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Arbejdsrapport, 27/2001 Analysis for Bromine in Electronic PartsContents2 Bromine content in plastics & electronic parts 3 Results of material analyses SummaryIn 8 out of 16 purchased household appliances plastic parts containing brominated flame retardants were found. The bromine content of the various types of plastics differs considerably, varying from 0.02 weight% to 9.6 weight%. The detection limit for bromine and antimony is 0.01 weight%. The 3 fan heaters analysed showed bromine and antimony in all the plastic parts used for the constructions. In the other appliances it was small units with a content of flame retardants. In most cases it was electric components or units close to hot surfaces. 1 Background and PurposeBrominated flame retardants are used as fire retardants in a large number of different products such as textiles, computer screens and household appliances. The brominated flame retardants primarily contain carbon, hydrogen and bromine. Some of the substances are concentrated in the food chain and are suspected of causing cancer and hormone disturbances. The analysis shows the content of bromine and antimony in the products. However, it has not been examined which fire retardants the substances come from. The National Agency of Environmental Protection has requested an analysis of a number of electronic parts and household appliances for content of brominated flame retardants. Mr. Jacob Maag, Cowi, has assisted in choosing the appliances on behalf of the National Agency of Environmental Protection. The appliances chosen were purchased by the Danish Technological Institute, Chemical Technology, Aarhus, where the analysis for content of bromine was carried out by X-ray technique. Prior to this analysis Mr. Nils Nilsson, Danish Technological Institute, Environmental and Waste Technology, had prepared a memo on bromine in electronic parts, concluding that a considerable content of bromine in plastics from household appliances came from components added to the plastics with the aim of having a fire retarding effect. 2 Bromine Content in Plastics and Electronic PartsPrior to the practical analysis for content of bromine in the purchased appliances, an analysis of brominated compounds in plastics and electronic parts was carried out. The analysis was based on the collected knowledge on plastics at the Danish Technological Institute and on literature studies. The conclusion of this analysis was that brominated compounds were merely added to the plastics to reduce the combustibility of the plastics. The brominated compounds can be divided into two types: 1) Compounds added to the plastics and 2) Compounds built into the plastic polymer. The analysis is described in encl. C. 3 Results of Material AnalysesThe appliances analysed comprise two irons, two coffee machines, three fan heaters, two deep fryers, two boiling pots, two food processors, two toasters and one heating blanket. A list of the appliances analysed appears from encl. B. As can be seen from the table of results, individual parts of the appliances have been analysed for content of bromine and antimony. In about half of the appliances bromine was found in the plastic materials. Encl. A, pages 1-16, show photos of all appliances with pictures of separated parts and indication of some of the elements. As could be expected, brominated flame retardants were found in the parts of the appliances with the highest temperatures. The table overleaf states the results of the analyses. The detection limit for bromine and antimony is 0.01 weight%. Table of results
4 Analytical MethodsThe chosen household appliances were separated and the materials selected from outer cabinets, printed circuit boards, where available, switches and other electric parts as well as plastics with direct contact to heating surfaces. By the first screening of the selected parts some large and small plastic components containing bromine and antimony were found. For this screening a Philips EDAX PV9100/9500 energy dispersive X-ray fluorescence spectrofotometer was used. By this relatively fast screening it was possible to sort out plastic parts con-taining brominated flame retardants for further quantitative analysis by the use of elementary analysis and analysis on plane surfaces with Philips PV2400 wavelength dispersive X-ray fluorescence spectrofotometer. On the basis of these results the EDAX equipment was calibrated. In this way it became possible to carry out a quantitative analysis for bromine and antimony of samples not being shaped as plane surfaces. As a consequence of the shape of the samples and for instance content of calcium (Ca) in the plastics, overlapping the analysis for antimony by EDAX, there is a deviation in the results for antimony of up to 25% rel. The accuracy of the bromine value is 10-15% rel. Encl. ADe følgende sider, der udgør bilag A, viser fotos af de undersøgte produkter. Encl. BList of purchased products
Encl. CMemo on the Project: Analysis for Bromine in Electronic PartsPrepared by Nils H. Nilsson, Environmental and Waste Technology, Danish Technological Institute, for Ivan Christensen, Chemical Technology, Danish Technological Institute Introduction The primary aim of the project was to determine to what extent brominated flame retardants are found in household appliances on the Danish market. The present memo assesses the possibility of other bromine compounds than brominated flame retardants being present in the plastic parts of the household appliances than the brominated additives added to the plastics to have a fire retardant effect. Overall conclusion On the basis of the Institute’s collected knowledge on plastic materials and a brief literary survey of additives for plastics it seems to be extremely unlikely that other brominated compounds have been added to the plastics of the household appliances than the bromine-based flame retardants and under no circumstances in concentrations of an order corresponding to that of the fire retardants. In the first place, the bromine compounds are rather expensive as compared to the corresponding chlorinated compounds, secondly, no examples of commercially offered or otherwise used additives in the form of bromine compounds for plastics other than the brominated flame retardants have been found in the handbooks and literature studied. The reason why the bromine-based flame retardants are used to such an extent is that by addition of a comparatively small amount of the bromine-based flame retardants a fire retardant effect is achieved so that the plastics can fulfil the so-called UL-requirements or other standardized fire classifications. However, it must be added that the bromine-based flame retardants in large concentrations may function as plasticizers in the plastics if the solubility parameters make it possible. Otherwise the flame retardant must be regarded as a filler. Furthermore, it should be mentioned that in principle it is possible to build bromine-substituted monomers into the plastic polymer with the same purpose, viz. to reduce the combustibility of the plastics. It depends entirely on the type of plastics if this is a realistic possibility. Another possibility is to brominate the polymer after the polymerization process. This is hardly very realistic. Reactive flame retardants are primarily used in connection with thermoset, for instance polyurethane polymers and epoxy polymers. These plastic types are not assessed to be used in household appliances to any appreciable extent. However, thermoplastic polyurethane types may form part of household appliances. It should be added that reference1 states the possibility of building hologen-containing monomers into ABS (acrylonitril-butadiene-styrene plastics). Both chlorine and bromine belong to the halogens. Basis of assessment The references state the literature that has been used as the basis for the conclusion. At the same time it can be mentioned that through almost 20 years’ work with the chemistry, physics and technology of plastics the undersigned has not come across literature dealing with other bromine compounds added to plastics in relation to the plastic types used commercially in electric and electronic appliances, including household appliances, than bromine compounds with fire retardant properties. Household appliances Household appliances comprise first and foremost electric articles such as vacuum cleaners, hair dryers, curling irons, toasters, coffee machines, hot water boilers, mixers, blenders and other electric types of mixing equipment as well as shavers and massage apparatuses. Types of plastics used for household appliances A number of different types of plastics are used in electric household appliances. Whether the plastics is fire retardant or not depends on the location of the plastics in relation to the electric parts of the appliance, how high and critical the temperature is at maximum load, and the legislative requirements applying to electric articles /electronics. The most frequently used plastic types for household appliances are polyethylene, polypropylene, acrylonitril butadiene styrene (ABS), polyester types (PBT, PET), polycarbonate (PC), polyamides (PA 6, PA 66), polysulfone (PSU), polyphenylene oxide (PPO), polyether sulfone (PES) and phenol plastics. The last type is a thermoset as compared to the rest which are all thermoplastic types. The choice of plastic type depends on the kind of mechanical properties essential to the perfect functioning of the household appliance, the temperature to which it is exposed, electric properties (insulating, antistatic), possible demands in relation to food contact, etc. Fibres or fillers may often be added to the plastics. These may both contribute to strengthening the plastics, but also to reducing the combustibility of the plastics. Polyethylene (HDPE) and polypropylene (PP) are the less expensive of the plastic types. However, they are also those of the above-mentioned plastic types with the lowest melting interval/softening point, and therefore, there is a limit to the temperature to which they can be exposed. PBT and PET are much used in electric household appliances, among other things because of their high softening temperature and a relatively favourable price of the raw material. Fire retardants There are brominated fire retardants reacting with the plastics and therefore chemically bound in the plastics as well as fire retardants not chemically bound. Antimony trioxide, which appears on the National Agency of Environmental Protection’s list of undesired substances, is often used together with brominated flame retardants as there is a synergistic effect. The reactive types of brominated flame retardants are used in the thermoset types unsaturated polyester, polyurethane and epoxy. These plastic types are not considered of great use in household appliances. However, epoxy is applied for printed circuit boards. The table overleaf shows examples of the concentrations of flame retardants used in the different types of thermoplastics in order to be able to fulfil the UL 94 fire klassification (UL = Underwriters’ Laboratories). The informa- tion comes from reference 7. Owing to their chemical lay-up and very high melting temperature, the polysulfone types have low ignition properties and flame spread in the case of fire. Therefore, there is little or no need for adding flame retardants to these types. Concentration of flame retardants in thermoplastic types
flame retardant is used. Thus, the quantity of brominated flame retardant can be limited, reducing the risk of changing the mechanical properties of the plastics in a negative direction. Many of the plastic types are also available with glass fibre reinforcement or addition of small glass balls, which enables a change of the rigidity of the material and reduces the quantity of plastics in the construction, making it less expensive. References
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