Abstract

The process of paper formation involves dewatering an aqueous fibrous suspension, followed by drying. In most cases, the fibers are cellulosic, and paper’s strength is primarily due to hydrogen bond formation. The term paperboard is used in cases where the product is relatively thick and less flexible. In addition to fibers, modern paper often contains substantial amounts of minerals, such as calcium carbonate or kaolin clay. Other components, usually at lesser quantities, can include starch, modified starch products, synthetic polyelectrolytes, and a variety of other additives.

Though there is a tradition of hand-made papermaking, going back almost two millennia, most modern paper is manufactured on large, highly automated machines. The fiber slurry is formed and dewatered on a continuous fabric screen or sandwiched between a pair of such screens. Though most of the water used in this process is recycled multiple times, the paper industry remains a major user of fresh water. Substantial gains have been achieved to minimize the loss of fibers and other solid components from the process. Likewise, progress has been achieved in reducing the amount of energy expended in the drying of paper, primarily through increases in the proportion of water that is removed by pressing, rather than evaporation.

After reviewing paper’s distinguishing characteristics and history, this article describes paper’s chemical composition, physical properties, preparation of the fibers, the use of chemical additives, formation, pressing, and drying of the sheet, coating and converting of paper, issues related to the environment and manufacturing efficiency, and a summary of common grades of paper and paperboard.