The filter for gel shearing and particle filtration of molten polymer has a first layer of metal fibers of an average equivalent diameter between 8 and 65 m. The cross-section of the metal fibers has two neighboring straight sides with an included angle of less than 90 and one or more irregularly shaped curved sides. The metal fibers have an average length of at least 6 mm. The metal fibers are bonded to each other by metal bonds; where the metal of the metal fibers of the first layer is the bonding agent forming the metal bonds. The filter has a second layer of metal fibers. The average equivalent diameter of the metal fibers of the second layer is smaller than the average equivalent diameter of the metal fibers of the first layer.

The invention relates to a method for producing a filter device (1) for filtering a hydrophilic liquid, comprising a flat filter element (10) which is permeable to the liquid, wherein the filter element (10) has a delimited filter region (11) which is coated with a hydrophobic agent. The following steps are carried out: a) providing the flat filter element (10) which has in particular a nonwoven filter web (13) lying between a mesh support layer (14) and a spun-bonded fabric (15), b) producing a compressed annular boundary region (16) for the filter region (11), c) applying the agent onto the filter region (11) of the filter element (10), and d) obtaining the filter device (1).

Filter media and filters are provided having a fibrous web including first and second dissimilar electret fibers ultrasonically bonded to each other. The first and second electret fibers may be directly bonded to each other without needle punching, which substantially maintains the thickness or loft of the fibrous web of the filter media and filters. Maintaining the thickness or loft of the fibrous web during the bonding process decreases the pressure drop across the filter media and increases its dust holding capacity. Medical grade filters and/or self-supporting (i.e., self-pleatable) air filters are also provided. The medical grade filters and/or self-supporting air filters may include one or more support layers ultrasonically bonded to the fibrous web or fiber layers without needle punching, which maintains the stiffness of the support layers and allows the filter to be produced in a single manufacturing step.

A self-support electrostatic filter has a filter media made of charged filter media with a first surface and a second surface, and two non-woven scrim layers made of welded long fibers. The non-woven scrim layers are ultrasonically bounded with the surfaces of the self-support electrostatic filter to form a triple layered filter media with supporting surfaces. Thus the triple layered filter media can be wavy folded for self-support without adhering to a piece of expanded metal mesh.

One aspect of the technology relates to a recirculation filter. The recirculation filter has a first outer layer defining at least a portion of a first flow face of the recirculation filter, where the first flow face is configured to be positioned adjacent to a sensitive component in an electronics enclosure. A second outer layer defines at least a portion of a second flow face of the recirculation filter. A filter material layer is disposed between the first outer layer and the second outer layer. The filter material layer has a central region, wherein a substantial portion of the central region is offset from the first flow face of the recirculation filter. Other aspects are also described.

The present invention provides a nonwoven fabric sheet for use in extraction filters having high sealing strength and extraction filters manufactured using the nonwoven fabric sheet. The nonwoven fabric sheet includes a first layer including a spunbonded nonwoven fabric formed from a polyester-based resin having an IV value of 0.60 to 1.00, a crystallinity of 30% to 80%, a crystalline orientation of 60% to 95%, and a birefringence (n) of 0.040 to 0.100 and provided with a partial thermocompression bonding section whose thermocompression bonding area rate is in the range of 5% to 30%, and a second layer including a meltblown nonwoven fabric formed from a polyester-based resin blown onto a surface of the first layer and solidified to have a crystallinity of 0% to 14%. The extraction filters are formed by sealing by welding the nonwoven fabric sheet with the second layer of the sheet placed inside.

A filtration barrier comprises at least one barrier layer which includes polymeric nanofibers interlaced with microfibers, and at least one substrate layer which includes polymeric microfibers. The filtration barrier can be made by electrospinning process.

A filtration barrier comprises at least one barrier layer which includes polymeric nanofibers interlaced with microfibers, and at least one substrate layer which includes polymeric microfibers. The filtration barrier can be made by electrospinning process.

The present disclosure provides composite materials comprising reticular structures, such as nettings, mattings, grids, meshes or the like, ultrasonically bonded to outer layers of non-woven fibers. A composite material comprises a first layer of netting comprising strands and a second layer of nonwoven fibers in contact with the first layer. The nonwoven fibers are ultrasonically bonded to the strands of the netting at a plurality of attachment points. The basis weight of the netting and/or the fibers in the second layer are selected to optimize the bonding and increase the overall strength of the material. In embodiments wherein the composite material is used as a filter media, the filter has a longer lifespan, without compromising other performance factors, such as efficiency and capacity.

Filter media, filters and methods for preparing filter media are provided herein. The filter media may include a nonwoven sheet having continuous fibers prepared from first and second dissimilar polymers that are triboelectrically charged. The nonwoven sheet may be prepared by needling and/or hydroentangling the continuous fibers. Needling and/or hydroentangling the continuous fibers triboelectrically charges at least a portion of the continuous fibers of the nonwoven sheet. In addition, needling and/or hydroentangling the fibers increases the loftiness of the nonwoven sheet, thereby reducing its resistance to airflow and increasing its dust holding capacity.