Abstract: A microfiltration membrane is made up dissolving m-phenylenediamine-isophthalic acid polymer, a high temperature aromatic polyamide, in one or more solvents selected from the group which consists of N-methylpyrrolidone, dimethylformamide and dimethylacetamide, and the resulting solution in the presence of two or more of these solvents, a structure-loosening agent such as water or a polyhydric alcohol, is cast. After gel formation in the film the latter is washed free from solvents and dried. The microfiltration membrane has high bursting strength and a pore point of 0.05 to 10 microns and a high permeability.

Abstract: Processes for the production of filter elements based on aromatic polyamide in which a semi-finished filter element is produced from a solution of the polyamide in aprotic solvent and the polyamide is then coagulated by immersion in a liquid bath containing precipitating agent may be used for the production of filter elements with a pore size of from 0.05 .mu.m to 10 .mu.

Abstract: A microfiltration membrane is made up dissolving m-phenylenediamine-isophthalic acid copolymer, a high temperature aromatic polyamide, in one or more solvents selected from the group which consists of N-methylpyrrolidone, dimethylformamide and dimethylacetamide, and the resulting solution in the presence of two or more of these solvents, a structure-loosening agent such as water or a polyhydric alcohol, is cast. After gel formation in the film, the latter is washed free from solvents and dried. The microfiltration membrane has high bursting strength and a pore point of 0.05 to 10 microns and a high permeability.