THERMALLY CONDUCTIVE | COMPOUNDS
density of 1.5 g/cm3
) compared very favorably with
aluminum (thermal conductivity of 120 W/m·K, emissivity of 0.22 and density of 2.7 g/cm2
) in the
application. The software analysis showed that Lati’s graphite- based compound outperformed aluminum even at 35°C room temperature using the existing alu- minum part design. Lati and Protool then improved the design through filling simulations. Fins were added, which improved thermal performance and dropped residual temperature by 10°C. The part geometry, cooling system and feeding system design were then further optimised to achieve high dimensional stability and ease of assembly.
Cooperation matters The need for a high level of cooperation between all participants in a thermally conductive project is also highlighted by Christine Van Bellingen, Business Development Manager, Conductive Compounds at Netherlands-based Wittenburg Group’s compound- ing subsidiary Witcom Engineering Plastics. “There are market expectations for thermally conductive plastics but still barriers and question- ing before quick development,” she says. “The major questions we encounter are which thermal conductivity shall I target when replacing metal? Are standard plastics not enough? Which measure- ment method shall I use? Can I get enough mechanical properties despite the high filler loading? What is the best mould design to orient the conductivity?” The sustainability benefits available by replacing metal with lightweight polymer-based alternatives, and the associated reduction in carbon footprint, are certainly enough to drive interest, Van Bell- ingen explains. “The minor space available in automotive and the high weight of electric vehicles will push for new plastics developments to replace metallic parts, involving thermally conductive or EMI shielding thermoplastic compounds, for ECU housings, battery cooling or LED lighting.” However, Van Bellingen adds that realising a successful outcome requires project partners with the right resources and strong collaboration between all players. “From a material perspective, it is role of the specialty plastics compounder to wisely select the plastics and additives that offer the best overall properties, and to resolve the many open questions to reassure our partners on the benefits,” she says. “At Witcom, we have developed thermally conductive formulations that are electrically conduc- tive and others that are insulative. In housings for electronics, the material should remain electrically insulative and often be flame retardant on top, as
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Lati and Protool Plastics used detailed fill analysis to ensure the Hexagro LED light source — moulded in a Laticonther PA6 grade with thermal conductivity of 12 W/m·K in-plane — met required dimensional limits for easy assembly Image: Lati
well as reinforced, and easily processable.” Examples include Witcom PA6-342, which is a
reinforced, thermally conductive (1-2 W/m·K), electrically insulating, halogen free flame retardant (UL 94 V-0 at 1.6 mm) compound that is easily processable and suitable for dissipating heat in parts such as ECU housings and power tool cover. Witcom PA6-334 is a reinforced, thermally conduc- tive (6 W/m·K though-plane, 20 W/m·K in-plane), electrically conductive compound suitable for LED light heat sinks. Van Bellingen says Witcom already has a range
of products, and can develop new grades, custom- ised to industry and e-mobility needs. However, she also points out that thermally conductive polymer compounds are competing against more than just metal in EV thermal dissipation applica- tions, citing the example of battery cooling where alternatives — including gap fillers or liquid cooling — could be preferred.
CLICK ON THE LINKS FOR MORE INFORMATION: �
https://www.envalior.com �
https://www.fibrecoat.de �
https://www.plastformance.com/ �
https://www.sabic.com �
https://www.imerys.com �
https://www.eurotec-ep.com �
https://www.celanese.com �
https://lati.com �
https://www.protoolplast.com �
https://wittenburggroup.com/witcom/
September 2023 | COMPOUNDING WORLD 25
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