US 12,188,183 B2
Supercalendered kraft paper comprising recycled fiber
Jukka Kotilainen, Helsinki (FI); Mikko Rissanen, Helsinki (FI); and Petteri Lannes, Helsinki (FI)
Assigned to UPM-KYMMENE CORPORATION, Helsinki (FI)
Filed by UPM-KYMMENE CORPORATION, Helsinki (FI)
Filed on Dec. 30, 2022, as Appl. No. 18/091,505.
Prior Publication US 2024/0218598 A1, Jul. 4, 2024
Int. Cl. D21H 15/00 (2006.01); D21H 17/00 (2006.01); D21H 27/00 (2006.01); D21H 27/06 (2006.01)
CPC D21H 5/12 (2013.01) [D21H 3/00 (2013.01); D21H 5/0075 (2013.01); D21H 5/0077 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A supercalendered Kraft paper suitable for use as a substrate of a release liner, the supercalendered Kraft paper comprising fibers from
non-recycled bleached chemical pulp produced from hardwood,
non-recycled bleached chemical pulp produced from softwood, and
recycled pulp obtained from supercalendered Kraft paper that has been used as a substrate of a release liner,
the supercalendered Kraft paper having
a density equal to or higher than 1.030 g/cm3, when determined according to ISO 534,
a transparency equal to or higher than 36%, when determined according to ISO 2469,
a CIE whiteness, wherein
L* is in the range of 92 to 98,
a* is in the range of −4 to +2, and
b* is in the range of +5 to +11,
when determined according to ISO 11475:2017 (en), and
comprising the recycled pulp obtained from supercalendered Kraft paper that has been used as a substrate of a release liner in an amount equal to or higher than 5 wt. %, when determined as dry matter content according to SCAN-P 39:80.