Dimethyl silicone oil defoamer is composed of core active ingredients, auxiliary synergistic ingredients and carrier/emulsification system. The formulations vary slightly among different types including oil-based, emulsion and powder types, while the core structure remains consistent.
Core Active Ingredients (Main defoaming components, accounting for 10%–50%)
Polydimethylsiloxane (PDMS), commonly known as dimethyl silicone oil
It acts as the key defoaming component, providing extremely low surface tension (20–21 mN/m) for fast bubble breaking and long-lasting foam inhibition. It is chemically inert, resistant to high and low temperatures (-50°C ~ 200°C), hydrophobic and insoluble in most systems. The common viscosity ranges from 100 to 10000 cSt. Low-viscosity grades deliver fast defoaming, while high-viscosity grades provide longer foam control.
Hydrophobically modified silica (white carbon black)
It supports defoaming and strengthens foam inhibition, improves the spreading performance of silicone oil and extends the service life of the defoamer. It is hydrophobically modified with silanizing agents such as hexamethyldisilazane to prevent agglomeration, with a typical dosage of 2%–8%.
Optional: MQ silicone resin / polyether modified silicone oil
It improves the stability and compatibility of the defoamer, and enhances long-lasting foam inhibition.
Auxiliary Ingredients (Synergistic and stabilizing components, accounting for 5%–30%)
Emulsifier: Disperses silicone oil into fine particles to suit aqueous or oil-based systems.
Carrier / Solvent: Reduces viscosity and aids dispersion.
Dispersant: Prevents particle agglomeration.
Stabilizer: Improves storage stability.
Preservative: Inhibits microbial growth, mainly used in emulsion-type products.
Carrier / Dilution System
Oil-based type: Formulated with mineral oil/liquid paraffin, silicone oil and hydrophobic silica.
Emulsion type: Formulated with deionized water, silicone oil, emulsifier and stabilizer.
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