Strongly acidic microporous membranes for cation exchange
AssigneeGelman Sciences, Inc.
InventorStephen M. Wolpert
Life of this patent
Estimating the term…
Abstract
Microporous filtration membranes are provided which are useful for absorbing or adsorbing cationic atoms, molecules or particles from liquids or gases. The invention also concerns novel strongly acidic copolymer solutions capable of crosslinking, and a process for preparing such solutions and making strongly acidic or anionic charge modified microporous filtration membranes therefrom. The copolymer of the solutions is synthesized from 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and either N-(isobutoxymethyl)acrylamide (IBMA) or 2-hydroxyethyl methacrylate (HEMA).
Claims26
A copolymer solute in a solution for post-treatment of the internal pores of a microporous base membrane comprising a crosslinkable acid copolymer of a strong acid monomer which is an acrylamide alkane sulfonic acid monomer having the formula:
- CH.sub.2 .dbd.C(R)--CO--NH--R'SO.sub.3 --X
- where
- R is hydrogen or a lower alkyl or phenyl group;
- R' is a methylene group or a lower alkyl, lower cycloalkyl, aromatic, or bivalent hydrocarbon group or other bridging group having its valence bonds on different carbon atoms;
- and
- X is hydrogen or sodium, ammonium, organic amine or other salt forming atom or compound,
- and a crosslinkable monomer having hydroxyl crosslinking functionality selected from (1) N-methylolacrylamide alkoxyether compounds and (2) N-methylolacrylamide, hydroxyalkyl acrylates, and hydroxyalkyl methacrylates that are crosslinkable by reaction with aminoplast resins.
An acid copolymer according to claim where the acid monomer is selected from 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-acrylamido-1-propanesulfonic acid, 3-acrylamido-3-butanesulfonic acid, 2-acrylamido-1-ethanesulfonic acid, 3-acrylamido-1-pentanesulfonic acid, and the like.
A process of preparing a crosslinkable acid copolymer for post-treatment of the internal pores of a porous membrane, which comprises
- reacting an acrylamide alkane sulfonic acid monomer having the formula:
- CH.sub.2 .dbd.C(R)--CO--NH--R'--SO.sub.3 --X
- where
- R is hydrogen or a lower alkyl or phenyl group;
- R' is a methylene group or a lower alkyl, lower cycloalkyl, aromatic, or bivalent hydrocarbon group or other bridging group having its valence bonds on different carbon atoms;
- and
- X is hydrogen or sodium, ammonium, organic amine or other salt forming atom or compound,
- with a crosslinkable monomer having hydroxyl crosslinking functionality selected from (1) N-methylolacrylamide alkoxyether compounds and (2) N-methylolacrylamide, hydroxyalkyl acrylates, and hydroxyalkyl methacrylates that are crosslinkable by reaction with aminoplast resins and curing and drying the resulting copolymer;
- and
- diluting the copolymer with a solvent.
A strongly acidic charge modified microporous filter membrane comprising a base membrane having an internal microstructure throughout said base membrane comprising by post-treatment a charge modifying amount of a charge modifying agent bonded by drying and curing from a solvent to substantially all of said base membrane internal microstructure without substantial pore size reduction or pore blockage wherein the charge modifying agent is a crosslinked acid copolymer of a strong acid monomer which is an acrylamide alkane sulfonic acid monomer having the formula:
- CH.sub.2 .dbd.C(R)--CO--NH--R'--SO.sub.3 --X
- where
- R is hydrogen or a lower alkyl or phenyl group;
- R' is a methylene group or a lower alkyl, lower cycloalkyl, aromatic, or bivalent hydrocarbon group or other bridging group having its valence bonds on different carbon atoms;
- and
- X is hydrogen or sodium, ammonium, organic amine or other salt forming atom or compound,
- with a crosslinkable monomer having hydroxyl crosslinking functionality selected from (1) N-methylolacrylamide alkoxyether compounds and (2) N-methylolacrylamide, hydroxyalkyl acrylates, and hydroxyalkyl methacrylates that are crosslinkable by reaction with aminoplast resins.
Dependencies are inferred from the claim text.