Titanium Dioxide Dispersion Viscosity Control via High-Energy Milling
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Solution Overview
Problem
Existing metal oxide dispersions for ceramics coatings have high viscosity, contain inorganic constituents that do not remove during tempering, and lack stability against sedimentation and thickening, making them unsuitable for high-solids content applications.
Innovation Solution
An aqueous dispersion comprising aggregated titanium dioxide powder with specific surface area, amino alcohol, and carboxylic acid, processed with high-energy milling at pressures above 500 bar to achieve low viscosity and stability, without additional inorganic constituents, allowing for a pourable and stable coating material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the solids content of titanium dioxide dispersion is increased, then the coating efficiency is improved, but the viscosity increases making the dispersion unpourable
Solution Approach 1:
The patent changes the chemical parameters by introducing specific amino alcohols and carboxylic acids as dispersing agents, and adjusts the particle size parameter through high-energy milling to achieve a mean volume-related diameter of less than 150 nm. These parameter changes enable the dispersion to maintain low viscosity even at high solids content of at least 20 wt.%, making it pourable at room temperature
Solution Approach 2:
The patent uses amino alcohols and carboxylic acids as intermediary substances to mediate between the titanium dioxide particles and the aqueous medium. These intermediaries prevent particle aggregation and reduce interparticle friction, enabling high solids content while maintaining low viscosity and pourability
2Stability of the object's composition
If inorganic constituents such as phosphates are used in metal oxide dispersions, then the dispersion stability is improved, but the constituents are not removed during tempering causing contamination
Solution Approach 1:
The patent extracts and removes harmful inorganic constituents like phosphates and polyphosphates from the dispersion system. Instead, it uses only amino alcohols and carboxylic acids as dispersing agents, which are completely removed during the tempering process, leaving no harmful residues on the ceramic or glass surfaces
Solution Approach 2:
The patent employs dispersing agents (amino alcohols and carboxylic acids) that are intentionally designed to be temporary and completely removable. These agents perform their function during application and drying, then are fully eliminated during tempering, unlike persistent inorganic constituents that contaminate the final product
3Duration of action of stationary object
If the dispersion is stored for extended periods, then the application time is extended, but sedimentation and thickening occur reducing stability
Solution Approach 1:
The patent performs preliminary action by subjecting the titanium dioxide particles to high-energy milling before dispersion, reducing them to a mean volume-related diameter of less than 150 nm. This preliminary size reduction prevents subsequent sedimentation and maintains stability during extended storage periods of at least one month
Solution Approach 2:
The patent establishes a feedback mechanism where amino alcohols and carboxylic acids continuously interact with titanium dioxide particle surfaces, providing steric and electrostatic stabilization. This dynamic feedback prevents particle aggregation and sedimentation throughout the storage period, maintaining dispersion homogeneity
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 resulting dispersion has a high solids content, low viscosity, and is stable against sedimentation and thickening for at least a month, enabling effective and stable application on ceramics and glass surfaces.
Implementation Method 1
producing a dispersion in which the aggregated titanium dioxide powder has a mean, volume-related aggregate diameter of less than 150 nm by grinding the pre-dispersion by means of a high-energy mill at a pressure of at least 500 bar
Implementation Method 2
at least one amino alcohol having from 1 to 6 carbon atoms, and at least one carboxylic acid from the group comprising dibasic carboxylic acids and/or hydroxycarboxylic acids having from 2 to 6 carbon atoms
Data Source
AI summary
An aqueous dispersion that can be used in the coating of glass, ceramics and metal surfaces is prepared by placing, in water, an aggregated titanium dioxide powder having a specific surface area of from 20 to 150 m2/g in such an amount that the desired dispersion contains at least 20 wt. % titanium dioxide, and at least one amino alcohol having from 1 to 6 carbon atoms, and at least one carboxylic acid selected from dibasic carboxylic acids and/or hydroxycarboxylic acids having from 2 to 6 carbon atoms. A pre-dispersion is produced by introducing energy in an amount of less than 200 kJ/m3. Then a dispersion is produced in which the aggregated titanium dioxide powder has a mean, volume-related aggregate diameter of less than 150 nm by grinding the pre-dispersion with a high-energy mill at a pressure of at least 500 bar.