Production Experiences with the On-Line Vector Coater in Fine Paper Production, 2002 Coating Conference Proceedings

J. Ahlorrs, Å. Olsson, L. Westman, M. Nerpin and M. Plars

This paper discusses experiences of the first on-line installation of the Jagenberg Modular Combi Blade vector F-NIP 3 coater. The installation of two stations was carried out on PM10 at the Stora Enso Grycksbo Mill, in Sweden, in the summer of 1999. At the Grycksbo fine paper mill, coating is done on-line. The machine speed of PM10 is up to 1100 m/min and the basis weight varies from 70 to 115 g/m2, including a total coat weight range of 19-28 g/m2.

The main characteristic of the vector coater is a linear web guiding from the application through the blade nip. The coater has an 842mm-long dwell time between application and the blade, where color application and metering is achieved against two separate backing rolls. The web run is tangential through the blade nip. The long dwell time allows a relatively thick filter cake of coating color to build up on the sheet before the blade.

Different blade coating techniques such as jet and roll applications were evaluated in pilot trials to serve as a basis for the decision to re-build. The result of comparisons showed that the selected blade coater produced a lower surface roughness and gave the best coating coverage of the techniques evaluated, which resulted in less print mottle in black half tones and 100% cyan. In addition, a higher bending stiffness index and a higher print gloss were obtained. The coating results were interpreted to be in-between what is typical for "traditional blade coating" and "film coating."

Two years after the start-up, the break frequency and production efficiency of the machine are at the same level as before the rebuild. Before the rebuild the machine was running more than 200 m/min slower and had an on-line single station Billblade/HSM coater.