Filter medium, method for manufacturing same, and filter unit comprising same

A filter medium comprising:

• a first support having a plurality of pores;
• nanofiber webs disposed above and below the first support and comprising nanofibers forming a three-dimensional network structure and a hydrophilic coating layer formed on at least a part of an outer surface of the nanofibers and formed of a hydrophilic coating composition including a hydrophilic polymer compound consisting of polyvinyl alcohol having a degree of polymerization of 1,500 to 1,800 and a degree of saponification of 86 to 89%, a crosslinking agent, and a wettability enhancer, wherein the wettability enhancer is incorporated into the hydrophilic coating layer to improve penetrability of the hydrophilic coating layer into the nanofiber webs;
• and
• second supports interposed between the first support and the nanofiber webs and having a plurality of pores;
• wherein the hydrophilic coating composition comprises 90 to 140 parts by weight of the crosslinking agent with respect to 100 parts by weight of the hydrophilic polymer compound,
• wherein the hydrophilic coating composition comprises 5,000 to 15,000 parts by weight of the wettability enhancer with respect to 100 parts by weight of the hydrophilic polymer compound, and
• wherein the crosslinking agent comprises sulfosuccinic acid and poly(styrene sulfonic acid-maleic acid) at a weight ratio of 1:5 to 1:8.