Defoamer is a commonly used chemical agent in the chemical industry to eliminate bubbles. There are various types and qualities of defoamers. To test the performance of defoamers, the following methods are listed. There are several methods required for defoaming performance testing, including measuring cylinder method, circulation method, high-speed stirring method, vibration method, and bubbling method. Observe the changes in defoaming performance and paint film appearance after natural storage and high-temperature storage.
Defoamer detection method 1:The measuring cylinder method is applicable to the preliminary test of low viscosity coatings and lotion. In a 50ml measuring cylinder with a grinding plug, add 20~30ml of sample, and then add the amount of defoamer. Press the grinding plug tightly with your fingers and shake it violently back and forth for 20 times. After stopping, record the foam height immediately, record the foam height again at a certain interval, and then compare various defoamers. This method can be performed even with few samples, which is simple and convenient, but the results are crude and only suitable for preliminary screening of defoamers.
Defoamer testing method 2:The recycling method, as an industrial construction roller coating method or spray coating method, involves the remaining coating material falling into the receiver for recycling and reuse. Imitate the defoaming performance test method of the system. The height and flow rate of the falling material in the loop are constant, and the height of the material in the receiver is recorded at each time interval.
Defoamer testing method 3:The specific gravity cup method, i.e. static, is applicable to high viscosity coatings and lotion.. Specific gravity cup method: Weigh 150-200g of coating sample into a 200m container, add defoamer, and use a homogenizer to stir at a constant speed of 2000-6000r/min. The stirring time is usually 120 seconds. Immediately measure the density after stopping stirring. Measure again in 15 minutes. Compare with the sample before high-speed stirring.
Defoamer detection method 4:High speed mixing method, foam level measurement method: put 100ml of coating sample into a 200ml high shaped beaker with a 1ml scale, add defoamer, and then use homogenizer to stir at a constant speed of 3000~4000r/min. Time is 120-180 seconds. Determine the foam height at each point of mixing time of 30, 60, 120 and 180 seconds. Set the initial height of the sample to L-0, and for every 1ml increase, use L-1 and L-2&Hellip; L-n represents it. The mixing time can be fixed to measure the height of foam. It can also make the foam reach a certain height and observe the time required.
