Hexion Inc., a supplier of epoxy resins, curing agents, and bonding pastes to wind turbine blade manufacturers around the world, introduces the EPIKOTE MGS Resin BP 535/EPIKURE MGS Curing Agent BPH 538 bonding system. This new bonding paste, developed specifically for today’s larger, high-performance rotor blades, combines outstanding strength and fatigue performance with the long processing time needed to manufacture lengthier blades.
As the wind energy industry migrates to larger turbines with longer, heavier rotor blades, a variety of production challenges have emerged. One drawback of conventional bonding paste has been that it can only remain exposed to air for a limited time before its adhesive performance suffers due to surface film formation, or carbamation. Manufacturers often found that they didn’t have time get the entire blade processed before the bonding paste would lose its efficacy—often in a little over an hour.
In response, Hexion developed a paste that would not form a film until after four hours of open time or longer, even at 70% relative humidity, allowing manufacturers additional time to lay down the paste and assemble the parts.
“As a recognized leader in resin systems for wind energy applications, we work closely with customers to develop innovative solutions to their particular product and process challenges,” says Johannes Meunier, Hexion Global Segment Leader, Composites. “BP 535 is an excellent example of a collaborative solution to the manufacturing problems posed by larger, heavier rotor blades.”
In addition to long processing time and high tolerance for environmental humidity, the EPIKOTE BP 535 resin system displays outstanding fatigue performance, improved by one order of magnitude over benchmark BP 435. It also exhibits good sag resistance at elevated temperatures, making it ideal for adhesion of vertical surfaces and across wide gaps. This adhesive resin does not bleed from vertical gaps even if parts are immediately cured at high temperatures (up to 80° C). This attribute, as well as the system’s solid TG after curing for only four hours, offer possibilities for cycle time reduction. Other process enhancing characteristics of this new bonding paste are a long pot life and a low exotherm.