Filtration membranes and method of making the same

A microporous membrane comprising a polyethersulfone polymer of the general formula ##STR8## which in bulk is hydrophobic and has an equilibrium water absorption of about 2% to about 4% and polyvinylpyrrolidone in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions, said membrane being further characterized by remaining hydrophilic after extraction with isopropanol.

A microporous membrane comprising a polyamide-imide polymer which is hydrophobic in bulk form and has an equilibrium water absorption of about 2% to about 4% and is blended with a polymer additive in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions.

A microporous membrane comprising a polyimide polymer which in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4% and which is blended with a polymer additive in an amount effective to make the membrane when formed and dried inherently water wettable, said membrane being further characterized by having a pore size such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions.

A microporous membrane comprising a polyimide polymer which in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4% and which is blended with a polymer additive in an amount effective to make the membrane when formed and dried inherently water wettable, said polymer having the general formula ##STR9## where 10% to 90% of the R groups are ##STR10## and the remaining R groups are ##STR11## said membrane being further characterized by being hydrophilic and having a pore size range such that the membrane does not retain or reject dissolved proteins or salts from feed solutions.

A microporous membrane comprising a polyamide-imide polymer which in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4% and which is blended with a polymer additive in an amount effective to make the membrane when formed and dried inherently water wettable, said polymers having the general formula ##STR12## where R is aromatic, the membrane being further characterized by a pore size range such that the membrane does not retain or reject dissolved proteins or salts from feed solutions.

A process for filtering matter from a solution comprising flowing said solution through a microporous, inherently water wettable membrane comprising a polymer and a polymer additive, which polymer in bulk form is hydrophobic and has a water absorption equilibrium ranging from about 2% to about 4%, the polymer additive in the membrane being in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions.

A process for filtering matter from a solution comprising flowing said solution through a microporous, inherently water wettable membrane comprising a polyethersulfone polymer and a polymer additive, which polymer in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4%, said membrane having a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions, the polymer having the general formula ##STR20## said polymer additive comprising polyvinylpyrrolidone in an amount effective to make the membrane inherently water wettable when dried, said membrane remaining inherently wettable after extraction with isopropanol.

A process for filtering matter from a solution comprising flowing said solution through a microporous, inherently water wettable membrane comprising a polyamide-imide polymer and a polymer additive, which polymer in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4%, said polymer additive being present in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions.

A process for filtering matter from a solution comprising flowing said solution through a microporous, inherently water wettable membrane comprising a polyimide polymer and a polymer additive, which polymer in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4%, said polymer additive being present in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions.

A process for filtering matter from a solution comprising flowing said solution through a microporous, inherently water wettable membrane comprising a polyimide polymer and a polymer additive, which polymer in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4%, the polymer having the general formula ##STR21## where 10% to 90% of R is ##STR22## and the remaining R groups are ##STR23## said polymer additive being present in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions.

A dry filter comprising an inherently water wettable, microporous membrane comprising a polyethersulfone polymer and a polymer additive, which polymer in bulk form is hydrophobic and has an equilibrium water absorption of about 2% to about 4%, the polymer additive comprising polyethylene glycol in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions;

A microporous, inherently water wettable dry membrane comprising a polymer and a polymer additive which polymer is hydrophobic in bulk form and has an equilibrium water absorption of about 2% to about 4%, said polymer additive being blended in an amount effective to make the membrane when formed and dried inherently water wettable, with a pore size range such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions, said polymer additive being selected from polyethyleneglycol and polyvinylpyrrolidone.

A microporous, inherently water wettable dry membrane comprising a polymer which is hydrophobic in bulk form and has an equilibrium water absorption ranging from about 2% to 4% and which is blended with polyvinylpyrrolidone polymer additive in an amount effective to make the membrane when formed and dried inherently water wettable, the pore size range of said formed and dried membrane being such that the membrane does not retain or reject dissolved proteins or salts from aqueous feed solutions.