AUTOMOTIVE | SURFACES
Right: BASF’s Deep Gloss demonstrators
in black, but BASF said it is open to discussions on colours. Evonik, too, sees a growing need for
PA-based materials for high-gloss automobile interior parts. One example shown at Fakuma, a test part in a project it is currently involved in, is made in a grade of Trogamid CX, which is a PA PACM 12 (cycloaliphatic diamine dodecanedio- ic acid). Evonik said this has higher chemical resistance, thanks to its semicrystalline nature. Trogamid CX compounds also have a high level
of UV resistance, low water absorption, high dimensional stability, high impact resistance, even at low temperatures, and abrasion and scratch resistance. These materials have been on the market for some time, but mostly for technical parts and often for over-moulding; now it is also being used in mono-material automotive parts as well. Evonik is also a leading producer of PMMA,
Below: Evonik’s new Plexiglas grades provide diffusion in coloured as well as uncoloured parts
which, as already noted, has long been used for exterior pillar covers because of its high gloss and very good weather resistance. Now, say company executives, more high gloss trim is appearing on the inside; but while exteriors require more scratch resistance, having to pass car wash tests for example, chemical resistance takes on more importance for interior trim, so they can resist products such as sun and hand creams for exam- ple. For such applications, Evonik offers Plexiglas FT15, which has particularly good flow, very good scratch resistance and improved chemical resist- ance. Its very high purity allows production of parts in any colour, including intense blacks. Plexiglas NTX 15 is also said to have very good
resistance to micro-scratching caused by wiping with dry textiles. This product is modified with an additive that improves its surface properties without affecting opticals. In exteriors, PMMA is known as a rather brittle material, but now Evonik offers Plexiglas NTA5, an
impact modified high gloss type for unpainted products such as front grilles and panels on the lower body. Sven Schroebel, Head of Product Management Automotive, Methacrylates - Moulding Compounds, said it has the advantage of being transparent to radar, while the paint on PC or ABS causes transmission losses. He also pointed out that while impact modifiers normally make PMMA go slightly milky, it is still possible to obtain high gloss blacks with NTA5. Turning to the rear of the vehicle, Schmitz pointed to the trend to light diffusion systems for LEDs, so that individual LEDs are no longer discern- ible. Evonik offers materials that enable diffusion, not only with white parts but also with colour. Plexiglas 8NDF23 Red is one example, already used on some Opel models. “You get an OLED effect without the expense of the OLED,” says Sven Schroebel, Head of Product Management Automo- tive, Methacrylates - Moulding Compounds. Back to the front, but this time to lighting, Evonik notes that materials used as optical elements in car headlamps must satisfy stringent requirements on light transmittance, temperature resistance, and UV resistance—as in the case of the three Plexiglas and Pleximid moulding compounds in the LED Intel- ligent Light System from Automotive Lighting, which Mercedes-Benz is installing in its C-Class. For all their advantages when used in head-
lamps, LEDs also put the material used in them to a hard test, Evonik executives say: depending on the type and design of the optics, temperatures of well over 100°C can arise, and over long periods of operation. But light covers, lenses, and lightguides must not deform, discolour, or become opaque. “That really can’t be taken for granted in transpar- ent plastics,” says Martin Mohrmann, senior technical marketing manager Automotive at Evonik. “Materials like polycarbonate and even its temperature-resistant variants can yellow over time.” (It should be pointed out that PC majors like Covestro and Sabic are getting on top of this
48 INJECTION WORLD | November/December 2017
www.injectionworld.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