JP2013208544A - Degassing composite hollow yarn membrane and hollow yarn membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a degassing composite hollow yarn membrane excellent in gas permeability, less susceptible to influence due to pressure variation or the like during use and capable of obtaining stable degassing performance, to provide a method for manufacturing the degassing composite hollow yarn membrane, and to provide a hollow yarn membrane module.SOLUTION: In a composite hollow yarn membrane having a nonporous homogenous layer capable of permeating gas and a porous support layer for supporting the homogenous layer, the composite hollow yarn membrane is formed as a concentric cylindrical structure having three or more layers and the homogenous layer is arranged in an area of film thickness of 1/10 to 1/4 from the inside in a film thickness direction. By the degassing composite hollow yarn membrane, excellent gas permeability can be obtained, influence due to pressure variation or the like during operation is less susceptible and stable degassing performance can be obtained.

Description

  The present invention relates to a deaerated composite hollow fiber membrane, a method for producing the same, and a hollow fiber membrane module including the deaerated composite hollow fiber membrane.

The degassing hollow fiber membrane module can be used, for example, for degassing of dissolved gas in an aqueous solution, an inkjet ink mainly composed of an organic solvent, a resist solution manufacturing process, a flow path in a printer, and the like.
A hollow fiber membrane module bundles bundles of hundreds to tens of thousands of hollow fiber membranes, and the hollow fiber membrane bundles are accommodated in, for example, a cylindrical housing case, and an end portion thereof is potted ( Resin). As the adhesive fixing method, since the filling rate of the resin is particularly high, a centrifugal method in which a liquid uncured resin is infiltrated between the hollow fiber membranes using a centrifugal force and then cured is often used. An epoxy resin is used as a potting material in the hollow fiber membrane module from the viewpoint of solvent resistance.

As a method of using such a hollow fiber membrane module, for example, by removing the outside of the hollow fiber membrane while feeding the target liquid into the hollow fiber membrane, the hollow fiber membrane is removed from the voids of the hollow fiber membrane. Examples include a method for removing an object. In this case, the potting material (sealing resin layer) in which the resin as the potting material is cured and the ends of the hollow fiber membrane are bonded and fixed to the pressure in the liquid feeding direction by the liquid feeding of the target liquid, and the outside of the hollow fiber membrane And an attractive force in the pressure reducing direction due to the pressure reduction.
When the hollow fiber membrane comes into contact with the housing case in the vicinity of potting, the potting material may creep up toward the center in the length direction of the hollow fiber membrane between the inner wall of the housing case and the hollow fiber membrane due to capillary action. Since the hollow fiber membrane is adhered to the housing case at the resin creeping-up portion formed by this, the same peeling as that described above may be caused at the time of hardening of the potting material, leading to leakage.

As a countermeasure, it is exemplified that stress associated with curing shrinkage can be relaxed by providing an O-ring as a member for regulating the thickness of the hollow fiber bundle near the end of the hollow fiber bundle of the hollow fiber membrane module ( Patent Document 1).
In the gas permeable membrane, the hollow fiber membrane is obtained by melt-extruding a crystalline thermoplastic resin mainly composed of poly-4-methyl-1-pentene into a hollow fiber shape and then stretching the hollow fiber membrane. Only those having a dense layer with an area open area ratio of 3% or less and a crystallinity of 55% or more and a porous layer inside the film are exemplified (Patent Document 1).

Using a multi-cylindrical spinning nozzle, a crystalline thermoplastic polymer and an amorphous and fusible polymer are arranged in two layers and melt-combined and drawn to form a crystalline polymer. There is exemplified a hollow fiber composite membrane in which only a layer is made porous and is composed of two layers of a porous layer and a non-porous layer (Patent Document 2).
Due to its unique structure, the gas permeable membrane is applied near the potting part (sealing resin layer) with a pressure in the liquid feeding direction due to the feeding of the target liquid and an attractive force in the pressure reducing direction due to the decompression outside the hollow fiber membrane. It can be seen that breakage occurs near the potting portion due to the repeated stress fluctuation.
Since the non-porous layer prevents impregnation of the potting resin, there is a problem that the anchor effect near the potting interface cannot be sufficiently exhibited.

JP 2011-136276 A JP-A-6-210146 Japanese Patent Application Laid-Open No. 7-116483

Since the composite hollow fiber membrane of Patent Document 2 has a non-porous layer on the outer surface of the membrane and has no anchoring effect due to the potting resin, there is a possibility that the composite hollow fiber membrane may be damaged by being affected by pressure fluctuation during operation.
The composite hollow fiber membrane of Patent Document 3 discloses an example in which a non-porous layer is disposed on the inner surface side of the membrane. Although the anchoring effect of potting resin is expected, when an amorphous polymer is placed on the inner layer side during film formation by the melt drawing method, the amorphous polymer is more heat-resistant than the crystalline polymer that forms the porous layer. Since the deformation temperature is low, the film is deformed, and it is difficult to control the film thickness of the non-porous layer, which causes problems such as leakage. Even in the case of the three-layer structure, the location of the gas separation layer has not been sufficiently studied from the detection of the durability of the module.
The present invention is a degassing composite hollow fiber membrane that is excellent in gas permeability, is less affected by pressure fluctuations during operation, and can obtain stable degassing performance, a method for producing the same, and a hollow including the hollow fiber membrane It is an object of the present invention to provide a yarn membrane module.

The present invention has solved the above problems by the following configuration.
A composite hollow fiber membrane having a non-porous homogeneous layer that transmits gas and a porous support layer that supports the homogeneous layer, wherein the composite hollow fiber membrane has a structure of three or more concentric cylinders, and the homogeneous By disposing the layer in the region of 1/10 to 1/4 of the film thickness from the innermost surface in the film thickness direction, it has excellent gas permeability and is not easily affected by pressure fluctuations during operation. Qi performance was able to be obtained.
That is, the present invention provides the following.
[1] A concentric cylindrical composite hollow fiber membrane comprising three or more layers having a gas-permeable non-porous homogeneous layer and a porous support layer supporting the homogeneous layer, wherein the homogeneous layer comprises: A degassed composite hollow fiber membrane, wherein the membrane is disposed in an area of 1/10 to 1/4 of the film thickness from the inside in the film thickness direction.
[2] The degassed composite hollow fiber membrane according to [1], wherein the thickness of the homogeneous layer is 0.5 to 10 μm.
[3] The degassed composite hollow fiber membrane according to [1] or [2], wherein the outer diameter of the hollow fiber membrane is 100 to 2000 μm.
[4] A hollow fiber membrane module comprising the degassed composite hollow fiber membrane according to any one of [1] to [3] above.
[5] The deaerated composite hollow fiber membrane bundle is housed in a housing case, and at least both ends of the deaerated composite hollow fiber membrane bundle are bonded and fixed to the housing case with a potting resin. [4] The hollow fiber membrane module according to [4].

  The module using the deaerated composite hollow fiber membrane of the present invention can sufficiently suppress the stress accompanying the shrinkage of the potting material, thereby suppressing the influence of the membrane breakage due to the pressure fluctuation. Further, the function of the hollow fiber membrane module can be exhibited stably for a long time.

(a) The schematic diagram of the composite hollow fiber membrane of Examples 1 and 2 is shown. (b) A schematic cross-sectional view of the composite hollow fiber membranes of Examples 1 and 2 is shown. The typical sectional view of the hollow fiber membrane of comparative example 1 is shown. The typical sectional view of the hollow fiber membrane of comparative example 2 is shown. The typical sectional view of the hollow fiber membrane of comparative example 3 is shown. The typical sectional view of the hollow fiber membrane of comparative example 4 is shown.

(Degassing composite hollow fiber membrane)
The deaerated composite hollow fiber membrane of the present invention (hereinafter also referred to as “the present composite hollow fiber membrane”) has a non-porous homogeneous layer that allows gas to pass through and a porous support layer that supports the homogeneous layer. It is a composite hollow fiber membrane composed of three or more layers.
Hereinafter, the polymer contained in the homogeneous layer is referred to as “polymer A”, and the polymer contained in the porous support layer is referred to as “polymer B”.

(Homogeneous layer)
The feature of the present invention is that the position of a non-porous homogeneous layer (separation layer) having gas permeability in a concentric cylindrical composite hollow fiber membrane composed of three or more layers is hollowed from the innermost surface of the hollow fiber membrane in the film thickness direction. It is arranged within the range of 1/10 to 1/4 of the yarn film thickness d1. In the present specification, the “position of the homogeneous layer” means a distance from the innermost surface of the hollow fiber to the end surface closest to the innermost surface of the non-porous homogeneous layer (d2 in FIG. 1). The position of the homogeneous layer is in the range of 1/10 to 1/4 in the film thickness direction from the inside of the hollow fiber membrane (from the innermost surface of the hollow fiber to the end surface closest to the innermost surface of the non-porous homogeneous layer) Distance d2): (hollow fiber film thickness d1) is 1;
When processed into a module, the potting resin is impregnated from the outer peripheral direction of the membrane to produce an anchor effect. Since the non-porous homogeneous layer has a non-porous structure, the potting resin will not be impregnated on the inside, and the more the area embedded in the potting resin, the more the membrane will be bent due to pressure fluctuations in the vicinity of the potting part. Can be prevented from being damaged. Further, when the position of the porous support layer inside the non-porous homogeneous layer is set to a region of 1/10 or less of the film thickness, the non-porous homogeneous layer polymer is formed in the stretching step for making the porous support layer polymer porous. This is not preferable because the inner porous support layer polymer is welded to cause defects.
If the area is 1/4 or more, the potting resin embedding area is reduced, and it is not preferable because it is damaged by bending or the like.

  The thickness of the homogeneous layer is preferably 0.5 to 10 μm. If the thickness of the homogeneous layer is 0.5 μm or more, the pressure resistance is improved, and in particular, the region consisting only of the polymer A that forms the homogeneous layer unless the fusion distance with the polymer B that forms the porous layer is greater than the distance. Cannot be ensured, and sufficient gas permeability cannot be obtained. If the thickness of the homogeneous layer is 10 μm or more, the gas separation ability can be satisfied, but the amount of gas permeation decreases, which is not preferable.

The homogeneous layer is a non-porous layer that is permeable to gas.
In the present specification, the term “permeate gas” or “gas permeable” refers to a property of transmitting only gas without transmitting liquid or the like, for example, a film that does not transmit water but transmits water vapor.
In the present specification, “non-porous” means a solid state in which the pores are substantially free of pores having a micrometer order and the inside is clogged with resin.
Such a homogeneous layer is preferably a layer mainly composed of polymer A described later. The layer mainly composed of polymer A is a layer having a content of polymer A of 90% by mass or more. The content of the polymer A in the layer containing the polymer A as a main component is preferably 95% by mass or more, more preferably 99% by mass or more, and particularly preferably 100% by mass.
Examples of the polymer A include polymers obtained mainly from olefin monomers. It may be a polymer obtained using only an olefin monomer, a copolymer of an olefin monomer and another monomer, or a modified resin thereof.
In the olefin block copolymer of the present invention, the ethylene unit content is preferably 25 to 97 mol%, more preferably 40 to 96 mol%, and even more preferably 55 to 95 mol%.
In the olefin block copolymer of the present invention, the melt flow rate (JIS K7210, 190 ° C., 2.16 kg) is preferably 0.1 to 1.0 g / 10 minutes, and preferably 0.3 to 1.0 g / More preferably, it is 10 minutes. This is because a composite hollow fiber membrane excellent in gas permeability and rigidity can be obtained within the above range.
Specific examples thereof include olefin block copolymer (OBC), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), linear very low density polyethylene (VLDPE), reactor TPO, soft polymethylpentene, and the like. Can be mentioned.

In addition, in the homogeneous layer, additives such as an antioxidant, an ultraviolet absorber, a lubricant, an antiblocking agent, a colorant, a flame retardant, etc., if necessary, as long as the purpose of the present invention is not impaired. May be added.
When the present composite hollow fiber membrane has a plurality of homogeneous layers, the thickness of the homogeneous layer is the thickness of each homogeneous layer.

(Porous support layer)
The porous support layer is a porous layer that supports the homogeneous layer.
In this specification, “porous” means that pores having an average diameter of about 0.01 to 1 μm have a porosity of at least 20% by volume.

The porous support layer of the present invention preferably contains polymer B as a main component.
The polymer B is not particularly limited as long as the polymer B can form a porous material such as polyethylene, polypropylene, or polymethylpentene and is compatible with the polymer that forms the homogeneous layer.
In addition, the porous support layer may contain an antioxidant, an ultraviolet absorber, a lubricant, an antiblocking agent, a colorant, a flame retardant, etc., if necessary, as long as the purpose of the present invention is not impaired. An additive may be added.

As for the porosity of a porous support layer, 30-80 volume% is preferable with respect to 100 volume% of the whole porous support layer. When the porosity is 30% by volume or more, excellent gas permeability is easily obtained. When the porosity is 80% by volume or less, mechanical strength such as pressure resistance is improved.
The size of the pores of the porous support layer is not particularly limited as long as sufficient gas permeability and mechanical strength are satisfied.

  Although the thickness of this composite hollow fiber membrane is not specifically limited, It is preferable that the hollow fiber membrane outer diameter is 100-2000 micrometers. If the outer diameter of the hollow fiber membrane is 100 μm or more, a gap between the hollow fiber membranes can be easily obtained at the time of manufacturing the hollow fiber membrane module, and the potting resin can easily enter between the hollow fiber membranes. When the outer diameter of the hollow fiber membrane is 2000 μm or less, the size of the entire module can be reduced even when a hollow fiber membrane module using a large number of hollow fiber membranes is manufactured. As a result, the volume of the potting process portion is also reduced, and it is easy to suppress a decrease in dimensional accuracy due to the shrinkage of the potting resin during the potting process.

The thickness of the porous support layer is preferably 10 to 200 μm. When the thickness of the porous support layer is 10 μm or more, the mechanical strength is improved. If the thickness of the porous support layer is 200 μm or less, the outer diameter of the composite hollow fiber membrane becomes too thick, and it is easy to suppress a decrease in the volumetric efficiency of the membrane when it is incorporated in the membrane module.
When the composite hollow fiber membrane has a plurality of porous support layers, the thickness of the porous support layer is the thickness of each porous support layer.

(Production method of degassed composite hollow fiber membrane)
The composite hollow fiber membrane of the present invention can be obtained by a multilayer composite spinning process and a stretched porous process.
One form of the composite membrane constituting the hollow fiber membrane is a concentric cylindrical three-layer composite membrane structure in which a support layer having gas permeability is sandwiched between porous support layers.

The present composite hollow fiber membrane can be produced, for example, by a method having the following 1) spinning step and 2) stretching step.
1) Spinning step: For example, in the case of the present composite hollow fiber membrane having a three-layer structure, a composite nozzle base in which the outermost layer nozzle portion, the intermediate layer nozzle portion and the innermost layer nozzle portion are arranged concentrically is used. Molten polymer B is supplied to the outermost layer nozzle portion and innermost layer nozzle portion, and molten polymer A is supplied to the intermediate layer nozzle portion. Then, the polymer A and the polymer B are extruded from the respective nozzle portions, and are cooled and solidified in an unstretched state while appropriately adjusting the extrusion speed and the winding speed. Thereby, a hollow fiber membrane precursor having a three-layer structure in which an unstretched homogeneous layer precursor is sandwiched between two unstretched porous support layer precursors in a non-porous state is obtained.

The discharge temperature of the polymer A and the polymer B may be in a state where they can be sufficiently melted and spun.
2) Stretching step: The unstretched hollow fiber membrane precursor obtained by melt spinning is preferably subjected to constant length heat treatment (annealing) at a temperature equal to or lower than the melting point before stretching.
The constant-length heat treatment is performed at 105 to 120 ° C. when the polymer B is polyethylene, 130 to 150 ° C. when the polymer B is polypropylene, 150 to 180 ° C. when the polymethylpentene is used, and the treatment time is 8 to 16 hours. Is preferred.
By performing heat treatment at a predetermined temperature, stability during stretching is improved, and stretching at a high magnification becomes easy. Further, if the treatment time is 8 hours or more, the present hollow fiber membrane having good quality can be easily obtained.

The hollow fiber membrane precursor is stretched under conditions that satisfy the following requirements (i) and (ii).
(I) The relationship between the stretching temperature T (° C.) and the melting point Tm (° C.) of the polymer A is Tm−20 ≦ T ≦ Tm + 40.
(Ii) The stretching temperature T is not higher than the Vicat softening point of the polymer B.
When the stretching temperature T is Tm−20 (° C.) or higher, the porous support layer precursor can be easily made porous, and this composite hollow fiber membrane having excellent gas permeability can be easily obtained. If the stretching temperature T is Tm + 40 (° C.) or less, it is easy to suppress the occurrence of defects such as pinholes due to the disorder of the molecules.
If the stretching temperature T is equal to or lower than the Vicat softening point of the polymer B, the porous support layer precursor can be easily made porous, and the composite hollow fiber membrane having excellent gas permeability can be easily obtained.

In the stretching step, it is preferable to perform cold stretching before stretching (hot stretching) performed at the stretching temperature T. That is, two-stage stretching in which hot stretching is performed subsequent to cold stretching, or multi-stage stretching in which hot stretching is divided into two or more multi-stages subsequent to cold stretching is preferable.
Cold stretching is stretching that causes structural cracking of the film at a relatively low temperature and generates microcracking. The temperature of cold drawing is preferably performed at a relatively low temperature within a range from 0 ° C. to a temperature lower than Tm−20 ° C.
The stretching is preferably slow stretching. If it is low speed drawing, it becomes easy to make it porous while suppressing the yarn diameter from becoming too thin during drawing.

The draw ratio varies depending on the types of the polymer A and the polymer B to be used, but the final ratio (total draw ratio) with respect to the unstretched hollow fiber membrane precursor is preferably 2 to 5 times. When the total draw ratio is 2 times or more, the porosity of the porous support layer is improved, and excellent gas permeability is easily obtained. If the total draw ratio is 5 times or less, the breaking elongation of the composite hollow fiber membrane is improved.
Furthermore, in order to improve the dimensional stability of the hollow fiber membrane obtained by stretching, heat setting is performed in a state where the porous hollow fiber membrane is slightly relaxed under a constant length or within a range of 40% or less. It is preferable.
In order to effectively perform heat setting, the heat setting temperature is preferably not less than the stretching temperature and not more than the melting temperature.

  Since the composite hollow fiber membrane described above has a non-porous homogeneous layer formed of polymer A and a porous support layer formed of polymer B, it has excellent solvent resistance and gas permeability. ing. It also has excellent low elution properties.

(Hollow fiber membrane module)
The hollow fiber membrane module of the present invention is a module comprising the composite hollow fiber membrane described above. The hollow fiber membrane module of the present invention has the same form as a known hollow fiber membrane module except that the present composite hollow fiber membrane is used. For example, a hollow fiber membrane module of a known form in which several hundreds of the present composite hollow fiber membranes are bundled and inserted into a cylindrical housing, and the composite hollow fiber membranes are sealed with a sealing material (potting resin). It is done. Various shapes such as a cylindrical shape, a box shape, and a U-shaped shape are known as the shape of the housing, and these known housings can be used for the hollow fiber membrane module of the present invention.
More specifically, the hollow fiber membrane module has a configuration in which the composite hollow fiber membrane bundle is accommodated in, for example, a cylindrical housing case, and at least both ends thereof are bonded and fixed with a potting material (resin). It is preferable.
Thereby, the potting part makes it possible to isolate | separate the primary side area | region and secondary side area | region which are the inside of a case. As a material for the potting portion, it is preferable to use an epoxy resin from the viewpoint of solvent resistance and water resistance (reduction of swelling). In addition, since the amount of resin increases, the reaction temperature increases, and cracks and separation from the container tend to occur. As the curing agent, aliphatic amines, aromatic amines, organic acid anhydrides and modified amines can be used, and among them, aliphatic polyamines are preferably used.
Further, a reaction retarder may be added in order to suppress the progress of the reaction. As a viscosity of the adhesive agent to be used, it is a viscosity which does not impair the injection property to a sealing part. When the potting resin penetrates into the voids in the film, an anchor effect is exhibited and the adhesive strength is enhanced. Since it is desirable that the degassing hollow fiber membrane module has a high filling rate, a centrifugal method is generally used. In the centrifugal method, the centrifugal force also changes depending on the number of rotations, so that it penetrates into the membrane bundle even when the viscosity is higher than in the stationary method. The specific viscosity is preferably 100 to 2,000 mPa · s. The curing time is preferably within 48 hours, and more preferably within 24 hours from the viewpoint of production efficiency.

It is preferable that the filling rate of the hollow fiber membrane with respect to the potting processed part volume is about 40 to 70% by volume.
The filling rate of the hollow fiber membrane, that is, the filling rate of the hollow fiber membrane defined as the ratio of the outer contour area of the cross section of the hollow fiber membrane to the cross-sectional area of the inner wall of the housing case is in the range of 40 to 70%. Is good. If the filling rate of the hollow fiber membrane is less than 40%, the membrane will be bent in the housing case, and if it exceeds 70%, the membrane will become flat.
In the potting portion, even if the filling rate is in the range of 40 to 70%, it is not preferable that the hollow fiber membrane is biased, and it is preferable to arrange the membrane evenly from the viewpoint of suppressing heat generation.

  As a degassing method using the degassing membrane of the present invention, a raw solution containing dissolved gas is supplied to the inner side (primary side) of the hollow fiber membrane, and the outer side (secondary side) of the hollow fiber membrane is depressurized and dissolved. The dissolved gas can be permeated through the membrane by a driving force proportional to the partial pressure difference of the gas, and the dissolved gas can be discharged to the outside of the hollow fiber membrane. Conversely, the outside of the hollow fiber membrane can be the primary side and the inside of the hollow fiber membrane can be the secondary side. Furthermore, a plurality of hollow fiber membrane modules can be connected in series to deaerate the target chemical solution to a predetermined deaeration level, or a plurality of the hollow fiber membrane modules can be connected in parallel to deaerate a large amount of chemical solution.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
(Measurement of Tm)
Using DSC (manufactured by Seiko Denshi Kogyo), about 5 mg of sample was melted at 200 ° C. for 5 minutes, crystallized by cooling to 40 ° C. at a rate of 10 ° C./min, and further to 200 ° C. at 10 ° C./min. Evaluation was made based on the melting peak temperature and the melting end temperature when the mixture was melted by heating.

(Melt flow rate (MFR))
As for MFR of polyethylene, MFRD (unit: g / 10 minutes) was measured according to JIS K7210 code D (measurement temperature: 190 ° C., load: 2.16 kg).

(density)
The density (unit: kg / m ³ ) was measured according to JIS K7112.

(Porosity)
The porosity (unit: volume%) of the obtained polyethylene composite hollow fiber membrane was measured using a mercury porosimeter 221 type (manufactured by Carlo Elba).

(Gas permeability)
The obtained polyethylene composite hollow fiber membrane was bundled in a U-shape, and the end of the hollow fiber membrane was solidified with urethane resin to produce a hollow fiber membrane module. Oxygen or nitrogen is supplied from the outside of the composite hollow fiber membrane, and the oxygen permeation rate (Q _O2 ) (unit: m / hour · MPa) and nitrogen at 25 ° C. with the inside (hollow part side) of the hollow fiber membrane as normal pressure. The permeation rate (Q _N2 ) (unit: m / hour · MPa) was measured. The membrane area was calculated based on the inner diameter of the hollow fiber membrane. Then, a separation factor (Q _O2 / Q _N2 ) was determined from the measured oxygen transmission rate (Q _O2 ) and nitrogen transmission rate (Q _N2 ).

(Repeated pressure test)
In this test, for each of the hollow fiber membrane modules, one end face side of the potting portion is closed, and the target liquid is supplied to the raw water supply line while being suctioned from the vacuum port, and water pressure is intermittently applied. The presence or absence of occurrence of cracks in the potting portion, the interface between the potting portion and the housing case, and the number of times of water pressure application when a leak occurred due to the crack or separation were measured.
Specifically, after placing the hollow fiber membrane modules obtained in Examples and Comparative Examples in a constant temperature bath at 25 ° C., this was pumped up, and 0.1 [MPa] inside the hollow fiber membrane module. While passing the liquid, the pressure outside the hollow fiber membrane (secondary side) was continuously reduced to −100 kPa, and the liquid feeding was repeated at a cycle of 1 cycle: 10 sec liquid feeding / 10 sec stop.

[Example 1]
As a polymer to be supplied to the innermost layer and the outermost layer (both porous support layers) of the three-layer composite nozzle, high-density polyethylene (trade name Suntech HD B161, MFR 1.35 g / 10 min, density 0.963 g / cm ³ , melting point 130 ° C.) was used. Moreover, as a polymer material supplied to the homogeneous layer (separation layer) of this nozzle, a low density polyethylene (trade name “Harmolex NF324A” manufactured by Nippon Polyethylene Co., Ltd., MFR: 1.0 g / 10 min. Density: 0.906 g / cm ³ , melting point Tm: 120 ° C., Mw / Mn = 3.0).
A composite nozzle base in which the outermost layer nozzle portion, the intermediate layer nozzle portion, and the innermost layer nozzle portion are arranged concentrically was used. The molten polymer B is supplied to the outermost layer nozzle portion and the innermost layer nozzle portion, the molten polymer A is supplied to the intermediate layer nozzle portion, and polymer A / polymer B / polymer A is supplied from the outermost layer to 12/1/2. It discharged so that it might become a discharge ratio. Using these, melt spinning was performed at a discharge port temperature of 200 ° C. and a winding speed of 120 m / min.
This unstretched hollow fiber was annealed at 108 ° C. for 10 hours. Next, the film was stretched by 1.60 times at 23 ± 2 ° C., then stretched by 5.8 times in a heating furnace at 105 ° C., and then subjected to a relaxation process of 0.45 times in a heating furnace at 100 ° C. And finally, it shape | molded so that the total draw ratio might be set to 4 times, and it heat-stretched until the total amount of stretch became 4 times, and obtained the composite hollow fiber membrane. This multilayer composite hollow fiber membrane had a three-layer structure in which a homogeneous membrane (non-porous thin film) was sandwiched between two porous support layers.

As a result of evaluating the membrane performance of the composite hollow fiber membrane thus obtained, the porosity of the entire hollow fiber membrane was 64.5% by volume, the inner diameter was 161 μm, the membrane total thickness was 50 μm, the thickness of the homogeneous layer was 3 μm, the membrane From the outermost layer, the support layer was 40 μm / homogeneous layer 3 μm / support layer 6 μm (position of the homogeneous layer: 6/50 in the hollow fiber film thickness direction from the inside of the hollow fiber membrane).
When the air permeation rate of the three-layer composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) was 0.103 m / hr · Mpa and the nitrogen permeation rate (Q _N2 ) was 0.036 m / hr at room temperature (20 ° C.). -It was Mpa and the separation factor ( _QO2 / _QN2 ) was 2.8.
The hollow fiber membrane module did not leak even after 200000 cycles in the repeated pressure test.

[Example 2]
Example 1 was carried out in the same manner as in Example 1 except that the discharge amount ratio with Example 1 was supplied from the outermost layer so that the ratio of Polymer A / Polymer B / Polymer A was 12/3.
As a result of evaluating the membrane performance of the composite hollow fiber membrane thus obtained, the porosity of the entire hollow fiber membrane was 66.5% by volume, the inner diameter was 163 μm, the membrane total thickness was 48 μm, the thickness of the homogeneous layer was 2 μm, the membrane From the outermost layer, the support layer was 36 μm / homogeneous layer 2 μm / support layer 10 μm (position of the homogeneous layer: 10/48 in the hollow fiber film thickness direction from the inside of the hollow fiber membrane).
When the air permeation rate of the three-layer composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) was 0.110 m / hr · Mpa and the nitrogen permeation rate (Q _N2 ) was 0.039 m / hr at room temperature (20 ° C.). -It was Mpa and the separation factor ( _QO2 / _QN2 ) was 2.8.
The hollow fiber membrane module did not leak even after 200000 cycles in the repeated pressure test.

[Comparative Example 1]
Example 1 was carried out in the same manner as in Example 1 except that the discharge amount ratio and that of Example 1 were supplied from the outermost layer such that Polymer A / Polymer B / Polymer A were 6/6.
As a result of evaluating the membrane performance of the composite hollow fiber membrane thus obtained, the porosity of the whole hollow fiber membrane was 66 volume%, the inner diameter was 160 μm, the membrane total thickness was 48 μm, the thickness of the homogeneous layer was 2 μm, and the membrane outermost layer. To support layer 24 μm / homogeneous layer 2 μm / support layer 22 μm (position of homogeneous layer: 22/48 in the hollow fiber film thickness direction from the inside of the hollow fiber membrane).
When the air permeation rate of the three-layer composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) was 0.10 m / hr · Mpa and the nitrogen permeation rate (Q _N2 ) was 0.035 m / hr at room temperature (20 ° C.). -It was Mpa and the separation factor ( _QO2 / _QN2 ) was 2.8.
The hollow fiber membrane module leaked at 140000 cycles in the repeated pressure test.

[Comparative Example 2]
Example 1 was carried out in the same manner as in Example 1 except that the discharge amount ratio and that in Example 1 were supplied from the outermost layer so as to be 2/1/12 of Polymer A / Polymer B / Polymer A.
As a result of evaluating the membrane performance of the composite hollow fiber membrane thus obtained, the porosity of the entire hollow fiber membrane was 65% by volume, the inner diameter was 161 μm, the total membrane thickness was 49 μm, the homogeneous layer thickness was 2 μm, the outermost membrane layer. To support layer 6 μm / homogeneous layer 2 μm / support layer 41 μm (position of homogeneous layer: 41/49 in the hollow fiber film thickness direction from the inside of the hollow fiber membrane).
When the air permeation rate of the three-layer composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) was 0.10 m / hr · Mpa and the nitrogen permeation rate (Q _N2 ) was 0.035 m / hr at room temperature (20 ° C.). -It was Mpa and the separation factor ( _QO2 / _QN2 ) was 2.8.
The hollow fiber membrane module leaked in the cycle 80000 times in the repeated pressure test.

[Comparative Example 3]
Using a two-layer nozzle, the same combination of Example 1 and polymer is used so that a homogeneous layer is arranged in the outermost layer, and the discharge ratio is supplied from the outermost layer to 1/14 of polymer B / polymer A. The others were carried out in the same manner as in Example 1.
As a result of evaluating the membrane performance of the composite hollow fiber membrane thus obtained, the porosity of the entire hollow fiber membrane was 66% by volume, the inner diameter was 159 μm, the membrane total thickness was 50 μm, the thickness of the homogeneous layer was 2 μm, and the membrane outermost layer. To homogeneous layer 2 μm // support layer 48 μm (homogeneous layer position: 48/50 in the hollow fiber film thickness direction from the inside of the hollow fiber membrane).
When the air permeation rate of the three-layer composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) was 0.18 m / hr · Mpa and the nitrogen permeation rate (Q _N2 ) was 0.09 m / hr at room temperature (20 ° C.). -It was Mpa and the separation factor ( _QO2 / _QN2 ) was 2.0.
Since the homogeneous layer was brought to the outermost layer, the original separation factor of the homogeneous layer polymer could not be maintained due to scratches in the stretching process.

[Comparative Example 4]
Using a two-layer nozzle, the combination of Example 1 and the polymer is the same so that a homogeneous layer is arranged in the innermost layer, and the discharge rate ratio in Example 1 is 12/1 from the outermost layer to Polymer A / Polymer B. The procedure was the same as in Example 1 except that the product was supplied.
As a result of evaluating the membrane performance of the composite hollow fiber membrane thus obtained, the porosity of the entire hollow fiber membrane was 66% by volume, the inner diameter was 160 μm, the total membrane thickness was 49 μm, the homogeneous layer thickness was 2 μm, and the membrane outermost layer. To support layer 47 μm / homogeneous layer 2 μm (homogeneous layer position: 2/49 in the hollow fiber film thickness direction from the inside of the hollow fiber membrane).
When the air permeation rate of the three-layer composite hollow fiber membrane was measured, the oxygen permeation rate (Q _O2 ) was 0.20 m / hr · Mpa and the nitrogen permeation rate (Q _N2 ) was 0.18 m / hr at room temperature (20 ° C.). -It was Mpa, and the separation factor (Q _O2 / Q _N2 ) was 1.2. By bringing the homogeneous layer into the inner layer, an irreversible change was made up to the inner layer, resulting in porosity, which resulted in defects in the homogeneous layer.

  The composite hollow fiber membrane of the present invention is very useful for the production of functional water used in semiconductor cleaning liquids and the degassing of dissolved gases in ink for inkjet printers.

1: Porous support layer (inner layer)
2: Non-porous homogeneous layer 3: Porous support layer (outer layer)
d1: Hollow fiber film thickness d2: Distance from the innermost surface of the hollow fiber membrane to the non-porous homogeneous layer

Claims (5)

  A concentric cylindrical composite hollow fiber membrane comprising three or more layers having a gas-permeable non-porous homogeneous layer and a porous support layer for supporting the homogeneous layer, wherein the homogeneous layer is a membrane from the innermost surface. A deaerated composite hollow fiber membrane, which is disposed in a region of 1/10 to 1/4 in the thickness direction.   The deaerated composite hollow fiber membrane according to claim 1, wherein the thickness of the non-porous homogeneous layer is 0.5 to 10 µm.   The degassed composite hollow fiber membrane according to claim 1 or 2, wherein the hollow fiber membrane has an outer diameter of 100 to 2000 µm.   The hollow fiber membrane module which comprises the deaeration composite hollow fiber membrane as described in any one of Claims 1-3.   The deaerated composite hollow fiber membrane bundle is housed in a housing case, and at least both ends of the deaerated composite hollow fiber membrane bundle are bonded and fixed to the housing case with a potting resin. Hollow fiber membrane module.

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