A medical high-performance polylactic acid spunlace composite nonwoven material and a preparation method thereof

Abstract

The application relates to the technical field of water-jet non-woven materials, and particularly discloses a medical high-performance polylactic acid water-jet composite non-woven material and a preparation method thereof. First, polylactic acid fibers and coarse natural cellulose fibers are modified respectively, and a compatible agent PLGA-PEG-MDI block copolymer is prepared, so that the antibacterial property and the moisturizing property of the fibers are enhanced, and the good degradability of the fibers is maintained. The preparation process of the water-jet composite non-woven material is as follows: after viscose fibers are plasma-activated, the compatible agent and the modified polylactic acid fibers are sprayed and mixed, cross-laid, then the polylactic acid added with the compatible agent is melt-blown to the surface of the laid web, and finally the modified coarse natural cellulose is laid on the surface of the melt-blown layer, so that the water-jet composite non-woven material with good antibacterial property, unidirectional moisture permeability and degradability is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water-jet non-woven materials, in particular to a medical high-performance polylactic acid water-jet composite non-woven material and a preparation method thereof. BACKGROUND

[0002] Medical protective products include medical protective clothing and medical dressings and other products. At present, the medical protective products on the market are mostly made of polyethylene, polypropylene and other high molecular polymers through a series of processes such as spun-bonding, melt-blowing, film coating and flash evaporation. Since the raw materials of these protective products are mostly traditional petroleum-based compounds, they have the shortcomings of being difficult to degrade, poor comfort, poor air and moisture permeability, and hot wearing, which brings great physical burden to medical staff and causes environmental hazards.

[0003] Polylactic acid fiber is a green and environmentally friendly fiber, and its raw material is lactic acid, which is mainly obtained by fermentation of starch (corn, rice) and the like. After the product is made, it can be quickly decomposed in a natural state. Due to its natural degradability, moisture absorption and permeability, natural antibacterial property, softness and comfort, it can be widely used in medical and health products, household and decoration markets, and clothing markets, and the energy consumption in the production process is only 20%-50% of that of petroleum chemical products, and the carbon dioxide generated is only 20% of that of petroleum chemical products. Therefore, it is necessary to develop composite materials based on polylactic acid fiber to alleviate global environmental and energy problems. SUMMARY

[0004] The purpose of the present application is to provide a medical high-performance polylactic acid water-jet composite non-woven material and a preparation method thereof. The degradable fiber is used to form a medical composite material with good antibacterial performance and directional moisture management performance, which is applied to medical protection and medical dressings, and solves the problems of traditional petroleum-based medical protective materials, such as difficulty in degradation, poor comfort, poor air and moisture permeability, and hot wearing.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme:

[0006] A preparation method of a medical high-performance polylactic acid water-jet composite non-woven material, specifically comprising:

[0007] Step 1: The viscose fiber is plasma-activated, then sprayed with a PLGA-PEG-MDI block copolymer ethanol solution, and then mixed and cross-laid with zinc oxide-RAFT grafted polylactic acid fibers.

[0008] Step 2: After mixing the polylactic acid granules with the PLGA-PEG-MDI block copolymer, melt-blowing is performed on the laid web formed in step 1 to form an intermediate layer, and then pre-water jetting is performed for fixation.

[0009] Step 3: The attapulgite-chitosan modified crude natural cellulose fiber is laid on the intermediate layer after the pre-water jetting fixation, and then water jetting is performed to reinforce, and drying and winding are performed to obtain the medical high-performance polylactic acid water jetting composite nonwoven material.

[0010] During plasma activation, the mixed gas of helium and oxygen is used, the volume ratio of helium and oxygen is (8-9):(1-2), the power is 180-200w, and the activation time is 3-5min; during web laying, air flow assistance is used, the air flow speed is 0.8-1m / s, and the angle between the air flow and the web laying is 15-20°.

[0011] The PLGA-PEG-MDI block copolymer is used as a compatibilizer in the preparation process, after plasma activation of the viscose fiber, a large number of hydroxyl groups (-OH) and carboxyl groups (-COOH) exist on the surface, these active groups react with the isocyanate groups (-NCO) of the copolymer, the hydroxyl groups condense with the isocyanate to form urethane covalent bonds, the carboxyl groups react with the isocyanate groups to form amide bonds, the PLGA block of the copolymer interpenetrates and entangles with the polylactic acid molecular chain to form a physical bonding network, thereby greatly improving the interfacial compatibility between the polylactic acid and the viscose fiber, and inhibiting the interfacial delamination between the melt-blown polylactic acid fiber layer and the viscose fiber substrate; the PEG block of the copolymer reduces the melt viscosity and plays a plasticizing effect; in addition, the PLGA block dynamically coordinates the degradation behavior of the composite material by virtue of the degradation rate between polylactic acid and cellulose.

[0012] As a limitation of the present application, in step 1, the preparation method of zinc oxide-RAFT grafted polylactic acid fiber is as follows:

[0013] After mixing ethanol and deionized water uniformly, methyl methacrylate sulfobetaine is added, after stirring at 60-70℃, 300-400rpm for 20-25min, photoinitiator 2959 is added, and oxygen is removed by nitrogen bubbling for 10-15min to obtain a betaine ethanol dispersion, polylactic acid fiber is added to the betaine ethanol dispersion, and after immersion at 60-70℃, 300-400rpm for 15-20min, it is taken out, and grafted under the protection of nitrogen and 365nm ultraviolet light irradiation for 60-120s, the irradiation intensity is 25-35mW / cm 2 , to obtain grafted RAFT polylactic acid, the grafted RAFT polylactic acid is immersed in an ethanol dispersion containing carboxymethyl cellulose sodium and quaternary ammonium salt chitosan coated nano zinc oxide, vacuum assisted immersion is performed at (-0.08)-(-0.09)MPa for 15-20min, and then taken out, and then solidified at 50-60℃ for 20-30min, and then solidified at 60-70℃ for 20-30min to obtain zinc oxide-RAFT grafted polylactic acid fiber.

[0014] Under the action of ultraviolet irradiation and photoinitiator 2959, the sulfobetaine methacrylate is covalently connected with polylactic acid through chain transfer reaction to form a thioester bond (-C(=S)S-), and on the other hand, the sulfonic acid group (-SO3 - ) of the sulfobetaine methacrylate forms a strong hydrogen bond network with the hydroxyl group (-OH) of the viscose fiber, thereby enhancing the interfacial compatibility of polylactic acid and viscose fiber; the grafted sulfobetaine methacrylate can form a hydrophilic microzone on the side of polylactic acid due to its zwitterionic property, thereby enhancing the moisture conductivity of the composite material; the quaternary ammonium salt chitosan coated nano zinc oxide destroys the bacterial biofilm and the active oxygen (·OH) activated by the quaternary ammonium group (-N + (CH3)3) of the quaternary ammonium salt chitosan coated nano zinc oxide, thereby achieving synergistic antibacterial effect, and meanwhile, the chitosan coating layer forms a slow-release structure to reduce the release rate of zinc ions and enhance the antibacterial effect.

[0015] As a limitation of the present application, in the betaine ethanol dispersion liquid, the volume ratio of ethanol and deionized water is (7-8):(2-3), and the concentration of the sulfobetaine methacrylate is 0.5-0.6 g / mL; the ethanol dispersion liquid contains 0.1-0.2 wt% sodium carboxymethyl cellulose and 3-5 wt% quaternary ammonium salt chitosan coated nano zinc oxide.

[0016] As a limitation of the present application, the preparation method of the quaternary ammonium salt chitosan coated nano zinc oxide is as follows:

[0017] Silane coupling agent KH-550 is added to ethanol, and after stirring at 300-400 rpm for 15-20 min at 25-30℃, nano zinc oxide is added, the temperature is raised to 65-70℃, and reflux reaction is carried out at 300-400 rpm for 3-4 h; after the reaction is completed, filtration is carried out, washing is carried out with ethanol and acetone, and vacuum drying is carried out at 50-60℃ for 3-4 h to obtain silane modified nano zinc oxide;

[0018] Quaternary ammonium salt chitosan is added to acetic acid solution, stirring is carried out at 400-500 rpm for 1-2 h at 40-50℃ to obtain quaternary ammonium salt chitosan solution, and silane modified nano zinc oxide and polyethylene glycol are added to the quaternary ammonium salt chitosan solution, reaction is carried out at 50-60℃ in a water bath at 200-300 rpm for 2-3 h, centrifugal separation is carried out after the reaction is completed, and freeze-drying is carried out for 3-4 h to obtain quaternary ammonium salt chitosan coated nano zinc oxide.

[0019] The mass ratio of silane coupling agent KH-550 and nano zinc oxide is (0.8-1.0):(30-40), the concentration of the quaternary ammonium salt chitosan solution is 0.15-0.2 g / mL, and the mass ratio of silane modified nano zinc oxide, polyethylene glycol and quaternary ammonium salt chitosan solution is (70-80):(4-6):(75-85).

[0020] As a limitation of the present application, the preparation method of the PLGA-PEG-MDI block copolymer is:

[0021] Under the protection of nitrogen, lactic acid, glycolic acid and stannous octoate are mixed and reacted at 160-170 DEG C for 3-4 h. After the reaction is completed, the temperature is lowered to 150-160 DEG C, and vacuum dehydration is carried out at (-0.08)-(-0.09) MPa for 2-3 h. The PLGA prepolymer is obtained by mixing the PLGA prepolymer with polyethylene glycol, adding tetrabutyl titanate for catalysis, and polycondensing at 130-140 DEG C and 0.08-0.1 MPa for 3-5 h. After the polycondensation is completed, the temperature is lowered to 80-90 DEG C, diphenylmethane diisocyanate is added, and reaction is carried out under the protection of nitrogen for 1-2 h. After the reaction is completed, phosphoric acid is added to terminate the reaction, and the PLGA-PEG-MDI block copolymer is obtained.

[0022] As a limitation of the present application, the mass ratio of lactic acid, glycolic acid and stannous octoate is (55-65):(15-25):(0.04-0.06); and the mass ratio of the PLGA prepolymer, polyethylene glycol and diphenylmethane diisocyanate is (70-80):(30-40):(4-6).

[0023] As a limitation of the present application, the preparation method of the attapulgite-chitosan modified crude natural cellulose fiber is:

[0024] The attapulgite is added to an aqueous sulfuric acid solution, ultrasonically activated at 60-70 DEG C and 150-200 W for 0.5-1 h, filtered after the activation is completed, washed with deionized water, dried at 100-105 DEG C for 3-4 h, and then added to deionized water. Carboxymethyl chitosan, nano-silica sol and silane coupling agent KH-560 are added, uniformly stirred, and ultrasonically dispersed for 20-30 min to obtain an attapulgite impregnating solution.

[0025] Sodium hydroxide and urea are added to deionized water, uniformly stirred to obtain a mixed solution, and then the crude natural cellulose fiber is immersed in the mixed solution at 60-70 DEG C for 3-5 min, with a roll-off rate of 75-80%. After the roll extrusion, the fiber is immersed in the attapulgite impregnating solution at 60-70 DEG C for 20-30 min, taken out, and then roll-off rate is 70-75%. Finally, the fiber is stepwise solidified at 80-90 DEG C for 40-50 s, at 120-125 DEG C for 50-60 s, and at 90-100 DEG C for 30-40 s to obtain the modified crude natural cellulose fiber.

[0026] The specific surface area of the attapulgite is improved after acid activation, the micrometer level pore channel of the attapulgite is used as a main capillary wetting channel, and the nanometer silicon sol is selectively filled in the mesopore of the attapulgite, so that a micropore-mesopore dual-level wetting network is formed, and the wicking driving force is improved; the carboxyl groups of the carboxymethyl chitosan are chelated and coordinated with the aluminum silicate framework of the attapulgite, so that the binding capacity between the fibers and the functional groups is significantly enhanced, and the nanometer silicon sol is crosslinked between the fibers to form a Si-O-Si network, so that the mechanical strength and the processing performance of the material are improved.

[0027] As a limitation of the application, the mass ratio of the attapulgite and the aqueous sulfuric acid is (60-70):(80-100), the aqueous sulfuric acid contains 5-10 wt% of sulfuric acid; the mass ratio of the attapulgite, the carboxymethyl chitosan, the nanometer silicon sol and the silane coupling agent KH-550 is (60-70):(20-25):(40-50):(5-7); the mixed solution contains 3-5 wt% of sodium hydroxide and 8-10 wt% of urea.

[0028] As a limitation of the application, in step 1, 6-10 wt% of PLGA-PEG-MDI block copolymer ethanol solution is sprayed, the spraying amount is 15-20 mL / kg, and when the opening mixing is performed, the mass ratio of the activated viscose fiber and the zinc oxide-RAFT grafted polylactic acid fiber is (2-3):(4-5); in step 2, the mass ratio of the polylactic acid granules and the PLGA-PEG-MDI block copolymer is (95-97):(3-5), the melting temperature is 180-190 DEG C, the receiving distance is 15-18 cm, and the density of the formed intermediate layer is 13-17 g / m 2 ; the spunlace pressure is 30-35 bar; in step 3, the spunlace pressure is 20-25 bar, and the gradient drying is performed during drying, the drying is performed at 80-90 DEG C for 40-50 s, at 110-115 DEG C for 50-60 s, and at 90-100 DEG C for 30-40 s.

[0029] A medical high-performance polylactic acid spunlace composite nonwoven material is prepared by using the preparation method in any one of the above.

[0030] Compared with the prior art, the beneficial effects of the application are reflected in the following aspects:

[0031] The polylactic acid fiber is grafted with RAFT and is finished with quaternary ammonium salt chitosan coated nanometer zinc oxide modification, the wetting function and the antibacterial performance of the polylactic acid fiber are enhanced, the PLGA-PEG-MDI block copolymer is designed, the interface compatibility between the polylactic acid fiber and the viscose fiber is enhanced, the crude natural cellulose fiber is modified, the wetting and the antibacterial performance are enhanced, the uniformity and the consistency of the antibacterial performance are ensured through the common antibacterial modification of the fibers, the bacteria isolation effect is greater than 99.95%, and the top protection effect is achieved.

[0032] The application is prepared by embedding composite structure design, the inner layer is prepared by water jet composite process with polylactic acid and viscose fiber as raw materials; the middle layer is formed by melt blowing process with polylactic acid as raw material; the outer layer is formed by consolidation with coarse natural cellulose fiber. The mechanical properties and comfort of the material are improved by embedding layered distribution; the mechanical properties of the material are enhanced by directional puncture reinforcement process to form a three-dimensional interlocking network structure; the longitudinal wetting gradient of the fabric is formed to make the product have directional moisture-wicking performance. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. The terms used in the embodiments are used to describe specific specific embodiments, rather than to limit the protection scope of the application. The amount used in the embodiments is a laboratory test, which can be scaled up proportionally. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the protection scope of the application.

[0034] Polylactic acid fiber (fineness: 1.2 dtex), viscose fiber (fineness: 1.5 dtex), polylactic acid granules (polymerization degree = 500 ± 50), coarse natural cellulose fiber (fineness: 2.5 dtex), nano zinc oxide (particle size: 50 ± 5 nm), polyethylene glycol (PEG-400, hydroxyl value: 60 mgKOH / g), attapulgite (particle size: 450 ± 50 nm), nano silicon sol (particle size: 15 ± 5 nm, SiO2 content: ≥30 wt%).

[0035] Embodiment 1: A preparation method of a medical high-performance polylactic acid water jet composite non-woven material, specifically comprising:

[0036] Step 1: 0.8 g of silane coupling agent KH-550 is added to 200 g of ethanol, after stirring at 30℃ and 350 rpm for 15 min, 30 g of nano zinc oxide is added, the temperature is raised to 65℃, and the reflux reaction is carried out at 350 rpm for 3.5 h. After the reaction is completed, filtration is carried out, and washing is carried out with ethanol and acetone, and vacuum drying is carried out at 50℃ for 4 h to obtain silane modified nano zinc oxide;

[0037] Step 2: 75 g of quaternary ammonium salt chitosan is added to 400 mL of 1 wt% acetic acid solution, and stirring is carried out at 50℃ and 400 rpm for 1.5 h to obtain a quaternary ammonium salt chitosan solution. 60 g of silane modified nano zinc oxide and 4 g of polyethylene glycol are added to 75 g of the quaternary ammonium salt chitosan solution, and the reaction is carried out at 50℃ water bath and 250 rpm for 3 h. After the reaction is completed, centrifugal separation is carried out, and freeze-drying is carried out for 4 h to obtain quaternary ammonium salt chitosan coated nano zinc oxide;

[0038] Step 3: 210 mL of ethanol and 90 mL of deionized water were mixed uniformly, and then 150 g of methacrylic acid sulfobetaine was added. After stirring at 60 °C and 350 rpm for 20 min, 3 g of photoinitiator 2959 was added. Oxygen was removed by nitrogen bubbling for 15 min to obtain a betaine ethanol dispersion. The polylactic acid fiber was added to the betaine ethanol dispersion. After 20 min of immersion at 60 °C and 350 rpm, it was taken out and irradiated with 365 nm ultraviolet light for 90 s under nitrogen protection. The irradiation intensity was 30 mW / cm 2 , to obtain grafted RAFT polylactic acid. The grafted RAFT polylactic acid was immersed in an ethanol dispersion containing 0.1 wt% carboxymethyl cellulose sodium and 3 wt% quaternary ammonium salt chitosan-coated nano-zinc oxide. After vacuum-assisted immersion at -0.08 MPa for 15 min, it was taken out. After curing at 50 °C for 20 min and then at 70 °C for 20 min, zinc oxide-RAFT grafted polylactic acid fiber was obtained.

[0039] Step 4: Under nitrogen protection, 55 g of lactic acid, 15 g of glycolic acid, and 0.04 g of stannous octoate were added to a reaction kettle. The reaction was carried out at 170 °C for 3 h. After the reaction was completed, the temperature was lowered to 160 °C, and the water was removed under vacuum at -0.08 MPa for 2 h to obtain a PLGA prepolymer. 70 g of the PLGA prepolymer was mixed with 30 g of polyethylene glycol, and 0.1 g of tetrabutyl titanate was added as a catalyst. The condensation was carried out at 135 °C and 0.08 MPa for 4 h. After the condensation was completed, the temperature was lowered to 80 °C, and 4 g of diphenylmethane diisocyanate was added. The reaction was carried out under nitrogen protection for 1.5 h. After the reaction was completed, 0.05 g of phosphoric acid was added to terminate the reaction to obtain a PLGA-PEG-MDI block copolymer.

[0040] Step 5: 60 g of attapulgite was added to 80 g of 10 wt% sulfuric acid aqueous solution. After ultrasonic activation at 60 °C and 150 W for 1 h, it was filtered, washed with deionized water, and dried at 100 °C for 4 h. Then it was added to 1 L of deionized water. 20 g of carboxymethyl chitosan, 40 g of nano-silica sol, and 5 g of silane coupling agent KH-560 were added and stirred uniformly. After ultrasonic dispersion for 30 min, an attapulgite impregnation solution was obtained.

[0041] Step 6: Sodium hydroxide and urea were added to deionized water and stirred uniformly to obtain a mixed solution containing 3 wt% sodium hydroxide and 8 wt% urea. Then, the crude natural cellulose fiber was immersed in the mixed solution at 60 °C for 5 min with a rolling rate of 80%. After being squeezed by the roller, it was immersed in the attapulgite impregnation solution at 60 °C for 30 min and then taken out with a rolling rate of 75%. Finally, it was cured in stages at 80 °C for 40 s, at 120 °C for 50 s, and at 90 °C for 30 s to obtain attapulgite-chitosan modified crude natural cellulose fiber.

[0042] Step 7: Put the viscose fiber into the reaction chamber of the plasma activation device, and pass in a mixture of helium and oxygen (volume ratio 9:1) with a power setting of 180W. After 5 minutes of activation, take it out, spray 6wt% PLGA-PEG-MDI block copolymer ethanol solution, and the spraying amount is 15mL / kg. After spraying, mix it with the zinc oxide-RAFT grafted polylactic acid fiber at a mass ratio of 3:5. The opening roller speed is 800rpm, and the opening time is 8min. After opening, cross-lay the web with air-assisted directional transport at a wind speed of 0.8m / s and an angle of 15°. Mix the polylactic acid granules and PLGA-PEG-MDI block copolymer at a mass ratio of 95:5, and then melt-blow them onto the laid web at 185℃. The receiving distance is 18cm, and the intermediate layer formed is 15g / m 2 After melt-blowing, fix it with 30bar pressure pre-spunlace, then lay the attapulgite-chitosan modified coarse natural cellulose fiber, and reinforce it with 20bar low-pressure spunlace. Dry it at 80℃ for 40s, 110℃ for 50s, and 90℃ for 30s, and then wind it up to obtain a medical high-performance polylactic acid spunlace composite nonwoven material.

[0043] Example 2: A method for preparing a medical high-performance polylactic acid spunlace composite nonwoven material, specifically:

[0044] Step 1: Add 0.9g of silane coupling agent KH-550 to 200g of ethanol, stir at 30℃ and 350rpm for 15min, then add 30g of nano zinc oxide, heat to 65℃, and reflux at 350rpm for 3.5h. After the reaction is completed, filter, wash with ethanol and acetone, and vacuum dry at 50℃ for 4h to obtain silane-modified nano zinc oxide;

[0045] Step 2: Add 75g of quaternary ammonium salt chitosan to 400mL of 1wt% acetic acid solution, stir at 50℃ and 400rpm for 1.5h to obtain a quaternary ammonium salt chitosan solution. Add 65g of silane-modified nano zinc oxide and 4g of polyethylene glycol to the 75g of quaternary ammonium salt chitosan solution, and react at 50℃ water bath and 250rpm for 3h. After the reaction is completed, centrifuge and freeze-dry for 4h to obtain quaternary ammonium salt chitosan-coated nano zinc oxide;

[0046] Step 3: Mix 210mL of ethanol and 90mL of deionized water evenly, then add 155g of methacrylic acid sulfobetaine, stir at 60℃ and 350rpm for 20min, then add 3g of photoinitiator 2959, and bubble nitrogen to remove oxygen for 15min to obtain a betaine ethanol dispersion. Add polylactic acid fiber to the betaine ethanol dispersion, immerse at 60℃ and 350rpm for 20min, then take it out, irradiate it under nitrogen protection at 365nm ultraviolet light for 90s, and the irradiation intensity is 30mW / cm 2, and the grafted RAFT polylactic acid was immersed into an ethanol dispersion solution containing 0.1 wt% sodium carboxymethyl cellulose and 3 wt% quaternary ammonium salt chitosan-coated nano zinc oxide, taken out after vacuum-assisted immersion at -0.08 MPa for 15 min, and cured at 50 °C for 20 min and then at 70 °C for 20 min to obtain zinc oxide-RAFT grafted polylactic acid fibers;

[0047] Step 4: Under nitrogen protection, 55 g of lactic acid, 15 g of glycolic acid, and 0.04 g of stannous octoate were added to a reaction kettle, and reacted at 170 °C for 3 h. After the reaction was completed, the temperature was lowered to 160 °C, and vacuum dehydration was performed at -0.08 MPa for 2 h to obtain a PLGA prepolymer. 70 g of the PLGA prepolymer was mixed with 30 g of polyethylene glycol, and 0.1 g of tetrabutyl titanate was added for catalysis. Polycondensation was performed at 135 °C and 0.08 MPa for 4 h. After the polycondensation was completed, the temperature was lowered to 80 °C, and 4 g of diphenylmethane diisocyanate was added. Reaction was performed under nitrogen protection for 1.5 h. After the reaction was completed, 0.05 g of phosphoric acid was added to terminate the reaction to obtain a PLGA-PEG-MDI block copolymer;

[0048] Step 5: 65 g of attapulgite was added to 80 g of 10 wt% sulfuric acid aqueous solution, and ultrasonically activated at 60 °C and 150 W for 1 h. After the activation was completed, filtration was performed, and the product was washed with deionized water. After being dried at 100 °C for 4 h, the product was added to 1 L of deionized water, and 20 g of carboxymethyl chitosan, 40 g of nano-silica sol, and 5 g of silane coupling agent KH-560 were added. After being stirred uniformly, ultrasonic dispersion was performed for 30 min to obtain an attapulgite impregnation solution;

[0049] Step 6: Sodium hydroxide and urea were added to deionized water, and stirred uniformly to obtain a mixed solution containing 3 wt% sodium hydroxide and 8 wt% urea. Subsequently, the crude natural cellulose fibers were immersed in the mixed solution at 60 °C for 5 min, and the pick-up rate was 80%. After being extruded by a roller, the fibers were immersed in the attapulgite impregnation solution, taken out after being immersed at 60 °C for 30 min, and the pick-up rate was 75%. Finally, stepwise curing was performed at 80 °C for 40 s, at 120 °C for 50 s, and at 90 °C for 30 s to obtain attapulgite-chitosan modified crude natural cellulose fibers;

[0050] Step 7: Put the viscose fiber into the reaction chamber of the plasma activation device, and pass in a mixture of helium and oxygen (volume ratio 9:1) with a power setting of 180W. After 5 minutes of activation, take it out, spray 8wt% PLGA-PEG-MDI block copolymer ethanol solution, and the spraying amount is 15mL / kg. After spraying, mix it with zinc oxide-RAFT grafted polylactic acid fiber at a mass ratio of 3:6. The opening roller speed is 800rpm, and the opening time is 8min. After opening, cross-lay the web with air-assisted directional transport at a wind speed of 0.8m / s and an angle of 15°. Mix the polylactic acid granules and PLGA-PEG-MDI block copolymer at a mass ratio of 95:5, and then melt-blow them onto the laid web at 185℃. The receiving distance is 18cm, and the formed intermediate layer is 15g / m 2 After melt-blowing, fix it with 30bar pressure pre-spunlace, then lay the attapulgite-chitosan modified coarse natural cellulose fiber, and reinforce it with 20bar low-pressure spunlace. Dry it at 80℃ for 40s, 110℃ for 50s, and 90℃ for 30s, and then wind it up to obtain a medical high-performance polylactic acid spunlace composite nonwoven material.

[0051] Example 3: A method for preparing a medical high-performance polylactic acid spunlace composite nonwoven material, specifically:

[0052] Step 1: Add 1.0g of silane coupling agent KH-550 to 200g of ethanol. After stirring at 30℃ and 350rpm for 15min, add 30g of nano zinc oxide. Increase the temperature to 65℃ and reflux for 3.5h at 350rpm. After the reaction is complete, filter, wash with ethanol and acetone, and vacuum dry at 50℃ for 4h to obtain silane-modified nano zinc oxide.

[0053] Step 2: Add 75g of quaternary ammonium salt chitosan to 400mL of 1wt% acetic acid solution. Stir at 50℃ and 400rpm for 1.5h to obtain a quaternary ammonium salt chitosan solution. Add 70g of silane-modified nano zinc oxide and 4g of polyethylene glycol to the 75g of quaternary ammonium salt chitosan solution. React at 50℃ water bath and 250rpm for 3h. After the reaction is complete, centrifuge and freeze-dry for 4h to obtain quaternary ammonium salt chitosan-coated nano zinc oxide.

[0054] Step 3: Mix 210mL of ethanol and 90mL of deionized water evenly, then add 160g of methacrylic acid sulfobetaine. Stir at 60℃ and 350rpm for 20min, then add 3g of photoinitiator 2959. Bubble nitrogen to remove oxygen for 15min to obtain a betaine ethanol dispersion. Add polylactic acid fiber to the betaine ethanol dispersion, immerse at 60℃ and 350rpm for 20min, then take it out, irradiate it under nitrogen protection at 365nm ultraviolet light for 90s, and the irradiation intensity is 30mW / cm 2, and the grafted RAFT polylactic acid was immersed into an ethanol dispersion solution containing 0.1 wt% sodium carboxymethyl cellulose and 3 wt% quaternary ammonium salt chitosan-coated nano zinc oxide, taken out after vacuum-assisted immersion at -0.08 MPa for 15 min, and cured at 50 °C for 20 min and then at 70 °C for 20 min to obtain a zinc oxide-RAFT grafted polylactic acid fiber;

[0055] Step 4: 55 g of lactic acid, 15 g of glycolic acid, and 0.04 g of stannous octoate were added to a reaction kettle under nitrogen protection, and reacted at 170 °C for 3 h. After the reaction was completed, the temperature was lowered to 160 °C, and vacuum dehydration was performed at -0.08 MPa for 2 h to obtain a PLGA prepolymer. 70 g of the PLGA prepolymer was mixed with 30 g of polyethylene glycol, and 0.1 g of tetrabutyl titanate was added for catalysis. Polycondensation was performed at 135 °C and 0.08 MPa for 4 h. After the polycondensation was completed, the temperature was lowered to 80 °C, and 4 g of diphenylmethane diisocyanate was added. Reaction was performed under nitrogen protection for 1.5 h. After the reaction was completed, 0.05 g of phosphoric acid was added to terminate the reaction to obtain a PLGA-PEG-MDI block copolymer;

[0056] Step 5: 70 g of attapulgite was added to 80 g of 10 wt% sulfuric acid aqueous solution, and ultrasonically activated at 60 °C and 150 W for 1 h. After the activation was completed, filtration was performed, and the product was washed with deionized water. After being dried at 100 °C for 4 h, the product was added to 1 L of deionized water, and 20 g of carboxymethyl chitosan, 40 g of nano-silica sol, and 5 g of silane coupling agent KH-560 were added. After being stirred uniformly, ultrasonic dispersion was performed for 30 min to obtain an attapulgite impregnation solution;

[0057] Step 6: Sodium hydroxide and urea were added to deionized water, and stirred uniformly to obtain a mixed solution containing 3 wt% sodium hydroxide and 8 wt% urea. Subsequently, the crude natural cellulose fiber was immersed in the mixed solution at 60 °C for 5 min, and the pick-up rate was 80%. After being extruded by a roller, the product was immersed in the attapulgite impregnation solution, taken out after being immersed at 60 °C for 30 min, and the pick-up rate was 75%. Finally, stepwise curing was performed at 80 °C for 40 s, at 120 °C for 50 s, and at 90 °C for 30 s to obtain attapulgite-chitosan modified crude natural cellulose fiber;

[0058] Step 7: Put the viscose fiber into the reaction chamber of the plasma activation device, and pass in a mixture of helium and oxygen (volume ratio 9:1) with a power setting of 180W. After 5 minutes of activation, take it out, spray 10wt% PLGA-PEG-MDI block copolymer ethanol solution, and the spraying amount is 15mL / kg. After spraying, mix it with the zinc oxide-RAFT grafted polylactic acid fiber at a mass ratio of 3:7, and the opening roller speed is 800rpm. The opening time is 8min. After opening, cross-lay the net, and use airflow assisted directional transportation with a wind speed of 0.8m / s and an angle of 15°. Mix the polylactic acid granules and PLGA-PEG-MDI block copolymer at a mass ratio of 95:5, and then melt blow them onto the laid net at 185℃, with a receiving distance of 18cm. The formed intermediate layer is 15g / m 2 After melt blowing, fix it with 30bar pressure pre-spun, and then lay the attapulgite-chitosan modified coarse natural cellulose fiber, and reinforce it with 20bar low pressure spunlacing. Dry it at 80℃ for 40s, 110℃ for 50s, and 90℃ for 30s. Wind it up to get the medical high-performance polylactic acid spunlaced composite nonwoven material.

[0059] Based on Example 1, the following control experiments are carried out, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0060] Comparative Example 1: This comparative example relates to a method for preparing a medical high-performance polylactic acid spunlaced composite nonwoven material, which is different from Example 1 in that no PLGA-PEG-MDI block copolymer is added, specifically:

[0061] Step 1: Add 0.8g of silane coupling agent KH-550 to 200g of ethanol, stir at 30℃ and 350rpm for 15min, then add 30g of nano zinc oxide, heat to 65℃, and reflux at 350rpm for 3.5h. After the reaction is completed, filter, wash with ethanol and acetone, and vacuum dry at 50℃ for 4h to obtain silane modified nano zinc oxide;

[0062] Step 2: Add 75g of quaternary ammonium salt chitosan to 400mL of 1wt% acetic acid solution, stir at 50℃ and 400rpm for 1.5h to obtain a quaternary ammonium salt chitosan solution. Add 60g of silane modified nano zinc oxide and 4g of polyethylene glycol to the 75g of quaternary ammonium salt chitosan solution, and react at 50℃ water bath and 250rpm for 3h. After the reaction is completed, centrifugal separation, and freeze-drying for 4h, the quaternary ammonium salt chitosan coated nano zinc oxide is obtained.

[0063] Step 3: 210 mL of ethanol and 90 mL of deionized water were mixed uniformly, and then 150 g of methacrylic acid sulfobetaine was added. After stirring at 60°C and 350 rpm for 20 min, 3 g of photoinitiator 2959 was added, and nitrogen was bubbled to remove oxygen for 15 min to obtain a betaine ethanol dispersion. The polylactic acid fiber was added to the betaine ethanol dispersion, and after 20 min of immersion at 60°C and 350 rpm, it was taken out and irradiated with 365 nm ultraviolet light for 90 s under nitrogen protection, with an irradiation intensity of 30 mW / cm 2 , to obtain grafted RAFT polylactic acid. The grafted RAFT polylactic acid was immersed in an ethanol dispersion containing 0.1 wt% carboxymethyl cellulose sodium and 3 wt% quaternary ammonium salt chitosan-coated nano-zinc oxide, and then taken out after vacuum-assisted immersion at -0.08 MPa for 15 min. After solidification at 50°C for 20 min and then at 70°C for 20 min, zinc oxide-RAFT grafted polylactic acid fiber was obtained;

[0064] Step 4: 60 g of attapulgite was added to 80 g of 10 wt% sulfuric acid aqueous solution, and ultrasonic activation was performed at 60°C and 150 W for 1 h. After activation, filtration was performed, and the product was washed with deionized water. After drying at 100°C for 4 h, the product was added to 1 L of deionized water, and 20 g of carboxymethyl chitosan, 40 g of nano-silica sol, and 5 g of silane coupling agent KH-560 were added. After stirring and ultrasonic dispersion for 30 min, an attapulgite immersion solution was obtained.

[0065] Step 5: Sodium hydroxide and urea were added to deionized water, and the mixture was stirred to obtain a mixture containing 3 wt% sodium hydroxide and 8 wt% urea. Then, the crude natural cellulose fiber was immersed in the mixture at 60°C for 5 min, with a rolling rate of 80%. After rolling and extrusion, the fiber was immersed in the attapulgite immersion solution at 60°C for 30 min, and then taken out with a rolling rate of 75%. Finally, the fiber was solidified in stages at 80°C for 40 s, at 120°C for 50 s, and at 90°C for 30 s to obtain attapulgite-chitosan modified crude natural cellulose fiber.

[0066] Step 6: The viscose fiber was placed in the reaction chamber of the plasma activation equipment, and a mixture of helium and oxygen (volume ratio 9:1) was introduced. The power was set to 180 W, and the fiber was activated for 5 min. Then, the zinc oxide-RAFT grafted polylactic acid fiber was opened and mixed with the viscose fiber at a mass ratio of 3:5. The opening roller speed was 800 rpm, and the opening time was 8 min. After opening, the fibers were cross-laid, and airflow with a speed of 0.8 m / s and an angle of 15° was used to assist directional delivery during laying. The polylactic acid pellets were melted and sprayed onto the laid fibers at 185°C, with a receiving distance of 18 cm. The formed intermediate layer had a weight of 15 g / m 2, 30 bar pressure pre-water jetting fixation after melt blowing, then palygorskite-chitosan modified crude natural cellulose fiber is laid, 20 bar low pressure water jetting reinforcement, 80℃ drying for 40s, 110℃ drying for 50s, 90℃ drying for 30s, winding, to obtain a medical high-performance polylactic acid water jetting composite nonwoven material.

[0067] Comparative Example 2: This comparative example relates to a method for preparing a medical high-performance polylactic acid water jetting composite nonwoven material, which is different from Example 1 in that the polylactic acid fiber is not modified, specifically:

[0068] Step 1: Under nitrogen protection, 55g lactic acid, 15g glycolic acid and 0.04g stannous octoate were added to the reaction kettle, and reacted at 170℃ for 3h. After the reaction was completed, the temperature was lowered to 160℃, and dehydrated under vacuum at -0.08MPa for 2h to obtain a PLGA prepolymer. 70g of the PLGA prepolymer was mixed with 30g of polyethylene glycol, and 0.1g of tetrabutyl titanate was added as a catalyst. The condensation was carried out at 135℃ and 0.08MPa for 4h. After the condensation was completed, the temperature was lowered to 80℃, and 4g of diphenylmethane diisocyanate was added. The reaction was carried out under nitrogen protection for 1.5h. After the reaction was completed, 0.05g of phosphoric acid was added to terminate the reaction, and a PLGA-PEG-MDI block copolymer was obtained;

[0069] Step 2: 60g of palygorskite was added to 80g of 10wt% sulfuric acid aqueous solution, and ultrasonically activated at 60℃ and 150W for 1h. After the activation was completed, it was filtered, washed with deionized water, and dried at 100℃ for 4h. Then it was added to 1L of deionized water, and 20g of carboxymethyl chitosan, 40g of nano-silica sol and 5g of silane coupling agent KH-560 were added. After stirring uniformly, ultrasonic dispersion was carried out for 30min to obtain a palygorskite impregnating solution;

[0070] Step 3: Sodium hydroxide and urea were added to deionized water and stirred uniformly to obtain a mixed solution containing 3wt% sodium hydroxide and 8wt% urea. Then the crude natural cellulose fiber was immersed in the 60℃ mixed solution for 5min, and the roll-off rate was 80%. After the roll extrusion, it was immersed in the palygorskite impregnating solution at 60℃ for 30min, and then taken out, with a roll-off rate of 75%. Finally, it was solidified in steps at 80℃ for 40s, at 120℃ for 50s, and at 90℃ for 30s to obtain palygorskite-chitosan modified crude natural cellulose fiber;

[0071] Step 4: Put the viscose fiber into the reaction chamber of the plasma activation device, and pass in a mixture of helium and oxygen (volume ratio 9:1) with a power setting of 180W. After 5 minutes of activation, take it out, spray 6wt% PLGA-PEG-MDI block copolymer ethanol solution, and the spraying amount is 15mL / kg. After spraying, mix it with polylactic acid fiber at a mass ratio of 3:5. The opening roller speed is 800rpm, and the opening time is 8min. After opening, cross-lay the web with air-assisted directional transport at a wind speed of 0.8m / s and an angle of 15°. Mix the polylactic acid pellets and PLGA-PEG-MDI block copolymer at a mass ratio of 95:5, and then melt-blow them onto the laid web at 185℃. The receiving distance is 18cm, and the intermediate layer formed is 15g / m 2 After melt-blowing, fix it with 30bar pressure pre-spunlace, and then lay the attapulgite-chitosan modified coarse natural cellulose fiber. Fix it with 20bar low-pressure spunlace, dry it at 80℃ for 40s, 110℃ for 50s, and 90℃ for 30s, and wind it up to obtain a medical high-performance polylactic acid spunlace composite nonwoven material.

[0072] Comparative Example 3: This comparative example relates to a method for preparing a medical high-performance polylactic acid spunlace composite nonwoven material, which is different from Example 1 in that the coarse natural cellulose fiber is not modified. Specifically:

[0073] Step 1: Add 0.8g silane coupling agent KH-550 to 200g ethanol, stir at 30℃ and 350rpm for 15min, then add 30g nano zinc oxide, heat to 65℃, and reflux at 350rpm for 3.5h. After the reaction is completed, filter, wash with ethanol and acetone, and vacuum dry at 50℃ for 4h to obtain silane-modified nano zinc oxide;

[0074] Step 2: Add 75g quaternary ammonium salt chitosan to 400mL 1wt% acetic acid solution, stir at 50℃ and 400rpm for 1.5h to obtain a quaternary ammonium salt chitosan solution. Add 60g silane-modified nano zinc oxide and 4g polyethylene glycol to the 75g quaternary ammonium salt chitosan solution, react at 50℃ water bath and 250rpm for 3h, centrifuge after the reaction is completed, and freeze-dry for 4h to obtain quaternary ammonium salt chitosan-coated nano zinc oxide;

[0075] Step 3: Mix 210mL ethanol and 90mL deionized water uniformly, add 3g photoinitiator 2959 after stirring at 60℃ and 350rpm for 20min, and bubble nitrogen to remove oxygen for 15min to obtain a betaine ethanol dispersion. Add polylactic acid fiber to the betaine ethanol dispersion, immerse at 60℃ and 350rpm for 20min, take it out, irradiate it under nitrogen protection at 365nm ultraviolet light for 90s, and the irradiation intensity is 30mW / cm2 , the grafted RAFT polylactic acid was immersed into an ethanol dispersion solution containing 0.1wt% sodium carboxymethyl cellulose and 3wt% quaternary ammonium salt chitosan coated nano zinc oxide, taken out after vacuum assisted immersion at -0.08MPa for 15min, solidified at 50℃ for 20min and then solidified at 70℃ for 20min, to obtain zinc oxide-RAFT grafted polylactic acid fibers;

[0076] Step 4: 55g of lactic acid, 15g of glycolic acid and 0.04g of stannous octoate were added into a reaction kettle under nitrogen protection, and reacted at 170℃ for 3h. After the reaction was completed, the temperature was lowered to 160℃, and vacuum dehydration was performed at -0.08MPa for 2h to obtain a PLGA prepolymer. 70g of the PLGA prepolymer was mixed with 30g of polyethylene glycol, 0.1g of tetrabutyl titanate was added for catalysis, and polycondensation was performed at 135℃ and 0.08MPa for 4h. After the polycondensation was completed, the temperature was lowered to 80℃, 4g of diphenylmethane diisocyanate was added, and the reaction was performed under nitrogen protection for 1.5h. After the reaction was completed, 0.05g of phosphoric acid was added to terminate the reaction, to obtain a PLGA-PEG-MDI block copolymer;

[0077] Step 5: viscose fibers were placed in the reaction chamber of a plasma activation device, and a mixture of helium and oxygen gas (volume ratio 9:1) was introduced. The power was set to 180W, and the activation was performed for 5min. After the activation was completed, 6wt% of a PLGA-PEG-MDI block copolymer ethanol solution was sprayed, and the spraying amount was 15mL / kg. After the spraying was completed, the zinc oxide-RAFT grafted polylactic acid fibers were opened and mixed at a mass ratio of 3:5. The opening roller rotation speed was 800rpm, and the opening time was 8min. After the opening was completed, cross-laying was performed. During the cross-laying, airflow with a speed of 0.8m / s and an angle of 15° was used for auxiliary directional conveying. The polylactic acid granules and the PLGA-PEG-MDI block copolymer were mixed at a mass ratio of 95:5, and then were melt-blown onto the laid web at 185℃. The receiving distance was 18cm, and the formed intermediate layer was 15g / m 2 After the melt-blowing, 30bar pressure was used for water jetting to fix the material, and then the coarse natural cellulose was laid on the material. 20bar low pressure water jetting was used for reinforcement, and the material was dried at 80℃ for 40s, at 110℃ for 50s and at 90℃ for 30s, and then was wound, to obtain a medical high-performance polylactic acid water jetting composite nonwoven material.

[0078] Detection experiment:

[0079] Medical high-performance polylactic acid water jetting composite nonwoven material samples were prepared according to the respective examples and comparative examples, and the following tests were performed.

[0080] Antibacterial property test: the antibacterial property of the spunlace composite nonwoven material sample is tested according to the “Evaluation of antibacterial property of textiles Part 3: oscillation method” (GB / T 20944.3-2008), and the test bacteria are selected as Staphylococcus aureus, Escherichia coli and Candida albicans. The bacteria are diluted into a bacterial suspension of 10 6 CFU / mL after being cultured in a broth medium at 37°C for 24 h. The spunlace composite nonwoven material sample is cut into a size of 5 cm x 5 cm and sterilized at 120°C for 15 min. After sterilization, the sample is placed in a conical flask, 1 mL of the bacterial suspension is inoculated on the surface, and the sample is cultured at 37°C with oscillation at 200 rpm for 18 h. Then, the sample is taken out, eluted with 100 mL of neutralizing solution (0.5 wt% sodium thiosulfate and 3 wt% Tween-80), mixed with 9 mL of PBS after elution, diluted by 10 times, and 1 mL of the diluted solution is added to an agar culture plate. After being cultured at 37°C for 24 h, the colony count is performed, and the antibacterial rate of the sample is calculated.

[0081] Directional wetting test: the test is performed according to the “Evaluation of moisture management of textiles Part 2: dynamic water transmission method” (GB / T 21655.2-2009). Three samples of 9 cm x 9 cm of the spunlace composite nonwoven material are prepared, and the test is performed on both sides of each material. The side containing the polylactic acid fiber and the viscose fiber is the surface layer, and the side containing the coarse natural cellulose is the bottom layer. The material is placed on the sensor of a M290 liquid moisture tester (TearLab), and the tester is started. 0.2 g of test liquid is added to the surface layer within 20 s, and the one-way transmission index is calculated.

[0082] 180-day compost degradation test: 50 g of the spunlace composite nonwoven material sample is crushed into particles with a particle size of ≤2 mm, and the total organic carbon content is determined. Then, waste compost (meeting the requirements of ISO 17556) is prepared, and the moisture content, pH and volatile solid content of the compost are adjusted to 50%, 7.0 and 30%, respectively. The crushed particles and the adjusted compost are mixed uniformly at a dry weight ratio of 1:6, and then placed in a reactor. Oxygen is introduced into one end of the reactor at a flow rate of 0.1 L / min, and the exhaust pipe at the other end is inserted into a 0.4 mol / L sodium hydroxide solution. The sodium hydroxide solution is replaced every 24 h, and the reactor is oscillated twice a week to prevent solidification. Fresh compost is added to the reactor every month to maintain the activity of microorganisms, and the total weight of the added fresh compost is 5%. The release amount of carbon dioxide in the reactor is determined every month, and the same test is performed on the compost without the addition of the spunlace composite nonwoven material particles as a control. The biodegradation rate of the spunlace composite nonwoven material sample is calculated.

[0083]

[0084] Conclusion: It can be seen from the test data that the antibacterial rate of Staphylococcus aureus / Escherichia coli, the one-way moisture transfer index and the biodegradation rate in 180-day composting test of the medical high-performance polylactic acid spunlace composite nonwoven material sample prepared in the embodiment are all better than those of the comparative examples, the medical high-performance polylactic acid spunlace composite nonwoven material provided by the application has good antibacterial performance, one-way moisture transfer performance and degradability, and the composite nonwoven material can completely meet the demand of high-quality medical protective materials.

[0085] It will be apparent to those skilled in the art that the application is not limited to the details of the foregoing exemplary embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the application. The foregoing embodiments are therefore to be considered in all respects as illustrative only and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A method for preparing a high-performance medical polylactic acid spunlace composite nonwoven material, characterized in that: Specifically: Step 1: After plasma activation of viscose fibers, spray them with PLGA-PEG-MDI block copolymer ethanol solution, then mix them with zinc oxide-RAFT grafted polylactic acid fibers and cross-lay them into a web; Step 2: After mixing polylactic acid granules with PLGA-PEG-MDI block copolymer, the mixture is melt-blown onto the mesh formed in Step 1 to form an intermediate layer, and then pre-hydroentangled for fixation; Step 3: Lay the pre-hydroentangled intermediate layer with attapulgite-chitosan modified coarse natural cellulose fibers, reinforce it with hydroentanglement, dry and wind it to obtain medical high-performance polylactic acid hydroentangled composite nonwoven material. The preparation method of zinc oxide-RAFT grafted polylactic acid fiber is as follows: Add silane coupling agent KH-550 to ethanol, stir at 25-30℃ and 300-400 rpm for 15-20 min, then add nano zinc oxide, heat to 65-70℃, reflux at 300-400 rpm for 3-4 h, filter after reaction, wash with ethanol and acetone, and vacuum dry at 50-60℃ for 3-4 h to obtain silane-modified nano zinc oxide; Quaternary ammonium salt chitosan was added to an acetic acid solution and stirred at 40-50℃ and 400-500 rpm for 1-2 hours to obtain a quaternary ammonium salt chitosan solution. Silane-modified nano zinc oxide and polyethylene glycol were added to the quaternary ammonium salt chitosan solution and reacted in a water bath at 50-60℃ and 200-300 rpm for 2-3 hours. After the reaction was completed, the mixture was centrifuged and freeze-dried for 3-4 hours to obtain quaternary ammonium salt chitosan coated with nano zinc oxide. After thoroughly mixing ethanol and deionized water, add betaine sulfonate methacrylate. Stir at 60-70℃ and 300-400 rpm for 20-25 minutes, then add photoinitiator 2959. Deoxygenate under nitrogen bubbling for 10-15 minutes to obtain a betaine-ethanol dispersion. Add polylactic acid fibers to the betaine-ethanol dispersion and immerse them at 60-70℃ and 300-400 rpm for 15-20 minutes. After immersion, remove the fibers and graft them under nitrogen protection and irradiate with 365 nm ultraviolet light for 60-120 seconds at an irradiation intensity of 25-35 mW / cm². 2 Grafted RAFT polylactic acid was obtained. The grafted RAFT polylactic acid was impregnated in an ethanol dispersion containing sodium carboxymethyl cellulose and quaternary ammonium salt chitosan coated with nano zinc oxide. After impregnation under vacuum assisted by (-0.08)-(-0.09) MPa for 15-20 min, it was taken out and cured at 50-60℃ for 20-30 min and then cured at 60-70℃ for 20-30 min to obtain zinc oxide-RAFT grafted polylactic acid fiber. The preparation method of PLGA-PEG-MDI block copolymer is as follows: Under nitrogen protection, lactic acid, glycolic acid, and stannous octoate were mixed and reacted at 160-170℃ for 3-4 hours. After the reaction was completed, the temperature was lowered to 150-160℃ and dehydrated under vacuum at (-0.08)-(-0.09) MPa for 2-3 hours to obtain PLGA prepolymer. The PLGA prepolymer was mixed with polyethylene glycol, and tetrabutyl titanate was added as a catalyst. Polycondensation was carried out at 130-140℃ and 0.08-0.1 MPa for 3-5 hours. After the polycondensation was completed, the temperature was lowered to 80-90℃, diphenylmethane diisocyanate was added, and the reaction was carried out under nitrogen protection for 1-2 hours. After the reaction was completed, phosphoric acid was added to terminate the reaction to obtain PLGA-PEG-MDI block copolymer. The preparation method of attapulgite-chitosan modified crude natural cellulose fiber is as follows: Add attapulgite to a sulfuric acid aqueous solution and activate it by ultrasonication at 60-70℃ and 150-200W for 0.5-1h. After activation, filter, wash with deionized water, dry at 100-105℃ for 3-4h, add to deionized water, add carboxymethyl chitosan, nano silica sol and silane coupling agent KH-560, stir evenly, and ultrasonically disperse for 20-30min to obtain attapulgite impregnation solution. Sodium hydroxide and urea are added to deionized water and stirred until homogeneous to obtain a mixture. Then, crude natural cellulose fibers are immersed in the mixture at 60-70℃ for 3-5 minutes, with a roll yield of 75-80%. After being squeezed by rollers, the fibers are immersed in attapulgite impregnation solution at 60-70℃ for 20-30 minutes and then removed with a roll yield of 70-75%. Finally, the fibers are cured in stages: at 80-90℃ for 40-50 seconds, at 120-125℃ for 50-60 seconds, and at 90-100℃ for 30-40 seconds, to obtain modified crude natural cellulose fibers.

2. The preparation method of a medical high-performance polylactic acid spunlace composite nonwoven material according to claim 1, characterized in that: In the betaine ethanol dispersion, the volume ratio of ethanol to deionized water is (7-8):(2-3), and the concentration of betaine methyl methacrylate sulfonate is 0.5-0.6 g / mL; the ethanol dispersion contains 0.1-0.2 wt% sodium carboxymethyl cellulose and 3-5 wt% quaternary ammonium salt chitosan-coated nano zinc oxide.

3. The preparation method of a medical high-performance polylactic acid spunlace composite nonwoven material according to claim 1, characterized in that: The mass ratio of lactic acid, glycolic acid and stannous octoate is (55-65):(15-25):(0.04-0.06); the mass ratio of PLGA prepolymer, polyethylene glycol and diphenylmethane diisocyanate is (70-80):(30-40):(4-6).

4. The preparation method of a medical high-performance polylactic acid spunlace composite nonwoven material according to claim 1, characterized in that: The mass ratio of attapulgite to sulfuric acid aqueous solution is (60-70):(80-100), and the sulfuric acid aqueous solution contains 5-10 wt% sulfuric acid; the mass ratio of attapulgite, carboxymethyl chitosan, nano silica sol, and silane coupling agent KH-550 is (60-70):(20-25):(40-50):(5-7); the mixture contains 3-5 wt% sodium hydroxide and 8-10 wt% urea.

5. The preparation method of a medical high-performance polylactic acid spunlace composite nonwoven material according to claim 1, characterized in that: In step 1, a 6-10 wt% PLGA-PEG-MDI block copolymer ethanol solution is sprayed at a rate of 15-20 mL / kg. During the opening and mixing process, the mass ratio of activated viscose fiber to zinc oxide-RAFT grafted polylactic acid fiber is (2-3):(4-5). In step 2, the mass ratio of polylactic acid granules to PLGA-PEG-MDI block copolymer is (95-97):(3-5), the melting temperature is 180-190℃, the receiving distance is 15-18 cm, and the density of the resulting interlayer is 13-17 g / m³. 2 The hydroentangling pressure is 30-35 bar; in step 3, the hydroentangling pressure is 20-25 bar, and the drying is gradient drying: 80-90℃ for 40-50s, 110-115℃ for 50-60s, and 90-100℃ for 30-40s.

6. A medical high-performance polylactic acid spunlace composite nonwoven material, prepared by any one of claims 1-5.

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