Patent ID: 11872531
Assignee: LG CHEM, LTD.
Field: Chemical engineering (Chemistry)
Classification: CPC B | IPC B

Claim 0:
1. A porous fluorine-based resin membrane comprising a plurality of fluorine-based resin fibrils,
wherein a ratio of an average thickness of fibrils in a surface region to an average thickness of fibrils in an inner region of the porous fluorine-based resin membrane is 2.0 to 2.8,
wherein the surface region is a region within 10% of the total thickness of the membrane from the surface of the porous fluorine-based resin membrane, and the inner region is a region excluding the surface region,
wherein the porous fluorine-based resin membrane has a porosity of 70 to 90%,
wherein a heat shrinkage rate of the porous fluorine-based resin membrane is 10% or less, the heat shrinkage calculated according to Equation 2 using a length value in the transverse direction after a heat treatment at 120° C. for 30 minutes, and a length value in the transverse direction before the heat treatment, and
wherein a tensile strength in the machine direction of the porous fluorine-based resin membrane is 60 to 100 MPa and a tensile strength in the transverse direction of the porous fluorine-based resin membrane is 70 to 120 MPa, the machine and transverse directions being measured according to ASTM D 882,, Heat
      ⁢
         
      shrinkage
      ⁢
         
      rate
      ⁢
         
      
       (
       %
       )
      
     
     =
     
      100
      ×
      
       
        [
        
         
          
           
            
             
              
               
                (
                
                 Length
                 ⁢
                    
                 in
                 ⁢
                    
                 transverse
                 ⁢
                    
                 direction
                
               
              
             
             
              
               
                
                 before
                 ⁢
                    
                 heat
                 ⁢
                    
                 treatment
                
                -
                Length
               
              
             
            
           
          
          
           
            
             in
             ⁢
                
             transverse
             ⁢
                
             direction
             ⁢
                
             after
            
           
          
          
           
            
             
              heat
              ⁢
                 
              treatment
             
             )
            
           
          
         
         
          
           
            
             Length
             ⁢
                
             in
             ⁢
                
             transverse
             ⁢
                
             direction
            
           
          
          
           
            
             before
             ⁢
                
             heat
             ⁢
                
             treatment
            
           
          
         
        
        ]
       
       .
      
     
    
   
   
    
     [
     
      Equation
      ⁢
         
      2
     
     ]