Free of halogens and red phosphorus - One reason is that many equipment manufacturers in the industry are now voluntarily agreeing to give preferential treatment to plastics with halogen-free flame retardancy properties. Polyamides whose additives are not only flame-retardant but also free of red phosphorus have been especially popular in recent times. “Our material meets precisely these requirements. It achieves excellent ratings in flame retardancy tests, has a wide processing window for injection molding and is perfect for components with very thin walls such as plug connectors, coil formers and tiny USB plugs,” explains Alexander Radeck, an expert in application development at LANXESS’ Semi-Crystalline Products business unit.
Many manufacturers of consumer electronics have stopped using halogenated flame-retardant plastics in a bid to become more eco-friendly. Their aim is to improve their image among end consumers by boosting the sustainability of their operations. More and more companies are opting for halogen-free flame retardant plastics that contain no red phosphorus because of its inherently dark color, which prevents the corresponding components from being given a light color. Color is a crucial design element and a safety feature in many applications. Red phosphorus can also cause corrosion when it comes in contact with metals in warm or moist conditions.
Excellent UL ratings
Tests conducted in accordance with standard UL 94 of the U.S. testing organization Underwriters’ Laboratories (UL) confirm the high flame retardancy of Durethan DP AKV 30 FN00. Test pieces between 0.4 and 3 millimeters thick passed the test and were awarded the classification V-0. Moreover, the thermoplastic is difficult to ignite and has a short flame time. At 960 °C, it achieved the best possible GWFI (Glow Wire Flammability Index) value for plastics in the glow wire test pursuant to IEC 60695-2-12 based on test piece thicknesses of between 0.8 and 3 millimeters. In the HWI (Hot Wire Ignition) and HAI (High Amp Arc Ignition) tests, the material was classified in the best performance level category (PLC 0), even at a test piece thickness of 0.4 millimeters. This makes it highly suitable as an insulating material in line with UL standard 508.
High CTI value with long-term heat resistance
The electrical properties of polyamide 66 are also rated very highly. For instance, its CTI A (Comparative Tracking Index, IEC 60112) value of 600 volts means it is very tracking resistant and therefore boasts the best possible classification (PLC 0) on the UL Yellow Card. The risk of short circuits and equipment faults resulting from leakage currents in applications is thus greatly reduced.
Even in air, this material, which is reinforced with 30 percent glass fibers, has high heat resistance in continuous use. “Tests to assess compliance with UL 746 B are currently under way and excellent Yellow Card values are expected for the Relative Thermal Index (RTI) with respect to all three load types specified in the standard,” explained Radeck. The material also boasts impressive mechanical properties. The high Izod impact strength (ISO 180-1U) of 55 kJ/m2 is just one noteworthy example.
The new polyamide 66 was designed to have a broad processing window for injection molding. According to Radeck, “This material can easily cope with wall thicknesses of well under one millimeter – for instance in plug connectors.” The material is used instead of flame-retardant PBT, polyamide 46 and polyphthalamide in many applications.
LANXESS (lanxess.com) is a leading specialty chemicals company with sales of EUR 5.06 billion in 2009 and currently around 14,400 employees in 23 countries. The company is represented at 42 production sites worldwide. The core business of LANXESS is the development, manufacturing and marketing of plastics, rubber, intermediates and specialty chemicals.