Abstract: A heat-resistant separator composed of a non-woven fabric of high-melting resin, 1 to 20 &mgr;m in average fiber diameter, 5 to 300 g/m2 in basis weight, 1 to 200 cc/cm2/sec in air permeability, and 0.01 to 1.0 mm in thickness, or a laminated heat-resistant separator composed of a laminate having a melt-blown, non-woven fabric layer of high-melting resin, 1 to 20 &mgr;m in average fiber diameter, 5 to 300 g/m2 in basis weight, 1 to 200 cc/cm2/sec in air permeability, and 0.01 to 1.0 mm in thickness is more resistant to heat, and hence safer, and is suitable for batteries and electrical double-layer capacitors serviceable at high temperature.

Abstract: The nozzle piece of the present invention is provided with circular cross sectional nozzles having different sizes disposed in a row in front of the die, with n-numbered smaller nozzles B (hole diameter: Db) between adjacent larger nozzles A (hole diameter: Da). It gives melt-blown non-woven fabric of monolithic structure in one step, composed of fine fibers having a diameter in a range from 1 to 10 &mgr;m diameter Variance ratio F of 2.0 or more and wide fiber diameter distribution.