2002 Apr JAPAN TAPPI JOURNAL

 

JAPAN TAPPI JOURNALVol. 56, No. 4

April 2002 Abstracts


A Laboratory Study of Damaged Wastepaper
Fumihiko Mukae, Junta Egawa, Masanori Nikaido and Atsushi Yamasaki
LION Corporation

 Wastepapers turn yellowish-colored and damaged when exposed to UV light and kept at high temperature during summer. When the damaged wastepapers are used as raw material, the quality of recycled paper becomes remarkably inferior. Generally, paper mills try to suppress the effect of damaged wastepapers to quality by increasing the amount of chemical used during process, especially increasing the amount of hydrogen peroxide is quite common.
There are two possible factors for the quality deterioration by using these wastes.
a) Adhesion of ink to fiber: Ink removal efficiency becomes low.
b) Increase of fine inks: Ink collection efficiency becomes low.
In this presentation, the cause of damaged wastepaper deterioration and solutions for suppressing its effect to the quality of recycled paper are discussed.


What Papermakers Need to Know
Where to get Environmentally Approved, Quality Fibre
Allan G. Jamieson
AOK Innovations Pty. Ltd.

 It has been shown that the papermaking quality of wood supplied to an integrated fine paper mill is of more economic importance to the mill than is the price paid for the wood. Papermakers, therefore, should take close interest in defining specific technical quality requirements for fibre raw material. It is now evident, though, that it is also necessary for the papermaker to ensure that the raw material has suitable environmental credentials, i.e., that it is obtained from a resource that is managed in a fully sustainable manner: Sustainable not only ecologically but also in the context of economical viability and social desirability.
 This paper examines two emerging man-made forest resources in Tasmania; "seedling" plantations and "seed" plantations (also called regrowth forest). It is concluded that Tasmania can supply high quality pulpwood fibre possessing excellent environmental credentials.


Scale Deposit Problems and their Contorol in ECF Bleach Plants
Hirotaka Tanabe
Yokkaichi laboratory, Hakuto Co.,Ltd.

 Technologies of kraft pulp bleaching have been greatly developed in recent years because of environmental consideration. New ways of bleaching are ECF and TCF bleaching. ECF bleaching does not use both elemental chlorine and hypo chloride, and TCF bleaching does not use chlorine compounds at all. In Europe and U.S, almost pulp plants have completed to change their bleaching ways to ECF or TCF. Many pulp plants in Japan are also trying to change to ECF bleaching.
 Basically, scale deposit problems often occur in bleaching plants. In order to apply ECF bleaching and to promote a closure of process water, the tendency of scale problems in ECF bleaching comes to be one of the most important concerns.
 In this report, we showed characteristics and control methods on calcium oxalate and barium sulfate scale which should be especially considered for ECF bleaching.


Advanced Spray Coating Technology- OptiSpray ?
Vilho Nissinen
Metso Paper, Inc., Finland
Hidehiko Yamazaki
Metso Paper KK

 Over time we have seen a decrease in the trend of paper product prices. In recessionary times, low value products lose their profit marginal quite easily. To achieve good profitability, the value of the product must increase while at the same time production costs decrease. The dream of every papermaker is to produce a high-value product with economic raw materials while maintaining good runnability at high speeds.
 The demand for lower impact in the paper coating process is well known, as are the difficulties in blade coating. Film transfer technology has taken a big step in the right direction. The weaker base papers can be coated. Still there is heavy web contact with many dependencies and interactions between coater and paper in the film transfer nip. The coat weight variations caused by unevenness of the base paper and changes in the cross directional tensile profile over the coater are ready examples.
 Thanks to film transfer technology, the coated and improved newspaper grades are already available. With the help of an improved print image, four-color newspaper printing will gradually attract the commercial advertising business. Even traditional newspapers will be four-color printed on light-weight coated news grade, making them as attractive for product advertising as the newspaper inserts are today. Every cold-set newspaper printing house is seeking business use for available day time hours.
 Now, Metso Paper launched its new OptiSpray technology. The OptiSpray coating process is based on a controlled, high-pressure spray application of coating or surface size directly onto the surface of the paper or board, without any direct machine contact. The coating is simultaneously sprayed at high speed on both sides of the paper web. OptiSpray achieves excellent coverage of the base paper.


The Development of New High Speed Paper Machine Series
Akihito Nagano
Mitsubishi Heavy Industries, LTD, Paper & Printing Machinery Division

 A new Mitsubishi high-speed paper machine development project has started in 1999 and concluded with product offering to the market in October 2001. The new product is known as MJ series and is designed to complement the current MH series Mitsubishi paper machines.
 The goal of MJ series paper machine is to produce quality paper at 2000 m/min operation speed while being an operator friendly product. The MJ series has been developed in the course of the intensive elementary study, program simulation, model test, and final verification on our pilot paper machine in Mitsubishi R&D center of Mihara, Japan.
 This paper presents the concept and features of the MJ series paper machine.


Drainage of Forming Part−V.I.D. Formation System−
Kazunori Nagatomo
Kobayashi Engineering Works, LTD.
Licenser AES Engineered Systems(U.S.A.)

 Various types of gravity and vacuum augmented foils have been used as typical drainage equipment for conventional Fourdrinier machines.
 In any type of drainage equipment, filtration mat formed in the early stage of drainage is a limiting factor for the drainage efficiency in the later stage. When we call this dewatering process as "filtration drainage", paper makers already have made the possible efforts to overcome the negative effects of "filtration drainage". It seems that the efficiency of conventional drainage equipment has reached its limit.


This paper deal with a device, V.I.D. technology with its thickening drainage process, which has been developed to provide the solutions for various issues of conventional forming Application of DIA-BIOFRINGE to the Treatment of Paper Mill
Wastewater
Hisao Murakami and Katsumi Sone
TOKAI PULP & PAPER CO.,LTD.
Yasuyuki Takagawa
MITSUBISHI KAKOKI KAISHA,LTD.

 The DIA-BIOFRINGE, an aerobic biofilm system which uses strings with ribbons fixed to the metal frames and swaying in the water are used as biofilm media, has many advantages such as no backwash operation required, quick startup, and flexibilities in reactor design.
 TOKAI PULP & PAPER CO.,LTD. recently introduced the DIA-BIOFRINGE into their wastewater treatment plant to treat paper mill wastewater. In the demonstration test carried out prior to its construction, a stable BOD removal have been obtained at the BOD backfill volumetric loading of 1.5 kg-BOD/m3・day. Furthermore, it was confirmed at the test that preliminary SS removal, usually necessary in ordinary biofilm systems, are unnecessary. Thus, the introduction of the DIA-BIOFRINGE is proved to be very advantageous from the fact that the system is totally simplified and small investment in auxiliary units of the system.
 technology. Examples of its field applications are also given.


Introduction of EBARA Water and Heat Recycling Systems
Yuji Tsukamoto
Ebara Corporation , Environmental Engineering Group

 Based on its long experience and advanced technology, EBARA CORPORATION has proposed and delivered mainly to the industry of foods and drinks EBARA water and heat recycling systems which combine thorough on-site surveys with profound water and wastewater technology and energy saving technology and take into consideration even the production lines. In these water and heat recycling systems, the wastewater and the waste heat, which were used on a one-time use basis and discarded in the past, are regarded as "Renewable resources", that is, these wastes are treated by the optimum renewal technology for reuse or cyclic use. This can not only reduce the loading on the environment but also contribute to reducing the water and vapor to be used in the plant. The results have already been highly evaluated, and we started in the last year to propose these systems to the pulp and paper industry. At this opportunity, we would like to introduce our water and heat recycling systems.


Conversion to ECF Bleaching−A Comparative Study with Focus on the First Bleaching Stage
Martin Ragnar
Kvaerner Pulping AB, Sweden
Marcelo Moreira Leite
Kvaerner do Brasil Ltda., Brazil
(Translated) Michio Imai
Kvaerner Pulping KK

 In the present paper, an investigation of some different ECF bleaching sequence is presented, and the results compared. Special attention is paid to the importance of the first bleaching stage after oxygen delignification, i.e. the so-called delignifying bleaching stage. Two different mill-oxygen-delignified HW kraft pulps were subjected to a number of different bleaching sequences. The first pulp was bleached according to D(EO)D, D*(EO)D, (ZD)(EO)D, Z(EO)D and after interpolation evaluated at 89% ISO brightness, and the second pulp according to D(EP)D, D*(EP)D, (ZD)(EP)D, A*ZD(EP)D and after interpolation evaluated at 87% ISO brightness. The "*" here denotes a treatment at high temperature and log retention time. Both the use of D* and Z efficiently reduced the yellowing tendency of the pulps when compared to the conventional D-based ECF sequences. Based on the laboratory trials, consumption figures were adjusted to reflect mill operating conditions and the differences in operational costs between the different sequences were calculated. The sequences with D* were economically very attractive, showing high savings in operational costs compared to the reference D(EO)D and D(EP)D sequences, especially when the target brightness was somewhat higher, i.e. 89%. Considering the unit costs, the required investments needed for Z-based sequences were found to be difficult to justify, especially when the target brightness is somewhat lower, e.g. 87% ISO.

Keywords
hardwood, Eucalyptus, ECF bleaching, chlorine dioxide, hydrogen peroxide, ozone, hot acid treatment, hexenuronic acid, brightness reversion


Sectioning Technology of Papers for Observation and Analysis by Using OM, SEM and EPMA
(1)Sectioning Technology for Optical Microscopy
Tadahira Hamada

 In order to obtain the information about inner structure of papers being concerned in production, development and printing of papers, observation and analysis of paper sections by using OM, SEM and EPMA are very effective means.
In this paper, sectioning techniques for optical microscopy were descrived.
Many sectioning techniques have been developed to obtain sections without serious artifacts such as the damage of fine structure and breakdown of section during sectioning and following preparations. In observation by opyical microscope, the specimens are desirable to be sectioned as this as 1〜10μm in thickness, so embedding of specimen using plastics such as methacrylate resin, epoxy resin and so on before sectioning is usually essential to prevent such artifacts.
 Cross section which is cut at right angles to the plane of the paper is widely utilized to observe paper structure in thickness direction but it is only representative of a minute portion of the specimen. To improve the disadvantage of cross sectioning, oblique and parallel sectioning were introduced.
 The former is carried out by cutting at a small angle to the plane through the paper, the latter is carried out dividing the specimen to several layers parallel to the plane of the paper. The information of wider area can be obtained by these procedures.


Effect of Blending Ratio of Amphoteric and Anionic Latex on Print Quality of Coated Paper
Yong-Kyu Lee and Kyu-Jae Park
Department of Paper Science & Engineering, College of Forestry Science, Kangwon National
University, Korea 200-701
Shigenori Kuga
Department of Biomaterials Science, Graduate School of Agriculture and Life Sciences, The University of Tokyo

 Effectiveness of amphoteric latexes was studied to solve the problems of binder migration and uneven binder distribution in coating layers. The addition of amphoteric latex was effective in improving rheological properties of coating color in alkaline region through strong interaction with other coating components. As a result, coated papers made with amphoteric latex showed better printing qualities, such as paper gloss and surface smoothness.

Keyword :Amphoteric latex, Binder migration, Rheological property, Coated paper,Printing quality


Methodology to Use Flatbed Image Scanner for Formation Analysis of Paper
Toshiharu Enomae and Shigenori Kuga
Graduate School of Agricultural and Life Sciences
The University of Tokyo

 Abstract
 Versatility of a desktop flatbed image scanner with a transparency unit as an image input device for formation analyses is exhibited and discussed. Optical density of scanner output is defined as the logarithm of the ratio of gray level in full transmission with no material to that at a given site (pixel) of a sample. Optical density of the scanner output under satisfied prerequisite conditions showed an excellent agreement with that of Elrepho type reflectometer and the pre-calibrated values noted on a standard film though the proportional constant is reduced from 1 due to aged deterioration of the light source after 1 year, maintaining linearity. For stacked paper sheets, however, there remains distortion in the output characteristics, that is, non-linearity even after the calibration. So, unlike Elrepho type, optical density squared is empirically almost proportional to the basis weight of paper. In application, formation of handsheets loaded with calcium carbonate from softwood and hardwood pulps at different retention times is quantitatively analyzed with the light transmission images obtained by the scanner. The formation index, the standard deviation of optical density squared correlated better with the subjective ranking by 6 panelists than that of optical density or of gray level. Optical density squared divided by the basis weight shows the highest Kendall's coefficient of correlation. In summary, the standard deviation of gray level is found to lack in validity as a formation index except comparison between papers with close gray levels.

Keywords:Formation index, Gray level, Light transmission image, Optical density, Subjective ranking