Single-species pulping: the world's preferred market pulps; 'outstanding attributes' are driving increased demand for single species pulps.

Mixed hardwood and mixed softwood pulp producer continue to lose ground to companies promoting single-species pulps. Increasingly, mixed-grade U. S. pulps (excluding diaper fluff) are now thought by many specialty paper producers to be less desirable and bought only for their often discounted prices rather than for any special attributes.

Instead, more papermakers are demanding single species pulps that unlike mixed species pulps, offer specific benefits and well-defined attributes. The movement toward single species pulps in the market pulp arena has been increasing in recent years as producers bring new "products" on to the market.

FEW ALTERNATIVES

Before the 1980s, global market pulp producers offered only two alternatives to traditional North American mixed hardwoods and softwoods: Scandinavian birch and Iberian eucalypts. Both were from naturally grown trees with widely varying harvest ages. Birch was a long (1.4 mm), slender, thin-walled fiber suitable for lightweight coated (LWC) and coated papers, but not for bulk sensitive grades, toothy finishes, or board grades. Iberian eucalyptus was over-aged and lacked any semblance of fiber-to-fiber uniformity.

North America was then producing two naturally grown, hardwood grades. Northeastern mixed hardwood was colt prised of short, relatively thin-fiber maple along with birch, beech, and poplar that exhibited a population of approximately 8 million fibers/g. Southern United States mills were producing a mixed hardwood consisting of oak, gum, ash, poplar, sycamore, maple, hickory, beech, magnolia, pecan, and perhaps six others. These fibers were relatively coarse with typical fiber diameters of 22-29 microns and fiber lengths varying from 1.0 mm to 1.7 mm for gum and sycamore.

These southern pulps had a relatively unimpressive population of 4 million fibers/g. This required papermakers to introduce at least 30% southern mixed hardwood pulp into an all softwood furnish for the sheet to begin to show any improvement in formation, opacity, surface smoothness, holdout, etc. The mixed northeastern hardwoods with their 8 million fibers/g had fibers whose diameters measured only 1922 microns with lengths of 1.0 mm for maple and beech up to 1.4 mm for birch.

HARDWOOD ADVANTAGES

Consequently, northeastern mixed hardwoods were valuable for their ability to produce a tighter, better formed, smoother sheet with little of the onerous vessel-segment picking that characterized the white oak portion of southern mixed hardwoods. Papermakers found that northeastern mixed hardwoods significantly improved softwood pulps at an addition rate of only 20%. As a result, producers of lightweight opaque sheets, Bible and hymnal paper, directory stock, and financial bonds specified northern hardwoods from Georgia Pacific, St. Arms, Thurso, and E.B. Eddy (now Domtar).

Throughout the 1970s and most of the 1980s, global customers accepted mixed hardwoods and softwoods because no major alternatives existed. Market pulp producers traditionally made "one size fits all" pulp grades. They did not engage in "target marketing" to search out and uncover unique pulp properties that might make their pulps particularly suitable to specific paper grades. They also did not divide their monthly production into customer-oriented "specialties" with properties such as high brightness, low dirt, high tensile, and low ash/ extractables.

As long as few alternatives existed, North American mixed hardwoods and softwoods were widely accepted and able to hold their own with normal market prices. A price differential between northern including Scandinavian birch and southern mixed hardwoods usually amounted to no more than US$ 10/a.d. metric ton. Some producers--Rayonier, Buckeye and Weyerhaeuser-Cosmopolis--made sophisticated pulp grades that had all the necessary benefits.

SINGULAR SENSATIONS

In the 1980s, the pulp market began to change. North American mixed hardwood and softwood producers found themselves at a distinct disadvantage. Traditional customers began to favor newer single-species pulps. Brazilian eucalyptus is the best example of a "new" pulp that offered papermakers outstanding advantages. This uniform, single-species pulp comes from plantation-grown trees. Superior seedlings and "cloned" trees produce harvestable fiber in 6-7 years.

Facial tissue producers such as Proctor & Gamble and Kimberly-Clark soon learned that Brazilian eucalypts had the unusual ability to produce tactile softness when layered on the surface. This quickly became the "outstanding attribute" of Brazilian eucalypts, and it found a niche market with facial tissue producers. Today, facial tissue is this pulp's major end-use application.

NEW IDEA FROM THE NORTH

The late 1980s and early 1990s saw the emergence of another single-species hardwood--aspen from mills in Alberta, Canada. Though naturally grown with considerable fiber-to-fiber variation, this single-species pulp quickly became popular among producers of coated paper seeking smoothness and coating holdout.

Because aspen fiber has a very low specific gravity with thin walls enclosing a large lumen, the fiber has little strength and is prone to collapse into a ribbon. This kept it from use in bulk-sensitive grades, but made it ideal for coated papers designed for gravure printing where smoothness is the most important quality. Coated paper producers (C1S label producers, for example) whose customers desired high degrees of printed gloss were quick to recognize that aspen was an ideal hardwood for those paper grades.

These Alberta mills have expanded their single-species pulp offerings by adding a bleached softwood kraft made entirely from white spruce, which is a thin-walled northern conifer pulp that refines easily and develops high tensile, fold, and burst strength. By contrast, southern U. S. softwood mills continue to use varying mixtures of loblolly, shortleaf, slash, longleaf, and sometimes Virginia pine with chips coming from both roundwood-a combination of juvenile and mature wood-and sawmill slabs that are 100% mature wood.

Exceptions include specialty mills and fluff pulp producers. These mills-predominately located in the southeastern U.S.-have learned to cultivate and cut only slash pine for their market pulps. Slash pine has an unusually high specific gravity and thick cell walls. This allows it to maintain its structural integrity and makes it ideal for filter media papers, latex saturated products, mercerization, and diaper fluff. United States mills using slash pine hold a dominant position in the global diaper fluff market producing more than 3 million metric tons annually with half exported to more than three dozen countries.

INDONESIAN ACACIA, CANADIAN MAPLE

The latest entry in the single-species hardwood pulp arena is Indonesian acacia. An earlier Indonesian market pulp from PT Riau Andalan was a mixed tropical hardwood containing 65-80 different hardwood species, it was unpopular and required heavy discounting. Later, PT' Kiani Kertas introduced an 80% Acacia mangium/20% Gmelina arborea Roxb. pulp with good uniformity. In 2000 PT Tel introduced a 100% A. mangium pulp. A. mangium quickly gained wide acceptance among producers of lightweight textbook papers, lightweight opaque printing grades, Bible paper, and other papers requiring low bulk and high opacity. This is an unusual blend of properties, but it has great value to certain mills.

These acacia pulps have unusually high populations of 18-23 million fibers/g. This reflects a wide variation in fiber lengths and diameters. Brazilian eucalypts, for example, exhibits strong uniformity in fiber dimensions with the vast majority of fibers measuring 0.95 mm by 16 microns in diameter. Natural growth aspen by contrast has fibers that vary from 0.7 mm all the way to 1.2 mm and diameters that vary from 14 microns to almost 20 microns.

Not to be outdone, eastern Canadian mills, along with Domtar's mill in Woodland, Maine, USA, and International Paper's Quinnesec, Michigan, mill began to move toward the selective harvesting of only maple trees so they could promote "high maple hardwoods." In the middle 1980s, these pulps were only 50%-60% maple. Mills then ratcheted Up to 80% and later to 90% maple. Today, five northern hardwood mills can boast that their hardwood pulp is "predominantly maple." Domtar's Espanola mill has three hardwood grades that are 100% maple, 100% birch, and 100% aspen, respectively.

FIBER OF THE FUTURE

Single species pulps clearly are the fiber of the future. As the choice and quality of these pulps continues to grow, they are fast becoming the preferred fiber source for papermakers around the world. However, mills and their pulp suppliers must clearly define the target pulp's outstanding attributes, unusual properties and (if any) unique or distinctive characteristics. Knowing this will help determine what category of paper grades in which to use a single species pulp.

Finally, paper mills must work closely with their customers to identify each grade's "prime requisite" or most essential property. Paper mills can then strategically target the best mix of pulp and papermaking technology needed to deliver superior products. S!

Table 1: Single species pulp producers, species, attributes, and most
appropriate applications

Country            Major producers             Species

Indonesia          PT Tel, PT Riau Andulan     acacia
                   PT Kiani Kertas
Brazil             Aracruz, Klabin-Riocell     Eucalyptus
                   Cenibra, Bahia Sul, Jari    grandisflora
Canada             AIPac, DMI, Domtar          aspen

Canada             Domtar, Irving              maple

Spain, Portugal,   ENCE, Portucel, Phoenix     Eucalyptus
Chile, Thailand    CMPC, Santa Fe              globulus

Sweden,            major pulp producers        birch
Finland, Canada

Chile              CMPC/Arauco                 radiata pine

Canada             DMI, AIPac                  white spruce

Canada             Domtar, Abitibi-Cons.       Black spruce

Major producers           Attributes            Major applications

PT Tel, PT Riau Andulan   high opacity, low     Bible/hymnal paper,
                          bulk                  textbook

PT Kiani Kertas           very high             Int'l directory,
                          population            financial prospectus

Aracruz, Klabin-Riocell   bulk, opacity, high   facial tissue, printing
Cenibra, Bahia Sul,       population, tactile   papers filters,
Jari                      smoothness            specialty products

AIPac, DMI, Domtar        high smoothness,      coated papers,
                          holdout               especially gravure

Domtar, Irving            high population,      printing/writing grades
                          Thick walls           resists abuse of
                                                refining
ENCE, Portucel, Phoenix   endures abuse of      toweling, tissue,
CMPC, Santa Fe            joint re-refining,    coated and uncoated
                          Papermaking           printing papers

major pulp producers      long/slender          LWC, coated/uncoated
                          fibers, refines       printing papers
                          easily, strength,
                          entanglement

CMPC/Arauco               thick-walled          cement reinforcing,
                          fibers, good blend    packaging papers
                          of tear, fold,
                          burst, tensile

DMI, AIPac                thin-walled, easy     printing, converting
                          refining low          papers smooth surfaced
                          coarseness            grades

Domtar, Abitibi-Cons.     thin-walled, easy     facial tissue,
                          refining low          toweling
                          coarseness            printing/writing grades

Author's Note: Our apologies to those companies omitted due to space
limitations

IN THIS ARTICLE, YOU WILL LEARN:

* How pulp markets have change since the 1980s

* Advantages offered by single species pulps

* The fiber attributes that give various pulps their distinct characteristics

ADDITIONAL RESOURCES:

* For information about TAPPI's pulping discussion boards, committee and events, go to www.tappi.org and click on the words "pulp/wood products" beneath the TAPPI logo

About the author: David C, Hillman is marker pulp consultant based in Erie, Pennsylvania, USA. A graduate of Georgia Tech, Hillman, worked for 17 years at Westvaco's Luke, Maryland, mill; Wick/fife, Kentucky, mill; and in the New York corporate office. From 1981 to 1982, Hillman was vice president/specialty sales for Woodpulp International and from 1982 to 1987 was manager of pulp sales for Hammermill. In 1987, he became a market pulp consultant and has worked with more than 100 pulp and pager companies. Contact him by email et [e-mail] or by phone at [phone].