Under normal circumstances, the performance of aluminum hydroxide remains unchanged. However, to meet industry requirements, we first delve into some knowledge about surface modification before proceeding with the modification.
Section 1: Modification Methods
1. Utilizing silane coupling agents at a dosage of 0.5% to 3% of the treated aluminum hydroxide amount. Prior to use, dilute the coupling agent with ethanol in a 1:1 ratio. Apply the diluted coupling agent to the filler surface, then heat and continue stirring for 10 minutes at 95-150°C. At this point, a monomolecular film forms on the filler surface, transforming from hydrophilic to hydrophobic, and becomes relatively stable.
2. Utilizing Aluminate Coupling Agents: The coupling agent should be added to 1.5-2.5%, with the filler first mixed and dried in a high-speed mixer for 10-15 minutes to ensure moisture content is below 0.3%. Then, slowly add the measured, crushed coupling agent.
3. After adding the powdered filler, remove the moisture when the temperature reaches 90-100°C under high-speed stirring, then add the measured and diluted coupling agent solution. Stop the machine and discharge the material for use when the temperature reaches 105°C.
4. The coupling agent is diluted with an appropriate amount of an inert solvent and then sprayed onto the powder. The mixture is then blended and modified in a slow-speed kneader.
II. Modified Benefits
1. The addition of additives affected the surface properties of aluminum hydroxide crystals, thereby inhibiting secondary nucleation, resulting in the formation of sheet-like crystals as new secondary nuclei. It strengthened the aggregation of fine particles while also hindering the aggregation of larger particles; 2. There was also a significant inhibition on crystal growth.
3. Surface modification can effectively reduce the ATHRL value of powders, enhance the compatibility between the powder and unsaturated polyester, thereby significantly decreasing the viscosity of the blended material.
Alumina modification brings numerous benefits to the product itself, hence when modification is necessary, we can alter its performance and enhance its quality through modification.
