MATERIALS | HIGH-TEMPERATURE PLASTICS


Several polyamide suppliers are taking a PHOTO: DSM


Above: Small electronic components like these USB Type-C connectors are a battleground for suppliers of rival high-heat materials such as LCPs and PA4T and 9T polyphthalamides


400 V. It maintains this high performance for twice as long as alternative materials, most of which have CTIs under 400 V. In tests on connectors produced in LCP, the connector pins fail after nine drops, causing a short circuit; neither PA 46 [DSM’s Stanyl, also used for electronics] nor PA 4T fails at all.” The debate will doubtless go on. Most polyamides aimed at high-temperature


application are PPAs – but not all of them. Suppliers are also squeezing as much as they can out of “standard” polyamides 6 and 66 (witness Ascend Performance Materials’s Vydyne HT series for exam- ple, and Solvay Performance Plastics’ Technyl Red J, designed for turbocharger systems running at continuous temperatures up to 220°C – see Injection World May 2018). Last year, Lanxess commercialised its latest heat


stabilisation system for PA66 variants of its Dure- than family, XTS2 (Xtreme Temperature Stabilisa- tion). It says the system increases the heat aging durability of PA66 “so much that they reach into the heat deflection temperature range.” According to Thomas Linder, a Durethan material development expert in the High Performance Materials business unit at the company, “thanks to the new iron-free thermo-stabilisation, our PA66 variants can with- stand temperatures of up 230°C in the long-term.” First product from the XTS2 product range is


Right: Kitchen utensils are one market for Radici’s high-heat materials


Durethan AKV35XTS2, containing 35% glass fibre. Future variants will have different levels of rein- forcement.


In long-term hot air aging tests, the supplier


says, even after 3,000 hours of storage at 230°C, the reduction in tensile stress at break and elastic modulus “is barely measurable”. Durethan AKV35XTS2 is mainly targeted at automobile engine applications such as air intake manifolds with integrated charge air coolers or air pipes located in the vicinity of the turbocharger. Established XTS1 and XTS3 stabilisation systems from Lanxess enable continuous use of Durethan at around 200°C.


36 INJECTION WORLD | September 2018 www.injectionworld.com


twin-pronged approach to high-heat applications, offering polyphenylene sulphides (PPS) to comple- ment PPAs and/or other versions of PAs with enhanced thermal resistance. RadiciGroup is one of these, with its Raditeck P PPS and Radilon Aestus PPA. But first off, Marketing & Application Develop- ment Director Erico Spini points to Torzen Mara- thon, its modified PA66 (originally developed by Invista, whose engineering polymer business Radici bought two years ago), which can withstand continuous-use temperatures of up to 190°C. This, together with very good flow that translates into smooth part surfaces, makes the material very suitable for all components where seals are required (such as air intake manifolds and oil modules). In the case of applications with continu- ous exposure up to 210°C and in contact with hot air, the Radilon HHR family (also PA66-based, but a Radici original) are the materials of choice, the company says.


Hot in the kitchen Discussing Radici’s Radilon Aestus PPA (based on PA6T), Spini highlights the potential of special grades in two quite diverse markets: kitchen tools and electronics. The company has developed grades with very low levels of extractables for kitchen tools that need to withstand high temperatures (the FC – Food Contact – family, typically with 35% glass fibre). It also offers grades for electronic components that withstand reflow soldering temperatures, and which are also suitable for “high power” applications traditionally served by thermosets. As to Raditeck P, Spini says PPS is a very good choice where dimensional stability is critical, owing to the fact that PPS does not have the water absorption problems associated with many polyamides. Its inherent flame retardance is another important plus point.


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