Long-fiber nonwoven fabric and filter reinforcement material using the same

1. A long-fiber nonwoven fabric comprising fibers having a birefringence (Δn) of more than or equal to 0.005 and less than or equal to 0.020 and an average fiber diameter of more than or equal to 30 μm and less than or equal to 60 μm, the long-fiber nonwoven fabric having a basis weight amount of more than or equal to 50 g/m 2 and less than or equal to 120 g/m 2 , an average value of Gurley bending resistances in an MD direction and a CD direction according to JIS L1096 (2010) 8.22.1 Method A of more than or equal to 100 mg and less than or equal to 200 mg, and a value of the Gurley bending resistance in the MD direction/the Gurley bending resistance in the CD direction of less than or equal to 3.0,

wherein the fibers constituting the long-fiber nonwoven fabric are single fibers made of a resin containing polyethylene terephthalate serving as a main component and more than or equal to 0.02 mass % and less than or equal to 5 mass % of a thermoplastic polystyrene-based copolymer mixed thereto.

2. The long-fiber nonwoven fabric according to claim 1 , wherein the thermoplastic polystyrene-based copolymer has a glass transition point temperature of 100 to 160° C.

3. A filter reinforcement material using the long-fiber nonwoven fabric according to claim 1 .

4. A pleated filter using the filter reinforcement material according to claim 3 .