POLYAMIDES | ADDITIVES
Performance of CAI’s low-loading MCA flame retardant systems in polyamide. ST-MCA-H enables UL-94 V-0 performance in unfilled PA6 and PA66 at approximately half the loading of conventional melamine cyanurate systems (left). Mechanical properties of representative formulations demonstrate strong structural performance at these lower additive levels (right). Source: CAI Performance Additives
improved, which enables effective char formation at lower loadings than conventional MCA grades, the company reported. “In unfilled PA6 and PA66 formulations, ST-MCA- H achieves UL-94 V-0 ratings at 0.8 mm, 1.6 mm, and 3.0 mm thicknesses at typical loadings of 5% in PA6 and 4% in PA66,” the company said. “Because the loading is roughly halved [compared to typical MCA], compounders benefit from better retention of mechanical properties, lower density, easier colour matching, and improved surface quality, while maintaining halogen-free flame-retardant performance. [The] lower dosage helps maintain toughness, reduce the risk of blooming or migra- tion, and improve overall compound competitive- ness in demanding electrical and electronic applications.” Momentive has introduced SFR100, a siloxane available as a liquid and also in masterbatch form, that can be used as an FR synergist with organic and inorganic FRs in HFFR formulations in engi- neering thermoplastics including PA and PC. As a synergist with a primary FR In polyamides, includ- ing PA66 as well as higher temperature polymers such as PA612, the additive helps reduce flamma- bility and improve properties such as impact resistance and elongation at break.
Thin-walled parts A relatively new polyamide copolymer from Invista aims to meet a need for compounds used in thin-walled, injection moulded parts, such as connectors and housings, that must meet flame
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retardancy and electrical safety requirements. The company introduced two PA66/6T copolymer products, CT1A with medium terephthalic acid (T) content and CT4A with higher T content, and has seen good reception of the new products as cost-effective alternatives to polythalamides (PPAs), which are often used in these applications, said John Buzinkai, Product Development Manager, at Invista. He explained that the PA66/6T copolymers have good flowability and can be processed at tempera- tures similar to PA66, whereas PPA requires higher processing temperatures and does not flow as easily. “We see a trend to thinner cross-sections and more intricate cavities, with a real emphasis on good flowability,” said Buzinkai. In glass-fibre-reinforced compounds with non-halogenated FR additives, the PA66/6T copolymer can be used to achieve UL 94 V-0 performance at lower FR levels compared to PA66. “For example, in a GF-reinforced non-halogenated PA66 formulation used in a thin (0.7 mm) section, you might need 18% FR to achieve V0 in PA66, but only 14% FR to achieve V0 in PA66/6T. The lower FR content is a cost saving and also can lead to better mechanical properties and less corrosion of the moulding equipment,” Buzinkai said. “We have also seen glow wire ignition temperatures over 775° C, and comparative tracking index over 600 V.” Colorants with higher thermal stability, up to 300°
C, are beneficial for polyamides to prevent any colour change. At K2025, Lanxess highlighted its Colortherm heat stable inorganic pigments.
� April 2026 | COMPOUNDING WORLD 33
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