Characteristics and Functions of Defoaming Agents

Defoamer, also known as antifoam agent, is essentially a substance that eliminates foam. It has a lower surface tension and higher surface activity, capable of suppressing or eliminating foam in a system. In industrial production processes, a lot of harmful foam can be generated, which severely hinders production progress. At this point, a defoamer needs to be added to eliminate these harmful foams.

Defoamers have a wide range of applications and can be used to eliminate harmful foam generated during the production processes in industries such as latex, textile sizing, coatings, petrochemicals, papermaking, industrial cleaning, and food fermentation.

Antifoaming agent characteristics

There are many types of defoamers, including oil-based, solvent-based, organic silicon-based, emulsion-based, and solid powder types. All defoamers possess the following properties:

1. Strong defoaming ability, low dosage;

The addition of the defoamer will not affect the basic properties of the system.

3. Low surface tension;

Good surface balance.

5. Good dispersion and permeability;

6. Good heat resistance and acid-alkali resistance.

Chemical stability with strong oxidation resistance.

8、气体溶解性、透过性好；

9. Low solubility in foaming solution;

High physiological safety.

The role of defoamers.

Antifoaming agents possess the ability to defoam or suppress foam because they have very low surface tension, which allows them to penetrate and disrupt the bubble film, resulting in a defoaming effect. When antifoaming agents are added to the foaming medium, they settle on the surface of the bubbles and effectively reduce the surface tension at the point of contact, creating a weak spot on the bubble’s outer skin, thereby causing the bubble to burst.

According to the functions of defoamers, they can be divided into three types: foam breakers, foam inhibitors, and deaerators. Foam breakers are substances added after a liquid foams; they work by adsorbing onto the foam and, through the action of surface tension, enter the foam film to thin the base, quickly destroying bubbles and lowering the liquid surface. Foam inhibitors are substances that can prevent foam formation; they adsorb onto the bubble along with the foaming substance, reducing surface tension, thinning the foam film, and leading to rupture, thus preventing foam formation. Deaerators adsorb onto bubbles in the liquid, gathering air within the bubbles. After the bubbles adhere to each other, they rupture at the adsorption interface to form a large bubble, which, due to increased buoyancy, rises more quickly and promotes deaeration. Generally, defoamers possess multiple functions, including breaking, inhibiting, and deaerating foam.