Patent ID: 8207073

Claim:
A highly water pressure-resistant polyester nonwoven fabric composed of a laminated nonwoven fabric structure, the structure comprising an extremely fine fiber nonwoven fabric layer formed out of extremely fine fibers formed by melt blowing an extruded mixture of a polyester resin and from 10 to 50% by weight of a polyolefin resin based on the weight of the mixture, said fibers having a fiber diameter of 5 μm or less, and a filamentary fiber nonwoven fabric layer composed of a polyester resin containing 7% by weight or less of a polyolefin resin and having a fiber diameter of 7 μm or more, said layers being integrated together by thermocompressive bonding to form the laminated structure, wherein the extremely fine fibers forming the extremely fine fiber nonwoven fabric are formed out of a polyester resin having a solution viscosity from 0.2 to 0.8 η sp /C, the polyolefin resin mixed with the polyester resin forming the extremely fine fibers has a MFR (melt flow rate), which is determined under a temperature of 230° C. and a load of 21.18 N in accordance with JIS K 7210, of 500 to 3,000 g/10 min, a discontinuous phase of the polyolefin resin is scattered on a surface and in a longitudinally aligned direction of the extremely fine fibers, the extremely fine fibers do not have a sheath-core structure, and the laminated structure has a water pressure resistance of 5.2 kPa or more.