Hollow fiber membrane and manufacturing method therefor
AssigneeToray Industries, Inc.
InventorsKentaro Kobayashi, Kenta Iwai, Yoichiro Kozaki, Satoko Kanamori, Takashi Tachibana
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Abstract
The present invention relates to a hollow fiber membrane in which the thickness L of a spherical structure layer is 60-500 μm (inclusive), the spherical structure layer has a first surface and a second surface, the average diameter Da1 of the spherical structure in a region Sa1 10 μm or less from the first surface and the average diameter db2 of the spherical structure in a region Sb2 10-20 μm from the second surface satisfy the relational expression Da1>db2, and the spherical structure satisfies certain parameters.
Claims19
A hollow fiber membrane comprising a layer of a spherical structure of a resin, wherein
- the layer of the spherical structure has a thickness L of 60 μm or more and 500 μm or less,
- the layer of the spherical structure has a first surface and a second surface, an average diameter Dan of the spherical structure in a region San of 10×(n−1) to 10×n μm from the first surface and an average diameter dbn of the spherical structure in a region Sbn of 10×(n−1) to 10×n μm from the second surface satisfy a relation of Da1>db2, and
- a minimum value imin of a natural number i satisfying the following conditions (1) and (2) satisfies a relation of 3≤imin≤(L−20)/10,
- Da
- 1
- /
- Da
- i
- ≥
- 1.1
- (
- 1
- )
- -
- 0.3
-
- μ
-
- m
- ≤
- Da
- i
- -
- Db
- 2
- ≤
- 0.3
- μ
-
- m
- (
- 2
- )
- provided that n is a natural number, and in the relation of 3≤imin≤(L−20)/10, a decimal point or less of (L−20)/10 is truncated.
A method for manufacturing a hollow fiber membrane, the method comprising:
- (a) a step of dissolving a polyvinylidene fluoride-based resin in a poor solvent to obtain a polyvinylidene fluoride-based resin solution;
- (b) a step of maintaining the polyvinylidene fluoride-based resin solution at a temperature at which primary nucleus formation progresses;
- (c) a step of discharging the polyvinylidene fluoride-based resin solution in a hollow fiber shape through a pipe and a spinneret, and applying a temperature gradient to the polyvinylidene fluoride-based resin solution in a thickness direction thereof in at least one of the pipe or the spinneret, after step (b);
- and
- (d) a step of immersing the polyvinylidene fluoride-based resin solution in a cooling bath, thereby solidifying the polyvinylidene fluoride-based resin solution by solid-liquid type thermally induced phase separation, after step (c), wherein
- a temperature gradient ΔT (° C.) applied in step (c) and a time t (sec) for applying the temperature gradient satisfy a relation of 50≤ΔT×t≤300.
Dependencies are inferred from the claim text.