Literature

"Microbial Challenges Unique to Closed Recycle Paper Systems," by L.R. Robertson and W.R. Schwingel. Wet End Chemistry Conference and COST Workshop, Gatwick, UK, 28-29 May 1997, Paper 19, 17 pp. £95 from PIRA International. (PB Abstract 6804, 1997)

Problems caused by unchecked microbial growth in closed water systems include spoilage of additives, loss of fiber strength and brightness, odors in paper, formation of toxic or explosive gases and possible corrosion of mild steel. Biocides which are suitable for open systems may no longer be applicable in closed systems. The authors discuss a simulated mill closure and methods that can sometimes identify the degree of closure.

"Simple Method to Determine the Photoyellowing of Papers," by R.S. Pereira and J.M. Neves. Papel v.58 #8, pp. 77-83 (in Portuguese) (PB Abstract 1368, 1998)

A quick, easy and relatively cheap method is proposed for quantifying yellowing in cellulose pulp and paper, especially paper made from high yield pulp. The TAPPI test for color reversion of bleached pulp was used, and an apparatus based on the Chromato-Vue 70G was constructed for the photochemical tests. The authors say the studies showed that "photoyellowing could be used to differentiate the permanence characteristics of paper."

"Isolation of Enzymes to Depress Light-Induced Color Reversion of Mechanical Pulps," by T. Itoh et al. 1997 (64th) Pulp & Paper Research Conference, Tokyo, 19-20 June 1997, pp. 96-101. Tokyo: Japan TAPPI, 1997 (in Japanese) (PB Abstract 9484, 1997)

Fourteen fungi that could depress light-induced color reversion in mechanical pulps were identified, and three of these were particularly effective. One of the fractions from one of the best fungi's extracellular crude enzymes suppressed 70% of the color reversion in the mechanical pulp samples tested. 3B1.8

"E-Beam Equipment and Applications," by D.A. Meskan and A.F. Klein. RadTech Europe 97, Lyon, France, 16-18 June 1997, pp. 114-121. Nyon, Switzerland: RadTech Europe, 1997, SFr 150.00. (PB Abstract 1305, 1998)

Electron beam chemistry and e-beam processing technology have advanced rapidly and applications have grown: curing of printing inks, coatings and adhesives; film cross linking; and sterilization. The authors describe installations worldwide and predict a bright economic future for the process.

"STFI Starts High Risk Project," by N. Lindstrand. Svensk Papperstidn. v. 100 #10, Oct-Nov. 1997, pp. 26-28. (In Swedish) (PB Abstract 1254, 1998)

Impulse technology is the brief exposure of paper to temperatures of up to 350°C, which gives it completely new properties. The surface is softened and becomes smooth and sealed. The Swedish Pulp and Paper Institute (STFI) has completely rebuilt a paper machine for a 15-million-kronor/year research project on this technology.

"The Effect of Fines on Fiber Bonding: Cross-Sectional Dimensions of TMP Fibers at Potential Bonding Sites," by P.A. Moss and E. Retulainen. J. Pulp Pap. Sci. v.23 #8, Aug. 1997, pp. J382-J388. (PB Abstract 9270, 1997)

Handsheets made from the long fiber fraction of a pulp can be made denser and stronger if chemical or mechanical fines are added. Kraft fines made the sheets stronger than TMP fines did. [The 1980 Dictionary of Paper says that fines are "very short pulp fibers or fiber fragments and ray cells."] The authors concluded that fines addition helps to bring fibers into close contact, thus facilitating bonding.

"Chemistry of Wet Strengthening Paper: Trends, Recent Developments and Applications," by M. Crisp. Wet End Chemistry Conference and COST Workshop, Gatwick, UK, 28-29 May 1997, Paper 4, 19pp. PIRA International, 1997, £95. (PB Abstract 6642, 1997)

The history of water soluble synthetic polymers used as wet strength additives is traced through the use of polyurea (UF), polymelamine (MF), polyaminoamide-epichlorohydrin (PAE) resins, glyoxalated polyacrylamide resins, amine polymers, resins based on epichlorohydrin and polyaminoamidepolyurelyene, polyethyleneimine and dialdehyde starch. In the last decade, environmental pressures have made formaldehyde (in UF and MF) unpopular; a more environmentally acceptable form of PAE and chlorine-free additives has been developed. The mechanism, evaluation and application of wet strength resins are discussed.

"Synthetic Papers--A Review," by G.D. Agrawal and S. Mannar Mannan. Packag. India v.29 #6, Feb-Mar. 1997, p. 23 ff. (PB Abstract 1463, 1997)

Manufacturers are listed, as well as the properties of five synthetic papers (Cosmo, Yupo, Toyobo, Tyvek and Teslin). Manufacturing may be by a blown or cast process, and fibers can be laid by monoaxial or biaxial orientation and then stretched and coated. Spunbonding is the process used for nonwovens. Techniques for printing on synthetic paper are briefly discussed.

"Don't Underestimate the Power of the Polymer," by N.-O. Bergh. Pulp Pap. Eur. v.2 #9, Nov. 1997, pp. 13-15. (PB Abstract 1173, 1998)

Latices used in paper coatings are produced by a complex polymerization process with additives that include modifiers, surfactants and initiators. Modifiers include vinyl acids, vinyl hydroxyl monomers, unsaturated amines and amides.

"Paper Clips" is a set of 25 slides accompanied by a detailed script, for use in classroom presentations to audiences of all ages. It covers the history of paper, paper manufacture, environmental stewardship and modern industry careers. $25 from TAPPI's Public Outreach Department (800/291-3145).

Paper Buyers' Encyclopedia, 1998/99 ed. This directory of papers for the paper and graphic arts industry incorporates for the first time a section on importers and exporters, with country and product information. For each of 5500 mill and private brands, it provides a great deal of information, including whether it is alkaline or not, or available in colors, and much more. All papers are grouped by brightness and opacity into grade number and function categories (e.g., No. 1 Xerographic), and well indexed, with a great deal of supplementary information. Available on disk for $150. The book is $110. Order on the Web, at www.gradefinders.com, or by e-mail, info@gradefinders.com; or write to Gradefinders at 662 Exton Commons, Exton, PA 19341 (610/524-7070, fax 610/524-8912).

"Retention of Calcium Carbonate during Recycling: Direct Loading Versus Fiber Loading," by J.H. Klungness, M.S. Sykes and S. Aziz. Environmental conference and exhibit, Minneapolis, 5-7 May 1997, Book 1, pp. 497-503. (PB Abstract 7079, 1997)

When calcium carbonate is added to the furnish by forming it within the lumen of fibers, rather than adding it between the fibers, more of it stays inside the fiber when it is recycled, and 50% less filler leaves the mill in sludge.

"Impact of Pulp Chemical Composition on Recycling," by B. Cao, U. Tschirner and S. Ramaswamy. 1997 Pulping conference, San Francisco, CA, 19-23 Oct. 1997, Book 2, pp. 1081-1096. TAPPI Press, 1997, 2 v. $104.50) (PB Abstract 1910, 1998)

For western hemlock, the amount of pentosan in the fibers, especially xylan, has an important effect on their recyclability. The higher the xylan content, the greater the recyclability; but neither the lignin content nor the interaction between pentosan and lignin made a difference. The authors explained this effect in terms of xylan molecules preventing neighboring microfibrils from developing close association with each other with a resultant loss in wet fiber flexibility.

"Fine Paper Properties and the Effects of Wet-end Starch When Using Deinked Recycled Fiber in an Alkaline System," by B.J. Hipple. A TAPPI Press anthology of published papers 1992-97, Ch. 5, pp. 438-443. (Atlanta: TAPPI Press, 1997. $76) (PB Abstract 2169, 1998)

The strength of paper made from four fiber sources was tested: virgin pulp, two recycled pulps, and deinked recycled pulp. To make recycled papers as strong as the paper made from virgin fiber, large doses of starch were needed; however, high levels of cationic starch may cause problems in the system and a loss of internal sizing, especially if there is a high level of anionic material in the recycled pulp. Wet end starch substitution may need to be adjusted to reach comparable strengths in recycled paper.

"Non-Wood Fibers in Papermaking. Literature Review," by A. Leminen et al. Research Notes 1779, Espoo, Finland: Technical Research Center of Finland, 1996, 34 pp. FIM [Finnish Marks] 125. (ISBN 951-38-4974-0) (PB Abstract 8246, 1997)

At present, 8% of the world's total paper and pulp production comes from nonwood fibers. Most of this takes place in China and India, but some is in North America and the EU. The most common plants used as fiber resources are reviewed, and technical pulping alternatives are discussed.

"World Novelty 'Paper from Hemp' - Neusiedler AG" (Anon.) Pap. Osterreich #4, 1997, pp. 26-27. (In German) (PB Abstract 6894, 1997)

Neusiedler Aktiengesellschaft Austria, has been developing the use of hemp for paper production since 1996, when its Kematen mill started to produce the world's first totally chlorine free (TCF) bleached pulp made from 30% hemp and 70% woodchips. It is marketed as Hemptec, a high quality office stationery, and will soon be sold internationally. Austria currently [mid-1997] grows about 900 hectares of hemp.

"Wet-Strength Resins in Hygienic Paper Production," by U. Hamm. Papier v.51 #6A, June 1997, pp. V118-V123, paper presented at 26th EUCEPA conference together with Zellcheming annual meeting, Baden-Baden, 23-26 June 1997. (In German) (PB Abstract 7477, 1997)

Wet strength additives are used in the production of sanitary and household paper. The two main types are urea formaldehyde and melamine formaldehyde, which account for 63% of wet strength chemicals; and epichlorohydrin, which makes up 33%. Use of wet strength resins leads to chlorine-containing compounds in the effluent; research to develop less polluting compounds is ongoing.

"Paper Sludge: Sowing What We Reap," by M. Dacomb. Managing Environmental Effects: PITA Environmental Seminar, Chorley, UK, 13 May 1997, 10pp. (Bury, UK: Paper Industry Technical Association, 1997) £50. (PB Abstract 1487, 1998)

Paper mill sludge from treated effluent, flocculated with polyacrylamide, composts well and is being added to organic waste for use as a general fertilizer by Eco-Sci. It works even during dry summers, because it holds the moisture so well.