MATERIALS | FLAME RETARDANTS
delaying dripping in thermoplastics. Addition levels in the range of 0.5-4wt% of the additive batch can reduce the total amount of flame retardant additive significantly, it claims. For a standard PP copolymer, it says up to 7wt% can be added while retaining the UL94 V-0 rating in a given formulation. According to Paxymer CTO and inventor Dr
Figure 3: PP moulding compound containing Saytex 8010 retain its mechanical and physical properties after recycling loops Source: Albemarle
Swaraj Paul, the company has been placing considerable focus on deepening its analytical framework for formulation guidance on zero halogen formulations. “We combine analysis of thermal properties in the condense phase as well as gas phase composition with analysis of the char in a novel way to compare between materials. This gives us a very powerful qualitative tool for comparing between formulations,” he says.
Figure 4: Comparison of notched Izod impact properties of various flame-retarded ABS compounds containing Albermarle’s Satex Alero flame retardant), TTBPT (tris-tribromophenoxytriazine), TBBPA (tetrabromobisphenol-A), and a brominated epoxy oligomer (BEO-2) Source: Albemarle
retardancy and smoke reduction behaviour expected of ATH. Austria’s Kärntner Montanindustrie (KMI) has a
strong focus on micronised minerals with special particle shapes, more specifically with acicular, platy, or porous structures. It says that efforts to eliminate halogen in flame retardant formulations has revived interest in functional minerals in this application area, adding that high aspect ratio minerals such as mica and wollastonite can improve mechanical properties and dropping behaviour and support char formation. Flame retardant formulations often benefit from the addition of effective synergists. Sweden-based Paxymer offers a growing selection of patented synergists for use with phosphorus and nitrogen- based HFFR flame retardants, expanding its offering from polyolefins into a wider range of plastics over the past year. These include PA, ABS, PC/ABS and PC. Managing Director Amit Paul says the company is working with customers to improve the performance of formulations both from fire and mechanical point of view, as well as reducing cost. Paxymer’s technology involves the use of
acrylate functional polymers to propogate cross linking in the backbone. It works to improve char both density and flexibility, improving barrier properties as well as eliminating or significantly
32 COMPOUNDING WORLD | December 2021
Brominated developments Interest in halogen-free flame retardants is certainly growing but brominated flame retardants still play a major role in the plastics industry and suppliers of brominated products are standing their ground, both working on solutions to mitigate environmen- tal concerns while challenging the thinking behind some of them. Albemarle, for example, says it is committed to providing trusted brominated flame retardants (BFRs). “As we focus on providing exceptional fire safety solutions, sustainability is the cornerstone for our strategy,” says Matt Von Holle, Vice President of Fire Safety Solutions at the company. “Albemarle’s extensive research shows that its
BFRs are safe to use as additive and reactive components in plastics. Further, our Saytex brand- ed products, including 8010, BT-93, HP-3010 and HP-7010, can be recycled and contribute to the circular economy,” he says. Von Holle cites recent work with Saytex 8010 in
polypropylene (presented at Compounding World publisher AMI’s Fire Resistance in Plastics confer- ence in Dusseldorf, Germany, at the beginning of December), which showed little change in physical and mechanical properties while retaining flame retardancy (UL 94 V-0) after six moulding cycles (Figure 3). “These are large, thermally stable products that give stellar performance without sacrificing HS&E principles,” he says. Saytex Alero is claimed to offer excellent
recycling performance in HIPS and is highly compatible in other styrenics such as ABS. Com- pared to other melt-blendable FRs, Albemarle says it shows improved mechanical properties, includ- ing Izod impact (Figure 4). The grade has only a marginal effect on flow properties of ABS.
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