Composite membrane for separating out water and method for its production

摘要

Composite membrane comprises at least one separation layer (4) characterized in having been pre-crosslinked with polyvinyl alcohol and separately post-crosslinked with one of an acid and an acid-releasing compound and at least one dialdehyde. Independent claims are included for: making the composite membrane comprising: applying a porous support layer (3) onto a carrier layer (2) of porous material, applying an aqueous starting solution containing polyvinyl alcohol to the support layer, cross-linking the polyvinyl alcohol to the support layer to form a separation layer of pre-crosslinked polyvinyl alcohol on it, applying one of an acid and an acid-releasing compound and at least one dialdehyde to the separation layer and crosslinking the polyvinyl in the separation layer with the dialdehyde to form a separation layer of post-crosslinked polyvinyl alcohol on the support layer; or applying a starting solution containing polyvinyl alcohol to a support layer, pre-crosslinking of the polyvinyl alcohol, applying a solution for the post-crosslinking of the polyvinyl alcohol, in which the solution containing one of an acid and an acid-releasing compound as well as at least one dialdehyde and post-crosslinking of the separation layer.