Specialty chemicals company Lanxess is expanding its portfolio of halogen-free, flame-retardant compounds based on polybutylene terephthalate (PBT) and polyamide (PA 6, PA 66). “In terms of properties and processing, our new materials are on par with, or even superior to, their counterparts containing halogen-based flame retardance packages. We believe that sales of these products will benefit in the future from global trends, such as Industry 4.0, electromobility and digitally networked building systems, household devices and consumer electronics,” explains Alexander Radeck, applications developer in the Lanxess High Performance Materials (HPM) business unit.
New additions to the PBT product line include materials with 13, 25 and 30% glass fiber reinforcement as well as a non-reinforced material that displays a high elongation at break of over 7% despite its halogen-free flame retardance package. It passes the standard fire tests of the U.S. testing organization Underwriters Laboratories, achieving the best classification. Another advantage is its high tracking resistance of 600 volts, according to the German company.
“We see good opportunities for this easy-flow material in components requiring high-level, consistent electrical insulation properties and high dimensional stability,” Radeck adds. One product has a glass fiber content of 20%. Like its “sister products”, this compound displays not only high flame retardance attributable to a low tendency toward corrosion in contact with metals, but also good thermal aging resistance and color stability at elevated temperatures, a wide processing window and good suitability for high-contrast laser marking.
Another PBT product targets applications in lighting and LED technology. Radeck: “Its light reflection of more than 94% at 450 nm is unusually high, meaning that when used as a housing material, it reflects LED light almost entirely.” It also offers high blue light resistance and high light-proofness even at thin wall thicknesses. The material further displays good mechanical behavior and a low tendency to warp, as Lanxess claimed.
Furthermore, a PBT compound is currently under development that shows good results in glow-wire testing . These tests assess the ignition properties and afterburn behavior of plastics that come into contact with overheated or incandescent metal parts. “Our material proves that not only halogen-based, but also halogen-free flame retardance packages can support good glow-wire resistance levels in PBT compounds,” says Radeck. The new material also achieves good results in the glow-wire testing of end products. “This test is very demanding because end products, which can have complex geometries and metal inserts, frequently display less favorable behavior than simple test specimens,” Radeck explains.
One new product among the halogen-free flame-retardant polyamide is optimized for laser transmission welding. It is a process increasingly used for joining electrical and electronic assemblies because it is associated with only limited thermal loading and is dust-free. In the color black, the material’s light transmission in the standard wavelength range for laser welding is still over 50% at a wall thickness of 1.5 mm. This ensures a high and rapid delivery of heat input during welding. The joint area melts faster for more cost-effective production. “The polyamide has a flame retardance package whose components display hardly any tendency towards blooming, meaning that virtually no deposits form on the mold surface during injection molding,” as Radeck says.
