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 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
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
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
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 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
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
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
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
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
Study of Deinking from the Point of View of "It is a Separation-Intensive
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
Stock preparation gr. Application Engineering Dept. Voith IHI Paper technology
"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,
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