Briefly describe the three types of leather specific defoamers

Defoamers are a common chemical additive, and since many industries require the use of defoamers in industrial production, there are generally many types of defoamers available. The defoamers used in the paint industry are non-ionic surfactants, and based on their chemical composition, defoamers used in leather can be mainly divided into the following three types:

1. Organic silicon.This type is the most commonly used and primary defoamer, as discussed earlier. 

2. Mineral oils.This type of defoamer is generally composed of about 80% carrier oil, about 15% hydrophobic particles, and about 5% emulsifiers, preservatives, and other enhancing ingredients. Carrier oil is a mineral oil of aliphatic or aromatic origin. Aromatic mineral oils can easily cause yellowing of paint films and contain a large amount of aromatic hydrocarbons, which can cause physiological harm. Therefore, waterproof defoamers have better performance than aliphatic ones. Hydrophobic particles are generally made of hydrophobic gas-phase silica, stearic acid salts, fatty acid derivatives, or polyurea compounds. The function of emulsifiers is to disperse hydrophobic particles in the carrier oil, while also having a positive effect on the mixing of defoamers into coatings. This type of defoamer is mainly used in flat and semi gloss latex paints. 

3. Does not contain silicone polymers.This is a special type of polymer that functions through selected immiscibility. In order to achieve a balance between "miscibility" and "immiscibility", it is necessary to consciously change the polarity and relative molecular weight (including relative molecular weight distribution) of the polymer. Generally, the larger the relative molecular weight, the less miscible it is. But for polymer defoamer, even though its compatibility is too good, resulting in weak defoaming effect or even no defoaming effect, it will not stabilize foam, which is the biggest difference between it and silicone defoamer.