Vapor Phase TiO2 Pigment Coating Process
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Solution Overview
Problem
The chloride process for producing titanium dioxide pigment requires additional wet treatment steps for surface modification, which increases costs and energy consumption, and results in debris and crystalline oxides, limiting the production of durable, non-yellowing, anatase-free particles with smaller sizes.
Innovation Solution
A vapor phase process involving the reaction of a vaporous titanium dioxide precursor with an oxygen-containing gas and a mixture of liquid or finely divided compounds at high temperatures, allowing for pyrogenic deposition of oxides on titanium dioxide particles, reducing the need for wet treatments and achieving a substantially anatase-free, durable pigment with smaller particle sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet treatment steps are used to deposit metal oxides on titanium dioxide surface, then pigment properties such as dispersion and durability are improved, but additional processing steps, energy consumption, and costs increase
Solution Approach 1:
The patent combines the base pigment production and surface treatment deposition into a single integrated vapor phase oxidation process. Metal oxide compounds are introduced into the reactor along with titanium tetrachloride and oxygen, allowing simultaneous formation of TiO2 particles and deposition of protective oxide coatings (such as Al2O3, SiO2, ZrO2) on their surfaces, thereby eliminating separate wet treatment steps
Solution Approach 2:
The patent changes the physical state and processing conditions by using vapor phase oxidation at high temperatures (1200-1600°C) instead of conventional wet chemical treatments. This parameter change allows for direct thermal decomposition and deposition of metal oxides onto the forming pigment particles, achieving surface modification without water-based processing
2Manufacturing precision
If wet treatment is used to deposit metal oxides, then surface treatment is achieved, but debris and crystalline oxides are produced, limiting production of high-quality anatase-free particles
Solution Approach 1:
The patent replaces wet chemical processing with vapor phase thermal oxidation. Metal oxide compounds are introduced in vapor or fine particle form and thermally decomposed during the oxidation process, allowing controlled deposition of amorphous oxide layers on TiO2 particles without the debris and crystalline structures associated with wet precipitation methods
Solution Approach 2:
The patent utilizes phase transitions of metal oxide compounds from solid or liquid precursors to gaseous or vaporized forms during heating, enabling controlled deposition onto forming particles. The thermal decomposition and oxidation occur in the vapor phase, allowing for cleaner particle formation without wet treatment byproducts
3Reliability
If additional wet treatment steps are added for surface modification, then pigment properties are optimized, but operating costs and equipment requirements increase
Solution Approach 1:
The patent merges multiple process functions into a single reactor system that performs base pigment production, metal oxide deposition, and particle formation simultaneously. By introducing metal oxide compounds into the oxidation reactor along with TiCl4 and oxygen, the system eliminates the need for separate wet treatment equipment and processing lines
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 effectively coats titanium dioxide particles with oxides, reducing debris and crystalline structures, enhancing durability and dispersion, while minimizing processing steps and costs, and producing a high-quality pigment suitable for exterior coatings and plastics.
Implementation Method 1
reacting a vaporous titanium dioxide precursor and an oxygen containing gas in a reactor
Implementation Method 2
the coating of oxide formed from the element is pyrogenically deposited
Data Source
AI summary
The present disclosure relates to a vapor phase process for producing a substantially anatase-free titanium dioxide pigment comprising: reacting a vaporous titanium dioxide precursor and an oxygen containing gas in a reactor; and introducing a mixture of liquid titanium dioxide precursor and a liquid or finely divided solid compound comprising a element selected from the group consisting of Li, Be, B, Na, Mg, Al, P, S, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, and Pb, into the reactor at a point downstream of the addition of the vaporous titanium dioxide precursor, and the oxygen containing gas, and at a process temperature of about 1200° C. to about 1600° C. to produce titanium dioxide particles that are coated by the oxide formed from the element.