The invention relates to a method for forming a three-layer board web, preferably a folding box board (FBB) or a solid bleached (sulfate) board (SBS), in a forming section (300) comprising a multilayer headbox (100) and a forming unit (200). In the method the layers of the three-layer board web are first formed of pulp suspension in the multilayer headbox (100) and fed to only one forming unit (200), a gap former where the pulp suspension from the multilayer headbox is fed to a gap between lower and upper wires for water removal and for joining the layers of the three-layer board web and where water is first removed by a non-pulsating forming shoe (37, 39).

Multi-ply paper products and methods for manufacturing such products are provided. A method includes producing a foam of water, air, a foaming agent, uncooked starch, and a dry strength agent; applying the foam to a first surface of a base embryonic ply web; providing an applied embryonic ply web having a first surface and contacting the first surface of the base web with the first surface of the applied web at an interface to form a combined ply web; and selectively applying vacuum pressure to a second surface of the base web to retain particles of the uncooked starch on or near the first surface, to draw molecules of the dry strength agent into the base web and/or to the first surface of the applied web to retain particles of the uncooked starch in the interface and to draw molecules of the dry strength agent into the applied web.

The present invention relates to a method for manufacturing a multilayer film comprising highly refined cellulose fibers, the method comprising the steps of: a) forming a first wet web by applying a first pulp suspension comprising highly refined cellulose fibers on a first wire; b) partially dewatering the first wet web to obtain a first partially dewatered web; c) forming a second wet web y applying a foamed second pulp suspension comprising highly refined cellulose fibers and a foaming agent on a second wire; d) partially dewatering the foamed second wet web to obtain a second partially dewatered web; e) joining the first and second partially dewatered web to obtain a multilayer web; and f) further dewatering, and optionally drying, the multilayer web to obtain a multilayer film comprising highly refined cellulose fibers.

A method for producing a paperboard comprising the steps of; providing a furnish comprising cellulosic fibers, applying the furnish on at least one wire to form a web, dewatering the web on said at least one wire by subjecting the web to a pressure above 150 kPa without the use of a press roll nip and thereafter pressing the dewatered web to form a paperboard. Also a paperboard and a corrugated board produced by such a process.

A process for making a paper product comprising: providing a forming fabric; causing the forming fabric to rotate such that an upper surface of the forming fabric moves in a machine direction; providing a multi-layer headbox comprising first and second inlet headers and a slice outlet; providing a first aqueous slurry of first fibers to the first inlet header and a second aqueous slurry of second fibers to the second inlet header; combining streams of the first and second aqueous slurries to define a jet exiting the slice outlet; emitting the jet onto the upper surface of the forming fabric to form a web; causing the forming fabric to oscillate in a direction transverse to the machine direction, whereby at least a significant number of the first fibers are caused to align in a direction that deviates from the machine direction; and forming the paper product from the web.

A method of forming a fibrous web including the steps of providing a fiber slurry, depositing the fiber slurry between an inner forming wire and an outer forming wire, wherein the outer forming wire comprises a structured fabric and the inner forming wire contacts a segment of a forming roll, and rotating the forming roll so that the fiber slurry moves into contact with the structured fabric.

A method is disclosed for increasing strength properties, preferably burst strength and SCT strength, of a paper or board product. The paper or board product is manufactured from a fibrous web produced by a multilayer headbox, where an aqueous layer is formed between at least a first and a second fibre layer formed from fibrous stock suspension(s), and where feed water for the aqueous layer includes at least one cationic polymer. The method of the invention includes adding an anionic additive selected from a group comprising anionic synthetic organic polymers, anionic polysaccharides, and any of their combinations to the feed water before formation of the aqueous layer.

A process for making a paper product comprising: providing a forming fabric; causing the forming fabric to rotate such that an upper surface of the forming fabric moves in a machine direction; providing a multi-layer headbox comprising first and second inlet headers and a slice outlet; providing a first aqueous slurry of first fibers to the first inlet header and a second aqueous slurry of second fibers to the second inlet header; combining streams of the first and second aqueous slurries to define a jet exiting the slice outlet; emitting the jet onto the upper surface of the forming fabric to form a web; causing the forming fabric to oscillate in a direction transverse to the machine direction, whereby at least a significant number of the first fibers are caused to align in a direction that deviates from the machine direction; and forming the paper product from the web.

The present invention relates to a method for producing a paperboard comprising the steps of; providing a furnish comprising cellulosic fibers, applying the furnish on at least one wire to form a web, dewatering the web on said at least one wire by subjecting the web to a pressure above 150 kPa without the use of a press roll nip and thereafter pressing the dewatered web to form a paperboard. The invention also relates to a paperboard and a corrugated board.

A method for forming a multi-ply fiber web in which least part of the sizing of the multi-ply fiber web is provided by applying sizing agent in the form of foam by a curtain type application device (C10, C20) in between at least two layers of the multi-ply fiber web in the forming section. The invention also relates to a forming section for a multi-ply fiber web having at least one twin-wire forming part formed between a wire (10) for the bottom layer and a wire (20) for the top layer of the multi-ply fiber web, where the layers are joined, and the treated layers combined. The forming section has a curtain type application device (C10, C20) for applying sizing agent in the form of foam in between two layers of the multi-ply fiber web in the forming section of a multi-ply fiber web production line.