Ghana What are the paint defoamer for paints(1)

Ghana Selection of antifoaming agents for different applications:

Stability factors of foam
The direct cause of foam is the presence of surfactant, which reduces the surface tension of the solution. Under the combined effect of this reason and the attenuation mechanism of foam, different foam systems show different stability properties, which are mainly related to the following factors: the surface tension of foaming solution, the surface viscosity of foam, the viscosity of solution, the self-healing effect of surface tension (i.e. Gibbs surface elasticity and Marangoni effect) "The surface double layer repulsion and entropy repulsion forces of liquid membranes, the hydrophobic end structure of surfactants, and the steric hindrance effect are not independent factors, and changes in one factor can cause other factors to also change.". The most important factors affecting the stability of foam are the elasticity of the liquid film and the liquid discharge rate. From this perspective, it can be seen that the main factors affecting the stability of foam are different in different foam systems, and sometimes several factors exist at the same time and work together.
In addition to the above factors, some other factors will also affect the stability of foam, such as the size of foam, the coordination of solute and solvent, temperature, pH value, the evaporation rate of solvent, the impact degree of foam and the adsorption rate of surfactant

Flat coating

Features: Low viscosity, low defoaming pressure

leveling

Recommendation: Mineral oils or mineral oil modified polyethers

Elastic coating

anti-oil

Features: High viscosity, high paint defoamer pressure

The chemical methods to eliminate foam mainly include chemical reaction method and adding defoamer. The chemical reaction method refers to the chemical reaction between the foaming agent and the foaming agent by adding some reagents to generate water insoluble substances, thus reducing the concentration of surfactant in the liquid film and promoting the rupture of foam. However, this method has some shortcomings, such as the uncertainty of foaming agent composition and the harm of insoluble substances to system equipment. Nowadays, the most widely used defoaming method in various industries is the method of adding defoaming agents. The greatest advantages of this method are high foam breaking efficiency and convenient use, but finding suitable and efficient defoaming agents is the key.

agent

Recommendation: Polyether modified silicone

Surface coating and film covering adhesive

Explanation in reference book
An agent that promotes the uniform dispersion of material particles in the medium to form a stable suspension. Dispersants are generally divided into two categories: inorganic dispersants and organic dispersants. Commonly used inorganic dispersants include silicates (such as water glass) and alkali metal phosphates (such as sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate). Organic dispersants include triethylhexyl phosphoric acid, sodium dodecyl sulfate, methyl pentanol, cellulose derivatives, polyacrylamide, gum, fatty acid polyethylene glycol esters, etc.

agent

coupling

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

metal

Water in Water Colorful

Features: More surfactants, stable foam

Ghana Recommendation: Use polyethers or mineral oil to modify polyethers

Precautions for use of paint paint defoamer:

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