Multi-phase filter medium

Abstract

Multi-phase filter media, as well as related articles, components, filter elements, and methods, are disclosed.

1 . (canceled) 
     
     
         2 . A method of forming an article, comprising:
 disposing through a wet laid process a first dispersion containing first and second pluralities of fibers in a first solvent onto a wire for forming a first phase;   while the first plurality of fibers and second plurality of fibers are on the wire, disposing a second dispersion containing third and fourth pluralities of fibers in a second solvent onto the first and second pluralities of fibers for forming a second phase;   at least partially removing the first and second solvents, thereby forming an article comprising the first and second phases,   wherein the first phase has a lower air permeability than the second phase,   wherein the air permeability of the first plurality of fibers is higher than the air permeability of the second plurality of fibers, wherein the air permeability of the third plurality of fibers is higher than the air permeability of the fourth plurality of fibers,   wherein the first plurality of fibers are made from an organic polymeric material, and   wherein a weight ratio of the first plurality of fibers to the second plurality of fibers in the article is from about 50:50 to about 97:3,   wherein the basis weight ratio of the first phase to the second phase is from about 30:70 to about 70:30, and   wherein the article is configured as a filter medium.   
     
     
         3 . A method of forming an article, comprising:
 disposing through a wet laid process a first dispersion containing first and second pluralities of fibers in a first solvent onto a wire for forming a first phase;   while the first plurality of fibers and second plurality of fibers are on the wire, disposing a second dispersion containing third and fourth pluralities of fibers in a second solvent onto the first and second pluralities of fibers for forming a second phase;   applying a vacuum to the first and second dispersions to remove at least portions of the first and second solvents, thereby forming an article comprising the first and second phases,   wherein the air permeability of the first plurality of fibers is higher than the air permeability of the second plurality of fibers, wherein the air permeability of the third plurality of fibers is higher than the air permeability of the fourth plurality of fibers,   wherein the first plurality of fibers are made from an organic polymeric material, and   wherein a weight ratio of the first plurality of fibers to the second plurality of fibers in the article is from about 50:50 to about 97:3,   wherein the basis weight ratio of the first phase to the second phase is from about 30:70 to about 70:30, and   wherein the article is configured as a filter medium.   
     
     
         4 . A method of forming an article, comprising:
 disposing through a wet laid process a first dispersion containing first and second pluralities of fibers in a first solvent onto a wire for forming a first phase;   while the first plurality of fibers and second plurality of fibers are on the wire, disposing a second dispersion containing third and fourth pluralities of fibers in a second solvent onto the first and second pluralities of fibers for forming a second phase;   at least partially removing the first and second solvents, thereby forming an article comprising the first and second phases,   wherein the first phase has a lower air permeability than the second phase,   wherein the basis weight ratio of the first phase to the second phase is from about 30:70 to about 70:30,   wherein the article is configured as a filter medium, and   wherein the filter medium has a mean flow pore size of at least about 25 microns and at most about 1,000 microns.   
     
     
         5 . The method of  claim 2 , wherein the air permeability of the first or third plurality of fibers is from about 50 CFM to about 350 CFM. 
     
     
         6 . The method of  claim 2 , wherein the air permeability of the second or fourth plurality of fibers is from about 5 CFM to about 50 CFM. 
     
     
         7 . The method of  claim 2 , wherein the article includes a weight ratio of the first and second pluralities of fibers of from about 50:50 to about 90:10, and a weight ratio of the third and fourth pluralities of fibers of from about 10:90 to about 50:50. 
     
     
         8 . The method of  claim 2 , wherein the first or third plurality of fibers have an average fiber length of from about 1.5 mm to about 6 mm. 
     
     
         9 . The method of  claim 2 , wherein the second or fourth plurality of fibers have an average fiber length of from about 0.5 mm to about 2 mm. 
     
     
         10 . The method of  claim 2 , wherein the first or third plurality of fibers comprise softwood fibers, cotton fibers, polyester fibers, polyvinyl alcohol binder fibers, or rayon fibers, and the second or fourth plurality of fibers comprise hardwood fibers, polyethylene fibers, or polypropylene fibers. 
     
     
         11 . The method of  claim 10 , wherein the first or third plurality of fibers comprise softwood fibers, and the second or fourth plurality of fibers comprise hardwood fibers. 
     
     
         12 . The method of  claim 2 , wherein the article has a mean flow pore size of from about 3 microns to about 1,000 microns. 
     
     
         13 . The method of  claim 2 , wherein the article has a mean flow pore size of from about 25 microns to about 125 microns. 
     
     
         14 . The method of  claim 2 , wherein the article has a mean flow pore size of from about 25 microns to about 1,000 microns. 
     
     
         15 . The method of  claim 2 , wherein the article has a dust holding capacity from about 0.3 g to about 3 g measured according to a Palas flat sheet test. 
     
     
         16 . The method of  claim 2 , wherein the third pluralities of fibers are made from an organic polymeric material. 
     
     
         17 . The method of  claim 2 , wherein the article comprises an interface between the first and second phases that is substantially free of an adhesive. 
     
     
         18 . The method of  claim 2 , wherein the first plurality of fibers are hardwood or softwood fibers, and the fourth plurality of fibers are hardwood or softwood fibers. 
     
     
         19 . The method of  claim 2 , wherein the article has an air permeability of between about 2 CFM and about 160 CFM. 
     
     
         20 . The method of  claim 2 , wherein the article has a transition phase between the first and second phases, wherein the transition phase comprises at least a portion of the first plurality of fibers, at least a portion of the second plurality of fibers, at least a portion of the third plurality of fibers, and at least a portion of the fourth plurality of fibers, and wherein at least a portion of the first plurality of fibers, at least a portion of the second plurality of fibers, at least a portion of the third plurality of fibers, and at least a portion of the fourth plurality of fibers are intermingled with each other. 
     
     
         21 . The method of  claim 2 , wherein the step of at least partially removing the first and second solvents comprises applying a vacuum to the first and second dispersions to remove at least portions of the first and second solvents simultaneously.