Antifoam compounds

A 100% active siicone antifoam compound. May be emulsified to prepare stable silicone defoaming and antifoaming agents for all applications. 

The goals of these investigations were to examine the influence of the polymer structure and viscosity on the antifoam compound performance. Of particular interest was the influence of the compound viscosity on the antifoam performance at the higher temperatures typical of many foaming situations. 

Three new silicone antifoam compounds with optimized polymer structures and viscosities ranging from 26 000 to 100 000 mPa.s were compared with conventional silicone antifoams. 

The antifoam compounds were tested in 0.375% Mersolat H30, a sodium alkyl sulfonate with pH 6.5. The Persistence Value was calculated according to the formula Persistence Value = [mL KD/(seconds to 125 mL - seconds to KD)] x 150. The results at 23 °C and 70 °C are given in Tables 2 and 3, respectively. 

Antifoam compounds. Dow-Coming Corp. offers two 100% silicone compounds for nonaqueous foaming systems, A and Q, which are effective in concentrations of 1-50 ppm. and 0.1-150 ppm. Thus one small drop of Q stops foam in a whole gallon of liquid. Antifoam B, C, and H-IO emulsions (pH 6.5, 3.9, and 4.0) contain 10-30% active defoamer and are useful for control of aqueous foaming systems. 

A typical antifoam consists of an oil (polydimethylsiloxane or hydrocarbon), dispersed hydro-phobic solid particles (e.g., hydrophobized silica), or a mixture of both. The oil-solid mixtures are often called antifoam compounds. The weight concentration of the solid particles in compounds is around several percent (typically between 2 and 8). A strong synergistic effect between the oil and the solid particles is observed in the compounds — in most cases, the latter are much more efficient than either of their individual components, if taken separately. The compounds are used at a concentration below 0.1 wt%, whereas the oils are used at higher concentrations (up to several percent) due to their lower antifoam efficiency. The antifoams are usually preemulsified in the form of oil drops or mixed oil-solid globules of micrometer size. 

FIGURE 5.63 Schematic explanation of the optimal hydrophobicity of the solid particles in oil-solid antifoam compounds, (a) When an antifoam globule approaches the foam film surface, an asymmetric oil-water-air film of thickness forms, (b) The zone of contact in an enlarged scale. If the protrusion depth, dj,, of the solid particle is larger than the particle should be sufficiently hydrophobic (9 + 9o > 180°) to pierce the air-water interface and induce a film rupture however, if the particle is insufficiently hydrophobic (9 + 9q < 180°), it would stabilize the film. (c) On the other side, if the solid particle is overhydrophobized, then < PR < As and the particle is again unable to pierce the asymmetric fihn. ... 

FIGURE 5.65 Schematic presentation of the processes of antifoam exhaustion and reactivation of emulsified oil-silica antifoam compound. 

Silicone Antifoam Agent S 203, Silicone Antifoam Agent S 204, Silicone Antifoam Agent S 370, Silicone Antifoam Agent S 670, Silicone Antifoam Agent S 860 Silicone Antifoam Agent S 882 Silicone Antifoam Agent S 911 Silicone Antifoam Compound S 204. See Silicone Silicone Antifoam Emulsion SE 6 Silicone Antifoam Emulsion SE 9. See Simethicone Silicone Antifoam Emulsion SE 20 Silicone Antifoam Emulsion SE 21 Silicone Antifoam Emulsion SE 22 Silicone Antifoam Emulsion SE 23 Silicone Antifoam Emulsion SE 24 Silicone Antifoam Emulsion SE 25 Silicone Antifoam Emulsion SE 26 Silicone Antifoam Emulsion SE 27 Silicone Antifoam Emulsion SRE. See Silicone emulsion Silicone Antifoam Powd. ASP 15. See Silicone Silicone elastomer CAS 63394-02-5... 

Production of Silicone Surfactants and Antifoam Compounds in Detergents... 

Silanols are reactive silicone compounds which when reacted with silica gives very effective antifoam compounds. Silanol compounds have also been used in softergent applications, in many cases giving better, more durable softening than silicone fluids. 

By virtue of their structure, surfactants perform several functions in aqueous solution. Often, however, there are processes in which one uses a surfactant for a desired property and does not want the other properties inherent in the surfactant. For example, one may want detergency without foam. Modihcation of the surfactant molecule offers minimal relief. Consequently, antifoam compounds... 

Foam in machine dish and lanndry applications needs to be carefully controlled. Too much foam can overflow the machine. There are several inherent properties of antifoam compounds desired for detergent applications. The antifoam must have the ability to... 

Antifoam compounds for use in detergents can be found in many types of formulated products including dishwashing detergents and rinse aids, home laundry formulations, home laundry softeners, window cleaners, alkaline metal degreasers, hard-surface cleaners, acid cleaning of metals, bottle-cleaning formulations, and many others. 

A major application for antifoam compounds is in aqueous formulations such as detergents and softeners. A low concentration of antifoam compound is present in the formulation to allow more efficient filling of the bottles. In many operations, foam will cause the bottle to overflow, shutting down the bottling operation. 

Antifoam compounds are often used during the wash out and clean-up operations in detergent plants. In addition, many detergent plants use antifoam compounds in their effluent to control foam. ... 

Silicone fluids per se have both antifoam and defoaming attribntes, they can be modified by reaction with silica to make significantly more efficient antifoam compounds. Silicone-based antifoam compounds for use in detergents are composed of two major components silicone fluid and hydrophobic silica. The fluid polymer acts as a carrier to deliver the silica particles to the foam air-water interface, where film rupture then occurs. 

Very efficient antifoam compounds can be prepared by the reaction of silanol compounds with silica. The so-called in situ hydrophobized silica makes very efficient antifoam compound. 

The performance of silicone-based antifoam compounds is independent of water hardness. They are effective at very low addition levels in all types of surfactant systems normally present in detergent formulations and across a wide range of use conditions. Furthermore, silicones cause no yellowing on fabric. Thus, silicone-based antifoam compounds have a number of benefits over soap-based foam control systems. 

Hundred percent-active silicone-based antifoam compounds are normally referred to as silicone antifoam compounds. If the silicone antifoam is in water, it is referred to as antifoam emulsions. Mixtures of silicone antifoam compounds with nonaqueous dispersion or delivery systems also exist, to aid their dispersion in aqueous media. 

The unique properties of silicone-based antifoam compounds have led to their wide use by the detergent industry. They are active at low use levels in aU types of surfactant systems present in detergent formulations. Many custom-formulated antifoam compounds have been developed for use... 

Silicone antifoam compounds are made by hydrophobizing silica in silicone fluid. The process is conducted at a temperature of 200°C in the presence of a base catalyst, typically KOH. The powdered silica is dispersed into silicone fluid and mixed well. The KOH is added and dispersion is heated. Once the reaction temperature is reached, water gets distilled. Over a period of 4-8 h, the dispersion goes from opaque to translucent. 

---