Permselective membrane and use

#This invention relates to a permselective asymetric membrane suitable for hemofiltration comprised of a specific polyamide and to its use in the hemofiltration process and apparatus for carrying out hemofiltration.

#Hemofiltration is a known process for detoxifying blood, i.e. for removing toxic metabolites, even those present in a low concentration, and excess water.

#Metabolites are those components of the living cell, which control the normal course of metabolic reactions, as well as products of metabolism formed or catabolized in human or animal organisms, such as urea, proteins, carbohydrates, and electrolytes, e.g., sodium or potassium salts.

#In the drawings,

#FIG. 1 illustrates schematically an embodiment of the apparatus for carrying out an embodiment of the method according to the present invention wherein the membrane is removed from its support after drying.

#FIG. 2 illustrates schematically an apparatus for carrying out another embodiment of the method according to the present invention wherein the membrane is removed from its revolving support prior to passing through the washing zone.

#Surprisingly it has been found that a permselective membrane comprised of polyamide and having the above-defined composition and properties, exhibits all the properties which are required of a hemofiltration membrane.

#The membrane-forming polymer according to the invention is, particularly, a polycondensate from terephthalic acid and an isomer mixture in the ratio of 1:1 of 2,2,4- and 2,4,4-trimethyl-hexamethylenediamine. This polyamide is, for example, described in "Kunststoffe", 56, 542 (1966) the disclosure of which is hereby incorporated by reference.

#The membrane is asymmetric and self-supporting. Depending on the particulars of the hemofiltration apparatus, the membranes may be in the form of a flat sheet or a tube. For example, in the case that tubular membranes are used these may also be combined with a supporting backing or may comprise a reinforcing fabric, non-woven or net incorporated therein. The membranes in the form of a flat web usually have a thickness of from about 20 preferably about 30 to about 100 microns and exhibit in the wet and in the dry state a high degree of strength, flexibility and flawlessness, at a thickness of 100 microns or less, and even at thickness-values which are as low as 30 microns. The membrane may, however, also be in the form of a self-supporting hollow tube, e.g., a capillary or hollow fiber, preferably having a wall-thickness of from about 20 to about 80 microns.