US 12,110,636 B2
Filter paper
Dieter Möhring, Wattens (AT); and Guido Reiter, Terfens (AT)
Assigned to DELFORTGROUP AG, Traun (AT)
Appl. No. 17/043,486
Filed by DELFORTGROUP AG, Traun (AT)
PCT Filed Mar. 4, 2019, PCT No. PCT/EP2019/055290
§ 371(c)(1), (2) Date Sep. 29, 2020,
PCT Pub. No. WO2019/192787, PCT Pub. Date Oct. 10, 2019.
Claims priority of application No. 10 2018 107 944.3 (DE), filed on Apr. 4, 2018.
Prior Publication US 2021/0123189 A1, Apr. 29, 2021
Int. Cl. D21H 27/08 (2006.01); D21H 13/24 (2006.01); D21H 13/26 (2006.01); D21H 17/67 (2006.01)
CPC D21H 27/08 (2013.01) [D21H 17/675 (2013.01); D21H 13/24 (2013.01); D21H 13/26 (2013.01)] 37 Claims
 
1. A filter paper for the production of an aqueous extract, comprising softwood pulp, which has the following properties:
a basis weight of more than 9.0 g/m2 and less than 13.5 g/m2,
a density of more than 280 kg/m3 and less than 350 kg/m3,
a roughness of more than 700 ml/min and less than 1300 ml/min,
a bending resistance in the machine direction of more than 50 mN and less than 75 mN, and
an air permeability of more than 17000 cm/(min·kPa) and less than 26000 cm/(min·kPa),
wherein the filter paper is either free from abacá fibers and sisal fibers or, if abacá fibers and/or sisal fibers are present, taken together they make up less than 20% of the paper mass, and
wherein the content of softwood pulp in the filter paper is at least 70% with respect to the mass of the filter paper.