Abstract: Fine grain or fibrous solid active particles are immobilized in an areal or flat, flexible stratified body. The active particles serve for treating a liquid or gaseous medium circulating between the stratified body and the surroundings. The treatment, among other things, encompasses the sorption of substances, if desired, followed by desorption for regenerating the active particles, the emission of substances, the ion exchange and the catalysts of chemical reactions. The active substances or particles are enclosed between a base or substratum layer and a fiber-containing cover layer. Both layers are held together by means of holding fibers which are densely distributed over the entire surface and simultaneously anchored in both layers, whereby at the same time there are also immobilized the active particles. According to a preferred method the holding fibers are removed from the cover layer by fiber-orienting needles.

Abstract: A net formed from partially crystalline synthetic material is made by first forming a plurality of parallel rows of overlapping slits in a solid, biaxially oriented shrinkable sheet of plastic film, such as polypropylene. The sheet is heated to produce a film lattice through shrinkage and thereafter stretched in the longitudinal direction while maintained at a temperature below the crystalline melting point, thereby causing the web portions to be stretched into thin filaments while the intersection portions remain undrawn. The resulting net comprises rhomboid-shaped meshes defined by the filaments and intersections and is expandable in a direction transverse to the net by a multiple of the width of the net.