Surface-treated porous materials having filtration properties and methods of preparing them
The present invention is directed to surface-treated membranes comprising: (a) a porous substrate; and (b) a coating layer applied to the substrate. The coating layer is formed from a surface treatment composition comprising: (i) a first component comprising an organic solvent; and (ii) a second component comprising a fluorine-containing polymer and a solvent containing at least one C—F bond. The present invention is further drawn to a method of preparing a surface-treated filtration membrane, comprising: (a) contacting a porous substrate with a first component of a surface treatment composition, wherein the first component comprises an organic solvent; (b) subsequently contacting the porous substrate with a second component of the surface treatment composition, wherein the second component comprises a fluorine-containing polymer and a solvent containing at least one C—F bond; and (c) subjecting the porous substrate to a temperature of 25 to 90° C. for 1 to 180 minutes.
1 . A method of preparing a surface-treated filtration membrane comprising:
(a) contacting a porous polymeric substrate with a first component of a surface treatment composition, wherein the first component comprises an organic solvent having a boiling point less than or equal to 100° C. at atmospheric pressure and which comprises t-butyl acetate;
(b) subsequently contacting the porous polymeric substrate with a second component of the surface treatment composition, wherein the second component comprises:
(1) a fluorine-containing polymer;
(2) a solvent containing at least one C—F bond, wherein the solvent (2) is different from the organic solvent in the first component; and
(3) the organic solvent having a boiling point less than or equal to 100° C. at atmospheric pressure that is also present in the first component; and
(c) subjecting the porous polymeric substrate to a temperature of 25 to 90° C. for 1 to 180 minutes to form a surface-treated filtration membrane.
2 . The method of claim 1 , wherein the substrate comprises an air filter.
3 . The method of claim 1 , wherein the organic solvent in the first component has a boiling point of at least 50° C. at atmospheric pressure.
4 . The method of claim 1 , wherein the fluorine-containing polymer (1) comprises a (meth)acrylic polymer and/or a copolymer of at least two of vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene and perfluoromethylvinyl ether.
5 . The method of claim 4 , wherein the fluorine-containing polymer (1) is prepared from a reaction mixture comprising a mixture of fluoro-functional monomers, wherein the mixture of fluoro-functional monomers includes at least one ether functional fluorine-containing monomer.