As an alternative to glass, "transparent polyimide" has attracted much attention
Polyimide is a plastic material suitable for films, coating agents, photosensitive resins, and electrical insulating materials. It is widely used in various fields from electronic parts, automobile parts to artificial satellites and space probes. Polyimide has a higher thermal decomposition temperature (500°C or higher) than other plastic materials. It is not only heat-resistant, but also an excellent material in terms of mechanical and scientific properties. Recently, with the development of under-panel camera and foldable smartphones, the potential as a display material is also increasing.
One of the characteristics of ordinary polyimide is that it has a yellowish-brown color due to its chemical structure, and cannot be used in applications requiring colorless and transparency. The coloring is because the conventional polyimide raw material has an aromatic skeleton (benzene ring skeleton). To make it colorless and transparent, the polyimide raw material (acid dianhydride) can be changed from traditional aromatic monomer to alicyclic monomer. However, such a method cannot maintain sufficient heat resistance and dimensional stability, and therefore it is difficult to use it in the same applications as colored polyimides.
However, in recent years, transparent polyimide has attracted attention as a glass substitute material in liquid crystal displays and organic EL displays.
The industry has also predicted that there will be a transparent polyimide market in the near future since more than 10 years ago.