TAPPI JOURNAL summaries.
TAPPI JOURNAL is a monthly publication that includes full-text, peer reviewed research papers exploring every aspect of pulp and papermaking. Each issue presents technically sound, applications based research; special insights from the authors; and more. TAPPI Membership includes access to all TAPPI JOURNAL content online at www.tappi.org. In addition, convenient print and electronic subscription options are available; TAPPI members receive substantial subscription discounts.
BEATING-INDUCED YELLOWING OF TCF- AND ECF-BLEACHED PULPS
APPLICATION: All pulps lose some brightness during beating, but TCF pulps tend to yellow more than ECF pulps, probably because ozone treatment does not effectively remove lignin-containing particles.
For environmental reasons, elemental chlorine-free (ECF) and totally chlorine-free (TCF) processes are replacing bleaching processes that use elemental chlorine. Various TCF- and ECF-bleached softwood and hardwood pulps were studied in this research on the development of optical properties and differences in color.
Yellowing occurred to some extent for all the different types of pulps studied. The researchers were able to detect characteristic differences in the optical properties of these pulps, which included kraft and acid sulfite pulps. Some were bleached in the laboratory, and some arrived as fully bleached industrial pulps.
The overall tendency of pulps to yellow has many possible causes. One prominent cause is the influence of the residues of shives and knots, which contain lignin and which tend to spread out over the fiber surfaces during beating. These detrimental particles are not removed by ozone treatment, which is a good reason not to use an ozone stage as the first stage in a TCF bleaching sequence. View this paper online at http://www.tappi.org/index.asp?pid=28428
At the time this work was done, Alexander A. Serkov was working with the Institute of Macromolecular Chemistry of Technical University of Darmstadt, Germany. Raimo Alen is a Professor at the University Of Jyvaskyla, Dept. of Chemistry, Jyvaskyla, Finland. Email Serkov at firstname.lastname@example.org.
AN INVESTIGATION OF LATEX PARTICLE CLUSTERING IN THE WET COATING COLOR
APPLICATION: The dispersion uniformity of the latex and pigment in the wet coating color can influence the degree of uniformity in the dry paper coating and correspondingly, in the commercial print.
In the preparation of wet coating colors, it is generally assumed that the dispersion of the solid components will be sufficiently uniform so as not to have a detrimental affect on the runnability or the end-use performance properties of the dried coating. The work in this paper showed that the dispersion uniformity in the wet coating color is not comparable for different coating colors and that there can be clustering or a non-uniform distribution of the latex particles with the pigment particles.
We investigated this clustering phenomeon using a specific low temperature microscopy analysis technique which consisted of cryogenic fixation, cryogenic slicing followed by the use of cryogenic Transmission Electron Microscopy for high resolution of the latex and pigment particles. This work also shows that the non-uniform distribution of the latex with the pigment in the wet coating color, upon drying, resulted in a non-uniform distribution of the latex and pigment in the dried coating structure. Upon printing this non-uniform coating structure on a commercial 6-color sheet-fed press, a high degree of print non-uniformity, in the form of back-trap mottle (BTM), was observed.
In this research we explain the different degrees of dispersion uniformity of the latex particles with the pigment particles using a proposed mechanism based upon thermodynamics. View this paper online at http://www.tappi.org/index.asp?pid=28429
Ronald L. Van Gilder is a scientist, Emulsion Polymers Research and Development, The Dow Chemical Company, Midland, Michigan, USA. Email Van Gilder at email@example.com.
ONLINE EXCLUSIVE INDUSTRY ANALYSIS
STUDY HIGHLIGHTS: 2001 U.S. AND CANADIAN PULP, PAPER, AND PACKAGING INDUSTRY PERFORMANCE REVIEW
APPLICATION: Comprehensive financial analysis can help professionals in the pulp, paper, and related industries gain understanding of the industries performance in a global context.
This is the seventh financial performance analysis of the North American pulp, paper, and packaging industry conducted by professors and graduate students at the University of Washington. This study analyzes the performance of all publicly traded U.S. (29) and Canadian (8) pulp, paper, and packaging firms, with pulp, paper, and packaging sales exceeding 20%, using data from 2001 and 2000 annual reports. Study variables include return on equity; earnings per share; total annual sales; global sales and production; capital expenditures and capital expenditure intensity; debt to equity ratios; and identification of product sector competitors.
The year 2001 was a challenge for the pulp, paper, and packaging industry in North America. Reasons for dampened financial performance include increased foreign competition, continued weakness in Asian economies that adversely affected sales volume and price, rising raw material and energy costs, and, for U.S. firms, export markets weakened by the strong U.S. dollar. View this paper online at http://www.tappi.org/index.asp?pid=28430
Dorothy Paun is associate professor at the University of Washington; Vivek Srivastava, John Garth, Karen Black, Andrew Dodd, Linda Nguyen, Indroneil Ganguly are M.S. students at the University of Washington; Elizabeth Scott is a Ph.D. student at the University of Washington; Jason Rice is a B.S. student at the University of Washington; and Hyun Deok Seok is senior fellow at the Korea Rural Economic Institute. Email Paun at firstname.lastname@example.org.
ONLINE EXCLUSIVE FRACTIONATION
OCC PULP FRACTIONATION-A COMPARATIVE STUDY OF FRACTIONATED AND UNFRACTIONATED STOCK
APPLICATION: Mills could save raw material, energy and capital by using this information.
A major focus of the work presented here is to assist in settling the ongoing debate about whether refined feed stock or recombined stock provides better strength properties for old corrugated container (OCC) pulp. We addressed the issue by comparing strength properties of stock from the two processes.
We determined optimum conditions for fractionating OCC pulp with a laboratory pressure screen and applied the findings in this study. The long fiber fraction was refined with a laboratory scale refiner and re-mixed with the short fiber fraction. We termed that furnish "recombined stock." The strength properties of the recombined stock (fractionated stock) were measured and compared with those of refined feed stock (unfractionated stock). We observed that the overall strength properties of refined feed stock are higher compared to the recombined stock. However, separate refining has brought savings in refining energy. View this paper online at http://www.tappi.org/index.asp?pid=28431
Mousa M. Nazhad is associate professor, Pulp and Paper Technology, Asian Institute of Technology, Sarin Sodtivarakul is assistant manager, Mahachai Kraft Paper Company Ltd., Ganjanaburi, Thailand. Email Nazhad at email@example.com.
CATIONIC LATEX AS A MULTIFUNCTIONAL WET-END ADDITIVE IN HIGHLY FILLED PAPER
APPLICATION: Cationic latex experimentally acts simultaneously as a retention aid, binder, and sizing agent when added to a mixture of pulp fibers and clay.
The use of cationic latexes for producing handsheets of low basis weight heavily loaded with clay is based on the the premise that the latex would promote clay retention, would reduce the debonding effect of filler particles, and would act as a sizing agent.
This study evaluated two experimental styrene/butadiene cationic latexes that differed in their charged groups (sulfonium and quaternary ammonium). We assume that cationic latex will work as a retention aid because of its positive charge, attracting it to the anionic fibers and the anionic clay. Thus, it may provide a bridge between the fiber and the clay particles and keep them together.
Latex enhances mechanical properties through bonding within the assembly of fibers and mineral particles. The latex particles deposited on all the components coalesce upon drying and form a polymeric film that acts as a binder. Latex in the filled sheet also contributes significant water resistance.
Handsheets prepared from a mixture of equal parts of clay and fiber and 1%, 3%, and 5% latex were tested for clay content, tensile strength and water absorptivity. The application of cationic latex effectively produced water-repellent handsheets with enhanced tensile strength that were heavily loaded with clay. Thus, cationic latex appears to be a multifunctional wet-end additive, acting as a retention aid, binder, and sizing agent simultaneously. View this paper online at http://www.tappi.org/index.asp?pid=28432
Bob Alince is senior scientist, Pulp and Paper Research Centre, McGill University3420 University Street, Montreal, QC, Canada H3A 2A7. Email Alince at firstname.lastname@example.org.
FORMATION OF PERACETIC ACID FROM HYDROGEN PEROXIDE AND PENTAACETYL GLUCOSE TO ACTIVATE OXYGEN DELIGNIFICATION
APPLICATION: A new method for generating peracetic acid may offer an alternative to commercial peroxy acids for pulp bleaching.
Peracetic acid can be used to activate oxygen delignification, but costs are high for this chemical that also can be hazardous to handle. A number of chemicals have been studied as peroxide activators in the effort to develop a peroxide-based approach. Among these, only TAED (tetraacetyl ethylenediamine) has found world-wide commercial application.
A new process in which peracetic acid is generated from the reaction of hydrogen peroxide and pentaacetyl glucose (PAG) may be an alternative to commercial peroxy acids for pulp bleaching. Under typical oxygen delignification conditions, peracetic acid is readily formed from the reaction of hydrogen peroxide with PAG.
This freshly prepared peracetic acid is effective in enhancing oxygen delignification. The researchers found that pulp four kappa number units lower than the control can be obtained when an acidified peracetic acid prepared by this method is applied to a kraft pulp in an OPaO sequence. The freshly prepared Pa was equally effective when applied to a sulfite pulp in a two-stage oxygen delignification process. View this paper online at http://www.tappi.org/index.asp?pid=28433
Guo Jun Kang and Yonghao Ni are with the Limerick Pulp and Paper Research and Education Center, University of New Brunswick, Frederiction, NB, E3B 6C2, Canada. Amir Malekian is with the Neil and Gunter, Dartmouth, NS. B3B 2C4, Canada. Email Ni at email@example.com.
EFFECT OF INCREASED JACK PINE CONTENT ON KRAFT PULP PROPERTIES
APPLICATION: As stands of jack pine are thinned, an anticipated increase of jack pine fiber in the furnish should increase the strength and freeness of the mill's kraft pulp.
At UPM-Kymmene Miramichi, jack pine constitutes approximately 5-10% of the total chip furnish. However, the mill is managing large forest stands of jack pine. The trees are at the right age to be cut, and the forests need to be thinned. Consequently, jack pine is expected to account for a larger percentage of the fiber furnish in the near future.
How will this change affect the kraft pulp? To answer this question, researchers pulped and bleached fiber furnishes with different amounts of jack pine and determined the strength properties of the pulps. They found that the kraft pulp strength increases with an increase in jack pine in the furnish. Under otherwise identical conditions, the pulp freeness is higher when jack pine is used in greater quantities. These results can be explained by the long fiber length and the coarseness of both juvenile and mature jack pine fibers. View this paper online at http://www.tappi.org/index.asp?pid=28434
At the time of this study, Carolyn Drost and Yonghao Ni were at the Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, New Brunswick, Canada. Drost is now at Great Northern Paper, Millinocket, Maine. Dale Shewchuk is with UPM-Kymmene Miramichi, Miramichi, New Brunswick. Email Ni at firstname.lastname@example.org
PREDICTION OF METALS DISTRIBUTION IN MILL PROCESSES, PART 1: Metals equilibrium model
APPLICATION: By combining equilibrium calculations with mill measurements, simulation can help to address practical mill issues and help us to understand metals distribution at real mill conditions.
This paper provides the basic equilibrium models for metals profile prediction in kraft pulp mills. Part 2 of this series demonstrates that metals profiles in fiber lines can be predicted by combining this equilibrium engine with existing process simulators. Part 3 of this series shows how nonprocess metals can be controlled and calculated in kraft mill chemical recovery systems.
This minimization re-energy method has been successfully applied to metals equilibrium calculations for pulp slurries. Pulp-bound metals, including calcium, magnesium, manganese, sodium, and potassium can be calculated by a free-energy minimization program, SOLGASWATER, from the proposed equilibrium models for pulp slurries, i.e. species and their formation constants. The effects of pH and diaminetriethylenepentaacetic acid (DTPA) on pulp-bound metals are also predicted from the model.
Temperature and ionic strength affect formation constants. For metals profile prediction in mill process, dissolved organics from kraft cooking have a significant role in keeping metals in the liquor. Unfortunately, the composition of dissolved organics from kraft cooking is very complicated and further study is needed to define species formed from metals and dissolved organics. In the current model, dissolved organics are represented by an equivalent univalent component. View this paper online at http://www.tappi.org/index.asp?pid=28435
Yongxiang Gu is with the Department of Food Science, Zhejiang University, China. Barry Malmberg, and Lou Edwards are with the Department of Chemical Engineering, University of Idaho, Moscow, Idaho, USA. Email Edwards at email@example.com.
IN THE FEBRUARY, 2004 ISSUE OF TAPPI JOURNAL:
A MATHEMATICAL METHOD FOR DETERMINING FIBER WALL THICKNESS AND FIBER WIDTH by Knut Roar Braaten and Dag Molteberg An accurate, cost-effective way to calculate the fiber cross-sectional dimensions can predict several of the properties of paper made from softwood kraft pulp. Through this research, an exact mathematical expression for fiber wall thickness and fiber diameter has been deduced for combining wood density and fiber coarseness, under the assumption that the density of the fiber wall is constant. The method was validated both by data found in the literature and data gathered from trials.
ARUNDO DONAX L. REED: NEW PERSPECTIVES FOR PULPING AND BLEACHING by Anatoly A. Shatalov and Helena Pereira This study focuses on ethanol reinforcement of alkaline pulping of the annual crop Arundo donax L. (giant reed). We examined the influence of process variables (ethanol and alkali concentration, liquor-to-reed ratio, time, temperature) on pulp yield and quality to identify optimal cooking conditions.
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RELATED ARTICLE: ATTENTION SUBSCRIBERS! ARE YOU MISSING SOMETHING?
If you have not renewed your TJ subscription for 2004, you will NOT be receiving the full-text version of any of the papers abstracted in this section. Many subscribers who have failed to renew have already received their final issue of TAPPI JOURNAL; for others, the January issue will be their final issue.
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For years, TAPPI members have asked for more full-text, peer-reviewed research in a convenient print format--and each month, TAPPI JOURNAL delivers. The January issue includes full text versions of most of the papers you see here, with the others available through www.tappi.org. I'm sure you won't want to miss it.
If you have already renewed your subscription by the time you read this notice, thank you! And don't worry--your subscription will continue. If you have not yet renewed your subscription to TAPPI JOURNAL, or if you would like to begin a new subscription, I urge you to do so immediately--a moment of your time now will ensure that you receive another year's worth of important research.
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|Publication:||Solutions - for People, Processes and Paper|
|Date:||Jan 1, 2004|
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