Filtration media and methods of preparation

Abstract

Provided are methods of preparing filtration media in which a microporous layer is coated on a temporary carrier substrate and a porous substrate is then laminated to the microporous layer, after or prior to removing the temporary carrier substrate from the microporous layer. Preferably, the microporous layer comprises one or more microporous xerogel layers. Also provided are filtration media prepared by such methods.

1 . Filtration media comprising a microporous layer, wherein said filtration media is prepared according to a method comprising the steps of: 
 (a) coating a microporous layer on a temporary carrier substrate to form a microporous layer assembly, wherein said microporous layer has a first surface in contact with said temporary carrier substrate and has a second surface on the side opposite from said temporary carrier substrate;    (b) laminating said microporous layer assembly on the side opposite from said temporary carrier substrate to a porous substrate to form a porous substrate/microporous layer assembly;    (c) removing said temporary carrier substrate from said first surface of said microporous layer.    
   
   
       2 . The filtration media of  claim 1 , wherein said microporous layer comprises one or more microporous xerogel layers formed by drying a liquid metal oxide sol to form a xerogel layer of a solid metal oxide gel matrix with pores which are interconnected in a continuous fashion from one outermost surface of said xerogel layer through to the other outermost surface of said xerogel layer.  
   
   
       3 . The filtration media of  claim 1 , wherein said microporous layer comprises one or more microporous metal oxide xerogel layers, wherein said microporous metal oxide xerogel layers are continuous xerogel coating layers with said metal oxides in a continuous structure in said xerogel coating layers.  
   
   
       4 . The filtration media of  claim 2 , wherein at least one of said one or more microporous xerogel layers comprises a material selected from the group consisting of pseudo-boehmites, zirconium oxides, titanium oxides, aluminum oxides, silicon oxides, and tin oxides.  
   
   
       5 . The filtration media of  claim 2 , wherein said liquid metal oxide sol comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       6 . The filtration media of  claim 3 , wherein at least one of said one or more microporous metal oxide xerogel layers comprises a material selected from the group consisting of pseudo-boehmites, zirconium oxides, titanium oxides, aluminum oxides, silicon oxides, and tin oxides.  
   
   
       7 . The filtration media of  claim 3 , wherein at least one of said one or more microporous metal oxide xerogel layers comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       8 . The filtration media of  claim 1 , wherein said microporous layer comprises a discontinuous layer that is not a xerogel coating layer and has discontinuities of solid pigment particles that are separated from each other in the structure of said discontinuous layer.  
   
   
       9 . The filtration media of  claim 8 , wherein said discontinuous layer comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       10 . The filtration media of  claim 1 , wherein said temporary carrier substrate is a flexible web substrate.  
   
   
       11 . The filtration media of  claim 10 , wherein said flexible web substrate is selected from the group consisting of papers, polymeric films, and metals.  
   
   
       12 . The filtration media of  claim 10 , wherein said flexible web substrate is surface treated with a release agent.  
   
   
       13 . Filtration media comprising a microporous layer, wherein said filtration media is prepared according to a method comprising the steps of: 
 (a) coating a microporous layer on a temporary carrier substrate to form a microporous layer assembly, wherein said microporous layer has a first surface in contact with said temporary carrier substrate and has a second surface on the side opposite from said temporary carrier substrate;    (b) coating an overlying layer on said microporous layer assembly on the side opposite from said temporary carrier substrate;    (c) laminating said overlying layer to a porous substrate to form a porous substrate/microporous layer assembly;    (d) removing said temporary carrier substrate from said first surface of said microporous layer.    
   
   
       14 . The filtration media of  claim 13 , wherein said microporous layer comprises one or more microporous xerogel layers formed by drying a liquid metal oxide sol to form a xerogel layer of a solid metal oxide gel matrix with pores which are interconnected in a continuous fashion from one outermost surface of said xerogel layer through to the other outermost surface of said xerogel layer.  
   
   
       15 . The filtration media of  claim 13 , wherein said microporous layer comprises one or more microporous metal oxide xerogel layers, wherein said microporous metal oxide xerogel layers are continuous xerogel coating layers with said metal oxides in a continuous structure in said xerogel coating layers.  
   
   
       16 . The filtration media of  claim 14 , wherein at least one of said one or more microporous xerogel layers comprises a material selected from the group consisting of pseudo-boehmites, zirconium oxides, titanium oxides, aluminum oxides, silicon oxides, and tin oxides.  
   
   
       17 . The filtration media of  claim 14 , wherein said liquid metal oxide sol comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       18 . The filtration media of  claim 15 , wherein at least one of said one or more microporous metal oxide xerogel layers comprises a material selected from the group consisting of pseudo-boehmites, zirconium oxides, titanium oxides, aluminum oxides, silicon oxides, and tin oxides.  
   
   
       19 . The filtration media of  claim 15 , wherein at least one of said one or more microporous metal oxide xerogel layers comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       20 . The filtration media of  claim 13 , wherein said microporous layer comprises a discontinuous layer that is not a xerogel coating layer and has discontinuities of solid pigment particles that are separated from each other in the structure of said discontinuous layer.  
   
   
       21 . The filtration media of  claim 20 , wherein said discontinuous layer comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       22 . The filtration media of  claim 13 , wherein said temporary carrier substrate is a flexible web substrate.  
   
   
       23 . The filtration media of  claim 22 , wherein said flexible web substrate is selected from the group consisting of papers, polymeric films, and metals.  
   
   
       24 . The filtration media of  claim 22 , wherein said flexible web substrate is surface treated with a release agent.  
   
   
       25 . Filtration media comprising a microporous layer, wherein said filtration media is prepared according to a method comprising the steps of: 
 (a) coating a microporous layer on a temporary carrier substrate to form a microporous layer assembly, wherein said microporous layer has a first surface in contact with said temporary carrier substrate and has a second surface on the side opposite from said temporary carrier substrate;    (b) removing said temporary carrier substrate from said first surface of said microporous layer to form a free standing microporous layer;    (c) laminating said free standing microporous layer to a porous substrate.    
   
   
       26 . The filtration media of  claim 25 , wherein said microporous layer comprises one or more microporous xerogel layers formed by drying a liquid metal oxide sol to form a xerogel layer of a solid metal oxide gel matrix with pores which are interconnected in a continuous fashion from one outermost surface of said xerogel layer through to the other outermost surface of said xerogel layer.  
   
   
       27 . The filtration media of  claim 25 , wherein said microporous layer comprises one or more microporous metal oxide xerogel layers, wherein said microporous metal oxide xerogel layers are continuous xerogel coating layers with said metal oxides in a continuous structure in said xerogel coating layers.  
   
   
       28 . The filtration media of  claim 26 , wherein at least one of said one or more microporous xerogel layers comprises a material selected from the group consisting of pseudo-boehmites, zirconium oxides, titanium oxides, aluminum oxides, silicon oxides, and tin oxides.  
   
   
       29 . The filtration media of  claim 26 , wherein said liquid metal oxide sol comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       30 . The filtration media of  claim 27 , wherein at least one of said one or more microporous metal oxide xerogel layers comprises a material selected from the group consisting of pseudo-boehmites, zirconium oxides, titanium oxides, aluminum oxides, silicon oxides, and tin oxides.  
   
   
       31 . The filtration media of  claim 27 , wherein at least one of said one or more microporous metal oxide xerogel layers comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       32 . The filtration media of  claim 25 , wherein said microporous layer comprises a discontinuous layer that is not a xerogel coating layer and has discontinuities of solid pigment particles that are separated from each other in the structure of said discontinuous layer.  
   
   
       33 . The filtration media of  claim 32 , wherein said discontinuous layer comprises a binder selected from the group consisting of organic polymer binders and inorganic binders.  
   
   
       34 . The filtration media of  claim 25 , wherein said temporary carrier substrate is a flexible web substrate.  
   
   
       35 . The filtration media of  claim 34 , wherein said flexible web substrate is selected from the group consisting of papers, polymeric films, and metals.  
   
   
       36 . The filtration media of  claim 34 , wherein said flexible web substrate is surface treated with a release agent.