Surface-Modified Silica Particle Size Control via High-Pressure Milling
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Solution Overview
Problem
Existing methods for producing surface-modified silicon dioxide particles face limitations such as restricted hydrophobization in aqueous phases, particle size dependence on initial aggregation, and inability to redisperse the modified particles without compromising surface modification, leading to incomplete coverage and reduced performance in applications like toner compositions and paints.
Innovation Solution
A method involving high-pressure grinding of a predispersion to create a dispersion with surface-modified silicon dioxide particles connected via Si-O-Si bonds, using organosilicon compounds with silicon-carbon bonds and functional groups that react with existing reactive groups on the particles, allowing for partial or complete modification and maintaining re-dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silicon dioxide particles are produced by gas-phase processes, then production efficiency is improved, but particle aggregation and agglomeration occur leading to larger particle sizes
Solution Approach 1:
The patent applies preliminary action by pre-modifying the surface of silicon dioxide particles with hydrophilic surface-modifying agents before dispersion. This pre-modification creates a protective layer that prevents aggregation during subsequent high-pressure homogenization, enabling efficient particle size reduction to below 100 nm while maintaining production efficiency.
Solution Approach 2:
The patent utilizes parameter changes by transitioning particles from aggregated states to dispersed states through high-pressure homogenization. The process changes pressure parameters (applying high pressure followed rapid decompression) and surface chemistry parameters (adding surface-modifying agents) to achieve controlled particle size reduction and prevent re-aggregation.
2Ease of operation
If surface modification is performed in aqueous phase, then ease of operation is improved, but degree of hydrophobization is limited
Solution Approach 1:
The patent uses hydrophilic surface-modifying agents as intermediaries that first attach to the silicon dioxide particle surfaces in aqueous phase, creating a hydrophilic layer. This intermediary layer then enables subsequent attachment of hydrophobic components, achieving both ease of aqueous phase processing and high degree of hydrophobization through multi-step surface modification.
3Manufacturing precision
If particle size is reduced below 100 nm, then surface modification completeness is improved, but particle aggregation increases
Solution Approach 1:
The patent creates composite structures by combining silicon dioxide particles with hydrophilic surface-modifying agents to form a stable core-shell structure. The hydrophilic shell layer provides steric stabilization that prevents aggregation of the reduced-size particles, enabling maintenance of particle sizes below 100 nm with complete surface modification while preventing aggregation through the protective composite structure.
4Manufacturing precision
If liquid phase is separated after surface modification, then particle isolation is improved, but surface modification uniformity decreases
Solution Approach 1:
The patent maintains continuity of useful action by performing surface modification continuously during the dispersion process rather than as a separate step. The surface-modifying agents are added to the predispersion before high-pressure homogenization, ensuring uniform surface modification occurs throughout the particle size reduction process, and the modified particles remain suspended in the liquid phase eliminating the need for separation 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-modified silicon dioxide particles with average diameters of at most 100 nm, ensuring complete or partial surface modification and maintaining re-dispersibility, enhancing their hydrophobic or hydrophilic properties and performance in various applications.
Implementation Method 1
surface-modified silicon dioxide particles, which are at least partially aggregated, are linked to the surface-modifying component via Si-O-Si bonds
Implementation Method 2
contains one or more organosilicon compounds, which have at least one silicon-carbon bond and at least one functional group which can react with the reactive groups to form a covalent Si-O-Si bond
Implementation Method 3
High-pressure milling of the pre-dispersion to form a dispersion
Data Source
AI summary
Producing surface-modified silicon dioxide particles with an average particle diameter of 100 nm comprises providing a predispersion, high pressure grinding the predispersion under the formation of a dispersion and separating liquid phase of the dispersion, where the predispersion contains: surface modified silicon dioxide particles that are at least partially aggregated and exhibit reactive groups on their surface; one or more organosilicon compounds that exhibit at least a silicon-carbon bond and at least one functional group; and one or more solvents. Producing surface-modified silicon dioxide particles with an average particle diameter of 100 nm comprises providing a predispersion, high pressure grinding the predispersion under the formation of a dispersion and separating liquid phase of the dispersion, where the predispersion contains: surface modified silicon dioxide particles that are at least partially aggregated, connected with the surface modified components via silicon-oxygen-silicon bonds and exhibit reactive groups on their surface; one or more organosilicon compounds that exhibit at least a silicon-carbon bond and at least one functional group that is reacted with reactive groups with the formation of covalent silicon-oxygen-silicon bond; and one or more solvents. An independent claim is included for the surface-modified silicon dioxide particles, obtained by the above process.