Automotive glazing Glazing at the Motor Show (first part) The first part of this report on the Tokyo Motor Show highlights the technological innovations achieved by Japanese automotive producers regarding environmentally friendly cars. The author then goes on to analyse in detail the glazing trends which emerged at the exhibition. The most evident of these was: the increased use of privacy for rear lateral and backlight windows, reduced UV penetration for solar control, water repellent coating on front lateral windows, and special combiners for HUD on the windscreen.

Giovanni Manfré* MG CONSULT

ntroduction At the Tokyo Motor Show (TMS), Current Japanese vehicle pro- automotive glazing trends were clearly revealed duction shows a decrease in the as strongly connected with the turn cars are domesticI market as opposed to an increase in taking. These trends can be summarized in the the foreign market. has seen the following points for Japanese glassmakers: internationalization and globalization of its ¥ from the solar control point of view, glazing production of car parts, including its is tending more and more towards UV automotive glazing. Some Japanese companies blocking and the use of privacy , are working together with foreign firms: Asahi which have seen a great increase in Glass with Glaverbel, Nippon Sheet Glass with production. In addition, automakers are still LOF, and Central Glass is looking very interested in heat insulation; for partnership to acquire foreign technologies. ¥ water repellent glasses are currently the most Meanwhile, the imported car market in Japan is innovative as far as glazing is concerned, continuing to grow. followed by the solution for the combiner of

145 Glass-Technology International 5/1998 Website: http://www.glassonline.com the HUD with the windscreen to improve the market. At TMS, a great effort was put into information system in front of the driver, on showing that the automotive field is seriously the dashboard and on the windscreen. There and strategically thinking in terms of have also been innovations in screen printing environmentally friendly cars, which means: regarding the edge to edge printed peripheral ¥ technological breakthrough in engines and rim and the five printed antennas on the back transmissions that improve fuel economy; and side windows. ¥ working with users to improve fuel Besides, the colourful dashboards and trims efficiency;

require the aid of anti-reflective internal ¥ discovering new ways to curb CO2 emissions glazing in the front area of the car. The by improving fuel efficiency. increase in display will demand an increase in Special attention was dedicated to deve- the use of thin glasses, as well; loping the electrical and hybrid cars to attempt ¥ “emotional technology,” now called “Kansei to sell them at prices affordable to customers, at engineering”, is being applied by automakers the same or at a cheaper price than conventional and can affect the shape, dimensions, vehicles. peripheral geometry and rake angle of glazing. In fact, emotional technology helps Fuel cell technology designers in structural, chromatic and One of the main forms of alternative energy glazing analysis. The first results seem to be for vehicles presented at TMS was fuel cell the more colourful dashboard and trim with technology, which converts methanol into ergonomic concepts created by the use of hydrogen to produce electrical power for cars. different colours and the less roundish shape In order to reduce current fuel consumption, for of Japanese vehicles. The complex shape of instance, a GDI direct petrol injection is applied glazing will therefore not see great to the front of engines by Mitsubishi. development in Japan anymore, seeing that it Using hydrogen as a fuel, or the concept of has already reached maximum levels of hydrogen storage, is still a dream for innovation; automakers. Another possibility would be that ¥ FCEVs (fuel cell electrical vehicles) will of producing H by catalyst + heat, which influence glazing, to some extent. These cars 2 originates through a chemical reaction of must be designed with suitable weight methanol: CH OH + H O = 3H + CO ; the H reduction, solar control, air conditioning, 3 2 2 2 2 produces energy in combination with oxygen in acoustic and thermal barriers, water repellent the air producing water (H O), which is used and heating glasses, and photovoltaic panels; 2 again in the methanol-water mixed reaction ¥ at the moment, Japanese automotive described above. This is called “fuel cell manufacturers do not seem to be technology”, and the vehicle is the FCEV (fuel concentrating on heatable glasses and cell electrical vehicle), already presented by metallized coatings. They seem content with , and at TMS, and by having reduced the thickness of tempered Mercedes at the Frankfurt Motor Show). This is glasses down to 2.5 mm with new quenching the first time that fuel cell technology has really technologies. received a lot of attention at an international motor show. Principal themes of the show Toyota has developed two kinds of FCEVs, The “leitmotif” of TMS was “One World, both driven by electric motors. Both use fuel One People, One Show”. This can be considered cells to produce electricity, and rely on the dominant theme of the last ten editions, and hydrogen as fuel. Yet, they supply the hydrogen shows that Japanese carmakers are proud of in different ways. One is the metal hydride their international involvement in the world car type, which requires refills of hydrogen gas,

146 Glass-Technology International 5/1998 Website: http://www.glassonline.com 1,600 1,400 Fuel cell technology is thus a new alternative 1,200 to the present petrol engine, even for the United States. Toyota’s technological solution of a 1,000 FCEV power train and similar solutions by 800 Nissan and Mazda as well, can be considered a cc practical step to start off in a serious and 600 strategic way. This can be considered as one of 400 the most important consequences of TMS for the future. 200 However, at TMS, no indication was given 0 as to the glazing for this kind of vehicle, High pressure Liquified Conventional Toyota’s where only transparent plastic was used for hydrogen hydrogen hydrogen hydrogen (200 atmospheres) (-253°C) absorbing alloy absorbing alloy prototypes, with no real strategic orientations (10 atmospheres) (10 atmospheres) or indications.

“Emotional” technology and the other is the methanol type, which runs Fig. 1 Japanese automotive manufacturers are on refills of liquid methanol. Hydrogen currently giving special attention to “emo- The hydrogen-absorbing-alloy-type FCEV storage tional” technology. In this kind of technology, a volume uses a special alloy to store hydrogen on board. structural, chromatic and glazing analysis is per unit There are other methods of hydrogen storage, carried out to translate a customer’s feeling and such as high-pressure and liquified hydrogen image of a product into the design of a car; for tanks (see Figure 1). But the metal hydride instance, the interior colours are designed to be method is by far the safest and most compact, Fig. 2 Colourful ergonomic (see Figure 2) . and unlike other systems, it requires neither cockpit of Structural analysis super-high pressure nor ultra-low temperatures. JWJ The above analysis includes curvature, Mercedes-Benz with Daimler-Benz, too, has SUV corners, integration of projectors, door handles, long been working on the concept of driving cars with fuel cells. Their NECAR, or New Electric Fig. 2 Car, is an electronically powered vehicle which, however, does not obtain its electricity from a battery, but generates it in an on-board power plant made up of fuel cells. The core of the cells consists of a solid electrolyte made of proton- conducting plastic sheeting, which is coated with a platinum catalyst and an electrode made of gas- permeable graphitized paper. Tiny gas channels are milled into bipolar graphite plates on both sides of the catalyst; the channels on one side of the electrolyte carry hydrogen, those on the other side compressed air.

147 Glass-Technology International 5/1998 Website: http://www.glassonline.com Fig. 3 Front view of Ford Taurus, with strong roundish shape

Fig. 4 Rear view of Ford Taurus

Fig. 5 Aristo by Toyota

Fig. 6 Fig. 3 Mazda RX-7 plastic on the side window of the car, polychrome materials with coarse surface and ultra light materials. Chromatic analysis This takes into consideration dashboard, trims, gaskets, polychrome and composite rims, reflections from internal glazing surfaces and dashboard symmetry. Glazing analysis Glazing analysis refers to all-round visibility, solar control coloured, peri- metrically shaped and oval side windows, screen printing and position of sunroof. The author believes that emotional technology is already being used by Fig. 4 Japanese automakers to develop a car

Fig. 5 Fig. 6

148 Glass-Technology International 5/1998 Website: http://www.glassonline.com Fig. 7 Less roundish shape of Mitsubishi’s latest nearly all the innovative vehicles presented for technological car all market segments. The following companies applied privacy glasses: ¥ Toyota in several models, including the Fun Cargo (see Figure 8) and the Grand Cruiser; ¥ Nissan in several models, including the weekend R’nessa; ¥ Honda in many of its vehicles, including the Odissey Prestige and the innovative Accord Wagon (see Figure 9); ¥ Mitsubishi in many vehicles, such as the interior image system which incorporates knowledge of engineering and computer graphics. Fig. 8 - Privacy glasses One immediately recognizable feature in the rear side was, for instance, the front window of the window of Prius by Toyota, which increases the front the Toyota round visiblity. Japanese cars have a less Fun Cargo roundish shape compared to American cars. For example, the Ford Ka and the innovative Ford Taurus (see Figures 3 and 4) are still very roundish, when seen next to Japan’s new Aristo by Toyota (see Figure 5) or the sporty Mazda RX-7 (see Figure 6). The concept car by Mitsubishi, HSR-VI (see Figure 7), the latest advanced technology concept for active safety, has been conceived with a less roundish shape than previous models.

Privacy glasses Apart from already well-known privacy glasses such as GL20 by PPG, Venus by Saint- Gobain, and Galaxsee by Pilkington LOF, Japanese privacy glasses (without going into detail about their state of production in Japan) can be considered the greatest breakthrough of TMS. In fact, just like the explosion of the use of sunroofs at the Frankfurt Motor Show Fig. 9 1997(1),(2), where privacy glasses received a lot The Accord Wagon by Honda, the entire glazing of attention, at TMS privacy glasses were in privacy glass exhibited mainly for the rear windows of

149 Glass-Technology International 5/1998 Website: http://www.glassonline.com RVR-GDI (see Figure 10) and the new Diamante Wagon; ¥ Mazda in vehicles such as the Capella Wagon, but also in small cars like the Melady (see Figure 11), the Bongo Fiendee vehicle and the rear window of the MX-7 sports car; ¥ in many of its cars, including the Class A-level UW-1, the medium-sized Crescent (see Figure 12), the small cars, the Wagon R and the Escudo 4WD vehicle; ¥ Daihatsu, even in the small, compact cars like the Sloper II (see Figure 13); ¥ Subaru in the Forester and the Legacy SUV; ¥ in its SUVs such as the Bighorn XS Plaisir IIC. Fig. 10 It was not possible to discover the real trade

Fig. 10 Privacy glasses in the Mitsubishi RVR-GDI

Fig. 11 The Mazda Melady, example of a small car with privacy glass

Fig. 12 The Suzuki Crescent, example of a middle-sized car with privacy glasses in the corner windows

Fig. 13 The small, compact Sloper II by Daihatsu Fig. 11

Fig. 13

Fig. 12

150 Glass-Technology International 5/1998 Website: http://www.glassonline.com mark of the privacy glasses shown in Tokyo; they bore the names of Japanese glassmakers Asahi Glass, Nippon Sheet Glass and Central Glass, without any mention of the trademark. Consequently, it is the author’s opinion that some of them come from foreign manufacturers such as LOF, PPG or Saint-Gobain. The author’s indication from Japanese car makers is that they appear too dark, especially the GL20 by PPG, as applied to the Chrysler Grand Voyager. The colours used are green or grey, but also brown in many cases. The reason for such an increase in the use of privacy glasses, predicted by the author in Fig. 14 a 1995, could be simply a question of fashion. However, it may also be due to the trend for solar and UV control and the fact that Japanese regulations now allow the use of tinted glasses in the rear windows of all vehicles. In any case, when driving some of the cars (the Honda Accord Wagon, for example), the author had the impression that visibility (mainly the image on the internal mirror) at the rear might create problems, especially in bad weather. This point should be taken into account when adopting dark privacy glasses on the rear window. Japanese glassmakers intend to produce privacy glasses with greater Fig. 14 b transparency from their own batch by the end of 1998 or 1999. The prediction based on current trends is that 50 per cent of vehicles in Fig. 14 UVA (higher ultraviolet light, up to 400 nm, Japan will use privacy glasses. A privacy particularly the range from 350 to 400 nm, glass for the which makes up 54 per cent of the total UV rear window energy of the sun). Thus, if the UV UV and solar control seen from transmission of a glass is given as 10 per cent, outside (a) It has been clear in the last 10 years that, Japanese carmakers want to know the and inside (b) when it comes to solar control, IR absorbing breakdown of UVB transmission (only 4 per and even reflecting glasses, Japanese car- cent in the 200 to 350 nm range, with nearly makers are more concerned about reducing zero transmission in the 300 to 350 range nm) UV, because of its effect on the skin and the and UVA transmission (only 6 per cent in the damage it causes to materials and adhesives 350 to 400 nm range). inside the car. Nippon Sheet Glass For privacy glasses too, Japanese carmakers Nippon Sheet Glass exhibited two types of are very sensitive to UV control, as well as solar control glasses at TMS. The first is an IR solar energy reduction. This trend was also absorbing solar control green batch glass for evident at Tokyo, where a distinction appeared windscreens and front side windows which is between two types of UV reduction: UVB also UV blocking. This has been specially (shorter ultraviolet light, up to 320 nm) and designed for Sedan and Wagon to give brighter

151 Glass-Technology International 5/1998 Website: http://www.glassonline.com control glasses, it presented the integrated IR reflecting glass. Saint-Gobain’s IR absorbing glass is Sekurisol. Both types of glass were presented in Tokyo (see Figure 15), with details of their respective solar control performances, shown in the table below.

TL TE TIR RIR RIE %%%%% Sekurisol 78 49 36 5 6 Integrated IR 77 46 15 60 33 reflecting glass TL = visible light transmission, TE = total solar energy transmission, TIR = IR transmission, RIR = IR reflection, RIE = total energy reflection.

vision from inside the car and at the same time Fig. 15 Asahi Glass privacy from outside. Solar control Asahi Glass presented a lateral window in The second kind of heat and UV control comparison UV cut glass and a 5-layer EC window with privacy glass seems to be a coated glass which between variable transmission levels, which will be acts as a reflecting solar control glass (see Saint- ready for industrial production in sunroofs and Figures 14a and b). It also leaves the area of Gobain’s two side windows by 1999. laminated The UV control window is also fairly IR the brake lights on the rear window fairly glasses transparent and allows the addition of a rear absorbing (up to 1,200 nm) and is applied on screen function through the design of side windows, rear windows and roofs. It seems transparent letters. This multi-functional to be made with a combination of the batch reflective coating for IR reflecting, privacy and technology for green glass and the coating for the design of letters, seems to be a really recent bronze glass. innovation of Nippon Sheet Glass. The EC coloured glass, composed of 5 solid It is very difficult to obtain information layers, has a visible transmission ranging from about it, but it seems to be an organic-metallic 20 to 70 per cent and a total energy transmission coating, applied by a flow or spray process, or from 10 to 50 per cent. alternatively, a special adhesive film. Central Glass Finally, in line with solar control, Nippon Like Asahi Glass, Central Glass treats solar Sheet Glass also exhibited an interesting control, privacy and UV control glass as tempered glass for rear windows with a “shade commodity products already on the market, band”. This acts like a sun visor, reducing heat and therefore not worth presenting in Tokyo as penetration to the rear seat, while also innovative glasses. Its privacy glass is not yet protecting both rear view vision and UV ready for industrial production, but will be by penetration. 1999. At the moment Central Glass buys the Sekurit Saint-Gobain privacy glass from abroad (Venus from Sekurit Saint-Gobain exhibited its already well- Saint-Gobain) and produces some in bronze by known Venus multi-functional glass: privacy, sol-gel coating, already considered too UV control and IR absorbing. Among its solar expensive.

152 Glass-Technology International 5/1998 Website: http://www.glassonline.com The information gained on solar control fluorine on the top surface, seems to have glasses from the Central Glass stand can be started, at least in side windows (including summarized as follows: movable windows). The water contact angle is more than 110°, it has good weather, abrasion Batch glass transmission % and scratch resistance and costs US$ 5-6 per visible solar energy UV piece. solar green 74 47 15 At TMS this solution was represented by: ¥ Nippon Sheet Glass’ Repelite, already quite high UV shield 74 47 8 well-known in the USA. It seems to be in use coated glass 74 67* for windows which undergo wiping, such as (pale bronze) the windscreen. However, experiments have by sputtering shown that while Repelite can resist abrasion for tempering on the movable side window for more than * total energy reflection outside the car is 9% three years, it can only resist the action of wipers for months; Conclusion ¥ Asahi Glass’ water repellent glass, which has The main concern of Japanese glassmakers is quite good characteristics for improving to obtain a multi-functional solar glass which Fig. 16 visibility, mainly in heavy rain and snow; Comparison cuts UV transmission and reduces heat in the ¥ Central Glass’ SiO2 + TiO2 + fluorine coating, front area, and both reduces UV and provides between adopted in preference to its sol-gel, water privacy in the tempered side and rear windows. Central repellent coating presented at Tokyo ’95 and Glass’ water Batch glasses seem the most common multi- considered too expensive. In the author’s repellent functional glasses, although it is not clear how glass and opinion, this seems to be the most advanced and where Japanese solar control and privacy other glass solution. The process seems to start with a glasses are produced. There is certainly an when TiO2 and SiO2 in a solution with an organic increased interest in privacy glasses among all sprayed with solvent. At a high temperature, about 350°C, the nine carmakers, as this report has tried to water the solvent evaporates and fluorine from show. The feeling is that over 60 per cent of cars will adopt UV control privacy glasses in the Japanese market.

Water repellent glasses Together with multi-functional solar control glasses and the combination of HUD on the laminated windscreen, water repellent glasses are the most innovative results achieved on an industrial scale by the three main Japanese glassmakers. They are in line with the carmakers’ need to solve the safety problem of visibility at least in heavy rain or snow. Industrial-level production of the inorganic coating SiO2 +

TiO2, with weather-resistant

153 Glass-Technology International 5/1998 Website: http://www.glassonline.com process through increasing the num- ber of air nozzles (uniformity), making the shape of the whole nozzle quenching area as similar as possible and parallel to the forming glass, and creating a suitable distance between the two. The breakage pattern shown by Central Glass was almost the same as that of a normal tempered glass of 3 mm thickness. This is certainly due to a fairly controlled ratio between the compression and tension distribution through the thickness of the glass, which depends to a great extent on the heat transfer coefficient in the quenching phase. From the infor- mation gathered personally by the fluorite vapour is deposited on the composite Fig. 17 author, it seems that the increase of heat solid layers of T O + S O . Central Glass’ transfer coefficient has been achieved by i 2 i 2 water The coating is only produced at industrial mixing special solid particles with the level for side windows, as its resistance to repellent quenching air. glass, showing the abrasive action of windscreen wipers is Sekurit Saint-Gobain showed two kinds of spherical not yet considered satisfactory. shape of weight reduction at its stand: Figure 16 shows a comparison of two types water droplets ¥ reducing the thickness of tempered glass to of glass sprayed with water, to illustrate the 2.8 mm; difference in transparency between the Fig. 18 ¥ a laminated glass composed of two 1 mm- uncoated and the coated glass. Figure 17 High reflection thick external glasses sandwiching a 0.76 shows a more simple experiment where the on the mm PVB adhesive layer. droplets of water from a tap are almost windscreen Asahi Glass also shows the possibility of spherical and move rapidly down the glass by force of gravity, even though the surface of the glass is only slightly sloped. For a better solution to the problems of cleaning and of water repellent per- formances on glasses which undergo wiping, glassmakers should collaborate more with wiper manufacturers.

Weight reduction Japanese glassmakers are concen- trating their efforts on reducing the thickness of tempered glass to 2.5 mm for side and rear windows. Nippon Sheet Glass, Asahi Glass and Central Glass have obtained the required result by a rationalization of the quenching

Fig. 18 154 Glass-Technology International 5/1998 Website: http://www.glassonline.com reducing weight by using plastics for monolithic glasses and laminated five-layer glass. The latter type of glass not only achieves 30 per cent weight reduction, but also, as a multi-functional glass, solves the problems of acoustic and thermal insulation which remain unresolved in reduced-thickness tempered glass.

Anti-reflecting glasses Current glazing trends have produced a greater need for anti-reflecting glasses, mainly Fig. 19 - Difference between in the front area, partly due to the increased Asahi’s anti-reflecting use of colour, including ergonomic, on the coated and uncoated glass dashboard and trim. Figure 18 shows the high level of reflection from the internal surface of a windscreen in a vehicle with a particularly colourful dashboard: visibility through the glass can be quite unsafe. Figure 19 also clearly shows the difference in visibility between glass with an anti-reflective coating and without. The solution proposed by Asahi Glass and Central Glass is based on two coatings, as seen in Figure 19 by Asahi Glass and in Figure 20 by Central Glass. Asahi Glass seems to have reduced reflection from 8 to 2 per cent and from 15 to 6 per cent on the windscreen, with a strong rake angle. Neither Asahi Glass nor Central Glass gave information about the kind of coating used. However, Asahi Glass mentions an inorganic coating similar to the water repellent coating (possibly SiO2 + fluorine) and Central Glass mentions a particular sol-gel Fig. 20 In the second part of this report, the author Anti- technology and, more recently, a TiO2 coating looks at innovations in the application of HUD as well. This information needs to be reflecting on the windsceen and in mirror technology on thoroughly verified. glass by display in Tokyo. Also discussed is the co- Central Glass design between carmakers and glass companies References: in the production of modular doors, which emerged at the show. 1. G. Manfré “Glazing perspectives at the Frankfurt Motor Show ’97” (first part), Glass Technology International, IX, 1, January/February 1998, p. * Consultant 132-139. MG Consult - Italy 2. G. Manfré “Glazing perspectives at the Frankfurt Motor Show ’97” (second part), Glass Technology International, IX, 2, March/April Entire content © 1998 by Artech Publishing S.r.l. 1998, p. 103-116.

155 Glass-Technology International 5/1998 Website: http://www.glassonline.com