Volume 09, Number 3
Oct 1996

Alkaline Sizing Applications Surge Ahead

Reprinted with permission from PIMA Magazine, April 1996, p. 14. The authors are principals of Paperfo, in San Francisco, CA (415-928-7297) .

North American paper and paperboard mills consumed more than $200 million of internal sizes in 1995. The paper industry has reaped tremendous efficiencies through alkaline fine papermaking conversions, reducing fiber and chemical consumption while improving paper's optical qualities.

The industry's application of sizing technology continues to evolve. Before 1985, only a few paper machines--many of them with European roots or innovators--were alkaline. As paper demand soared, non-integrated producers and fiber-troubled West Coast mills converted machines. By the end of the 1980s, record pulp prices propelled alkaline production of freesheet grades ahead of acid systems. Only OEM [office equipment manufacturers] paper specifications (such as office products machinery companies with explicit recommendations that certain types of paper be used in their machines) held back conversions at several mega-machines. The recession slowed conversions as pulp prices plummeted and interest in cheap fillers waned.

Producers of AKD [alkylketene dimer]sizing products--chiefly Hercules--prospered. In 1990, AKD was used for 90 percent of the alkaline-produced paper, and Hercules held 90 percent of AKD sales to paper mills in North America. Akzo Nobel/Eka Nobel provided some competition with the Compozil product line. By 1990, paper formed under alkaline conditions accounted for 70 percent of all freesheet production in North America (10.5 million tons).

ASA [alkenyl succinic anhydride] is completing the alkaline papermaking revolution. ASA sizing producers have successfully won over many of the machines producing paper to OEM specs--and several others--since 1993. ASA's fast, "on-machine" cure seems to be more popular than AKD's "cure in the roll" technology among reprographic and offset paper producers. Papermakers were once fearful of on-site emulsification and the highly reactive nature of ASA, but larger producers can now dedicate the resources to learn correct ASA application in exchange for more cost-effective sizing. Primary suppliers of ASA include Cytec Industries and Nalco Chemical Co.

Today, 90 percent of freesheet papers and 30 percent of coated groundwood papers are produced using alkaline wet-end chemistry. AKD still holds the higher market value share measured in dollars; it has a strong base of smaller mills where technical service people serve as process engineers and in other mills that favor site-ready chemical application. ASA holds the higher share of total market volume consumed. Acid rosin is used in mills where fiber is plentiful and chemistry requires simplicity. Neutral rosin has a few applications. The alkaline papermaking growth trend will now follow new machine production, increased filler use, and more demand for sizing among offset and desktop grades.

There are significant growth opportunities for internal synthetic size applications at paperboard mills. High quality board grades for printing are in demand and production is growing, especially in mills using secondary fiber. High pulp and wastepaper costs are also driving interest. Sizing chemical use has grown about 8 percent per year, eclipsing overall production fourfold since 1987.

For now, rosin remains the favored chemical in paperboard sizing applications. Many paperboard mills, particularly those making linerboard and kraft bag, produce rosin with spent pulping liquors. Conversely, milk carton and other SBS [southern bleached softwood] mills are the industry's largest consumers of synthetic sizes (especially AKD). Hercules is a leading supplier of other acid and alkaline size chemical applications in paperboard mills.

ASA is the fastest growing sizing agent in paperboard applications. Recycled paperboard has been growing at 10 percent per year since the late 1980s, and demand for fiber has been tight for some mills. Some have converted to alkaline, using ASA and starch to replace fiber or allow more fillers to come through pulping. Nalco [a supplier of papermaking chemicals] has been a leader in alkaline paperboard making.

[The Editor of PIMA Magazine added a note to this, saying that this report dealt only with internal sizing products, and that external sizes would be covered in a future column. Also: with regard to the last paragraph, in the seven or so months since this was written, demand for paper has slackened and the price of waste paper has fallen nearly to zero.]