Recommendations for the use of gold powder dispersants
Recommendations for the use of gold powder dispersants
1. Selection of dispersants
Adaptability
Select dispersants according to the particle size, surface properties and application scenarios of gold powder. For example, ultrafine gold powder (such as nano-level) needs to choose dispersants with strong steric hindrance effects (such as high molecular polymers), while micron-level gold powder can use surfactant dispersants.
Avoid dispersants that react chemically with gold powder or solvents to ensure the chemical stability of the dispersant.
Dispersant type
Polymers: such as polyvinyl pyrrolidone (PVP), polyacrylates, etc., are suitable for aqueous or organic solvent systems.
Surfactants: such as sodium dodecyl sulfate, polyoxyethylene ether, etc., are suitable for reducing surface tension and improving wettability.
Ionic dispersants: such as anionic (such as phosphates) or cationic (such as quaternary ammonium salts), suitable for specific charge stabilization systems.
Dispersant dosage
It is recommended to determine the optimal dosage through experiments, usually 0.5%~2% of the mass of gold powder. Excessive addition may cause dispersant residues and affect the performance of gold powder.
2. Dispersion process optimization
Pretreatment
Before adding the dispersant, ensure that the surface of the gold powder is clean to avoid impurities interfering with the dispersion effect. The gold powder can be pretreated by ultrasonic cleaning or solvent washing.
Addition method
Step-by-step addition: Add the dispersant to the gold powder several times to avoid local concentrations that lead to agglomeration.
Solvent dilution: For high-viscosity systems, the dispersant can be dissolved in an appropriate amount of solvent first, and then the gold powder can be added gradually.
Mixing equipment
Use equipment such as high-speed dispersers, ultrasonic dispersers or ball mills to ensure that the dispersant is in full contact with the gold powder.
The mixing time and speed need to be adjusted according to the type of dispersant and the particle size of the gold powder to avoid excessive shearing that causes deformation of the gold powder.
3. Process condition control
Temperature
Control the dispersion temperature between 20-50℃ to avoid high temperature causing the dispersant to fail or the gold powder to oxidize.
pH value
Adjust the system pH value to the optimal range of the dispersant (e.g. anionic dispersants usually work best at pH 7-9).
Solid content
Control the solid content of gold powder between 20-60%. Too high solid content may reduce the dispersion effect.
4. Dispersion effect evaluation
Particle size distribution
Use a laser particle size analyzer to detect the particle size distribution of the dispersed gold powder to ensure that there are no large particle agglomerates.
Stability test
Let the dispersion stand for 24-48 hours to observe whether precipitation or stratification occurs.
Application performance verification
Apply the dispersed gold powder to the target system (such as coatings, inks, electronic pastes, etc.) to evaluate its dispersibility, fluidity and final performance.
5. Precautions
Dispersant residue
Dispersant residue may affect the conductivity, weather resistance and other properties of the gold powder. Excessive dispersant needs to be removed by washing or heat treatment.
Safety
Some dispersants may be irritating or toxic. Protective equipment must be worn during operation to avoid direct contact.
Storage conditions
The dispersed gold powder needs to be stored in a sealed manner to avoid moisture or oxidation.
6. Common problems and solutions
Agglomeration problem
Increase the amount of dispersant or adjust the pH value; use ultrasonic dispersion to assist treatment.
Uneven dispersion
Optimize the mixing process and extend the dispersion time; check whether the dispersant is ineffective.
Poor stability
Add a small amount of stabilizer (such as polyethylene glycol); reduce the solid content of the system.