US 12,473,693 B2
BCTMP-tailored SCK paper for release liner
Mikko Rissanen, Helsinki (FI); Jukka Kotilainen, Helsinki (FI); Harri Hiltunen, Helsinki (FI); Kaarina Kekäläinen, Helsinki (FI); and Jari Heikkinen, Helsinki (FI)
Assigned to UPM-KYMMENE CORPORATION, Helsinki (FI)
Filed by UPM-Kymmene Corporation, Helsinki (FI)
Filed on Feb. 24, 2023, as Appl. No. 18/113,743.
Prior Publication US 2024/0287741 A1, Aug. 29, 2024
Int. Cl. D21H 27/00 (2006.01); D21H 11/02 (2006.01); D21H 11/04 (2006.01); D21H 11/20 (2006.01)
CPC D21H 27/001 (2013.01) [D21H 11/02 (2013.01); D21H 11/04 (2013.01); D21H 11/20 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A supercalendered kraft paper suitable for use as a substrate layer of an industrial release liner for adhesive labels, the supercalendered kraft paper comprising
a basis weight in the range of 50 to 70 g/m2, when determined according to ISO 536, and
a fiber furnish determinable with standard ISO 9184-4 in conjunction with standard ISO 9184-1, the fiber furnish comprising
bleached hardwood kraft pulp,
bleached softwood kraft pulp and
bleached chemithermomechanical pulp,
wherein the fiber furnish has an average length weighted fiber length in the range of 0.90 to 1.14 mm, when determined according to ISO 16065-2:2014,
such that the supercalendered kraft paper contains
the bleached chemithermomechanical pulp in an amount equal to or higher than 5 wt. % and the bleached softwood kraft pulp in an amount equal to or higher than 15 wt. %, when determined as dry matter content of the paper according to SCAN-P 39:80,
the supercalendered kraft paper thereby having
a tear index in the cross direction of the paper higher than 5 mNm2/g, when determined according to ISO 1974,
a transparency level equal to or higher than 40%, when determined according to ISO 2469 and
a density in the range of 1040 to 1140 kg/m3, when determined according to ISO 534.
 
15. A method of manufacturing supercalendered kraft paper suitable for use as a substrate layer of an industrial release liner for adhesive labels, the method comprising
mixing together
bleached hardwood kraft pulp,
bleached softwood kraft pulp, and
bleached chemithermomechanical pulp,
wherein the fiber furnish has an average length weighted fiber length in the range of 0.90 to 1.14 mm, when determined according to ISO 16065-2:2014,
such that a pulp mixture is obtained, which has a fiber furnish determinable with standard ISO 9184-4 in conjunction with the standard ISO 9184-1,
forming a paper web from the pulp mixture on a paper machine,
reducing moisture content of the paper web in a press section,
drying the paper web in a drying section, thereby forming paper, and
calendering the paper,
such that a supercalendered kraft paper is obtained having a basis weight in the range of 50 to 70 g/m2, and which contains the bleached chemithermomechanical pulp in an amount equal to or higher than 5 wt. % and the bleached softwood kraft pulp in an amount equal to or higher than 15 wt. %, when determined as dry matter content of the paper according to SCAN P 39:80,
the supercalendered kraft paper thereby having
a tear index in the cross direction of the paper higher than 5 mNm2/g, when determined according to ISO 1974,
a transparency level equal to or higher than 40%, when determined according to ISO 2469 and
a density in the range of 1040 to 1140 kg/m3, when determined according to ISO 534.