Bismuth Vanadate Pigment Doping for Weatherfastness
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Solution Overview
Problem
There is a need for bismuth vanadate pigments with improved coloristics and performance properties, such as high chroma, high color strength, and excellent weatherfastness, while being free from toxicological concerns and replacing lead chromate pigments in yellow color applications.
Innovation Solution
A bismuth vanadate pigment doped with a combination of magnesium (Mg), aluminum (Al), and phosphorus (P), optionally with additional elements like calcium (Ca), strontium (Sr), barium (Ba), zirconium (Zr), molybdenum (Mo), or cerium (Ce), is produced through a process involving the treatment of an alkaline vanadate solution with an acidic bismuth salt solution in the presence of soluble salts of magnesium and aluminum, followed by calcination and grinding to form pigment particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bismuth vanadate pigment is doped with multiple elements (Mg, Al, P, and optional E) to improve coloristics and performance properties, then chroma, color strength, and weatherfastness are enhanced, but the manufacturing process complexity and precision requirements increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar ratios of doping elements (Mg: 0.001-0.2, Al: 0.001-0.2, P: 0.001-0.5, and optional E: 0-1.7) to achieve optimal coloristics and weatherfastness. The systematic variation of these compositional parameters allows tuning of pigment properties while maintaining manufacturing feasibility through defined ranges.
Solution Approach 2:
The patent creates a composite doped bismuth vanadate pigment by combining multiple elements (Bi, V, Mg, Al, P, and optional E) in a unified crystal structure. This composite approach enhances weatherfastness and color properties synergistically, as each element contributes specific functional benefits to the overall pigment performance.
2Object-affected harmful factors
If bismuth vanadate pigment is used as a non-toxic alternative to lead chromate, then toxicological safety is improved, but achieving equivalent or superior color performance (chroma, hiding power) becomes more challenging
Solution Approach 1:
The patent achieves superior color performance in non-toxic bismuth vanadate by optimizing compositional parameters, specifically doping with Mg (0.001-0.2 mol), Al (0.001-0.2 mol), and P (0.001-0.5 mol), along with optional elements. These parameter adjustments enhance chroma and hiding power to match or exceed lead chromate equivalents while maintaining low toxicity.
Solution Approach 2:
The patent applies local quality by introducing specific doping elements at controlled concentrations within the bismuth vanadate crystal structure. Each dopant (Mg, Al, P, and optional E) provides localized functional improvements to color properties and stability, allowing the pigment to achieve high chroma and weatherfastness without relying on toxic lead chromate composition.
3Stability of the object's composition
If stabilizing coatings are applied to bismuth vanadate pigment to improve thermal stability and chemical resistance, then performance properties are enhanced, but the manufacturing process steps and complexity increase
Solution Approach 1:
The patent merges the stabilization function directly into the pigment crystal structure through doping with Mg, Al, and P elements during synthesis. This integration eliminates the need for separate stabilizing coating steps, as the doped composition itself provides inherent thermal stability and chemical resistance, reducing manufacturing complexity while maintaining enhanced performance.
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 pigment exhibits high chroma, high color strength, and excellent weatherfastness, making it suitable for various applications as a non-toxic alternative to lead chromate pigments, with enhanced hiding power and resistance to heat and chemicals.
Implementation Method 1
treating an alkaline vanadate solution with an acidic bismuth salt solution in the presence of soluble salts of magnesium and aluminum and soluble phosphates
Implementation Method 2
to form a precipitate
Implementation Method 3
calcining the precipitate
Data Source
AI summary
A bismuth vanadate pigment is provided which pigment is doped with a combination of Mg, Al and P and optionally an element E, wherein the molar ratios of the Bi, V, Mg, Al, P and E correspond to a formula Bi Mga Alb Ec Vd Pe Of (I) wherein E is selected from the group consisting of Be, Ca, Sr, Ba, Zr, Mo, Ce and a combination thereof; 0.001 ≤ a ≤ 0.2; 0.001 ≤ b ≤ 0.2; 0 ≤ c ≤ 1.7; 0.5 ≤ d ≤ 2.3; 0.001 ≤ e ≤ 0.5; and f denotes the number of oxygen atoms for satisfying the valence requirements of the cations. The pigment may be used as colorant in various applications, especially in coloring high molecular weight organic material, for example, coating compositions, paints, printing inks, liquid inks, plastics, films, fibers, or glazes for ceramics or glass.