Natural chemical additives have played an important role in the raw material prep¬aration stage since the earliest beginnings of handmade papermaking more than two thousand years ago. Up to the end of the eighteenth century, chemical ad¬ditives from natural resources were used to increase paper strength, to generate better writing and printing characteristics, to enhance paper brightness, and to color it.
With the invention of the papermaking machine, chemicals began to con¬tribute to industrial papermaking processes. It was only when newly developed bleaching chemicals came into use that wood pulp as a new source of raw material could be exploited to the full. The chemical additives assisted the automation and productivity of the papermaking process as well as the enhancement of paper quality and thus contributed to a large degree to the growth of the paper industry in the first half of the twentieth century.
The past 50 years have been characterized by the increased use of recovered paper and white natural pigments as fillers and for paper coating, as raw materials, by an ongoing improvement of the paper machine productivity, and an emphasis on economics, ecology and quality. All this has been, and still is, supported by chemical additives and their creative application.
On a global view, paper and board today consist of nearly 99 % natural materials: Virgin fibers from chemical and mechanical pulps contribute 48 % of the total raw material consumption; recycled fibers 40 %; non-fiber material as fillers and coat¬ing pigments 9 % with the remaining 3 % being “chemical additives” (solid materi¬als). In addition, 3 % of so-called basic and bleaching chemicals are added, mainly in the production of chemical, mechanical and deinked pulps (Fig. 3.1). These chem¬icals do not remain in the pulp (they are decomposed and are contained in the cooking liquor and the untreated waste water) and thus do not appear in the paper but they are a significant factor in production costs (Fig. 3.2).
By mass starch ac¬counts for 1.7 % of the world paper production, which is more than 50 % of all chemical additives. Traditional papermaking chemicals such as aluminum sulfate and nowadays other aluminum compounds are still used at a rate of 0.3 % on paper, 10 % of the total dry based mass of chemical additives. Pure synthetic chemicals – called “specialty chemicals” – account for only 1 %, relative to the paper and board production. The market for chemical additives is currently estimated at 17 billion € worldwide. 28 % of this is basic and bleaching chemicals, mainly used in the production of pulp and 72 % is chemical additives used in the production of paper and board. On average, chemical additives account for approximately 5 % of the cost of the finished paper and board, varying for the individual paper and board grades.
The wide variety of specific demands that are placed on the different paper and board grades cannot be fulfilled with natural raw materials alone. It needs chem¬ical additives with very specific performances, the so-called “specialty chemicals”, and their intelligent application. Some of these additives are used in order to ob¬tain certain properties of the finished paper e. g. colored sheets, resistance against ink or water, high gloss, good and appealing printability or high strength for pack¬aging. This group of chemical additives is called “functional chemicals”. Other chemical additives are used to solve or prevent problems in the paper manufactur¬ing process, to improve the efficiency of the production process and/or to protect the environment. The latter type of additives for instance helps to reduce the con¬sumption of fresh water and energy, prevent foam and deposits, improve drainage or reduce fiber loss. This second group of additives is called “process chemicals”