Nonwoven fabric for semipermeable membrane support

Abstract

Provided is a nonwoven fabric for semipermeable membrane support, in which adhesiveness of a semipermeable membrane to a support is satisfactory, the thickness uniformity of the semipermeable membrane is satisfactory, and permeation-through of a coating liquid does not occur. Disclosed is a nonwoven fabric for semipermeable membrane support, in which 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 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. The predetermined portion is defined to be about 25%.