Toyobo recently announced the development of a prototype optical film made from 100% plant-derived polylactic acid (PLA) resin, with samples to be available starting in September 2025. Utilizing a unique biaxial stretching technology, the high light transmittance and low refractive index of PLA are maximized. Emphasizing its ability to transmit light across a wide wavelength range, the company aims to promote it as an optical film for use in semiconductor manufacturing processes and display inspection processes, striving for early application.
PLA is a 100% biomass-derived resin made from starch or sugars obtained from plants. Because the CO₂ absorbed by the raw materials during plant growth is offset by the CO₂ produced during waste disposal or decomposition, it is considered a sustainable material that contributes to carbon neutrality. Furthermore, PLA possesses excellent transparency, allowing transmission of light across a wide wavelength range, including ultraviolet, visible, and infrared light, and boasts an optical property second only to fluoropolymers in low refractive index, making it an ideal material for laser manufacturing processes. With these properties, polylactic acid (PLA) holds promise for applications in optical inspection and processing during semiconductor and display manufacturing.
However, to meet the demands of such industrial applications, properties such as heat resistance, mechanical strength, and dimensional stability during processing are also required. Furthermore, to stably exhibit the unique optical properties of PLA that are not found in general-purpose PET films, precise control of crystallization and molecular orientation, which affect transparency and refractive index, is necessary, thus requiring advanced processing techniques. Under conventional processing conditions, the optical properties of PLA are easily damaged, making it difficult to produce films that fully realize their performance.
To address these challenges, Toyobo has developed a new type of PLA film that combines the heat resistance and mechanical strength required for industrial applications with the excellent transparency and low refractive index required for optical applications, utilizing its unique biaxial stretching processing technology accumulated over many years and its particle-free internal structure design technology. Samples are already being provided.
Compared to traditional PLA films, this newly developed film exhibits significantly improved mechanical properties such as tensile strength and dimensional stability. In addition, its unique particle-free structure and surface coating treatment not only endow the film with high light transmittance and low refractive index but also provide excellent surface smoothness and adhesion to other materials.
These properties expand the applicability of this film in laser equipment used in manufacturing processes. For example, when used as a base film in semiconductor manufacturing processes, it is expected to improve the efficiency of processing using short-wavelength, high-energy ultraviolet light and the precision of finished products; when used as a protective film for LCD screens, it is expected to improve the inspection accuracy when using visible light to detect pixel defects. Furthermore, because the refractive index of this film is close to that of glass, which is generally considered to have an extremely low refractive index, it will not affect visual clarity when used in conjunction with glass for shatterproof applications.
Toyobo has already launched several high-market-share industrial film products, including "CosmoShine SRF®" polarizer protective film for LCD panels and "CosmoPeel®" release film for multilayer ceramic capacitor manufacturing processes. Going forward, Toyobo will vigorously promote its newly developed polylactic acid film with excellent optical properties, further expanding its industrial film product lineup to meet the diverse needs of its customers.
