Upm-kymmene Corporation

Jukka Kotilainen

Mikko Rissanen

Kaarina Kekäläinen

Harri Hiltunen

Jari Heikkinen

The invention relates to a method for manufacturing SCK paper having a basis weight in the range of 50 to 70 g/m, wherein an optimal combination of BSKP and BCTMP is used to adjust the properties of the fiber furnish. In SCK papers with low basis weight the bulk of the formed paper web upon paper manufacturing may be controlled by means of the fiber furnish, without downgauging and without adverse effects to other paper properties, which would prevent the use of the SCK paper as substrate layer in a release liner. Thus SCK paper with exceptionally high share of BCTMP in the fiber furnish may be produced into the same thickness as was possible before for a conventional supercalendered kraft paper having a higher basis weight, while maintaining other quality characteristics of the paper sufficient for use as a substrate layer of an industrial release liner.

BCTMP-tailored SCK paper for release liner

The invention relates to a supercalendered Kraft paper production for a release liner, which contains both non-recycled bleached chemical pulps and recycled pulp produced from release liner supercalendered Kraft paper. When highly specific raw material is used for recycling, the characteristics of the recycled pulp may be adjusted already upon recycling. The recycled pulp obtained from supercalendered Kraft paper that has been used as a substrate of a release liner may be used without further refining for manufacturing supercalendered Kraft paper. Excessive refining can thus be avoided and the compatibility of the recycled pulp may be optimized for supercalendered Kraft paper production. The non-recycled pulps may be refined less, as well. This leads to positive effects in supercalendered Kraft paper manufacturing process, such as improved dewatering and energy efficient drying. The produced paper demonstrates reduced shrinkage and improved dimensional stability, while maintaining sufficient quality for use as a substrate for a release liner. A supercalendered Kraft paper with improved sustainability is produced.

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Helsinki, Finland

Jukka Kotilainen