Composite filter medium and fluid filters containing same

Abstract

A composite filter medium for removing at least 99.95 percent of particulates of a size in the 3 to 4 micron range and dissolved chemical contaminants from a fluid and filters of various configurations employing the composite filter medium are disclosed. The composite filter medium comprises an adsorbent layer containing an adsorbent agent and a hydrophilic particulate intercepting layer disposed adjacent to the adsorbent layer. The composite medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point of about 3 to 15 microns and an air permeability of about 0.5 to 7 liters per minute/cm 2 with a pressure drop of about 0.1 bar.

1 . A low flow resistance composite filter medium for removing at least 99.95 percent of particulates at a size in the 3 to 4 micron range and dissolved chemical contaminants from a fluid, the composite filter medium comprising: 
 an adsorbent layer containing at least one adsorbent agent;    a hydrophilic particulate intercepting layer disposed adjacent to the adsorbent layer; and    wherein the composite filter medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point of about 3 to 15 microns and an air permeability of about 0.5 to 7 liters per minute/cm2 with a pressure drop of about 0.1 bar.    
     
     
         2 . The composite filter medium of  claim 1 , wherein the adsorbent layer further comprises an adsorbent supporting web substrate having a surface coated with a mixture of adsorbent particles and binder particles fused to the surface and to the adsorbent particles.  
     
     
         3 . The composite filter medium of  claim 2 , wherein the material forming the adsorbent particle supporting web substrate web is a non-woven fibrous material selected from the group consisting of spun bonded polymers, wet laid fibrous materials and dry laid fibrous materials.  
     
     
         4 . The composite filter medium of  claim 2 , wherein the material forming the adsorbent particles is selected from the group consisting of iodinated resin, activated carbon, activated alumina, alumina-silicates, ion exchange resins, manganese oxide and iron oxide.  
     
     
         5 . The composite filter medium of  claim 2 , wherein the material forming the binder particles is a thermoplastic selected from the group consisting of polyolefins, polypropylene, low density polyethylene, linear low density polyethylene, ethylene vinyl acetate and high density polyethylene.  
     
     
         6 . The composite filter medium of  claim 2 , wherein an overlaying web substrate is provided adjacent to the adsorbent supporting web substrate on its front side and wherein the binder particles are also fused to the overlaying web substrate.  
     
     
         7 . The composite filter medium of  claim 1 , wherein the hydrophilic particulate intercepting layer comprises a fiber supporting web substrate positioned adjacent to the adsorbent layer and a micro fiber and resin mixture disposed between the adsorbent layer and the fiber supporting web substrate.  
     
     
         8 . The composite filter medium of  claim 7 , wherein an intermediate web substrate is disposed between the micro fiber and resin mixture and the adsorbent layer.  
     
     
         9 . The composite filter medium of  claim 7 , wherein the material forming the fiber supporting web substrate web is a non-woven fibrous material selected from the group consisting of spun bonded polymers, wet laid fibrous materials and dry laid fibrous materials.  
     
     
         10 . The composite filter medium of  claim 2 , wherein the hydrophilic particulate intercepting layer comprises a fiber supporting web substrate positioned adjacent to the adsorbent supporting web substrate and a micro fiber and resin mixture disposed between the adsorbent supporting web substrate and the fiber supporting web substrate.  
     
     
         11 . The composite filter medium of  claim 10 , wherein an intermediate web substrate is disposed between the micro fiber and resin mixture and the adsorbent supporting web substrate.  
     
     
         12 . The composite filter medium of  claim 10 , wherein an overlaying web substrate is provided adjacent to the adsorbent supporting web substrate on its front side and wherein the binder particles are also fused to the overlaying web substrate.  
     
     
         13 . The composite filter medium of  claim 12 , wherein an intermediate web substrate is disposed between the micro fiber and resin mixture and the adsorbent supporting web substrate.  
     
     
         14 . The composite filter medium of  claim 13 , wherein the material forming the fiber supporting web substrate web is a non-Woven fibrous material selected from the group consisting of spun bonded polymers, wet laid fibrous materials and dry laid fibrous materials.  
     
     
         15 . The composite filter medium of  claim 1 , wherein the hydrophilic particulate intercepting layer comprises a hydrophilic melt blown micro fiber medium.  
     
     
         16 . The composite filter medium of  claim 2 , wherein the hydrophilic particulate intercepting layer comprises a hydrophilic melt blown micro fiber medium.  
     
     
         17 . The composite filter medium of  claim 16 , wherein an overlaying web substrate is provided adjacent to the adsorbent supporting web substrate on its front side and wherein the binder particles are also fused to the overlaying web substrate.  
     
     
         18 . The composite filter medium of  claim 1 , wherein the hydrophilic particulate intercepting layer comprises a hydrophilic porous membrane.  
     
     
         19 . The composite filter medium of  claim 2 , wherein the hydrophilic particulate intercepting layer comprises a hydrophilic porous membrane.  
     
     
         20 . The composite filter medium of  claim 19 , wherein an overlaying web substrate is provided adjacent to the adsorbent supporting web substrate on its front side and wherein the binder particles are also fused to the overlaying web substrate.  
     
     
         21 . A filter for removing 99.95 percent of particulates of a size in the 3 to 4 micron range and dissolved chemical contaminants from fluid, the filter comprising: 
 a rim defining a filtration area within the rim;    a sheet-like composite filter medium disposed within the filtration area of the rim and having edges sealably affixed to the rim, wherein the sheet-like composite filter medium further comprises:    an adsorbent layer containing an adsorbent agent;    a hydrophilic particulate intercepting layer disposed adjacent to the adsorbent layer; and    wherein the composite filter medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point of about 3 to 15 microns and an air permeability of about 0.5 to 7 liters per minute/cm 2  with a pressure drop of about 0.1 bar; and    at least one support member extending from the rim into the filtration area.    
     
     
         22 . The filter of  claim 21 , wherein a portion of the rim on an outlet side of the filter medium is provided with a groove for sealably engaging with the rim of a container.  
     
     
         23 . The filter of  claim 22 , wherein the rim is formed from a resiliently deformable material.  
     
     
         24 . A cylindrical pleated filter for removing 99.95 percent of particulates of a size in the 3 to 4 micron range and dissolved chemical contaminants from fluid, the filter comprising: 
 a base having an outlet opening therein;    a top;    a fluid permeable tube extending from the base to the top, the tube having an end engaged with the outlet opening in the base;    a sheet-like composite filter medium sealably disposed in a generally cylindrical configuration about the porous tube between the base and top, the medium further having a plurality of outer radial pleats extending from the base to the top and a plurality of inner radial pleats adjacent to the tube, the outer and inner radial pleats defining a plurality of filtration panels, and wherein the composite filter medium further comprises:    an adsorbent layer containing an adsorbent agent;    a hydrophilic particulate intercepting layer disposed adjacent to the adsorbent layer; and    wherein the medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point of about 3 to 15 microns and an air permeability of about 0.5 to 7 liters per minute/cm 2  with a pressure drop of about 0.1 bar    
     
     
         25 . A spiral wound filter for removing 99.95 percent of particulates of a size in the 3 to 4 micron range and dissolved chemical contaminants from a fluid, the filter comprising: 
 a top having a plurality of perforations therein;    a bottom having a plurality of perforations therein;    a support tube extending from the top to the bottom;    a sheet-like composite filter medium having a top edge adjacent to the top and a bottom edge adjacent to the bottom and being spirally wound around the support tube, wherein the composite filter medium further comprises:    an adsorbent layer containing an adsorbent agent;    a hydrophilic particulate intercepting layer disposed adjacent to the adsorbent layer; and    wherein the medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point of about 3 to 15 microns and an air permeability of about 0.5 to 7 liters per minute/cm 2  with a pressure drop of about 0.1 bar.    
     
     
         26 . The filter according to  claim 25 , wherein alternating edges of the spiral wound filter medium are provided with a barrier to force fluid to flow through the composite filter medium before exiting the filter.  
     
     
         27 . A pleated panel filter for removing 99.95 percent of particulates of a size in the 3 to 4 micron range and dissolved chemical contaminants from a fluid, the filter comprising: 
 an outlet end panel having an opening therein;    a sheet-like composite filter medium capable of sealably covering the opening of the outlet end panel, wherein the sheet-like composite filter medium is pleated so as to have a first outward pleat located remotely from the outlet end panel, an inward pleat located closely to the outlet end panel, and a second outward pleat located remotely from the outlet end panel, wherein the pleats define four filter medium panels comprising a first panel extending between the outlet end panel and the first outward pleat, a panel extending from the first outward pleat to the inward pleat, a third panel extending from the inward pleat to the second outward pleat and a fourth panel extending from the second outward pleat to the outlet end panel, wherein the composite filter medium further comprises:    an adsorbent layer containing an adsorbent agent;    a hydrophilic particulate intercepting layer disposed adjacent to the adsorbent layer; and    wherein the medium has a mean flow pore diameter of about 1 to 10 microns, a bubble point of about 3 to 15 microns and an air permeability of about 0.5 to 7 liters per minute/cm 2  with a pressure drop of about 0.1 bar.    
     
     
         28 . The filter according to  claim 27 , wherein the filter is further provided with at least one drainage support member disposed between adjacent filter medium panels.  
     
     
         29 . The filter according to  claim 28 , wherein the drainage support member comprises a sheet having a plurality of elongated ribs extending therefrom and a plurality of apertures disposed between the elongated ribs.  
     
     
         30 . The filter according to  claim 27 , wherein the filter is further provided with a first drainage support member disposed between the first and second filter medium panels, a second drainage support member disposed between the second and third filter medium panels and a third drainage support member disposed between the third and fourth filter medium panels.  
     
     
         31 . The filter according to  claim 27 , wherein the filter is further provided with a frame extending from the outlet end panel and wherein the filter medium includes at least one edge supported by the frame.  
     
     
         32 . A filtration device comprising: 
 an unfiltered fluid inlet surface, through which unfiltered fluid may enter the filtration device;    a first filter media in fluid communication with said unfiltered fluid inlet surface, said first filter media being spirally wound and being positioned with respect to said unfiltered fluid inlet surface so that unfiltered fluid entering the filtration device through said unfiltered fluid inlet surface is directed to flow radially inward and through said first filter media;    a core in fluid communication with said first filter media, said core having a surface that defines apertures, said core being positioned with respect to said spirally wound first filter media so that filtered fluid flowing radially inward from said first filter media flows into said core, said core having a first end and a second end with the first end being open so that filtered fluid may exit the core and with the second end being closed so that the flow of fluid through the second end is prevented; and    a filtered fluid outlet in fluid communication with the first end of said core so that filtered fluid flowing from the first end of said core exits the filtration device through said filtered fluid outlet.    
     
     
         33 . A filtration device comprising: 
 an unfiltered fluid inlet, through which unfiltered fluid may enter the filtration device;    a core in fluid communication with said unfiltered fluid inlet, said core having a surface defining apertures therein so that unfiltered fluid may flow from said unfiltered fluid inlet and radially outward through said core, said core having a first end and a second end, wherein the first end is open so that unfiltered fluid may enter said core and wherein the second end is closed so that flow of fluid through the second end is prevented;    a first filter media in fluid communication with said core, said filter media being spirally wound around the surface of said core so that fluid flowing from said core may flow radially outward through the apertures and into said first filter media; and    a filtered fluid outlet surface in fluid communication with said first filter media so that filtered fluid from said first filter media may exit the filtration device through said filtered fluid outlet surface.    
     
     
         34 . A filtration device comprising: 
 a housing defining an interior volume, an inlet for allowing fluid to be filtered to enter the volume, and an outlet for filtered fluid to exit the volume;    a core located within the volume, said core defining a chamber, at least one aperture allowing fluid communication through said core and into the chamber, and an exit orifice in fluid communication with the outlet; and    a spirally wound filtration media located within the volume and configured so that fluid entering the volume from the inlet directed to flow radially inward and through the filtration media, through said core, and into the chamber and out of the outlet.    
     
     
         35 . A multistage filter comprising: 
 an inlet for liquid flow and an outlet for liquid flow;    a first filter stage in fluid communication with said inlet, said first filter stage comprising a material that removes microorganisms;    a second filter stage in fluid communication with said outlet, said second filter stage comprising activated carbon; and    said second filter stage being located at a position that allows liquid to pass through said first filter stage, prior to passing through said second filter stage.    
     
     
         36 . A multistage process for filtering impurities from a liquid, said process comprising the steps of: 
 supplying liquid to a filter;    removing at least a portion of the microorganisms from said liquid supply in a first filtering step; and    then removing at least a portion of the organics and other non-biological components in a second filtering step using activated carbon.    
     
     
         37 . A multistage liquid filter, comprising: 
 an inlet for liquid flow and an outlet for liquid flow;    a first filter stage in fluid communication with said inlet, said first filter stage comprising a material that removes microorganisms; and    a second filter stage in fluid communication with said outlet, said second filter stage comprising activated carbon, said second filter stage being located at a position that allows liquid to pass through said first filter stage prior to passing through said second filter stage.