Volume 23, Number 1
1999

Gas-Phase Deacidification in Japan

Toru Kibe forwarded to the newsletter office the following news story from Japan in February 1999.

A gas-phase mass deacidification process is now in commercial operation in Japan, under Nippon Filing Co., Ltd.

The problem of acidic papers is also serious in Japan. Japan is now one of the advanced countries using acid-free paper for books, but most library collections, totaling more than 400 million volumes, are still acidic and are deteriorating accordingly.

Several mass deacidification processes are now in operation or under development in Europe and North America, but all of them are liquid phase processes and most of them are for the libraries' own use and not commercially available, because of technical problems and cost.

This new Japanese one, called the DAE process, is a gas-phase process, using dry ammonia and pure ethylene oxide introduced into a vacuum chamber containing books. One batch takes 48 hours. This might seem reminiscent of the former BPA process because of these chemicals, but the ethanolamines formed in books processed by DAE are much more stable than those processed by BPA.

The announced evaluation data are excellent. The rate of decline in the strength of treated acidic paper through accelerated aging can be reduced to one third, or further. Uniformity of reaction is also complete. Control of insects, insect eggs and fungi has been certified as 100% effective. One of the major merits is excellent practicality. They also say the process is simple and little pre-selection of books is necessary, and because the gases have strong permeability, books can be put without any special care in containers that are transportable by common carrier. This process is also effective for old paper as well as new paper. This advantage is important because from now on most books that will be processed will be old ones.

Many studies on the safety and hazard of processed books have also been conducted producing a great deal of data, because they contain amine, though ethanolamines are allowed to be used as a material in cosmetics in Japan and the U.S. One of the few disadvantages is a decrease in brightness. It is only noticeable when the treated and untreated papers are compared, and the difference starts to disappear and even to reverse after the accelerated aging.

Another problem is an increase in the thickness of processed books by around 2%, which is inevitable, supposedly because of physical effects of the process.

Joint development of the DAE process was begun in 1992 by a group of paper scientists at Tokyo University of Agriculture and Technology and a private company, Nippon Filing, Tokyo. The university group had studied the fundamental process of acidic deterioration and its control, and also studied many existing mass deacidification processes, including WeiT'o and DEZ, even operating their own experimental plants for some years before developing DAE.

Commercial operation began in December 1998, and their capacity as of February, two months later, is 2,500 volumes (= 2,000 kg) per batch. That amounts to about 400,000 volumes per year, but the capacity can be easily expanded to 1,200,000 volumes.

For information about industrial/commercial aspects, contact:

Empei Tajima, Chairman, Nippon Filing Co., Ltd.
1-6, Kanda Surugadai, Chiyoda-ku
Tokyo, 101-0062, Japan.

For scientific information, contact:

Takayuki Okayama, Assoc. Prof.
Laboratory of Recycled Resources Science
Dept. of Environmental & Natural Resources Science
Tokyo University of Agriculture and Technology
3-5-8, Saiwai-cho, Fuchu
Tokyo, 183-8509, Japan.

An English-language publication is available from Nippon Filing Co., Ltd.: "Dry ammonia-ethylene oxide process for mass deacidification," by Dr. Reizaburo Oe, Dec. 1994. The author is Prof. Emeritus, Tokyo University of Agriculture and Technology.