Overcoming a setback to excel in liquid crystal coating

A decade ago, the first research team Takashi Kuroda joined when he started working at Dai Nippon Printing Co., Ltd. (DNP) in 2002 disbanded after the company experienced a major setback in the marketing of liquid crystal-coated retardation films, a key component for liquid crystal display TVs.

Kuroda, an up-and-coming researcher on a technology called “liquid crystal coating,” had spent five years researching and developing that technology for the component that broadens the LCD viewing angle so viewers can see clear images from various angles. But the emergence of a stretching technology as a cheaper alternative for use in retardation films virtually wiped out liquid crystal-coated films from the market.

“It was so disappointing that our research came to nothing,” Kuroda said. "We felt such a sense of failure, because we had been so determined to make the best films coated with liquid crystals, an organic liquid touted as a superb industrial material that Japan pioneered.”

“We researchers did some soul-searching and talked about what went wrong. We concluded that although we were successful in building the best technologies, we had been too occupied with technological development to seriously give a thought to cost issues.”

After the team was broken up, Kuroda was transferred to DNP's Kuki plant in Saitama Prefecture, where he researched and developed a different type of film also used for LCD TVs. After about five years at this post, top management told Kuroda to return to a research lab at DNP's Kashiwa plant in Chiba Prefecture to develop retardation films again, this time for three-dimensional (3D) TVs. Despite being pleased to return to his original workplace, Kuroda was too busy with the new project to savor the moment.

Liquid crystals align on an alignment film, which directs the crystals to line up in a certain direction by using oscillations from light. This makes it possible to create patterns on a single film—a requirement for 3D TV retardation films, but one that stretched films cannot meet. The original research team knew about this property, but “there was no industrial use for it at the time. We were too ahead of our time,” Kuroda said. “With the arrival of 3D TVs, time finally caught up with us.”

Nonetheless, Kuroda expected technologies that were cutting-edge five years earlier would have already become outdated. This turned out to be an unfounded concern. The new team, comprising old and new members, established technologies for 3D TVs rather quickly, much to their own surprise. “The technologies we developed before were still state-of-the-art, thanks to our efforts to aim for the best, which we had thought was a cause for our failure,” he said. Their endeavors 15 years ago helped DNP become one of the world's leading companies in liquid crystal coating.

Various alignment states of liquid crystal The picture shown is a concept image.

Explaining the state of liquid crystals to people with no background in science often is tricky. Kuroda tries to explain his work by personifying liquid crystals as “pencil-shaped guys.” “We can direct some guys to look right, while instructing others to look left to create a pattern on a film,” he said.

“But some guys standing further from the alignment layer and exposed to the air don't want to follow the instructions,” Kuroda explained. “So we use some additives to fix the problem before solidifying the film.”

But the boom for 3D TVs quickly evaporated, leading major Japanese manufacturers to stop their production by 2017. Fortunately, this setback did not significantly affect the research team, which already had its next project with the arrival of next-generation, organic electroluminescent (EL) displays.

In organic EL displays for smartphones, a component called “the circular polarization plate” is essential to minimize sunlight reflection and ensure images projected on the display are clear by making black blacker in daylight. Retardation films coated with liquid crystals are considered superior to stretched films for this component as smartphone manufacturers strive to make their products thinner and lighter.

“In recent years organic EL displays have been increasingly replacing LCDs as display units, and DNP is one of only a handful of players in the world that offers liquid crystal coating,” Kuroda said. DNP's liquid crystal coating is now used in global brand smartphones and tablets.

Such a development cannot be accomplished by a single researcher. It requires dedicated teamwork. Kuroda, who studied liquid crystals at a Tokyo University of Science graduate school, specializes in optics, an area of study he self-taught after joining DNP. “Our team includes researchers who specialize in liquid crystals, alignment layers and triacetyl cellulose films,” Kuroda said. “If our product is a success, we will all win. We can cherish our victory together.”

Kuroda has known the importance of being a team player since he was a child. He has played soccer since primary school, and his high school team reached the last 16 at a tournament in Shizuoka Prefecture, which was regarded in his teenage days as “a soccer kingdom” of Japan. Kuroda still plays soccer with his high school friends when he goes back to Shizuoka Prefecture for a vacation. “Come to think of it, soccer resembles my work now, because no matter how many goals I score, my team would lose if the other team scores more goals,” he said.

His immediate ambition is to develop liquid crystal-coated retardation films for foldable and rollable organic EL devices. The film must be flexible enough to fold or roll, yet strong enough to withstand the associated pressures. “I think such a gadget will be available by 2020,” Kuroda said. “Everyone involved in this project is working hard to make such a device reality by that time.”

At least until then, the research team's efforts to ensure “pencil-shaped guys” stay well-behaved in pursuit of more advanced technology will continue, as liquid crystal coating remains one pillar of DNP's business strategy.

June 13, 2017 by DNP Features Editorial Department