Plastics That Can Handle The Heat

(source: September 2019 INJECTION WORLD)

High temperature thermoplastics are increasingly replacing metals in automotive, aerospace, electronics and domestic appliances. Peter Mapleston reports on developments in PA, PPA, PPS, PEEK and other polymers Injection moulders and specifiers may be forgiven for not knowing which way to turn when it comes to choosing thermoplastics with resistance to high temperatures. In recent years, portfolios of high temperature polyamides (most but not all of them polyphthalamides, PPAs), polyphenylene sulphides (PPS), polyaryletherketones (PAEKs, of which the most famous is polyetheretherketone, PEEK), and polyetherimide (PEI), have all grown substantially, as material suppliers work to cater for growing demand.

Interest in high-temperature-resistant thermoplastics (HTPs) is coming from all directions. That’s the view from Brett Weishalla, Senior Product Development Engineer at major compounder RTP Company in Winona, MN, USA. “While the manufacturers in the automotive, aerospace, oil and gas, electronics, consumer goods, and semi-conductor markets have been long-time users of HTPs, particular segments - such as electric vehicles or e-cigarettes - are quickly developing into market spaces of their own,” he says.

At Conventus Polymers, an up and coming specialty thermoplastics distributor and formulator based in Parsippany, NJ, USA, company president John Jorgensen says HTPs typically offer ancillary benefits in addition to temperature resistance, such as inherent flame resistance, excellent flame, smoke, and toxicity (FST) properties, superior chemical resistance, good creep resistance, very high purity, and many others. “HTPs continue to increase in popularity as options for metal replacement in many industries with critical applications, including automotive, oil and gas, healthcare, semi-conductor, electrical, fluid handling, membrane/filtration, food service, and aerospace to name a few,” Jorgensen says.BASF is among leading polymer producers innovating to respond to this increase in popularity.It has launched no fewer than three new families of PPAs – polyamides with extra high temperature resistance thanks in part to their semi-aromatic nature – since just before K2016, explaining that “this fundamental market challenge cannot be solved by a single material”. The company’s PPA portfolio, which comprises some 50 compounds, is now based on four polymers: Ultramid T KR, a PA6T/6, which BASF has been selling since the 1990s; Ultramid Advanced N, a PA9T unveiled at K2016; Ultramid Advanced T1000 (PA6T/6I) introduced at Fakuma 2018; and Ultramid Advanced T2000 (PA6T/66), which debuted at Chinaplas 2019.

At the launch of Ultramid Advanced T2000 in May, Abdullah Shaikh, head of the global PPA team at BASF, said the product “is the ideal solution for parts that require high, constant stiffness and strength over a broad temperature range in combination with resistance to heat and humidity as well as optional flame-retardant (FR) properties.” According to BASF, the latest PPA shows improved impact strength on a par with standard PA66 and a lower water uptake than standard aliphatic polyamides, resulting in high dimensional stability. Its high melting point (310°C) and heat deflection temperature of over 280°C (HDT-A) make it suitable for lead-free soldering without part deformation. Flowability is “significantly higher than that of other high-temperature polyamides without compromising flexibility or toughness”.Within the T2000 family, BASF has developed a special range of FR grades reinforced with 30% to 40% glass fibres and with UL 94 V-0 rating available for all colours. In addition, there are several grades with reinforcement levels ranging from 30% to 50% glass fibres and improved impact resistance, available both as uncoloured and laser-markable black. Different heat stabilisers are available.

Also working on PPAs is RadiciGroup High Performance Polymers, which has developed several grades under the Radilon Aestus brand. Once again, the materials are less affected by humidity than standard polyamides; they also have higher resistance to hydrolysis, as well of course as higher melting temperatures. The Radilon Aestus T range complements other products from RadiciGroup High Performance Polymers based on PA 6 and 66. The company’s marketing emphasis appears rather different from BASF’s. Global Marketing Manager Erico Spini cites applications for Radilon Aestus T1 RV 300 FC and Radilon Aestus T1 RV 400 FC in food-contact products suitable for use at temperatures of up to 270°C. Products aimed at hot water plumbing include Radilon Aestus T1 RV300 RKC, T1 RV 400 RKC, and T1 RV 450 RKC, while Aestus T1 RV330RG is suitable for components contact with automotive engine coolants.

Expanding options in PA9T

Last year, Kuraray expanded its Genestar PA9T E&E grade portfolio with flame-retardant (V-0) halogen-free 30% glass reinforced grades (see Injection World September 2018). This year, it is highlighting the fact that it is removing the last barriers for use of the grades in E&E applications, by finalising the necessary UL registrations, such as RTI values.“Since Genestar PA9T grades are unique in combining a good processability with JDEC MSL 1 blister resistance, CTI [Comparative Tracking Index] over 600 V and a high weld-line strength, these benefits can finally be experienced by design engineers in Europe,” says Wim Dennison, Market Development Specialist with Eval Europe, Kuraray’s subsidiary in Belgium. Dennison also points to a new “electro-friendly” 30% glass reinforced grade, G1300A-M42, which has improved toughness, developed to target more robust automotive connectors and parts in close proximity to electronic components. “When increased mechanical properties are prioritised over high flow as is normally desired for small E&E parts, this grade could be an exquisite fit,” he says.Compounder Akro-Plastic has expanded its product portfolio of PPAs with Akromid T9, which is also based on PA9T. It notes that PA9T absorbs less water than other PPAs, so its Tg is less affected after conditioning (ending up at 100°C, down from 120-125°C, whereas other PPAs can lose around 40°C).

“Polymer producers usually design grades to balance properties for general purpose use,” says Conventus Polymers’ John Jorgensen. “Higher competition has led PPA producers to differentiate by developing specialty grades. The availability of specialty grades allows engineers to select formulations that better serve their unique set of requirements. This often results in improved performance and/or capabilities for the next generation of existing applications, and the design of new products addressing spaces previously out of reach.”

RTP’s Weishalla says that although new PPAs have expanded the potential operating environments and applications for PPAs, the trade-off between performance and economics “is a delicate balance. There will still be plenty of room for the more economical conventional grades in most applications.”

(complete article at injectionworld.com)