WET-LAID NONWOVEN FABRIC FOR SEMIPERMEABLE MEMBRANE SUPPORTING BODY, METHOD FOR PRODUCING SAID WET-LAID NONWOVEN FABRIC, AND METHOD FOR IDENTIFYING LOW-DENSITY DEFECT OF WET-LAID NONWOVEN FABRIC

摘要

Provided is a uniform semipermeable membrane supporting body which does not cause any defect in the semipermeable membrane coating layer when a semipermeable membrane coating liquid is applied, and is free of low density defects. The wet-laid nonwoven fabric for a semipermeable membrane supporting body according to the present invention contains a synthetic fiber as a main constituent fiber, has been subjected to hot press processing, has a pressure loss at a face velocity of 5.2 cm/second of from 50 Pa to 3000 Pa and a sheet density of 0.5 g/cm 3 or greater, and satisfies the evaluation criterion of condition 1 or condition 2: (Condition 1) Spots are not observed when solid printing is carried out with a printing ink over the entire surface of one surface of the wet-laid nonwoven fabric for a semipermeable membrane supporting body (rolled product, cut to a length of 1800 mm in the length direction); and (Condition 2) When a wet-laid nonwoven fabric for a semipermeable membrane supporting body that has been cut to a size of 210 mm x 297 mm is subjected to solid printing over the entire surface of one surface with a printing ink, is used as a sample, spots are not observed in 95% or more of the samples among such samples thus extracted.