Hydrophobicity and fermentation process of polyether defoamer
Polyether modified silicone defoamer is easily emulsified in water, also known as “self-emulsifying defoamer”. When the temperature is above its turbidity point, it loses its solubility and mechanical stability in water, and is resistant to acids, alkalis and inorganic salts. It can be used for defoaming under harsh conditions and is widely used in high-temperature dyeing and fermentation processes of polyester fabrics.
In addition, it can also be used for defoaming in diethanolamine desulfurization systems and various oils, cutting fluids, antifreeze, water-based inks and other systems. It is also suitable for defoaming after photosensitive resin platemaking in the printing industry, and washing away uncured resin. It is a very representative, excellent and widely used silicone defoamer. Polyether defoamers are usually composed of two main components, polydimethylsiloxane and silicon dioxide, which are appropriately combined. Defoamers based on polydimethylsiloxane are an ideal defoamer in the defoaming system because they are insoluble in water and difficult to emulsify. Polydimethylsiloxane has lower surface properties than carbon chain hydrocarbons, so it has lower surface tension than surfactants commonly used in the textile industry.
Pure polydimethylsiloxane has poor and slow antifoaming performance, and the defoaming effect needs to be enhanced by silica particles. The silica particles are brought to the air-water interface of the foam by silicone oil and enter the bubble liquid film. Due to its hydrophobicity, the contact angle with the surfactant foaming droplets is greater than 90°, thereby forcing the foaming liquid to be discharged from the surface of the solid hydrophobic particles. Pure polydimethylsiloxane has poor and slow antifoaming performance, and the defoaming effect needs to be enhanced by silica particles. The silica particles are brought to the air-water interface of the foam by silicone oil and enter the bubble liquid film. Due to its hydrophobicity, the contact angle with the surfactant foaming droplets is greater than 90°, thereby forcing the foaming liquid to be discharged from the surface of the solid hydrophobic particles, causing the local rapid drainage of the foam and leading to rupture. In this way, due to the synergistic effect, the two components produce a good defoaming effect.
