Pre-metered, unsupported multilayer microporous membrane

Abstract

An at least two layer, unsupported, continuous microporous membrane is disclosed. The at least two layer, unsupported, continuous microporous membrane may include at least two different membrane pore size layers or the pore sizes may have about the same pore size. Apparatus and processes for fabricating at least a two layer unsupported, continuous, microporous membrane are also disclosed. One representative process disclosed for forming a continuous, unsupported, multilayer phase inversion microporous membrane having at least two layers comprises of the acts of: operatively positioning at least one dope applying apparatus, having at least two polymer dope feed slots, relative to a continuous moving coating surface; applying polymer dopes from each of the dope feed slots onto the continuously moving coating surface so as to create a multiple layer polymer dope coating on the coating surface; subjecting the multiple dope layer to contact with a phase inversion producing environment so as to form a wet multilayer phase inversion microporous membrane; and then washing and drying the membrane. Other representative apparatuses and processes are also disclosed.

1 . A process of forming multilayered microporous structures comprising the steps of: 
 a. preparing two or more solutions of a polymer and a solvent for said polymer,    b. premetered-hydrodynamic equilibrium applying two or more solutions onto a support,    c. effecting a phase separation of the two or more solutions and,    d. separating the microporous multilayered structure from the support.    
   
   
       2 . The process of  claim 1  further comprising after the premetered-hydrodynamic equilibrium step of (b) but for effecting a phase separation of step (c), subjecting at least one of the solutions to heating to attain a predetermined temperature in said solution.  
   
   
       3 . The process of  claim 1  further comprising extracting the remaining components of the solvent system from the separated microporous structure.  
   
   
       4 . The process of  claim 1  further comprising drying the separated microporous polymer structure.  
   
   
       5 . The process of  claim 1  wherein each polymer solution is a homogenous solution.  
   
   
       6 . The process of  claim 1  wherein at least one of the two or more polymer solutions is a homogenous solution.  
   
   
       7 . The process of  claim 1  further comprising at least one of the two or more solutions contains one or more components that are non-solvents for said polymer solutions.  
   
   
       8 . A process of forming multilayered microporous structures comprising the steps of: 
 a. preparing two or more solutions of a polymer and a solvent for said polymer,    b. premetered-hydrodynamic equilibrium applying two or more solutions onto one surface of a support having an opposing surface which is not coated,    c. effecting a phase separation of the two or more solutions and,    d. recovering the microporous multilayered structure.    
   
   
       9 . The process of  claim 8  further comprising after the premetered-hydrodynamic equilibrium step of (b) but for effecting a phase separation of step (c), subjecting at least one of the solutions to heating to attain a predetermined temperature in said solution.  
   
   
       10 . The process of  claim 8  further comprising extracting the remaining components of the solvent system from the recovered microporous structure.  
   
   
       11 . The process of  claim 8  further comprising drying the recovered microporous polymer structure.  
   
   
       12 . The process of  claim 8  wherein each polymer solution is a homogenous solution.  
   
   
       13 . The process of  claim 8  wherein at least one of the two or more polymer solutions is a homogenous solution.  
   
   
       14 . The process of  claim 8  further comprising at least one of the two or more solutions contains one or more components that are non-solvents for said polymer solutions.