Ahlstrom Glassfibre Oy

Ahlstrom Paper Group Oy

Weyerhaeuser Company Limited

Juhani Jansson

Kay Rokman

Eino Laine

Jorma Elonen

Arto Koso

Kay R&ouml;kman

Peter A Graef

Fred B Howard

Charles E Miller

Daniel T Bunker

Shahrokh A Naieni

David G Marsh

Jeffrey D Mathews

Terry M Grant

Harri Kostamo

Melissa L Dopps

Juha Bohm

A non-woven mat useful for a wide variety of purposes, including forming reinforced resin products, is produced in a manner having different specific uses of, and advantages over, conventional chopped strand mats and conventional glass tissue. The mat is preferably made by the foam process (but may be made by the liquid process), and at speeds well in excess of 60 m./min., and has a substantially uniform construction even when low density (e.g. 100 g/m or less). At least 20% (preferably at least 85%) of the fibers are in fiber bundles with between 5-450 fibers/bundle. The fibers (typically at least 85%) have a length between 5-100 mm, preferably 7-50 mm, substantially the same as the length of the fiber bundle they are in. The fibers are preferably held in the bundles by substantially non-water soluble sizing, such as epoxy resin or PVOH. The fibers in the bundles typically have diameters of approximately 7-500 microns, preferably about 7-35 microns. The bundles may comprise at least 10% reinforcing fibers, such as glass, aramid or acrylic.

Chopped strand non-woven mat production

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 Substantially fiber-free foam is withdrawn from the foraminous element while forming a non-woven web of fibrous material on the foraminous element, and at least a part of the substantially fiber-free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 nonwoven web of fibrous material is made by the foam process using a manifold of a particular construction. The manifold has a casing with first and second opposite ends including an inlet for a foam-fiber-surfactant slurry at the first end, and optionally a valved outlet at the second end. A center section of the manifold casing has a (e.g. rectangular) cross-section that becomes smaller moving from an inlet toward the outlet. First and second substantially closed side walls, a porous front wall having an effective length, and a back wall opposite the front wall, are provided for the center section, the walls planar or curved. Any suitable structures are provided for introducing a second (e.g. substantially fiber-free, or a fiber-foam slurry) foam into the center section through the back wall. Pressure sensors penetrating one or both of the side walls may sense the pressure within the center section, and automatically control the introduction of slurry into the inlet, withdrawal through the outlet, and/or introduction of the second foam into/through the back wall, so as to maintain the basis weight of the foam-fiber slurry passing through the front wall substantially constant along the effective length of the front wall.

Foam process web production with foam dilution

Foam process for producing multi-layered webs

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.

Growing community of inventors

Karhula, Finland

Juhani Jansson