Hollow fiber membrane and method for producing hollow fiber membrane
A hollow fiber membrane that is a hollow fiber type semipermeable membrane, wherein a Raman value is 70% or more, and the Raman value is a ratio of a minimum value to a maximum value of peak intensities, which are intensities of maximum peaks in each of multiple Raman spectra obtained by Raman spectroscopy at multiple points in a membrane thickness direction of a transverse cross-section of the hollow fiber membrane in a state of being swollen with water.
1. A hollow fiber membrane that is a hollow fiber semipermeable membrane, wherein
a Raman value is 70% or more, and
the Raman value is a ratio of a minimum value to a maximum value of peak intensities obtained by Raman spectroscopy measured at multiple points in a membrane thickness direction of a transverse cross-section of the hollow fiber membrane in a state after being immersed in water.
2. The hollow fiber membrane according to claim 1 , wherein the Raman value is 70% or more and 95% or less.
3. The hollow fiber membrane according to claim 1 , comprising a material that contains at least any of a polymer containing cellulose, a polymer containing polysulfone, and a polymer containing polyamide.
4. The hollow fiber membrane according to claim 1 , wherein an inner diameter of the hollow fiber membrane is 40 μm or more and 200 μm or less.
5. The hollow fiber membrane according to claim 1 , wherein a cross-sectional inner shape of the hollow fiber membrane is a triangular shape.
6. A method for producing a hollow fiber membrane, comprising:
spinning by extruding a membrane-forming solution from a nozzle into a coagulation liquid via an air gap and pulling out a coagulation product of the membrane-forming solution from the coagulation liquid to obtain a hollow fiber membrane that is a hollow fiber semipermeable membrane; and
post-treatment in which the hollow fiber membrane obtained in the spinning is washed with water, and then subjected to at least a hot water treatment and a salt water treatment,
wherein
the membrane-forming solution comprises a solvent and a non-solvent, and a mass ratio of solvent/non-solvent in the membrane-forming solution is 40/60 to 70/30,
the coagulation liquid comprises a solvent and a non-solvent other than water, and the total content of the solvent and the non-solvent other than water in the coagulation liquid is 30 to 70% by mass,
a temperature of the coagulation liquid is 10 to 20° C., and
a temperature of the salt water treatment is 70° C. or more and 95° C. or less.
7. A hollow fiber membrane that is produced by the production method according to claim 6 .