Nonwoven fabric for semipermeable membrane support

A nonwoven fabric for semipermeable membrane support, comprising a nonwoven fabric containing organic synthetic fibers as a primary component, with one surface of the nonwoven fabric being a semipermeable membrane-coated side surface having a semipermeable membrane coated thereon, while the other surface being a non-semipermeable membrane-coated surface,

• wherein when a region extending from the semipermeable membrane-coated side surface of the nonwoven fabric to a predetermined portion of the total basis weight in the thickness direction is designated as a coated layer region, a region extending from the non-semipermeable membrane-coated surface of the nonwoven fabric to a predetermined portion of the total basis weight in the thickness direction is designated as a non-coated layer region, and a region obtained by excluding the respective predetermined portions of the total basis weight in the thickness direction from both the semipermeable membrane-coated side surface and the non-semipermeable membrane-coated surface of the nonwoven fabric is designated as a middle layer region, the predetermined portion of the total basis weight is a proportion in the range of 22.5% to 27.5% of the total basis weight of the nonwoven fabric,
• the pressure drop per unit basis weight of the middle layer region after the exclusion is lower than the pressure drop per unit basis weight of the coated layer region and the pressure drop per unit basis weight of the non-coated layer region, and the pressure drop per unit basis weight of the middle layer region after the exclusion is in the range of 10% to 70% relative to the pressure drop per unit basis weight of the nonwoven fabric before the exclusion.