JAPAN TAPPI JOURNALVol. 56, No. 7

July 2002 Abstracts


Outline of pulp manufacturing technology
Makoto Iwasaki
Oji Paper Co., Ltd，Pulp & Paper Research Laboratory

　This paper is consisted by four parts. In the first part, outline of the change in raw material used for paper in Japan was described. In the second part, pulp manufacturing processes such as kraft pulp(KP), mechanical pulp(MP) and deinked pulp(DIP) were briefly introduced in terms of their histories, pulp qualities, flow-sheets and changes of annual production rate. In the third part, the four recent topics of pulp manufacturing technology in Japan were introduced. Such topics were included with AQ added KP cooking, two stages O2 bleaching of KP, deinking process change corresponded to newspaper printing system change from letter-press to off-set, and improvement of DIP brightness from about 50% to 70%+ were introduced. In the final part, the recycling technologies in pulp manufacture both for KP and DIP would be believed more important in the future more than past.


The General Technology for Recycled Pulp
Yoichiro Isono
Daishowa Paper Mfg. Co., Ltd.，Senior Manager / Production Management Dept.

　In order to protect global environment , save natural resources , recycled pulp has been expanded rapidly in recent years.
　The recovered paper utilization rate 56% target in fiscal year 2000 was achieved the two years ago. It is expected to be decided that a new utilization rate target was set up to be 60% in fiscal year 2005 by the Japan Paper Association.
　Recently some new technologies for deinked pulp have developed in some fields. These new technologies will be able to achieve the new target.


Waste paper recycling
Yuichi Irinatsu
Kao Corporation，Performance Chemicals Research Laboratories

　Pulp and paper industry is aiming to raise the percentage of waste paper recycling to 60% by 2005 and makes efforts to reach this target. Under these circumstances, developed deinking technology is severely required. The deinking is indeed one of the process industries and is mainly consisted of ink releasing and ink rejecting. To control the ink particle size in each process is very important in order to obtain the good deinked pulp. For example, in the ink rejecting process, more than 95% of larger ink particles than 4 um is easily rejected by the flotation cells. This means smaller ink particles than 4 um are hardly rejected. Residual small inks make the deinked pulp grayer and result in poor printability. Coagulation of the small ink particles decides the deinkability in flotation. On the other hand, ink releasing relates to the penetration of the chemistry into the waste papers. Therefore, the phenomena in each deinking process can be understood by surface science and the deinking agent controls these phenomena.
　To achieve the above-mentioned target, lower grade waste papers, such as old magazines, which have not been used as a furnish will be deinked and for these waste paper deinking, developed deinking agents which have better ink releasing and sticky removing abilities will be needed. Based on surface science, we have developed the new deinking agent whose ink releasing ability is improved 20%. The special surfactant has been also developed to reduce the sticky. By using this surfactant, the sticky is removed 1.2 times as much as the conventional deinking agent.
　A deinking agent has been thought as a ink removing agent. From now on, concerning the pulp quality as a furnish, we are going to continue to develop the deinking agent as a pulp recycling agent to produce the better deinked pulp.


Foundation of Recycled Pulp Bleaching Technology
Tetsuo Koshitsuka
Mitsubishi Gas Chemical Company Inc., Tokyo Research Laboratory

　The amount of production of the hydrogen peroxide in the year 2000 was 145,744t. The demand for pulp is 71,237t and the ratio has reached 48.9%. Also, about 60% of the demand for this pulp has been estimated as demand for recycled pulp. Therefore, recycled pulp is an important field of the hydrogen peroxide market.
　Seven kinds of oxidizing agent (chlorine, hypochlorite, chlorine dioxide, hydrogen peroxide, oxygen, ozone, peracetic acid), three kinds of reducing agent (sodium hydrosulfite, sodium borohydride, formamidine sulfinic acid) were described and especially hydrogen peroxide, sodium hydrosulfite, and formamidine sulfinic acid were described in detail as important bleaching agent.
　 Concerning hydrogen peroxide, the influence of metals, the heat of kneader and catalase were described. The preventative measures were also described.
　Concerning sodium hydrosulfite, the decomposition by air, water and combustion by water were described. As a measure, "HS master", which can dissolve sodium hydrosulfite continuously in nitrogen gas atmosphere and can feed it to the pulp bleaching site was introduced. "HS master" was developed by Mitsubishi Gas Chemical.
　Concerning formamidine sulfinic acid, the "Fosble System" which is able to manufacture it on-site was introduced. The "Fosble System" was developed by Mitsubishi Gas Chemical.


For Expanding Use of Recycled Magazine Paper The Development of the Suitable Hot Melt Adhesives for Paper Recycling ?
Shigeru Yatsugi
Asahi Chemical Synthetic Co., Ltd.

　Recently, by amendment of the Law for Promotion of Utilization of Recyclable Resources (Recycling Law), the Paper Industry have become to have to develop the easy-recyclable products for the creation of a recycle-oriented society.
　The Plan " Recycle 60", that is, utilization rate of used papers will reach at least 60% by 2005 in Japan, is very difficult target. Because, Japan’s utilization rate of recovered paper is 57% in 2000, is among top in the world, and utilization rate for paperboard is nearly 90%, which is in a saturation level. But in a paper segment, utilization rate is only a little over 30%. Therefore the achievement of "Recycle 60" depends on increase in utilization rate of recycled magazine for paper, especially for printing and communication paper.
　In the field of recycled magazine, hot melt adhesives have been largely used because of excellent processability, but these hot melt adhesives have become to prevent paper recycling.
　Therefore, in order to promote the "Recyclable Paper Products Development and Promotion Project" under the supervision of the Ministry of International Trade and Industry, Japan Federation of Printing Industries which was entrusted by Paper Recycling Promotion Center, has organized the "Research Committee for Recyclable Paper Products", for the purpose of development promotion of easy-recyclable hot melt adhesives, and the committee has been reporting and researching the testing methods for easy-recyclable hot melt adhesives, and proposed the future trends.
　In this paper, we will report the classification of adhesives for bookbinding, mechanism of adhesion, and consideration of suitable hot melt adhesives for recycling.
　And also we will report the authorized convenient testing method (The First Stage Testing Method) to get a approval as Screenable Hot Melt Adhesives (EVA-based HMA) for paper recycling.


The Effects of Recycling on Pulp and Paper Properties
Takayuki Okayama

　Department of Environmental and Natural Resource Science, Tokyo University of Agriculture and Technology
The utilization rate of wastepaper in Japan has reached 58.0 % in 2001. However, the use for printing and communication papers has been limited due to concerns about appearance, strength and brightness. To promote the use of recovered paper for higher-quality grades, it is necessary to understand the fundamental aspects on recycled fiber. This paper describes papermaking potentials of recycled pulp fiber.
　When a kraft pulp is repeatedly defibrated in water, dewatered and dried for several times, the strength properties of papers, as well as the micro-structure of the pulp fibers, are considerably deteriorated. Morphological changes such as delamination and crack formation in cell wall of pulp fiber are enhanced by recycling treatment. On the other hand, the pore volume in cell wall of pulp fibers determined by the solute exclusion method decreases with recycling. Therefore, the shrinkage of internal pore structure under recycling is not easily reversed. The kraft pulp with a significant decrease in handsheet tensile strength during recycling tends to swell less and reduce their bonding potential.
　Variations in strength properties of papers during recycling are closely related to the fiber morphological characteristics. The fiber lumen diameter:fiber width ratio is an important predictive factor of strength properties of handsheet during recycling.
　Remarkable increase in water contact angle of kraft pulp fiber is observed by recycling. The recycled fiber is clearly much less hydrophilic than the virgin fiber. This relates to inactivation of the fiber surface by recycling, which is known as "irreversible hornification".
　The deterioration of neutralized recycled paper prepared from hardwood bleached kraft pulp by accelerated aging is similar to that of conventional neutralized paper.


Study of Deinking from the Point of View of "It is a Separation-Intensive Technology".
Takeshi Kanazawa
Aikawa Iron Work Co., Ltd.

　The deinking process, which was started as a substitute for mechanical pulp along with the energy-saving activity after the former oil crisis and enhancement of action for environmental protection in recent years, has made great strides to the white grade DIP production in place of Bleached Kraft Pulp recently.
　Differently from the waste paper treatment for paper board, the latest deinking process which requires high quality, becomes more complex in order to achieve complete ink detachment with the help of chemicals, removal of hard-to-deink material and stickies. As just described, by reason that technical investigation is necessary in wide-ranging fields, designing of deinking process has given a difficult image for us. In paper making industry, however, the recycling of waste paper stock have been approached since a long time ago by nature, so we can say that the deinking process is a product that has been built from accumulation of these technologies. It is possible to consolidate the process to three ones, that is Pulping, Contaminant Removal, and Upgrading. I think that deinking technology seems to be complicated but it will be understood relatively easy in bringing together these processes by the key word, "Specification Technology". With that, I will describe the latest technology of waste paper deinking on the basis of "Separation" in this study.


The Trend Japan has been Towards a Greater Use of Deinked Fiber for Producing Graphic Paper
Masakazu Eguchi
Stock preparation gr. Application Engineering Dept. Voith IHI Paper technology Co., Ltd.

　"Recycle 60" by 2005 was proposed by Japan Paper Association and Ministry of International Trade and Industry December 2000. The trend Japan, also worldwide in recent years has been towards a greater use of secondary fiber and higher recycling rates. This trend has been especially evident in deinking for graphic paper production.
　As recycling rates go up, it is expected the quality of the incoming furnish will decrease due to repeated recycling of the individual fibers and demands for high quality graphic paper from the consumer will put increasing demands upon deinking system.
　To meet theses increasing requirements, deinking technology continue to improve and advance in all areas including equipments design, systems, and chemistry. The following describes new deinking devices, technologies to help meet the challenges facing deinking system of the 2000s.
　The overall goal is to optimize the entire deinking system for more profitable operation.


Present Status of Paper Recycling and Future Subjects
Noboru Takeshita
Nippon Paper Industries Co., Ltd. R&D Planning Dept.

　Recently the utilization rate of used paper had been increasing dramatically, may achieve 58% in 2001. It was mainly due to decreasing in the market price of collected used paper because of increase in the collecting volume, the increasing cost difference with wood chip, the progressing of de-inking technology, and the stronger demand of recycle product at the market. De-inked pulp is likely to be used for wood free products today. At the poor market situation wood-free coated paper is decreasing in sales, however coated paper which contains recycled pulp has been sold 120 % over the last year. This trend will be continued.
　Comparing the energy consumption in the production process for each pulp, used energy of DIP was the lowest, but it came from only fossil fuels. On the other hand used energy of chemical pulp was bigger than that of DIP, but less fossil fuels consumed because some part of energy can be provided by itself.
　In order to construct recycling-oriented industry, it is necessary to set up and proceed the two recycling systems, namely a forest recycle to immobilize carbon dioxide and regenerate forest resources, and used paper recycle to save resources and energy.
　Japan Paper Association decided 60% as a target of utilization rate of waste paper in 2005. To achieve the figure, it is essential to cooperate between governments, related industries, and consumer. They should make efforts to use more recycle products, to achieve a preferable product quality, to collaborate a complete fractional recovery and an effective recycle system of office waste.


The LCI Calculation Method for LCA of Pulp and Paper Products
Shinji Nakayama, Tokiya Yaguchi
Pulp & Paper Research Laboratory, Oji Paper Co., LTD.

　We have been investgating about life cycle assesment (LCA) of pulp and paper products. In this investigation, we have been using to the caluculation of life cycle inventory (LCI) data for LCA from our mill operation data, our laboratory research data and the reference data. In this paper, we introduced firstry, some LCI data from reference literatures, and secondary, about our calulation method of accumulation from practical mill operation data, laboratory research data and some reference data. Finaly, we compared with LCI data about pulp and paper products of literatures and our caluculation results. In this comparison, we found there were neary equal results by our calulation method of accumulation and other methods.

Keywords : LCA, life cycle assessment, LCI, life cycle inventory, energy, CO2,NOx，SOx，pulp, paper, products


An Application of the X-ray Fluorescence Method to Quantification of Ink Printed on Paper Surfaces
Hitomi Hamada, Toshiharu Enomae, Masato Kato and Fumihiko Onabe
Graduate school of Agricultural and Life Sciences, The University of Tokyo

　With a view to quantify ink on nip-printed paper, the amount of which is unknown, a newly developed technique using an X-ray fluorescence method was applied. In this technique, the content of copper included in a cyan ink printed on paper was measured as an intensity of its peak in the X-ray fluorescence spectrum. Several kinds of paper were subjected to solid-printing using a universal printability tester with a cyan ink, and then the transferred ink amount was measured by weighing the ink roll before and after printing. The proportional relationship between the so measured copper content and the transferred ink amount measured gravimetrically was confirmed irrespective of the kinds of printing paper. This result suggests that the printed cyan ink amount can be determined by measuring the copper intensity in an X-ray fluorescence spectrum. Further, papers having several levels of smoothness were prepared with a supercalender. The transferred ink amount was found to decrease with increasing the smoothness of paper.
　The X-ray fluorescence method was compared with the method of print density calculated from lightness (L*). The coated papers containing the hollow or filled sphere pigments were prepared and solid-printings were conducted on the coated paper by an RI printing tester with a cyan ink. Lightness (L*) of printed surfaces of the coated papers was measured with a spectrophotometer. The print density was not proportional to the transferred ink amount measured by the X-ray fluorescence method, and was influenced by the lightness of unprinted surfaces. In application, the X-ray intensities of copper and coating components of the print with print mottle were measured and mapped using an X-ray fluorescence microanalyzer. For the poor print with print mottle, binder and pigment in the coating were distributed unevenly. This finding suggests that the print mottle may have been caused by the uneven distribution of binder and/or pigment in the coating.

Keywords: Lightness, Print mottle, Smoothness, Transferred ink amount, X-ray fluorescence method