Abstract: The invention relates to a hollow-fiber membrane for ultrafiltration made from a hydrophobic aromatic sulfone polymer and at least one hydrophilic polymer, the membrane having an open-pore separating layer on the lumen side, an adjoining supporting layer with asymmetric, sponge-like pore structure without finger pores and an outer layer adjoining the supporting layer towards the outer surface. The separating layer has a cutoff between 20 000 and 200 000 daltons, a thickness of max. 10% of the membrane thickness and an essentially isotropic pore structure. The size of the pores in the supporting layer initially increases up to a zone with maximum pore size, and then decreases towards the outer layer, and the outer layer exhibits a thickness of 10 to 30% of the wall thickness and an essentially isotropic pore structure. The mean size of the pores in the outer layer is larger than in the separating layer, but smaller than in the supporting layer.

Abstract: The invention relates to a hollow-fibre membrane for ultrafiltration made from a hydrophobic aromatic sulfone polymer and at least one hydrophilic polymer, the membrane having an open-pore separating layer on the lumen side, an adjoining supporting layer with asymmetric, sponge-like pore structure without finger pores and an outer layer adjoining the supporting layer towards the outer surface. The separating layer has a cutoff between 20 000 and 200 000 daltons, a thickness of max. 10% of the membrane thickness and an essentially isotropic pore structure. The size of the pores in the supporting layer initially increases up to a zone with maximum pore size, and then decreases towards the outer layer, and the outer layer exhibits a thickness of 10 to 30% of the wall thickness and an essentially isotropic pore structure. The mean size of the pores in the outer layer is larger than in the separating layer, but smaller than in the supporting layer.

Abstract: Membranes are based on a homogeneous mixture of polyvinylidene fluoride and a second polymer which can be rendered hydrophilic by chemical reaction. The membranes contain 70 to 98 percent by weight of polyvinylidene fluoride and 2 to 30 percent by weight of a polymer formed essentially from polymethyl and/or polyethyl acrylate, and have a maximum pore size in the range from 0.005 to 10 .mu.m. They can be rendered hydrophilic by means of at least partial hydrolysis, at least partial transesterification with an alcohol which is at least trihydric and contains 3 to 12 carbon atoms, and/or at least partial aminolysis with an amino compound having 2 to 8 carbon atoms. The flat or capillary membranes which have been rendered hydrophilic can contain on their total surface 0.001 to 10 milliequivalents/g of membrane, preferably 0.01 to 5 m equivalents/g of membrane, of --COOH, --OH or --NH.sub.2 groups or corresponding mixtures of these hydrophilic functional groups.

Abstract: A matting agent for plastic compositions comprising either a high molecular weight, gel-containing vinyl chloride polymer with a gel content of 10 to 99% by weight, a maximum mercury porosity of 0.2 cm.sup.3 /g, a maximum plasticizer absorption of 15%, a particle size parameter d' of 10 to 80 .mu.m and a coefficient of uniformity n greater than 3, or a high molecular weight, gel containing copolymer of vinyl chloride and 1 to 40% by weight of comonomer with a gel content of 10 to 99% by weight, a maximum mercury porosity of 0.10 cm.sup.3 /g, a maximum plasticizer absorption of 10%, a particle size parameter d' of 10 to 80 .mu.m and a coefficient of uniformity n greater than 3, plastic articles containing said matting agent and a method of imparting a matt to the surface of plastic articles.

Abstract: A matting agent for plastic compositions comprising either a high molecular weight, gel-containing vinyl chloride polymer with a gel content of 10 to 99% by weight, a maximum mercury porosity of 0.2 cm.sup.3 /g, a maximum plasticizer absorption of 15%, a particle size parameter d' of 10 to 80 .mu.m and a coefficient of uniformity n greater than 3, or a high molecular weight, gel containing copolymer of vinyl chloride and 1 to 40% by weight of comonomer with a gel content of 10 to 99% by weight, a maximum mercury porosity of 0.10 cm.sup.3 /g, a maximum plasticizer absorption of 10%, a particle size parameter d' of 10 to 80 .mu.m and a coefficient of uniformity n greater than 3, plastic articles containing said matting agent and a method of imparting a matt to the surface of plastic articles.