Claims
- 1. A process comprising producing a crosslinked composite membrane by the steps of:
- applying a crosslinking solution containing reactants which comprise a water-soluble polysaccharide having a sulfonate group and/or a sulfonic acid group and a polyfunctional melamine compound to a porous base;
- effecting the drying of the crosslinking solution and the crosslinking of the reactants simultaneously to form a skin layer having a crosslinked structure formed by covalent bonds on the porous base; and
- repeating said process steps.
- 2. The process according to claim 1, wherein said process steps are repeated at least twice.
- 3. The process according to claims 1 or 2, wherein the crosslinking solution is applied by immersion or by means of a bar coater, roll or doctor blade.
- 4. The process according to claims 1 or 2, wherein the crossing is effected by heating or irradiation with U.V. rays or electron beams.
- 5. The process according to claim 1, wherein said crosslinking solution has a pH of 6 or below.
- 6. The process according to claim 1, wherein said crosslinking solution has a pH of 4 or below.
- 7. The process according to claim 1, wherein the porous base is an ultrafilter.
- 8. The process according to claim 1, wherein the water-soluble polysaccharide is sulfoethylcellulose or an alkali salt thereof.
- 9. The process according to claim 1, wherein the polyfunctional melamine compound is n-methoxymethylmelamine, n being di to hexa.
- 10. The process according to claim 1, wherein the polyfunctional melamine compound is an n-methylolmelamine, n being di to hexa.
- 11. The process according to claim 1, wherein the polyfunctional melamine compound content is 3 to 60 wt. %.
- 12. The process according to claim 1, wherein the polyfunctional melamine compound content is 10 to 40%.
Priority Claims (2)
Number |
Date |
Country |
Kind |
61-11088 |
Jan 1986 |
JPX |
|
61-11089 |
Jan 1986 |
JPX |
|
Parent Case Info
This is a division of application Ser. No. 07/006151, 01/23/87, now U.S. Pat. No. 4,824,573.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
3993071 |
Higuchi et al. |
Nov 1976 |
|
Divisions (1)
|
Number |
Date |
Country |
Parent |
6151 |
Jan 1987 |
|