Prise winners list

Development of innovative coating process that reduces use of harmful chemicals

Kami-town, Miyagi Prefecture
Kami Electronic Industry Co., Ltd.
Other award winners
Kami Electronic Industry Co., Ltd., / Noriaki Hayasaka, Katsuzo Yokishita
The National Institute of Advanced Industrial Science and Technology, / Takashi Aizawa, Sanenobu Ono, Shinichiro Kawasaki, Akira Suzuki
The Industrial Technology Institute, Miyagi Prefectural Government, / Ikumasa Sato, Tsuyoshi Chiyokubo, Tomoo Nakatsuk
Recommended by
The Industrial Technology Institute, Research Center for Compact Chemical Process

Hayasaka, Yutaka  (60)

Located just in a rice-producing area in Miyagi, we wish to promote our coating technology, which reduces the environmental burden, in the world market

This company performs coating, surface treatment and machining for the housing of cameras and mobile phones, resin parts of automobile instrument panels, etc. The company started basic research to replace the volatile organic compound (VOC), which was diluting solvent for coating, with supercritical CO2 in cooperation with the government in 2005. It conducted research and development of this new technology under the basic technology development program by the New Energy and Industrial Technology Development Organization (NEDO) for two years in 2007 and 2008. Currently a practical machine is operated in test and paint dedicated for CO2 is being developed. This new coating process reduces the usage of VOC to 1/3 the conventional one. It also reduces the CO2 emission by streamlining the entire coating process. The practical use of this technology will be started within this year. And people in the automobile, home electrical appliance and household furniture industries are greatly interested in it and looking forward to it.


Total elimination of organic diluting solvent, an essential item for spray coating, by use of super-critical CO2

The emission control of volatile organic compound (VOC) based on the Air Pollution Control Act was enacted in 2006. The relevant companies should reduce their VOC usage by 30% compared with 2000. 
"Coating companies like us wished to reduce their usage of VOC, but could not find a substitute for organic solvent such as toluene and xylene that were used to dilute paint. However, we found by chance that carbon dioxide (CO2) could be used as a substitute."
We participated in the "Supercritical Fluid Incubation Consortium" organized by the Research Center for Supercritical Fluid Technology in 2003. The supercritical fluid means the special state of a material at a certain pressure and temperature, in which the material has both properties of gas and liquid. CO2 becomes supercritical fluid, which has special properties that it does have not when it is a gas or a liquid, at 7.38MPa and 31.1C.
"We thought at first that we could use the high dissolving power of supercritical CO2 to clean parts before coating them. However, it was not good enough practically. Then we thought that we could use supercritical CO2 to dilute paint as a substitute of thinner. 
In spray coating, paint must be diluted with organic solvent to decrease its viscosity. The amount of solvent used is the same as that of paint in weight. If the thinner can be completely replaced with CO2, the amount of VOC used can be reduced to 1/3. Only the VOC that is contained in the original coating material remains. The company started research jointly with the AIST Tohoku and The Industrial Technology Institute, Miyagi Prefectural Government, in 2005. At first, however, when he saw the test samples of coated product, he was doubtful of the research. 
"The coated surface was irregular like a frosted glass and I became doubtful. However, I was interested in the supercritical CO2 because it was harmless and could be used for flammable paint at normal temperature."

By using CO2, total emission of it in the entire coating process is reduced

At the first stage of their development, they chose clear paint, which contained no pigment polymer, from the existing paints and checked the compatibility between it and CO2. When CO2 was mixed with the clear paint, the strong melting power and high pressure of CO2 reduced the viscosity of paint. In addition, the usage amount of it was only 1/3 that of the paint. However, we had many problems for a coating device. We had to find proper timing for mixing of paint and CO2.
"Supercritical CO2 and paint had to be mixed in a mixer 'quickly at a time'. While mixing them, we had to send them to a spray gun to spray them. We had to perform this process continuously without decreasing the pressure within the mixer."
By using a micro-mixer, they mixed the paint and CO2 instantaneously and installed a pressure-resistant glass window so that they could see the interior of mixer. When the clear paint and CO2 were mixed successfully, the interior looked transparent. When they were not mixed successfully, the clear paint was separated and the interior became obscure. Since the supercritical conditions were made visible, their experiment progressed smoothly. 
"The nozzle diameter of conventional spray gun was too big and so too much paint was sprayed at a time. By developing a high-pressure spray nozzle and improving the operating conditions, finally we could perform coating stably in fine particles without adding diluting solvent. There was no paint dripping. We forgot all the concerns we had at the early stage and thought that our new technology could be used successfully."
These experiments bore fruit at last, and the finished coating film was thinner, stronger and more beautiful than the conventional one. Development of dedicated paint for CO2 is progressing and a new practical device will be put on the market this year. However, only one concern is that the amount of CO2, a greenhouse gas, is increased while that of VOC is decreased. 
"People often say so. But we use CO2 that was exhausted by factories and collected by us. In addition, when we consider the entire process from manufacturing of paint to coating and drying, the total amount of CO2 emission is decreased compared with the conventional coating."
Then let us compare this new coating with the water-based paint, which many carmakers are using in order not to use VOC. For use of the water-based paint, the washing process before coating is time-consuming more than the same for organic solvent and strict control of temperature and humidity is required for coating and drying processes. When we consider the total amount of consumed energy, the total amount of CO2 emission is smaller in our new system. 
"Even if the new system is introduced, the existing production line for organic solvent paint can be used almost without any modification. In addition, any extra paint diluted with thinner had to be disposed of. In the new system, however, such a waste can be eliminated and the total running cost can be reduced."
In a presentation organized by the Miyagi government to invite the automobile industry, this coating system attracted great interest of visitors. If an advanced technology in a local city is more useful to attract companies to that region than "preferential treatment" by a local government, what an interesting topic it is.

Kami Electronic Industry Co., Ltd.

Jun. 1970
48 million yen
126 (as of Dec. 2009)
Brief information:
The company performs surface treatment and machining of electronic, mechanical and optical components (coating, screen printing, sheet printing, hot stamp, press work and laser work) in one integrated production.

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Test device for supercritical CO2 coating


They can see the supercritical conditions within the mixer through this window.


They introduced a quantitative assessment method of coating film quality.