Paper and paperboard

This chapter will cover the applications of emulsion polymers in the paper industry. Today this industry consumes a volume of ca. 1.8 million metric tons of latex (dry) worldwide, mostly in surface sizing and paper coating. In western Europe about 3% of the paper industry s consumption of emulsion polymers go into surface sizing and 97% into paper coating. 

In 2000, the world production of paper and paperboard totalled 320 million metric tons and is expected to grow to about 420 million metric tons in 2010 with an annual growth rate of 2.7% (BASF AG). 

The main raw material used to make paper is wood. Depending on the quality demands for the final paper, wood typically will be processed into two modifications  

Especially in Europe recycled paper has become more and more important as a raw material for paper manufacturing. Modern technology combined with appropriate process chemicals enables this secondary raw material to be used not only for paperboard, but also for high-quality paper. In 2002, about 45% of the fibres used for paper-making in German paper mills came from recycled papers. For board-making the portion of recycled fibres was even 80%. Several paper mills are nowadays producing newsprint paper based on 100% recycled paper as fibre base. 

The largest part of the paper and board produced today is for printing purposes. The requirements that these materials must meet include  

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J. Farewell, ed.. Commercially Available Chemical Agents for Paper and Paperboard Manufacture, TAPPI Press, Adanta, Ga., 1990, pp. 17, 58—59. 

The AKDs are used in paper sizing appHcations. Paper sizing chemicals provide paper and paperboard with resistance to wetting by Hquids, especially water repeUency in paper cups, milk cartons, photographic paper, coatings, and packaging paper (139) (see Paper Papermaking additives). 

American Paper Institute 260 Madison Avenue New York, NY 10016 Physical standards, sizes, gauges, definitions of paper and paperboard. 

Wet Strength in Paper and Paperboard, TAPPl Monograph Series No. 29, Technical Association of the Pulp and Paper Industry, Adanta, Ga., 1965. 

J. C. W. Evans, ed.. Trends in Paper and Paperboard Converting, Lockwood Trade Journal Co., New York, 1965. 

Paper may be coated either on equipment that is an integral part of the paper machine, ie, on-machine coating, or on separate converting equipment. Many plants include both types of coating equipment and utilize each to its maximum advantage for paper and paperboard. The combination of techniques is of particular value where more than one coating must be appHed to the sheet in order to obtain a product of desired quaUty. 

R. H. Mark, Handbook of Physical and Mechanical Testing of Paper and Paperboard, Marcel Dekker, Inc., New York. 

In addition, many grades of paper and paperboard are used in direct or indirect contact with foods. Thus, many mills only use paper chemicals that have been cleared for use by the U.S. Pood and Dmg Administration (PDA) (3), so that it is not necessary to segregate machine broke (off-grade paper and edge clippings that are reclaimed for their fiber value) and white water. Most of the chemicals discussed in this article are approved by the PDA for use in paper and paperboard that are intended for appHcations in food processing and packaging. However, there are various restrictions on both the specific functional uses and amounts of paper chemical additives which can be used, so the PDA status should be confirmed by the suppHer before use. 

Fig. 2. Materials generated in the municipal waste stream from 1960 to 1995 (% of total generation), where (H) represents paper and paperboard, (H)...

The Hercules viscometer was originally designed for paper and paperboard coatings, but its use has been extended to paints, adhesives, mineral slurries, emulsions, and starch solutions. The iastmment, noted for being robust and rehable, is particularly well suited for quaUty control and product formulation. It is capable of measuting viscosity over a moderate range 1-10 mPa-s) up to high shear rates (115,000 ). A more recent model is the... 

Potassium sorbate, but not sorbic acid, is generally recognized as safe for use in animal feeds (154) and in paper and paperboard products for food packaging (155). 

R. A. Olson and P. T. Hoeldede, in R. Stiauss, ed.. Protein Binders in Paper and Paperboard Coating Tappi Monograph Series No. 36, Tappi Press, Adanta, Ga., 1975, pp. 75—96. 

Adhesives. Poly(vinyl alcohol) is used as a component in a wide variety of general-purpose adhesives to bond ceUulosic materials, such as paper and paperboard, wood textiles, some metal foils, and porous ceramic surfaces, to each other. It is also an effective binder for pigments and other finely divided powders. Both fully and partially hydrolyzed grades are used. Sensitivity to water increases with decreasing degree of hydrolysis and the addition of plasticizer. Poly(vinyl alcohol) in many appHcations is employed as an additive to other polymer systems to improve the cohesive strength, film flexibiUty, moisture resistance, and other properties. It is incorporated into a wide variety of adhesives through its use as a protective coUoid in emulsion p olymerization. 

The fully and super hydrolyzed PVA grades are preferred by the paper industry for their superior strength, greater adhesion to cellulose, better water resistance, and better foaming characteristics. However, the intermediate and partially hydrolyzed grades provide better surface filming characteristics on many paper and paperboard substrates. 

J. W. Swanson, ed.. Internal Sh ngof Paper and Paperboard, Monograph No. 33, Tappi Press, Atianta, Ga., 1971. 

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