CPC B01D 69/12 (2013.01) [B01D 69/02 (2013.01); B01D 69/10 (2013.01); B01D 2325/04 (2013.01); B01D 2325/06 (2013.01)] | 6 Claims |
1. A composite semipermeable membrane comprising:
a support membrane; and
a separation functional layer provided on the support membrane, wherein
the separation functional layer comprises a thin membrane,
the thin membrane has a fold structure comprising a plurality of protrusions,
an actual length L of the thin membrane per 1 μm length of the support membrane in a cross-sectional direction perpendicular to a membrane surface is 3.0 μm or more and 100 μm or les,
a thickness of the thin membrane in the protrusion is 15 nm or more and 30 nm or less,
the fold structure comprises a protrusion having a height of 200 nm or more and a protrusion having a height of 10 nm or more and less than 200 nm, and
a ratio (N/M) is 1/20 or more and ½ or less, wherein N is the number of the protrusions having the height of 200 nm or more and M is the number of the protrusions having the height of 10 nm or more.
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