Bayer MaterialScience: New Application for Makrolon®

An interesting new application has emerged for Bayer MaterialScience’s AG Makrolon® polycarbonate. It is being used for the first time in the production of diffuser sheets for large-sized flat LCD screens. ‘Our material has several advantages over polyacrylates such as PMMA, which is the most important competitor material for this innovative application. It has induced screen manufacturers in South Korea and Taiwan, for example, to use polycarbonate for diffuser sheets in the production of large LCD screens,’ says Dr. Claus Rudiger, an LCD expert in the Polycarbonates Business Unit. In view of the growing popularity of home cinema, it is reliably predicted that this kind of flat screen will enjoy considerable market success in the future.
Diffuser sheets are used on the back of the monitor in the backlight unit which illuminates the picture-generating LCD. Their function is to convert the light from special ultra-bright fluorescent tubes into diffuse, uniform, two-dimensional light, and transmitting it to the liquid crystal display without loss. ‘Our tailor-made variant of Makrolon® has better optical properties than PMMA. The diffuser sheets made from it therefore produce a much brighter light, which benefits image quality. They can therefore be made thinner than their PMMA counterparts,’ explains Rudiger. The brightness criterion is very important for picture quality because only around 10 percent of the light produced by the fluorescent tubes actually reaches the eye of the TV viewer. Most of the rest is absorbed by the LCD. ‘The key in developing the new material was to simultaneously optimize what are basically two contrasting material properties, namely light transmission and light scattering,’ notes Rudiger.
The new PC product grade is also superior with respect to its mechanical and thermal properties. It is much more heat-resistant and dimensionally stable than PMMA and also has lower water absorption. This ensures that the diffuser sheets basically do not lose their shape and that the LCD is always illuminated evenly over its entire lifetime. When processing the sheets and assembling the screens, the high impact strength and break resistance of polycarbonate come into their own. Greater safety also results from polycarbonate’s higher fire resistance, because it does not produce flaming droplets.
‘We succeeded in developing the new Makrolon® grades in just 18 months,’ says Fumika Kaneko, Global Key Account Manager with Bayer MaterialScience in Japan. ‘This is down to the close cooperation with the South Korean manufacturer of LCD panels and a large Taiwanese producer of backlights - an excellent demonstration of how we work closely with our customers.’ Bayer MaterialScience will produce the diffuser sheets itself. ‘We are globally positioned in the sheets business as regards production, marketing, technical service and sales. This means we can supply potential customers of diffuser sheets direct in all the key economic regions, and provide our services locally,’ says Kaneko.
With sales of EUR 10.7 billion in 2005, Bayer MaterialScience AG is one of the world’s largest polymer manufacturers. Its main fields of activity are the production of high-tech polymer materials and the development of innovative solutions for products used in many areas of everyday life. The main consumer sectors are the automotive, electrical/electronics, construction, sports and leisure industries. Bayer MaterialScience has production facilities at 40 sites around the world and a workforce of approx. 18,800. Bayer MaterialScience is part of the Bayer Group.

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