A hollow cylindrical depth filter formed of fibers of a thermoplastic resin and having a thickness of a filter medium of 5 to 25 millimeters, in which the filter medium has a compression ratio of 0.2 or less when a load of 0.5 MPa is applied thereto, the filter medium has a fiber layer of at least three layers from a fluid inflow side toward an outflow side, porosity of the three layers are adjusted to a specific range, respectively, and intersection points of the fibers forming the filter medium are bonded, a mean interval between the intersection points is 2 to 100 times a mean fiber diameter of the fibers in a length direction, and a ratio of the mean fiber diameter on a surface on an upstream side to the mean fiber diameter on a surface on a downstream side of the filter medium is 0.9 to 1.2.

Provided is a fiber structure in which an extra-fine fiber layer and a substrate layer are integrated deeply. The fiber structure includes an extra-fine fiber layer 10 spreading in a plane direction, and a substrate layer 20 adjoining the extra-fine fiber layer, wherein the extra-fine fiber layer 10 includes extra-fine fibers having a number average single fiber diameter of 5 μm or less; the substrate layer 20 includes non-extra-fine fibers having a number average single fiber diameter of 7 μm or more; and in a cross section along a thickness direction of the fiber structure, the substrate layer 20 contains mixture portions 12 in each of which some of the extra-fine fibers pushed between the non-extra-fine fibers are widened in a crosswise direction.

A thermally bonded filtration media that can be used in high temperature conditions in the absence of any loss of fiber through thermal effects or mechanical impact on the fiber components is disclosed. The filter media can be manufactured and used in a filter unit or structure, can be placed in a stream of removable fluid, and can remove a particulate load from the mobile stream at an increased temperature range. The combination of bi-component fiber, other filter media fiber, and other filtration additives provides an improved filtration media having unique properties in high temperature, high performance applications.

A hemp-based nonwoven material manufactured by an air bonding process comprising a temperature of 150° C. for two minutes; said nonwoven material comprising between 1% and 99% hemp and between 1% and 99% of at least a second fiber; wherein the at least a second fiber is a synthetic fiber having a melt temperature of above 150° C.

A filtration medium for a filter, having high dust collection efficiency, low pressure loss, a long service life and sufficient processing strength into a filter. A combined fiber nonwoven fabric includes first fibers having a mean fiber diameter of less than 200 nanometers, and second fibers having a mean fiber diameter in the range of 200 to 5000 nanometers, in which basis weight of the combined fiber nonwoven fabric is in the range of 2.1 to 15.0 g/m.sup.2.

The present invention relates to a filter medium being at least formed of a pre-filter sub-strate laminated with a fine-filter substrate by means of a third binder, wherein the pre-filter substrate comprises synthetic fibers and a first binder, the pre-filter substrate work-ing as a combined surface and depth filter, and the fine-filter substrate comprises at least a second binder and one of synthetic fibers and inorganic fibers.

A system for thermally bonding nonwoven fibers of assemblages of nonwoven fibers loosely held together may include a processing duct including an inlet end, an outlet end, and an intermediate portion extending between the inlet end and the outlet end. The system also may include one or more heat inlets located in the intermediate portion and configured to facilitate introduction of heat and air flow into the intermediate portion. The system further may include an inlet air feed at the inlet end and configured to separate the assemblages upon entry into the inlet end and propel the assemblages into the intermediate portion. The system also may include one or more heating devices configured to heat the assemblages as the assemblages are conveyed toward the outlet end to form processed assemblages, each of the processed assemblages including at least some nonwoven fibers adhered to one another.

Stabilized air filters formed from mats of crosslinked protein-containing fibers are provided. The fibers are formed into a mat with pores that allow air to pass through while physically filtering particulate matter. The protein in the protein-containing fibers also serves to chemically filter polluted air passed through the filter. Specifically, chemical functional groups from the many amino acids that comprise the protein of the protein-containing nanowire react with certain chemical pollutants (e.g., carbon monoxide and formaldehyde) in order to capture or otherwise neutralize the pollutant. Accordingly, the single fiber mat performs two filtering functions. Methods for making the air filters from crosslinked protein-containing nanofibers are also provided.

A method for manufacturing a filtration media with improved filtration, strength, tear resistance and air permeability in the form of a relatively thin and lightweight wet-laid fibrous web that has a wet Mullen ratio of 20% to 90% to ensure that the media is flexible enough to be formed into a fluted structure, and strong enough to retain the fluted structure when would into a roll and to permit further processing.

Disclosed are improved polymer materials. Also disclosed are fine fiber materials that can be made from the improved polymeric materials in the form of microfiber and nanofiber structures. The microfiber and nanofiber structures can be used in a variety of useful applications including the formation of filter materials.