Do you know the major applications of silicone defoamers?

1. Textile printing and dyeing:

• Sizing process: water emulsion type silicone defoamer, such as: silicone polyether, the amount added in the sizing tank is 0.2¬0.25g / L
• Chemical fiber oil agent: chemical fiber oil agent is added with 0.02¬0.04% water emulsion defoamer. The chemical fiber oil formulation should contain silicone oil.
• Desizing and refining: use polyether-containing silicone.
• Bleaching: Strong acidity, silicone defoamer.
• Dyeing: Silicone emulsion defoamer. It is best to use polyether silicone for jet dyeing, which is high-temperature defoaming, low-temperature water-soluble, and does not stain the fabric.

2. Petrochemical industry:

1. Drilling: ethyl silicone oil (or methyl silicone oil layer emulsion) is used for mud additives.
2. Oil recovery: oil and gas separation, defoaming stick. The melting point is 2.8 13.9 ° C higher than the foam temperature at the wellhead.
3. Absorption of natural gasoline: Dimethyl silicone oil is mixed into 2% solution with gasoline.
4. Oil and gas separation and demulsification:
   • Oil and gas separation, adding 0.025 ～0065mg / Kg to crude oil can improve production capacity;
   • Demulsification: The crude oil separated from oil and gas is generally a micro-W / O type emulsion. Adding about 0.2mg / Kg of suitable defoaming agent can achieve the effect of demulsification and defoaming.
5. Refining: defoaming agent is added under vacuum distillation, the color of the distillate is improved, and the range of the distillate is widened. Diesel solution with silicone oil is commonly used.
6. High-energy fuel (internal combustion, jet, aviation fuel) is dispersed in high flash point kerosene with cyanoalkyl polysiloxane, and then added to high-energy fuel as an efficient defoamer.
7. Asphalt and residual oil: the amount of added silicone oil is 0.2 × 10-6 ～0 × 10-6
8. Delayed coking, decoking, descaling: reference amount of defoamer added: 0.05 ～ 100 × 10－6
9. Defoaming drilling fluid: high-viscosity sulfometallic salt (petroleum sulfonate calcium: sodium sulfonated pitch = 1: 1), the addition of siloxane is about 100 ～ 400 × 10－6 or 5 ～ 15mg / Kg Sulfonate: siloxane is close to 1: 1.
10. Lubricating oil: such as internal combustion engines, automotive lubricants, metal working fluids, compressor oils, etc., when silicone oil is used for defoaming, it is because of the following advantages:

• It is difficult to dissolve in lubricating oil and is in a dispersed state, which is conducive to adsorbing on the bubble film to break the bubble;
• There are alkyl groups similar to mineral oil, which can be squeezed into the bubble film and weaken the molecular attraction;
• Low surface tension, good penetration, when adsorbed on the surface of the bubble film, the local surface tension is reduced, and the bubble is broken due to the uneven surface tension of the bubble film. For heavy oil, use silicone oil with low viscosity, and add 1 ～ 10 × 10-6. In addition, alkyl polyacrylates are also better and have better gas release properties. Branched-chain amine is added to crude gasoline and naphtha, and then added to lubricating oil. It can also be used as an anti-foaming agent. The added amount is slightly 0.05-1%. This anti-foaming agent can be added to metal cutting fluid.

3. Paper industry

• Pulp: Silicone emulsion defoamer (90g / T paper).
• Coated paper: coated paint, paper for printing pictorials after calendering, and non-silicone defoamer for coating air bubbles.
• Sewage treatment: water emulsion type silicone defoamer.

4. Paint and Coating

I. Requirements for defoamers in paint production:

1. It has a certain affinity with the active material on the surface of the foam, but it should be insoluble and insoluble in the 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. After the coating film is formed, it cannot cause the undesirable consequences of fisheyes and shrinkage cavities;
5. Antifoaming agent for water-based coatings: Insoluble substances in water are mostly used, such as mineral oil, higher alcohol, and silicone resin. Silicone is the best antifoaming agent for water-based coatings.

Defoamer 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, excessive amount is easy to shrink and crater, and now modified silicone resin is mostly used Or emulsified silicone resin)

II. Silicone defoamer recommended for water-based coatings:

1. Silicone oil, hydrophobic SiO2 mixture is suitable for: epoxy resin, casting, 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, the amount of dip coating is 0.3%, and the amount of blade coating is 0.1%
3. The mixture of hydrophobic SiO2, hydrocarbons, and silicone oil is suitable for: thermoplastic acrylic resin, printing, ink, dosage 0.1%; air-drying acrylic resin, pouring coating, dosage 0.5%.
4. Silicone oil and hydrophobic SiO2 mixture emulsion is suitable for: Alkyd modified styrene-acrylic resin, cast, dosage 0.5%

5. Silicone defoamer for detergent industry

Polysiloxane and modified sodium tripolyphosphate are used as powdered detergent additives. The emulsion containing dimethyl silicone oil (1500c.s) containing 2-6% of SiO2 is mixed with anhydrous sodium tripolyphosphate. The amount of emulsion is 10-40 %, Forming hydrates as additives.

Metal cleaning fluids require alkali resistance. When liquids are added, they are transparent and have defoaming activity.

6. Organic silicon defoamer for food industry

Food-specific polysiloxane resin: dimethyl polysiloxane as the main body, when the food containing 15% or less of SiO2 is an aqueous solution, the emulsified product can be used, and other oil-based products can be used directly. The amount is controlled.

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