Rapid-cure epoxies and polyurethanes

The big news on the Dow (Schwalbach, Germany and Midland, Mich.) stand at JEC Europe 2014 was Dow Automotive’s new, trademarked VORAFORCE 5300 epoxy resin family, capable of 90 second cycle times in automotive composite fabrication.

The big news on the Dow (Schwalbach, Germany and Midland, Mich.) stand at JEC Europe 2014 was Dow Automotive’s new, trademarked VORAFORCE 5300 epoxy resin family, capable of 90 second cycle times in automotive composite fabrication. The resin’s extremely low viscosity (15 mPa/s) reportedly gives it good “persistent flow” throughout the preform and helps reduce press tonnage requirements. Dow also reported that the resin offers mechanical performance on par with competitive epoxies as well as thermal performance of about 120°C/248°F. Its internal mold release eliminates the need for external mold release and the associated costs. Notably, VORAFORCE 5300 is classified as nontoxic according to the European Union’s REACH 2015 standard, and the VDA-278 test shows volatile emissions are close to zero, an important factor for applications adjacent to a vehicle passenger compartment.

The company also premiered a number of other epoxies in a variety of categories. Its VORAFORCE 5200 series, for example, offers low viscosity, high flow and fiber wetting and rapid cure (4 and 18+ minutes, coupled with a long possible injection time at very low viscosities) for large glass, carbon or aramid fiber-reinforced composite parts that require rapid injection. And Dow’s

VORAFORCE 5100 series reportedly delivers even faster production (cure in less than three minutes), with similar processing, capability, strength and quality. Dow says these features make it suitable for resin transfer molding (RTM) of automotive and commercial transportation components.

Also new was the VORAFORCE TW 1100 polyurethane series formulated with an out-time and cure profile that permits filament winding of one-piece 110-kV composite sections for large electrical transmission cable poles and, thus, complements Dow’s available range of polyurethane systems for smaller poles (e.g., 10 kV). In this application (see photo), VORAFORCE systems are said to help improve elongation, toughness, and crack resistance as compared to conventional materials and other type of resins. Advantages are said to include a fast reaction profile and workability in secondary cutting and drilling. Dow has developed a complementary UV-resistant polyurethane finishing system, which can be wound in a one-step production process to add a protective layer to the pole.