| abstract |
Mixtures of salts of organic carboxylic acids and organic compounds of non-salt character, dissolved in a C1-C4alkanol, can be concentrated or separated with a semipermeable membrane made from a copolyamide or copolyimide-amide which contains (a) a first aromatic diamine radical and (b) a second aromatic diamine radical which carries -SO3M groups, where M is H(+), a monovalent to polyvalent metal cation or an ammonium cation. Provided the first diamine radical contains C1-C4alkyl groups in the o-positions to the amino groups, the copolymers are radiation-sensitive and can be used for producing protective layers or relief images, development being carded out in an aqueous alkaline medium. |