Hollow porous membrane
View Patent ↗A hollow porous membrane of the present invention comprises a plurality of porous membrane layers, at least two layers of which are formed using a thermoplastic resin (a) having a mass average molecular weight of 500,000 or more, and the hollow porous membrane having a bursting pressure of 200 kPa or more when an internal pressure is applied and exhibiting virus removal performance of LRV 4 or more in the case of using MS2 phage as a test bacterium.
1. A hollow porous membrane, comprising:
a plurality of porous membrane layers,
wherein
a mass average molecular weight of a thermoplastic resin (a) used in an outermost layer of the layers formed using thermoplastic resins (a) is greater than a mass average molecular weight of a thermoplastic resin (a) used in each of the other layers,
at least two layers of the plurality of porous membrane layers are formed using a thermoplastic resin (a) having a mass average molecular weight of 500,000 or more, and
the hollow porous membrane has a bursting pressure of 200 kPa or more when an internal pressure is applied and exhibiting virus removal performance of LRV 4 or more in the case of using MS2 phage as a test bacterium.
2. The hollow porous membrane according to claim 1 , wherein the thermoplastic resin (a) is polyvinylidene fluoride.
3. The hollow porous membrane according to claim 1 , further comprising:
a tubular support which comprises a multifilament,
wherein the plurality of porous membrane layers are laminated on an outer circumferential surface of the support.
4. The hollow porous membrane according to claim 3 , wherein the support is a braid support formed by circular knitting into a cylindrical shape.
5. The hollow porous membrane according to claim 3 , wherein the multifilament is polyester.
6. The hollow porous membrane according to claim 3 , wherein the multifilament has a fineness of from 50 to 1000 dtex.
7. The hollow porous membrane according to claim 3 , wherein the support is a heat treated support.
8. The hollow porous membrane according to claim 1 , wherein at least one layer of the layers formed using the thermoplastic resin (a) is formed using a mixture of plural kinds of thermoplastic resins having different molecular weights.
9. The hollow porous membrane according to claim 8 , wherein all of the plural kinds of thermoplastic resins have a mass average molecular weight of 400,000 or more.
10. The hollow porous membrane according to claim 1 , wherein an outer diameter is from 1.0 to 5.0 mm.
11. The hollow porous membrane according to claim 1 , wherein a mass average molecular weight of a thermoplastic resin (a) used in an outermost layer of the layers formed using thermoplastic resins (a) is 600,000 or more.
12. The hollow porous membrane according to claim 1 , wherein a total thickness of the plurality of porous membrane layers is 50 μm or more and 200 μm or less.
13. The hollow porous membrane according to claim 1 , wherein a water permeability is 8 m 3 /m 2 /hr/MPa or more.
14. The hollow porous membrane according to claim 1 , wherein an inner diameter is 0.6 mm or more.
15. The hollow porous membrane according to claim 1 , wherein all of the porous membrane layers are formed of a thermoplastic resin (a) having a mass average molecular weight of 500,000 or more.