MATERIALS | FLAME RETARDANTS
Figure 5: Mechanical properties of three UL94 V-0 at 0.8mm PBT compounds containing different flame retardant systems
Izod notched impact, J/m Tensile strength, MPa Elongation at break, % Modulus, MPa
Source: ICL
Albemarle is currently exploring its performance in other polymers, including polyolefins. “We believe BFRs will have an increasing role to play particularly in high-growth areas such as EVs and 5G telecommunications,” says Von Holle. ICL says it has invested significant resources to confirm its flame retardant portfolio meets the challenges posed by new applications in EVs, most importantly in the power train, motor, power inverter and charging system, where extensive use is made of polyamides and thermoplastic polyes- ters. Its extensive application testing confirmed ICL brominated polymers exhibit outstanding results for critical parameters, says Technical Marketing Support Manager Marc Leifer. “ICL’s brominated polystyrene polymer (FR-
803P), brominated polyacrylate polymer (FR-1025) and high molecular weight brominated epoxy (F-2400, F-3100) performances surpasses those of non-halogen flame retardants,” he says. “This is especially true when it comes to high temperature polyamides, such as PA10T and PA6/66T.” Leifer says that polyamide FR compounds using
brominated polymers can cost up to 50% less than halogen-free compounds (containing diethyl- phosphinate, DEPAL) with the same V-0 rating. They can also provide higher Glow Wire Ignition Temperatures. In high-temperature stability tests on 30% glass
fibre reinforced PBT rated V-0 at 0.8mm, he says its FR-1025 achieved an HDT (Heat Deflection Temperature) result greater than 206°C, while an HFFR option was less than 205°C. At the same time, melt flow tests indicated thermal decomposition and depolymerisation in the compound containing the HFFR, Leifer says. Tests on various mechanical properties of the
PBT compounds at ambient temperature also produced superior results for both FR-1025 and FR-803P, compared with the compound containing DEPAL (Figure 5). Hydrolytic stability was also said to be better. According to Tom Griffiths, REACH Manager at the International Antimony Association (i2a), it is
34 COMPOUNDING WORLD | December 2021
important to consider the full safety and environ- mental picture when reviewing any flame retardant component. Antimony trioxide (ATO) is a useful synergist in flame retardants in EVs, particularly halogenated types, he says, as it can help reduce weight. “REACH has the potential to have a significant impact on the use of all types of FR in the EU. However, when reviewing any potential restrictions of antimony-containing FRs it is important that the focus is not just on the chemical/ hazard aspect but also on the impact on climate or circularity any restriction may have.”
Recycling BFRs Among the criticisms of brominated flame retardants are recyclability and the potential for legacy BFRs to leak into the environment. When it comes to polystyrene foams containing BFRs used for building insulation, this issue is being tackled head-on by the PolyStyreneLoop (PSL) cooperative. It was founded four years ago with the aim of developing a sustain- able solution for treating PS foam waste arising from building demolitions containing HBCD (hexabromo- cyclododecane), which is classified as a persistent organic pollutant (POP). ICL, which produces various flame retardants including BFRs, was one of the initiators of the project. It now involves more than 70 organisations across Europe. One of PSL’s directors is Lein Tange, who is also Director of Sustainability at ICL-IP Europe. The PSL cooperative has built a demonstration
plant that removes HBCD from used foam at Terneuzen in the Netherlands. It incorporates a solvent-based polystyrene purification and dissolu- tion process called CreaSolv and it started up in September. The CreaSolv process was codeveloped by German company CreaCycle and Fraunhofer Institute IVV. Tange says the plant will demonstrate the economic and technical feasibility of recycling PS-foam demolition waste containing HBCD. The process purifies PS to a level allowing it to be used to make new X-EPS and XPS foam. Separated HBCD is treated in a Bromine Recovery Unit (BRU)
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PBT 30%GF + FR-803P 63.1
105.1 2.0
10,735
PBT 30%GF + FR-1025 73.9
109.2 2.5
11,800
PBT 30%GF + DEPAL 50.4 61.4 1.3
11,00
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