Bismuth Vanadate Pigment Alkaline Resistance via Silane Coating
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Solution Overview
Problem
Bismuth vanadate pigments exhibit poor alkaline resistance, leading to discoloration in high pH environments, limiting their use in water-based paints and architectural coatings, despite their excellent coloristic properties and chemical resistance.
Innovation Solution
Treatment of bismuth vanadate pigments with functionalized silanes of the formula R-Si(OR')3, where R is an alkyl group with more than 10 carbon atoms and R' is a methyl or ethyl group, before or after spray drying, to enhance alkaline stability, combined with optional chelating agents like polyacrylate or polyglycosides, to improve dispersability and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bismuth vanadate pigments are used in water-based paints and architectural coatings, then excellent coloristic properties and chemical resistance are achieved, but poor alkaline resistance leads to discoloration in high pH environments
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the bismuth vanadate pigment particles and the alkaline environment. The silane forms a protective interface layer that mediates the interaction, preventing direct contact between the pigment and harmful alkali, thus eliminating discoloration while preserving color strength
Solution Approach 2:
The invention creates a composite structure by coating bismuth vanadate pigment particles with silane. This composite material combines the excellent coloristic properties of bismuth vanadate with the alkaline resistance of silane, achieving both desired color performance and improved stability in high pH environments
2Reliability
If conventional coating methods are used, then manufacturing simplicity is maintained, but alkaline resistance remains insufficient for high pH architectural coatings
Solution Approach 1:
The silane coating is applied as a preliminary treatment to the bismuth vanadate pigment before final incorporation into the paint formulation. This preliminary action of coating the pigment particles ensures alkaline resistance is built-in at the particle level, simplifying the overall manufacturing process while achieving the required reliability
Solution Approach 2:
The invention changes the chemical parameters of the pigment surface by introducing silane functional groups. This parameter change at the molecular level transforms the surface properties to be alkali-resistant, enabling the pigment to withstand high pH environments without requiring complex process modifications
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 significantly enhances the alkaline resistance of bismuth vanadate pigments, maintaining color strength and preventing discoloration, making them suitable for high alkaline architectural coatings without compromising color properties.
Implementation Method 1
Treatment of bismuth vanadate pigments with functionalized silanes of the formula R-Si(OR')3
Implementation Method 2
Treatment of bismuth vanadate pigments with functionalized silanes of the formula R-Si(OR')3, where R is an alkyl group with more than 10 carbon atoms
Data Source
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AI summary
The present invention is directed to a method for manufacturing a bismuth vanadate pigment having an improved alkaline resistance, the method comprising: i) obtaining a dried bismuth vanadate pigment; ii) encapsulation of the bismuth vanadate pigment using a functionalized silane of the general formula R-Si(OR')3 wherein R is an alkyl group; and R' is a methyl or ethyl group; iii) final processing of the encapsulated pigment; and v) drying of the pigment. In addition, the present invention is directed to a bismuth vanadate pigment encapsulated with a functionalized silane of the general formula R-Si(OR')3 wherein R is an alkyl group; and R' is a methyl or ethyl group.