Above: Evonik’s Plexiglas range of neutral grey colour grades

describes developments for what he calls dual designs in FIM. Previously, he says, the technology involved screen printing on the second surface, followed by forming, trimming and back moulding of decorated standard or hard coated PC films. “Nowadays, due to the development of chemi- cally and abrasion resistant dual-cure screen printing lacquers, the films can be decorated from both sides, for example for creating matt/gloss or 3D effects or special dual designs,” he says. Dual design means that a transparent PC film is first surface decorated, for example with a haptic aluminium brush effect. Here, a semi-transparent silver layer is put on first, and then overprinted with a thick line structure of a the highly resistant Norilux DC (dual-cure) lacquer. The second surface of the film can be decorated

with, say, a photo-realistic wood or stone image, us- ing four-colour screen printing with Pröll’s new NoriCure IMS UV-curing inks. “The first ink layer on the second surface is a

semi-transparent black, to prevent a shine-through of the image,” Zäh explains. “The wood image is then back printed with a white tinted adhesion promoter.” The decorated PC film can then be thermofor-

Below: EVs will have new front and rear end lighting concepts. Pics: Evonik

med, UV-cured and back moulded, to create a part such as an HVAC front panel. When panel is unlit, the brushed metal effect shows up. When it is lit from behind, the wood image is visible. Evonik Performance Materials discussed its own developments in what it calls “secret until lit”

displays at the show, based on its Plexiglas polym- ethylmethacrylate (PMMA, or acrylic). In this case they have a high gloss uniformly black or grey appearance until LEDs behind them are switched on to reveal information. Sven Schröbel, Head of Product Management, Automotive, Methacrylates, showed a new kit that the company has developed to help designers choose the correct material for their application. One new grade of acrylic is 7V376. This diffuses the light from the LED more than other grades intended for displays, but unlike those grades, the original colour of the LED still shines through. Other new developments in Plexiglas include

AG100, which has improved resistance to impact and to heat, which is currently being trialled at customers for possible use in electric vehicle fronts incorporating light guides. Schröbel points out that this Plexiglas does not need a protective coating for use in such applications. As an indication of the very good aesthetic

properties of PMMA, and their high UV resistance, Schröbel points to its growing use, uncoated, in car badges, where previously decorative film technolo- gies might have been used. He says colour reten- tion over time in Plexiglas badges is much better than in badges with film decoration. Problems with brittleness in PMMA have been addressed, he says. Schröbel also points to the superior heat ageing

properties of PMMA compared with polycarbonate. He says that even in applications where high-power LEDs are positioned close behind the part, there is no yellowing over time. In fact, he says, yellowness actually falls. Furthermore, PMMA has much better light transmission than PC, which he demonstrates with the aid of two rods 1 m long, one in each material. If a torch is shone onto the end of the polycarbonate rod, virtually no light emerges at the other end. With the acrylic rod on the other hand, a strong beam emerges. PMMA has a light transmis- sion of 92%, compared to 89% for PC; the differ-


INJECTION WORLD | November/December 2018

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