AUTOMOTIVE | COMPOUNDS FOR EVs
compounds. The challenge is to keep performance at lower thickness and at acceptable cost. At Witcom, we have developed cost-effective EMI solutions to shield over various frequencies, making the switch from metal to functionalised plastics more attractive to the automotive industry. Final parts include sensors and housings,” she says. “For over 15 years, we have been the worldwide
reference supplier of radar absorption compounds used in RF absorbers and brackets for blind spot detection and cross traffic alert, for example. Our radar grades are based on many different poly- mers, including PA, PP, PBT and PC. This proven safety experience, together with the trust built over the years with our customers, make development engineers confident of specifying them for autono- mous driving systems up to the highest levels,” Van Bellingen says. Aside from the obvious mechanical, electrical and
fire properties, the move to electric vehicles brings some perhaps less obvious requirements. “EVs make no noise. This means that any squeaking noise inside the car is uncomfortable. For that reason, we have seen an increase in demand for low friction, low wear technical compounds. For instance, our lubricated PA compounds exhibit a stable coefficient of friction over time, which is also independent of temperature and humidity, resulting in constant low wear and low noise. Applications include gears and bearings. PTFE-free solutions are part of our offering,” says Van Bellingen. “There is some hope – although movement is slow so far – that new developments in the battery field will include more speciality plastics solutions to reduce weight and fabrication steps,” she says. “The two major fields that have been overlooked are EMI shielding and thermal conductivity for battery housings and cooling systems. However, technical targets are complex and intelligent mixed materials solutions will certainly have to be consid-
Figure 1: In-plane and through- plane thermal conductivity of a regular Imerys graphite grade compared to Timrex C-Therm high aspect ratio graphite (20wt% loading in PP)
ered.” Van Bellingen says she sees one of Witcom’s key strengths in its ability to formulate compounds with multiple properties, combining EMI shielding, thermal conductivity and flame retardancy, for example.
In an automotive market increasingly influenced by metal replacement and lightweighting to meet environmental requirements, demand for electrically and thermally conductive polymers — mainly engineering plastics and elastomers — is experienc- ing a steady increase, according to Imerys Graphite & Carbon. Miniaturisation of automotive electronics, battery heat management, thermal comfort and passenger well-being are key drivers for increasing demand for electrically and thermally conductive compounds, which it says it can provide with its Ensaco conductive carbon black and speciality high aspect ratio Timrex C-Therm carbon solutions.
Shielding solutions According to the company, one of the fastest growing application areas for electrically conductive compounds is EMI shielding, which is linked mainly to the increased number of sensors and electronic parts on-board EVs. Due to their high conductivity and ease of processing, Ensaco conductive carbon blacks and high aspect ratio Timrex C-Therm are good solutions to providing EMI shielding proper- ties in polymers and in achieving high levels of attenuation in combination with other conductive additives, such as metal fibres. Imerys says Timrex natural graphites and high purity synthetic graphites are well established and bring the highest level of performance to thermally conductive compounds. Its Timrex C-Therm high aspect ratio graphite provides good thermal conductivity at lower additive loading – typically half of the loading needed with standard graphite. This allows greater flexibility to design formulations including ingredients, such as glass fibres or minerals, and to reach optimal mechanical perfor- mance at lower density. Its latest developments in this area include the Timrex C-Therm Max HD and C-Therm Plus HD grades, which are said to offer easier handling and extruder feeding due to improved apparent density.
Ensaco is a conductive carbon black offering high
Source: Imerys Graphite & Carbon
76 COMPOUNDING WORLD | April 2021
purity, high structure and low surface area, together with low moisture pick-up and easy dispersion. This set of properties delivers high levels of conductivity at low loadings, which is a benefit in terms of mechanical and flow properties. The high level of graphitic content of Ensaco also makes it a suitable additive to provide thermal conductivity to poly- mers, especially in applications where high through-
www.compoundingworld.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82
