US 11,807,986 B2
Process and apparatus for wetlaying nonwovens
Arie Venema, Suameer (NL); Gaatze Wijbenga, Noardburgum (NL); Hannu Ahoniemi, Gothenburg (SE); and Mikael Strandqvist, Gothenburg (SE)
Assigned to ESSITY HYGIENE AND HEALTH AKTIEBOLAG, Gothenburg (SE)
Filed by Essity Hygiene and Health Aktiebolag, Gothenburg (SE)
Filed on Apr. 21, 2021, as Appl. No. 17/236,483.
Application 17/236,483 is a continuation of application No. 16/326,823, granted, now 11,015,292, previously published as PCT/EP2016/070626, filed on Sep. 1, 2016.
Prior Publication US 2021/0238804 A1, Aug. 5, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. D21F 11/00 (2006.01); D21F 1/66 (2006.01); D04H 1/732 (2012.01); D21H 21/24 (2006.01); D04H 1/00 (2006.01); D21H 15/02 (2006.01)
CPC D21F 11/002 (2013.01) [D04H 1/00 (2013.01); D04H 1/732 (2013.01); D21F 1/66 (2013.01); D21H 15/02 (2013.01); D21H 21/24 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A process of producing a nonwoven sheet material of natural and/or man-made fibres, comprising:
a) providing a three-phase (gas-liquid-solid) suspension containing:
water, natural fibers, man-made fibres, or both natural fibers and man-made fibers,
a surfactant, and
20-50 volume % of air,
b) depositing the suspension onto a moving carrier sieve to produce a fibrous web on the carrier sieve,
c) removing aqueous residue of the suspension through the carrier sieve, and
e) recycling the aqueous residue to step a),
wherein the aqueous residue, before step e), is subjected to a step d) of phase separation, in which the aqueous residue is conveyed through one or more phase separation tanks in an essentially horizontal direction while providing a depressurised headspace above the aqueous residue, the phase-separation resulting in reducing an air content of the aqueous residue to below 20 volume %.