6 major applications of silicone defoamer
1. Textile printing and dyeing:
(1) Sizing process: water-emulsion type silicone defoamer, such as silicone polyether, the amount added in the sizing tank is 0.2¬0.25g/L
(2) Chemical fiber oil agent: Add 0.02¬0.04% water emulsion defoaming agent to the chemical fiber oil agent. The chemical fiber oil formula should contain silicone oil.
(3) Desizing and refining: Use polyether-containing silicone.
(4) Bleaching: Strong acidity, silicone defoaming agent.
(5) Dyeing: silicone emulsion defoaming agent. It is best to use polyether silicone for jet dyeing, which is defoaming at high temperatures, water-soluble at low temperatures, and does not stain fabrics.
2. Petrochemical industry:
(1) Drilling: Ethyl silicone oil (or methyl silicone oil layer emulsion) is used as a mud additive.
(2) Oil recovery: oil and gas separation, defoaming rod. The melting point is 2.8-13.9℃ higher than the wellhead foam temperature.
(3) Natural gasoline absorption: Use gasoline to prepare a 2% solution of dimethyl silicone.
(4) Oil and gas separation and demulsification:
A. Oil and gas separation, adding 0.025~0.0065mg/Kg to crude oil can improve production capacity;
B. Demulsification: Crude oil separated from oil and gas is generally a micro-W/O emulsion. Adding a suitable defoaming agent of about 0.2mg/Kg can achieve the effect of demulsification and defoaming.
(5) Refining: Defoaming agent is added to vacuum distillation to improve the color of the fraction and broaden the range of the fraction. Diesel solutions containing silicone oil are commonly used.
(6) For high-energy fuel (internal combustion, jet, aviation fuel), cyanoalkyl polysiloxane is dispersed in high-flash point kerosene, and then added to the high-energy fuel as an efficient defoaming agent.
(7) Asphalt and residual oil: The amount of silicone oil added is 0.2×10-6~2.0×10-6
(8) Delayed coking, decoking, and descaling: Defoaming agent addition reference amount: 0.05~100×10-6
(9) Defoaming drilling fluid: high viscosity sulfonate metal salt (petroleum calcium sulfonate: sodium sulfonated asphalt = 1:1), the amount of siloxane added is about 100~400×10-6 or 5~15mg/Kg, Sulfonate:siloxane is preferably close to 1:1.
(10) Lubricating oils: such as internal combustion engines, automotive lubricants, metal working fluids, compressor oils, etc., when silicone oil is added for defoaming, the following advantages occur:
A. It is difficult to dissolve in lubricating oil and is in a dispersed state, which is conducive to adsorption on the bubble film and breaking the bubbles;
B. It has an alkyl group similar to mineral oil, which can squeeze into the bubble membrane and weaken the molecular gravity;
C. Low surface tension and good penetration. When adsorbed on the surface of the bubble film, the local surface tension is reduced, and the bubbles are broken due to uneven surface tension of the bubble film. For heavy oil, choose silicone oil with small viscosity, and add the amount of 1 to 10×10-6. In addition, alkyl polyacrylates are also better and have better gas release properties. Branched-chain amines are added to crude gasoline and naphtha, and then added to lubricating oil. They can also be used as defoaming agents in an amount of 0.05 to 1%. This defoaming agent can be added to metal cutting fluids.
3. Paper industry
(1) Pulping: Silicone emulsion defoaming agent (90g/T paper).
(2) Coated paper: Paper used for coating coatings, calendering and printing pictorials, etc. Non-silicon defoaming agents are generally used to coat bubbles.
(3) Sewage treatment: water emulsion type silicone defoamer.
4. Application in coatings and inks
I. Requirements for defoaming agents in coating production:
(1) It has a certain affinity with the active substances on the foam surface, but it should be insoluble and insoluble in the re-bubble liquid;
(2) The surface tension is lower than that of the bubble liquid and has a lower HLB value;
(3) The emulsion (latex) should be stabilized;
(4) The coating must not cause fish eyes or shrinkage cavities after film formation;
(5) Defoaming agent for water-based coatings: Use more insoluble substances in water, such as mineral oil, higher alcohols, and silicone resins. Silicone is the best defoaming agent for water-based coatings.
Defoaming agent for non-aqueous coatings: commonly used substances that are difficult to dissolve in organic solvents, such as lower alcohols and silicone resins (the amount of silicone resin should be appropriate, as excessive amounts may cause shrinkage, cracking, and cavitation. Nowadays, modified silicone resins are often used. or emulsified silicone resin)
II. Recommended silicone defoamer for water-based coatings:
(1) Silicone oil and hydrophobic SiO2 mixture is suitable for: epoxy resin, pouring, dosage 0.3%; thermoplastic acrylic resin, spraying, dosage 0.3%
(2) The mixture of polyether polysiloxane and hydrophobic SiO2 is suitable for: thermosetting alkyd resin, dipping dosage 0.3%, scraping dosage 0.1%
(3) The mixture of hydrophobic SiO2, hydrocarbons and silicone oil is suitable for: thermoplastic acrylic resin, printing and ink, dosage 0.1%; air-drying acrylic resin, pouring, dosage 0.5%.
(4) Silicone oil and hydrophobic SiO2 mixture emulsion is suitable for: alkyd modified styrene acrylic resin, pouring, dosage 0.5%
5. Silicone defoamer for detergent industry
Polysiloxane and modified sodium tripolyphosphate are used as powdery detergent additives. Dimethyl silicone oil (1500c.s) emulsion containing 2 to 6% SiO2 is mixed with anhydrous sodium tripolyphosphate. The dosage of the emulsion is 10 to 40 %, forming hydrate as additive.
Metal cleaning fluid requires alkali resistance. It is best to add liquid products that are transparent and have defoaming activity.
6. Silicone defoamer for food industry
Food-specific polysiloxane resin: dimethyl polysiloxane is the main body and contains less than 15% SiO2. When the food is an aqueous solution, use its emulsified product. Others can directly use oil-type products, and the dosage is controlled.
