Metal Pigment Coating for Water-Based Paint Stability
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Solution Overview
Problem
Metal pigments, particularly aluminum pigments, face issues with corrosion and gas generation when used in aqueous solvents, leading to storage risks and poor coating film appearance due to aggregation and insufficient dispersibility in water-based paints and inks.
Innovation Solution
Adhering an organic carboxylic acid metal salt onto metal particles, such as aluminum, prevents gas generation and aggregation by forming a stable coating, which is achieved through mixing the metal particles with a first compound like a carboxylic acid, amine, or alcohol, and the organic carboxylic acid metal salt, without requiring hazardous or difficult-to-control processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an untreated metal pigment is blended into an aqueous solvent, then the metal pigment can be used in water-based paints and inks, but corrosion and gas generation occur leading to storage risks
Solution Approach 1:
The patent applies the intermediary principle by introducing a coating layer comprising a metal salt of a carboxylic acid between the aluminum metal particles and the aqueous environment. This coating layer acts as a mediator that prevents direct contact and reaction between water and aluminum, thereby eliminating corrosion and hydrogen gas generation while maintaining the pigment's functionality in water-based systems.
2Reliability
If an aluminum pigment is treated with chromic acid to prevent corrosion, then chemical stability improves, but environmental and operational difficulties arise due to sexavalent chromium compounds
Solution Approach 1:
The patent applies parameter changes by replacing the harmful sexavalent chromium compounds with environmentally benign metal salts of carboxylic acids. This substitution changes the chemical parameters of the treatment solution, achieving the same corrosion protection function without the toxicological and environmental drawbacks of chromium-based treatments.
3Reliability
If an aluminum pigment is treated with a polyacid peroxide coating to improve corrosion resistance, then chemical stability against water base paint improves, but dispersibility decreases causing seediness in coating films
Solution Approach 1:
The patent applies local quality by creating a coating layer with specific local characteristics - it provides sufficient corrosion resistance at the metal surface while maintaining appropriate surface properties that enable good dispersibility. The coating layer's composition (metal salt of carboxylic acid) is specifically chosen to balance these seemingly contradictory requirements, providing protection where needed while maintaining interfacial compatibility with the aqueous medium.
4Reliability
If polymolybdic acid peroxide is used to treat aluminum pigment, then water resistance improves, but aggregation occurs during preparation and storage due to strong acidity
Solution Approach 1:
The patent replaces the strongly acidic polymolybdic acid peroxide treatment with a milder, more stable coating approach using metal salts of carboxylic acids. This substitution eliminates the need for harsh acidic conditions while achieving comparable or superior water resistance, and crucially, avoids the aggregation problem that arises from the strong acidity of polymolybdic acid peroxide during storage.
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 solution provides a metal pigment with enhanced chemical stability, preventing gas generation and aggregation, and simplifies the production process while maintaining excellent water resistance and coating film quality.
Implementation Method 1
adhering an organic carboxylic acid metal salt onto metal particles, such as aluminum, prevents gas generation and aggregation by forming a stable coating
Implementation Method 2
moisture reacts with aluminum to generate hydrogen gas... an aluminum pigment treated with a polyacid peroxide... can be obtained by forming the above coating on the surface of the aluminum pigment
Implementation Method 3
insufficient dispersibility of the aluminum pigment, there is a problem in that seediness occurs when preparing a coating film... an aluminum pigment having a coating derived from polymolybdic acid peroxide formed thereon... exhibit excellent water resistance
Data Source
AI summary
The metal pigment of the present invention has a structure in which an organic carboxylic acid metal salt is adhered onto metal particles, and may also have a structure in which a first compound is adhered onto the metal particles, and the organic carboxylic acid metal salt is adhered onto the first compound.