Emulsions antifoaming agents

Antifoam. [CNC Int l.] Silicone and nonsilicone emulsions antifoam agents, foam suppressants. 

Defoamer 167. [A. Harrison] Silicone emulsion antifoaming agent for dyeing, finishing and printing. 

Quahty control testing of siUcones utilizes a combination of physical and chemical measurements to ensure satisfactory product performance and processibihty. Eor example, in addition to the usual physical properties of cured elastomers, the plasticity of heat-cured mbber and the extmsion rate of TVR elastomers under standard conditions are important to the customer. Where the siUcone appHcation involves surface activity, a use test is frequently the only rehable indicator of performance. Eor example, the performance of an antifoaming agent can be tested by measuring the foam reduction when the sihcone emulsion is added to an agitated standard detergent solution. The product data sheets and technical bulletins from commercial siUcone producers can be consulted for more information. 

In addition, even where foaming is not a specific problem in a boiler, carryover may occur, especially in lower pressure boilers with very high TDS (i.e., over 10,000 to 15,000 ppm TDS) because of the collapse of surface bubbles. This leads to BW aerosol generation and entrainment of the spray in steam. Under these circumstances, antifoam agents such as polyamides are useful in preventing these entrainment problems. Furthermore, the antifoaming action of polyamides is often enhanced by protective colloid materials such as tannins, and consequently, formulations containing polyamide emulsions in an alkaline tannin base are available. 

Have a low air-entraining capability during mixing when a suitable antifoaming agent is used in the emulsion or redispersible powder. 

Recently, emulsions based on oligomethylsiloxane liquids have been widely used as antifoaming agents to suppress or prevent foam in aqueous, nonaqueous and low-aqueous solutions, and as separating lubricants in pressure molds for tyre production. They are also used in foundry work to manufacture rods and in the production of elastomers and plastics. 

Other silicone antifoaming agents can be based on oligomethylsiloxanes of various viscosity and are prepared similarly. Instead of OS-2 solution, some emulsion brands use the Solvar solution or solutions of emulsifiers OP-7 and OP-10. 

To extinguish foam in aqueous media, it is advisable to use water emulsion silicone liquids PMS-154A, PMS-200A, etc. to ease the distribution of the antifoaming agent on the surface of the foaming mixture. 

Highly effective antifoam agent which incorporates an efficient emulsifying system to ensure good storage properties and stable emulsions when diluted to stock or working conditions. 

Dimethicones of various viscosities are widely used in cosmetic and pharmaceutical formulations. In topical oil-in-water emulsions dimethicone is added to the oil phase as an antifoaming agent. Dimethicone is hydrophobic and is also widely used in topical barrier preparations. Therapeutically, dimethicone may be used with simethicone in oral pharmaceutical formulations used in the treatment of flatulence. Dimethicone is also used to form a water-repellent film on glass containers. See Table I. 

Polyglycol. [Dow Europe] Polyptc yl-ene glyccd antifoaming agent, coupler for pottery, ceramics, latex, emulsion paints, a c. formulations, lubricant... 

USE Substitute for cetyl ale in pharmaceutical dispensing, in cosmetic creams, For emulsions, textile oils and finishes, as antifoam agent, lubricant, and chemical raw material. 

Defomax. [Toho Chem. Industry] Nonionic suifactant/wax emulsion blend antifoaming agent for rubbos and plastics. 

Batch emulsion copolymerization of VAc and BuA was carried out using a nonionic emulsifier (30 mol ethoxylated nonylphenol, NP 30), a new oligomeric stabilizator (N-methylol acrylamide, AMOL), Nopco-1497 as antifoam agent, and ammonium persulfate (APS) as initiator by changing monomer ratios from 100 0 to 0 100 for VAc BuA in the loop reactor. The monomer ratio of VAc and BuA were changed in the copolymerization (VAc BuA 100 0, 90 10, 75 25, 60 40, 50 50, 40 60, 25 75, 10 90 and 0 100) at 70°C and 400 rpm constant stirring rate in the loop reactor. Some detailed information about loop reactor was given in literature... 

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