 BASF is introducing additional grades of flame retardant polyamides (PA) and polybutylene terephthalates (PBT) and launching the new Ultramid® FRee and Ultradur® FRee product lines. The FRee grades are formulated without halogen-containing flame retardants and because of their light natural colour, are ideally suited for manufacturing electrical components in all colour tones. The suffix FRee thus stands for Flame Retardant and Electrical/Electronic (E/E) and also for design freedom and halogen-free. Ultramid FRee and Ultradur FRee employ innovative flame-retardant systems that are the result of years of research and development. At the same time, with their mechanical property profile and economy, the products establish new standards.BASF will introduce the first four new grades: • Ultramid FRee A3U40 G5, a PA66-based product that reliably satisfies the requirements of IEC 60335-1, the newest version of the safety standard for household appliances. • Ultramid FRee B3U31 G4, a PA 6 product with an optimised price/performance ratio that is tailored specifically to the requirement of circuit breakers. • The PBT line from BASF is being expanded through addition of Ultradur FRee B4440 G5 and B4450 G5. Both products satisfy the requirements of UL94's flame retardant class V0, the former at low wall thicknesses in particular. • Ultradur FRee B 4450 G5 is characterised by especially high tracking resistance. Tighter flame retardance requirements To ensure greater safety for consumers during operation of electrical household appliances, the regulations promulgated by the International Electrotechnical Commission (IEC) tightened the requirements for the flame retardance of household appliances about five years ago. The relevant requirements are summarised in the IEC 60335 standards. These so-called glow wire tests (acc. to IEC 60695-2-10ff) in particular are especially important in this regard. They determine whether a test specimen ignites upon contact with a glowing wire and how long it burns. This criterion has been made more stringent for certain critical cases involving electrical insulation. According to the current standard, any flame that is ignited on a test specimen must die out within five seconds while still in contact with a glowing wire at a temperature of 750 degrees Celsius. If this is the case, the material is given the rating GWIT 775. GWIT stands for Glow Wire Ignition Temperature, GWIT: 775 / 1.0 means that a glowing wire at 750 degrees Celsius was not able to ignite a one millimetre thick specimen of the material. Until a few years ago, the requirement called for the flame to die out within a minute after the plastic was ignited by a glowing wire at a temperature of 850 degrees Celsius. This result was documented in a so-called GWFI 850 rating. A different but similar regulation applies specifically in the USA. There, products are subject to the standards issued by Underwriters Laboratories (UL) these require that the material pass a combination of flammability (acc. to UL94) and ignition tests. Halogen-free, light coloured, compatible, economical This alone is challenging. Aspects that are not of technical nature but if they are extremely important for customers, then it further adds to the challenge. It has been possible for some time to comply with the more stringent requirements through use of halogen-containing flame retardants. However, a trend toward halogen-free flame retardant thermoplastics has taken hold in the market recently. One of the primary reasons for this is the European directive for disposal of electronic/electrical equipment waste, WEEE. It requires that components with halogen-containing flame retardants be sorted and disposed of separately. It is not always possible, however, to find a substitute for halogen-containing flame retardants. Red phosphorus, for instance, is an outstanding halogen-free flame retardant but has the drawback of a pronounced dark natural colour that carries over into the flame retardant component. On the other hand, the E/E industry has an increasing preference for light-coloured plastics. For instance, switches, connectors and circuit breakers in many household and industrial applications are often kept light in colour to satisfy special design requirements or prevent mix ups during assembly. These colours can be achieved only through use of colour-neutral flame retardants. Effective flame retardants must satisfy a large number of other requirements as well. They must not only harmonise with the matrix material, but also exhibit the correct behavior in the extremely sensitive interplay with numerous other additives during compounding and subsequent processing. These include synergists and colourants as well as reinforcement component such as glass fibres. They must also be priced competitively. Alternatives to red phosphorus in the form of organic nitrogen or phosphorus compounds, for instance, are quite expensive. The new members of the FRee family from BASF have succeeded in combining performance and economy. Thin but safe The new members of the FRee product line can be used with a variety of colours, giving designers greater possibilities. The impact-resistant Ultramid FRee A3U40 G5, for instance, successfully passes the glow wire tests called for by the tighter regulations in IEC 60335-1 starting at a thickness of one millimetre. This corresponds to the rating GWIT: 775 / 1.0. This is noteworthy, since at identical heat input, the ignitability of a material increases with increasing surface/volume ratio. Generally, the thinner the part, the easier it is to ignite. As a result, the new FRee polyamide provides considerably greater freedom when designing switches and thin-walled housing with snap fits. Thinner walls also mean optimal use of the available space, which translates into lower material costs. The new Ultramid FRee B3U31 G4 in particular satisfies the demanding circuit breaker requirements regarding flammability and ignitability starting at a wall thickness of one millimetre. Moreover, it is characterised by a very favourable price/performance ratio and incorporates a new type of thermal stabilisation system that reduces yellowing significantly. This makes the material extremely color-stable, reflecting the current trend in the circuit breaker market, where ever-lighter colours even approaching white, are desired. Ultradur FRee B4440 G5, the first new PBT, even achieves the highest V0 rating according to UL 94 at a wall thickness of 0.4 millimetres. PBT materials that offer this rating for very thin walls without the use of halogen-containing flame retardants while additionally giving customers the benefit of a light natural colour have appeared on the market only recently. The material is very well-suited for applications that call for outstanding dimensional stability, e.g. lamp sockets, connectors and sensors and also control unit housings such as those for electronic control units (ECUs) in automobiles. In Ultradur Free B4450 G5, the focus is on exceptional tracking resistance, measured as the so-called Comparative Tracking Index (CTI). This property is important when it comes to insulating very high voltages. The extremely high CTI of 600 for Ultradur FRee B4450 G5 makes it possible for component designers to reduce the spacing between contacts and thus shrink the housing and save material. Designed for a growing market The new FRee plastics are expected to have considerable opportunities for growth. In 2009, about 280,000 tons of flame-retardant polyamides and polybutylene terephthalates were sold. The fraction of halogen-free materials, however, differs greatly between these two resins: while almost half of the flame-retardant polyamides fall into this category, less than five percent of PBTs do. At an estimated six to ten percent per year, the growth rates of halogen-free flame-retardant engineering plastics is considerably higher than that of flame-retardant plastics overall. PBT is probably at the upper end of this range, since the demand for halogen-free products is especially high here. For further details please contact: BASF Corporation, North America Web: www.basf.com |
