The European Union’s Restriction of Hazardous Substances (RoHS) and Waste in Electrical and Electronic Equipment (WEEE) directives earlier this decade added emphasis to the worldwide recognition of the effects that chemical compounds have on the health and safety of both humans and the planet. In response, several large corporations, such as Apple Computer, Nokia, Dell, and Sony Ericsson are developing phase out plans for brominated flame retardants (BFR’s). While Nokia has already eliminated BFR’s, Apple has made a commitment to ban all of them by the end of 2008, and Dell has pledged to do the same by the end of 2009.
In addition, antimony compounds, which are used as synergists with many brominated flame retardants, have come under close scrutiny. Antimony compounds are now on the European Union’s list of high priority substances to be considered for inclusion on the RoHS list, which would ban their use in the 27 European Union nations.
Meanwhile, the Swedish government lifted its unilateral, limited ban on the use of the flame retardant Decabromodiphenyl ether (Deca-BDE) in textiles, furniture and some electronic cables in response to a legal challenge from the European Union. This eliminated the inconsistency between its ban and the positive results from a 10-year E.U. risk assessment of the material that did not identify any significant risks in its use. This has left the E.U. with the vexing problem of how to resolve the contradiction between the RoHS Directive’s restriction on Deca-BDE and the positive scientific assessment of Deca-BDE.
Role of Eco-labeling
Eco-labeling, a voluntary system for identifying consumer products that avoid negative environmental effects, has also had a pronounced effect on the use of BFRs. Eco-labels are designed specifically to go beyond legal requirements like RoHS and REACH, and endorse best-in-class products and services that use advanced environmental benchmarks. Many eco-label systems prohibit the use of halogenated flame retardants in electronic products and require statements to eco-labeling organizations declaring their absence. Eco-labeling also plays a role in procurement, because various eco-label approved products and processes can be included as criteria in the bid process.
The result is a confusing set of standards for producers and consumers of BFR-containing materials and the requirement that many of these issues be resolved in a relatively short period of time. This has forced many manufacturers to implement crash programs to address the changes in policy and regulations as they occur.
As brominated flame retardant materials are phased out, flame retardant suppliers are rolling out new materials to replace them. Since most of the current alternatives are less efficient than BFRs, these new flame retardants will be system-based. That is, a group of different flame retardants will be assembled based upon the customer’s needs. However, this requires extensive R&D work to determine which system is appropriate. For consumers, a multitude of new options are available. Complicating matters is the fact that many of these changes occur with tight deadlines, leading to a mad scramble to find a system that works, not one necessarily optimized for the manufacturer’s process and the product’s end use.
Nanocomposite materials, especially clays and graphite, have shown promise as flame retardants. Nanocomposites work by creating a protective coat-like char and a cross-linking of the polymer matrix. This results in the formation of char and a reduction in the heat release rate. Char is the crust of partially burned material that forms on the surface of plastic material in a fire and robs the flame of fuel. Many companies have begun marketing nanocomposites concentrates as flame retardants, typically compounding them with magnesium hydroxide or aluminum trihydrate to improve overall performance.
Intumescent flame retardants, which foam up at combustion temperatures to help form a thick insulating char layer, have also seen a surge in activity. These FRs have limited applications due to problems with cost, poor processing, thermal stability, plate-out, and water sensitivity. Most of these flame retardants are either melamine or phosphorus-based compounds.
Tin-based flame retardants are seeing increased use as replacements for antimony-based materials. Tin functions as a char promoter in the resin substrate in both the vapor and condensed phase. Zinc stannate and hydroxystannate have been recommended for use as smoke, flame and carbon monoxide suppressants when used as a synergist with brominated flame retardants.
Overall, the changing environmental climate will continue to force both suppliers and consumers of flame retardants to improve on the impact that current materials have on the health of humans and the environment. This will require suppliers to constantly keep abreast of new developments in worldwide regulation of these materials as well as any new, more benign compounds that they can utilize to separate themselves from their competitors.