초록 ▼

It is an object of the present invention to provide a separation membrane in which a film-forming solution can be prevented from reaching a rear surface of a porous support in a step of forming a film, the adhesion between a functional film for separation and the porous support is high, and the thic

It is an object of the present invention to provide a separation membrane in which a film-forming solution can be prevented from reaching a rear surface of a porous support in a step of forming a film, the adhesion between a functional film for separation and the porous support is high, and the thickness can be reduced. In the present invention, the separation membrane includes a porous support having a rough rear surface and a functional film for separation, and the functional film is disposed on a front surface of the porous support and extends into the porous support.

대표청구항 ▼

The invention claimed is: 1. A separation membrane comprising a functional film for separation and a woven or non-woven fabric porous support having a rough rear surface and having no substantial separation function, wherein the rear region of the porous support has an average density less than tha

The invention claimed is: 1. A separation membrane comprising a functional film for separation and a woven or non-woven fabric porous support having a rough rear surface and having no substantial separation function, wherein the rear region of the porous support has an average density less than that of a region of the front surface, the functional film comprises a microporous support sheet and a layer that is substantially responsible for performing membrane separation, the functional film is disposed on a front surface of the porous support, and the functional film extends into the porous support but not to the outermost portions of the rear surface. 2. The separation membrane according to claim 1, wherein the rear surface of the porous support has a large number of dents and the functional film extends to the dents of the rear surface of the porous support and is attached to the dents. 3. The separation membrane according to claim 1, wherein a region extending from the rear surface of the porous support to a depth equal to 50% of the total thickness has an average density ranging from 5% to 90% of that of a region extending from the front surface of the porous support to a depth equal to 50% of the total thickness, wherein the average density represents the percentage of the cross-sectional area of the porous support in the area of a measurement section when the porous support is cut perpendicular to a surface. 4. The separation membrane according to claim 1, wherein the functional film extends to the region extending from the rear surface of the porous support to a depth equal to 50% of the total thickness. 5. The separation membrane according to claim 1, wherein the porous support is processed by high-pressure thermal treatment. 6. The separation membrane according to claim 1, wherein the rear surface of the porous support has a smoothness ranging from 1 to 20 s, the smoothness being determined according to JIS P8119. 7. The separation membrane according to claim 6, wherein the rear surface of the porous support has a smoothness ranging from 5 to 20 s, the smoothness being determined according to JIS P8119. 8. The separation membrane according to claim 1, wherein the porous support has a thickness ranging from 40 to 150 μm. 9. The separation membrane according to claim 8, wherein the porous support has a thickness ranging from 40 to 80 μm. 10. A separation membrane element comprising the separation membrane according to claim 1, a permeate carrier, a feed spacer, and a permeate core tube, wherein the separation membrane is spiral-wound around the permeate core tube together with the permeate carrier and the feed spacer. 11. A separation membrane module comprising the separation membrane element according to claim 10 and a pressure vessel, wherein the element is placed in the vessel. 12. The separation membrane according to claim 1, wherein the layer that is substantially responsible for performing membrane separation is a semipermeable membrane comprising polyamide, polyimide or cellulose acetate. 13. The separation membrane according to claim 5, wherein the high-pressure thermal treatment comprises one of embossing and calendering. 14. A separation membrane comprising a functional film for separation and a woven or non-woven fabric porous support having a rough rear surface and having no substantial separation function, wherein the porous support has a region of the rear surface whose density is less than that of a region of the front surface, the functional film comprises a microporous support sheet and a layer that is substantially responsible for performing membrane separation, the functional film is disposed on a front surface of the porous support and extends into the porous support, wherein the rear surface of the porous support has a large number of dents, and wherein the functional film extends to the dents of the rear surface of the porous support and is attached to the dents. 15. The separation membrane according to claim 14, wherein the rear surface of the porous support is rendered rough by high-pressure thermal treatment. 16. The separation membrane according to claim 15, wherein the high-pressure thermal treatment comprises calendering, and wherein the smoothness of the porous support is controlled by adjusting the surface temperature of two rolls between which the porous support is placed and by adjusting the contact time between the porous support and the two rolls. 17. The separation membrane according to claim 14, wherein the rear surface of the porous support has a smoothness of 1 to 20 s, according to JIS P8119. 18. A separation membrane comprising a functional film for separation and a woven or non-woven fabric porous support having a rough rear surface and having no substantial separation function, wherein the porous support has a region of the rear surface whose density is less than that of a region of the front surfaces, the functional film comprises a microporous support sheet and a layer that is substantially responsible for performing membrane separation, the functional film is disposed on a front surface of the porous support and extends into the porous support, wherein the rear surface of the porous support has a large number of dents, and wherein the functional film extends to the dents of the rear surface of the porous support and is attached to the dents but does not extend to the outermost portions of the rear surface, thus preventing defects in the separation membrane.