Urethane cast elastomers

The late 1950s saw the emergence of cast elastomers, which led to the development of reaction injection mol ding (RIM) at Bayer AG in Leverkusen, Germany, in 1964 (see Plastics processing). Also, thermoplastic polyurethane elastomers (TPUs) and Spandex fibers (see Fibers, elastomeric) were introduced during this time. In addition, urethane-based synthetic leather (see Leather-LIKEmaterials) was introduced by Du Pont under the trade name Corfam in 1963. 

Rotational casting elastomers, 204 Rubber, urethane, 201 Rubberlike polymers, 18 Rubber-modified blends, 149 Rynite, 21... 

Thermoset polyurethanes are cross-linked polymers, which are produced by casting or reaction injection molding (RIM). For cast elastomers, TDI in combination with 3,3,-dichloro-4,4,-diphen5lmethanediamine (MOCA) are often used. In the RIM technology, aromatic diamine chain extenders, such as diethyltoluenediamine (DETDA), are used to produce poly(urethane ureas) (47), and replacement of the polyether polyols with amine-terminated polyols produces polyureas (48). The aromatic diamines are soluble in the polyol and provide fast reaction rates. In 1985, internal mold release agents based on zinc stearate compatibilized with primary amines were introduced to the RIM process to minimize mold preparation and scrap from parts tom at demold. Some physical properties of RIM systems are listed in Table 7. 

The use of urethane elastomers should markedly increase from 8 to nearly 22 pounds per car. The use of TPU and cast elastomers is projected to decrease marginally while RIM urethane elastomer increases four-fold. With the successful use of RRIM composite urethane automotive use is projected to be 4 pounds per car. Thus, the use of all types of urethane elastomer should increase from 8 pounds in 1979 to a projected use of nearly 22 pounds per car in 1985. 

Chem. Descrip. Linear poly (ethylene glycol 1,4-butanediol adipate) Uses PU intermediate for microcellular cast elastomer applies, such as shoe soles, and for sol n. coalings, adhesives, and thermoplastic urethanes... 

Catalysts for urethane applications are sold by Air Products (Dabco), Abbott (Polycat), Kao Corp. (Kaolizer), Tosoh Corp. (Toyocat), and Union Carbide (Niax). Organic mercury compounds were used in cast elastomers and in RIM systems to extend cream time, ie, the time between mixing of all ingredients and the onset of creamy appearance, but are no longer used today because of toxicity concerns. 

Rapid growth of urethane technology can be attributed to the development of catalysts. Catalysts for the isocyanate-alcohol reaction can be nucleophilic (e.g., bases such as tertiary amines, salts and weak acids) or electrophilic (e.g., organometallic compounds). In the traditional applications of polyurethanes (cast elastomers, block foams, etc.) the usual catalysts are trialkylamines, peralkylated aliphatic amines, triethylenediamine or diazobiscyclooctane (known as DABCO), N-alkyl morpholin, tindioctoate, dibutyl-tindioctoate, dibutyltindilaurate etc. 

Plasticizers, 53% unsaturated resins, 23% alkyd resins, 13% Hexible urethane foams, 90% coatings, 4% cast elastomers, 2%... 

Urethanes are processed as mbber-like elastomers, cast systems, or thermoplastic elastomers. The elastomer form is mixed and processed on conventional mbber mills and internal mixers, and can be compression, transfer, or injection molded. The Hquid prepolymers are cast using automatic metered casting machines, and the thermoplastic peUets are processed like aU thermoplastic materials on traditional plastic equipment. The unique property of the urethanes is ultrahigh abrasion resistance in moderately high Shore A (75—95) durometers. In addition, tear, tensUe, and resistance to many oUs is very high. The main deficiencies of the urethanes are their resistance to heat over 100°C and that shear and sliding abrasion tend to make the polymers soft and gummy. 

Balas, A., Palka, G., Foks, J., and Janik, H., Properties of cast urethane elastomers prepared from poly( e-caprolactone)s,... 

The average of 8 pounds per car of urethane elastomer was composed of 1.3 pounds of TPU, 4.8 pounds of RIM thermoset elastomer and 1.9 pounds of cast thermoset urethane. 

Sample formulations of cast urethane elastomers applicable to conventional industry processing techniques were developed, and the physical properties of the resulting products determined. 

Adiprene . [Uniroyal Uniroyal Chem. Ltd.] Urethane elastomers for cast films and coatings, footwear, cable jackets, belts, hose, coated fabrics, rolls, molded goods. 

Aqualease. [Gemge Mann] Silicone emulsions release scents for casting molds, cast urediane elastomer and integral skin urethane foams, epoxies, filled polyester, vinyl ester resins. 

Formrez , [Witco] Adipate polyesters or polyether triok used for coatings, chain extenders, cast polyurethane elastomers, microcellular urethanes, potting compds., enctqrsulating agents, print-iiig tolls, coatings, adhesives. 

Calthane. [CalPolymas] Two-component urethane elastomer for flexible and rigid castings, prosthetics, underwater sports equipment, optical lenses, art objects, mech. devices, flexible windshields, industrial tubing or sheeting, toys, adhesives. 

Uses Soft segment In formulation of elastomers such as thermoplastic urethanes, coatings, fibers, adhesives and sealants, cast urethanes, and copolymers... 

Uses Soft segment or extender in formation of elastomers such as thermoplastic urethanes, polyether esters, polyether amides, coatings, adhesives and sealants, casting resins, and urethane foams Features Resist, to microbial attack, low temp, flexibility and elasticity Properties APHA 50 max. liq. sol. in most org. solvs. and water m.w. 250 sp.gr. 0.991 (40 C) acid no. 0.05 hyd. no. 408.2-498.4 flash pt. 180C 0.03% water... 

Uses Chemical intermediate prod, of light-stable, weather-resist, industrial coatings, elastomers, and foams for paints (metal finishing for automotive, aircraft, machines), coatings (wood, plastics, textiles, leathers, flooring), elastomeric casting compds. and mastics, adhesives prod, of urethane-acrylate resins Manuf./Distrib. Aldrich Fluka Sigma... 

Uses Polyol for urethanes, sol n. coatings, elastomers, castings, and solv.-free systems... 

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