JPH01168303A - Porous hollow yarn membrane and its preparation and pump-oxygenator - Google Patents

Abstract

PURPOSE:To obtain a hollow yarn membrane having high gas-exchange ability without leakage of plasma, by forming a highly dense layer of a polyolefin fine particle in inside of the hollow yarn membrane and forming a porous layer of the same particle bonded in chains in outside and making the rapture strength of the membrane in the axial direction higher than a particular value. CONSTITUTION:An organic filler such as propylene polymers, fluid paraffins, etc., is kneaded with a crystal nucleating agent such as 1,3- or 2,4-bis(ethylbenzene) sorbitol, etc. A melt of the resulting mixture is spun from a ring form spinning nozzle, and spun hollow yarn is brought in contact with a refrigerating soln. such as halohydrocarbons, etc. Then, the organic filler is extracted by an extractant such as chlorofluorohydrocarbons and removed. The obtained porous hollow yarn membrane is stretched at 1-30% draft and then heated. Thus, a porous hollow yarn of a polyolefin having inner diameter 150-300mum, thickness 10-150mum, and rapture strength in the axial direction >=80g/yarn is obtained. The hollow yarn membrane is used for a gas-exchange membrane of a pump-oxgenator.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a porous hollow fiber membrane, a method for producing the same, and an oxygenator. Specifically, the present invention relates to a porous hollow fiber membrane having high gas exchange ability and excellent breaking strength, a method for producing the same, and an oxygenator using the porous hollow fiber membrane.

(Conventional technology) In recent years, in heart surgery, etc., the patient's blood is guided outside the body.
A hollow fiber membrane oxygenator is used in the extracorporeal circulation circuit to add oxygen and remove carbon dioxide. Hollow fiber membranes used in such artificial lungs include:
There are 2s types, homogeneous membranes and porous membranes. In a homogeneous membrane, the gas molecules that permeate dissolve in the membrane and diffuse, thereby allowing gas to move. A typical example of this is silicone rubber, which has been commercialized as a colopo membrane type lung.

However, silicone rubber is not known as a homogeneous membrane that can be used at present due to its gas permeability, and the silicone rubber membrane has a thickness of 100 μm due to its strength.
It cannot be less than that.

There is a limit to gas permeation through this slick, and the permeation of carbon dioxide gas is particularly poor. Furthermore, the silicone rubber has the drawbacks of being expensive and having poor processability.

On the other hand, in a porous membrane, the fine pores of the membrane are significantly larger than the gas molecules to be passed through, so that the gas passes through the pores as a volumetric flow. For example, various artificial lungs using porous membranes such as microporous polypropylene membranes have been proposed.

For example, polypropylene is processed using a hollow fiber manufacturing nozzle.
Spinning temperature 210-270℃, draft ratio 180-600
After melt spinning at 155°C or lower, the first stage heat treatment is performed at 155°C or lower, and 30 to 200% stretching is performed at lower than 110°C.
It has been proposed that porous polypropylene hollow fibers be manufactured by performing a second heat treatment at a temperature higher than or equal to the second heat treatment temperature and lower than 155°C (Japanese Patent Publication No. 56-52, 12
No. 3). However, in the porous hollow fiber membrane obtained in this way, the pores are physically formed by stretching the polypropylene hollow fibers, so the pores are also non-uniform, and the pores are distributed in the direction of the membrane thickness. Since the pores are linear pores that are substantially horizontal to each other, and the pores are generated by cracking in the axial direction of the hollow fiber depending on the degree of stretching, the cross section is approximately square or rectangular. In addition, the pores are continuous and penetrate almost linearly, and the porosity is high. Therefore, the porous hollow fiber membrane has high water vapor permeability, and not only does its performance deteriorate due to condensation water, but also plasma may leak out when blood is circulated for a long time, and its strength is low. There was a drawback.

From this point of view, as a method of imparting porosity without drawing, for example, polyolefin, an organic filler that can be uniformly dispersed in the polyolefin when the polyolefin is melted, and that is easily soluble in the extract liquid used. agent and a crystal nucleating agent, the kneaded product thus obtained is discharged from an annular spinning hole in a molten state, and the hollow material is brought into contact with a cooling solidification liquid that does not dissolve the polyolefin to cool and solidify, It has been proposed to produce a porous hollow fiber membrane by then bringing the cooled and solidified hollow material into contact with an extract that does not dissolve the polyolefin to extract and remove the organic filler (Japanese Patent Laid-Open No. 61-90705). issue). The porous hollow fiber membrane obtained in this way has smaller pores and more complex pore paths than the porous hollow fiber membrane obtained by the above-mentioned stretching method, so it has no effect on gas movement. However, it was sufficiently effective in suppressing permeation of plasma and water vapor, and the problem of plasma leakage as described above did not occur. Also, in terms of strength, the film exhibits relatively good strength because no excessive stretching is applied. However, it could not be said to be practically sufficient in terms of strength, and there remained room for further improvement.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide an improved porous hollow fiber membrane, a method for manufacturing the same, and an artificial lung.

Another object of the present invention is to provide a porous hollow fiber membrane with improved breaking strength, a method for producing the same, and an oxygenator. It is another object of the present invention to provide a porous hollow fiber membrane that has high gas exchange ability, no risk of plasma leakage during long-term use, and has excellent properties in terms of breaking strength, a method for producing the same, and an oxygenator. purpose.

(Means for solving the problem) The above objectives are as follows:
A porous polyolefin hollow fiber membrane of approximately circular shape with a diameter of ~150 μm, the inner surface of the hollow fiber membrane exhibits a dense layer in which fine polyolefin particles are tightly bonded, and the outer surface thereof has fine polyolefin particles bonded in a chain shape. This is achieved by a porous hollow fiber membrane characterized by exhibiting a porous snow layer with fine communicating pores formed from the inner surface to the outer surface, and having an axial breaking strength of 80 g/fiber or more. Ru.

The present invention also has a porosity of 5-60%, a gas flux of 0.1-], OOO! This shows a porous hollow fiber membrane with a capacity of J/min·m2·atm.

The present invention further provides a porous hollow fiber membrane in which the polyolefin is polypropylene.

The above objects are also achieved by kneading a polyolefin, an organic filler that is uniformly dispersed in the polyolefin when the polyolefin is melted and is easily soluble in the extract liquid used, and a crystal nucleating agent, and melting the kneaded product. The hollow material is discharged from an annular spinning hole in this state, and the discharged hollow material is cooled and solidified by contacting with a cooled assimilated liquid that does not dissolve the polyolefin, and then the cooled and solidified hollow material is brought into contact with an extraction liquid that does not dissolve the polyolefin. This method is achieved by a method for producing a porous hollow fiber membrane, which is characterized in that the organic filler is extracted and removed by the method, and the hollow fiber membrane thus obtained is subjected to a post-ripening treatment after stretching by 1 to 30%. Ru.

The present invention also provides a method for producing porous hollow fiber membranes which involves adding 5 to 30% stretching. The present invention further provides a method for producing a porous hollow fiber membrane in which stretching is applied by 10 to 25%. The present invention also provides a method for producing a porous hollow fiber membrane in which the polyolefin is polypropylene. The present invention further provides a method for producing a porous hollow fiber membrane in which the organic filler is a hydrocarbon whose boiling point is higher than the melting point of the polyolefin. The present invention further provides a method for producing a porous hollow fiber membrane in which the hydrocarbons are liquid paraffin or α-olefin oligomer. The present invention also provides a method for producing a porous hollow fiber membrane in which the amount of organic filler is 35 to 150 parts by weight based on 100 parts by weight of polyolefin. The present invention also provides a method for producing a porous hollow fiber membrane in which the crystal nucleating agent is an organic heat-resistant substance having a melting point of 150° C. or higher and a gelation point higher than the crystallization initiation temperature of the polyolefin used. The present invention also provides a method for producing a porous hollow fiber membrane in which the amount of the crystal nucleating agent blended is 0.1 to 5 parts by weight per 100 parts by weight of the polyolefin.

The above-mentioned aspects further provide that in an oxygenator comprising a hollow fiber membrane as a gas exchange membrane, the gas exchange membrane has an inner diameter of 150 mm.
A porous polyolefin hollow fiber membrane having a substantially circular shape of ~300 μm and a wall thickness of 10 to 150 μm, the inner surface of which exhibits a dense layer in which fine polyolefin particles are tightly bonded,
Moreover, the outer surface side exhibits a porous layer in which fine particles of polyolefin are bonded in original form, with fine communicating pores being formed from the inner surface side to the outer surface side, and the breaking strength in the axial direction is 80 g/
This is achieved by an artificial lung characterized by being more than a thread.

The present invention also provides a hollow fiber membrane with a porosity of 5 to 60% and a gas flux of 0.1 to 1000j/min-m2.
This shows an artificial lung that is an ATM. The invention further provides an artificial lung in which the polyolefin is polypropylene.

(Function) Therefore, the method for producing a porous hollow fiber membrane of the present invention includes a polyolefin, an organic filler that is uniformly dispersed in the polyolefin while the polyolefin is melted and is easily soluble in the extract liquid used, and A crystal nucleating agent is kneaded, the kneaded material is discharged in a molten state from an annular spinning hole, the discharged hollow material is brought into contact with a cooling solidification liquid that does not dissolve the polyolefin, and is cooled and solidified. The method is characterized in that the organic filler is extracted and removed by bringing the product into contact with an extract that does not dissolve the polyolefin, and the hollow fiber membrane thus obtained is stretched by 1 to 30% and then heat treated. It is something. The porous polyolefin hollow fiber membrane obtained by cooling and solidifying the organic filler blended into the molten dope of the raw material as described above and then extracting it with an extract liquid is also disclosed in JP-A-61-90705. Because the pores are small and the pore paths are complex, it has high gas permeability and does not cause the problem of plasma leakage. When a hollow fiber membrane is stretched at a specific ratio as described above and then heat treated, the breaking strength of the hollow fiber membrane can be significantly increased without substantially deteriorating its microstructure or gas permeability properties. It has been discovered that this can be improved.

Hereinafter, the present invention will be explained in more detail based on embodiments.

FIG. 1 is a schematic diagram showing the manufacturing steps in one embodiment of the method for manufacturing a porous hollow fiber membrane of the present invention. That is,
As shown in FIG. 1, in this embodiment, a blend 11 of a polyolefin, an organic filler, and a crystal nucleating agent is fed from a hopper 12 to a kneader, for example, a single screw extruder 13. After being melt-kneaded and extruded, it is sent to a spinning device 14 and discharged from an annular spinning hole (not shown) of a spinneret device 15 into a gaseous atmosphere, such as air, and the hollow material 16 that comes out is cooled and solidified. 17 is introduced into the cooling tank 18 containing the liquid, and is brought into contact with the cooling solidification liquid 17 to be cooled and solidified. In this case, the hollow object 16 and the cooled solidified liquid 1
For example, as shown in FIG.
It is preferable that the cooled solidified liquid 17 is allowed to flow down into one cooled solidified liquid distribution pipe provided downwardly through the bottom of the cooling liquid 8, and that the hollow object 16 is brought into cocurrent contact with the flow. . The cooled solidified liquid 17 that has flowed down is received and stored in a solidification tank 20, into which the hollow object 16 is introduced, and the direction is changed by a deflection frame 21 to bring it into sufficient contact with the cooled solidified liquid 17 and solidify it. . The accumulated cooled solidified liquid 16 is discharged from a circulation line 23 and circulated to the cooling tank 18 by a circulation pump 24. Next, the solidified hollow object 16 is
A drive roll 22a leads the extractor to a shower conveyor type extractor 27 which showers down an extract 25 which dissolves the organic filler but does not dissolve the polypropylene. In this extractor 27, the hollow material 16 is fully contacted with the extraction solution 25 while being conveyed on the belt conveyor 26, and the remaining organic filler is extracted and removed, and the hollow fiber membrane 16° is made porous. becomes. Drive roll 22b
The hollow fiber membrane 16 led out from the extractor 27 by
After passing through further steps (not shown) such as re-extraction and drying as necessary, the heat treatment device 30 is guided by the drive roll 22c. However, the drive roll 22
A tension is exerted between C and the 10th roller 29 of the heat treatment device 30, and the hollow fiber membrane 16'' is heated at a predetermined ratio, that is, 1
~30% stretch is added. The inside of the heat treatment device 30 is maintained at a predetermined temperature condition by heating means such as a heater 28, and the hollow fiber membrane 16- is heat treated while moving between the rollers in the heat treatment device 30, and the membrane structure is stabilized. I can't help it. Hollow fiber membrane 1 led out from heat treatment device 30
6' is wound onto a bobbin 32 in a winding device 31.

Polyolefins used as raw materials in the present invention include propylene homopolymers, ethylene homopolymers, and block polymers containing propylene as a main component with other monomers, and the melt index (M, 1.) is 5. ~70 is preferable, especially M,
1. is preferably 10 to 40. Further, among the polyolefins, propylene homopolymer is particularly preferable,
Among these, those with high crystallinity are most preferred.

The organic filler must be able to be uniformly dispersed in the polyolefin while it is melted, and be easily soluble in the extract as described below. Such organic fillers include liquid paraffin (number average molecular weight 100-2.000), α-olefin oligomers [e.g. ethylene oligomer (number average molecular weight 100-2.000>), propylene oligomer (number average molecular weight 100-2.000), ,000>, ethylene-propylene oligomer (number average molecule x 100 to 2,000), etc.],
Paraffin wax (number average molecular weight 200-2.500
>, various hydrocarbons, etc., preferably liquid paraffin.

The blending ratio of polypropylene and the organic filler is 35 to 1 part by weight of the organic filler per 100 parts by weight of polypropylene.
The amount is 50 parts by weight, preferably 50 to 100 parts by weight. That is, if the organic filler is less than 35 parts by weight, a porous hollow fiber membrane having sufficient gas permeability cannot be obtained;
This is because if it exceeds 0 parts by weight, the viscosity becomes too low and the moldability into hollow shapes deteriorates. Such raw material formulations are prepared (designed) by a pre-kneading method in which a mixture of a predetermined composition is melt-kneaded using an extruder such as a twin-screw extruder, extruded, and then pelletized. .

In the present invention, the crystal nucleating agent blended into the raw material has a melting point of 150°C or higher (preferably 200-250°C).
°C) and has a gel point higher than the crystallization initiation temperature of the polyolefin used. The reason for blending such a crystal nucleating agent is to reduce the size of polyolefin particles, thereby narrowing the voids between the particles, that is, communicating pores, and increasing the pore density. -For example,
For example, 1,3,2,4-dibenzylidene sorbitol, 1,3,2,4-bis(p-methylbenzylidene) sorbitol, 1,3,2,4-bis(p-ethylbenzylidene) sorbitol, bis(4 -1-butylphenyl)
Sodium phosphate, sodium benzoate, adipic acid,
Examples of crystal nucleating agents include talc and kaolin.

As a crystal nucleating agent, benzylidene sorbitol, especially 1,3,2,4-bis(p-ethylbenzylidene) sorbitol, and 1,3,2,4-bis(p-methylbenzylidene) sorbitol are known to elute into the blood. Less is preferable.

The blending ratio of polypropylene and the crystal nucleating agent is 0.00 parts by weight of the crystal nucleating agent per 100 parts by weight of polypropylene.
It is 1 to 5 parts by weight, preferably 0.83 to 1.0 parts by weight.

The raw material mixture thus prepared is further melted and kneaded using an extruder such as a single-screw extruder at a temperature of, for example, 160 to 250°C, preferably 180 to 220°C, and quantitative analysis is performed if necessary. A high gear pump is used to discharge the spinning device into a gas atmosphere from an annular hole to form a hollow material. Note that an inert gas such as nitrogen, carbon dioxide, helium, argon, or air may be self-suctioned into the center of the annular hole, or if necessary, these inert gases may be forcibly introduced. You can. Subsequently, the hollow material discharged from the annular hole is dropped and then brought into contact with the cooled solidified liquid in the cooling tank. The falling distance of the hollow object is preferably 5 to 1000 mm, particularly preferably 10 to 500 mm. That is, if the falling distance is less than 5 mm, pulsation may occur and the hollow object may be crushed when it enters the cooled and solidified liquid. The hollow object has not yet solidified sufficiently in this cooling tank, and since the central part is gaseous, it is easily deformed by external force.
The cooled solidified liquid 17 is caused to flow down into the cooled assimilated liquid distribution pipe 19 that is provided downwardly through the bottom of the hollow body 8, and the hollow object 16 is brought into co-current contact with the hollow object 16 along the flow. The shaped object 16 can be forcibly moved and deformation of the hollow shape due to external force (fluid pressure, etc.) can be prevented. At this time, the flow rate of the cooled and solidified liquid is sufficient under natural flow. The cooling temperature at this time is 10 to 60°C, preferably 20 to 50°C.
It is. In other words, at temperatures below 10°C, the cooling assimilation rate is too fast and most of the thick wall becomes a dense layer, resulting in low gas exchange ability, while at temperatures above 60°C, the polyolefin crystallizes. Not only does the velocity become slow and the diameter of the particles on the outer surface become too large, making the microscopic pores too large, but also the dense layer becomes extremely thin, or even completely disappears at higher temperatures. This is because there is a risk that clogging or plasma leakage may occur if used in a vacuum cleaner.

As the cooling solidification liquid, any substance can be used as long as it does not dissolve the polyolefin and has a high specific boiling point. - Examples include alcohols such as methanol, ethanol, propatools, butanols, hexanols, octatools, and lauryl alcohol; liquid fatty acids such as oleic acid, palmitic acid, myristic acid, and stearic acid; Alkyl esters (e.g. esters of methyl, ethyl, isopropyl, butyl, etc.),
Liquid hydrocarbons such as octane, nonane, decane, kerosene, light oil, toluene, xylene, methylnaphthalene, etc., 1,1
．． 2-trichloro-1,2゜2-trifluoroethane,
trichlorofluoromethane, dichlorofluoromethane,
Examples include halogenated hydrocarbons such as LL, 2.2=tetrachloro-1,2-difluoroethane, but are not limited to these.

The hollow material cooled and solidified in the cooling solidification tank is sent to an extractor or the like via a redirector, where the organic filler is dissolved and extracted. The method for dissolving and extracting the organic filler is not limited to the shower method in which the extract is showered onto a hollow object on a belt conveyor as shown in FIG. Any method may be used as long as the hollow material can come into contact with the extract, such as a method of immersing the skein in the extract solution when the collected hollow material is rolled back into another skein. It is also possible to combine two or more of these methods.

As the extraction liquid, any liquid 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. - Examples include alcohols such as methanol, ethanol, propatools, butanols, pentanols, hexanols, octatools, lauryl alcohol, 1,1,2-trichloro-1,2,2-tri Fluoroethane, trichlorofluoromethane, dichlorofluoromethane, 1,1,2.
There are halogenated hydrocarbons such as 2-tetrachloro-1,2-difluoroethane, etc. Among these, halogenated hydrocarbons are preferable from the viewpoint of extraction ability for organic fillers, and chlorinated hydrocarbons are particularly preferred from the viewpoint of safety to the human body. Fluorinated hydrocarbons are preferred.

The porous hollow fiber membrane obtained in this way is then coated with 1
~30%, preferably 5-30%, more preferably 10
~25% stretching treatment is added.

That is, if the stretching is 1% ungrooved, the breaking strength of the hollow fiber membrane cannot be substantially improved; on the other hand, if the stretching is 30%
This is because if it exceeds %, it will affect the fine structure of the hollow fiber membrane, causing changes in porosity, gas flux, etc., which may lead to a decrease in gas exchange ability and plasma leakage. Note that the stretching method is not particularly limited, but
As shown in Figure 1, between the drive roll and the roller,
Alternatively, it is desirable to apply tension between rollers.

The hollow fiber membrane thus stretched at a predetermined ratio as described above is further subjected to heat treatment. Heat treatment is performed in a gaseous atmosphere such as air, nitrogen, carbon dioxide, etc. at 70 to 1
5 seconds to 1 at a temperature of 30°C, preferably 100-120°C
This is carried out for 20 minutes, preferably 10 seconds to 60 minutes. This heat treatment stabilizes the structure of the hollow fiber membrane and increases its dimensional stability.

The porous hollow fiber membrane thus obtained has an inner diameter of 15
It is a substantially circular porous polyolefin hollow fiber membrane having a wall thickness of 0 to 300 μm, preferably 180 to 250 μm, and preferably 20 to 100 μm. In addition, the cross-sectional structure of the hollow fiber membrane varies slightly depending on the manufacturing conditions of the hollow fiber membrane, but generally the inner surface shows a dense layer in which fine polyolefin particles are tightly bonded, and the outer surface has fine polyolefin particles. It exhibits a porous layer connected in a chain shape, and fine communicating pores are formed from the inner surface to the outer surface. However, as described above, the porous hollow fiber membrane of the present invention has an improved breaking strength because it is made porous by the extraction method and then subjected to stretching and heat treatment at a predetermined ratio. 80 g/yam, more preferably 85 g/yam or more.

In this way, the porous hollow fiber membrane of the present invention has a breaking strength of
Since it has an extremely high value of 80 g/fiber or more, there is little risk of the hollow fibers breaking when actually assembled into a module, and the effective membrane area in the module can be improved.

Furthermore, in the porous hollow fiber membrane of the present invention, the porosity is 5 to 5.
60%, more preferably 30-50%, and the gas flux is 0.1-1000. Q/min・m2・atm,
More preferably 300 to 800 p/min・m2・a
tm is a desired characteristic for use in an oxygenator.

The oxygenator of the present invention is characterized in that it is equipped with a porous hollow fiber membrane with improved breaking strength as a gas exchange membrane as described above, and the reduction in effective membrane area due to breakage of the hollow fibers is prevented. There is less risk of this occurring and higher gas exchange performance can be obtained.

Hereinafter, the structure of the hollow fiber membrane oxygenator of the present invention will be explained in more detail based on the drawings.

FIG. 2 shows an embodiment of the hollow fiber membrane oxygenator of the present invention, in which blood is circulated inside the hollow fiber membrane and oxygen-containing gas is blown outside the hollow fiber membrane (first embodiment). This shows the assembled state. That is, the hollow fiber membrane oxygenator 51
is equipped with a housing 52, and this housing 5
2 is provided with annular male threaded mounting covers 54 and 55 at both ends of the cylindrical body 53, and inside the housing 52, there are a large number of screws, for example 10,000 to 60,000, having the characteristics described above. 16 degrees of porous hollow fiber membranes are arranged in parallel and spaced apart from each other along the longitudinal direction of the housing 52. Both ends of this porous hollow fiber [16'' are liquid-tightly supported by partition walls 57.58 within the mounting cover 54.55 with their respective openings not being closed. 58 constitutes a gas chamber 59 together with the outer circumferential surface of the porous hollow fiber membrane 16' and the inner surface of the housing 52, and a blood circulation space (58) which is closed and is formed inside the porous hollow fiber membrane 16'.
(not shown) and the gas chamber 59. Further, one mounting cover 54 is provided with an oxygen-containing gas inlet 60 for supplying oxygen-containing gas, and the other mounting cover 55 is provided with an oxygen-containing gas outlet 61 for discharging oxygen-containing gas. There is.

The inner surface of the cylindrical main body 53 of the housing 52 may be provided with a restricting portion 62 for restricting the diaphragm and protruding from the center in the axial direction. By providing the restricting portion 62 in the center in this way, it is possible to improve the gas exchange efficiency. This restraint part 62 is integrally formed on the inner surface of the cylindrical body 53, and is used to hold a hollow fiber bundle 63 consisting of a large number of porous hollow fiber membranes 16' inserted into the cylindrical body 53. The outer circumference is tightened. In this way, the hollow fiber bundle 63 is constricted at the center in the axial direction, forming a constricted portion 64. Therefore, the filling rate of the hollow fiber membrane differs in each part along the axial direction, and is highest in the central part. In addition, the desirable filling rate in each part is as follows. First, as shown in FIG. 3, the filling rate A in the central constricted portion 64 is about 60 to 80%, and the filling rate B in the other cylindrical body 53 is about 30 to 60%. both ends,
In other words, the filling factor C on the outer surface of the partition walls 57 and 58 is approximately 20
~40%.

Next, the formation of the partition walls 57 and 58 will be described. As mentioned above, the partition walls 57 and 58 perform the important function of isolating the inside and outside of the porous hollow fiber membrane 16-. Typically, the partition walls 57, 58 are made of a highly polar polymeric potting material, such as polyurethane, silicone, etc.
It is made by pouring epoxy resin or the like onto the inner wall surfaces of both ends of the housing 52 using a centrifugal injection method and hardening it.

More specifically, first, a large number of porous hollow fibers [16°] longer than the length of the housing 52 are prepared, and after sealing both open ends with a resin with high viscosity, the cylindrical body 53 of the housing 52 is Place them side by side inside. After this,
Attachment is done by completely covering both ends of the porous hollow fiber membrane 16' with a mold cover of a size above the cover 54, 55, and rotating the housing 52 around the central axis of the housing 52. The polymer potting material is poured in from the side. Once the resin has hardened after pouring, the mold cover is removed and the outer side of the resin is cut with a sharp knife to expose both open ends of the porous hollow fibers M16. to be exposed to. Thus, partition walls 57 and 58 are formed.

The outer surfaces of the partition walls 57 and 58 are respectively covered with channel forming members 65 and 66 having annular projections. The flow path forming members 65, 66 each consist of a liquid distribution member 67, 68 and a screw ring 69, 70, and this liquid distribution member 67
．． The protrusion 7 is an annular convex portion provided near the peripheral edge of the ridge 7.
Blood inflow chambers 73 and 74 are respectively formed by bringing the end faces of 1.72 into contact with the partition walls 57 and 58, and fixing the six screw rings and 70 by screwing them onto the covers 54 and 55, respectively. has been done. The flow path forming members 65 and 66 are provided with a blood introduction lower part 5 and a blood leading part lower part, respectively.

At least two holes 77,78 communicating with the gap are formed in the gap at the peripheral edge of the partition 57,58 formed by the partition 57,58 and the flow path forming member 65,66.
and 79.80 are sealed so as to be in contact with the partition wall 57.58. Alternatively, it can be sealed via an O-ring (not shown).

Next, FIG. 4 shows another embodiment of the hollow fiber membrane oxygenator of the present invention, in which blood is circulated outside the hollow fiber membrane and oxygen-containing gas is blown into the inside of the hollow fiber membrane (second embodiment). The assembled state of the embodiment) is shown. That is, the hollow fiber membrane oxygenator 81 is
The housing 82 is provided with annular covers 84 and 85 attached to both ends of the cylindrical body 83.
The housing 82 is provided with a large number of porous hollow fiber membranes 16', for example, 10,000 to 60,000 porous hollow fiber membranes 16' having the above-mentioned characteristics, spread throughout the housing 82.
are arranged in parallel and spaced apart from each other along the longitudinal direction. Both ends of the porous hollow fiber membrane 16' are supported in a liquid-tight manner by partition walls 87, 88 within the mounting cover 84, 85, with the respective openings not being closed.

In addition, each of the partition walls 87 and 88 has a porous hollow fiber membrane 16-
The blood chamber 89 along with the outer peripheral surface and the inner surface of the housing 82
, and the above-mentioned porous hollow fiber M16
- This is to isolate eight blood chambers from an oxygen-containing gas circulation space (not shown) formed inside the chamber. Further, a blood inlet 95 for supplying blood is provided on one side of the housing 82, and a blood outlet 96 for discharging blood is provided on the other side of the housing.

On the inner surface of the cylindrical main body 83 of the housing 82, an aperture restricting portion 92 may be provided that protrudes from the center in the axial direction. That is, the restraint part 92 is formed integrally with the cylindrical body 83 on the inner surface of the cylindrical body 83, and
The outer periphery of a hollow fiber bundle 93 consisting of a large number of porous hollow fiber membranes 16' inserted therein is tightened. In this way, the hollow fiber bundle 93 is narrowed at the center in the axial direction, forming a narrowed portion 94. Therefore, the filling rate of the hollow fiber membrane differs in each part along the axial direction, and is highest in the central part. Also, cover 84.
85 are formed with an oxygen-containing gas inlet 90 and an oxygen-containing gas outlet 91, respectively. Other parts, forming methods, etc. are similar to the hollow fiber membrane oxygenator according to the first embodiment described above, and therefore their explanations will be omitted.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 4 130 parts by weight of liquid paraffin (number average molecular weight 324) and 1.3.2.4 as a crystal nucleating agent to 100 parts by weight of propylene homopolymer having a melt index (M, 1.) of 23. - Add 0.5 parts by weight of bis(ethylbenzene) sorbitol and use a twin-screw extruder (Ikegai Iron Works ■)
The mixture was melt-kneaded using a PCM-30-25 manufactured by PCM-30-25, a manufacturer of PCM-30-25 manufactured by PCM Corporation, and then extruded and pelletized. The pellets are processed using a device as shown in Fig. 1, that is, a single screw extruder (manufactured by Kasamatsu Seisakusho, WO-3
0) 13 at 180°C and 3.6 to 5.0 g/mm from an annular spinning hole with a core diameter of 4 mm, an inner diameter of 6 mm, an outer diameter of 7 mm, and a land length of 15 mm.

It was discharged into the air at a discharge amount of , and the hollow object 16 was allowed to fall. Note that the falling distance was 20 to 30 mm. Subsequently, the hollow body 16 is cooled and solidified liquid 17 in a cooling tank 18 with Freon 11.3 (1,1,2-trichloro-1,2,
2-trifluoroethylene), and then brought into co-current contact with the cooled solidified liquid 17 flowing down naturally in the cooled solidified liquid flow pipe 19 for cooling. Note that the temperature of the cooled assimilate liquid 17 at this time was 20°C. Next, the hollow object 16 is introduced into the cooled solidified liquid 17 in the solidification tank 20, and then changed direction by the change-of-direction rod 21, guided to the drive roll 22a with a winding speed of 80 m/min, and continuously conveyed to the shower conveyor. In the type extractor 27, the liquid paraffin is completely extracted with an extraction liquid 25 made of Freon 113. The hollow fiber membrane 16- imparted with porosity in this manner is taken out from the extractor 27 by the drive roll 22b and placed in the heat treatment device 30.
The drive roll 22b is stretched at the ratio shown in Table 1 between the drive roll 22b and the 10th rule 29 of the heat treatment device 30, and further stretched by 110 mm while passing through the heat treatment device W30.
A heat treatment of 20 seconds was applied at °C.

The hollow fiber membrane 16- that has passed through the heat treatment device 30 is passed through the winding machine 33.
It was wound onto bobbin 34.

The shape of the porous hollow fiber membrane thus obtained (
Measurements were made regarding the inner diameter/thickness), porosity, gas flux, oxygen gas addition ability, carbon dioxide removal ability, plasma leakage, and breaking strength. The results obtained are shown in Table 1.

Comparative Example 1 For comparison, porous hollow fiber membranes were prepared in the same manner as in Examples 1 to 4, except that no stretching treatment was performed, and the shape (inner diameter/thickness) and hollow fiber membranes were determined in the same manner as in Examples 1 to 4. Porosity, gas flux, oxygen gas addition ability, carbon dioxide removal ability, plasma leakage,
and measurements of breaking strength were carried out. The results obtained are shown in Table 1.

Grain ratio example 2 Porous hollow fiber membranes were prepared in the same manner as Examples 1 to 4 except that the stretching ratio was changed as shown in Table 1 for grain ratio, and the obtained porous hollow fiber membranes were Shape (inner diameter/thickness N)
, porosity, gas flux, oxygen gas addition capacity, carbon dioxide removal capacity, plasma leakage, and breaking strength were measured. The results obtained are shown in Table 1.

The definitions and measurement methods of each term in these Examples and Comparative Examples are as follows.

Ten of the obtained hollow fiber membranes are arbitrarily taken out and cut into rounds with a length of about 0.5 mm using a sharp razor. The cross section was projected onto a universal projector using a ConProfile Projector-V-12, and a ConDigital Counter C was used as a measuring instrument.
M-63), measure its outer diameter d1 and inner diameter d2, and find the wall thickness t.
was calculated using t=d1-d2, and the average value of the 10 pieces was taken as the average value.

Porosity (%) Take about 2g of the obtained hollow fiber membrane and use a sharp razor to cut it into a 5m
Cut into rounds less than m long. The obtained sample was heated to 1000k using a mercury porosimeter (Carlo Erba Model 65A).
Pressure is applied to g/cm2, and the porosity is obtained from the total pore volume (pore volume of the hollow fiber membrane per unit weight).

The hollow fiber membrane obtained with gas flux has an effective length of 14 cm and a membrane area of 0.02
After creating a 5m2 mini module and closing one end, apply a pressure of 1 atm inside the hollow fiber with oxygen, and measure the flow rate of oxygen gas when it reaches a steady state with a flowmeter (manufactured by Kusano Rikagaku Kiki Seisakusho, The value was taken as the value read using a float meter).

-, Sourium additive 1, Gas 2, Gas 5 (first embodiment) The obtained hollow fiber has an effective length of 140 mm and a membrane area of 5.4 m.
2 artificial lung module was created, and bovine blood (standard venous blood) was introduced into the hollow fiber in a single pass (Single Pat
h) at a flow rate of 6.0, Q/min, and pure oxygen was supplied to the outside of the hollow system. OJl/min.

The pH of bovine blood at the oxygenator inlet and outlet is
1 Partial pressure of carbon dioxide (Pco2), partial pressure of oxygen gas (Po2)
Blood gas measuring device (Radiometer, BG)
Type AB), and the partial pressure difference between the inlet and outlet of the oxygenator was calculated.

(Second embodiment) The obtained hollow fiber has an effective length of 90 mm and a membrane area of 2°Lm.
2 artificial lung module was created, and bovine blood (standard venous blood) was passed through the outside of the hollow fiber in a single pass (SingIe Pa,
th) at 6. Q, l! /min, and pure oxygen was introduced into the hollow system at a flow rate of 6.0. l! /min, and measured the pH, partial pressure of carbon dioxide gas (Pco2), and partial pressure of oxygen gas (Po2) of bovine blood at the inlet and outlet of the oxygenator using a blood gas measuring device (Radi Ometer, BGAB type).
The partial pressure difference between the inlet and outlet of the oxygenator was calculated.

An artificial lung module similar to the one used for the peritoneal plasma-dish specific oxygen gas addition and carbon dioxide removal capabilities was created, and was used for jugular venous and carotid artery cannulation using a mongrel (approximately 20 kg body weight).
The artificial lung module was installed in a partial VA bypass circuit by ion>, and extracorporeal circulation was performed for 30 hours, and the amount of plasma leaking from inside the hollow fiber was measured. Furthermore, even if no leakage was confirmed, a trace amount of plasma leakage was also confirmed by examining the protein reaction of droplets with water vapor outside the hollow fiber.

Prepare 10 hollow fiber membranes cut into lengths of approximately 10 cm, and measure each piece using Toyo Seiki's Strograph T under the following conditions. The average value was calculated.

Chuck used: wide box chuck Initial length: 25 mm Drawing speed: 50 mm/min Temperature: 23°C (blank below) As is clear from Table 1, stretching within the range of the present invention (5~
30%) added porous hollow fiber membranes (Examples 1-4)
is a porous hollow fiber membrane that was not subjected to stretching (Comparative Example 1)
), the breaking strength is significantly improved, and other properties remain essentially unchanged. On the other hand, those with stretching exceeding 30% (Comparative Example 2)
), it could not be said to be a preferable hollow fiber membrane due to problems such as plasma leakage.

(Effects of the Invention) As described above, the present invention has an inner diameter of 150 to 300 μm.
, a substantially circular porous polyolefin hollow fiber membrane with a wall thickness of 10 to 150 μm, the inner surface of the hollow fiber membrane exhibits a dense layer in which fine polyolefin particles are tightly bonded, and the outer surface thereof has fine polyolefin particles. A porous hollow body characterized by exhibiting a porous layer in which are bonded in a chain, with fine communicating pores formed from the inner surface to the outer surface, and having an axial breaking strength of 80 g/yarn or more. Because it is a thread membrane,
For example, when creating an oxygenator using the porous hollow fiber membrane, there is little risk of a decrease in the effective membrane area due to rupture of the hollow fiber membrane, and excellent gas exchange is achieved without causing problems such as plasma leakage. It shows efficiency. Furthermore, in the porous hollow fiber membrane of the present invention, the porosity is 5 to 6.
5 at 0%, gas flux 0.1-1OOON/mi
n −m 2 ·atm, and when the polyolefin is polypropylene, the performance will be even better, and it will be more suitable as a hollow fiber membrane for an oxygenator.

The present invention also provides a method of kneading a polyolefin, an organic filler that is uniformly dispersed in the polyolefin when the polyolefin is melted and is easily soluble in the extract liquid used, and a crystal nucleating agent, and bringing the kneaded product into a molten state. The hollow material is discharged from an annular spinning hole, and the discharged hollow material is cooled and solidified by contacting with a cooling solidification liquid that does not dissolve the polyolefin, and then the cooled and solidified hollow material is brought into contact with an extraction liquid that does not dissolve the polyolefin. This method of producing a porous hollow fiber membrane is characterized by extracting and removing the organic filler, stretching the hollow fiber membrane thus obtained by 1 to 30%, and then subjecting it to heat treatment. The breaking strength of the porous hollow fiber membrane can be improved without impairing the excellent pore structure, gas exchange efficiency, etc. of the porous hollow fiber membrane created by the method, and the porous hollow fiber membrane has the above-mentioned excellent properties. It is possible to produce porous hollow fiber membranes. Furthermore, in the method for producing a porous hollow fiber membrane of the present invention, the stretching ratio is 5 to 5.
30%, more preferably 10 to 25%, and if the heat treatment is carried out at 70 to 130°C for 5 seconds to 120 minutes, a porous membrane with a stable structure and excellent breaking strength and other properties can be obtained. In addition, the polyolefin is polypropylene, the organic filler is a hydrocarbon whose boiling point is higher than the melting point of the polyolefin, the hydrocarbon is liquid paraffin or an α-olefin oligomer, and the polyolefin is 100% by weight.
The blending amount of the organic filler is 35 to 150 parts by weight based on the weight of the polyolefin, and the crystal nucleating agent is an organic heat-resistant substance with a melting point of 150° C. or higher and a gel point higher than the crystal initiation temperature of the polyolefin used. When the amount of the crystal nucleating agent blended is 0.1 to 5 parts by weight per 100 parts by weight, the performance of the porous hollow fiber membrane obtained will be even more excellent.

Furthermore, the present invention provides an oxygenator comprising a hollow fiber membrane as a gas exchange membrane, wherein the gas exchange membrane has an inner diameter of 150 to
It is a porous polyolefin hollow fiber membrane of approximately circular shape with a diameter of 300 μm and a wall thickness of 10 to 150 μm, the inner surface of which exhibits a dense layer in which fine polyolefin particles are tightly bonded, and the outer surface of which has fine polyolefin particles arranged in a chain shape. The oxygenator is characterized by having a bonded porous layer with fine communication holes formed from the inner surface to the outer surface, and having an axial breaking strength of 80 g/thread or more. There is no risk of reduction in effective membrane area due to rupture of the thread membrane, and excellent gas exchange efficiency is exhibited without causing problems such as plasma leakage.

Furthermore, in the oxygenator of the present invention, the porosity of the hollow fiber membrane is 5 to 60%, the gas flux is 0.1 to 1000, and the Q
/min-m2 .atm, and when the polyolefin is polypropylene, the above-mentioned properties become even more excellent.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an apparatus that can be used in the method for producing a porous hollow fiber membrane according to the present invention, and FIG. 2 is a half-sectional view showing an embodiment of a hollow fiber membrane oxygenator according to the present invention. FIG. 3 is a sectional view showing various parts related to the hollow fiber membrane filling rate in the same embodiment, and FIG. 4 is a half sectional view showing another embodiment of the hollow fiber membrane oxygenator according to the present invention. 11... Raw material mixture, 12... Hopper, 13...
・Single screw extruder, 14... Spinning device, 15... Annular spinning hole, 16... Hollow object, 16''... Hollow fiber membrane, 1
7... Cooled solidified liquid, 18... Cooling tank, 19... Cooled solidified liquid distribution pipe, 20... Solidified tank, 21... Direction changing rod, 22a, 22b, 22 c... Drive roll,
23...Circulation line, 24...Circulation pump, 25.
...Extract liquid, 26...Belt conveyor, 27...Shower conveyor type extractor, 28...Heater, 29
... aging treatment equipment No. 10, 30... heat treatment equipment,
31... Winder, 32... Bobbin, 51.81...
・Hollow fiber membrane oxygenator, 52.82... Housing, 53.83... Cylindrical body, 57.58.87.88... Partition wall, 59.89... Gas chamber, 60.90 ...Oxygen-containing gas inlet, 61.91...
- Oxygen-containing gas outlet, 63.93...Hollow fiber bundle, 75.95...Blood inlet, 76.96...Blood outlet, 89...Blood chamber.

Claims (1)

[Claims] (1) The inner diameter is 150 to 300 μm, and the wall thickness is 10 to 150 μm.
It is a porous polyolefin hollow fiber membrane having an approximately circular shape of μm in diameter, and the inner surface of the hollow fiber membrane exhibits a dense layer in which fine polyolefin particles are tightly bonded, and the outer surface thereof has fine polyolefin particles bonded in a chain shape. A porous hollow fiber membrane exhibiting a porous layer with fine communicating pores formed from the inner surface to the outer surface, and having an axial breaking strength of 80 g/fiber or more. (2) Porosity is 5-60% and gas flux is 0.1
The porous hollow fiber membrane according to claim 1, which has a flow rate of ~1000 l/min.m^2.atm. (3) The porous hollow fiber membrane according to claim 1 or 2, wherein the polyolefin is polypropylene. (4) Knead a polyolefin, an organic filler that is uniformly dispersed in the polyolefin when the polyolefin is melted and is easily soluble in the extract liquid used, and a crystal nucleating agent, and then knead the kneaded product into a cyclic form in a molten state. The hollow material is discharged from a spinning hole, and the discharged hollow material is cooled and solidified by contacting with a cooling solidification liquid that does not dissolve the polyolefin, and then the cooled and solidified hollow material is brought into contact with an extractant that does not dissolve the polyolefin to form an organic filling. A method for producing a porous hollow fiber membrane, which comprises extracting and removing the agent, stretching the hollow fiber membrane thus obtained by 1 to 30%, and then subjecting it to heat treatment. (5) The method for producing a porous hollow fiber membrane according to claim 4, wherein stretching is applied by 5 to 30%. (6) The method for producing a porous hollow fiber membrane according to claim 5, wherein stretching is applied by 10 to 25%. (7) The method for producing a porous hollow fiber membrane according to any one of claims 4 to 6, wherein the heat treatment is performed at 70 to 130°C for 5 seconds to 120 minutes. (8) The method for producing a porous hollow fiber membrane according to any one of claims 4 to 7, wherein the polyolefin is polypropylene. (9) The method for producing a porous hollow fiber membrane according to any one of claims 4 to 8, wherein the organic filler is a hydrocarbon whose boiling point is higher than the melting point of the polyolefin. (10) The method for producing a porous hollow fiber membrane according to claim 9, wherein the hydrocarbon is a liquid paraffin or an α-olefin oligomer. (11) The method for producing a porous hollow fiber membrane according to any one of claims 4 to 10, wherein the amount of the organic filler blended is 35 to 150 parts by weight per 100 parts by weight of the polyolefin. (12) The crystal nucleating agent is an organic heat-resistant substance having a melting point of 150°C or higher and a gelling point higher than the crystallization initiation temperature of the polyolefin used, Claims 4-
The method for producing a porous hollow fiber membrane according to any one of Item 11. (13) The method for producing a porous hollow fiber membrane according to any one of claims 4 to 12, wherein the amount of the crystal nucleating agent is 0.1 to 5 parts by weight based on 100 parts by weight of the polyolefin. . (14) In an oxygenator comprising a hollow fiber membrane as a gas exchange membrane, the gas exchange membrane has an inner diameter of 150 to
It is a porous polyolefin hollow fiber membrane of approximately circular shape with a thickness of 300 μm and a wall thickness of 10 to 150 μm.The inner surface of the membrane is a dense layer in which fine polyolefin particles are tightly bonded, and the outer surface is made of chain-shaped fine polyolefin particles. 1. An oxygenator comprising a porous layer bonded to a porous layer in which fine communication holes are formed from the inner surface to the outer surface, and having an axial breaking strength of 80 g/thread or more. (15) The artificial lung according to claim 14, wherein the hollow fiber membrane has a porosity of 5 to 60% and a gas flux of 0.1 to 1000 l/min·m^2·atm. (16) The artificial lung according to claim 14 or 15, wherein the polyolefin is polypropylene.