Reaction injection molding polyurethanes

Siloxane containing polyester, poly(alkylene oxide) and polystyrene type copolymers have been used to improve the heat resistance, lubricity and flow properties of epoxy resin powder coatings 43). Thermally stable polyester-polysiloxane segmented copolymers have been shown to improve the flow, antifriction properties and scratch resistance of acrylic based auto repair lacquers 408). Organohydroxy-terminated siloxanes are also effective internal mold release agents in polyurethane reaction injection molding processes 409). 

Lee, L.J. Polyurethane reaction injection molding Process, materials, and properties. Rubber Chem. Technol. 1980, 53, 542. 

Bayer Bayflex elastomeric polyurethane reaction injection molding (RIM) is a two-component diphenylmethane diisocyanate- (MDI)-based liquid system produced in unreinforced, glass-reinforced, and mineral-Zmicrosphere-reinforced grades. They possess a wide stiff-... 

In polyurethane reaction injection molding technology, self-releasing systems are under investigation. Composition of reactive components (polyols and isocyanates) is used to develop systems which do not require release agents. 

Bruins PF (ed) (1976). Unsaturated Polyester Technology, Gordon Breach Science, New York. Castro, J (1980). Mold Filling and Curing Studies for the Polyurethane Reaction Injection Molding Process, Doctoral Dissertation, University of Minnesota, Minneapolis, Minnesota. Castro JM, Macosko CW (1982). AIChE J. 28 250. 

The sandwich-type stmcture of polyurethanes with a smooth integral skin produced by the reaction injection molding process provides a high degree of stiffness as weU as exceUent thermal and acoustical properties necessary for its use in housing and load-bearing stmctural components for the automotive, business machine, electrical, furniture, and materials-handling industry. 

The major uses of aniline are in the manufacture of polymers, mbber, agricultural chemicals, dyes and pigments, pharmaceuticals, and photographic chemicals. Approximately 67% of the wodd production of aniline is used in the manufacture of rigid polyurethanes and reaction-injection-molded (RIM) parts for the constmction, automotive, and durable goods industries. 

The largest segment of the CASE family of polyurethanes are elastomers. Cast polyurethane elastomers reached a new dimension when high pressure impingement mixing led to reaction injection molding (RIM). This technology is used widely in the automotive industry, and reinforced versions (RRIM) and stmctural molded parts (SRIM) have been added in more recent years. 

Polyurethanes are useful in numerous applications such as reaction injection molding, rigid and flexible foams, coatings and adhesives. However, due to the high reactivity of the isocyanate group [96], yielding either dimers, via self-condensation or a carbamate via the reaction with an alcohol, the A,jB-monomers have to be produced in-situ in the reaction vessel. 

C.E. Miller and B.E. Eichinger, Analysis of reaction-injection-molded polyurethanes by near-infrared diffuse reflectance spectroscopy, J. Appl Polym. ScL, 42, 2169-2190 (1991). 

Rigid polyurethane foams account for 80% of MDI use, especially for construction (about half of this use), refrigeration, packaging, and tank and pipe insulation. Other uses are reaction-injection molding (RIM) applications (13%) and cast elastomers (2%). 

Write out the complete reactions for polyurethane production starting with toluene, natural gas, air, water, and salt, as sketched in Figure 11-8. Use 1,4-butane diol for the glycol starting from butane. Why is this process preferable for reaction injection molding of automobile parts compared to Nylon or PET ... 

It is impossible to list representative properties for the Reaction-Injection-Molded polyurethane structural foams, because their properties can be varied over a wide range depending on the specific application. The foams can be very tough, resilient, blown elastomers or highly rigid structural foams. Furthermore, very recent develop-... 

The liquid monomers are suitable for bulk polymerization processes. The reaction can he conducted in a mold (casting, reaction injection molding), continuously on a conveyor (block and panel foam production), or in an extruder (thermoplastic polyurethane elastomers and engineering thermoplastics). Also, spraying of the monomers onto the surface of suitable substrates provides insulation barriers or cross-linked coatings. 

Miller, C.E. and Eichinger, B.E., Analysis of Reaction-Injection-Molded Polyurethanes by Near-Infrared Diffuse Reflectance Spectroscopy /. Appl. Polym. Sci. 1991, 42, 2169-2190. 

There are no generalized models that include all these variables for thermosetting polymers. However, extensive work has been done on the viscosity of polyurethanes [9, 10] used in the reaction injection molding process. An empirical relation which models the viscosity of these mixing-activated polymers, given as a function of temperature and degree of cure, is written as... 

RIM Abbreviation for reaction injection molding. The RIM process involves the rapid metering and mixing of polyurethane reaction ingredients, followed by their injection into a mold. It allows the rapid production of molded polyurethane components. 

MDI [4,4 -methylenebis (phenylisocyanate)] accounted for almost 85% of the worldwide demand for aniline in 2000. MDI is used primarily to make rigid polyurethane foam and polyurethane elastomers. MDI growth is expected to be 6% to 8% per year during the 2000 s as its use continues to increase in the construction industry (the largest user of rigid polyurethane foam) and the auto industry (the largest user of reaction-injection molding plastics). The aniline uses are shown in Table 20.3255. 

The late 1950s saw the emergence of cast elastomers, which led to the development of reaction injection molding (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-LIKE MATERIALS) was introduced by Du Pont under the trade name Corfam in 1963. 

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. 

Reaction injection molding (RIM) is a fast, low-pressure, low-temperature, low-cost process for one-step conversion of reactive liquids into large finished solid plastic products. Liquid polyol and liquid diisocyanate are mixed by impingement, pumped instantly to fill a large mold cavity, and polymerize/ cure rapidly to form a thermoset polyurethane product. The cured polymer may be a stiffly flexible product such as automotive bumper covers, front ends, and trim or a rigid foamed product such as furniture and housings (cabinets) for computers, business machines, TY and radio. 

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