Hollow fiber membrane filament, method for producing the same, oxygenation membrane, and oxygenation module

Abstract

The application provides a hollow fiber membrane filament and a preparation method thereof, an oxygenation membrane and an oxygenation device. The hollow fiber membrane filament comprises a first support layer, a second support layer and a skin layer arranged from inside to outside in a radial direction. The first support layer and the second support layer are both porous structures, and the pore size of the pores in the first support layer is greater than the pore size of the pores in the second support layer. The hollow fiber membrane filament has good oxygen permeation coefficient and plasma leakage resistance. When the hollow fiber membrane filament is used to prepare an oxygenation membrane, the oxygenation membrane has good gas exchange performance and a long plasma leakage resistance time, and meets the use requirement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a hollow fiber membrane filament, a preparation method thereof, an oxygenation membrane and an oxygenation assembly. BACKGROUND

[0002] In the field of medical devices, an extracorporeal membrane oxygenation (ECMO) device is a key device for life support and is a temporary cardiopulmonary support system. An oxygenation membrane is a core component of the ECMO device, and the oxygenation membrane is prepared from a hollow fiber membrane filament. The working principle of the ECMO device is to make the inner cavity of the hollow fiber membrane filament pass through oxygen, while the venous blood of a patient is introduced outside the oxygenation membrane. Oxygen in the inner cavity of the hollow fiber membrane filament exchanges with the venous blood to replace carbon dioxide therein and supplement oxygen, thereby completing blood oxygenation and being re-delivered back to the human body.

[0003] Based on this process, the hollow fiber membrane filament for the oxygenation membrane should have good gas exchange performance. SUMMARY

[0004] The present application aims to provide a hollow fiber membrane filament, a preparation method thereof, an oxygenation membrane and an oxygenation assembly, and aims to provide a hollow fiber membrane filament and an oxygenation membrane with a high oxygen permeation coefficient.

[0005] To achieve the above-mentioned purpose, the present application provides a hollow fiber membrane filament, which comprises a first support layer, a second support layer and a skin layer arranged from inside to outside along a radial direction, the first support layer and the second support layer are both porous structures, and the pore size of the pores in the first support layer is larger than the pore size of the pores in the second support layer.

[0006] Optionally, the gas flux of the hollow fiber membrane filament is 1.8ml / (min·cm 2 ·bar) to 4ml / (min·cm 2 ·bar).

[0007] Optionally, the thickness of the first support layer is 70um to 120um, the thickness of the second support layer is 10um to 40um, and the thickness of the skin layer is 0.08um to 1um.

[0008] Optionally, the tensile strength of the hollow fiber membrane filament is 1.0N to 2.3N, and the elongation at break is 100% to 300%.

[0009] To achieve the above-mentioned purpose, the present application further provides an oxygenation membrane, which is manufactured from the hollow fiber membrane filament according to any one of the preceding embodiments.

[0010] To achieve the above object, the present application further provides an oxygenation assembly comprising the oxygenation membrane as described above.

[0011] To achieve the above object, the present application further provides a preparation method of a hollow fiber membrane filament for preparing the hollow fiber membrane filament as described in any one of the preceding embodiments; the preparation method comprises the following steps:

[0012] quantitatively feeding the cavity-forming fluid, the first casting solution and the second casting solution to a spinneret, and extruding a nascent hollow fiber membrane filament; the spinneret comprises a first channel, a second channel and a third channel which are sequentially nested from inside to outside, the cavity-forming fluid is fed to the first channel, the first casting solution is fed to the second channel, and the second casting solution is fed to the third channel; the first casting solution and the second casting solution both comprise a polyolefin and a diluent, and the solubility of the diluent in the first casting solution to the polyolefin is less than the solubility of the diluent in the second casting solution to the polyolefin;

[0013] subjecting the nascent hollow fiber membrane filament to an atmosphere bath and a coagulation bath in sequence, and coagulating and forming;

[0014] immersing the coagulated and formed nascent hollow fiber membrane filament into an extractant to remove the diluent and form membrane pores; and,

[0015] subjecting the nascent hollow fiber membrane filament with formed membrane pores to a heat treatment.

[0016] Optionally, at the same temperature, the radius Ri1 of the Hansen sphere of the diluent in the first casting solution to the polyolefin is 4.5-10, and the radius Ri2 of the Hansen sphere of the diluent in the second casting solution to the polyolefin is 2.5-4.

[0017] Optionally, the diluent in the first casting solution comprises a first solvent and a second solvent, or the diluent in the first casting solution comprises a first solvent and a third solvent.

[0018] the diluent in the second casting solution comprises a first solvent and a second solvent, or the diluent in the second casting solution comprises a first solvent and a third solvent;

[0019] the solubility of the first solvent, the second solvent and the third solvent to the polyolefin is sequentially weakened, and the mass percentage of the first solvent in the diluent in the first casting solution is less than the mass percentage of the first solvent in the diluent in the second casting solution.

[0020] Optionally, the first solvent comprises at least one of dioctyl phthalate, dioctyl oxalate, dioctyl sebacate, isopropyl myristate, the second solvent comprises at least one of dibutyl phthalate, dibutyl adipate, dibutyl sebacate, diethyl adipate, glycerol triacetate, and the third solvent comprises at least one of castor oil, sesame oil, and soybean oil.

[0021] Optionally, the diluent of the first casting solution comprises the first solvent and the second solvent, and the mass percentage of the first solvent is less than or equal to 50%; or the diluent of the first casting solution comprises the first solvent and the third solvent, and the mass percentage of the first solvent is less than or equal to 80%.

[0022] Optionally, the diluent of the second casting solution comprises the first solvent and the second solvent, and the mass percentage of the first solvent is greater than or equal to 50%; or the diluent of the second casting solution comprises the first solvent and the third solvent, and the mass percentage of the first solvent is greater than or equal to 80%.

[0023] Optionally, the temperature of the atmosphere bath is 150-230 DEG C, and the length of the atmosphere bath is 5-30 cm.

[0024] Compared with the prior art, the hollow fiber membrane filament and the preparation method thereof, the oxygenation membrane and the oxygenation assembly have the following advantages:

[0025] The aforementioned hollow fiber membrane filament comprises a first support layer, a second support layer and a skin layer arranged from inside to outside along the radial direction thereof, the first support layer and the second support layer are both porous structures, and the pore size of the pores in the first support layer is greater than the pore size of the pores in the second support layer, so that the first support layer and the second support layer have a large pore size difference, which is beneficial to the transmission of oxygen from the inner cavity of the hollow fiber membrane filament to the outside, improves the oxygen leakage coefficient, and thus the oxygenation membrane prepared from the hollow fiber membrane filament has good gas exchange performance. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings are used to better understand the present application, and do not constitute undue limitations on the present application. Among them:

[0027] Figure 1 is a structure schematic diagram of a spinneret provided by the present application according to an embodiment;

[0028] Figure 2 is a scanning electron microscope photo of the cross section of the hollow fiber membrane filament prepared in Embodiment One of the present application;

[0029] Figure 3is a partial scanning electron microscope photo of the first support layer of the hollow fiber membrane filament prepared in Embodiment One of the present application;

[0030] Figure 4 is a partial scanning electron microscope photo of the second support layer of the hollow fiber membrane filament prepared in Embodiment One of the present application.

[0031] [The following is a description of reference numerals]:

[0032] 11 - first support layer, 12 - second support layer, 13 - skin layer;

[0033] 20 - spinneret, 21 - first channel, 22 - second channel, 23 - third channel;

[0034] 30 - atmosphere bath;

[0035] 40 - heating module. DETAILED DESCRIPTION

[0036] Other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied in other different specific embodiments, and various modifications or changes can be made to the details in the present specification based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the present embodiment only schematically illustrate the basic concepts of the present application, and thus the drawings only show the components related to the present application rather than the number, shape and size of the components when actually implemented. The actual implementation of each component can be randomly changed in terms of type, number and proportion, and the layout type of the components can also be more complex.

[0037] In addition, each embodiment of the following description has one or more technical features, but this does not mean that the user must simultaneously implement all technical features in any embodiment, or can only separately implement one or all technical features in different embodiments. In other words, under the premise of implementation, those skilled in the art can selectively implement part or all of the technical features in any embodiment, or selectively implement a combination of part or all of the technical features in multiple embodiments, thereby increasing the flexibility of the implementation of the present application.

[0038] In order to make the purpose, advantages and characteristics of the present application more clear, the present application will be further described in detail below in combination with the drawings. It should be noted that the drawings all adopt a very simplified form and use non-precise proportions, only to facilitate and clearly assist the purpose of explaining the embodiments of the present application. The same or similar reference numerals in the drawings represent the same or similar parts.

[0039] The core idea of ​​this invention is to provide a hollow fiber membrane filament, such as... Figures 2 to 4 As shown, the hollow fiber membrane includes a first support layer 11, a second support layer 12, and a skin layer 13 arranged radially from the inside to the outside. Both the first support layer 11 and the second support layer 12 are porous structures, with the pore size in the first support layer 11 being larger than that in the second support layer 12. The skin layer 13 is a dense structure. The hollow fiber membrane can be used to manufacture an oxygenation membrane, allowing oxygen to be transported from the inner cavity of the hollow fiber membrane and pass through the first support layer 11, the second support layer 12, and the skin layer 13 to exchange gases with the blood located outside the oxygenation membrane, thereby regulating the oxygen content in the blood. The hollow fiber membrane provided in this embodiment of the invention has an inner layer with a first support layer 11 having a larger pore size and a second support layer 12 having a smaller pore size, resulting in a large pore size difference from the inside to the outside of the inner layer. This allows more oxygen to pass through the membrane layer and enter the blood, giving the hollow fiber membrane a better oxygen permeability coefficient. The presence of the skin layer 13 and the second support layer 12 avoids increasing the plasma leakage rate and ensures the anti-plasma leakage time of the hollow fiber membrane. Thus, while ensuring the anti-plasma leakage time of the oxygenation membrane, the gas permeability coefficient of the oxygenation membrane is relatively high. In addition, since the skin layer 13 is composed of a polymer with good hydrophobicity and has a dense structure, it exhibits good hydrophobicity, preventing blood deposition and thrombus formation. This further enables the hollow fiber membrane provided in this embodiment of the invention to have a longer anti-plasma leakage time while achieving a better gas permeability coefficient.

[0040] Preferably, the gas flux of the hollow fiber membrane filament is 1.8 ml / (min·cm). 2 ·bar)~4ml / (min·cm 2 (bar). Furthermore, depending on the specific preparation conditions, the thickness of the first support layer 11 is 70µm to 120µm, the thickness of the second support layer 12 is 10µm to 40µm, and the thickness of the skin layer 13 is 0.08µm to 1µm. It is understood that pores are also formed on the skin layer 13, but the pore size on the skin layer 13 is much smaller than the pore size of the pores in the second support layer 12, to allow gas exchange between oxygen and carbon dioxide in the blood, but to prevent plasma leakage. The pore size on the skin layer 13 is 20nm to 200nm.

[0041] The hollow fiber membrane filaments are typically woven to form the oxygenated membrane. Preferably, the hollow fiber membrane filaments have a tensile strength of 1.0N to 2.3N and an elongation at break of 100% to 300%, which enables the hollow fiber membrane filaments to resist tensile deformation and reduce breakage during the weaving process.

[0042] Further, the present application also provides an oxygenation membrane made of the hollow fiber membrane filament, and an oxygenation assembly comprising the oxygenation membrane.

[0043] Further, the present application also provides a preparation method based on thermally induced phase separation method to prepare the aforementioned hollow fiber membrane filament. The preparation method comprises the following steps:

[0044] Firstly, the cavity-forming fluid, the first casting solution and the second casting solution are quantitatively fed to the spinneret 20 (as Figure 2 indicated) and extruded to obtain the nascent hollow fiber membrane filament.

[0045] Then, the nascent hollow fiber membrane filament is passed through the atmosphere bath 30 (as Figure 2 indicated).

[0046] Then, the nascent hollow fiber membrane filament is passed through the coagulation bath (not shown in the figure).

[0047] Subsequently, the nascent hollow fiber membrane filament is passed through the extractant tank (not shown in the figure).

[0048] Finally, the nascent hollow fiber membrane filament is heat treated to be shaped, and the hollow fiber membrane filament is obtained.

[0049] As Figure 2 shown, the spinneret 20 is a three-channel spinneret, which comprises a first channel 21, a second channel 22 and a third channel 23 arranged in a nested manner from inside to outside. The cavity-forming fluid is fed to the first channel 21, the first casting solution is fed to the second channel 22, and the second casting solution is fed to the third channel 23. The first casting solution and the second casting solution are extruded at the spinneret 20 to form a circular ring-shaped liquid flow, wherein the first casting solution is located at the inside and is used to finally form the first support layer 11, and the second casting solution is located at the outside and is used to finally form the second support layer 12 and the skin layer 13.

[0050] Here, the first casting solution and the second casting solution each include a polyolefin and a diluent. The polyolefin in the first casting solution and the second casting solution is the same in kind, including but not limited to poly(4-methyl-1-pentene). The diluent in the first casting solution and the second casting solution is the same in kind but different in ratio, or different in kind but the same in ratio, and the solubility of the diluent in the first casting solution to the polyolefin is less than the solubility of the diluent in the second casting solution to the polyolefin. This is because the weaker the solubility of the diluent to the polyolefin within a given solubility range, the larger the pore size of the pores formed on the support layer when the diluent is extracted and pores are formed. Thus, the hollow fiber membrane prepared by this method can form a first support layer 11 and a second support layer 12, and the pore size of the pores on the first support layer 11 is larger than the pore size of the pores on the second support layer 12.

[0051] Preferably, the radius Ri1 of the Hansen sphere of the diluent in the first casting solution to the polyolefin is 4.5-10, and the radius Ri2 of the Hansen sphere of the diluent in the second casting solution to the polyolefin is 2.5-4. Those skilled in the art know that the radius of the Hansen sphere characterizes the solubility of the polyolefin in the corresponding diluent. In addition, those skilled in the art can understand that when the corresponding diluent can completely dissolve the polyolefin, the casting solution is a homogeneous solution, and when the diluent cannot completely dissolve the polyolefin, the corresponding casting solution can be a uniformly dispersed suspension.

[0052] The relationship between the mass fraction of the polyolefin in the first casting solution and the mass fraction of the polyolefin in the second casting solution in the preparation method is not particularly limited, and the mass fraction of the polyolefin in the first casting solution can be greater than, less than, or equal to the mass fraction of the polyolefin in the second casting solution.

[0053] Alternatively, the diluent in the first casting solution includes a first solvent and a second solvent, or the diluent in the first casting solution includes a first solvent and a third solvent. In addition, the diluent in the second casting solution includes a first solvent and a second solvent, or the diluent in the second casting solution includes a first solvent and a third solvent. The solubility of the first solvent, the second solvent, and the third solvent to the polymer decreases in turn, and the mass percentage of the first solvent in the diluent of the first casting solution is less than the mass percentage of the first solvent in the diluent of the second casting solution.

[0054] Optionally, the first solvent includes at least one of dioctyl phthalate, dioctyl oxalate, dioctyl sebacate, isopropyl myristate. The second solvent includes at least one of dibutyl phthalate, dibutyl adipate, dibutyl sebacate, diethyl adipate, glyceryl triacetate. The third solvent includes at least one of castor oil, sesame oil, soybean oil.

[0055] When the diluent of the first casting solution includes the first solvent and the second solvent, the mass percentage of the first solvent is less than or equal to 50%.

[0056] When the diluent of the first casting solution includes the first solvent and the third solvent, the mass percentage of the first solvent is less than or equal to 80%.

[0057] When the diluent of the second casting solution includes the first solvent and the second solvent, the mass percentage of the first solvent is greater than or equal to 50%.

[0058] When the diluent of the second casting solution includes the first solvent and the third solvent, the mass percentage of the first solvent is greater than or equal to 80%.

[0059] Further, the medium of the atmosphere bath is nitrogen, inert gas, carbon dioxide or air. The temperature of the atmosphere bath is less than the temperature at the outlet of the spinneret 20 and greater than or equal to the initial temperature of the coagulation bath. Here, the first casting solution and the second casting solution are extruded by an extruder to supply the spinneret, and the temperature at the outlet of the spinneret 20 can be considered as the extrusion temperature of the first casting solution and the second casting solution, which can be 230-235°C, and can be adjusted according to the composition of the first casting solution and the second casting solution, as long as the first casting solution and the second casting solution can be extruded. The initial temperature of the coagulation bath refers to the temperature of the coagulation medium contained in the coagulation bath before the nascent fiber enters the coagulation bath. The specific temperature of the atmosphere bath can be selected in the range of 150-230°C. It can be understood that the atmosphere bath 30 can be provided with a heating module 40 to heat the medium in the atmosphere bath 30, so that the temperature of the medium is higher than normal temperature, and the temperature of the atmosphere bath is higher than normal temperature. During the atmosphere bath process, the surface layer of the nascent hollow fiber membrane is in contact with air, the casting solution is extruded from the spinneret 20, and the change of the environmental heat causes the polymer to gather to the outer layer. A higher temperature ensures the persistence of the polymer gathering to the outer layer, and the diluent on the surface of the outer layer is heated to produce a small part of volatilization, so that the content of the diluent on the surface of the outer layer is reduced and the content of the polyolefin is increased. Thus, in the coagulation bath stage, the nascent fiber is cooled and can form a dense skin layer 13. Alternatively, the length of the atmosphere bath is 5-30 cm (i.e. the length of the atmosphere bath 30 is 5-30 cm).

[0060] Alternatively, the embodiment of the present application also provides another preparation method based on the thermally induced phase separation method to prepare the hollow fiber membrane. The steps of the another preparation method are basically the same as those of the aforementioned preparation method, and the difference is only that the solubility of the diluent in the two casting solutions to the polyolefin is equivalent, and the mass percentage of the polyolefin in the first casting solution is less than that in the second casting solution. Because generally, the greater the mass percentage of the polyolefin in the casting solution, the smaller the pore size of the pores formed after the support layer is extracted. It should be noted that "the solubility of the diluent in the two casting solutions to the polyolefin is equivalent" means that the solubility of the diluent in the first casting solution to the polyolefin is equal or basically equal to that of the diluent in the second casting solution to the polyolefin, for example, the same diluent is used in the two casting solutions.

[0061] Next, the preparation method of the hollow fiber membrane and the performance of the hollow fiber membrane prepared by the method will be further described in conjunction with specific embodiments. The polyolefin in all the following examples and comparative examples is poly(4-methyl-1-pentene).

[0062] <Example 1>

[0063] In this embodiment, the first casting solution contains 40% polyolefin by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, wherein the mass fraction of dioctyl phthalate is 40% and the mass fraction of dibutyl phthalate is 60%. The second casting solution contains 40% polyolefin by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, wherein the mass fraction of dioctyl phthalate is 80% and the mass fraction of dibutyl phthalate is 20%. The temperature of the atmosphere bath is 210°C, and the length of the atmosphere bath is 15 cm.

[0064] Scanning electron microscope (SEM) images of the cross-section of the hollow fiber membrane filaments prepared in this embodiment are shown below. Figures 2 to 4 As shown. By Figures 2 to 4 It can be clearly seen that large holes are formed on the first support layer 11, the structure of the second support layer 12 is similar to a honeycomb, and the diameter of the holes on the second support layer 12 is smaller than the diameter of the holes on the first support layer 11.

[0065] The performance parameters of the hollow fiber membrane filaments prepared in this embodiment are shown in Table 1. The oxygen flux, carbon dioxide flux, tensile strength, and plasma leakage resistance time were all obtained using existing conventional testing methods.

[0066] <Example 2>

[0067] In this embodiment, the first casting solution contains 40% polyolefin by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, wherein the mass fraction of dioctyl phthalate is 40% and the mass fraction of dibutyl phthalate is 60%. The second casting solution contains 40% polyolefin by mass, and the diluent is a mixture of dioctyl phthalate and castor oil, wherein the mass fraction of dioctyl phthalate is 95% and the mass fraction of castor oil is 5%. The temperature of the atmosphere bath is 210°C, and the length of the atmosphere bath is 15 cm. The performance parameters of the hollow fiber membrane filaments prepared in this embodiment are shown in Table 1.

[0068] <Example 3>

[0069] In this example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and castor oil, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of castor oil is 20%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the air bath is 210°C, and the length of the air bath is 15 cm. The performance parameters of the hollow fiber membrane prepared in this example are shown in Table 1.

[0070] <Example Four>

[0071] In this example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and castor oil, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of castor oil is 20%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and castor oil, and in the diluent, the mass fraction of dioctyl phthalate is 95%, and the mass fraction of castor oil is 5%. The temperature of the air bath is 210°C, and the length of the air bath is 15 cm. The performance parameters of the hollow fiber membrane prepared in this example are shown in Table 1.

[0072] <Example Five>

[0073] In this example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the air bath is 150°C, and the length of the air bath is 15 cm. The performance parameters of the hollow fiber membrane prepared in this example are shown in Table 1.

[0074] <Example Six>

[0075] In this example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the air bath is 230°C, and the length of the air bath is 15 cm. The performance parameters of the hollow fiber membrane prepared in this example are shown in Table 1.

[0076] <Example Seven>

[0077] In this example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the air bath is 210°C, and the length of the air bath is 5 cm. The performance parameters of the hollow fiber membrane prepared in this example are shown in Table 1.

[0078] <Example Eight>

[0079] In this example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the air bath is 210°C, and the length of the air bath is 30 cm. The performance parameters of the hollow fiber membrane prepared in this example are shown in Table 1.

[0080] <Comparative Example One>

[0081] In this comparative example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The temperature of the air bath is 210°C, and the length of the air bath is 15 cm. The performance parameters of the hollow fiber membrane filaments prepared in this comparative example are shown in Table 1.

[0082] <Comparative Example Two>

[0083] In this comparative example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the air bath is 210°C, and the length of the air bath is 15 cm. The performance parameters of the hollow fiber membrane filaments prepared in this comparative example are shown in Table 1.

[0084] <Comparative Example Three>

[0085] In this comparative example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the air bath is 20°C, and the length of the air bath is 15 cm. The performance parameters of the hollow fiber membrane filaments prepared in this comparative example are shown in Table 1.

[0086] <Comparative Example Four>

[0087] In the present comparative example, the first casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 40%, and the mass fraction of dibutyl phthalate is 60%. The second casting solution has a polyolefin content of 40% by mass, and the diluent is a mixture of dioctyl phthalate and dibutyl phthalate, and in the diluent, the mass fraction of dioctyl phthalate is 80%, and the mass fraction of dibutyl phthalate is 20%. The temperature of the atmosphere bath is 210°C, and the length of the atmosphere bath is 1 cm. The performance parameters of the hollow fiber membrane filaments prepared in the present comparative example are shown in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] Comparing Example 1 and Comparative Example 1, the solubility of the diluent of the first casting solution used in Example 1 to the polymer is less than that of the diluent of the second casting solution, while in Comparative Example 1, the diluent formulations of the two casting solutions are the same, and are the same as the diluent of the first casting solution in Example 1. Therefore, in Comparative Example 1, the solubility of the two diluents to the polymer is also the same, and the size of the pores in the first support layer and the second support layer of the hollow fiber membrane filaments prepared is the same, and is comparable to the size of the pores in the first support layer of Example 1, and is larger than the size of the pores in the second support layer of Example 1. This results in the gas flux of the hollow fiber membrane filaments prepared in Comparative Example 1 being slightly larger than that of the hollow fiber membrane filaments prepared in Example 1, but the plasma leakage resistance performance is poorer.

[0092] Comparing Example 1 and Comparative Example 2, the diluents in the first casting solution and the second casting solution of Comparative Example 2 are the same, and are the same as the diluent of the second casting solution in Example 1, and have a stronger solubility to the polymer. Therefore, the hollow fiber membrane filaments prepared in Comparative Example 2 have smaller pores in the first support layer and the second support layer, resulting in a smaller overall gas flux of the hollow fiber membrane filaments.

[0093] Comparing Example 1 and Comparative Example 3, the temperature of the atmosphere bath in Comparative Example 3 is 20°C, and since the temperature of the atmosphere bath is lower, when the first casting solution and the second casting solution in Comparative Example 3 are extruded and enter the atmosphere bath, the time for the polymer to aggregate to the outer layer due to the temperature change is greatly shortened, so that the casting solution is quickly solidified after extrusion, resulting in a decrease in the thickness of the skin layer, and further resulting in poor plasma leakage resistance of the hollow fiber membrane filaments prepared in Comparative Example 3.

[0094] Comparing Comparative Example 1 with Comparative Example 4, the length of the air bath in Comparative Example 4 is only 1 cm. When the first casting solution and the second casting solution of Comparative Example 4 are extruded and enter the air bath, the time for the polymer to be gathered to the outer layer due to the temperature change is greatly shortened because the length of the air bath is shorter. Therefore, the casting solution is quickly solidified after being extruded, which is not conducive to the gathering of the polymer on the surface layer, resulting in a small thickness of the skin layer, and further resulting in a poor plasma leakage resistance of the hollow fiber membrane prepared in Comparative Example 4.

[0095] Comparing Comparative Example 1 with Example 2, although the components and contents of the diluent of the second casting solution in the two examples are different, the gas fluxes of the hollow fiber membranes prepared in the two examples are similar, because the solubility of the two examples for the polymer is similar by adjusting the components and contents of the diluent of the second casting solution.

[0096] Comparing Comparative Example 1 with Example 3, although the components and contents of the diluent of the first casting solution in the two examples are different, the gas fluxes of the hollow fiber membranes prepared in the two examples are similar, because the solubility of the two examples for the polymer is similar by adjusting the components and contents of the diluent of the first casting solution.

[0097] Comparing Comparative Example 3 with Example 4, although the components and contents of the diluent of the second casting solution in the two examples are different, the gas fluxes of the hollow fiber membranes prepared in the two examples are similar, because the solubility of the two examples for the polymer is similar by adjusting the components and contents of the diluent of the second casting solution. In addition, because the volatility of castor oil is higher than that of dioctyl phthalate and dibutyl phthalate, the diluent of the second casting solution in Example 4 volatilizes more strongly in the process of the air bath, which is conducive to the gathering of the polymer on the surface layer to form a skin layer with a greater thickness.

[0098] Comparing Comparative Example 1, Example 5 and Example 6, the temperature of the air bath in Example 6 is the highest, the temperature of the air bath in Example 1 is the second, and the temperature of the air bath in Example 5 is the lowest. After the casting solution is extruded from the die, the temperature decreases, and part of the diluent on the outermost layer will volatilize at the moment of extrusion. With the decrease of temperature, the phase separation gradually begins to occur. Because the temperature of the air bath in Example 6 is close to the temperature of the die, at this temperature, the phase separation is just beginning, and the temperature change just overcomes a part of the energy barrier for forming a new phase, and then enters the coagulation bath for rapid solidification. Therefore, at this temperature, it is considered that the phase separation is limited, so the surface dense layer is relatively thinner.

[0099] Comparing comparative example 1, example 7 and example 8, the length of the atmosphere bath of example 8 is the longest, the length of the atmosphere bath of example 1 is the second longest, and the length of the atmosphere bath of example 7 is the shortest. Under the same conditions, the longer the length of the atmosphere bath, the more complete the volatilization of the diluent, the more the polymer migrates to the outer layer, which is more conducive to forming a skin layer with a larger thickness and improving the plasma leakage resistance of the hollow fiber membrane.

[0100] While the application has been disclosed by reference to the above description, it is understood that changes and modifications can be made to the application without departing from the spirit and scope thereof. It is therefore intended that the application not be limited to the exact description as set forth above, but that changes and modifications be included within the spirit and scope of the application.

Claims

1. A hollow fiber membrane filament, characterized by, The hollow fiber membrane filament comprises a first support layer, a second support layer and a skin layer arranged radially from inside to outside, the first support layer and the second support layer are both porous structures, and the pore size of the pores in the first support layer is greater than the pore size of the pores in the second support layer; The hollow fiber membrane filament is prepared by the following method: The cavity-forming fluid, the first casting solution and the second casting solution are quantitatively fed to the spinneret, and the nascent hollow fiber membrane filament is extruded; the spinneret comprises a first channel, a second channel and a third channel which are sequentially nested from inside to outside, the cavity-forming fluid is fed to the first channel, the first casting solution is fed to the second channel, and the second casting solution is fed to the third channel; The first casting solution and the second casting solution both comprise a polyolefin and a diluent, and the solubility of the diluent in the first casting solution to the polyolefin is less than the solubility of the diluent in the second casting solution to the polyolefin; The nascent hollow fiber membrane filament is sequentially passed through an atmosphere bath and a coagulation bath, and is coagulated and formed; the temperature of the atmosphere bath is 150-230°C; The coagulated and formed nascent hollow fiber membrane filament is immersed in an extractant to remove the diluent and form membrane pores; and The nascent hollow fiber membrane filament with formed membrane pores is subjected to heat treatment.

2. The hollow fiber membrane filament of claim 1, wherein, The gas flux of the hollow fiber membrane filaments is 1.8 ml / (min cm 2 ·bar) to 4 ml / (min cm 2 ·bar).

3. The hollow fiber membrane filament of claim 1 or 2, wherein, The thickness of the first support layer is 70-120μm, the thickness of the second support layer is 10-40μm, and the thickness of the skin layer is 0.08-1μm.

4. The hollow fiber membrane of claim 1, wherein, The tensile strength of the hollow fiber membrane filament is 1.0-2.3N, and the elongation at break is 100-300%.

5. An oxygenation membrane characterized by, The oxygenation membrane is made of the hollow fiber membrane filament according to any one of claims 1-4.

6. An oxygenation assembly, characterized by, The oxygenation assembly comprises the oxygenation membrane according to claim 5.

7. A method for producing a hollow fiber membrane filament for producing a hollow fiber membrane filament according to any one of claims 1 to 4, characterized in that, The preparation method comprises the following steps: The cavity-forming fluid, the first casting solution and the second casting solution are quantitatively fed to the spinneret, and the nascent hollow fiber membrane filament is extruded; the spinneret comprises a first channel, a second channel and a third channel which are sequentially nested from inside to outside, the cavity-forming fluid is fed to the first channel, the first casting solution is fed to the second channel, and the second casting solution is fed to the third channel; The first casting solution and the second casting solution both comprise a polyolefin and a diluent, and the solubility of the diluent in the first casting solution to the polyolefin is less than the solubility of the diluent in the second casting solution to the polyolefin; The nascent hollow fiber membrane filament is sequentially passed through an atmosphere bath and a coagulation bath, and is coagulated and formed; the temperature of the atmosphere bath is 150-230°C; The coagulated and formed nascent hollow fiber membrane filament is immersed in an extractant to remove the diluent and form membrane pores; and The nascent hollow fiber membrane filament with formed membrane pores is subjected to heat treatment.

8. The method of producing a hollow fiber membrane filament according to claim 7, characterized by, At the same temperature, the radius Ri1 of the Hansen sphere of the diluent in the first casting solution to the polyolefin is 4.5-10, and the radius Ri2 of the Hansen sphere of the diluent in the second casting solution to the polyolefin is 2.5-4.

9. The method of producing a hollow fiber membrane filament according to claim 7 or 8, characterized by, The diluent in the first casting solution comprises a first solvent and a second solvent, or the diluent in the first casting solution comprises a first solvent and a third solvent; The diluent in the second casting solution comprises a first solvent and a second solvent, or the diluent in the second casting solution comprises a first solvent and a third solvent; The solubility of the first solvent, the second solvent and the third solvent for the polyolefin decreases in turn, and the mass percentage of the first solvent in the diluent of the first casting solution is less than that in the diluent of the second casting solution.

10. The method of producing a hollow fiber membrane filament according to claim 9, characterized by, The first solvent comprises at least one of dioctyl phthalate, dioctyl oxalate, dioctyl sebacate, isopropyl myristate, the second solvent comprises at least one of dibutyl phthalate, dibutyl adipate, dibutyl sebacate, diethyl adipate, glycerol triacetate, and the third solvent comprises at least one of castor oil, sesame oil, soybean oil.

11. The method of producing a hollow fiber membrane filament according to claim 10, characterized by, The diluent of the first casting solution comprises the first solvent and the second solvent, and the mass percentage of the first solvent is less than or equal to 50%; or the diluent of the first casting solution comprises the first solvent and the third solvent, and the mass percentage of the first solvent is less than or equal to 80%.

12. The method of producing a hollow fiber membrane filament according to claim 10, characterized by, The diluent of the second casting solution comprises the first solvent and the second solvent, and the mass percentage of the first solvent is greater than or equal to 50%; or the diluent of the second casting solution comprises the first solvent and the third solvent, and the mass percentage of the first solvent is greater than or equal to 80%.

13. The method of producing a hollow fiber membrane filament according to claim 7, characterized by, The length of the atmosphere bath is 5cm-30cm.

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