additives | Flame retardants
Fire performance of various PA6 compounds containing MCA’s halogen-free PPMT
Polyamide 6* (%) Glass fibres (%)
Exolit OP 1230** (%) PPM Triazine HF*** (%)
Melamine polyphosphate**** (%) Additives (%)
Average burning time (s) UL 94 (1.6 mm)
54.5 25 15 5 0
0.5 3
V-0
*Ultramid B3S (BASF); **Clariant; *** MCA; ****Melapur 200 (BASF); n.c: no classification Source: MCA Technologies
you get crosslinking to form a sort of glass wall around the part,” he says. “In recent years, many companies have come out with silicone based flame retardant nanoclays. They are very good, but they are particles, and this gives them limited mobility, limited capability. In a fire, they form a sort of shield but it is made out of blobs with gaps between them. Our product is more of a gel, and this enables it to form more of a continuous layer.” Polymer Dynamix sells Dynasil FR to compounders
in masterbatch form, offering it with various carriers. Mehta says his company has taken products that cannot normally pass fire standards and achieved pass results by adding Dynasil. “In the US, for example, there is the wire and cable VW-1 (Vertical Wire) test, which you cannot pass consistently with a metal hydrate FR technology. But it will pass with Dynasil. In Europe, in the vertical cable tray test covered by the EU Construc- tion Products Regulations (CPR), we can get much higher ratings.” Polymer Dynamix has learnt over the last year or so
how to put Dynasil into phosphorus-based systems, says Mehta. He claims it can be used with flame retardants such as Clariant’s Exolit OP aluminium phosphinate-based product, broadening scope into polymer systems beyond polyamides and thermoplastic polyesters. Clariant itself already offers Exolit OP grades with various synergists, the most recent additions being the 1400 grade, which can be used with high temperature polyamides, and 1260 grade for reinforced PBTs.
Halogen-free PPMT New polymeric PPM Triazine (PPMT) synergists from MCA Technologies work with a wide range of flame retardants. Company CEO Bansi Kaul says existing PPMTs have a halogen-containing end-group and are used mainly for intumescent systems in combination with ammonium polyphosphate (APP) for polyolefins.
24 COMPOUNDING WORLD | December 2016
54.6 25 10 10 0
0.5 14
V-0/V-1
59.7 25
7.5 7.5 0
0.5 21
V-1/V-2
54.6 25 0 0
20
0.5 32
n.c.
But many intumescent systems based on such PPMTs are not suitable for applications requiring high water resistance, he says. MCA’s new PPMT is halogen-free. “Its higher C and
N content gives better char/residue formation,” Kaul says. “Potential applications go far beyond classical acid-induced intumescence of charring.” In fact, he says the new PPMTs have been shown to
be effective synergists for both inorganic and phospho- rus flame retardants (including ATH and MDH), metal carbonates such as huntite and hydromagnesite, ammonium poly phosphates (APP), and phosphinates. The PPMT synergy mechanism is said to be generation of a resistant, ceramic residue layer (with inorganic FRs) and the formation of high-temperature resistant phosphorus oxynitrides (PON) as fire barriers. The non-ionic nature of PPMT contributes to durability and can improve polymer characteristics such as electrical insulation. This can be further improved by siloxane coating of the PPMT-FR blends. Applications include EVA, polypropylene, polyesters and polyamides.
Performance gains In a presentation earlier this year at the AMI Cables 2016 conference, Kaul detailed how the new PPMT performs in various systems. In a cone calorimetry test at a high heat flux of 50 kW/m², FR composites with MCA’s PPMT and inorganic filler FRs “undergo only low/ slow burning due to immediate char formation by the so-called ‘self-immolation’ principle, as evidenced by rather short times to ignition but very low peak heat release rate, right from the very beginning,” he said. He added that combinations with huntite/hydromagnesite far exceed the performance of combinations with ATH. Kaul also discussed combinations with metal phosphinates. These normally need to be combined with a nitrogen synergist for proper efficacy, he said, and this is most typically melamine polyphosphate. “MCA PPM Triazine HF is particularly recommended to be used in place of or in combination with melamine polyphosphate to resolve the issues of corrosion, resistivity/conductivity (electrical properties), reactions with the polymer itself, hydrolytic instability, water pick-up and longevity, and last but not least the weight reduction,” he said. Kaul added that MCA PPMTs are suitable as
synergists for halogen-containing flame retardants, “on one hand to reduce their loading and on the other hand to partially or totally replace antimony oxides.” Paxymer in Sweden has been developing flame
retardants specifically for polyolefins over the last six years. “We set out from the beginning to deal with smoke and smoke toxicity, flame spread, and peak
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