JAPAN TAPPI JOURNALVol. 56, No. 7
July 2002 Abstracts
Outline of pulp manufacturing technology
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
The General Technology for Recycled Pulp
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
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
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
Foundation of Recycled Pulp Bleaching Technology
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 ?
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
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
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
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
Study of Deinking from the Point of View of "It is a Separation-Intensive Technology".
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
The Trend Japan has been Towards a Greater Use of Deinked Fiber for Producing Graphic Paper
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
Present Status of Paper Recycling and Future Subjects
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