ADDITIVES | FLAME RETARDANTS
Kraiburg develops FR TPEs for PA bonding
Germany-headquartered TPE specialist Kraiburg TPE has devel- oped a custom-engineered halogen-free flame-retarded TPE range that offers good adhesion to PA, making it possible to produce hard/soft components for demand- ing E&E applications. More than a dozen different PA compounds with UL94 V-2 and V-0 classification were tested during the development of the materials, with the final focus on HFFR V-0 types. Adhesion testing showed widely varying results, depending on the
Dirk Butschkau at Kraiburg TPE. “Along with the formulation of the polyamide, the flame retard- ant’s temperature sensitivity is a major challenge. In multi-compo- nent applications, non-flame retardant TPEs are frequently processed at temperatures of 240 °C to achieve optimal adhesion,” she says. The newly developed flame-
polyamide formulation and the PA/ TPE combination. “The essential factor here is the modification of polyamides with appropriate flame retardants and additives,” say Martina Hetterich and
has a marked tendency to drip during combustion, but addition of the new additive suppresses dripping and helps the material achieve a V-0 rating at 1.6 mm. Cone calorimetry testing shows smoke generation to be lower than an existing (but unidentified) commercial flame retarded TPU. Adeka adds that ADK Stab FP-2600U can
provide flame retardancy at least equivalent to that obtainable with established grades of the ADK Stab FP-2000 series, but at lower addition rates. This has the additional advantage of a reduced negative effect on mechanical properties. Evonik reports new developments with its
synergistic OMS (organo-modified siloxane) technol- ogy, which can be applied to various flame retard- ants. It says its Tegopren 6879 and Tegomer H-Si 6441P can be used in glass reinforced polyamide and PBT thermoplastic polyester compounds intended for E&E applications, including electric vehicles. Tegopren 6879 is a liquid used for surface
treatment of inorganic additives such as MDH and ATH, making them easier to disperse in thermo- plastic formulations. Evonik says Tegopren 6879 makes the particle surfaces more hydrophobic, so that water uptake is reduced by up to 50%. This yields higher CTI values – obviously important for E&E applications. With compounds containing organic flame retardants, no whitening occurs in the water pelletising bath. Tegomer H-Si 6441 P is a polyester modified siloxane delivered in pellet form. It is said to have excellent compatibility in thermoplastic and thermoset resins. Kathrin Lehmann, Head of Innovation Manage-
ment Polymers, Interface & Performance, also highlights newly-acquired technology that she says brings much more flexibility to the FR market.
48 COMPOUNDING WORLD | December 2018
retardant TPE materials are said to provide optimal adhesion when processed at a relatively low melt temperature of 190°C. �
www.kraiburg-tpe.com
Evonik can now produce open-cell foams capable of absorbing up to 70% of liquid additives, includ- ing phosphorus-based additives and also some plasticisers. Lehmann says this provides a new opportunity for compounders who cannot (or do not want to) directly handle liquids. Evonik has also just announced that it plans to
market Visiomer Hema-P 70M 2-hydroxyethyl methacrylate phosphate as a flame retardant (and an anti-corrosion agent). Until now, this monomer has been mainly used as an adhesion promoter. Evonik says that, because is serves as a reactive diluent or as a co-monomer bonded within the polymer backbone, it does not migrate. Visiomer Hema-P 70M further improves flame retardancy in combination with non-polymerisable flame retardants. It is a low-viscosity product containing 30% methyl methacrylate. Its low colour index suits it well to optical applications in acrylate and methacrylate systems.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.pinfa.eu �
www.clariant.com �
www.frxpolymers.com �
www.lbf.fraunhofer.de/en �
www.techmerpm.com �
http://en.magminerals.ru/ �
www.europiren.com �
www.icl-group.com/flame-retardants/ �
www.quarzwerke.com �
www.byk.com/en �
www.appliedminerals.com �
www.paxymer.se �
www.adeka.co.jp/en/ �
www.evonik.com
www.compoundingworld.com
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