The new materials are also said to offer high strength and stiffness combined with good toughness and are designed for components subject to high mechanical load, such as structural parts in industrial machines that must meet flame retardance requirements, and moulded case circuit breakers (MCCB).
“In addition, they are a substitute for die-cast metals and thermosets, when the high stiffness of these materials is not needed,” says Alexander Radeck, Applications Development Expert in the High Performance Materials (HPM) business unit. “Processors also benefit from the high design freedom and cost efficiency afforded by injection moulding.”
Durethan BKV45FN04 is reinforced with 45 wt% short glass fibres. Its flame retardance package contains no halogens or red phosphorus. The high-modulus material can therefore also be coloured as desired. In terms of flame retardance, it passes Underwriter Laboratories’ UL 94 test, achieving the best classification of V-0 with test specimens just 0.4 mm thick.
“In the even tougher UL 94-5V test, the compound achieves the best rating of 5VA at just 1.0 mm, and that’s entered accordingly on the UL Yellow Card,” continues Radeck.
With a CTI A (Comparative Tracking Index, IEC 60112) of 600 V, the material is highly tracking resistant. Electronic assemblies can therefore be positioned closer together without resulting in shorts or device defects caused by leakage current. Another of the material’s strengths is its high-voltage tracking resistance to DIN EN 60587 and ASTM D2303 (Inclined Plane Tracking, IPT). The test recreates how strongly the insulating capacity of a surface changes at high voltages outdoors when exposed to moisture and soiling.
“The Yellow Card lists a good IPT voltage for our material of 1 kV at 60 minutes tracking time,” explains Radeck. “That means it’s also suitable for components used in high-voltage battery systems in electric cars.”
The second product is on the verge of market introduction and contains over 50% glass fibres. With its halogen-based flame retardance package, it likewise achieves V-0 (0.75 millimetres) and 5VA classification in UL 94 testing (UL Yellow Card). The high flame retardance is also evident in glow wire testing to IEC 60695-2-12/13. For example, at 775°C, the product easily fulfils glow wire ignition temperature (GWIT) requirements.
“With these results, the material is destined for components subject to high mechanical stress, such as in household appliances (IEC 60335-1),” says Radeck. “It also has great opportunities for use in housing parts and covers of circuit breakers.”
The compound’s CTI A tracking resistance is high at 575°C (PLC 0 on the UL Yellow Card).
With their high glass fibre content, both of the materials display high stiffness and strength. Durethan BKV45FN04 has a tensile modulus of 16,000 MPa (freshly moulded). Despite glass fibre reinforcement, the melts of both thermoplastics are said to display excellent flow properties thanks to EasyFlow technology.
“Components can therefore be designed with thin walls, complex geometries and relatively long flow paths,” reports Radeck.