Defoamer manufacturer Here’s the mechanism of action of silicone-based defoamers.

　　The defoaming or foam‑suppressing capability of organosilicon compounds stems from their exceptionally low surface tension. Organosilicon substances (silicone oils) disrupt the surface tension at the gas–liquid interface, thereby achieving a defoaming effect.

　　When silicone is added to a foam medium, the fine particles of silicone oil settle on the bubble surface, effectively reducing the surface tension at the contact points and creating a weak spot in the bubble wall, thereby inducing bubble rupture.

　　The optimal criteria for defoaming activity can be summarized as follows: free silicone oil droplets must be dispersed throughout the active zone completely, as rapidly as possible, and with maximum efficiency. By leveraging the addition of a small‑amount, high‑surface‑area SiO₂ filler during manufacturing, the silicone oil is swiftly dispersed and, at the points where it contacts the SiO₂ particles, induces emulsion and foam breakdown. The closely packed bubbles, destabilized by the rupture of neighboring bubbles, accelerate the cascade of continuous defoaming until a stable state is ultimately achieved. In the case of emulsion‑based defoamers, excessive emulsion stability diminishes defoaming performance, whereas poor stability confers greater activity. Consequently, a balance between stability and activity must be struck, and organosilicon compounds with low solubility in both the aqueous and oily phases—yet exhibiting exceptionally high activity—should be selected.

　　The functions of defoamers are also classified according to three mechanisms: foam-breaking, foam-removal, and foam-inhibition.

　　Bubble rupture: Relative to the bubble, it enters from the air side and coalesces with the bubble, thereby destroying it.

　　Defoaming: Bubbles are introduced from the liquid side, where they are coalesced and destroyed.

　　Defoaming: It penetrates the bubble interface, causing bubbles to coalesce and rise to the liquid surface.

　　 Applications of Silicone Defoamers

　　1

　　(1) Sizing process: Use an aqueous emulsion‑type silicone defoamer, such as BD‑304 (or a silicone‑polyether), at an addition level of 0.2–0.25 g/L in the sizing bath.

　　(2) Synthetic fiber oil agent: Add a 0.02–0.04% aqueous emulsion‑type defoamer to the synthetic fiber oil agent. The formulation of the synthetic fiber oil agent should include organosilicone polyether silicone oil.

　　(3) Desizing and refining: Use a polyether‑silicone‑based formulation, such as BD‑3055.

　　(4) Bleaching: Highly acidic, silicone-based defoamer.

　　(5) Dyeing: Silicone emulsion defoamer. For jet dyeing, polyether‑silicone is preferred, offering excellent defoaming at high temperatures and water solubility at low temperatures, without staining the fabric.

　　2

　　(1) Drilling: Ethyl silicone oil (or methyl silicone oil emulsion) is used as a mud additive.

　　(2) Oil production: oil–gas separation, defoaming stick. Its melting point is 2.8–13.9°C higher than the foam temperature at the wellhead.

　　(3) Natural gasoline absorption: Prepare a 2% solution of dimethyl silicone oil using gasoline.

　　(4) Oil–gas separation and demulsification:

　　A. Oil–gas separation: Adding 0.025 to 0.0065 mg/kg to crude oil can enhance production capacity.

　　B. Demulsification: Crude oil separated from gas typically forms a weak W/O-type emulsion; adding an appropriate defoamer at approximately 0.2 mg/kg can achieve both demulsification and defoaming.

　　(5) Refining: Vacuum distillation with the addition of a defoaming agent improves the color of the fractions and broadens their boiling ranges; a common practice involves using a diesel solution containing silicone oil.

　　(6) Cyanated polysiloxanes are dispersed in high‑flash‑point kerosene for use as high‑performance antifoaming agents in high‑energy fuels (internal‑combustion, jet, and aviation fuels), and then added to the fuel.

　　(7) Asphalt and residual oil: The amount of silicone oil added is 0.2 × 10⁻⁶ to 2.0 × 10⁻⁶.

　　(8) Delayed coking, coke removal, and scale inhibition: Recommended dosage of defoamer: 0.05–100 × 10⁻⁶

　　(9) Defoaming drilling fluid: high-viscosity sulfonated metal salts (calcium petroleum sulfonate:sodium sulfonated asphalt = 1:1), with a siloxane addition of approximately 100–400 × 10⁻⁶ or 5–15 mg/kg; a molar ratio of sulfonate to siloxane close to 1:1 is preferred.

　　(10) Lubricants: such as internal‑combustion engine oils, automotive lubricants, metalworking fluids, and compressor oils. When silicone oil is added as an antifoaming agent, it offers the following advantages:

　　A. Poorly soluble in lubricating oil and exists in a dispersed state, which facilitates its adsorption onto the bubble film to promote bubble rupture.

　　B. It contains alkyl groups similar to those in mineral oil, which can penetrate the bubble film and weaken intermolecular forces;

　　C. It has low surface tension and excellent penetration; when adsorbed onto the bubble film, it reduces the local surface tension, leading to bubble rupture due to uneven surface tension across the film.

　　For heavy oils, low-viscosity silicone oils are preferred, with an addition level of 1 to 10 × 10⁻⁶. In addition, alkyl polyacrylates are also advantageous, offering excellent gas‑release properties.

　　Branched-chain amines can be added to crude gasoline and naphtha, and subsequently incorporated into lubricating oils; they also serve as defoaming agents. The typical dosage is 0.05–1% by weight, and this defoamer can be formulated into metalworking fluids.

　　3

　　(1) Pulping: Silicone emulsion defoamer (90 g/ton of paper).

　　(2) Coated paper: A type of paper coated with a coating formulation and calendered, used for printing posters and other applications; non-silicone defoamers are typically employed to control foam during the coating process.

　　(3) Wastewater treatment: Water‑emulsion‑type silicone defoamers, such as the BD‑303 silicone defoamer.

　　4

　　I. Requirements for defoamers in paint production:

　　(1) It exhibits a certain affinity for the surfactants on the foam surface, but should be poorly soluble or insoluble in the bubble‑forming liquid.

　　(2) It has a surface tension lower than that of the bubble liquid and a relatively low HLB value;

　　(3) The emulsion (latex) should be stabilized;

　　(4) After film formation, the coating must not cause undesirable defects such as fish eyes or craters.

　　(5) Defoamers for waterborne coatings: These typically employ substances that are poorly soluble in water, such as mineral oil, higher alcohols, and organosilicon resins; among them, organosilicon compounds are the most effective defoamers for waterborne coatings.

　　Defoamers for non-aqueous coatings: Commonly used are substances that are poorly soluble in organic solvents, such as lower alcohols and organosilicon resins (the dosage of organosilicon resin should be moderate; excessive amounts can lead to cracking and pinholing. Nowadays, modified organosilicon resins or emulsified organosilicon resins are more widely employed).

　　II. Recommended silicone-based defoamers for waterborne coatings:

　　(1) Silicone oil–hydrophobic SiO2 blend: suitable for epoxy resins, applied by potting at 0.3%; thermoplastic acrylic resins, applied by spraying at 0.3%.

　　(2) Polyether–polysiloxane/silica hybrid: suitable for thermosetting alkyd resins; application rate of 0.3% for dip coating and 0.1% for blade coating.

　　(3) A mixture of hydrophobic SiO2, hydrocarbons, and silicone oil is suitable for thermoplastic acrylic resins and printing inks, at a dosage of 0.1%; for air-drying acrylic resins used in casting, the dosage is 0.5%.

　　(4) Emulsion of silicone oil and hydrophobic SiO2: suitable for alkyd-modified styrene–acrylic resin; applied by pouring, at a dosage of 0.5%.

　　5

　　Polysiloxanes and modified sodium tripolyphosphate are used as additives in powdered detergents. A dimethylsilicone oil (1500 cSt) emulsion containing 2–6% SiO₂ is blended with anhydrous sodium tripolyphosphate, with the emulsion accounting for 10–40% of the formulation, to produce a hydrated compound serving as an additive.

　　Metal cleaning solution, requiring alkali resistance; ideally, it should remain clear and exhibit defoaming activity when liquid additives are incorporated.

　　6

　　Food-grade polysiloxane resin: Primarily composed of dimethylpolysiloxane, with less than 15% SiO2. When used in aqueous solutions, emulsified products are recommended; otherwise, oil-based formulations may be applied directly. Dosage should be kept below 0.05 g/kg. Typical applications include fermentation and sugar production. Silicone–ethylene glycol copolymers are particularly suitable for foam suppression during fermentation.

　　Conclusion: Although the foam generated in industrial production is fine, its impact can be significant. Selecting an appropriate defoamer can effectively mitigate foam’s adverse effects on manufacturing, enhance production efficiency, and ensure product quality. With ongoing industry advancements and technological progress, the development and application of silicone‑based defoamers will increasingly permeate diverse industrial and chemical manufacturing sectors.