Toray Industries Inc developed a film to which grease such as fingerprint is hardly attached. And even when it is attached to the film, it can hardly be seen, the company said.
The film is targeted at smartphones, tablet computers and other devices equipped with a touch-sensitive display.
"We will see how users will respond to it," said Tetsuya Tsunekawa, general manager, Films and Films Products Research Laboratories of Toray. "But we want to start volume production in fiscal 2012 at the earliest."
Currently, there are two types of fingerprint-resistant film products. One is a lipophilic film, which spreads grease so that it can hardly be seen. The other is an oil-shedding film. According to Toray, a lipophilic film loses its effects when it is touched by a finger with much grease, etc. And fingerprints on an oil-shedding film tend to be highly visible, it said.
Toray claims that the new film does not have those problems. When the company evaluated the film by using its original index called "fingerprint resistance," its resistance turned out to be "Class-2," which is superior to the resistances of competing products ("Class-4" of a lipophilic film and "Class-3" of an oil-shedding film). The fingerprint resistance is quantified based on the variation in the color and luster of the light reflected on the surface of a film. The lower its value, the higher the properties.
The total light transmittance, haze and gloss level of the new film are 91%, 0.6% and 155%, respectively, which are equivalent to those of competing products. The production cost of the film is low because it is made by coating a PET (polyethylene terephthalate) film with a solution, Toray said. It is also possible to make the film by coating other resin films or glass.
To realize those properties, Toray employed two techniques. First, the company improved oil-shedding property to prevent the film from being stained. It used a new add-in material so that an oil-shedding material can be easily dissolved in the base material and a film can be uniformly formed. As a result, the amount of dirt attached to the film is about one-third that of an existing oil-shedding film. The company did not disclose the names of the materials used for the film.
Second, nanometer-size concave and convex structures were randomly formed on the surface of the film so that dirt does not concentrate and become visible.
"By optimizing the composition ratio of the base material, oil-shedding material and add-in material as well as the coating and drying processes, it became possible to add a self-organizing function and form minute concave and convex structures," Toray said.
The company will exhibit the new film at the 11th International Nanotechnology Exhibition & Conference (nano tech 2012), which runs from Feb 15 to 17, 2012, in Tokyo.