Defoaming agent performance test method
graduated cylinder method
The graduated cylinder method is mainly used in low viscosity coating systems and pure emulsion systems. Add a certain amount of about 20ml of the sample into a 50ml graduated cylinder with a stopper, then add a certain amount of defoaming agent as needed, cover the stopper, and turn over 20 times at a rate of 1 time/S. Then stop immediately and record the height of the foam. After letting it stand for a certain period of time, record the height of the foam again. Compare the recorded data with the data of various other defoaming agents. Applying this method can preliminarily estimate the defoaming property of the defoaming agent, but the measurement method determines that the accuracy of the measurement will not be too high.
high speed stirring method
Compared with the measuring cylinder method, the high-speed stirring method has the advantages of accurate measurement standards and wide application. The high-speed stirring method can be evaluated in two ways. Foam level measurement method, this method is suitable for low viscosity coating systems and emulsions; Pycnometer method, this method is suitable for high viscosity systems and emulsions.
Foam level measurement method
Add a certain amount of paint sample, such as 100ml, into a beaker with a minimum measurement scale of 1ml, add a certain amount of defoaming agent, and then use a high-speed stirring and dispersing machine to stir for a certain period of time at a certain speed, such as 3000~6000r/min, and wait for a certain period of time. Set. Observe the change of foam volume within a certain time interval and record it. The smaller the foam volume, the stronger the defoaming property of the defoaming agent, or observe the time it takes for the foam to reach a certain volume. The longer the time, the stronger the defoaming property of the defoaming agent. The weaker the sex.
Specific gravity cup method
Put a certain amount of paint sample (150~200g) into a beaker of a fixed size, and then use a high-speed stirring and dispersing machine to stir at a certain speed, such as 3000~6000r/min for a certain period of time, then stop stirring immediately, and Put the stirred paint sample into a pycnometer and measure its density. Measure again after a period of time, such as 15 minutes, and record 4 to 6 sets of data for comparative analysis.
Painting Experimental Method
After the performance evaluation of the defoaming agent, it is necessary to further test the impact of the defoaming agent on the quality of the paint film, such as whether there are shrinkage holes, changes in miscibility, gloss, etc. Use a 75um applicator to apply a layer of paint film on a clean glass plate, then observe whether there are shrinkage holes, and then use a gloss meter to measure its gloss.
storage stability method
Take a certain amount of defoaming agent sample and place it in a bottle with a lid, then place it in a constant temperature oven at 50°C. Take it out at regular intervals and test its various properties. Record 3 to 4 sets of data for comparison and analysis. It is generally believed that storage in a constant temperature drying oven at 50°C for 1 to 2 weeks is equivalent to 6 months of storage at room temperature.
