Ahlstrom Glassfibre Oy

Ahlstrom Paper Group Oy

Weyerhaeuser Company Limited

Ahlstrom Paper Group Research & Competence Center

Kay Rokman

Juhani Jansson

Eino Laine

Jorma Elonen

Arto Koso

Hakan Sabel

Kelly Rennels

Rod Komlenic

Peter A Graef

Fred B Howard

Charles E Miller

Daniel T Bunker

Shahrokh A Naieni

David G Marsh

Jeffrey D Mathews

Terry M Grant

Jonathan George

Harri Kostamo

Andrea Grosso

Raimo Piittala

Rainer Blomqvist

Kaj Back

Melissa L Dopps

Raine Suurnakki

The present invention relates to a method and apparatus for foam forming, wherein fibrous foam suspension is introduced from the head box () of a production machine to the web forming section thereof. At least one solid material is mixed into the foam in the head box (). The method and the apparatus of the invention are particularly suitable for manufacturing various web-like products of cellulose, glass fiber, aramide, sisal, or other corresponding fibre material.

Method and apparatus for foam forming

A unitary absorbent composite having a plurality of strata is disclosed. In the composite, adjacent strata are separated by a transition zone integrally connecting the strata. Each stratum includes fibers and a binder, and the transition zone includes fibers from adjacent strata. Method for forming the unitary composite are also disclosed.

Unitary absorbent system

A non-woven web of fibrous material is produced using a moving foraminous element in the practice of the foam process. A first foam slurry of air, water, fibers and a surfactant is generated and centrifugally pumped into contact with the moving foraminous element. Substantially fiber-free foam is withdrawn from the foraminous element while forming a non-woven web of fibrous material on the foraminous element, and at least a part of the substantially fiber-free foam is used in the generation of the first foam slurry. Recycling is also typically practiced using a centrifugal pump, and the centrifugal pumps are preferably degassing pumps which remove some of the gas from the foam. By practicing the invention it is possible to produce fibrous webs using the foam process that are more than two meters wide, and at a forming speed of more than about 100 m/min (e.g. about 200-500 m/min).

Using centrifugal pumps in the foam process of producing non-woven webs

A non-woven web of cellulosic synthetic fibrous material is produced using a twin wire former. The former may have a closed first end and closed first and second sides, and a second end provided by first and second moving foraminous elements. An interior structure between the sides and second end may have at least first and second different length pluralities of conduits extending from the former first end toward the second end, and defining by themselves, or with wall elements, the interior volume into a first volume and a second volume on opposite sides thereof. A first fiber/foam slurry is introduced into the first volume and a second fiber/foam slurry in the second volume, and suction box assemblies are provided on the opposite sides of the foraminous elements from the interior volume for withdrawing foam from the slurries to forming a non-woven web on the foraminous elements. At least a third material is introduced using the interior structure so that the third material does not come into direct contact with either foraminous element, and the third material may form stripes in the web. The positions of the at least third material third conduits may be adjusted one or both of vertically and horizontally.

Twin wire former assembly

A non-woven web of fibrous material containing a reactive particulate material is made using the wet laid, or preferably foam, process. First and second fibrous webs are made using the wet laid or foam process, and a liquid or foam slurry including reactive particulate material is provided between the webs so as to provide a composite web. Liquid, or foam and liquid, are withdrawn from the composite web and then the composite web is dried so as to produce a final non-woven web with reactive material having substantially optimum reactivity (that is the reactive material loses a minimum amount reactivity during the web production process). The webs and slurry may be made using substantially pure water, and the particulate part of the reactive material is mixed with the foam or liquid slurry no more than about ten seconds before the liquid and/or foam are withdrawn from the composite web. Activated carbon and titanium dioxide are two particularly desirable reactive particulates; the reactive loading is at least 0.01 g/cm , and the air permeability of the final web is at least 3000 liters per square meter per second.

Production of reactive material containing webs

A printed circuit board is made from at least one non-woven sheet or web layer comprising at least 50% by weight acrylic fibers, with any balance substantially electrically non-conductive fibers, filler, and binder. The sheet or web is preferably made by the foam process, and may contain 60-80% straight polyacrylonitrile fibers and 40-20% fibrillated (pulp) ones. The web or sheet is preferably compressed by thermal calendering so that it has a density of about 0.1-1 grams per cubic centimeter; and the web or sheet may have a basis weight of between about 20-120 grams per square meter. The web or sheet may also have a 1-40% of substantially electrically non-conductive organic or inorganic binder, or may be substantially binder free. A printed circuit board made using the layers of these non-woven webs or sheets is otherwise conventional, including a pre-preg material, electrically conductive circuit elements, and electronics, and has improved properties compared to woven glass and non-woven aramid products, including improved fiber consolidation, easy board construction, and improved MD/CD ratio and stability.

Base webs for printed circuit board production using the foam process and acrylic fibers

Foam process for producing multi-layered webs

A displacement pump for a relatively high pressure performance environment includes a casing with first and second ends, with rotors driven in the casing to effect pumping. Flushing fluid (such as sealing water or substantially fiber-free foam) is introduced into a clearance between the rotors and the interior surface of the second end of the casing to keep the clearance substantially free of undesirable particles or fibers, typically fibers (such as glass fibers) having greater abrasiveness than cellulose fibers, or fibers (such as synthetic fibers, or synthetic material coating cellulose fibers) having poorer heat resistance than cellulose fibers. The flushing fluid may be introduced into the clearance in a number of different ways as long the clearance is kept substantially free of the undesirable particles or fibers. The flushing fluid is introduced, preferably through a check valve, at a pressure at least slightly higher than the output pressure of the pump.

Displacement pump and method of use thereof

In an assembly and method for producing a non-woven web of fibrous material utilizing the foam process, an edge seal for the former is provided which can include the introduction of substantially free foam into the edge seal for providing lubrication and to prevent leakage of fiber-containing slurry from the former. Web formation is primarily due to a mechanical force provided by nip rolls, although suction tables and other suction devices are also provided to carry away foam removed by the nip rolls, or at other stages. The foam/fiber slurry may be formed by introducing the foam tangentially into a tank at a plurality of locations to establish a vortex, and by introducing fiber into the top of the tank, and pumping from the bottom of the tank. The foam/fiber slurry may be introduced using a structure that can be reciprocated toward and away from the inlet of the former, and which has a number of changes defined by pivoted or flexible plates to form distinct strata at least at the start of web formation.

Foam process web formation using pressure removal of fluid

The foam process is used to make non-woven webs from cellulose or synthetic fibers, which webs have as a component super absorbent polymer (SAP). In order to minimize water absorbency by the SAP, it may have a protective coating that dissolves only after in contact with water a few seconds; the SAP may be frozen (e.g. to about -18.degree. C.); and/or the SAP may be transported by highly chilled (e.g. about 1.degree. C.) water. The SAP, and liquid or foam carrier, is fed as a small volume flow into a conduit carrying a high volume flow of a fiber containing foam slurry, just before a foraminous element. A mechanical mixer may be provided in the conduit for mixing the SAP with the fiber-foam slurry. The addition of the SAP to the carrier fluid takes place no more than ten seconds (preferably no more than five seconds) before the fiber-foam slurry mixed with SAP is brought into operative association with one or more foraminous elements. The SAP in the formed web, before drying, has a dry content of at least 20% (typically between about 30-40+%).

Effective utilization of sap in producing non-woven webs using the foam

In a foam laid process for producing a non-woven web of fibrous material (such as of synthetic or cellulose fibers) substantially fiber free foam is introduced at various locations in or adjacent to a headbox to get improved results. By introducing pure foam into the foam-fiber mixture near (e.g. just before) where the foam-fiber mixture is introduced into the headbox a more uniform basis weight profile of the non-woven web produced may be provided (e.g. a basis weight variation of about 0.5% or less). By introducing another stream of substantially fiber free foam into the headbox at a surface remote from the foraminous element, to flow along the surface (typically parallel to the flow of the foam fiber mixture), it is possible to minimize shear of fibers in the headbox so that the fibers do not become unidirectional, in the direction of movement of the foraminous element, and keep the surface clean. The surface is typically a roof surface of an inclined headbox.

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Karhula, Finland

Kay Rokman