Düsseldorf, October 15, 2024 – When it comes to manufacturing electric vehicles (EVs), there is a high level of demand for halogen-free, flame-retardant compounds based on polybutylene terephthalate (PBT) achieving the top V-0 classification in the UL 94 flammability test. Two new compounds from Envalior meet this requirement. Pocan® BFN4232HR for example, is specially designed for high-voltage applications in EVs, such as connectors and components in the charging system. While Pocan® BFN4221Z is designed for housings components, such as power capacitors, as well as busbars, connectors and power strips. Envalior is showcasing the new compounds during Fakuma 2024 at the Exhibition Center Friedrichshafen, in Hall B4, Stand 4302, Oct. 15 to 19, 2024.
“We have expanded our portfolio of products in this area to include two material variants, Pocan® BFN4232HR and Pocan® BFN4221Z, which also offer additional benefits, like hydrolysis resistance, tracking resistance and ease of processing, as well as optimum mechanical properties,” explains Lucas Lichius, Global Product Manager for PBT.
Class 3 classification in USCAR hydrolysis test
Pocan® BFN4232HR is specially designed for high-voltage applications in EVs, such as connectors and components in the charging system. The compound achieves Class 3 classification in specimen tests based on the stringent long-term hydrolysis tests of the US Society of Automotive Engineers (SAE/USCAR-2 Rev. 7). This shows that components made from the material are highly resistant and can do their job without any issues, even in hot and humid environments.
“The good result in the USCAR test is all the more remarkable because halogen-free flame-retardant additives normally reduce the hydrolysis resistance of PBT compounds,” says Lichius.
Top results in tracking resistance tests
The V-0 classification in UL 94 test (Underwriters Laboratories Inc) for the new product applies for specimen thicknesses down to 0.75 millimeters and is already listed on the UL Yellow Card under “All Colors”. This is important because high-voltage components are typically marked in different colors for safety reasons and to make assembly easier. Another benefit of the material is its high tracking resistance. In the color orange, for example, it achieved the best possible rating of CTI A 600 in the CTI A test (Comparative Tracking Index, IEC 60112). The high degree of tracking resistance, which was also confirmed for other colors, lowers the risk of electrical and electronic defects caused by the creation of electrically conductive paths on the surface of the thermoplastic. This allows electrical and electronic functions to be arranged more closely, resulting in smaller and more compact devices.
Reinforced with 25 % glass fibers by weight, another strength of the material is that it has extremely good processing properties compared with its peers in the same material class. When used at higher injection molding temperatures, for example, it does not tend to outgas self-igniting volatiles or substances that are dangerous from a working hygiene perspective.
“It is stable and safe to use within a wide process window, which is not something that can be taken for granted when it comes to this type of compounds,” Lichius explains.
Highly suitable for the overmolding of metal parts
Pocan® BFN4221Z, the second new PBT compound, offers optimized mechanical properties and has already been approved by OEMs. Key features include its high elongation at break of 2.8 percent (ISO 527-1,-2) and IZOD impact resistance (ISO 180) of 35 kilojoules per square meter, which is good for a material of this kind. Its tensile strain at break comes close to that of compounds with halogenated flame-retardant packages. This means the material can absorb more energy during deformation, which in turn prevents the component from breaking or cracking so easily under load.
“For example, the tensile strain at break ensures that snap fits do not deform and break before they snap into place. It also prevents thinner component areas from breaking under bending loads,” says Lichius. The structural material is also well suited for overmolding metal parts that are exposed to rapid temperature changes (thermal shock stability). Thanks to its high tensile strain at break and its thermal resistance, there is a low risk of stress cracks in the component in the event of sudden temperature changes.
Pocan® BFN4221Z also boasts high tracking resistance. The compound, which is reinforced with 20% glass fibers by weight, achieved the best possible result in the CTI A test, even in the color black. V-0 classification in UL 94 testing reflects its excellent flame-retardant properties even at very thin wall thicknesses of just 0.4 millimeters. Potential applications include housings for components such as power capacitors, as well as busbars, connectors and power strips.
For more information on the products and services provided by Envalior, visit www.envalior.com/en-us/products.html.
One potential application for Pocan® BFN4232HR is high-voltage connectors.
Photo: Envalior
About Envalior
Envalior is a global leader in Engineering Materials with over 4,000 employees worldwide. It was established in 2023 through the merger of Lanxess Performance Materials and DSM Engineering Materials. With a long track record of customer-driven innovation, Envalior specializes in developing sustainable and high-performance material solutions. Focus markets include Automotive, New Mobility, Electronics & Electrical, and Consumer Goods. For more information, visit www.envalior.com.
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Candace Roulo
