Composite hollow fiber membrane and hollow fiber membrane module
This composite hollow fiber membrane comprises a gas-permeable non-porous homogeneous layer which has a polyolefin resin (A) as the main component and a porous support layer which is made of a polyolefin resin (B) and which supports said non-porous homogeneous layer, and the composite hollow fiber membrane is characterized in that the polyolefin resin (A) of non-porous homogeneous layer is a block copolymer of ethylene units and at least one type of olefin unit selected from α-olefin units having a carbon number of 3-20. By this means, a gas-permeable composite hollow fiber membrane is provided which has good gas permeability, reduces the impact of condensate on the performance of a gas dissolving module, and has excellent elution properties.
1. A composite hollow fiber membrane comprising: a non-porous homogeneous layer that is gas permeable comprising a polyolefin resin A in an amount of at least 90% by mass; and a porous support layer comprising a polyolefin resin B in an amount of at least 90% by mass that supports the non-porous homogenous layer, wherein the polyolefin resin A of the non-porous homogeneous layer is a block copolymer of ethylene units and at least one type of olefin units selected from C3 to C20 α-olefin units,
wherein the polyolefin resin A of the non-porous homogeneous layer has a melting point of at least 100° C. to no higher than 135° C.
2. The composite hollow fiber membrane according to claim 1 , wherein the α-olefin units of the non-porous homogeneous layer are C6 to C20 α-olefin units.
3. The composite hollow fiber membrane according to claim 2 , wherein the α-olefin units of the non-porous homogeneous layer are 1-octene units.
4. The composite hollow fiber membrane according to claim 1 , wherein oxygen permeability (JISK7126) at 25° C. of the polyolefin resin A of the non-porous homogeneous layer is at least 50×10 −16 mol·m/m 2 ·s·Pa.
5. The composite hollow fiber membrane according to claim 1 , wherein moisture permeance at 25° C. of the polyolefin resin A of the non-porous homogeneous layer is no more than 3.00×10 −3 g/m·24 hr.
6. The composite hollow fiber membrane according to claim 1 , wherein the porous support layer supporting the non-porous homogeneous layer is disposed on an outer-layer side of the non-porous homogeneous layer, and the non-porous homogeneous layer is disposed in a region within 1/10 to ¼ of the membrane thickness from an inner most surface of the hollow fiber membrane in a membrane thickness direction.
7. The composite hollow fiber membrane according to claim 1 , wherein the density of the polyolefin resin A of the non-porous homogeneous layer is 0.86 to 0.89 g/cm 3 .
8. The composite hollow fiber membrane according to claim 1 , wherein the MFRD of the polyolefin resin A of the non-porous homogeneous polyolefin resin A measured in conformance with code D of JIS K7210 is 0.1 to 1.0 g/10 min·190° C.
9. The composite hollow fiber membrane according to claim 1 , wherein the ethylene unit content of said olefin block copolymer of said polyolefin resin A is 25 to 97 mol %.
10. A hollow fiber membrane module comprising the gas-permeable composite hollow fiber membrane according to claim 1 .