Flame retardants: is the customer always right? Brominated additives are a bete noire for OEMs trying for a green image, but perhaps for the wrong reasons. What then is the future for halogen-based flame retardants?

Plastics Engineering, July, 2007 by Peter Mapleston

Big names like Apple and Deli have gone public in recent months with commitments to stop using brominated flame retardants (BFRs) in the plastics they use. Some types have turned up in the environment and in breast milk, which in most people's book is a good reason to look for alternatives. Other types, however, have been given a clean bill of health, but OEMs still don't want to use them.

Working on the adage that the customer is always right, plastics and additives suppliers are trying hard to help these OEMs meet their commitments. But at the same time, there is a strong feeling that some BFRs will be in use for a good time to come. In terms of performance and fitness for purpose, in many applications there is still nothing that, as the saying goes, can hold a candle to them.

Joe Andrews is marketing director for flame retardants at Chemtura, a major supplier of BFRs, and the supplier of one of the broadest ranges of flame retardants of all types in the world. He sees growing opportunities for the company's BFR product line as law makers apply more stringency to flame retardancy in all sorts of products, but particularly in the electrical/electronics (E/E) sectors.

He cites work going on at the International Electrotechnical Commission (IEC) TC 108 standards committee to toughen up requirements for flame retardancy in TV sets and other IT equipment. The IEC is preparing a standard that will cover resistance of equipment to external fire sources, such as candles. Currently, many equipment suppliers only make their products resistant to fires that start inside the equipment. Exterior casings for TVs and computers sold in Europe do not have to be flame retardant. The US has its own regulations that call for casings to conform to UL 94 V-0, and as a result, plastics (mostly styrenics) containing BFRs are widely used. Every year in Europe, there are 325 fires for every million television sets, compared with just six in the United States.

On the other hand, European Union legislation could be pushing things in the opposite direction. The recently-enforced WEEE Directive, regulating the collection, reuse and recycling of post-consumer electrical and electronic equipment waste, says plastics containing BFRs must be removed from equipment and disposed of separately. And the Rolls Directive (Restriction of the Use of Certain Hazardous Substances) restricts the use of heavy metals such as lead, cadmium, chromium (IV) and mercury as well as polybrominated biphenyls (PBBs) and all polybrominated diphenylethers (PBDEs) apart from decaBDE--which has received a positive risk assessment--in electrical and electronic equipment.

Implementation of these directives is still in its infancy, so it is difficult to tell what effects they will have. However, the WEEE directive permits thermal recycling with energy recovery and does not restrict BFRs along this path. And with the cost of material recycling of such complicated consumer products being prohibitively high, it is likely that incineration will be the preferred route.

Andrews says that under Chemtura's 'Green is Better' programme, "if we develop a good FR product with a better environmental profile, we will move aggressively to replace less green products." He mentions Firemaster 550, a phosphorus-bromine product that has taken the place of pentabrominated diphenylether (pentaBDE) for use in flexible polyurethane foams. The US Environmental Protection Agency (EPA) declared Firemaster 550 to be "not persistent, bioaccumulative or toxic to aquatic organisms" after testing it.

Chemtura still makes PBDEs for other plastics, such as high-temperature nylons, and Andrews insists they have good environmental profiles. Nevertheless, it is working on replacements. Some new products will be announced at K 2007, but he will not be drawn on what they are, beyond saying they will be based on phosphorus-bromine chemistry.

Uncertainty

The message is similar from Albemarle. Earlier this year, it unveiled Saytex 102HP, a high-purity form of decabromodiphenylether. Vivien Kilian, Albemarle Europe's flame retardants product manager, said in May that there was still uncertainty as to whether the EU's exemption of decaBDE from a ban on PBDEs under the RollS directive referred to the 100 percent pure version, which is practically impossible to produce, or to commercially available products, which contain 2-3 percent of other diphenyl ethers. She says the new product, not yet fully commercialised, is 99.5 percent pure, and users should meet the norm, whatever its precise meaning turns out to be.

At the same time, the company is continuing development of brominated polystyrene FPs. It launched Saytex HP-3010 a few years ago, for use in high temperature nylons. Kilian says: "We are looking to see if it fits with other polymers too. We still believe in halogens, for us they are the best flame retardants you can get. If you look at all the risk assessments that have been carried out on decaBDE, there is no risk associated with it, it's the only flame retardant that has been so extensively researched, and yet we still have issues defending it."