Fire safety and environmental protection – Ticona complies with strict environmental directives

From televisions and cell phones to washing machines – engineering thermoplastics today are enabling the electrical and electronics industry to produce increasingly powerful appliances in ever smaller dimensions. “But to protect human life, property and the environment, these polymer components have to guarantee very high fire safety,” stresses Dr. Jürgen Troitzsch, a fire protection expert from Wiesbaden/Germany. This can be achieved by adding flame retardants. However, new constraints have been placed on the use of flame retardants by two EU Directives: the Waste Electrical and Electronic Equipment Directive (WEEE) and the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Directive (RoHS). Manufacturers and suppliers therefore face new challenges.

Topics:

1. WEEE and RoHS - Directives set the pace for innovation
2. Celanex® XFR - The new flame retardant halogen- and antimony-free PBT
3. Lead-free soldering thanks to Vectra® LCP and Fortron® PPS

1. WEEE and RoHS: Directives set the pace for innovation

The new recycling and environmental provisions will apply as of August 2005. Retailers and manufacturers will then have a duty to take back post-consumer electrical and electronic equipment. In addition, as of July 2006, products that contain brominated flame retardants must be separately sorted. The costs incurred in the separate collection, recovery or disposal of electrical and electronic scrap have to be borne by the manufacturers. To avoid these additional costs, the electrical and electronics industry is relying on forward-looking solutions such as halogen-free flame retardant systems.

The new EU directives have driven the development and launch of novel phosphorus-containing flame retardants. These salt-like, halogen-free compounds are stable up to temperatures of 350°C, which makes them ideal for engineering thermoplastics in the electrical and electronics sector. Even very thin components (from 0.8 mm) fulfill the strict flame retardancy requirements of the US Underwriters Laboratories (UL) 94 V-0 test. Phosphorus-containing flame retardants are particularly suitable for flame-retardant modification of polyamides and linear polyesters. Flame-retardant polybutylene terephthalate (PBT) is a good example. With this polymer, it was previously only possible to achieve a technically satisfactory property profile with brominated flame retardants. “With phosphorus-containing flame retardants, however, it is now possible to meet the high flame retardancy requirements specified for connectors, relays and electronic installations,” explains Dr. Troitzsch.

Tests to ensure maximum safety
These components made from high-tech polymers are now indispensable in the electrical and electronics sector. The latest developments, including miniaturization, would not be possible without them. To ensure the fire safety of the materials and finished components, the relevant standards specify different test methods: for example, an outbreak of fire is simulated with a Bunsen burner or a faulty equipment part with a glow wire. The aim of these tests is to create realistic conditions such as would occur with an open flame, overheated wires or a short circuit. In these situations, flame retardants play a key role in ensuring increased safety. Their function is to prevent a fire or delay it as long as possible.

No chance for flames
Flame retardants work on a chemical and physical level. They interrupt the combustion process in the gas phase or on the surface of the product. In the gas phase, flame retardants are involved in chemical reactions that remove high-energy, flame-propagating radicals. On the surface they form a carbon-like layer by decomposition and cross-linking. This protects the material underneath from heat and flame attack. At the same time, there is physical intervention in the combustion process as a result of dilution with the non-flammable gases and water vapor that are formed.

Conventional flame retardants on the way out
“Halogen-free flame retardant systems are a genuine alternative for the electrical and electronics sector,” insists Dr. Troitzsch. “From a present-day viewpoint, there are environmental objections to certain flame retardants.” Until now, halogenated flame retardants have been widely used in electrical and electronic equipment because of their obvious advantages. They are economic, universally suitable and very effective – without unduly influencing the property spectrum of the modified plastic. Other flame retardants have only limited practicability. Phosphorus-containing compounds, for example, are very effective but have previously not been able to satisfy fire safety requirements in certain engineering thermoplastics such as PBT. Inorganic and nitrogen-containing flame retardants are barely effective and can also severely impair the properties of the modified plastic.

Directives drive eco-friendly development
Since 1994, the European Commission has been drawing up priority lists for risk assessment of existing chemicals, including certain flame retardants. Now substances such as penta- and octabromodiphenylether have been banned. In February 2003, two EU directives concerned with the disposal of electrical and electronic scrap and the restriction of certain hazardous substances in electrical and electronic equipment came into force at the same time. The WEEE Directive (Waste Electrical and Electronic Equipment) regulates the reuse, recycling and recovery of waste electrical and electronic equipment. The aim is to minimize the risks and environmental damage arising from the reprocessing and disposal of electrical and electronic scrap. Complementing this Directive, the RoHS Directive (Restriction of the Use of Certain Hazardous Substances) restricts the use of certain brominated substances and heavy metals in electrical and electronic equipment. These will be banned as of July 2006.

Prospects for a halogen-free future
“Halogen-free flame retardants have gained increasing importance in the electrical and electronics sector,” confirmed fire protection expert Dr. Troitzsch. Throughout the world, major manufacturers are switching to halogen-free systems. Here the new, highly effective metal phosphinate flame retardants are filling an important gap that previously existed in terms of halogen-free PBT products. “They will help companies solve the challenges they face in developing completely halogen-free product ranges,” summed up Dr. Troitzsch.

Presentation (pdf. version):
Dr. Jürgen Troitzsch:
Fire safety and environmental protection: How companies can meet the challenge

2. Celanex® XFR – The new flame retardant halogen- and antimony-free PBT

Ticona has developed a new range of polybutylene terephthalate (PBT) grades which are free from brominated flame-retardant agent.  With Celanex® XFR Ticona meets the demanding environmental requirements and launches a product which offers in time alternatives for the future.

Flame-retardant PBTs have been firmly established in the electrical/electronic market for many years. "Up to now there hasn't been any real alternative to brominated flame-retardant agents which also meet the requirements of UL 94 V-0 – one of the strictest flammability classifications", explains Dr. Tilo Vaahs, Marketing Manager Industries. This flammability rating is based on a flame ignition test used by the American Underwriters Laboratories (UL).

All flame-retardant without bromine or antimony
The new Celanex XFR range consists of four grades: one unreinforced and three reinforced with 10, 20 or 30 percent glass fibers. The patented flame-retardant system uses an organic phosphorus compound. Four main features distinguish it from other phosphorus-containing flame-retardant systems: High efficacy, thermal stability up to 300 degrees Celsius, virtual absence of migration and emissions, and problem-free coloration of the compounds. The low density of the XFR product range is another advantage, especially from a cost viewpoint.

PBTs are used in large and small electrical equipment items or appliances, electromechanical components (plugs, switches, relays), and in household and industrial installation work. The need to develop a new range of products resulted from new EU directives aimed at improving safety and environmental protection. Ticona's new PBT grades, whose flame-retardant systems contain neither bromine nor antimony, still retain virtually all the good mechanical and electrical properties of conventional PBTs. Compared with other halogenated compounds, their high tracking resistance (CTI value) and excellent UV stability offer added product appeal.

Currently there are a number of individual national, European and international standards for electrical and electronic equipment makers. In addition, there are numerous major test marks and a constant stream of new directives. "This is driving up costs in the whole industry but at the same time it's also adding to the pressure for innovation", comments Dr. Tilo Vaahs. The need to develop new product ranges in good time is therefore paramount, he explains. "We have to respond to future directives or laws even before they come into force", he continues. And Ticona, the Kelsterbach-based polymers specialist, has succeeded in doing just that with the launch of Celanex XFR.

Capability profile of Celanex® XFR:

Online Seminar:
Access is now available for the recently held Ticona online seminar: "Celanex® XFR – halogen- and antimony-free flame-retardant" (duration ca. 1 hour).

If you are interested in viewing the presentation, please send an email to infoservice@ticona.de with the subject “Online Seminar Celanex XFR”. Please let us know your language preference (available languages: English, German, French). Upon receipt of your email, we will send you the required access data.

Präsentation (pdf Version):
Sean Kemp, Ticona UK Ltd.
"Celanex® XFR – halogen- and antimony-free flame-retardant"

3. Lead-free soldering thanks to Vectra® LCP and Fortron® PPS

The high-performance polymers Vectra® LCP and Fortron® PPS withstand the higher temperatures of lead-free soldering without any problem and can be very easily recycled.

Preparing for the new legislative situation early on is not only beneficial to the environment but it also helps companies get the jump on their competitors. Many brand manufacturers in the electrical and electronics industry, such as Philips and Fujitsu Siemens, have already switched to lead-free soldering processes. The use of lead-free soldering pastes, however, means that soldering has to be carried out at temperatures some 30°C higher than in conventional soldering processes. In reflow soldering, which is the process most commonly used by the industry, the maximum temperatures are between 250 and 265°C. The components being soldered are exposed to these extreme temperatures for up to 15 seconds.

The heat resistance requirements for the insulating material in lead-free soldering are very high. In surface-mounted devices (SMD), particularly, the carrier materials must be capable of withstanding the increased temperatures. This is an ideal application for LCP and PPS. Both liquid crystalline polymer and polyphenylene sulphide offer excellent property profiles. The two materials have a high heat deflection temperature (HDT-A > 260° for stressed components). In addition, they feature low expansion coefficients in the area of the circuit board and excellent dimensional stability. Vectra LCP and Fortron PPS absorb little or no water and are resistant to fluxes and cleaning agents.

The following Vectra LCP and Fortron PPS grades have a very high heat deflection temperature and a high melting point and are therefore suitable for lead-free soldering:

GradeHDT-A                           Melting point

Fortron 1130L4                      265°C up to290 °C
Fortron 1140L4                      270°C up to290 °C
Fortron 6165A4                      270°C up to290 °C
Vectra E130i                           276°C up to 335 °C
Vectra T130                            301°C up to 370 °C
Vectra S135                            340°C up to 355 °C
Vectra S471i                           323°C up to 355 °C
Vectra E471i                           270°C up to 335 °C
Vectra E820i Pd                     220°C up to 335 °C
Vectra E820i LDS                  220°C up to 335 °C