Extrusionsbeschichtete Vliesbahnen

摘要

Nonwoven textile fleeces with a microporous coating of polyolefin with white fracture turbidity are claimed. The fleeces, consisting of polyethylene, polypropylene, polyethylene terephthalate and/or polyamide, are extrusion coated with (co)polyethylene and/or (co)polypropylene containing 10-60 wt.% filler and drawn lengthwise, then crosswise, to produce the turbidity. Nonwoven textile fleeces extrusion-coated on one side with polyolefin are claimed. They have a tensile strength of 4-20 MPa lengthwise and 2-15 MPa crosswise and total mass/unit area of 10-100 g/m<2> and are coated with 5-70, preferably 6-40 g/m<2> polyolefin with a white fracture turbidity of 0.1, preferably 0.1-2%, pore area distribution of NOTLESS 90% in the 0.03-0.20 mu m<2> range and maximum pore area less than 1 mu m. The nonwoven fleece consists of polyethylene, polypropylene, polyethylene terephthalate and/or polyamide and has a mass/unit area of 5-100, preferably 10-40 g/m<2>. The novel features are that (1) the coating comprises (1a) ethylene homopolymer or copolymer of 70-99 wt.% ethylene and 30-1 wt.% 4-18C alpha -olefin, vinyl acetate and/or aliphatic 1-4C alkyl (meth)acrylate with a melt index of 0.1-100 g/10 minutes at 190 degrees C/2.16 kg and/or (1b) propylene homopolymer or copolymer of 70-99 wt.% propylene and 30-1 wt.% ethylene and/or 4-18 C alpha -olefin; (1c) optionally 1-50, preferably 5-30 wt.%, with respect to (b), of modified propylene polymer with melt index 0.1-50, preferably 1-40 g/10 minutes at 230 degrees C/2.16 kg and ratio of 0.20-0.95 for the intrinsic viscosities of the modified and unmodified polypropylene with the same weight average molecular weight; (1d) 10-60 wt.%, with respect to total polyolefins, of (in)organic filler(s) with a maximum particle diameter of 0.1-10, preferably 0.5-5 mu m; and (1e) 0.01-2.5 wt.% stabilizer, 0.01-1 wt.% processing aid and optionally 0.1-1 wt.% antistatic and/or 0.05-1 wt.% nucleating agent, all with respect to total polyolefins; and (2) the coated fleece is produced by (2a) coating the textile with 10-70, preferably 20-40 g/m<2> filled coating mixture, preferably with a residual moisture content less than 600 ppm, by extrusion of the melt at 170-290 degrees C and a rate of 50-300, preferably 150-250 /minutes; and (2b) drawing the coated fleece lengthwise in 1:(1.1-6), preferably 1:(1.1-2) ratio at a temperature 60-0 degrees below the crystallization temperature of the polyolefin coating and then crosswise in 1:(1.1-6), preferably 1:(1.1-2) ratio at a temperature 80-1, preferably 60-2 degrees below the melting temperature of the polyolefin coating, to produce white fracture turbidity, especially by lengthwise drawing.