# US 5,702,616 A · Aramid fiber filtration sheet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,702,616 A - Document ID: US5702616A - Status: Granted - Kind: A - Application number: 08/638,958 - Filed: 1996-04-24 - Granted: 1997-12-30 - Earliest claimed: 1994-04-29 - Assignees: Pall Corporation - Inventors: Peter J. Degen; Warren M. Foss - Web page: https://patentgrep.com/patent/US5702616A ## CPC - B01D 39/083: {of organic material} - D04H 1/42: characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece - D21H 27/08: Filter paper (self-supporting filtering material B01D39/14; making on paper-making machines D21F11/14) - B01D 2239/065: More than one layer present in the filtering material - B01D 2239/0654: Support layers - B01D 2239/1291: Other parameters - D21H 13/26: Polyamides; Polyimides - Y10T 428/268: Monolayer with structurally defined element - Y10T 428/29: Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof - Y10T 428/2969: Polyamide, polyimide or polyester - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - D04H: MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL (weaving D03; knitting D04B; braiding D04C; net-making D04G; sewing D05B; tufting D05C; finishing non-woven fabrics D06); FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING {; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION}(non-woven fabrics having an intermediate or external layer of a different kind, e.g. of woven fabric, B32B) - D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The present invention provides a polymeric, particularly aramid, fiber filtration sheet having a relatively small pore size and high pore uniformity. The present inventive aramid fiber filtration sheet preferably has a titer reduction against bacteria such as Pseudomonas diminuta. The present invention also provides a method of preparing reduced-diameter aramid fibers, as well as a method of preparing an aramid fiber filtration sheet from such reduced-diameter aramid fibers. The present invention further provides a method of treating a fluid by passing a fluid through the present inventive aramid fiber filtration sheet, as well as a filter element incorporating the present inventive aramid fiber filtration sheet. ## Claims ### Claim 1 A method of treating a fluid comprising passing a fluid through an aramid fiber sheet having a first bubble point of about 100 in. water column or more. ### Claim 2 (depends on 1) The method of claim 1, wherein said fluid comprises bacteria in excess of 10.sup.2 /ml before being passed through said aramid fiber sheet and less than 10.sup.2 /ml after being passed through said aramid fiber sheet. ### Claim 3 (depends on 2) The method of claim 2, wherein said fluid comprises bacteria in excess of 10.sup.4 /ml before being passed through said aramid fiber sheet. ### Claim 4 (depends on 3) The method of claim 3, wherein said fluid comprises no bacteria after being passed through said aramid fiber sheet. ### Claim 5 A method of treating a fluid comprising passing a fluid through an aramid fiber sheet having a titer reduction of about 10.sup.5 or more against Pseudomonas diminuta. ### Claim 6 (depends on 5) The method of claim 5, wherein said fluid comprises bacteria in excess of 10.sup.2 /ml before being passed through said aramid fiber sheet and less than 10.sup.2 /ml after being passed through said aramid fiber sheet. ### Claim 7 (depends on 6) The method of claim 6, wherein said fluid comprises bacteria in excess of 10.sup.4 /ml before being passed through said aramid fiber sheet. ### Claim 8 (depends on 7) The method of claim 7, wherein said fluid comprises no bacteria after being passed through said aramid fiber sheet. ### Claim 9 A filter element comprising an aramid fiber sheet having a first bubble point of about 100 in. water column or more and sides which have been overlapped and sealed to form a tubular configuration having an exterior surface, an interior, and two ends, and end caps sealed to the ends of the tube, wherein at least one of said end caps has a central aperture providing access to the interior of the tube, and all of said seals are fluid-tight. ### Claim 10 (depends on 9) The filter element of claim 9, wherein said aramid fiber sheet is corrugated. ### Claim 11 (depends on 9) The filter element of claim 9, wherein at least one of the sides of said aramid fiber sheet is mated to a porous support layer. ### Claim 12 (depends on 11) The filter element of claim 11, wherein said aramid fiber sheet and said porous support layer are corrugated. ### Claim 13 (depends on 12) The filter element of claim 12, wherein said filter element comprises multiple aramid fiber sheets mated together. ### Claim 14 A filter element comprising an aramid fiber sheet having a titer reduction of about 10.sup.5 or more against Pseudomonas diminuta and sides which have been overlapped and sealed to form a tubular configuration having an exterior surface, an interior, and two ends, and end caps sealed to the ends of the tube, wherein at least one of said end caps has a central aperture providing access to the interior of the tube, and all of said seals are fluid-tight. ### Claim 15 (depends on 14) The filter element of claim 14, wherein said aramid fiber sheet is corrugated. ### Claim 16 (depends on 14) The filter element of claim 14, wherein at least one of the sides of said aramid fiber sheet is mated to a porous support layer. ### Claim 17 (depends on 16) The filter element of claim 16, wherein said aramid fiber sheet and said porous support layer are corrugated. ### Claim 18 (depends on 17) The filter element of claim 17, wherein said filter element comprises multiple aramid fiber sheets mated together. ### Claim 19 A filter element comprising an aramid fiber sheet having a first bubble point of about 100 in. water column or more helically wrapped around a pervious, hollow tube to form an overlap of 0% to about 95% of the width of said aramid fiber sheet. ### Claim 20 (depends on 19) The filter element of claim 19, wherein said filter element further comprises a diffusion layer positioned between said aramid fiber sheet and said pervious, hollow tube. ### Claim 21 (depends on 20) The filter element of claim 20, wherein said filter element further comprises at least two aramid fiber sheets and at least one diffusion layer positioned between at least two successive aramid fiber sheets. ### Claim 22 A filter element comprising an aramid fiber sheet having a titer reduction of about 10.sup.5 or more against Pseudomonas diminuta helically wrapped around a pervious, hollow tube to form an overlap of 0% to about 95% of the width of said aramid fiber sheet. ### Claim 23 (depends on 22) The filter element of claim 22, wherein said filter element further comprises a diffusion layer positioned between said aramid fiber sheet and said pervious, hollow tube. ### Claim 24 (depends on 23) The filter element of claim 23, wherein said filter element further comprises at least two aramid fiber sheets and at least one diffusion layer positioned between at least two successive aramid fiber sheets. ### Claim 25 (depends on 1) The method of claim 1, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 2 or less. ### Claim 26 (depends on 25) The method of claim 25, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 1.6 or less. ### Claim 27 (depends on 1) The method of claim 1, wherein said aramid fiber sheet has a 1500 cc/min bubble point of about 200 in. water column or more. ### Claim 28 (depends on 27) The method of claim 27, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 2 or less. ### Claim 29 (depends on 28) The method of claim 28, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 1.6 or less. ### Claim 30 (depends on 1) The method of claim 1, wherein said aramid fiber sheet has a thickness of about 20 mils or less. ### Claim 31 (depends on 30) The method of claim 30, wherein said aramid fiber sheet has a thickness of about 10 mils or less. ### Claim 32 (depends on 30) The method of claim 30, wherein said aramid fiber sheet has a sheet weight of about 5 g/ft.sup.2 or less. ### Claim 33 (depends on 32) The method of claim 32, wherein said aramid fiber sheet has a sheet weight of about 4 g/ft.sup.2 or less. ### Claim 34 (depends on 33) The method of claim 33, wherein said aramid fiber sheet has a sheet weight of about 2 g/ft.sup.2 or less. ### Claim 35 (depends on 1) The method of claim 1, wherein said aramid fiber sheet has an air flow resistance of about 100 in. water column or less. ### Claim 36 (depends on 1) The method of claim 1, wherein said aramid fiber sheet has no added binder resin. ### Claim 37 (depends on 5) The method of claim 5, wherein said aramid fiber sheet has a titer reduction of about 10.sup.8 or more against Pseudomonas diminuta. ### Claim 38 (depends on 37) The method of claim 37, wherein said aramid fiber sheet has a titer reduction of about 10.sup.10 or more against Pseudomonas diminuta. ### Claim 39 (depends on 5) The method of claim 5, wherein said aramid fiber sheet has a thickness of about 20 mils or less. ### Claim 40 (depends on 39) The method of claim 39, wherein said aramid fiber sheet has a thickness of about 10 mils or less. ### Claim 41 (depends on 39) The method of claim 39, wherein said aramid fiber sheet has a sheet weight of about 5 g/ft.sup.2 or less. ### Claim 42 (depends on 41) The method of claim 41, wherein said aramid fiber sheet has a sheet weight of about 4 g/ft.sup.2 or less. ### Claim 43 (depends on 42) The method of claim 42, wherein said aramid fiber sheet has a sheet weight of about 2 g/ft.sup.2 or less. ### Claim 44 (depends on 5) The method of claim 5, wherein said aramid fiber sheet has an air flow resistance of about 100 in. water column or less. ### Claim 45 (depends on 5) The method of claim 5, wherein said aramid fiber sheet has no added binder resin. ### Claim 46 A filter element comprising an aramid fiber sheet having a first bubble point of about 100 in. water column or more. ### Claim 47 (depends on 46) The filter element of claim 46, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 2 or less. ### Claim 48 (depends on 47) The filter element of claim 47, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 1.6 or less. ### Claim 49 (depends on 46) The filter element of claim 46, wherein said aramid fiber sheet has a 1500 cc/min bubble point of about 200 in. water column or more. ### Claim 50 (depends on 49) The filter element of claim 49, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 2 or less. ### Claim 51 (depends on 50) The filter element of claim 50, wherein said aramid fiber sheet has a ratio of 1500 cc/min bubble point to first bubble point of about 1.6 or less. ### Claim 52 (depends on 46) The filter element of claim 46, wherein said aramid fiber sheet has a thickness of about 20 mils or less. ### Claim 53 (depends on 52) The filter element of claim 52, wherein said aramid fiber sheet has a thickness of about 10 mils or less. ### Claim 54 (depends on 52) The filter element of claim 52, wherein said aramid fiber sheet has a sheet weight of about 5 g/ft.sup.2 or less. ### Claim 55 (depends on 54) The filter element of claim 54, wherein said aramid fiber sheet has a sheet weight of about 4 g/ft.sup.2 or less. ### Claim 56 (depends on 55) The filter element of claim 55, wherein said aramid fiber sheet has a sheet weight of about 2 g/ft.sup.2 or less. ### Claim 57 (depends on 46) The filter element of claim 46, wherein said aramid fiber sheet has an air flow resistance of about 100 in. water column or less. ### Claim 58 (depends on 46) The filter element of claim 46, wherein said aramid fiber sheet has no added binder resin. ### Claim 59 A filter element comprising an aramid fiber sheet having a titer reduction of about 10.sup.5 or more against Pseudomonas diminuta. ### Claim 60 (depends on 59) The filter element of claim 59, wherein said aramid fiber sheet has a titer reduction of about 10.sup.8 or more against Pseudomonas diminuta. ### Claim 61 (depends on 60) The filter element of claim 60, wherein said aramid fiber sheet has a titer reduction of about 10.sup.10 or more against Pseudomonas diminuta. ### Claim 62 (depends on 59) The filter element of claim 59, wherein said aramid fiber sheet has a thickness of about 20 mils or less. ### Claim 63 (depends on 62) The filter element of claim 62, wherein said aramid fiber sheet has a thickness of about 10 mils or less. ### Claim 64 (depends on 62) The filter element of claim 62, wherein said aramid fiber sheet has a sheet weight of about 5 g/ft.sup.2 or less. ### Claim 65 (depends on 63) The filter element of claim 63, wherein said aramid fiber sheet has a sheet weight of about 4 g/ft.sup.2 or less. ### Claim 66 (depends on 64) The filter element of claim 64, wherein said aramid fiber sheet has a sheet weight of about 2 g/ft.sup.2 or less. ### Claim 67 (depends on 59) The filter element of claim 59, wherein said aramid fiber sheet has an air flow resistance of about 100 in. water column or less. ### Claim 68 (depends on 59) The filter element of claim 59, wherein said aramid fiber sheet has no added binder resin.