Lebanon What are the Free of silicone defoamers for paints(1)

foam

Lebanon Selection of antifoaming agents for different applications:

There is no unified understanding of the mechanism of defoaming agents. According to the mechanism of defoaming agents proposed by predecessors, there are generally the following types: [4]
General defoaming mechanism
Typical defoaming mechanisms with a broad overview are the Robinson defoaming mechanism and the Ross hypothesis. Among them, Robinson mechanism is the basis of Ross hypothesis, which mainly emphasizes the liquid drainage of defoamer destroying foam and Marangoni effect to realize defoaming; The Ross hypothesis is based on the fact that the defoamer particles are insoluble droplets, while some defoamers actually produce defoaming effects in a dissolved state, so the defoaming mechanism of the Ross hypothesis is not comprehensive

Flat coating

leveling

Features: Low viscosity, low defoaming pressure

Recommendation: Mineral oils or mineral oil modified polyethers

Elastic coating

Features: High viscosity, high Free of silicone defoamers pressure

Alkyl modified organosiloxane
As mentioned earlier, polyether modified polysiloxanes have some shortcomings; Alkyl modified polysiloxanes have precisely these advantages.
This series of polysiloxane products also belong to the comb structure. The molecular weight of this type of product is relatively small, around 10000, and n+m is about 30-50. The main purpose of modifying with alkyl is to improve thermal stability, compatibility, and unstable foaming, and even to have defoaming functions. However, as the modified alkyl chain increases, its ability to reduce surface tension also decreases

Recommendation: Polyether modified silicone

Surface coating and film covering adhesive

Recommendation: Polyethers, which can effectively prevent surface defects and have a small impact on gloss

Water in Water Colorful

Features: More surfactants, stable foam

unstable

Lebanon Recommendation: Use polyethers or mineral oil to modify polyethers

There are many types of leveling agents, and the types of leveling agents used for different coatings are also different. High boiling solvent or butyl cellulose can be used in solvent based finishing agents. Surfactants or polyacrylic acid, carboxymethyl cellulose, etc. are used in water-based finishing agents.

Precautions for use of paint Free of silicone defoamers:

Before use, stir thoroughly and mix evenly; Adding the paint while stirring; Before use, it is generally not diluted with water; The dosage should be appropriate. Excessive dosage can cause shrinkage, edge shrinkage, poor brushing performance, and other problems; Too little dosage leads to poor defoaming effect; Add it in two stages, namely, add it in the grinding stage and the paint mixing stage, generally accounting for half of the total amount each time. Use defoaming agents with good foam suppression effect in the grinding stage, and use defoaming agents with good foam breaking effect in the paint mixing stage