US Patent 7255763 Process for making fibrous web having inelastic extensibility

Component thermoplastic synthetic fiber having inelastic extensibility as well as fiber diameter of 5-20 μm constituting a fibrous web is obtained by melt spinning a mixture of two or more thermoplastic synthetic resins each having a number-average molecular weight in a range of 20000-150000 at a draft ratio of 200-2300. In the case of the mixture consisting of at least two types of thermoplastic synthetic resin Ra, Rb having number-average molecular weights Ma, Mb, respectively, wherein a ratio Ma/Mb is 1.1 or higher, Ra is of 20-80 wt %, Rb is of 80-20 wt % and a sum of Ra and Rb makes up 50-100 wt % of the mixture.