Titanium Dioxide Pigment Composite with Aluminum Phosphate Coating
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Solution Overview
Problem
Titanium dioxide pigments face issues such as photoactivity leading to degradation, uneven coatings, poor dispersibility, and lacing problems in plastics, which affect their optical and processing properties, and current surface treatments often compromise between durability and dispersibility.
Innovation Solution
A process involving the deposition of a uniform thin layer of aluminum phosphate on titanium dioxide particles, generated in situ through a leaching process, combined with an anionic polyelectrolyte surfactant treatment, to create a hydrophobic, low-volatility, and low-dusting pigment with improved optical and processing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium dioxide particles are coated with hydrous oxide coatings (silica, alumina, zirconia) to reduce photoactivity and improve durability, then durability and chemical stability are improved, but dispersibility and processability deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the coating from conventional hydrous oxides (silica, alumina, zirconia) to a specific organic-inorganic hybrid coating system. This parameter change resolves the contradiction by providing both durability through the inorganic component and dispersibility through the organic component, eliminating the trade-off present in conventional coatings.
Solution Approach 2:
The patent applies a composite coating material comprising both inorganic (silane-based) and organic (polymer-based) components. This composite structure allows the coating to simultaneously provide durability through the inorganic network and dispersibility through the organic polymer chains, resolving the contradiction between these two properties.
2Stability of the object's composition
If titanium dioxide particles are coated with metal oxide coatings to reduce photochemical reactivity, then chemical stability is improved, but the pigments become more difficult to disperse in plastics
Solution Approach 1:
The patent uses a composite coating system combining inorganic silane components for chemical stability with organic polymer components for dispersibility. This composite approach allows simultaneous achievement of both chemical stability and ease of dispersion in plastic matrices.
Solution Approach 2:
The patent fundamentally changes the coating composition from purely inorganic metal oxides to an organic-inorganic hybrid system. This parameter change enables the coating to provide chemical stability through the inorganic silane network while maintaining dispersibility through the organic polymer component.
3Ease of operation
If titanium dioxide particles are spray dried to obtain free-flowing, low dusting powders, then flow characteristics are improved, but pigmentary properties deteriorate
Solution Approach 1:
The patent changes the surface treatment parameters to create a hydrophobic coating that prevents capillary condensation and interparticle bonding. This parameter change allows the pigment to maintain excellent flow characteristics without requiring spray drying, thereby preserving pigmentary properties.
Solution Approach 2:
The patent extracts the need for spray drying by providing free-flowing characteristics through surface coating alone. The hydrophobic coating eliminates capillary forces that cause poor flow, making the energy-intensive spray drying step unnecessary and preserving pigment quality.
4Manufacturing precision
If titanium dioxide particles are jet-milled to improve dispersibility and gloss, then pigmentary properties are improved, but energy consumption increases and dusting worsens
Solution Approach 1:
The patent performs preliminary surface treatment and hydrophobization of titanium dioxide particles before any size reduction or dispersing operations. This preliminary action provides adequate dispersibility through surface modification, eliminating or reducing the need for energy-intensive jet-milling while maintaining pigmentary properties.
Solution Approach 2:
The patent replaces the mechanical energy-intensive jet-milling process with a chemical/surface-based approach. By using surface coating and hydrophobization to achieve dispersibility, the patent substitutes mechanical size reduction with a surface chemistry solution, dramatically reducing energy consumption.
5Ease of operation
If titanium dioxide particles are jet-milled to achieve fine particle size, then dispersibility is improved, but flow characteristics worsen due to dusting
Solution Approach 1:
The patent changes the surface energy parameters of titanium dioxide particles through hydrophobic coating. This parameter change reduces interparticle forces and prevents dust generation, allowing fine particles to maintain excellent flow characteristics without the harmful dusting effect.
Solution Approach 2:
The patent converts the potential harm of fine particle dusting into a benefit by applying hydrophobic coating. The coating transforms the surface properties to reduce interparticle attraction, turning what would be a dusting problem into a free-flowing, easily handled material with excellent dispersibility.
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 titanium dioxide pigment exhibits enhanced durability, optical properties, and processing performance, including reduced photoreactivity and lacing resistance, while maintaining high titanium dioxide content and bulk density, making it suitable for various applications, especially in plastics.
Implementation Method 1
generated in situ through a leaching process
Implementation Method 2
combined with an anionic polyelectrolyte surfactant treatment
Data Source
AI summary
A process for producing an improved titanium dioxide pigment composite is provided, as are particles produced thereby. The process comprises producing a slurry comprising titanium dioxide particles, leaching alumina from the surface of the titanium dioxide particles in the presence of a soluble phosphate and precipitating aluminum phosphate from the slurry onto the surface of the titanium dioxide particles thereby forming a uniform coating of aluminum phosphate on the surfaces of the titanium dioxide particles. An anionic poly-electrolyte can be added to the resulting slurry. The slurry can then be treated such that the anionic poly-electrolyte forms an additional coating on the aluminum phosphate-coated titanium dioxide particles.