Do you know all the three major defoaming agents used in coatings?

Defoaming agent

1. Polyether defoaming agent

It has strong anti-foaming and foam-suppressing capabilities, with a small dosage and does not affect the basic properties of the bubble system. 2. It has good heat resistance, chemical stability, non-corrosive, non-toxic, no adverse effects, non-flammable and non-explosive. 3. Compared with imported products, the performance is not much different, and the price is more advantageous.

2. Silicone defoamer

It is superior to the special chemical molecular structure of silicone oil, so it has a relatively wide range of applications. It can be used in both water-based and oil-based systems. 2. Small surface tension and good stability. It has good chemical stability and is difficult to react chemically with other substances. 3. It has strong defoaming ability, which can not only effectively break the foam that has been generated, but also significantly inhibit the foam and prevent the formation of foam.

3. Mineral oil defoamer

It has the characteristics of rapid defoaming, high efficiency, long-lasting defoaming and good economy. 2. Can be dispersed in water to form an emulsion with moderate stability. 3. Can be used under both acidic and alkaline conditions.

Depending on the construction conditions (such as brushing, spraying, dipping, printing, etc.), different testing methods can be selected. Finally, the editor shares some practical tests on defoaming agents. Stirring test For us users, the simplest test method is the stirring test. Under certain conditions, a turbine blade is used to infiltrate air into the coating system to be tested with a defoaming agent.

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After stirring, immediately pour the material into a measuring bottle with a marked scale, and then weigh it. By comparing the weight difference, the amount of air infiltrated into the system can be determined, thereby inferring the effect of the defoamer. This test also shows how much air is present in the system in the form of spherical bubbles. Another test method is used to detect the number of macrobubbles. Under certain conditions, air is infiltrated into the system, and then the height of the material with the same weight is measured using a graduated cylinder to evaluate the effect of the defoaming agent. This method can guide us in selecting the capacity ratio of the mixing container in actual work. Many defoaming agents can also cause paint film surface defects, such as shrinkage holes, etc., which is the same as the foam problem. It is something that all our ink producers do not want to see. This can only be achieved through mass and wide application before batch use. Conduct experiments and trials.

Flow coating test The flow coating test can be used to evaluate the compatibility and defoaming effect of the defoaming agent with the tested coating system. Immediately pour the stirred test specimen onto a piece of polyester film.The polyester film must be placed on a vertical frame with an inclination of 25 degrees in advance. Observe the flow-coated test piece carefully to see if there are any bubbles introduced on it. This method can also evaluate the defoaming effect of the defoaming agent by observing the dry film. In some cases, the defoaming agent selected through the stirring test and flow coating test and the amount of addition are not enough to explain the problem and evaluate the substrates whose surface is not very smooth and contains air. When determining the optimal amount of defoamer, the final use of the product should be fully considered.

Roller coating test The method of roller coating test is very close to the actual construction conditions of the coating, so that the effects of different defoaming agents can be distinguished. You can even experiment with the amount added.