A purification membrane for compound mannitol injection and its preparation method

Abstract

This invention relates to the field of purification membrane technology, specifically disclosing a purification membrane for compound mannitol injection and its preparation method. The purification membrane for compound mannitol injection provided by this invention solves the problems of unstable retention and rapid flux decline in existing filter membranes through its membrane layer and support layer. Specifically, the membrane layer uses polyethersulfone resin as a substrate, forming micropores under the action of a pore-forming agent to accurately retain various impurities and improve flux retention. The support layer adsorbs cationic impurities, reducing the burden on the membrane layer, preventing clogging, and extending its lifespan. The preparation method provided by this invention can construct a gradient pore size in the membrane layer, resulting in good filtration efficiency and structural stability of the purification membrane. Furthermore, the method is simple and controllable, suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of purification membrane technology, and specifically discloses a purification membrane for compound mannitol injection and its preparation method. Background Technology

[0002] Compound mannitol injection is a hypertonic dehydrating agent that primarily reduces tissue edema by increasing plasma osmotic pressure. Its formula mainly includes mannitol, sorbitol, glucose, and sodium chloride. During the production process of compound mannitol injection, insufficient purity of raw materials can lead to the presence of insoluble impurities. Additionally, due to excessively low production temperatures, mannitol and sorbitol are prone to forming microcrystalline particles with a diameter of 0.5 μm to 10 μm. If these insoluble impurities and crystals are not effectively removed, the efficacy and safety of compound mannitol injection will be affected.

[0003] Current technologies primarily employ polyethersulfone (PES) membranes and mixed cellulose ester membranes to remove insoluble impurities and microcrystals from compound mannitol injection solutions. However, existing PES membranes have a single pore size, leading to unstable retention when the particle size of insoluble impurities and microcrystals is large. Existing mixed cellulose ester membranes, after being soaked in solution for a period, experience unstable retention due to hyperosmotic swelling. Furthermore, both PES and mixed cellulose ester membranes have weak anti-clogging capabilities, resulting in a rapid decrease in membrane flux after continuous filtration. Therefore, addressing the issues of unstable membrane retention and rapid flux decline is of significant practical importance in the field of purification membrane technology. Summary of the Invention

[0004] To address the problems of unstable retention and rapid flux decline in existing filter membranes, this invention provides a purification membrane for compound mannitol injection and its preparation method. The purification membrane for compound mannitol injection comprises a membrane layer and a support layer. The membrane layer, under the action of a pore-forming agent, forms micropores, effectively improving impurity retention. Simultaneously, the carboxylated dextran on the surface of the support layer can adsorb cationic impurities in the injection through ion exchange, reducing the burden on the membrane layer and extending the service life of the purification membrane.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution.

[0006] The first aspect of the present invention provides a purification membrane for compound mannitol injection, comprising a membrane layer and a support layer, wherein the membrane layer comprises the following raw material components in parts by weight: 10 to 20 parts of polyethersulfone resin, 5 to 15 parts of pore-forming agent and 70 to 80 parts of polar aprotic organic solvent.

[0007] The support layer is a carboxylated dextran-grafted polyester nonwoven fabric.

[0008] The purification membrane for compound mannitol injection provided by this invention, through the synergistic effect of the membrane layer and the support layer, enables a more uniform distribution of the injection solution as it passes through the purification membrane, reducing membrane damage caused by local high pressure and improving the membrane's service life. Specifically, the membrane layer, under the action of a pore-forming agent, can form micropores, achieving the retention of large particles, microcrystals, and colloidal impurities, while simultaneously improving the flux retention rate of the purification membrane after prolonged filtration. In the support layer, the carboxyl groups of the carboxylated dextran undergo reversible dissociation during filtration, generating carboxyl anions and hydrogen ions. The carboxyl anions adsorb cationic impurities that pass through the membrane layer after filtration, while the hydrogen ions are released into the solution, thereby preventing the accumulation of cationic impurities within the membrane micropores, reducing the rate of flux decline due to membrane blockage, and thus extending the service life of the purification membrane.

[0009] Preferably, the thickness of the film layer is 100μm to 140μm, and the thickness of the support layer is 80μm to 90μm.

[0010] Preferably, the pore-forming agent is selected from one or both of polyvinylpyrrolidone or polyethylene glycol.

[0011] This invention defines the type of porogen, which has good hydrophilicity and compatibility and can form a stable and uniform casting solution with polyethersulfone resin.

[0012] Preferably, the polar aprotic organic solvent is selected from one or more of N-methylpyrrolidone, dimethyl sulfoxide, or N,N-dimethylacetamide.

[0013] This invention, by limiting the types of polar aprotic organic solvents, can efficiently dissolve polyethersulfone resin and pore-forming agents, ensuring the transparency of the casting solution and providing a foundation for uniform membrane formation. At the same time, the aforementioned polar aprotic organic solvents are easily removed by water washing, reducing the risk of residue and ensuring the safety and stability of filtration.

[0014] Preferably, the preparation method of the carboxylated dextran-grafted polyester nonwoven fabric includes the following steps:

[0015] S1. Mix polyester nonwoven fabric, sodium hydroxide aqueous solution and ethanol aqueous solution, and heat-treat at 60℃~80℃ to obtain pretreated nonwoven fabric.

[0016] S2. The pretreated nonwoven fabric, the aqueous solution of silane coupling agent and anhydrous ethanol are mixed and then heated at 25℃~35℃ to obtain the initially modified nonwoven fabric.

[0017] S3. The modified nonwoven fabric, carboxylated dextran aqueous solution and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution are mixed and the pH is adjusted to 5.0-6.0. The grafting reaction is carried out at 30℃-40℃ to obtain the carboxylated dextran-grafted polyester nonwoven fabric.

[0018] This invention utilizes sodium hydroxide and ethanol to directionally hydrolyze the ester bonds on the surface of polyester nonwoven fabric, introducing hydroxyl and carboxyl active groups. This allows the pretreated nonwoven fabric to introduce amino groups under the action of a silane coupling agent, which in turn grafts carboxylated dextran to form carboxylated dextran-grafted polyester nonwoven fabric.

[0019] Preferably, in S1, the ratio of the amount of polyester nonwoven fabric, sodium hydroxide aqueous solution and ethanol aqueous solution is 1g:(15-25)mL:(3-7)mL, the mass concentration of the sodium hydroxide aqueous solution is 3%-7%, and the volume concentration of the ethanol aqueous solution is 15%-25%.

[0020] Preferably, in S1, the heating treatment time is 30 min to 60 min.

[0021] More preferably, the heat treatment in S1 is carried out under stirring conditions, and the stirring speed is 130 r / min to 170 r / min.

[0022] This invention enables the gentle activation of the surface of polyester nonwoven fabric by limiting the parameters of S1, ensuring that ester bonds can be broken in a directional manner to introduce sufficient active groups, while avoiding excessive degradation that would reduce the strength of the support layer.

[0023] Preferably, in S2, the ratio of the amount of the initially modified nonwoven fabric, the aqueous solution of the silane coupling agent, and anhydrous ethanol is 5g:(50-150)mL:(950-1050)mL, and the volume concentration of the aqueous solution of the silane coupling agent is 1%-3%.

[0024] Preferably, in S2, the solute in the aqueous solution of the silane coupling agent is selected from one or both of 3-aminopropyltrimethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0025] Preferably, in S2, the heating treatment time is 30 min to 60 min.

[0026] More preferably, in S2, the heat treatment is carried out under stirring conditions, and the stirring speed is 130 r / min to 170 r / min.

[0027] This invention reduces the self-polymerization of silane coupling agents by limiting the parameters of S2.

[0028] Preferably, in S3, the ratio of the amount of the initially modified nonwoven fabric, the carboxylated dextran aqueous solution, and the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution is 3g:(40-60)mL:(5-15)mL, the mass concentration of the carboxylated dextran aqueous solution is 5%-10%, and the molar concentration of the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution is 0.05mol / L-0.15mol / L.

[0029] Preferably, in S3, the grafting reaction time is 100 min to 140 min.

[0030] More preferably, in S3, the grafting reaction is carried out under stirring conditions at a rotation speed of 50 r / min to 150 r / min.

[0031] This invention can control the grafting rate by limiting the parameters of S3, avoiding incomplete reaction or excessive cross-linking, and giving the support layer high activity and stability.

[0032] A second aspect of the present invention provides a method for preparing a purification membrane for the aforementioned compound mannitol injection, comprising the following steps:

[0033] Step 1: Mix polyethersulfone resin, pore-forming agent and polar aprotic organic solvent and stir until homogeneous and transparent. Let stand to obtain casting solution.

[0034] Step 2: After coating the casting solution onto the surface of the support layer, perform the first evaporation pore formation and the second evaporation pore formation to obtain a purification membrane for compound mannitol injection. The temperature of the first evaporation pore formation is 50℃~60℃ and the humidity is 10RH%~30RH. The temperature of the second evaporation pore formation is 20℃~25℃ and the humidity is 60RH%~80RH.

[0035] The present invention stirs polyethersulfone resin, pore-forming agent and polar aprotic organic solvent until uniform and transparent to ensure uniform composition of casting solution and avoid film defects caused by local concentration differences. At the same time, standing can eliminate air bubbles and prevent air bubbles from interfering with the pore structure of the film.

[0036] Meanwhile, this invention constructs a gradient pore size through first and second evaporation pore formation, achieving wide-range impurity classification filtration, improving the rejection rate and reducing the risk of clogging, thus giving the membrane layer better filtration efficiency and structural stability. Specifically, the first evaporation pore formation is performed in an environment with higher temperature and lower humidity. The higher temperature environment increases the solvent evaporation rate, while the lower humidity environment allows the solvent to diffuse rapidly into the air, resulting in rapid solvent removal and forming a loose layer with larger pore sizes on the membrane surface. The second evaporation pore formation is performed in an environment with lower temperature and higher humidity. The lower temperature and higher humidity environment reduces the solvent evaporation rate, allowing the solvent to evaporate slowly and forming a dense layer with smaller pore sizes inside the membrane layer.

[0037] In addition, the method for preparing the purification membrane for compound mannitol injection provided by the present invention is simple and controllable, requires no complex equipment, and is suitable for large-scale production.

[0038] Preferably, in step 1, the settling temperature is 25℃~35℃ and the settling time is 20min~40min.

[0039] More preferably, in step 1, the stirring temperature is 50℃~60℃ and the stirring speed is 250r / min~350r / min.

[0040] This invention improves the dissolution efficiency of polyethersulfone resin in polar aprotic organic solvents by limiting the parameters in step 1, avoiding particle residue caused by incomplete dissolution at low temperatures. At the same time, it reduces local concentration differences and ensures that the casting solution is uniform, transparent and free of flocculent matter.

[0041] Preferably, in step 2, the coating speed is 1.0 m / min to 2.0 m / min, the temperature is 20°C to 30°C, and the humidity is 25%RH to 75%RH.

[0042] Preferably, in step 2, the time for the first evaporation to form a pore is 10 min to 20 min.

[0043] Preferably, in step 2, the time for the second evaporation pore-forming process is 40 min to 60 min.

[0044] This invention ensures good film uniformity by limiting the coating speed, temperature, and humidity, thus preventing environmental conditions from affecting film performance. Simultaneously, by limiting the first evaporation pore-forming time, this invention ensures the formation of a loose layer on the film surface to improve film capacity; and by limiting the second evaporation pore-forming time, this invention ensures the formation of a dense layer inside the film to trap small-diameter impurities.

[0045] In summary, the purification membrane for compound mannitol injection provided by this invention effectively solves the problems of unstable retention and rapid flux decline in existing filter membranes through its membrane layer and support layer. Specifically, the membrane layer, based on polyethersulfone resin, forms micropores under the action of a pore-forming agent, which can precisely retain large particles, microcrystalline particles, and colloidal impurities, improving flux retention over long periods of filtration. The carboxylated dextran-grafted polyester nonwoven fabric of the support layer can adsorb cationic impurities through ion exchange, reducing the burden on the membrane layer, preventing clogging, and extending the service life of the filter membrane.

[0046] The purification membrane preparation method for compound mannitol injection provided by this invention improves grafting efficiency and stability, while constructing a gradient pore size structure, giving the filter membrane good filtration efficiency and structural stability. Furthermore, the preparation method provided by this invention is simple and controllable, requires no complex equipment, and is suitable for large-scale production. Detailed Implementation

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are merely one embodiment of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a purification membrane for compound mannitol injection, comprising a membrane layer and a support layer. The membrane layer comprises the following raw material components in parts by weight: 10 parts polyethersulfone resin, 5 parts polyvinylpyrrolidone, and 70 parts N-methylpyrrolidone. The support layer is a carboxylated dextran-grafted polyester nonwoven fabric. The thickness of the membrane layer is 100 μm, and the thickness of the support layer is 80 μm.

[0050] The preparation method of the carboxylated dextran-grafted polyester nonwoven fabric includes the following steps:

[0051] S1. Mix 10g of polyester nonwoven fabric, 150mL of sodium hydroxide aqueous solution with a mass concentration of 3% and 30mL of ethanol aqueous solution with a volume concentration of 15%, and heat at 60℃ and 130r / min for 30min to obtain pretreated nonwoven fabric.

[0052] S2. Mix 5g of the pretreated nonwoven fabric, 50mL of 1% 3-aminopropyltrimethoxysilane and 950mL of anhydrous ethanol, and heat at 25℃ and 130r / min for 30min to obtain the initial modified nonwoven fabric.

[0053] S3. Mix 3g of the pre-modified nonwoven fabric, 40mL of 5% carboxylated dextran aqueous solution and 5mL of 0.05mol / L 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution, adjust the pH to 5.0, and carry out the grafting reaction for 100min at 30℃ and 50r / min to obtain the carboxylated dextran-grafted polyester nonwoven fabric.

[0054] The preparation method of the purification membrane for the compound mannitol injection includes the following steps:

[0055] Step 1: Mix polyethersulfone resin, polyvinylpyrrolidone and N-methylpyrrolidone, stir at 50°C and 250 r / min until homogeneous and transparent, and let stand at 25°C for 20 min to obtain casting solution.

[0056] Step 2: The casting solution is coated onto the surface of the support layer at 20°C and 25% RH, with a coating thickness of 100 μm and a coating speed of 1.0 m / min. Holes are formed at 50°C and 10% RH for 10 min, and then at 20°C and 60% RH for 40 min to obtain a purification membrane for compound mannitol injection.

[0057] Example 2

[0058] This embodiment provides a purification membrane for compound mannitol injection, comprising a membrane layer and a support layer. The membrane layer comprises the following raw material components in parts by weight: 20 parts polyethersulfone resin, 15 parts polyethylene glycol, and 80 parts dimethyl sulfoxide. The support layer is a carboxylated dextran-grafted polyester nonwoven fabric. The thickness of the membrane layer is 140 μm, and the thickness of the support layer is 90 μm.

[0059] The preparation method of the carboxylated dextran-grafted polyester nonwoven fabric includes the following steps:

[0060] S1. Mix 10g of polyester nonwoven fabric, 250mL of sodium hydroxide aqueous solution with a mass concentration of 7% and 70mL of ethanol aqueous solution with a volume concentration of 25%, and heat at 80℃ and 170r / min for 60min to obtain pretreated nonwoven fabric.

[0061] S2. Mix 5g of the pretreated nonwoven fabric, 150mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane with a volume concentration of 3% and 1050mL of anhydrous ethanol, and heat at 35℃ and 170r / min for 60min to obtain the initial modified nonwoven fabric.

[0062] S3. Mix 3g of the pre-modified nonwoven fabric, 60mL of a 10% carboxylated dextran aqueous solution, and 15mL of a 0.15mol / L 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution, adjust the pH to 6.0, and carry out the grafting reaction at 40℃ and 150r / min for 140min to obtain the carboxylated dextran-grafted polyester nonwoven fabric.

[0063] The preparation method of the purification membrane for the compound mannitol injection includes the following steps:

[0064] Step 1: Mix polyethersulfone resin, polyethylene glycol and dimethyl sulfoxide, stir at 60°C and 350 r / min until homogeneous and transparent, and let stand at 35°C for 40 min to obtain casting solution.

[0065] Step 2: The casting solution is coated on the surface of the support layer at 30°C and 75% RH, with a coating thickness of 140 μm and a coating speed of 2.0 m / min. Holes are formed at 60°C and 30% RH for 20 min, and then at 25°C and 80% RH for 60 min to obtain a purification membrane for compound mannitol injection.

[0066] Example 3

[0067] This embodiment provides a purification membrane for compound mannitol injection, comprising a membrane layer and a support layer. The membrane layer comprises the following raw material components in parts by weight: 15 parts polyethersulfone resin, 10 parts polyethylene glycol, and 75 parts N,N-dimethylacetamide. The support layer is a carboxylated dextran-grafted polyester nonwoven fabric. The thickness of the membrane layer is 120 μm, and the thickness of the support layer is 85 μm.

[0068] The preparation method of the carboxylated dextran-grafted polyester nonwoven fabric includes the following steps:

[0069] S1. Mix 10g of polyester nonwoven fabric, 200mL of 5% sodium hydroxide aqueous solution and 50mL of 20% ethanol aqueous solution, and heat at 70℃ and 150r / min for 45min to obtain pretreated nonwoven fabric.

[0070] S2. Mix 5g of the pretreated nonwoven fabric, 100mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane with a volume concentration of 2% and 1000mL of anhydrous ethanol, and heat at 30℃ and 150r / min for 45min to obtain the initial modified nonwoven fabric.

[0071] S3. Mix 3g of the pre-modified nonwoven fabric, 50mL of 7% carboxylated dextran aqueous solution and 10mL of 0.1mol / L 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution, adjust the pH to 5.5, and carry out the grafting reaction at 35℃ and 100r / min for 120min to obtain the carboxylated dextran-grafted polyester nonwoven fabric.

[0072] The preparation method of the purification membrane for the compound mannitol injection includes the following steps:

[0073] Step 1: Mix polyethersulfone resin, polyethylene glycol and N,N-dimethylacetamide, stir at 55°C and 300 r / min until homogeneous and transparent, and let stand at 30°C for 30 min to obtain casting solution.

[0074] Step 2: The casting solution is coated onto the surface of the support layer at 25°C and 50% RH, with a coating thickness of 120 μm and a coating speed of 1.5 m / min. Holes are formed at 55°C and 20% RH for 15 min, and then at 22°C and 70% RH for 50 min to obtain a purification membrane for compound mannitol injection.

[0075] Comparative Example 1

[0076] This comparative example provides a purification membrane for compound mannitol injection, comprising a membrane layer and a support layer. The membrane layer comprises the following raw material components in parts by weight: 15 parts of polyethersulfone resin and 75 parts of N,N-dimethylacetamide; the support layer is a carboxylated dextran-grafted polyester nonwoven fabric; the thickness of the membrane layer is 120 μm, and the thickness of the support layer is 85 μm.

[0077] The preparation method of the carboxylated dextran-grafted polyester nonwoven fabric includes the following steps:

[0078] S1. Mix 10g of polyester nonwoven fabric, 200mL of 5% sodium hydroxide aqueous solution and 50mL of 20% ethanol aqueous solution, and heat at 70℃ and 150r / min for 45min to obtain pretreated nonwoven fabric.

[0079] S2. Mix 5g of the pretreated nonwoven fabric, 100mL of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane with a volume concentration of 2% and 1000mL of anhydrous ethanol, and heat at 30℃ and 150r / min for 45min to obtain the initial modified nonwoven fabric.

[0080] S3. Mix 3g of the pre-modified nonwoven fabric, 50mL of 7% carboxylated dextran aqueous solution and 10mL of 0.1mol / L 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution, adjust the pH to 5.5, and carry out the grafting reaction at 35℃ and 100r / min for 120min to obtain the carboxylated dextran-grafted polyester nonwoven fabric.

[0081] The preparation method of the purification membrane for the compound mannitol injection includes the following steps:

[0082] Step 1: Mix polyethersulfone resin and N,N-dimethylacetamide, stir at 55°C and 300 r / min until homogeneous and transparent, and let stand at 30°C for 30 min to obtain casting solution.

[0083] Step 2: The casting solution is coated onto the surface of the support layer at 25°C and 50% RH. After drying, a purification membrane for compound mannitol injection is obtained.

[0084] Comparative Example 2

[0085] This comparative example provides a purification membrane for compound mannitol injection, comprising a membrane layer and a support layer. The membrane layer comprises the following raw material components in parts by weight: 15 parts polyethersulfone resin, 10 parts polyethylene glycol, and 75 parts N,N-dimethylacetamide; the support layer is a polyester nonwoven fabric; the thickness of the membrane layer is 120 μm, and the thickness of the support layer is 85 μm.

[0086] The preparation method of the purification membrane for the compound mannitol injection includes the following steps:

[0087] Step 1: Mix polyethersulfone resin, polyethylene glycol and N,N-dimethylacetamide, stir at 55°C and 300 r / min until homogeneous and transparent, and let stand at 30°C for 30 min to obtain casting solution.

[0088] Step 2: The casting solution is coated onto the surface of the support layer at 25°C and 50% RH, with a coating thickness of 120 μm and a coating speed of 1.5 m / min. Holes are formed at 55°C and 20% RH for 15 min, and then at 22°C and 70% RH for 50 min to obtain a purification membrane for compound mannitol injection.

[0089] A mixture of mannitol and sorbitol with a concentration of 1 mg / mL was prepared. Commercially available silica microspheres (particle size 0.5 μm to 10 μm) were added to the mixture to make the concentration of silica microspheres 1 mg / mL. This simulated the compound mannitol injection solution to be purified. The 0.5 μm to 10 μm microsphere rejection rate, continuous filtration flux retention rate and anti-clogging cycle of the purification membrane were compared with those of the compound mannitol injection solutions in Examples 1-3 and Comparative Examples 1-2. The tensile strength of the unused filter membrane was measured according to GB / T 1040.3-2006 Determination of Tensile Properties of Plastics. The test results are shown in Table 1.

[0090] The method for detecting the retention rate of 0.5μm to 10μm microspheres includes the following steps: the compound mannitol injection solution to be purified is filtered through a compound mannitol injection purification membrane using a constant pressure filtration device (0.1MPa), the concentration of microspheres before and after filtration is measured using a laser particle size analyzer, and the retention rate is calculated as follows: retention rate = (1 - concentration of microspheres in filtrate / concentration of microspheres in original solution) × 100%;

[0091] The method for detecting the flux retention rate of continuous filtration for 10 hours includes the following steps: using purified water as the medium, the initial flux is measured at a pressure of 0.1 MPa, followed by continuous filtration of the compound mannitol injection solution to be purified for 10 hours, measuring the flux after 10 hours, and calculating the flux retention rate: flux retention rate = (flux after 10 hours / initial flux) × 100%.

[0092] The method for detecting the anti-clogging cycle includes the following steps: repeat the "filtration-backwashing" cycle, stopping each time the flux decreases by 30%, backwashing with purified water for 30 seconds, and recording the number of cycles in which the flux can recover to more than 80% of the initial value. This is the anti-clogging cycle.

[0093] Table 1 Performance test results of purification membrane for compound mannitol injection

[0094]

[0095] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A purification membrane for compound mannitol injection, characterized in that, It includes a membrane layer and a support layer, wherein the membrane layer is prepared from raw material components comprising the following parts by weight: 10 to 20 parts of polyethersulfone resin, 5 to 15 parts of pore-forming agent and 70 to 80 parts of polar aprotic organic solvent; The support layer is a carboxylated dextran-grafted polyester nonwoven fabric.

2. The purification membrane for compound mannitol injection according to claim 1, characterized in that, The thickness of the film layer is 100μm~140μm, and the thickness of the support layer is 80μm~90μm.

3. The purification membrane for compound mannitol injection according to claim 1, characterized in that, The pore-forming agent is selected from one or both of polyvinylpyrrolidone or polyethylene glycol; and / or The polar aprotic organic solvent is selected from one or more of N-methylpyrrolidone, dimethyl sulfoxide, or N,N-dimethylacetamide.

4. The purification membrane for compound mannitol injection according to claim 1, characterized in that, The preparation method of the carboxylated dextran-grafted polyester nonwoven fabric includes the following steps: S1. Mix polyester nonwoven fabric, sodium hydroxide aqueous solution and ethanol aqueous solution, and heat-treat at 60℃~80℃ to obtain pretreated nonwoven fabric. S2. The pretreated nonwoven fabric, the aqueous solution of silane coupling agent and anhydrous ethanol are mixed and then heated at 25℃~35℃ to obtain the pre-modified nonwoven fabric. S3. The modified nonwoven fabric, carboxylated dextran aqueous solution and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution are mixed and the pH is adjusted to 5.0~6.

0. The grafting reaction is carried out at 30℃~40℃ to obtain the carboxylated dextran-grafted polyester nonwoven fabric.

5. The purification membrane for compound mannitol injection according to claim 4, characterized in that, In S1, the ratio of the polyester nonwoven fabric, sodium hydroxide aqueous solution, and ethanol aqueous solution is 1g:(15~25)mL:(3~7)mL, the mass concentration of the sodium hydroxide aqueous solution is 3%~7%, and the volume concentration of the ethanol aqueous solution is 15%~25%; and / or In S1, the heating treatment time is 30 min to 60 min.

6. The purification membrane for compound mannitol injection according to claim 4, characterized in that, In S2, the ratio of the initially modified nonwoven fabric, the silane coupling agent aqueous solution, and anhydrous ethanol is 5g:(50~150)mL:(950~1050)mL, and the volume concentration of the silane coupling agent aqueous solution is 1%~3%; and / or In S2, the solute in the aqueous solution of the silane coupling agent is selected from one or both of 3-aminopropyltrimethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; and / or In S2, the heating treatment time is 30 min to 60 min.

7. The purification membrane for compound mannitol injection according to claim 4, characterized in that, In S3, the ratio of the initially modified nonwoven fabric, the carboxylated dextran aqueous solution, and the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution is 3g:(40~60)mL:(5~15)mL, the mass concentration of the carboxylated dextran aqueous solution is 5%~10%, and the molar concentration of the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide aqueous solution is 0.05mol / L~0.15mol / L; and / or In S3, the grafting reaction time is 100 min to 140 min.

8. The method for preparing the purification membrane for compound mannitol injection according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Mix polyethersulfone resin, pore-forming agent and polar aprotic organic solvent and stir until homogeneous and transparent. Let stand to obtain casting solution. Step 2: After coating the casting solution onto the surface of the support layer, perform the first evaporation pore formation and the second evaporation pore formation to obtain a purification membrane for compound mannitol injection. The temperature of the first evaporation pore formation is 50℃~60℃ and the humidity is 10RH%~30RH. The temperature of the second evaporation pore formation is 20℃~25℃ and the humidity is 60RH%~80RH.

9. The method for preparing the purification membrane for compound mannitol injection according to claim 8, characterized in that, In step 1, the settling temperature is 25℃~35℃ and the settling time is 20min~40min.

10. The method for preparing the purification membrane for compound mannitol injection according to claim 8, characterized in that, In step 2, the coating speed is 1.0 m / min to 2.0 m / min, the temperature is 20℃ to 30℃, and the humidity is 25%RH% to 75%RH%; and / or In step 2, the time for the first evaporation to create a pore is 10 min to 20 min; and / or In step 2, the time for the second evaporation pore formation is 40 min to 60 min.

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