JPH07313854A - Production of porous hollow yarn membrane - Google Patents

Abstract

PURPOSE:To obtain a porous hollow yarn membrane which has sufficient gas exchangeability and is free from plasma leakage is spite of long-term use by melting a kneaded mixture composed of polypropylene(PP), org. filter and crystal nucleus forming agent, discharging the melt to a hollow shape and solidifying the melt with a cooling and solidifying liquid, then bringing the hollow material into contact with an extracting liquid. CONSTITUTION:A compd. 11 for spinning prepd. by compounding the PP, the org. filler, such as liquid paraffin, for uniformly dispersing the Pp into a melt state and the crystal nucleus forming agent is supplied to a hopper 12. The compd. is melted and kneaded by a single screw extruder 13 and is then extruded. The extrudate is sent to a spinning device 14, where the extrudate is discharged from the annular spinning hole of a spinneret device 15 into a gaseous atmosphere. This discharged hollow material 16 is dropped at a prescribed distance and is reduced down to a desired outside diameter and is then allowed to flow down in the cooling and solidifying liquid 17 consisting of a polyethylene glycol and water. Further, the solidified hollow material 16 is brought into contact with the extracting liquid 25 which dissolves the org. filler and the polyethylene glycol and does not dissolve the PP, by which the hollow matter is extracted away.

Description

Detailed Description of the Invention

[0001]

[Industrial applications]

The present invention relates to a method for producing a porous hollow fiber membrane. More specifically, the present invention relates to a method for producing a porous hollow fiber membrane which has a sufficient gas exchange capacity and does not leak plasma during long-term use.

[Prior art]

Generally, in the case of cardiac surgery, etc., in order to add oxygen and remove carbon dioxide from blood that is circulated extracorporeally,
A hollow fiber membrane oxygenator is used. There are two types of hollow fiber membranes used in such artificial lungs, homogeneous membranes and porous membranes. In a homogeneous film, molecules of a passing gas are dissolved in the film and diffused to move the gas. Further, in the porous membrane, the fine pores of the membrane are significantly larger than the gas molecules to be permeated, so that the gas passes through the pores as a volume flow. Various artificial lungs using such a porous material are used.

As a method for producing such a porous material, for example, polypropylene is used by using a nozzle for producing a hollow fiber,
Spinning temperature 210-270 ° C, draft ratio 180-600
Melt spinning, and then first-stage heat treatment at 155 ° C. or lower, followed by 30 to 200% stretching at less than 110 ° C., and then second-stage heat treatment at a first stage heat treatment temperature or higher and 155 ° C. or lower. is there. (Japanese Patent Publication Sho 56-52,123
issue). However, the porous hollow fiber thus obtained physically forms pores by stretching the polypropylene hollow fiber, so the pores are linear pores that are substantially horizontal in the film thickness direction, and Since the hollow fiber is formed by a crack generated in the axial direction of the hollow fiber, the cross section is slit-shaped. Further, the pores penetrate substantially linearly and have a high porosity. Therefore, the porous hollow fiber has a high water vapor permeability, and when blood is circulated extracorporeally for a long period of time, plasma leaks out.

[0005]

The object of the present invention is to produce a polypropylene porous hollow fiber membrane which has a sufficient gas exchange capacity and is free from plasma leakage during long-term use and suitable for artificial lungs. It provides a method.

[0006]

[Means for Solving the Problems] What achieves the above object is to melt a kneaded product obtained by kneading polypropylene, an organic filler which is uniformly dispersed in polypropylene under melting of the polypropylene, and a crystal nucleating agent. In this state, the hollow kneaded product was discharged in a hollow form from the annular spinning hole, the hollow kneaded product was cooled and solidified by contact with a cooling and solidifying liquid consisting of a mixture of polyethylene glycol and water, and then cooled and solidified,
It is a method for producing a porous hollow fiber membrane in which the polypropylene is not dissolved and the organic filler is extracted and removed by contacting it with an extract that dissolves the organic filler.

The cooling solidification liquid has a mixing ratio of polyethylene glycol and water of polyethylene glycol:
Water = 75-50: 25-50 is preferable.

The method for producing the porous hollow fiber membrane of the present invention will be described below with reference to examples. In the method for producing a porous hollow fiber membrane of this example, a kneaded product obtained by kneading polypropylene, an organic filler that is uniformly dispersed in polypropylene under melting of the polypropylene, and a crystal nucleating agent is melted. A discharging step of discharging the hollow kneaded material into a hollow shape from the annular spinning hole, a cooling and solidifying step of bringing the discharged hollow kneaded material into contact with a cooling and solidifying liquid composed of a mixture of polyethylene glycol and water to solidify by cooling, and a cooling and solidifying hollow Removal step of removing the organic filler and polyethylene glycol from the kneaded mixture, a heat treatment step of heat treating the hollow fiber membrane from which the organic filler has been removed, and a winding step of winding the heat treated hollow fiber membrane. ing.

In the manufacturing method of this embodiment, first, polypropylene, an organic filler which is uniformly dispersed in polypropylene under melting of polypropylene, and a crystal nucleating agent are melt-kneaded to obtain a substantially uniform mixture. A compound for spinning (kneaded product for spinning) in which an organic filler and a crystal nucleating agent are dispersed is prepared. The polypropylene is not limited to propylene homopolymer, but may be a block polymer with other monomer containing propylene as a main component, but those having a melt index (M.I.) of 5 to 70 are preferable, and M.I. I. Is preferably 10 to 40. Among the polypropylenes, propylene homopolymer is particularly preferable, and among them, those having high crystallinity are most preferable.

As the organic filler, it is necessary to disperse the polypropylene substantially uniformly in the polypropylene under melting and to be easily soluble in the extract described later. Examples of such a filler include liquid paraffin (number average molecular weight 100 to 2000), α-olefin oligomer [eg ethylene oligomer (number average molecular weight 100 to 2000).
2000), propylene oligomer (number average molecular weight 10
0-2000), ethylene-propylene oligomer (number average molecular weight 100-2000) and the like], paraffin wax (number average molecular weight 200-2500), various hydrocarbons and the like, and liquid paraffin is preferable.

The blending ratio of polypropylene and organic filler is 35 to 250 parts by weight, preferably 80 to 220 parts by weight, based on 100 parts by weight of polypropylene. That is, when the amount of the organic filler is less than 35 parts by weight, a part of the obtained hollow fiber membrane is composed of a continuous phase of polypropylene and it becomes impossible to exhibit sufficient gas permeability, while when it exceeds 250 parts by weight, the viscosity is increased. Is too low and the processability of forming into a hollow shape is deteriorated.

In the present invention, the crystal nucleating agent blended in the raw material has a melting point of 150 ° C. or higher (preferably 20).
It is an organic heat-resistant substance having a gelling point of 0 to 250 ° C.) and a temperature not lower than the crystallization initiation temperature of the polyolefin used. The reason for incorporating such a crystal nucleating agent is to reduce the size of polypropylene particles, thereby narrowing the voids between particles, that is, communicating pores, and increasing the pore density. For example, 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-bis (p-methylbenzylidene) sorbitol, 1,3,2,4 bis (p-ethylenebenzylidene) Sorbitol, sodium bis (4-t-butylphenyl) phosphate, sodium benzoate, adipic acid, talc, kaolin and the like are listed as crystal nucleating agents. As a crystal nucleating agent, benzylidene sorbitol, particularly 1,3,2,4-bis (p-ethylbenzylidene) sorbitol, 1,3,2,4 bis (p-methylbenzylidene) sorbitol, is dissolved in blood. Less preferred. The compounding ratio of the polypropylene and the crystal nucleating agent is 0.1 to 5 parts by weight, preferably 0.2 to 1.0 part by weight, based on 100 parts by weight of polypropylene.

Each raw material mixture is added to an extruder such as a twin-screw extruder at a predetermined ratio, melt-kneaded, extruded, and then pelletized to form a spinning raw material mixture. . It should be noted that, without using such pelletized spinning raw material kneaded material, a predetermined amount of polypropylene, an organic filler, and a crystal nucleating agent are put into a hopper 12 shown in FIG. 1 described later, and the kneader is communicated with the hopper. Alternatively, a kneaded product may be used.

A spinning compound 11 in which polypropylene, an organic filler and a crystal nucleating agent are compounded is put in from a hopper 12 and has a single-screw extruder 13 having a kneading function.
To the spinning device 14 after being melt-kneaded and extruded by feeding the mixture to the spinning device 14 and an annular spinning hole of the spinneret device 15 (not shown).
To a gaseous atmosphere, for example air. Specifically, the raw material mixture (kneaded product for spinning) is, for example, 160 to 250 ° C., preferably 1 using an extruder such as a single screw extruder.
It is melted and kneaded at a temperature of 80 to 220 ° C., and if necessary, it is discharged into the gas atmosphere from the annular hole of the spinning device using a gear pump having a high quantitative property to form a hollow material. It should be noted that an inert gas such as nitrogen, carbon gas, helium, argon, or air is self-primed or forcedly introduced into the center of the inside of the annular hole.

Then, the discharged hollow material 16 is dropped in the air for a predetermined distance to reduce its diameter to a desired outer diameter, and then the hollow material 16 is introduced into a cooling tank 18 containing a cooling and solidifying liquid 17. By contacting with the cooling and solidifying liquid 17, it is cooled and solidified. The fall distance of the hollow material (the distance from the annular spinning hole of the spinneret device 15 to the liquid surface of the cooling and solidifying liquid 17) is 5 to 10.
00 mm is preferable, and 10 to 500 mm is particularly preferable. This is because if the falling distance is less than 5 mm, pulsation may occur and the hollow solid material may be crushed when it rushes into the cooled solidified liquid.

In this case, the hollow material 16 and the cooling solidification liquid 17
As shown in FIG. 1, the contact with the cooling solidification liquid 17 is made to flow down into a cooling solidification liquid flow pipe 19 which is provided through the bottom of the cooling tank 18 and is directed downward, and the cooling solidification liquid 17 is hollowed along the flow. It is desirable to bring the particles 16 into parallel flow contact. The hollow material is not yet sufficiently solidified in the cooling tank, and since the central portion is a gas, it is easily deformed by an external force. Therefore, as shown in FIG. The solidified liquid 17 is caused to flow down into a cooling solidified liquid flow pipe 19 provided downward, and the hollow material is forcibly moved by bringing the hollow material into parallel flow contact along the flow,
Moreover, it is possible to prevent deformation of the hollow object due to external force (fluid pressure, etc.). At this time, the flow rate of the cooled solidified liquid is sufficient under the natural flow.

The cooled and solidified liquid 17 is received and stored in the solidifying tank 20, the hollow material 16 is introduced therein, and it is deflected by a deflecting rod 21 to be sufficiently brought into contact with the cooled and solidified liquid 17 to be solidified. Let The accumulated cooling solidified liquid 17 is discharged from the circulation line 23, and the circulation pump 24 is used to cool the cooling tank 18.
Circulate to.

In the present invention, the cooling and solidifying liquid used is a mixture of polyethylene glycol and water. The mixture of polyethylene glycol and water does not dissolve the polypropylene, the crystal nucleating agent, or the organic filler. Further, the specific heat capacity is lower than that of water alone. The specific heat capacity is 0.72
About 0.9 is preferable. In addition, the mixing ratio of polyethylene glycol and water is polyethylene glycol: water = 7.
It is preferably 5 to 25:25 to 75. The polyethylene glycol has an average molecular weight of 100 to
The thing of 400 is preferable and the thing of 150-300 is especially preferable.

As described above, the cooling and solidifying liquid used in the present invention has a specific heat capacity near the middle of water and polyethylene glycol, so that the cooling effect is high. Therefore, the outer surface of the hollow kneaded product that has come into contact with the cooling solidification liquid is solidified in a state where the formation of polypropylene fine particles on the outer surface does not proceed so much. Therefore, on the surface of the solidified hollow material, the organic filler in a finely dispersed state is present, and the pores formed by the removal of the organic filler later become extremely fine, and The outer surface becomes a smooth so-called skin layer. Further, since the pores formed on the outer surface are fine, the leakage of plasma is extremely small even when used in an artificial lung. The temperature of the cooled and solidified liquid is 10 to 90 ° C, preferably 20 to 75 ° C. Particularly preferably, 20
~ 45 ° C.

Next, the solidified hollow material 16 is guided to a shower / conveyor type extractor 27 which sprinkles an extract 25 which dissolves the organic filler and polyethylene glycol but does not dissolve polypropylene in a shower shape. In this extractor 27, the hollow material 16 is the belt conveyor 2
While being transported over 6, the organic filler and polyethylene glycol are extracted and removed by being sufficiently contacted with the extract.
The hollow material drawn out from the extractor 27 by the drive roll 22 is further wound up after being subjected to steps such as re-extraction and dry heat treatment, if necessary.

The method for dissolving and extracting the organic filler and the polyethylene glycol is not limited to the shower system in which the shower of the extraction liquid is dropped on the hollow material on the belt conveyor as shown in FIG. Any method may be used as long as the hollow material can come into contact with the extraction liquid, such as a tank method, a rewinding method in which the hollow material once wound is rewound into another skein, and the sac is immersed in the extraction liquid. It is also possible to combine two or more of these methods.

Any extract can be used as long as it does not dissolve the polypropylene constituting the hollow fiber membrane and can dissolve and extract the organic filler and polyethylene glycol. As an example, for example, methanol, ethanol, propanols, butanols, pentanols, hexanols, octanols, alcohols such as lauryl alcohol, 1,1,2-trichloro-1,
There are halogenated hydrocarbons such as 2,2-trifluoroethane, trichlorofluoromethane, dichlorofluoromethane, 1,1,2,2-tetrachloro-1,2-difluoroethane, etc., and among these, extraction capacity for organic fillers From the viewpoint of the above, halogenated hydrocarbons are preferable, and chlorofluorohydrocarbons are particularly preferable from the viewpoint of safety to the human body.

The hollow fiber membrane thus obtained is further heat-treated if necessary. The heat treatment is performed at a temperature of 50 to 160 ° C., preferably 70 to 120 ° C. for 5 seconds to 120 minutes, preferably 10 seconds to 60 minutes in a gaseous atmosphere of air, nitrogen, carbon dioxide gas, or the like. This heat treatment stabilizes the structure of the hollow fiber membrane and increases the dimensional stability. Further, stretching may be performed before or during the heat treatment. Such heat treatment is performed by passing the hollow fiber membrane, which is solidified and the organic filler is extracted, through the heat treatment apparatus 30. The heat treatment device 30 has a heater 28 for heating the inside and a plurality of rollers 29 that meander to pass the hollow fiber membrane. The hollow fiber membrane thus heat-treated is sent out by the drive roll 22 and wound on the bobbin 32 mounted in the winder 31. The hollow fiber membrane thus obtained is most suitable for use in a hollow fiber membrane type artificial lung.

The gas permeability of the hollow fiber membrane obtained by the conventional stretching method was unnecessarily high for use as an artificial lung. That is, when blood is circulated inside the hollow fiber, the oxygen addition ability has a large membrane resistance on the blood side, the resistance of the hollow fiber membrane is not rate-determining, while the carbon dioxide gas removal ability depends on the hollow fiber membrane resistance. However, its permeability was excessive, and when blood was circulated outside the hollow fiber, the gas exchange capability was also dependent on the resistance of the hollow fiber membrane, but its permeability was excessive. However, the gas permeability of the hollow fiber membrane of the present invention as a single membrane is lower than that of the conventional stretching method, but sufficient performance can be obtained for use by incorporating it into an artificial lung, and further, by the extraction method. Because of this, there is no leakage of blood due to pinholes, and therefore it is possible to prevent a decrease in gas exchange capacity.

The polypropylene porous hollow fiber membrane thus produced has an inner diameter of 150 to 300 μm.
m, preferably 180 to 250 μm, and a wall thickness of 10 to 15
It is a substantially circular polypropylene hollow fiber membrane having a diameter of 0 μm, preferably 20 to 100 μm, and more preferably 40 to 50 μm. Further, the porosity is 10 to 60%, more preferably 30 to 55%, the porosity on the inner surface is 10 to 30%, more preferably 12 to 20%, and the porosity on the outer surface is 10 to 30%, more preferably 12 to 20%, and the oxygen gas flux is 0.1 to 900 l / min · m ² · atm, and more preferably 1.0 to 400 l / min · m ² · atm. Is desirable for use as a hollow fiber membrane for artificial lung.
That is, if the porosity is less than 10%, the gas exchange capacity may be insufficient, whereas if the porosity exceeds 60%, plasma may leak, and the outer surface porosity may be 10%. If it is less than%, the gas exchange capacity may be insufficient due to insufficient formation of communication holes in the pores of the hollow fiber membrane, while if the open area ratio exceeds 30%, the communication holes may be It becomes simple and there is a risk of plasma leakage.

Next, a membrane oxygenator using the porous hollow fiber membrane produced by the present invention will be described. As the membrane oxygenator 50, FIG. 2 shows an assembled state of the hollow fiber membrane oxygenator which is one embodiment thereof. The hollow fiber membrane-type artificial lung 50 accommodates a cylindrical housing 51 and 10,000 to 60,000 hollow fiber membranes, which are gas exchange membranes 52 and spread throughout the housing 51. The hollow fiber membrane has a large number of fine pores in its wall that form a gas flow path that connects the inside and the outside of the hollow fiber membrane. Both ends of the hollow fiber membrane 52 are liquid-tightly fixed to the housing 51 by partition walls 53 and 54 in a state where the respective openings are not closed. By the partition walls 53 and 54, the inside of the housing 51 is formed inside the hollow fiber membrane and the oxygen chamber 56 which is the first mass transfer chamber formed by the outer wall of the hollow fiber membrane, the inner wall of the housing 51 and the partition wall. It is partitioned into a blood circulation space that is a second mass transfer chamber.

The housing 51 is provided with an inflow port 57 for gas containing oxygen near one end and an outflow port 58 near the other end. Further, on the outside of the partition wall 53, the blood inlet 60 and the annular convex portion 6 are provided.
1 is fixed by a screw ring 64, and the blood outlet 6 is provided outside the partition wall 54.
5 and the flow path forming member 67 having the annular convex portion 66 are fixed by the screw ring 68. And the flow path forming member 6
The protrusions 70, 71 of the protrusions 3, 67 are in contact with the partition walls 53, 54, and the outer peripheral edges of the protrusions 70, 71 have at least two holes 75, 76 provided in the screw rings 64, 68, respectively. , 77, 78 is filled with a sealant, and the flow path forming members 63, 67 are liquid-tightly fixed to the partition walls 53, 54.

In the above description, the screw ring is used. However, the present invention is not limited to this, and the flow path forming member may be directly fused to the housing by using high frequency waves, ultrasonic waves, or the like. You may use and adhere. further,
Instead of the sealing agent, an O-ring made of silicone rubber or the like may be used to seal the flow path forming member to the partition wall in a liquid-tight state. In the above description, the case where blood is allowed to flow into the hollow fiber membrane and the oxygen-containing gas is allowed to flow to the outside of the hollow fiber membrane has been described, but the present invention is not limited to this, and blood is allowed to flow to the outside of the hollow fiber membrane. Alternatively, it may be of a type in which an oxygen-containing gas is introduced into the hollow fiber membrane. In this case, it is not necessary to provide a flow path forming member on the outflow side of the oxygen-containing gas, and the partition wall end may be opened.

[0029]

EXAMPLES Next, the present invention will be described in more detail by way of examples. (Example 1) Liquid paraffin (number average molecular weight 322, manufactured by Matsumura Oil Research Institute, trade name Moresco White p-70) per 100 parts by weight of a highly crystalline propylene homopolymer having a melt index (MI) of 23. 200 parts by weight,
0.3 parts by weight of a crystal nucleating agent [1,3,2,4 bis (p-methylbenzylidene) sorbitol, manufactured by Shin Nippon Science Co., Ltd., gelol MD]] is mixed and melted by a twin-screw extruder. The mixture was kneaded, extruded, and then pelletized. Using a short-axis extruder, which is an apparatus as shown in FIG. 1, the pellets are rotated at an extrusion screw rotation speed of 30 rpm, a spinneret temperature of 160 ° C., a winding speed of 140 rpm, and the distance between the spinneret device and the cooling solidified liquid. It was performed at 10 cm.

As the cooling and solidifying liquid, a mixture of polyethylene glycol (average molecular weight 200) and water in a ratio of 3: 1 was used, and the temperature of the cooling and solidifying liquid was 25 ° C. Then, as shown in FIG. 1, the discharged hollow material 1
6 is dropped in the air for a predetermined distance and introduced into the cooling tank 18,
The hollow solid 16 and the cooling solidification liquid 17 are brought into contact with the cooling solidification liquid 17, and the cooling solidification liquid is introduced into the cooling solidification liquid flow pipe 19 which is provided downward through the bottom of the cooling tank 18. 17 was made to flow down, and the hollow material 16 was brought into parallel flow contact along the flow. Then, the solidified hollow material 16 is led to a shower conveyor type extractor 27 in which an organic filler and polyethylene glycol are dissolved and polypropylene is not dissolved, and a shower conveyor type extractor 27 is sprinkled in a shower shape to adhere to the organic filler and the surface. After polyethylene glycol was extracted and removed, it was led out from the extractor 27 by the drive roll 22, passed through the heat treatment device 30, and wound by the bobbin 32 of the winder 31. The porous hollow fiber membrane produced in this way has an inner diameter of 220 μm, an outer diameter of 300 μm, a film thickness of 40 μm,
The porosity was 38%, the outer surface porosity was 17%, and the inner surface porosity was 19%.

Example 2 The procedure of Example 1 was repeated, except that a 1: 1 mixture of polyethylene glycol (average molecular weight 200) and water was used as the cooling and solidifying solution. The porous hollow fiber membrane thus produced has an inner diameter of 205 μm, an outer diameter of 295 μm, a film thickness of 45 μm, a porosity of 47%, an outer surface porosity of 20%, and an inner surface porosity of 20%. It was 20%.

Comparative Example 1 The procedure of Example 1 was repeated, except that only polyethylene glycol (average molecular weight 200) was used as the cooling and solidifying liquid. The porous hollow fiber membrane thus produced has an inner diameter of 227 μm and an outer diameter of 313.
μm, film thickness 43 μm, porosity 48%, outer surface porosity 38%, inner surface porosity 25%.

(Example 3) Hollow fiber produced in Example 1
About 20,000 membranes are stored in the housing, and the membrane area is 1.
8m 2. Create a hollow fiber membrane type oxygenator with the structure shown in Fig. 2 of 2.
I made it.

(Example 4) Hollow fiber produced in Example 2
About 20,000 membranes are stored in the housing, and the membrane area is 1.
8m 2. Create a hollow fiber membrane type oxygenator with the structure shown in Fig. 2 of 2.
I made it.

Comparative Example 2 Hollow fiber produced in Comparative Example 1
About 20,000 membranes are stored in the housing, and the membrane area is 1.
8m 2. Create a hollow fiber membrane type oxygenator with the structure shown in Fig. 2 of 2.
I made it.

[Experiment] Using the hollow fiber membrane type artificial lungs of Examples 3 and 4 and Comparative Example 2, the following experiment was conducted. (Experiment 1) Using the hollow fiber membrane-type artificial lungs of Examples 3 and 4 and Comparative Example 2, heparin-added bovine blood with Ht of 30% was added to the blood flow rate 5
Blood circulation was performed at 1 / min, artificial lung back pressure (pressure applied to the blood outlet side of the artificial lung) 400 mmHg, and oxygen gas flow rate 5 l / min. Then, near the gas outlet (outlet on the lower side of the housing), visual confirmation of plasma outflow and detection confirmation using a test paper for protein detection (Terumo Co., Ltd., Uriace) in the gas outlet Was done in combination with. In the artificial lungs of Examples 1 and 2, plasma leakage was not detected during the 72 hours from the start of circulation to the end when the detection was confirmed visually and by both test strips for protein detection. Further, in the artificial lung of Comparative Example 2, plasma leakage was not confirmed by visual detection and confirmation, but detection by protein test strips was confirmed.
Protein leakage was confirmed 52 hours after the start of circulation.

(Experiment 2) Using the hollow fiber membrane-type artificial lungs of Examples 3 and 4 and Comparative Example 2, an experiment was conducted on oxygen addition ability and carbon dioxide gas removal ability under the following conditions. The following conditions are based on the American Medical Instrumentation Promotion Association standard (AAMI standard).

(1) Preparation of venous blood Fresh heparin-added bovine blood was flown into an artificial lung for venous blood preparation, and a mixed gas of carbon dioxide gas, nitrogen gas and oxygen gas was blown to obtain an oxygen saturation of 65% and carbon dioxide gas content. Pressure 45mmHg, temperature 37 ℃
Venous blood was prepared. Hemoglobin amount is 12g / 100
ml, base exis is 0 with sodium bicarbonate
Corrected to.

(2) Experimental procedure The prepared venous blood was 2000 ml / min, 4000 ml
/ Min, 6000ml / min, 8000ml / mi
Examples 3 and 4 and Comparative Example 2 at respective flow rates of n.
Flowing into the hollow fiber membrane type artificial lung of 100% oxygen gas V / Q
The blood was blown in such a manner that = 1 (oxygen gas flow rate / blood flow rate = 1), and blood was collected before the blood inlet (Sv) and after the blood outlet (Sa) of the artificial lung. About the collected blood,
The oxygen saturation and the amount of hemoglobin were measured by a hemooximeter (manufactured by Radiometer, OMS2), and the carbon dioxide concentration in the exhaust gas was quantified by a blood gas analyzer (manufactured by Radiometer, ALB30).

The oxygen gas transfer amount was calculated by the following formula. Oxygen gas transfer rate [ml / min] = [Hb x (So-Si) x 1.
34 × QB] / 10,000 Hb: Hemoglobin amount [g / 100 ml] So: Oxygen saturation of blood outlet side [%] Si: Oxygen saturation of blood inlet side [%] QB: Blood flow rate [ml / min]

The transfer amount of carbon dioxide was calculated by the following formula. Carbon dioxide transfer rate [ml / min] = [VEO ₂ × CO ₂ cont
nt] / 100 VEO ₂ : blown oxygen gas flow rate [ml / min] CO ₂ content: carbon dioxide concentration [%] in the exhaust gas The results are shown in Tables 1 and 2.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

The method for producing a porous hollow fiber membrane of the present invention comprises:
A kneaded product obtained by kneading polypropylene, an organic filler that is uniformly dispersed in polypropylene under melting of the polypropylene, and a crystal nucleation agent is discharged in a molten state from an annular spinning hole into a hollow shape. The kneaded product is cooled and solidified by bringing it into contact with a cooling and solidifying liquid consisting of a mixture of polyethylene glycol and water, and then the hollow and kneaded product which is cooled and solidified is an extract which dissolves the organic filler without dissolving the polypropylene. Since the organic filler is extracted and removed by bringing it into contact with each other, it is possible to easily produce a hollow fiber membrane in which plasma does not leak even when the blood is circulated for a long time when used in an artificial lung.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a production apparatus used in the method for producing a porous hollow fiber membrane of the present invention.

FIG. 2 is a partial cross-sectional front view showing an example of a membrane oxygenator produced by using the porous hollow fiber membrane produced according to the present invention.

[Explanation of reference numerals] 1 hollow fiber membrane production apparatus 11 spinning compound (kneading material for spinning) 12 hopper 13 single-screw extruder 14 spinning apparatus 15 spinneret device 16 hollow material 17 cooling solidification liquid 18 cooling tank 19 cooling solidification liquid Distribution pipe 20 Solidification tank 22 Drive roll 23 Circulation line 25 Extraction liquid shower 26 Belt conveyor 27 Shower / conveyor type extractor 30 Heat treatment device 31 Winder 32 Bobbin 50 Hollow fiber membrane type artificial lung

Claims (2)

[Claims] 1. A kneaded product obtained by kneading polypropylene, an organic filler which is substantially uniformly dispersed in polypropylene under melting of the polypropylene, and a crystal nucleating agent is melted to form a hollow from an annular spinning hole. The hollow kneaded product is discharged, and the hollow kneaded product is brought into contact with a cooling and solidifying liquid composed of a mixture of polyethylene glycol and water to be solidified by cooling, and then the hollow and kneaded product which is cooled and solidified does not dissolve the polypropylene, and the organic filler is added. A method for producing a porous hollow fiber membrane, which comprises removing the organic filler by extracting the organic filler by contacting it with an extract solution that dissolves. 2. The cooling and solidifying liquid has a mixing ratio of polyethylene glycol and water of polyethylene glycol: water =
75-50: 25-50, The manufacturing method of the porous hollow fiber membrane of Claim 1.