Melt-blown nonwoven fabric and method of manufacturing same

A method of producing a melt-blown nonwoven fabric comprising:

• conveying a web of nonwoven fabric comprising a fiber having an average diameter of 0.1 to 8.0 μm and containing a thermoplastic resin as its main component by sandwiching the web between two sets of belt conveyers each comprising a belt of flexible material having a smooth surface;
• providing a heat treatment zone where a surface of one or both of the two sets of the belt conveyers has been heated to a temperature not lower than cold crystallization temperature of the thermoplastic resin and not higher than the temperature −3° C. lower than melting temperature of the thermoplastic resin in at least a part of a course where the nonwoven fabric is conveyed between the belts;
• and
• heating the nonwoven fabric web in the heat treatment zone by bringing both surfaces of the nonwoven fabric web in contact with the belt conveyers,
• wherein time of contact between the nonwoven web and the belt conveyers in the heat treatment zone is 3 to 600 seconds.