METHOD FOR OBTAINING MULTILAYER PAPER Russian patent published in 2023 - IPC D21H23/50 D21F11/04 D21H17/34 D21H17/37 D21H21/20 D21H27/30 

FIELD: paper industry.

SUBSTANCE: group of inventions can be used in the manufacture of multilayer packaging paper or cardboard. The process for producing dried multilayer paper includes producing first and second fibrous webs by dehydrating an aqueous fibrous suspension and spraying at least one side of the first and/or second fibrous web with a spray solution or spray suspension. The first and second fibrous webs are joined and then the resulting laminate is partially dehydrated by pressing. The partially dehydrated laminate is dried with heat to form a multilayer paper. Spray solution or spray suspension contains at least 75 wt% of water and water-soluble polymer P. Water-soluble polymer P is obtained by polymerization of the monomer of formula I,

where R ¹ means H or C1-C6 alkyl, and one or more ethylenically unsaturated monomers that are different from the monomer of formula I. A paper machine is also proposed.

EFFECT: group of inventions makes it possible to increase the strength of internal adhesion of layers in multilayer paper.

10 cl, 6 tbl