Prise winners list

Development of nanofiber nonwoven fabrics in new electro spinning method

Tosa-City, Kochi Prefecture
Hirose Paper Mfg Co., Ltd.
Other award winners
Koji Ichihara, Shoji Okada, Takuya Kadota, Tomoei Komatsu
Recommended by
Hirose Paper Mfg Co., Ltd.

Kishimoto, Yoshinori  (49)
New Functional Material Dept., Director

If another company can do it, I can also do it! I was quite at a loss and frustrated but finally fund a new idea that defied the common wisdom.

The electro spinning method is a technology that produces nanofibers, the hole diameter of which is several nm (nano meter), by applying high voltage to polymer solution within the fiber spinning nozzles. This technology was established in the 1930s, but it was necessary to install hundreds of thousands of spinning nozzles to mass-produce nanofibers. That technology could not be used for business in Japan because costly equipment investment and complicated maintenance were required. In the new nozzle-free electro spinning method developed by this company, fibers can be taken directly from the entire surface of high molecular polymer solution and nanofiber nonwoven fabrics can be mass produced at low cost. At the same time, the company developed a manufacturing device that has drastically reduced maintenance work.


We attempted mass-production of nanofiber nonwoven fabrics at low cost, which was said to be impossible

"I worked for research and development of polymers at another company and joined Hirose Paper Mfg Co., Ltd. in September 2004. Hirose Paper was a top-class manufacturer of wet-laid nonwoven fabrics but had no new product at that time, with which the company could develop. Therefore, promptly after joining the company, I often visited the library of Kochi University, read many related literatures and found that the nanofibers had great potential."
It is now studied to use nanofiber nonwoven fabrics for sophisticated filters and secondary battery separators for hybrid and electric cars. However, in the conventional nanofiber manufacturing technology "electro spinning method", the hourly production quantity was too small, numerous spinning nozzles had to be installed and so people thought that it was impossible to perform mass-production at low cost.
"I focused on the electro spinning method and started my research to improve it. I visited an international exhibition/technical seminar for nanotechnology in spring 2005. A company exhibited a nozzle-free manufacturing device, in which voltage was applied to a polymer solution and nanofibers were produced from the rotating cylinder surface. I thought, 'Someone defeated me!' and felt very depressed. However, I thought that if another company could do it, I also could do it. I told to myself that I should think positively."
He continuously thought about a new electro spinning method, which did not need nozzles and rotating cylinder, at his company and home, even in his dream, for 24 hours a day. He tried every new idea but only failed. In summer 2005 when he began to feel impatient, a new idea came to his mind like a sign from God. He thought that nanofibers should be discharged from the entire surface of polymer solution and nanofiber fabrics, which were blown to an unwoven base fabric, should be separated from it to make a product. Mr. Kishimoto started his experiment immediately. 
"Its results were far more than what I had expected. The thickness of a produced fabric was about 200nm (nano meter), 1/10 that of a conventional fabric.

A new technology, which demolished the conventional theory, widened the potential of unwoven fabrics

The new nozzle-free electro spinning method developed by Mr. Kishimoto effectively enabled mass production of nanofibers at low cost. In addition, by combining equipment and parts that any unwoven fabric manufacturer has, a manufacturing device can be produced relatively easily. Moreover, this device can increase the fiber spinning quantity easily and can prevent unevenness in basis weight by having multiple units of fiber spinning units. 
"In fact, we succeeded in another experiment to produce nanofibers themselves. However, a maker must manufacture products and sell them. Even a wonderful invention cannot be used for a business if it is too costly. Therefore, we thought that the new electro spinning method was the best and obtained a patent for it. Subsequently, we overcame many difficulties in the process from successful research to manufacturing and are struggling to survive as Darwin's theory suggests. 
The company completed a manufacturing device for mass production in August 2008 and exhibited its devices in domestic and overseas exhibitions for nanotechnology. During its marketing activity, many companies purchased the samples of separators and filters made of its nanofibers and showed their deep interest. 
"Microporous membranes made of olefin, the hole diameter of which is 1000nm or less, are used for a large lithium battery mounted on electric cars. The conventional unwoven fabrics could not have such a small diameter. However, our nanofiber unwoven fabrics consist of fibers, the hole diameter of which is about 200nm and so could enter the market for the microporous membranes. 
When New Functional Material Dept. was started, Mr. Kishimoto was only one member, but it now has twelve members including those of Project Team. Hirose nanofiber nonwoven fabrics that are mainly used for separators will be used widely for highly value-added products such as various filters and medical goods.

Hirose Paper Mfg Co., Ltd.

Mar. 1958
20 million yen
32 (as of Dec. 2009)
Brief information:
Pioneer company of wet-laid nonwoven fabrics. The company manufactures primary battery separators (insulating paper), filter base materials and packing materials for foods and hygiene products.

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The company's original device that manufactures nanofiber nonwoven fabrics. Nanofibers can be combined with the conventional fabrics, or only nanofiber nonwoven fabrics can be taken as needed.


"Hirose" new electro spinning device is installed behind the stainless steel board.


Nanofibers combined with an olefin sheet (thick fibers) mainly made of synthetic resins such as polyethylene and polypropylene. The magnified photo clearly shows how thin a nanofiber is.


Space where a large test machine is to be installed. The machine will manufacture nanofiber nonwoven fabrics of further stable quality at the speed three times as fast as the present model.