Paper coating

Paper is coated in order to provide it with an additional property or functionality, such as gloss, sealability, or a barrier against mineral oil. Without a paper coating, specialty paper such as thermal paper, carbonless paper, fine paper, and flexible packaging paper simply wouldn’t exist. But what exactly is a paper coating? Easy: A solution or dispersion, usually aqueous, that is evenly applied on the surface of paper after the latter is made. Once this solution or dispersion dries, a continuous coating is produced.

Within this context, a distinction is drawn between pre-coatings and functional coatings: A pre-coating covers the rough, open paper surface and smooths it additionally, usually preparing the base paper surface for the application of a functional coating as a result. This prevents the functional coating from penetrating the open paper structure. One clear advantage of this: Less functional coating is required. The coatings can be applied with a variety of equipment and methods, including a film press, a blade, or curtain coating.

The challenge when it comes to a good paper coating is to get a dispersion and an application method that work optimally with each other. In short: It must be possible to evenly apply the dispersion formulation, and they must dry evenly as well. Coating machine 8 at the Koehler Paper site in Kehl can produce an enormous range of specialty papers. In fact, the state-of-the-art machine makes it possible to apply up to three coatings in a single process. For example, a pre-coating and functional coating can be applied in a single pass, or two functional coatings can be applied simultaneously with curtain coating.

Koehler Paper’s expertise when it comes to producing specialty paper such as thermal paper, carbonless paper, fine paper, and flexible packaging paper is based on decades of experience developing dispersions. From initial laboratory and test coating machine tests to the production coating system, our experts from Technology, Process Technology, and Production tend to every step related to our developments.