Phosphate Anti-Corrosive Pigment Crystallization for Lower Oil Absorption
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Solution Overview
Problem
Existing phosphate-containing anti-corrosion pigments have high oil absorption values due to fine, needle-shaped primary particles, limiting their concentration in coatings and leading to uneven distribution and porosity, which compromises corrosion protection.
Innovation Solution
A method involving the controlled reaction of hydroxyapatite or calcium-magnesium-phosphate particles with lime milk and phosphoric acid at specific pH and temperature conditions, followed by separation and drying, to produce phosphate-containing anti-corrosion pigments with reduced specific surface area and improved evenness of metal ion distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional precipitation methods are used to produce phosphate-containing anti-corrosion pigments, then the pigments can be manufactured with mixed metal phosphates, but the primary particles become very fine and needle-shaped with sub-μm size, resulting in high specific surface area and high oil absorption value (>30 g/100 g, usually >40 g/100 g)
Solution Approach 1:
The patent changes the crystallization parameters by controlling pH (6.0-13.0) and temperature (20-105°C) during precipitation, and by using specific metal ion ratios (Mg:Ca between 0.01-1.0) to transform the particle morphology from fine needles to more compact shapes with reduced specific surface area, thereby reducing oil absorption while maintaining homogeneous metal ion distribution
Solution Approach 2:
The patent creates composite calcium-magnesium-phosphate particles with specific structural characteristics where magnesium ions are incorporated into the hydroxyapatite crystal structure, forming a composite material with optimized properties that balance homogeneous metal distribution with reduced surface area and lower oil absorption values
2Stability of the object's composition
If the specific surface area of phosphate-containing anti-corrosion pigments is increased to improve dispersion, then more oil is needed to disperse the pigment evenly, resulting in higher oil absorption value and limiting the amount of pigment that can be introduced into the coating
Solution Approach 1:
By optimizing crystallization parameters including pH, temperature, and metal ion ratios, the patent produces particles with controlled morphology that achieve sufficient dispersion stability without excessive specific surface area, thereby reducing oil absorption and enabling higher pigment loading in coatings
3Ease of manufacture
If apatite powder and slightly soluble metal phosphate are physically mixed to produce phosphate-containing pigment, then the production process is simple, but the distribution of metal phosphate in the pigment is uneven and the synergistic effect is limited
Solution Approach 1:
The patent merges the precipitation processes by simultaneously precipitating apatite and metal phosphates in a single reaction step rather than separate physical mixing, allowing metal ions to be incorporated into the crystal structure during growth, which ensures homogeneous distribution while maintaining production efficiency
Solution Approach 2:
By controlling pH and temperature parameters during simultaneous precipitation, the patent optimizes the crystallization conditions to achieve uniform metal ion distribution within the particles, transforming the simple physical mixing approach into a controlled chemical process that delivers both simplicity and precision
4Quantity of substance
If apatite powder and slightly soluble metal phosphate with different solubilities are physically mixed, then the pigment can be produced with multiple metal phosphates, but individual areas dissolve away sooner upon reaction with water, causing the coating layer to become porous quickly
Solution Approach 1:
The patent combines multiple metal phosphates into a single homogeneous crystal structure during simultaneous precipitation, creating particles with uniform composition and controlled solubility characteristics, which prevents differential dissolution and maintains coating integrity over time
Solution Approach 2:
The patent creates composite calcium-magnesium-phosphate particles where multiple metal ions are incorporated into a unified crystal structure, producing a composite material with balanced solubility properties that ensures uniform dissolution behavior and sustained corrosion protection
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 results in phosphate-containing anti-corrosion pigments with lower oil absorption values, enabling higher concentrations in coatings and enhanced corrosion protection by reducing porosity and ensuring uniform distribution of metal ions.
Implementation Method 1
The three components are suspended in water, stirred at 60° C. for 1.5 hrs and the resulting product is filtered off. The simultaneous precipitation results in mixed metal phosphates that have a homogeneous distribution of the various metal ions.
Implementation Method 2
reacting the reaction mixture to form the phosphate-containing anti-corrosion pigment at a temperature in the range of 20° C. to 105° C. and at a pH value in the range of 6.0 to 13.0
Data Source
AI summary
The present invention relates to a method for producing a phosphate-containing anti-corrosive pigment, to the phosphate-containing anti-corrosive pigment obtainable by this method, and to the use of the phosphate-containing anti-corrosive pigment for passive protection against corrosion.