Precision Coating : Origin and Development

The application of the technology of evenly coating ink leads to the development of functional packaging materials

After Japan’s first supermarket opened in 1953, the demand arose for individual packaging of food products. Having already begun printing on cellophane wrapping paper in 1951, DNP accelerated its efforts in the packaging field, including paper containers and flexible packaging, with the advent of the era of mass production, distribution and marketing. A typical example of flexible packaging then was what in 1958 DNP developed and manufactured for Nissin Chicken Ramen, which is still popular in Japan today.

For this particular product, DNP’s coating technology for thinly and evenly applying ink on the plastic film was an important development. Unlike paper, plastic film does not absorb ink, so a new technique was needed to print on it. Therefore, DNP developed a primer (anchor coating agent) that enabled ink to better adhere to the film. By coating the film with the primer first and then printing ink onto it, DNP was able to print attractive lettering and designs on the film.

The plastic film originally used for the instant noodle product was imported from the United States. Unsuited to Japan’s humid climate, however, the film would wrinkle when it absorbed moisture, which made it impossible to print cleanly and clearly. To solve this problem, DNP independently developed and commercialized a plastic film suited to Japan’s climate. It was necessary to have both an attractive appearance and barrier functions to prevent moisture from entering and the noodle oil from seeping out through the film. These challenges were solved by DNP’s coating and vapor deposition technologies.

Retardation film

A clear view from every angle. This film is key to the evolution of next-generation OLED displays.

The 0.001 mm coating technology that allows OLED displays to express clear color images

OLED (Organic Light-Emitting Diode) displays (OLED*1) are used in televisions and smartphones. They contain a component called a circular polarization plate that prevents the reflection of light from the outside, making the black color stand out more clearly and making the image clearer from every viewing angle. Retardation film is indispensable in this circular polarization plate. The film is given a certain orientation when an photo-alignment film is coated and polarizing ultraviolet light applied, and then liquid crystals are aligned on the film and fixed in position using the power of light. When the film is combined with a polarization plate, the circular polarization plate is ready to use.

One characteristic of OLEDs is their thinness. Therefore, the internal components must be even thinner. To make this possible, capitalizing on advanced precision coating technology, DNP creates both thin and wide film products with a uniform coating thickness.

  • *1: OLED = Organic Light-Emitting Diode

Our technology for transferring only the liquid crystal layer allows us to create even thinner, lighter products

DNP’s retardation film is suitable for OLED smartphones and tablet devices that always need to be thinner and lighter. To make the film thinner, we developed a technology to transfer only the functional layer of liquid crystal to the polarizer. The base film is peeled off and disposed of like the peel-off backing of a sticker after the liquid crystal has been transferred. This brings thickness of the LCD down to 0.001 mm, which is about 1/50th thinner than film products with the same functionality. DNP has been developing and manufacturing display products since the time before OLEDs were available and has been researching and developing products that would make it possible to make retardation films. In other words, the accumulation of DNP’s cutting-edge display product technologies has resulted in the clear and beautiful images produced by OLEDs.

DNP makes further technological contributions to evolving OLEDs!

Left: With circular polarization plate / Right: Without circular polarization plate

In the world of displays, OLEDs are thought to have greater potential than LCDs. Unlike stretched film, retardation film made with coating technology is resistant to bending and stretching. By taking advantage of this characteristic, we may even be able to create a tablet that can be rolled up. In the future, there will be an even greater need for products that are even more beautiful, thinner and lighter. In response to such demand, we will continue to meet and exceed the increasing expectations for our technology.

Battery pouches for lithium-ion batteries

Applying precision coating and post-processing technologies to make rechargeable battery casings lighter, longer lasting and safer.

Lithium-ion batteries required to be lighter and thinner

Used in many kinds of mobile devices, lithium-ion batteries are constantly required to be lighter in weight and thinner, and DNP’s battery pouches help make that possible. While conventional battery casings are made of metal, these pouches are made using a thin, lightweight film. Also, the surfaces of the pouches must be strong and corrosion-resistant to protect the substances inside the battery.

The battery pouches are made of hermetic laminated films with multi-functional coatings so the substances inside will not leak, as a result of the combination of two printing technologies: precision coating and post-processing.

DNP as a pioneer in developing battery pouches

DNP began developing battery pouch technology in the 1990s. At that time, the practical application of lithium-ion batteries was just beginning, but DNP anticipated their rise as next-generation batteries. The Company succeeded in commercializing its pouches for lithium-ion batteries in the latter half of that decade, and since then we have worked to make them multi-functional through coating, and thinner by laminated materials.

DNP’s battery pouches have pristine surface materials. This was not simply for the purpose of making the products attractive in appearance. Rather, it reflects the Company’s priority on safety—the materials encasing the battery’s hazardous substances are carefully inspected for even the slightest flaws. Consequently, the pouches have earned an excellent reputation among customers.

Promoting environmentally friendly electric vehicles to solve social issues

DNP’s battery pouches are also used to encase the lithium-ion batteries installed in electric vehicles. When it first started developing battery pouches, DNP had already envisioned their eventual application in electric vehicles.

DNP is striving to make further advances in this technology to contribute to the goals of decreasing the weight of lithium-ion batteries and increasing their energy density. Attaining those goals would increase the mileage and operating range of electric vehicles, making them even more popular with consumers in the future. In this way, DNP aims to contribute to environmental initiatives that protect the planet.

Printing technology expansion and enhancement