What are the types of silicone defoamer?
Conventional silicone defoamer is divided into four categories according to its physical properties: silicone oil type, silicone oil solution type, silicone oil mixture type and silicone oil emulsion type. It is also commonly used in the market of defoamer at present.
Silicone oil defoaming agent has better antifoaming performance, the key is the emulsion of silicone oil. If the emulsification is not complete, there will be demulsification in use, which will affect its antifoaming effect. Commonly used silicone defoaming agents are silicone oil as the base component, with appropriate solvents, emulsifiers or inorganic fillers prepared.
After emulsifying the silicone oil, the surface tension is rapidly reduced, so it is easy to adsorb on the surface of the foam liquid and spread on the liquid surface. The formed surface film has small viscosity and low strength, so it can cause the local surface tension imbalance on the foam, so that the liquid film is thinner and broken, so as to achieve the purpose of defoaming. At the same time, it also has the effect of anti-bubble. In addition, emulsion antifoaming agent has a greater affinity for water, a wide range of pH values to adapt to, no adverse effect on sizing, will not produce stains on paper. And the use of a very small amount of that can achieve strong foaming and anti-foaming effect, so it becomes an important antifoaming agent component.
According to the hydrophilic oil-wet equilibrium value H (LB) choose non-ionic surfactant as compound emulsifier, in the water phase and organic silicon compound with: in organic silicon content is 20% ~ 25%, the composite emulsifier (emulsifier to give attention to two or morethings arrives the activity and emulsion stability of organic silicon) content at 3% ~ 5%, compound effect is better when temperature is 60 ~ 80 ℃. Compound silicone emulsion defoaming agent has good defoaming effect and stability, environmental protection, no pollution, low cost, wide application range, has a great development prospect.
Modified silicone polyether defoamer, which is a new type of defoaming agent combining the advantages of silicone and polyether antifoaming agent. The antifoaming agent has strong anti-foaming ability of polyether and hydrophobicity, rapid foaming dimethyl silicone oil as the main components and can make silicone oil and polyether organic combination of emulsifier, stabilizer and other components of the defoamer agent. Defoaming agent has the characteristics of low surface tension, rapid antifoaming, lasting antifoaming, low price and wide application. It is a new kind of popular antifoam at present.
