase in the average secondary particle size after storage. The colloidal silica containing silica particles wherein the silica particles have an average primary particle size of 20 nm or less, the silica particles have a ratio (m/n) of the content of alkoxy groups m (ppm) to the average primary particle size n (nm) of 300 or more, the silica particles have a particle density of 1.95 or more, and the silica particles have an increase rate of average secondary particle size of 12% or less in a storage stability test.