Semipermeable composite membrane

摘要

PCT No. PCT/NL91/00090 Sec. 371 Date Dec. 3, 1992 Sec. 102(e) Date Dec. 3, 1992 PCT Filed Jun. 5, 1991 PCT Pub. No. WO91/18666 PCT Pub. Date Dec. 12, 1991.The invention relates to semipermeable composite membranes having a high sucrose retention and a low salt retention, which membranes are composed of a porous support substrate and a polymer film applied thereon, which polymer film contains an ampholytic polymer. Said ampholytic polymer is entirely or partially made up of repeating units which contain at least one anionic and at least one cationic group. In this way a highly ordered distribution of the anionic and cationic groups over the ampholytic polymer is obtained, which apparently yields the good retention characteristics and reproducibility of the retention characteristics.