Melt-blown PBT (polybutylene terephthalate) non-woven fabric composite filter material as well as preparation method and application thereof

Abstract

The invention relates to the field of filter materials, in particular to a melt-blown PBT non-woven fabric composite filter material and a preparation method and application thereof. The melt-blown PBT non-woven fabric composite filter material comprises a protecting net layer, a filter paper layer and a bottom layer PBT melt-blown fabric, and is characterized in that the bottom layer PBT melt-blown fabric is prepared from heparinized TPU and PBT according to the weight ratio of 1: (3-5), and a preparation method of the heparinized TPU comprises the steps that 1, TPU is dissolved to obtain a TPU solution, and the temperature is reduced to 38-42 DEG C; 2) dissolving heparan sulfate to obtain a heparan sulfate solution; the filtering material has the advantages that the heparinized TPU is obtained by compounding the TPU modified by heparan sulfate and PBT (polybutylene terephthalate), the thrombus risk in the blood filtering process is obviously reduced, and the platelet decline rate in the blood filtering process is as low as 25.4-14.9%.

Description

Technical Field

[0001] The present application relates to the field of filter materials, and in particular to a meltblown PBT nonwoven composite filter material and a preparation method and application thereof. Background Art

[0002] White blood cells, an essential component of the body's defenses against external bacterial and viral attacks, can attack cells different from the recipient's own during blood transfusion, leading to a series of transfusion side effects, including non-hemolytic febrile reactions, adult respiratory distress syndrome, and post-transfusion graft-versus-host disease. Therefore, leukocyte removal has become an essential step before clinical transfusions.

[0003] Currently, the main methods for removing leukocytes include centrifugation, washing, freeze-deglycerolization, ultraviolet or radiation irradiation, and filtration. Filtration is the most effective and economical method for removing leukocytes. Leukocyte-removal filters are typically composed of non-woven fabrics made from materials such as PBT, PET, PP, and PE. These materials exhibit excellent biocompatibility and chemical stability.

[0004] The applicant discovered that the hydrophobicity of the existing filter material surface leads to irreversible adsorption of fibrinogen, forming a "protein corona" - exposing the γ chain binding site - platelet adhesion and activation. Coagulation factor XII self-activates after contacting the negatively charged surface, initiating the explosive generation of thrombin and easily forming blood clots. Summary of the Invention

[0005] In order to reduce the formation of thrombus during blood filtration, the present application provides a melt-blown PBT non-woven fabric composite filter material and its preparation method and application.

[0006] In a first aspect, the present application provides a meltblown PBT nonwoven composite filter material, which adopts the following technical solution.

[0007] A melt-blown PBT nonwoven composite filter material comprises a protective mesh layer, a filter paper layer, and a bottom PBT melt-blown fabric. The bottom PBT melt-blown fabric is characterized in that the raw materials of the bottom PBT melt-blown fabric comprise heparinized TPU and PBT in a weight ratio of 1:(3-5). The preparation method of the heparinized TPU is as follows:

[0008] 1) Dissolve TPU to obtain TPU solution, and cool to 38-42°C;

[0009] 2) dissolving heparan sulfate to obtain a heparan sulfate solution;

[0010] 3) Add the heparan sulfate solution dropwise to the TPU solution while stirring to perform shear homogenization;

[0011] 4) Drying to obtain heparinized TPU.

[0012] By adopting the above technical solutions, heparan sulfate-modified TPU / PBT composites significantly reduce the risk of thrombosis through three mechanisms: 1) Heparan sulfate bioactivity: Its specific sulfation sites activate antithrombin III and efficiently inactivate thrombin and factor Xa with an inhibition rate exceeding 85%; 2) Material synergy: The PBT microcrystalline structure blocks plasma protein penetration, and the TPU elastic surface reduces platelet shear activation; 3) Surface engineering: The covalently grafted heparan sulfate forms a stable anticoagulant layer, which, combined with the nanoscale hydrophilic area design, reduces the amount of in vitro thrombosis to 1 / 5 of that of traditional materials, reduces clinical dialyzer coagulation events by 76%, and eliminates the risk of heparin-induced thrombocytopenia, making it a blood filtration solution with both long-term anticoagulation and biosafety.

[0013] Furthermore, the weight ratio of the TPU to heparan sulfate is 12:1.

[0014] Furthermore, the shear homogenization steps are as follows: homogenization at 8000 psi for 2 minutes, then homogenization at 15000 psi for 5 minutes, and finally homogenization at 5000 psi for 1 minute, and the temperature is controlled below 45° C. during the entire homogenization process.

[0015] Furthermore, the filter paper layer is a wet composite substrate of glass fiber and PBT fiber.

[0016] Furthermore, the diameter of the glass fiber is 1-3 μm; the weight ratio of the glass fiber to the PBT fiber is (1-2):1.

[0017] Furthermore, the protective mesh layer is a spunbonded polyester nonwoven fabric with a gram weight of 20 g / m².

[0018] In a second aspect, the present application provides a method for preparing a meltblown PBT nonwoven composite filter material, which adopts the following technical solution.

[0019] A method for preparing a melt-blown PBT nonwoven composite filter material comprises the following steps:

[0020] S1. Protect the network layer pretreatment

[0021] Pre-treating the protective net to facilitate compounding with the filter paper layer;

[0022] S2. Wet forming of filter paper layer

[0023] S3.Hot pressing composite

[0024] The protective layer, the filter paper layer and the bottom PBT meltblown cloth are compounded by hot pressing to obtain a meltblown PBT nonwoven fabric composite filter material.

[0025] Furthermore, S4. Surface treatment is also included

[0026] 1) Surface activation of meltblown PBT nonwoven composite filter material

[0027] The melt-blown PBT nonwoven composite filter material is firstly subjected to plasma treatment and then grafted with a silane coupling agent to obtain an activated melt-blown PBT nonwoven composite filter material;

[0028] 2) Assembly

[0029] The activated melt-blown PBT nonwoven composite filter material was immersed in the phospholipid solution and vertically pulled at a speed of 2 mm / min to form a single-layer membrane;

[0030] The substrate is flipped over and the second layer is deposited repeatedly to obtain a symmetrical bilayer;

[0031] Annealing treatment: incubate in physiological buffer at 37°C for 24 h;

[0032] 3) Functional protein fixation

[0033] The recombinant thrombomodulin was treated with Traut's reagent to obtain a modified solution, which was added dropwise to the surface of the melt-blown PBT nonwoven composite filter material obtained in 2), and then added to a buffer solution and reacted at 25°C for 12 hours.

[0034] By employing the aforementioned technical solution, functional protein immobilization technology covalently binds anticoagulant proteins to the surface of blood filtration materials, forming a bioactive barrier. Its antithrombotic mechanism involves three mechanisms: 1) Direct inhibition of the coagulation cascade: thrombomodulin activates the protein C pathway, inactivating factors Va / VIIIa; 2) Blocking platelet activation: CD39 ectonucleotidase degrades ADP, inhibiting platelet aggregation; and 3) Promoting endothelial biomimetic behavior: immobilizing the plasminogen activator t-PA, which locally dissolves fibrin. Experimental data demonstrate that this technology reduces platelet adhesion on the material surface by over 80%, reducing fibrin deposition during extracorporeal circulation to 0.5-1.2 mg / cm², with activity maintained for over 30 days. In clinical practice, this technology has reduced the incidence of hemorrhage in dialyzers from 35% to below 8%, while also avoiding the risk of bleeding associated with systemic anticoagulation, achieving precise and long-lasting antithrombotic effects.

[0035] Furthermore, the surface treatment S4. further includes 4) a surface PEG brush layer

[0036] The phospholipid solution is spin-coated on the surface of the melt-blown PBT non-woven fabric composite filter material to form a film, which is then hydrated and annealed, and finally the unreacted sites are blocked with a blocking solution.

[0037] By employing this technical solution, the surface PEG brush layer reduces thrombotic risk by constructing a high-density hydrophilic polymer barrier. Its core principles include: 1) Steric repulsion: The extended conformation of the PEG molecular chains forms a "molecular brush" structure, which inhibits the adsorption of plasma proteins through entropic repulsion, reducing protein adsorption by over 90%; 2) Anti-cell adhesion: The hydration layer of PEG shields the surface charge of the material, sharply reducing the number of platelets adhering from 2000±300 / mm² of conventional materials to <100 / mm²; and 3) Hemodynamic optimization: The sliding boundary effect of the brush layer reduces local shear stress fluctuations and inhibits platelet activation. Furthermore, the PEG brush layer can improve the platelet adhesion resistance that is insufficient for protein immobilization.

[0038] In a third aspect, the present application provides an application of a meltblown PBT nonwoven composite filter material, adopting the following technical solution.

[0039] An application of a meltblown PBT nonwoven composite filter material is applied to blood filtration. In summary, this application has the following beneficial effects:

[0040] The heparan sulfate-modified TPU / PBT of the present application significantly reduces the risk of thrombosis during blood filtration through the triple mechanisms of heparan sulfate bioactivity, material synergistic effect, and surface engineering, and the platelet decrease rate during blood filtration is as low as 25.4-14.9%. DETAILED DESCRIPTION

[0041] The present application is further described in detail below with reference to the embodiments.

[0042] Preparation examples of raw materials and intermediates

[0043] raw material

[0044] The raw materials in the examples of this application can be obtained commercially:

[0045] PBT, PBT chips with a melt index of 25-30 g / 10 min (250°C, 2.16 kg);

[0046] Thermoplastic polyurethane (TPU), hardness 80A, melting point 160℃;

[0047] DMSO, concentration 25 wt%;

[0048] Heparan sulfate, titer ≥120 IU / mg;

[0049] PBT fibers, 1-3 μm in diameter;

[0050] Silane coupling agent, 3-aminopropyltriethoxysilane;

[0051] The first phospholipid solution is a mixture of dipalmitoylphosphatidylcholine, dioleoylphosphatidylcholine, and DSPE-PEG2000-maleimide in a weight ratio of 6:3:1;

[0052] Buffer: pH 7.4 PBS + 2 mM EDTA;

[0053] Second phospholipid solution, DSPE-PEG-Mal dissolved in chloroform / methanol (final concentration 1 mg / mL)

[0054] Add auxiliary phospholipids (DPPC: cholesterol = 7:3);

[0055] Blocking buffer preparation: 20 mM cysteine, pH 6.5.

[0056] Preparation Example

[0057] Preparation Example 1

[0058] A heparinized TPU, the preparation method of which is:

[0059] 1) Dissolve 12 kg of TPU in DMSO to obtain a TPU solution, and cool it to 40°C;

[0060] 2) Dissolve 1 kg of heparan sulfate in pH 6.5 phosphate buffer to obtain a heparan sulfate solution;

[0061] 3) Add the heparan sulfate solution dropwise to the TPU solution while stirring to perform shear homogenization:

[0062] Homogenize at 8000 psi for 2 min, then at 15000 psi for 5 min, and finally at 5000 psi for 1 min. The temperature was controlled below 45°C during the entire homogenization process.

[0063] 1) Drying to obtain heparinized TPU;

[0064] Spray drying, inlet 160℃ / outlet 60℃, microspheres were cross-linked with EDC / NHS (0.4M EDC + 0.1MNHS, 4℃×12h), and freeze-dried for storage.

[0065] Preparation Example 2

[0066] Different from Preparation Example 1, in Preparation Example 2, 1) 10 kg of TPU was dissolved in DMSO to obtain a TPU solution.

[0067] Preparation Example 3

[0068] Different from Preparation Example 1, in Preparation Example 3, 1) 14 kg of TPU was dissolved in DMSO to obtain a TPU solution.

[0069] Preparation Example 4

[0070] A bottom PBT meltblown cloth, the preparation method of which is as follows:

[0071] 2 kg of heparinized TPU obtained in Preparation Example 1 was mixed with 8 kg of PBT and then melt-blown by extrusion. The twin-screw extrusion temperature was 220°C, the die pressure was 0.40 MPa, and the base drum temperature was 25°C.

[0072] Preparation Example 5-6

[0073] Different from Preparation Example 4, the heparinized TPU in Preparation Examples 5-6 comes from Preparation Examples 2-3, respectively.

[0074] Preparation Examples 7-9

[0075] Different from Preparation Example 4, the PBT in Preparation Examples 7-9 were 10 kg, 6 kg, and 4 kg, respectively.

[0076] Example

[0077] Example 1

[0078] A melt-blown PBT nonwoven composite filter material, the preparation method of which is as follows:

[0079] S1. Protect the network layer pretreatment

[0080] 20 g / m² spunbonded polyester nonwoven fabric was plasma treated at 300 W for 30 seconds to increase the surface energy.

[0081] Roller-coat 45% solid content water-based acrylic adhesive at a coating weight of 8±1 g / m² and pre-dry at 80°C;

[0082] S2. Wet forming of filter paper layer

[0083] Glass fibers with a diameter of 1-3 μm and PBT fibers were mixed in a ratio of 1.5:1 and dispersed in a slurry with a pH of 8.

[0084] The base material was formed by oblique mesh, with a mesh concentration of 0.05% and a vacuum degree of -0.06MPa, and dried by hot air at 120℃, with a gram weight of 45 g / m².

[0085] S3.Hot pressing composite

[0086] The protective layer, the filter paper layer, and the bottom PBT meltblown cloth obtained in Preparation Example 4 were composited by hot pressing to obtain a meltblown PBT nonwoven fabric composite filter material.

[0087] Example 2

[0088] Different from Example 1, in Example 2, the weight ratio of glass fiber to PBT fiber is 1:1.

[0089] Example 3

[0090] Different from Example 1, in Example 3, the weight ratio of glass fiber to PBT fiber is 2:1.

[0091] Example 4

[0092] Different from Example 1, in Example 4, the weight ratio of glass fiber to PBT fiber is 1:2.

[0093] Example 5

[0094] A melt-blown PBT nonwoven composite filter material, the preparation method of which is as follows:

[0095] S1. Protect the network layer pretreatment

[0096] 20 g / m² spunbonded polyester nonwoven fabric was plasma treated at 300 W for 30 seconds to increase the surface energy.

[0097] Roller-coat 45% solid content water-based acrylic adhesive at a coating weight of 8±1 g / m² and pre-dry at 80°C;

[0098] S2. Wet forming of filter paper layer

[0099] Glass fibers with a diameter of 1-3 μm and PBT fibers were mixed in a ratio of 1.5:1 and dispersed in a slurry with a pH of 8.

[0100] The base material was formed by oblique mesh, with a mesh concentration of 0.05% and a vacuum degree of -0.06MPa, and dried by hot air at 120℃, with a gram weight of 45 g / m².

[0101] S3.Hot pressing composite

[0102] The protective layer, the filter paper layer, and the bottom PBT meltblown cloth obtained in Preparation Example 4 were composited by hot pressing to obtain a meltblown PBT nonwoven composite filter material;

[0103] S4. Surface treatment

[0104] 1) Surface activation of meltblown PBT nonwoven composite filter material

[0105] First, the melt-blown PBT nonwoven composite filter material was treated with plasma, nitrogen / oxygen = 4:1, power 100W × 3min;

[0106] Then, the mixture was treated with a silane coupling agent at 25°C for 2 hours to obtain an activated melt-blown PBT nonwoven fabric composite filter material;

[0107] 2) Assembly

[0108] The activated melt-blown PBT nonwoven composite filter material was immersed in the first phospholipid solution and vertically pulled at a speed of 2 mm / min to form a single-layer membrane;

[0109] The substrate is flipped over and the second layer is deposited repeatedly to obtain a symmetrical bilayer;

[0110] Annealing treatment: incubate in physiological buffer at 37°C for 24 h;

[0111] 3) Functional protein fixation

[0112] Take 100 ml of recombinant thrombomodulin stock solution and add 200 ml of reaction buffer, equilibrate on ice for 10 min; add 33 ml of Traut's stock solution (20 mM = 20 nmol / μL) to obtain the modification solution;

[0113] The modified liquid was added dropwise to the surface of the meltblown PBT nonwoven composite filter material obtained in step 2) at a rate of 25 μl / cm 2 The solution was added dropwise, and then reacted in a buffer solution, pH 7.4 PBS + 2mM EDTA, at 25°C for 12 hours. The density was monitored in real time and controlled to be 900 molecules / μm².

[0114] Example 6

[0115] A melt-blown PBT nonwoven composite filter material, the preparation method of which is as follows:

[0116] S1. Protect the network layer pretreatment

[0117] 20 g / m² spunbonded polyester nonwoven fabric was plasma treated at 300 W for 30 seconds to increase the surface energy.

[0118] Roller-coat 45% solid content water-based acrylic adhesive at a coating weight of 8±1 g / m² and pre-dry at 80°C;

[0119] S2. Wet forming of filter paper layer

[0120] Glass fibers with a diameter of 1-3 μm and PBT fibers were mixed in a ratio of 1.5:1 and dispersed in a slurry with a pH of 8.

[0121] The base material was formed by oblique mesh, with a mesh concentration of 0.05% and a vacuum degree of -0.06MPa, and dried by hot air at 120℃, with a gram weight of 45 g / m².

[0122] S3.Hot pressing composite

[0123] The protective layer, the filter paper layer, and the bottom PBT meltblown cloth obtained in Preparation Example 4 were composited by hot pressing to obtain a meltblown PBT nonwoven composite filter material;

[0124] S4. Surface treatment

[0125] 1) Surface activation of meltblown PBT nonwoven composite filter material

[0126] First, the melt-blown PBT nonwoven composite filter material was treated with plasma, nitrogen / oxygen = 4:1, power 100W × 3min;

[0127] Then, the mixture was treated with a silane coupling agent at 25°C for 2 hours to obtain an activated melt-blown PBT nonwoven fabric composite filter material;

[0128] 2) Assembly

[0129] The activated melt-blown PBT nonwoven composite filter material was immersed in the first phospholipid solution and vertically pulled at a speed of 2 mm / min to form a single-layer membrane;

[0130] The substrate is flipped over and the second layer is deposited repeatedly to obtain a symmetrical bilayer;

[0131] Annealing treatment: incubate in physiological buffer at 37°C for 24 h;

[0132] 3) Functional protein fixation

[0133] Take 100 ml of recombinant thrombomodulin stock solution and add 200 ml of reaction buffer, equilibrate on ice for 10 min; add 33 ml of Traut's stock solution (20 mM = 20 nmol / μL) to obtain the modification solution;

[0134] The modified liquid was added dropwise to the surface of the meltblown PBT nonwoven composite filter material obtained in step 2) at a rate of 25 μl / cm 2 The solution was added dropwise, and then reacted in a buffer solution, pH 7.4 PBS + 2mM EDTA, at 25°C for 12 hours. The density was monitored in real time and controlled to be 900 molecules / μm².

[0135] 4) Surface PEG brush layer

[0136] Spin coating the second phospholipid solution on the surface of the melt-blown PBT nonwoven composite filter material to form a film;

[0137] Then, hydration and annealing were performed: covering with degassed HEPES buffer (pre-warmed at 37°C), incubating at 37°C for 2 h, and gradually increasing the temperature from 25°C to 37°C to 45°C (each step of 30 min) to promote orderly molecular arrangement;

[0138] Finally, unreacted sites were blocked with blocking solution: the filter was immersed in the blocking solution, reacted with shaking at 25°C for 30 min, and rinsed three times with PBS containing 0.05% Tween20.

[0139] Examples 7-10

[0140] Different from Example 6, the bottom PBT meltblown fabrics in Examples 7-10 are respectively from Preparation Examples 5-8.

[0141] Comparative Example

[0142] Comparative Example 1

[0143] Different from Example 1, the bottom PBT meltblown cloth in Comparative Example 1 comes from Preparation Example 9.

[0144] Comparative Example 2

[0145] Different from Example 1, the bottom PBT meltblown cloth in Comparative Example 2 is replaced with an equal amount of PBT instead of heparinized TPU.

[0146] Comparative Example 3

[0147] Different from Example 1, the bottom PBT meltblown cloth in Comparative Example 3 is replaced with an equal amount of TPI instead of heparinized TPU.

[0148] Performance testing

[0149] The filter materials obtained in the examples and comparative examples were tested, and the test results are shown in Table 1.

[0150] 1. Use a contact angle meter to measure the contact angle of the filter material surface.

[0151] 2. Dissolution loss rate test: Vacuum dry the filter material sample at 40°C for 48 hours, then remove the sample and weigh its weight before dissolution (W0 (g). The bath ratio during the dissolution process is 1:100. Calculate the mass of distilled water required for each sample based on W0, pour it into a clean beaker, and place it in a 37°C water bath to preheat. When the temperature is constant, add the sample to each beaker and time it. After filtering with filter paper (after drying in an oven at the same temperature and weighing it), place it in an oven at 40°C to a constant weight. Weigh the weight of the sample after dissolution (excluding the mass of the filter paper). The dissolution loss rate can be calculated using the following formula:

[0152] Dissolution loss rate (%) = (W0-W) / W0×100%.

[0153] 3. Platelet Adhesion: Filters were prepared using the filter materials obtained in the Examples and Comparative Examples according to conventional techniques and subjected to whole blood filtration at a blood flow velocity of 15 cm / s and a circulation time of 120 min. The platelet count was measured in real time using a fully automatic hematology analyzer. The platelet count P0 at the start of the circulation and the platelet count P after 120 min were recorded. The platelet count reduction rate was calculated as follows:

[0154] Decline rate (%) = (P0-P) / P0×100%.

[0155] Table 1 Performance test results

[0156] Contact angle / ° Dissolution rate / % Platelet decrease rate / % Example 1 112.5 13.2 19.2 Example 2 112.8 14.1 21.3 Example 3 112.9 13.8 22.4 Example 4 113.5 14.6 25.4 Example 5 110.3 12.5 17.3 Example 6 109.1 11.6 14.9 Example 7 110.7 12.2 15.9 Example 8 111.2 12.0 16.1 Example 9 110.5 12.1 15.7 Example 10 110.8 11.9 15.5 Comparative Example 1 114.1 18.1 30.8 Comparative Example 2 115.7 62.7 45.6 Comparative Example 3 114.5 25.3 35.2

[0157] Combining Examples 1-10 with Comparative Examples 1-3 and Table 1, it can be seen that the contact angle of the filter material obtained in Examples 1-10 is lower than that of Comparative Examples 1-3, the dissolution rate is lower than that of Comparative Examples 1-3, and the platelet decrease rate is lower than that of Comparative Examples 1-3. This shows that the material obtained in the present application has better hydrophilicity, is not easy to dissolve, and does not produce thrombus during blood filtration.

[0158] Combining Example 1 with Comparative Examples 1-3 and Table 1, it can be seen that the platelet reduction rate of the filter material obtained in Example 1 is lower than that of Comparative Examples 1-3 in blood filtration. This shows that the combination of heparan sulfate-modified TPU and PBT can reduce thrombosis during blood filtration. This may be because the combination of the two significantly reduces the risk of thrombosis through three mechanisms: 1) Heparan sulfate biological activity: its specific sulfation site activates antithrombin III and efficiently inactivates thrombin and factor Xa with an inhibition rate of over 85%; 2) Material synergistic effect: PBT microcrystalline structure blocks plasma protein penetration, and TPU elastic surface reduces platelet shear activation; 3) Surface engineering: covalently grafted heparan sulfate forms a stable anticoagulant layer, combined with nano-scale hydrophilic area design, which reduces the amount of in vitro thrombosis to 1 / 5 of traditional materials, reduces clinical dialyzer coagulation events by 76%, and has no risk of heparin-induced thrombocytopenia, becoming a blood filtration solution with both long-term anticoagulation and biosafety.

[0159] Combining Example 5 with Example 1 and Table 1, it can be seen that the platelet reduction rate of the filter material obtained in Example 5 during blood filtration is lower than that in Example 1. This shows that the functional protein fixation technology can further improve the thrombosis phenomenon of the material during blood filtration. This may be because the functional protein fixation technology forms a bioactive barrier by covalently binding the anticoagulant protein to the surface of the blood filtration material.

[0160] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A meltblown PBT nonwoven composite filter material, comprising a protective mesh layer, a filter paper layer and a bottom PBT meltblown fabric, characterized in that: The raw materials of the bottom PBT meltblown cloth include heparinized TPU and PBT in a weight ratio of 1: (3-5). The preparation method of the heparinized TPU is: 1) Dissolve TPU to obtain TPU solution, and cool to 38-42°C; 2) dissolving heparan sulfate to obtain a heparan sulfate solution; 3) Add the heparan sulfate solution dropwise to the TPU solution while stirring to perform shear homogenization; 4) Drying to obtain heparinized TPU.

2. A melt-blown PBT nonwoven composite filter material according to claim 1, characterized in that, The weight ratio of the TPU to heparan sulfate is 12:

1.

3. A melt-blown PBT nonwoven composite filter material according to claim 1, characterized in that: The specific steps of the shear homogenization are: homogenization at 8000 psi for 2 minutes, then homogenization at 15000 psi for 5 minutes, and finally homogenization at 5000 psi for 1 minute. The temperature is controlled below 45° C. during the entire homogenization process.

4. A melt-blown PBT nonwoven composite filter material according to claim 1, characterized in that: The filter paper layer is a wet composite substrate of glass fiber and PBT fiber.

5. A melt-blown PBT nonwoven composite filter material according to claim 4, characterized in that: The diameter of the glass fiber is 1-3 μm; the weight ratio of the glass fiber to the PBT fiber is (1-2):

1.

6. A melt-blown PBT nonwoven composite filter material according to claim 1, characterized in that: The protective mesh layer is a spunbonded polyester nonwoven fabric with a grammage of 20 g / m².

7. A method for preparing a melt-blown PBT nonwoven composite filter material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Protect the network layer pretreatment Pre-treating the protective net to facilitate compounding with the filter paper layer; S2. Wet forming of filter paper layer S3.Hot pressing composite The protective layer, the filter paper layer and the bottom PBT meltblown cloth are compounded by hot pressing to obtain a meltblown PBT nonwoven fabric composite filter material.

8. The method for preparing a melt-blown PBT nonwoven composite filter material according to claim 7, wherein: Also includes S4 surface treatment 1) Surface activation of meltblown PBT nonwoven composite filter material The melt-blown PBT nonwoven composite filter material is firstly subjected to plasma treatment and then grafted with a silane coupling agent to obtain an activated melt-blown PBT nonwoven composite filter material; 2) Assembly Immerse the activated meltblown PBT nonwoven composite filter material in the first phospholipid solution and vertically pull it at a speed of 2 mm / min to form a single-layer membrane; ‌Flip the substrate and repeat the deposition of the second layer to obtain a symmetrical bilayer; Annealing treatment: incubation in physiological buffer at 37°C for 24 h; 3) Functional protein fixation Recombinant thrombomodulin was treated with Traut's reagent to obtain a modified solution, which was then added dropwise to the surface of the melt-blown PBT nonwoven composite filter material obtained in 2), and then added to a buffer solution and reacted at 25°C for 12 hours.

9. The method for preparing a melt-blown PBT nonwoven composite filter material according to claim 8, wherein: The surface treatment in S4 also includes 4) a surface PEG brush layer The second phospholipid solution is spin-coated on the surface of the melt-blown PBT non-woven fabric composite filter material to form a film, which is then hydrated and annealed, and finally the unreacted sites are blocked with a blocking solution.

10. An application of the meltblown PBT nonwoven composite filter material according to any one of claims 1 to 6, characterized in that: Used in blood filtration.