Environmental Project, 1141 – Deca-BDE and Alternatives in Electrical and Electronic Equipment

Deca-BDE and Alternatives in Electrical and Electronic Equipment

2 Applications of Deca-BDE

Polybrominated diphenyl ethers (PBDEs) are a group of aromatic brominated compounds in which one to ten hydrogens in the diphenyl oxide structure are replaced by bromine.

Three different PBDEs have been commercially available. They are referred to as penta-, octa- and decabromodiphenyl ether, but each product is, in fact, a mixture of brominated diphenyl ethers.

Decabromodiphenyl ether, or Deca-BDE, as indicated by the name, has ten bromine atoms attached to the diphenyl oxide structure, and a bromine content of 82-83%, making it a very efficient flame retardant.

The CAS No (chemical identification number) of decabromodiphenyl ether is 1163-19-5. The substance is also known as decabromodiphenyl oxide (DBDO) or bis(pentabromophenyl) ether.

Figure 2.1 Chemical structure of Deca-BDE (from [8])

Figure 2.1 Chemical structure of Deca-BDE (from [8])

Commercial Deca-BDE is marketed, among other names, as SAYTEX® 102E (Albemarle Corp.) [[8]], Great Lakes DE-83 RTM (Great Lakes Corp.) [[9]] and FR 1210 (ICL Industrial Products) [[10]].

The commercial Deca-BDE contains small impurities. In 1995, the US and European producers committed themselves to producing Deca-BDE with an average purity of 97% or better [[11]]. The remaining part have typically mainly been made up by nonabromodiphenyl ether (with nine bromine atoms) [17]. According to the European Union Risk Assessment Report – Bis(pentabromophenyl) ether, "The actual composition of the products from different producers/suppliers is regarded as confidential information." [16] The EU Risk Assessment applies to the commercial Deca-BDE [16].

Deca-BDE is the most widely used of the PBDEs, with a global demand of about 56,100 tonnes in 2001 (see Table 2.1) and 56,418 tonnes in 2003 [18], according to the manufacturers of FRs.

As indicated in Table 2.1, the U.S. market for Deca-BDE is significantly larger than the European market. A recent US study of alternatives to Deca-BDE prepared by the Lowell Center for Sustainable Production [[12]] reported that roughly 80% of Deca-BDE use in the U.S. is thought to be in electronic enclosures (housings, casings), with the vast majority used in the back and front plates of television sets. The majority of TV-set enclosures in the U.S. are, according to the study, made from HIPS with Deca-BDE, whereas enclosures in Europe are primarily made either without FRs or with other FRs.

Table 2.1 Market demand for PBDEs and two other major brominated flame retardants, by region, in 2001 (tonnes) [ 18]

Metric tons	Americas	Europe	Asia	Rest of the World	Total
TBBPA	18,000	11,600	89,400	600	119,700
HBCD	2,800	9,500	3,900	500	16,700
Deca-BDE (DBDPO)	24,500	7,600	23,000	1,050	56,100
Octa-BDE (OBDPO)	1,500	610	1,500	180	3,790
Penta-BDE (PBDPO)	7,100	150	150	100	7,500
TOTAL	53,900	29,460	117,950	2,430	203,790

TBBPA: Tetrabromobisphenol A; HBCD: Hexabromocyclododecane

Combining the information in Table 2.1 and Table 2.2, it can be estimated that Deca-BDE accounted for about 2% of the total European FR market for all applications in 2001.

According to the recent progress report on "The Voluntary Emissions Control Action Programme for the brominated flame retardant Deca-BDE", the textile and plastics industries in the UK, France, Germany, Italy, Belgium and the Netherlands are responsible for more than 95% of the Deca-BDE consumption in the EU [[13]].

Table 2.2 European market for flame retardants, 2001 (based on [[14]])

Flame retardant	Market supply
Flame retardant	Tonnes	%
Brominated FR	51,000	11,8
Chlorinated phosphates	42,000	9,1
Non halogenated phosphorous based	172,000	9,7
Aluminium trihydroxide	20,000	40,0
Magnesium dihydroxide	9,000	4,7
Melamine and its salts	25,000	2,1
Antimony trioxide	71,000	5,9
Cloroparaffins	2,000	16.5
Borates	51,000	0,4
Overall total	430,000	100

Deca-BDE is a flame retardant with a wide application spectrum in plastic resins and textiles. It is an additive flame retardant, which means that it does not chemically react with the plastic resin. Deca-BDE is always used in conjunction with antimony trioxide (ATO), which acts as a synergist.

Current applications of Deca-BDE, according to information from the Bromine Science and Environmental Forum (BSEF), are shown in Table 2.3

Table 2.3 Applications of Deca-BDE, according to the Bromine Science and Environmental Forum [[15]]

Table 2.3 Applications of Deca-BDE, according to the Bromine Science and Environmental Forum [[15]]

Note: Nylon = polyamide = PA

According to the European Union Risk Assessment Report – Bis(pentabromophenyl) ether, the main application for Deca-BDE is in HIPS for TV-set back plates: "Industry information indicates that decabromodiphenyl ether is used at loadings of 10-15% weight in polymers and is always used in conjunction with antimony trioxide. The major application for decabromodiphenyl ether is in high impact polystyrene (HIPS) which is used in the television industry for cabinet backs. It is also used in a large number of other polymers with end-uses in electrical and electronic equipment (e.g. computers, connectors, electrical boxes, wire and cable etc.). Examples include polypropylene (for electronics), acetate copolymers (EVA (ethylene-vinyl acetate) and other ethylene copolymers for wire and cable), EPDM (ethylene-propylene-diene terpolymer) and thermoplastic elastomers (for wire and cable) and polyester resins (for electronics). Other minor uses include styrenic rubbers, polycarbonates, polyamides and terephthalates, and small amounts are also reported to be used in hotmelt adhesives" [[16]]

The most recent breakdown of global consumption of Deca-BDE among various applications in an official report dates back to the early 1990's. At that time the global consumption of 30,000 tonnes of Deca-BDE was broken down as follows: 30% polystyrene (HIPS), 20% thermoplastic polyesters (PBT, PET), 15% polyamide (PA), 10% styrenic rubber (SBR), 5% polycarbonate (PC), 5% polypropylene (PP) and 15% other polymer applications [[17]].

This consumption pattern is most probably significantly different today, but no comprehensive updated breakdown of consumption has been identified.

Leisewitz et al. (2001) reports that Albemarle Corp. declares that 85% of Deca-BDE is used in HIPS for casings of EE appliances [22].

According to a presentation by Munro et al., of Great Lakes Chemical Corp., at ADDCON 2004, Deca-BDE more recently represents about 10% of the FR consumption for thermoplastic polyesters used in EEE, corresponding to 1,500 tonnes; and 6% of the FR consumption for polyamides used in EEE, corresponding to 840 tonnes [56]. Assuming the global consumption of Deca-BDE in 2003 was 56,418 [[18]] tonnes, it may be estimated that consumption of Deca-BDE for polyesters and polyamide in EEE applications represents about 2.7% and 1.5%, respectively, of the total global consumption of Deca-BDE. One reason for this substantial reduction – compared to the early 1990s - in the use of Deca-BDE for polyesters and polyamide may be that other brominated flame retardants have taken over the majority of the FR market for these resins, as discussed in section 3.3.

The European Brominated Flame Retardant Industry Panel, in its comments to the European Commission's Stakeholder Consultation, emphasised in particular the difficulties of finding alternatives for three resin types with which Deca-BDE is used: "Alternatives are not always available: In certain plastic resins like HIPS, ABS, and PBT, there are currently no cost-effective alternative flame retardants which can provide good flame retardancy and good mechanical properties." [[19]]

The advantages of Deca-BDE emphasised by manufacturers are high bromine content, good thermal stability and cost effectiveness, as noted in the following quotations:

Albemarle Corp.: "SAYTEX 102E flame retardant is a prime candidate for most applications due to its overall performance and cost effectiveness. Its good thermal stability makes it a candidate for applications in which resistance to high temperature is required. Because of its high bromine content SAYTEX 102E flame retardant is highly effective in achieving desired levels of flame retardancy.” [8]

ICL Industrial Products: "Its high bromine content coupled with its exceptional thermal stability makes it the material of choice for a large variety of applications.” [10]

Great Lakes: "Great Lakes DE-83R™ is a high purity fully brominated aromatic flame retardant with excellent thermal stability. It offers outstanding cost/performance." [[20]]

It should be noted that the thermal stability of Deca-BDE seems to be shared with other brominated flame retardants as shown in the following chapter, in which Deca-BDE is compared to a number of alternatives for different applications.