Rigid Foam Surfactants

Polyester- and polyether-based rigid urethane foams generally require a surfactant, whether expanded with COj from the water-isocyanate reaction, or with an inert blowing agent such as fluorocarbon. Without surfactant the foam may collapse or have a coarse cell structure. Castor-oil-based systems generally do not require surfactants, but better results will be obtained if they are used (20). 

Surfactants used in rigid foams range from ionic to non-ionic types to the silicones. Anionic surfactants (those which contain active hydroxyl groups) should not be added to an isocyanate-containing foam component (20). 

The most widely used surfactants are copolymers based on dimethyl polysiloxane and polysiloxanes. Some of these silicones are prepared with ethylene and propylene oxides. Some silicones contain Si- 

0-C linkages and are hydrolytically unstable others do not contain a silicone-carbon bond and are stable. In general, higher-viscosity silicone copolymers are more efficient and wiU provide foams with finer cell structures. Surfactants are used at the 0.5% to 1% level in rigid urethane foams. With too little silicone foam, cell structure is large. Too much silicone does not affect the foam properties, but is wasteful. There is no known health hazard with the use of silicones (20). 

Whittington, L.R., Whittington s Dictionary of Plastics, 2nd Edition, Sponsored by The Society of Plastics Engineers, Techno-mic Publishing Co., Westport, Connecticut (1978). 

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Most thermoplastics and thermosets can be foamed, many of them into either flexible or rigid foams. The choice is controlled by the blowing agent, additives, surfactants, and mechanical handling. Some polymers can be expanded as much as 40 times their original density and still retain a substantial part of their strength. Most commercial foams are expanded to derisities of two to five pounds per cubic foot. (Water is 62 pounds per cubic foot.)... 

Many choices of surfactants are commercially available for use in various foams such as flexible foams, HR foams, rigid foams, etc. 

Alkasil . [Rhone-POulenc Surf.] Sili-c(Xie polyalkoxylate block copolymer intermediate for prod, of rigid polyurethane foams surfactants used in cosmetics, toilenies, textiles, coatir, and as release agent... 

Uses Raw material, combined with iso anates, to produce urethanes such as rigid foam, flexible foam, coatings, adhesives, sealants, elastomer systems for furniture, car seating, bedding, refrigerator insulation, paints/coatings, ski suits, playground surfaces, waterproof leisure wear also in surfactants and oil demulsifiers Carbalink HPC [Huntsman]... 

In addition, in many industrial practices, additional carbon dioxide or freon gas (a major sources of environmental pollution) may be introduced into the system as it cures. For rigid foams a low boiling liquid may be added to form additional bubbles. Appropriate catalysts and foam stabilizers or surfactants are added to control foam formation, cell size, and cure. The catalysts are either tin compounds or tertiary amines. The surfactants that are necessary to control the cell size are usually based on siloxanes. 

The surfactants regulate the interfacial tension in the foaming system and control uniform cell formation. High density, rigid foams do not require sophisticated surfactants, most commercial products perform well (2). 

Uses Surfactant for pentane-blown lamination and appliances, boardstock and pour-in-place rigid foams... 

Uses Surfactant, cell stabilizer for PU rigid and elastomeric applies. emulsifier, degassing agent in rigid foam applies. emulsifier tor dual-density shoe sole applies. 

Uses Low foam surfactant, emulsion stabilizer, dispersant, wetting agent, antistat for rigid PVC, vise, control agent... 

Uses Surfactant for use in rigid PU foams appiics. incl. lamination, spray, high index systems, pour-in-place rigid foams nonsilicone compat. with high polyester B-sides... 

Stmksilon 8026 surfactant, silicone PU Stmksilon 8015 Stnikslon 8017 Stmksilon 8018 Stmksilon 8023 Stmksion 8030 surfactant, silicone PU rigid foams Struksilon 8002 Stmksion 8005 Stmksilon 8007 Stmksion 8010 surfactant, silicone PU shoe systems... 

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