In daily life and industrial processes, everyone is always more or less troubled by the foam problem. At this time, it is especially important to choose a suitable defoamer. Antifoam agent is mainly used to remove air bubbles on the surface of the liquid, in many industrial processes and demanding applications (even food processing), antifoam agent is widely used in a variety of aqueous systems to improve productivity. So why silicone defoamers are preferred?
Silicone defoamer is one of the most commonly used defoamers, and its main component is methyl silicone oil or Polysiloxane. They are capable of dispersing air bubbles in liquids and control foam effectively. Silicone defoamers have excellent defoaming performance and stability and are suitable for many industrial fields (such as metalworking fluids).
Silicone-based defoamers can quickly diffuse to the surface of the liquid, and interact with the bubbles to destroy the foam structure, to achieve a rapid defoaming effect; Silicone defoamer still maintains good defoaming performance at high or low temperatures, and has good temperature stability; Silicone defoamer has good resistance to acids, alkalis, salts, and other chemicals, and is not easy to be decomposed or inactive; Generally speaking, silicone defoamer has no obvious toxic effect on human body and environment.
Here’s some information about it:
- Why does foam arise?
- What is silicone defoamer?
- What are the types of silicone defoamers?
- What are the features of silicone defoamer?
- Why use silicone defoamer?
- How about silicone defoamer compared with inorganic silicone defoamer?
- How to apply silicone defoamer?
- How to make silicone defoamer better?
1. Why does foam arise?
When we are in production, stirring the liquid or gas mixed in, the surface area of the liquid inside will generate a lot of bubbles, some bubbles are easy to dissipate, and some bubbles are very tricky, not only do not dissipate but also more and more will be gathered to form foam. There is a medium that causes foaming such as surfactants.
2. What is silicone defoamer?
The principle of an antifoam agent is mainly through the dissolution of surface tension to reduce the droplet surface tension, so that the droplet surface energy in the liquid is reduced, and the bubble rupture. It is mainly used to eliminate foam caused by high surface tension of liquid, slurry, emulsion, oil-water separation, and other processes of foaming, also used to eliminate foam in the system of coating, ink, and paint.
Antifoaming agents are defoamers derived from silicone compounds and are mainly used to control and eliminate foaming in polymer solutions, emulsions, or suspensions. Silicone defoamers can be used in most industries, especially in chemical and industrial applications such as textile printing and dyeing, paints and coatings, and rubber tires. It has a strong defoaming ability for most organic compounds and is not easily washed out.
XJY -8205 Methyl Silicone MQ Resin, a solid powder resin with excellent transfer and water resistance and long-lasting molding, can be used to prepare high-temperature and strong alkali-resistant silicone defoamers. Adding high-viscosity hydroxyl silicone oil and silicone MQ resin to synthesize a reticulated polymer with a high degree of branching, which improves the defoamer's resistance to high temperature and strong alkali.
3. What are the types of silicone defoamers?
Silicone defoamer can be divided into five categories according to its product form: oil type, solution type, emulsion type, solid type and polyether modified, among which the emulsion-type defoamer is the most widely used and has the largest dosage.
(1) Oily silicone defoamer
This kind of antifoam agent with silicone oil as the main component, has good defoaming performance and foam inhibition performance. Silicone oil is insoluble in water, also insoluble in animal and vegetable oils and high boiling point mineral oil, so most of the foaming media have good defoaming effect.
XJY-702 Methylhydrosiloxane/Dimethylsiloxane copolymer is non-toxic and tasteless, with active genes, under the action of catalysts, it can react with double bonds, hydroxyl and other groups, and it is the basic raw material of leveling agent, antifoam agent, water-soluble silicone oil and other products.
(2) Solution-type silicone defoamer
Solution-type silicone antifoam agent is dissolved in organic solvents made of silicone oil, with high defoaming efficiency and long foam suppression time. Solution-type silicone antifoam agent is suitable for the need for rapid defoaming and the solvent requirements are not high occasions.
XJY-6010/XJY-6011/XJY-6012 Methyl MQ silicone resin for antifoam agent is a solid powder resin. This resin has good antifoaming, hydrophobic and waterproof properties, and can be used to match with the preparation of solution silicone defoamer.
(3) Emulsion-type silicone defoamer
Emulsion-type silicone antifoam agent is made of silicone oil mixed with emulsifier, with good dispersion and stability.
(4) Solid-type silicone defoamer
Solid-type silicone antifoam agent is the defoamer effective ingredients attached to the solid particles fixed in the surface of the dispersion system, while solving the problem of antifoam components and emulsifiers. Solid-type silicone antifoam agent storage stability, easy to transport, easy to use.
(5) Polyether modified silicone defoamer
Polyether modified silicone antifoam agent is through block copolymerization or graft copolymerization in the polysiloxane chain segment on the introduction of polyether chain segment, so that the polysiloxane to increase hydrophilicity, so that it has a self-emulsifying, at the same time, the introduction of the polyether chain segment as a hydrophilic group, but also reduce the polysiloxane in the oil system of affinity and solubility, the polyether modified silicone oil copolymer both the original advantages of the two types of antifoam agent, the surface tension of the polyether than the pure type of low, and more than pure siloxane, the surface tension of the polyether chain segment is lower, and more than pure siloxane, the surface tension of the polyether chain segment is lower. This polyether-modified silicone oil copolymer has the advantages of both types of defoamer, lower surface tension than pure polyether type, and better water dispersion performance than pure silicone, due to the synergistic performance of the two components, making its antifoaming and foam inhibition performance more outstanding.
4. What are the features of silicone defoamer?
(1) Silicone defoamers have a strong foam inhibition force, the dosage is small and does not affect the basic nature of the foaming system.
(2) Silicone defoamers eliminate the foam due to anionic surfactants and the viscous liquid system is particularly effective and has good alkali resistance.
(3) Silicone defoamers with high-temperature resistance, low-temperature resistance, stable physical properties, chemical inertia, and very low surface tension, is a commonly used defoamers.
5. Why use silicone defoamer?
(1) Wide range of use, silicone antifoam agents can be used in the chemical industry, paper, paint, food, textiles, pharmaceuticals, and other industrial sectors, a wide range of anti-foam, generally slightly stronger type.
(2) Dosage ratio is small, defoaming the amount of additive required is low, the proportion of additive amount is generally 0.1/% ~ 1/%. A purchase can be used for a long time, cost-effective.
(3) non-toxic and harmless, a large number of experimental data show that, although the silicone antifoam agent is a chemical additive, but non-toxic, will not affect human health, can be used safely.
Silicone antifoam agent foam inhibition performance depends mainly on the nature of the silicone oil, silicone oil content determines the use of silicone antifoam agent in the system time. The defoaming effect of silicone defoamer depends not only on its own characteristics but also on its use and dosage. For example, the particle size of the defoamer determines its filtration. If the particle size is too large or the defoamer is not stirred enough, it may cause the defoamer to be filtered out, especially in sewage treatment, which will be filtered several times. If the defoamer is filtered out, it will have an effect on defoaming and foam inhibition
Silicone defoamer, as an efficient and widely used chemical agent, plays an important role in many industrial fields due to its unique principle of action. This antifoam agent is mainly made of siloxane monomer and other additives through complex polymerization reaction and modification process, forming a polymer compound with special chemical structure.
Its core principle of action lies in the molecular structure of the silicon-oxygen group. When silicone antifoam agent is introduced into the system containing foam, these silicone oxygen groups can quickly foam in the silicon hydroxyl group of addition, condensation, and other chemical reactions. These reactions not only make the foam structure unstable but also promote the generation of stabilized siloxane polymers, thus effectively eliminating the foam and inhibiting the generation of new foam.
In addition, silicone defoamers have excellent physical properties. It can quickly diffuse to the surface of the liquid, significantly reducing the surface tension of the liquid, so that bubbles can be more easily released from the liquid. At the same time, the lipophilic groups in the antifoam agent will be adsorbed on the surface of the bubbles to form a stable film, preventing the gas from further dissolving and aggregating into new bubbles, thus realizing the double inhibition of bubble generation.
6. How about silicone defoamer compared with inorganic silicone defoamer?
Inorganic silicone defoamer is mainly composed of alumina, silicate, etc. It has good alkali resistance and heat resistance, especially in high temperature, high alkali, and high-pressure conditions with good results. Inorganic silicon antifoam agent mainly destroys the balance of bubble surface film by dispersing the foam, so as to achieve the effect of reducing the surface tension of bubbles and slowing down or eliminating the aggregation of bubbles. For a variety of oil and grease compounds, aqueous solutions chemical preparations, etc., they are widely used in industrial production. Because inorganic silicone defoamer has relatively good heat stability, it is often used in a variety of medium and high temperatures in the industrial field, such as petrochemicals, paints, inks, fertilizers, rubber, plastics, cosmetics, and so on.
In actual industrial production, silicone defoamer and inorganic silicon defoamer are widely used. According to different working conditions and needs, we can choose the corresponding defoamer for use.
Comparatively speaking, silicone-free defoamer may not be as effective as silicone defoamer in dealing with biochemical sewage foaming problem. Silicone defoamers are generally made of surfactants and other ingredients, and their defoaming effect may be affected by factors such as ions in the sewage.
7. How to apply silicone defoamer?
7.1 Textile printing and dyeing:
(1) Sizing process: water emulsion type organosilicon antifoam agent, such as organosilicon polyether, sizing tank adding amount of 0.2 ¬ 0.25g / L.
(2) Chemical fiber oiling agent: chemical fiber oiling agent to add 0.02 ¬ 0.04% water emulsion type defoamer. The chemical fiber oiling agent formula should contain silicone oil.
(3) Desizing and refining: it should choose to contain polyether silicone.
(4) Bleaching: it has strong acidity, and can choose silicone defoamer.
(5) Dyeing: silicone emulsion defoamer. Spray dyeing is best to use polyether silicone, high-temperature defoaming, low-temperature water soluble, non-staining fabrics.
7.2 Petrochemical industry:
(1) Drilling: Ethyl silicone oil (or methyl silicone oil layer emulsion) can be used for mud additives.
(2) Oil extraction: oil and gas separation, defoamer rod. The melting point is 2.8¬13.9℃ higher than the wellhead foam temperature.
(3) Natural gasoline absorption: Dimethicone is prepared as a 2% solution with gasoline.
(4) Oil and gas separation emulsion breaking:
A. Oil and gas separation: adding 0.025～0.0065mg/Kg in crude oil can increase production capacity;
B. Emulsification: oil and gas separation of crude oil is generally micro-W/O emulsion, add 0.2mg/Kg or so of the appropriate antifoam agent, can achieve the effect of emulsification and defoaming.
(5) Refining: decompression distillation adds an antifoaming agent, fraction color improvement, and fraction range relaxation, commonly used with silicone oil diesel solution.
(6) High-energy fuels (internal combustion, jet, aviation fuel) with cyanoalkyl polysiloxanes dispersed in high flash point kerosene and then added to high-energy fuels as a high-efficiency defoamer.
(7) Asphalt, residual oil: add silicone oil amount of 0.2 × 10-6 ~ 2.0 × 10-6
(8) Delayed coking, decoking, descaling: defoamer added reference amount: 0.05 ~ 100 × 10-6
(9) Defoaming drilling fluid: high viscosity sulfonate metal salt (calcium petroleum sulfonate: sodium sulfonated asphalt = 1:1), the addition of siloxane is about 100 to 400 × 10-6 or 5 to 15mg / Kg, sulfonate: siloxane close to 1:1 is preferred
(10) Lubricating oil: such as internal combustion engines, automotive lubricants, metal working fluids, compressor oils, etc., when added with silicone oil for defoaming, because of the following advantages:
A. Silicone oil is difficult to dissolve in lubricating oil, in a dispersed state, conducive to adsorption in the bubble film to break the bubble;
B. Silicone oil has a similar alkyl to mineral oil, and can be squeezed into the bubble film, weakening the molecular gravity;
C. Silicone oil has low surface tension, good penetration, and adsorption on the surface of the bubble film so that the local surface tension is reduced, due to uneven surface tension of the bubble film and bubble breaking. Heavy oil selection viscosity of small silicone oil, add 1 ~ 10 × 10-6. In addition, Alkyl polyacrylate is also better, with better gas release. Branched-chain amine added to crude gasoline, naphtha, and then added to the lubricating oil, can also be used as an antifoam agent, add the amount of micro 0.05 ~ 1%, this antifoam agent can be added to the metal cutting fluid.
7.3 Paper-making industry
(1) Pulping: the application of silicone emulsion defoamer (90g/T paper).
(2) Coated paper: coating paint, calendering, printing pictures and newspapers and other paper, coated bubbles generally use non-silicon defoamer.
(3) Sewage treatment: water emulsion type silicone defoamer.
7.4 Paint, ink
7.4.1 What are the requirements for silicone defoamers?
(1) With a certain affinity for the active substances on the surface of the foam, but then the bubble liquid should be insoluble;
(2) The surface tension is lower than the surface tension of the bubble liquid, and has a low HLB value;
(3) The emulsion (latex) should be stabilized;
(4) The coating film can not cause fish-eye and shrinkage of the adverse consequences;
(5) Antifoam agent for water-based coatings: more use of insoluble substances in water, such as mineral oil, high-grade alcohols, and silicone resin, silicone is the best antifoam agent for water-based coatings.
Non-water-based coatings with defoamer: commonly used substances insoluble in organic solvents, such as low-grade alcohols, silicone resins (silicone resin dosage should be appropriate, too much easy to shrink the cracks, traps, and now more modified silicone resins or emulsified silicone resins).
7.4.2 How to choose silicone defoamer for water-based coatings?
(1) Silicone oil, hydrophobic SiO2 mixture is applicable: epoxy resin, pouring coating, the amount of 0.3%; thermoplastic acrylic resin, spraying, the amount of 0.3%
(2) Polyether polysiloxane and hydrophobic SiO2 mixture is suitable for thermosetting alkyd resin, dip coating dosage of 0.3%, scrape coating dosage of 0.1%
(3) Hydrophobic SiO2, hydrocarbons, silicone oil mixture applies thermoplastic acrylic resin, printing, ink, the amount of 0.1%; air-drying acrylic resin, pouring coating, the amount of 0.5%.
(4) Silicone oil and hydrophobic SiO2 mixture emulsion is suitable for alkyd-modified phenylpropylene resin, pour coating, dosage 0.5%.
7.5 Detergent industry
Polysiloxane and modified sodium Tripolyphosphate as powder detergent additives, containing SiO2 for 2-6% of the dimethyl silicone oil (1500c.s) emulsion and anhydrous sodium tripolyphosphate mixed with the emulsion dosage of 10-40%, the formation of hydrates as additives.
For metal cleaning fluid, alkali resistance is required, the best when adding liquid products with transparent and defoaming activity.
7.6 Food Industry
Food-specific polysiloxane resin: Dimethyl Polysiloxane as the main body, containing less than 15% SiO2 food for the aqueous solution, with its emulsified products, others can be used directly with oil-based products, dosage control.
8. How to make silicone defoamer better?
Silicone defoamer has an excellent defoaming effect, even at very low dosages can be effectively eliminated and inhibits foam easy to use; high-temperature resistance, high temperature, high pressure, strong acid, strong alkali environment performance; environmental protection and reliability, will not cause pollution to the environment. Silicone-based defoamers are widely used in industrial applications. How to improve the competitiveness of your products and make them suitable for your test methods?
XJY Silicones is one of the leading silicone MQ resin and VMQ silicone manufacturers in China, with more than 30 years of R&D and manufacturing experience in the silicone industry and more than 15 related patents and technical support. Our silicone MQ resins can meet the needs of silicone defoamers and support the provision of diversified customized solution.
