Ultrafiltration membrane for separating virus and protein

Abstract

The utility model discloses an ultrafiltration membrane for separating viruses and proteins, and belongs to the technical field of virus-removing flat membranes and virus-removing filters. Comprising a spongy macroporous layer, a non-woven fabric layer tightly connected with the spongy macroporous layer, and a spongy microporous layer connected with the non-woven fabric layer, the spongy macroporous layer completely permeates into the non-woven fabric layer, and the spongy microporous layer partially permeates into the non-woven fabric layer. The structure is integrally formed, large-scale preparation can be achieved, meanwhile, film material layers are tightly combined, the falling risk is avoided, the enhanced structure strength is high, and the risks of damage and leakage in the assembly preparation process are greatly reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of virus removal flat sheet membrane and virus removal filter, and relates to a kind of ultrafiltration membrane for separating virus and protein. BACKGROUND

[0002] Ultrafiltration membrane is the porous separation material that one layer of extremely thin skin layer and relatively thick sponge-like or finger-like pore layer that support function are separated, and cutting molecular weight is from several hundred to several million Dalton, and the pore size is 1-100nm. The early ultrafiltration membrane is cellulose acetate material, with the development of technology, polysulfone, polyolefin, fluorine-containing, polyamide and inorganic membrane material are also developed for preparing ultrafiltration membrane. Ultrafiltration membrane is mainly used for solution purification, separation and concentration, especially in drinking water treatment, wastewater advanced treatment, chemical material separation, wine beverage concentration and biopharmaceutical field, and has wide application in industrial field.

[0003] In biopharmaceutical process, protein-based therapeutic drugs based on cell expression exist the risk of being contaminated by endogenous and exogenous viruses. Once virus contamination occurs, it will affect the safety of therapeutic products and cause harm to patients. The application of ultrafiltration membrane that only screens and filters viruses through physical means can achieve efficient removal of non-enveloped viruses, without any impact on proteins. At present, there are two kinds of ultrafiltration membranes with virus removal function on the market. One is the ultrafiltration membrane that intercepts viruses through small pores in the skin layer. Although this ultrafiltration membrane has certain virus retention capacity, since the size of common small viruses is about 25nm, and the size of target protein and its aggregates is about 15nm, the use of ultrafiltration membrane that only separates through skin layer has the problems of poor separation precision, low permeation flux and protein yield, and there is a huge risk of virus penetration, which is difficult to use. The other is the ultrafiltration membrane that intercepts viruses through small pores connected between layers. The ultrafiltration membrane with this structure has extremely fine capillary pores and large void pores, which has the interception effect on viruses while allowing proteins to pass through, has high protein yield, and realizes efficient separation of viruses and proteins.

[0004] The patent document CN1759924B of Millipore Corporation discloses a multi-layer composite membrane with at least one ultrafiltration layer, which includes an asymmetric ultrafiltration membrane layer with skin connected with a second asymmetric ultrafiltration membrane layer, connected by pore size with gradient distribution, and the gradient distribution is from the pore size of the second ultrafiltration layer near the connection to the pore size of the first ultrafiltration layer near the connection. The ultrafiltration membrane with this structure can realize the use of removing virus particles in solution containing artificial protein.

[0005] A virus-removing composite membrane is disclosed in patent document CN117942776A of Hangzhou Kebaiter Filter Material Co., Ltd., which has a porous base layer formed of a first polymer and a separation layer formed of a second polymer, and a binding area formed on a side of the porous base layer close to the separation layer and a side of the separation layer close to the porous base layer, with the pores in the binding area being interconnected. The composite membrane has improved membrane flux and separation layer binding strength, and maintains other performances without significant attenuation, meeting the actual virus-removing application requirements.

[0006] A virus composite filtration membrane is disclosed in patent document CN112892229A of Guangzhou Institute of Advanced Technology, Chinese Academy of Sciences, which has a three-stage membrane pore structure of a pre-filtering membrane, an intermediate support layer and a small-pore ultrafiltration membrane, with high separation efficiency and fast virus filtration.

[0007] The above-reported ultrafiltration membranes are all suitable for separating viruses from proteins in biopharmaceutical processes, but all have problems such as complex preparation process control method, low composite structure binding force, complicated preparation process, and difficulty in realizing continuous production. SUMMARY

[0008] The utility model discloses a kind of ultrafiltration membranes for separating virus and protein for prior art problem.

[0009] An ultrafiltration membrane for separating virus and protein, comprising a sponge-like macroporous layer, a non-woven fabric layer closely connected to the sponge-like macroporous layer, and a sponge-like microporous layer connected to the non-woven fabric. The sponge-like macroporous layer is completely permeated into the non-woven fabric layer, and the sponge-like microporous layer is partially permeated into the non-woven fabric layer.

[0010] The outer surface of the sponge-like macroporous layer is an upstream face, with a surface pore size of 50-1500 nm. The outer surface of the sponge-like microporous layer is a downstream face, with a surface pore size of 15-50 nm. The overall pore size of the ultrafiltration membrane is 20-25 nm.

[0011] The pore structure of the sponge-like macroporous layer is stacked by interconnected grid-like pores, and the pore structure of the sponge-like microporous layer is composed of tortuous communication channels with gullies, representing pore structures formed by different film-forming mechanisms, respectively.

[0012] The thickness of the sponge-like macroporous layer is 120 μm, the thickness of the sponge-like microporous layer is 40 μm, and the overall thickness of the ultrafiltration membrane is 160 μm. The materials of the sponge-like macroporous layer and the sponge-like microporous layer are both polyether sulfone, and the material of the non-woven fabric layer is polypropylene or polyphenylene sulfide.

[0013] An ultrafiltration membrane for separating virus and protein can be obtained by the following steps:

[0014] Step P1, prepare casting solution L for forming sponge-like macroporous layer and casting solution S for forming sponge-like microporous layer respectively, coat casting solution L on moving carrier to form sponge-like macroporous layer, tightly adhere non-woven fabric layer on the liquid film of sponge-like macroporous layer before the sponge-like macroporous layer is solidified, then coat casting solution S on the non-woven fabric layer to form sponge-like microporous layer.

[0015] Step P2, after the carrier passes through an air section together with the double-layer liquid film formed by casting solution L and casting solution S and the tightly adhered non-woven fabric layer, immerse it in coagulation bath for phase separation forming, then after cleaning and drying, obtain the ultrafiltration membrane.

[0016] Preferably, both casting solution L and S contain hydrophobic polymer, hydrophilic polymer, solvent and non-solvent, and the ratio is 15-25 parts: 3-10 parts: 15-50 parts: 40-70 parts.

[0017] Preferably, the hydrophobic polymer is polyether sulfone with a molecular weight of 48000-90000 Da; the hydrophilic polymer is one or more of sulfonated polysulfone, sulfonated polyether sulfone and polyvinyl pyrrolidone; the solvent is one or more of dimethylformamide, dimethylacetamide, N-methyl pyrrolidone, triethyl phosphate, dimethyl sulfoxide, caprolactam and propylene carbonate; and the non-solvent is one or more of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol and glycerol.

[0018] Preferably, the casting solution L is transferred to the moving carrier by means of doctor blade or slot die coating, wherein the moving carrier should not have the ability to combine with the casting solution L and be easily separated from the moving carrier after the casting solution L is formed, preferably a smooth polyethylene terephthalate film.

[0019] Preferably, the casting solution S is coated on the non-woven fabric layer by means of extrusion of pressurized slot die, wherein the non-woven fabric layer is pre-tightly adhered on the liquid film formed by the casting solution L before the casting solution S is coated.

[0020] Preferably, the air section is controlled by a constant temperature and humidity control system, and the control temperature range is 20-50℃ and the control humidity range is 20-80 RH%.

[0021] Preferably, the coagulation bath is pure water or a mixture of pure water and solvent, wherein the proportion of the solvent is not more than 10%.

[0022] The whole coating process is driven by mechanical device, and the casting solution L for forming sponge-like macroporous layer is first coated on the moving carrier, which is not mutually soluble with the casting solution and the casting solution only stays on the surface of the carrier without penetrating into the carrier, and after the casting solution is phase-separated and formed, it can be peeled off from the carrier, and the carrier is preferably a polyester film.

[0023] In one preferred embodiment, the sponge-like macroporous layer is a pore structure induced by heating the casting solution with a low critical solution temperature to above the critical temperature for a period of time to induce phase separation. The critical temperature of the sponge-like macroporous layer is preferably 30-60°C. The temperature required for partial phase separation of the sponge-like macroporous layer on the support is provided by a heatable support bottom roll, and therefore the thickness of the support needs to be controlled within a certain range to control the heat transfer rate, preferably the thickness is 0.036-0.25 mm.

[0024] There are various options for the manner of coating the casting solution onto the support, one preferred option is roll-liner blade coating, the thickness of the sponge-like macroporous layer can be controlled by adjusting the gap between the blade and the backing roll, preferably the gap is 130-300 μm. In addition, the coating can also be achieved by means of a pressurized die slot, etc. It is worth noting that the choice of coating method is related to the viscosity of the casting solution, when the viscosity of the casting solution is greater than 15000 cp, then it is no longer suitable for blade coating.

[0025] After the casting solution is coated onto the moving support, before the casting solution is phase separated into a form, the non-woven fabric is fitted onto the sponge-like macroporous layer by an additional lead roll and bottom roll forming an included angle, and then the other side of the non-woven fabric is coated with a casting solution that can form a sponge-like microporous layer. The role of the non-woven fabric layer is to connect the sponge-like macroporous layer and the sponge-like microporous layer, and to isolate the mutual mass transfer between the two layers, so that the phase separation processes of the two layers are carried out simultaneously and independently without interference. The material of the non-woven fabric layer is preferably polyethylene terephthalate or polypropylene, and can also be other macroporous materials consistent with the structure and function of the non-woven fabric layer. The thickness of the non-woven fabric layer is preferably 90-140 μm.

[0026] The preferred manner of coating the casting solution that can form a sponge-like microporous layer onto the non-woven fabric layer is die slot pressurized coating. A slot die includes a closed reservoir with a small cross-section outlet slot. The casting solution is fed into the reservoir at a constant rate by a feed pump at a certain pressure, and all the liquid entering the die is extruded from the outlet slot onto the non-woven fabric by pressure. The die is installed perpendicular to the non-woven fabric. The ultrafiltration membrane including the macroporous sponge layer and the microporous sponge layer is mostly a gradient pore structure or a gradually changing pore structure. Structures with a sudden change in pore size at an intermediate position often need to be achieved by a double-layer superposition. However, in the process of casting the double-layer membrane, there are problems in the control of the casting process from both the coating and the phase separation angles. Especially near the interface, the two layers of casting solution will inevitably merge due to the similar polarity of the solvents, making the control of the pore size more difficult. By separating the two layers of casting solution with a porous material, the phase change process of the two layers of casting solution is controlled separately, which can accurately control the pore size and pore structure of the double layer, thereby increasing the feasibility and operability of the ultrafiltration membrane preparation process.

[0027] After the coating is completed, the carrier and the double-layer casting solution pass through an air section with uniform and controllable temperature and humidity. The temperature of the air section is preferably set to 20-50 DEG C, and the relative humidity is preferably set to 20-80 RH%. The surface pore structure of the sponge-like small pore layer is opened by vapor-induced phase separation, that is, the wet air in the air section is used as a non-solvent to complete the partial phase separation process. The phase separation process is independent and is not disturbed by the phase separation process of the sponge-like large pore layer. In addition, since the sponge-like large pore layer is located inside the non-woven fabric layer at this time, and the sponge-like small pore layer is isolated from the air, the phase separation process of the sponge-like large pore layer is only related to the temperature.

[0028] After passing through the air section, the carrier and the double-layer membrane layer that has completed the partial phase separation are immersed in a gel bath to complete the entire phase separation process. The gel bath is preferably pure water or a mixture of pure water and a solvent, wherein the proportion of the solvent is not more than 10%. The gel bath temperature is preferably 30-60 DEG C. The process is controlled by a non-solvent. Since the intermediate layer of non-woven fabric is a porous material, the gel bath can enter the inside, at this time, the casting solution that has completed the partial phase separation process and the non-solvent are fully exchanged, the entire phase separation process is completed, and the sponge-like large pore layer and the sponge-like small pore layer are formed, respectively. Finally, the ultrafiltration membrane that has been completely phase-separated is peeled off from the carrier, and an additional cleaning step is performed to remove the residual solvent in the membrane, and then the final ultrafiltration membrane is obtained after drying.

[0029] The ultrafiltration membrane for separating viruses and proteins comprises a sponge-like large pore layer, a non-woven fabric layer closely connected to the sponge-like large pore layer, and a sponge-like small pore layer connected to the non-woven fabric. The sponge-like large pore layer completely penetrates into the non-woven fabric layer. The sponge-like small pore layer partially penetrates into the non-woven fabric layer. The structure is integrally formed, can realize large-scale preparation, and has no risk of falling off due to the close combination between the membrane material layers, has high enhanced structural strength, and greatly reduces the risk of damage and leakage in component preparation. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. As shown in the drawings:

[0031] Figure 1 It is a structural diagram of the coating process of the present application.

[0032] Figure 2This diagram shows the positional relationship between the carrier entering the air section after the coating process of this utility model is completed, and the double-layer casting liquid and non-woven fabric layer on it. Detailed Implementation

[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0034] Example 1: As Figure 1 , Figure 2 As shown, an ultrafiltration membrane for separating viruses and proteins is described. The membrane comprises a sponge-like macroporous layer, a nonwoven fabric layer tightly connected to the macroporous layer, and a sponge-like microporous layer connected to the nonwoven fabric. It is prepared by the following method: A casting solution L for forming the macroporous layer is first coated from a feed tank 11 onto a moving carrier 21, which is a polyethylene terephthalate film. The macroporous layer is a porous structure formed by heating the casting solution, which has a low critical dissolution temperature, to above the critical temperature and holding it for a period of time to induce phase separation. The pore size range is controlled by controlling the heating temperature and holding time. The critical temperature of the macroporous layer is 45°C. The carrier is driven onto a heated bottom roller 22 to provide the temperature required for phase separation; the carrier thickness is 0.1 mm.

[0035] The casting solution L is composed of polyethersulfone, sulfonated polyethersulfone, N-methylpyrrolidone and triethylene glycol with a molecular weight of 72,000 Da, in a ratio of 16.5 parts: 3.5 parts: 32 parts: 48 parts.

[0036] The casting solution L was coated onto the carrier using a roller-lined doctor blade, and the thickness of the coating was adjusted to 130 μm using a feeler gauge.

[0037] After the casting solution is applied to the moving carrier, and before the casting solution undergoes complete phase separation, the nonwoven fabric 31 is tightly bonded to the sponge-like macroporous layer via the wrap angle formed by the guide roller 41 and the heated bottom roller. Subsequently, the casting solution S, which forms a sponge-like microporous layer, is applied to the other side of the nonwoven fabric. The function of the nonwoven fabric layer is to connect the sponge-like macroporous layer and the sponge-like microporous layer, and to isolate the mass transfer between the two layers, allowing the phase separation processes of the two layers to occur simultaneously and independently without interference. The nonwoven fabric layer is made of polypropylene and has a thickness of 90 μm.

[0038] The casting solution S capable of forming the sponge-like small-pore layer is coated onto the non-woven fabric layer through a slot die 12. A slot die includes a closed reservoir with a small cross-section outlet slot. The casting solution is fed into the reservoir at a constant rate by a feed pump at a certain pressure, and all the liquid entering the die is extruded from the outlet slot to the non-woven fabric by the pressure. The slot is arranged perpendicular to the non-woven fabric.

[0039] After the coating is completed, the carrier and the double-layer casting solution pass through an air section with controllable temperature and humidity. The temperature in the air section is preferably set at 45°C, and the relative humidity is preferably set at 25 RH%. The surface pore structure of the sponge-like small-pore layer is opened by vapor-induced phase separation, that is, the wet air in the air section is used as a non-solvent to complete the partial phase separation process.

[0040] Reference Figure 2 The position relationship between the carrier and the double-layer casting solution and the non-woven fabric layer on the carrier after the coating process is completed and entering the air section is illustrated. The carrier is located at the innermost side, the sponge-like large-pore layer 13 is coated outside the carrier, the non-woven fabric layer is tightly combined with the sponge-like large-pore layer, and the sponge-like small-pore layer 14 is combined at the outermost side.

[0041] After passing through the air section, the carrier and the double-layer membrane layer that has completed the partial phase separation are immersed in a gel bath to complete the complete phase separation. The gel bath is pure water, and the temperature is 45°C.

[0042] After the complete phase separation, the ultrafiltration membrane is peeled off from the carrier, and then subjected to additional cleaning steps to remove the residual solvent in the membrane, and then subjected to drying to obtain the final ultrafiltration membrane.

[0043] As can be seen from the above description, the ultrafiltration membrane for separating viruses and proteins provided by the present application has a large-pore layer with a sponge-pore structure and a small-pore layer with a sponge-pore structure, which are connected to each other through the non-woven fabric layer, the phase separation processes do not interfere with each other, the connectivity between the pores is good, and the pore structure is complete. The sponge-like small-pore layer has the function of separating viruses and proteins, the sponge-like large-pore layer can effectively slow down the pollution speed of the sponge-like small-pore layer, improve the flux and the load, and meet the application of removing viruses from a protein solution.

[0044] Example 2: as shown in Figure 1 , Figure 2 A kind of ultrafiltration membrane for separating viruses and proteins, carrier is polyethylene terephthalate film, sponge-like large-pore layer is pore structure, casting solution is connected with mobile carrier, the wrap angle of non-woven fabric is connected on sponge-like large-pore layer, non-woven fabric is coated casting solution to form sponge-like small-pore layer on the other side, the material of non-woven fabric layer is modified polyethylene terephthalate, the thickness is 90 μm, carrier is located at the innermost side, sponge-like large-pore layer is coated outside the carrier, non-woven fabric layer is tightly connected with sponge-like large-pore layer, sponge-like small-pore layer is connected at the outermost side of carrier.

[0045] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An ultrafiltration membrane for separating viruses and proteins, characterized in that, The sponge-like large-pore layer, the non-woven fabric layer closely connected with the sponge-like large-pore layer, the sponge-like small-pore layer connected with the non-woven fabric layer, the sponge-like large-pore layer completely permeating into the non-woven fabric layer, and the sponge-like small-pore layer partially permeating into the non-woven fabric layer.

2. The ultrafiltration membrane for separating viruses and proteins according to claim 1, characterized by, The outer surface of the sponge-like large-pore layer is an upstream surface, and the surface pore size is 50-1500 nm; the outer surface of the sponge-like small-pore layer is a downstream surface, and the surface pore size is 15-50 nm; and the overall pore size of the ultrafiltration membrane is 20-25 nm.

3. The ultrafiltration membrane for separating viruses and proteins according to claim 1, characterized by, The pore structure of the sponge-like large-pore layer is stacked by grid-shaped pores in communication with each other, and the pore structure of the sponge-like small-pore layer is composed of tortuous communication channels with gullies, which represent the pore structures formed by different film-forming mechanisms, respectively.

4. The ultrafiltration membrane for separating viruses and proteins according to claim 1, characterized by, The thickness of the sponge-like large-pore layer is 120 μm, the thickness of the sponge-like small-pore layer is 40 μm, and the overall thickness of the ultrafiltration membrane is 160 μm.

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