A manufacturing method of an automotive sound insulation felt

Abstract

The present invention discloses a manufacturing method of an automotive sound insulation felt. Poly lactic acid fiber is used as a raw material, and its flame retardancy is increased through modification. Hollow porous fibers are prepared by electrospinning. After the web is needled into a blanket, due to the characteristics of loose pores and interconnected open pores, sound waves penetrate into the pores of the material, are subjected to the friction and viscous resistance of air molecules, and cause the fine fibers to vibrate mechanically, thereby converting sound energy into heat energy and reducing noise. The present invention conducts flame retardant modification on poly lactic acid fiber and loads MnO2 particles. Due to the hollow porous characteristics of poly lactic acid fiber, it can adsorb volatile small molecules in the vehicle and absorb moisture. And MnO2 can oxidize and decompose aldehyde and aromatic volatile substances under normal temperature and non-light environment, solving the problems of adsorption and decomposition of carcinogenic substances in the vehicle. Moreover, the thermal stability of poly lactic acid fiber is comparable to that of PVC, and no harmful gases are produced during pyrolysis. PLA can form a weak acidic environment on the surface, which has antibacterial and mildew-proof effects.

Description

Technical Field

[0001] The present invention relates to the field of automotive interior manufacturing, such as the field of sound-absorbing material manufacturing, and particularly relates to a manufacturing method of an automotive sound insulation felt. Background Art

[0002] Automobile carpets not only serve as interior decorations in the vehicle, but also are important sound-absorbing / insulating and shock-absorbing materials. Sound-absorbing and insulating materials need to have excellent sound-absorbing properties, flame retardancy, heat resistance, and heat insulation properties, and need to be applicable to maintaining no generation of volatile harmful gases at a high temperature of 150 °C and room temperature.

[0003] Chinese Patent CN102529840A discloses a multi-layer structure automotive sound insulation pad and its manufacturing method. The sound insulation pad is composed of a felt hard sound insulation material with a density of 200-220 kg / m 3 and a polyurethane soft sound insulation material with a density of 60-70 kg / m 3 formed by the self-adhesion of polyurethane. The polyurethane soft sound insulation material used in this patent has the best sound-absorbing effect among current sound-absorbing materials. However, polyurethane will undergo thermal decomposition above 120 °C, generating aromatic volatiles. The molten fibers in the felt hard sound insulation material generally use PET and PP fibers, and glue is often used for bonding when the sound insulation material and the sound-absorbing material are compounded. Therefore, the automotive sound insulation pad generally remains a lot of phenolic, aldehyde, and aromatic volatile carcinogenic substances.

[0004] However, using other fibers to replace the existing sound insulation materials and sound-absorbing materials will reduce the sound-absorbing effect and shock-absorbing effect, resulting in a poor driving experience of the vehicle. Summary of the Invention

[0005] The present invention uses a naturally extracted polylactic acid fiber as the base material, increases its flame retardancy through modification, and prepares hollow porous fibers through electrospinning. After the hollow porous fibers are laid and needled into a blanket, due to the characteristics of loose pores and interconnected open pores, sound waves penetrate into the pores of the material, are subjected to air molecule friction and viscous resistance, and cause the fine fibers to vibrate mechanically, thereby converting sound energy into heat energy and reducing noise. The present invention has carried out flame retardant modification and loaded MnO2 particles on the polylactic acid fiber. Due to the hollow porous characteristics of the polylactic acid fiber, it can adsorb volatile small molecules in the car and absorb moisture. And MnO2 can act as a catalyst under normal temperature and non-light environment to oxidize and decompose aldehyde and aromatic volatile substances, thus solving the problem of adsorption and decomposition of carcinogenic substances in the car. Moreover, the thermal stability of the polylactic acid fiber is comparable to that of PVC, no harmful gases are produced during pyrolysis, and PLA can form a weakly acidic environment on the surface, which has antibacterial and antifungal effects. Using the automotive sound insulation felt of the present invention as the upper layer material of the polyurethane soft sound insulation material not only solves the problems of sound absorption and insulation and utilizes the shock absorption of the polyurethane soft sound insulation material, but also adsorbs and decomposes harmful volatile substances, and also isolates the water and beverages that may be spilled in the car from the polyurethane soft sound insulation material, avoiding mildew and decomposition of the polyurethane soft sound insulation material.

[0006] The technical solution of the present invention is: a manufacturing method of an automotive sound insulation felt, including the following steps: The hollow porous phosphorus-containing chain-extended polylactic acid fiber loaded with MnO2 particles is subjected to carding and web laying treatment to obtain composite fibers, and the composite fibers are subjected to needling processing, and finally the product after needling is hot-pressed and compounded to obtain an automotive sound insulation felt.

[0007] The MnO2 particles are γ-MnO2.

[0008] Further, the hollow porous phosphorus-containing chain-extended polylactic acid fiber loaded with MnO2 particles is prepared through the following steps:

[0009] (1) Add L-lactic acid to the reaction kettle, stir, heat and dehydrate under reduced pressure in a nitrogen atmosphere, condense, and then add 1,4-butanediol and stannous chloride according to 1 wt% and 0.5 wt% of the mass of lactic acid, raise the temperature to 160-180 °C, and react at 200-40 Pa until the acid value is less than 3, then stop the reaction to obtain prepolymerized lactic acid;

[0010] (2) Charge the phosphorus oxychloride chain extender into the reaction kettle according to 50-200% of the molar amount of the prepolymerized lactic acid, and react at 160-180 °C and 10-100 Pa for 0.5-3 h to obtain phosphorus-containing chain-extended polylactic acid;

[0011] (3) The phosphorus-containing chain-extended polylactic acid is dissolved in chloroform and then mixed into DMF to prepare a shell spinning solution. The mass ratio of chloroform to DMF is 5-11:1. Then, sodium chlorate as an oxidant is added to the Mn(NO3)2 solution, and then PVP is poured in and mixed and dissolved in DMF to prepare a core spinning solution;

[0012] (4) The prepared shell spinning solution and core spinning solution are respectively injected into the outer needle and inner needle of a coaxial electrospinning needle. At the same time, an electrostatic generator is connected to the coaxial electrospinning needle for electrospinning, and a roller receiving device is used for receiving to make nascent fibers. Subsequently, the obtained nascent fibers are immersed in deionized water at room temperature for more than 12 h, so that the PVP / DMF and sodium hypochlorite solution in the core layer are dissolved in water to form hollow fibers. Then, the hollow fibers after water bath are freeze-dried to obtain hollow porous phosphorus-containing chain-extended polylactic acid fibers loaded with MnO2 particles.

[0013] Preferably, the molecular weight of the phosphorus-containing chain-extended polylactic acid is 1000-10000.

[0014] Preferably, the phosphorus oxychloride chain extender is monomolecular phosphorus oxychloride or oligomeric phosphorus oxychloride, and the molecular weight of the oligomeric phosphorus oxychloride is 200-3000.

[0015] Preferably, the mass concentration of the phosphorus-containing chain-extended polylactic acid in the shell spinning solution is 6-9%.

[0016] Preferably, the concentration ratio of the Mn(NO3)2 solution to the sodium hypochlorite solution is 1:6-7.

[0017] Preferably, the mass ratio of the phosphorus-containing chain-extended polylactic acid to Mn(NO3)2 in the Mn(NO3)2 solution is 16:1-1:1.

[0018] Preferably, the parameters during electrospinning are: voltage 9-14 kV, the flow rate ratio of the shell / core layer solution is 10:1, and the receiving distance is 10-15 cm.

[0019] Preferably, the hot pressing temperature is 115 °C.

[0020] The beneficial effects of the present invention are as follows: 1. By means of liquid phase deposition and double-layer electrospinning, MnO2 particles are prepared and directly deposited inside the hollow porous structure of the polylactic acid fiber. The polylactic acid fiber adsorbs volatile harmful gases and directly decomposes and desorbs the volatile harmful gases inside the hollow porous structure;

[0021] 2. The obtained hollow porous structure of the polylactic acid fiber can also be used as an excellent sound-absorbing material to reduce the transmission of external noise into the vehicle;

[0022] 3. The thermal decomposition temperature of polylactic acid fiber is 300 - 400 °C. As an in-vehicle heat insulation and sound insulation material, it has stable properties. After flame retardant modification, the LOI value is as high as 35%, and it is also convenient for spinning. Detailed implementation manners

[0023] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made. These all belong to the protection scope of the present invention.

[0024] Comparative example 1

[0025] Polylactic acid, molecular formula (C3H4O2) n , molecular weight M = 130000 g / mol, self-made; N, N - dimethylformamide (DMF), molecular formula (CH3)2NOCH, chloroform, purchased from Tianjin Kemiou Chemical Reagent Co., Ltd., analytical pure.

[0026] Weigh the measured PLA and dissolve it in chloroform; add it to DMF solvent systems with different ratios; stir at room temperature, in the dark, and under sealed conditions until the solute is completely dissolved, then ultrasonically remove bubbles for 30 min, and finally let it stand for 10 min for standby.

[0027] Draw the spinning solution with a syringe. The mass fraction of polylactic acid is 6 - 9%, and the mass ratio of chloroform to DMF is 11:1. After exhausting air bubbles, fix it on a micro - feeding pump, use a 20 - gauge needle, wrap the roller receiver with aluminum foil, rotate at 50 r / min, the receiving distance is 18 cm, the pushing speed is 0.003 mm / s, adjust the voltage to 9.0 kV, and then carry out spinning after the temperature and humidity environment inside the spinning machine box reach the preset values. After spinning, make sure to cut off the power supply, then remove the aluminum foil covering the fiber, dry it in an electric heating blast drying oven at 45 °C for 8 h, and then store it in a sealed manner.

[0028] SEM characterization: Remove the fiber membrane from the aluminum foil and dry it in a vacuum drying oven at 45 °C for 2 h, cut it into a suitable size and adhere it to the test bench, and observe the surface morphology of the fiber membrane by scanning electron microscopy after gold spraying. The average fiber diameter is 1265 - 1428 nm, the fiber is a hollow structure, and the surface has abundant micropores.

[0029] The hollow and porous polylactic acid fibers are fed into a carding machine by a cotton feeding machine for carding to form a fiber web, which is then conveyed to a lapping machine to be lapped into a fiber layer. The composite fibers are needled and reinforced on a needling machine. The semi-finished product after needling reinforcement is placed in a forming mold for molding. First, the upper mold is evacuated. The evacuation time is 20 seconds, and the pressure is 0.02 MPa. At the same time of evacuation, high-pressure steam is introduced. The vacuum degree is maintained, the steam pressure is 2 MPa, the temperature is 115 °C, the heating and forming pressure is 10 MPa, and the forming time is 40 s. Finally, it is cooled to room temperature to obtain an automotive sound insulation felt with a thickness of 1.5 mm.

[0030] The hollow and porous polylactic acid fibers are often used as raw materials for cigarette filters. They can adsorb harmful substances, are non-toxic and have high hydrophobicity. The hot-melted automotive sound insulation felt has adsorption ability and makes a certain contribution to the control of in-vehicle odors and VOCs, but its flame retardancy is not good. At present, bamboo charcoal is often used to adsorb volatile substances such as formaldehyde in the car, but the adsorption capacity is limited and it needs to be replaced frequently. The ability of the automotive sound insulation felt made of hollow and porous polylactic acid fibers to adsorb in-vehicle odors still needs to be improved.

[0031] In addition, the spinning parameters have a great influence on the morphology of the fibers.

[0032] During spinning, with the increase of temperature, it is beneficial to the volatilization of chloroform, and the pore coverage rate on the fiber surface increases. However, when the temperature exceeds 30 °C, the pore coverage rate on the fiber surface begins to decrease. During spinning, with the increase of humidity, the pore coverage rate on the fiber surface increases. When the humidity increases to more than 65%, the pore coverage rate on the fiber surface begins to decrease. The mass ratio of chloroform to DMF affects the normal progress of spinning. When the proportion of the solvent chloroform is too high, the jet flow cannot be completely volatilized immediately when flowing through the nozzle, and the proportion of the DMF solution with high conductivity is relatively low, and the conductivity of the spinning solution is relatively low, which is not conducive to spinning. When the mass ratio of chloroform / DMF is 5:1, there are fewer nano-porous structures on the fiber surface. When the mass ratio of chloroform / DMF is 13:1, the spinnability of the fiber is poor, and the spinning needle often clogs. Therefore, when the mass ratio of chloroform to DMF is 11:1, the pore coverage rate on the fiber surface is the best.

[0033] With the increase of the receiving distance, the average diameter of the fibers gradually decreases. When the receiving distance is 8 cm, the fiber diameter is relatively thick because the shorter receiving distance makes the stretching time of the jet flow in the fixed electric field interval shorter. With the gradual increase of the receiving distance, the stretching time and the total stretching force of the fibers in the electric field interval gradually increase, and the fiber diameter decreases accordingly. The average diameter of the fibers with a receiving distance of 24 cm is the smallest. When the receiving distance is 10 - 15 cm, the fiber diameter is moderate.

[0034] A lower voltage results in a smaller electric field force on the spinning solution, making it difficult to overcome the surface tension of the spinning solution and unable to form a stable "Taylor cone". As the voltage increases, the charge carried per unit volume of the spinning solution gradually increases, and the electric field stretching force and splitting ability of the jet in the electric field become larger, causing the spinning solution to be fully stretched and thinned. Considering all these factors, it is reasonable to set the spinning voltage parameter to 10.5 kV for preparing porous nanofibers.

[0035] Increasing the concentration of the spinning solution increases its viscosity and surface tension, weakening the splitting ability of the spinning solution in the electric field range and thickening the fiber diameter. When using a spinning solution with a mass percentage of 10%, the jet stability is poor, and solidification of the spinning solution occurs at the needle tip. Considering all these factors, it is reasonable to choose a spinning solution with a mass percentage of 6 - 9% for preparing porous nanofibers.

[0036] Example 1

[0037] (1) Synthesis of bis - end - capped lactic acid from polylactic acid

[0038] Weigh a certain amount of L - lactic acid raw material and add it to the reaction kettle. Under heating, stirring, and vacuum conditions, remove the moisture in the raw material. Subsequently, continue to raise the temperature to 140 °C, and gradually remove the moisture generated by the lactic acid condensation reaction during this period. Then add 1,4 - butanediol capping agent and stannous octoate catalyst according to 1 wt% and 0.5 wt% of the lactic acid mass, raise the temperature to 180 °C, and under vacuum (200 - 40 Pa) and vigorous stirring, the lactic acid undergoes condensation and end - hydroxylation reactions. After the acid value is less than 3, stop the reaction to obtain prepolymerized polylactic acid.

[0039]

[0040] (2) Chain - extension of prepolymerized polylactic acid

[0041] Add ethyl dichlorophosphine to the reaction system in step (1). After reacting at atmospheric pressure for 60 min, reduce the pressure to 40 Pa and react for 2 h to obtain the product phosphorus - containing chain - extended polylactic acid.

[0042]

[0043] To purify the phosphorus - containing chain - extended polylactic acid and remove the unreacted prepolymerized polylactic acid and ethyl dichlorophosphine, dissolve the obtained product in chloroform and then precipitate it in excess methanol. The same purification process is carried out twice to obtain purified PPLA. Finally, the product is dried in a vacuum oven at 60 °C until a constant weight is reached.

[0044] Flammability and combustibility were determined by the LOI test (JF-3 oxygen index instrument, Jiangning, China; using a plate size of 130 mm × 6.5 mm × 3 mm according to ASTM D2863-97), UL-94 measurement (Model CZF-2, Jiangning, China; using a plate size of 130 mm × 13 mm × 3 mm according to ASTM D3801), and cone calorimeter test (FTT cone calorimeter; irradiating a 100 mm × 100 mm × 6 mm square specimen with a heat flux of 35 kW / m 2 without using a "frame and grid" according to the ISO 5660 standard procedure). The micro combustion calorimeter test (MCC, FTT) was carried out according to ASTM D7309-07. All specimens used for various tests were hot-pressed at 170 °C under 10 MPa for 5 min to the appropriate thickness and size according to the corresponding test standards. By using a phosphorus-containing chain extender and through the chain extension reaction of prepolylactic acid, phosphorus was introduced into the main chain of polylactic acid, endowing polylactic acid with excellent flame retardant properties. The phosphorus-containing chain-extended polylactic acid has a very high flame retardant efficiency for polylactic acid. Compared with the LOI value of polylactic acid (LOI 20%) and UL-94 test (no grade), even when only 5% of PPLA was added to polylactic acid, FRPLA still had good flame retardant properties. When the PPLA content reached 10%, the LOI value of FRPLA could reach 34% and UL-94 V0 grade.

[0045] (3) Prepare the spinning solution

[0046] Dissolve the phosphorus-containing chain-extended polylactic acid in chloroform and then mix it into DMF. The mass ratio of chloroform to DMF is 11:1, and the mass concentration of the phosphorus-containing chain-extended polylactic acid in the shell spinning solution is 6% to prepare the shell spinning solution.

[0047] Prepare a 0.0769 mol / L Mn(NO3)2 solution and a 0.5037 mol / L NaClO solution, mix the two solutions, then pour in polyvinylpyrrolidone PVP, and dissolve it by mixing in DMF to prepare the core spinning solution;

[0048] (4) Electrospinning

[0049] The prepared shell spinning solution and core spinning solution are respectively injected into the outer needle and inner needle of a coaxial electrospinning needle. The inner and outer diameters of the inner needle of the coaxial spinning nozzle are 0.4 mm and 0.6 mm respectively. The inner diameter of the outer needle is 1.5 mm and the outer diameter is 3 mm. At the same time, an electrostatic generator is connected to the coaxial electrospinning needle for electrospinning, and a roller receiving device is used for receiving. The flow rate of the core layer solution is 0.2 ml / h, the flow rate of the shell layer solution is 2 ml / h, the voltage is 9 - 14 kV, the spinning distance is 15 cm, the ambient temperature is 25 ± 3 °C, and the humidity is 50 ± 5%. The as - spun fibers are obtained, and then the obtained as - spun fibers are immersed in deionized water at room temperature for more than 12 h, so that the PVP / DMF and sodium hypochlorite solution in the core layer dissolve in water to form hollow fibers. Then the hollow fibers after water bath are freeze - dried to obtain hollow porous phosphorus - containing chain - extended polylactic acid fibers loaded with MnO2 particles.

[0050] As the mass ratio of phosphorus - containing chain - extended polylactic acid to Mn(NO3)2 in the Mn(NO3)2 solution increases, the average fiber diameter decreases. However, no columnar structures are found on the fibers.

[0051] On the one hand, due to the appropriate spinning distance, the fiber diameter is relatively large, and the diameter of MnO2 particles does not exceed the fiber diameter, so no columnar structures are formed on the fibers. On the other hand, the phosphoryl groups in the phosphorus - containing chain - extended polylactic acid fibers are negatively charged, while Mn 4+ ions are positively charged. During electrospinning, under the action of the electric field, Mn 4+ ions approach the phosphoryl groups, and because the concentration of the Mn 4+ ion solution is low, the MnO2 particles are evenly dispersed in the phosphorus - containing chain - extended polylactic acid fibers without agglomeration to produce columnar structures.

[0052] Compared with other crystal forms of MnO2, γ - MnO2 has higher catalytic activity and better removal effect on volatile organic compounds such as formaldehyde. Using sodium chlorate to oxidize Mn 2+ deposited CMD is γ - MnO2, which has good electrochemical activity.

[0053] (5) Web forming and felting

[0054] The hollow porous phosphorus - containing chain - extended polylactic acid fibers loaded with MnO2 particles are fed into a carding machine for carding to form a fiber web, and then conveyed to a cotton laying machine to be laid into a fiber layer. The composite fibers are needled and reinforced on a needle punching machine. The semi - finished product after needle punching is placed in a forming mold for molding. First, the upper mold is evacuated, the evacuation time is 20 s, the pressure is 0.02 MPa, and high - pressure steam is introduced while evacuating; the vacuum degree is maintained, the steam pressure is 2 MPa, the temperature is 115 °C, the heating and forming pressure is 10 MPa, and the forming time is 40 s. Finally, it is cooled to room temperature to obtain an automotive sound - insulating felt with a thickness of 1.5 mm.

[0055] The method of this example was used to prepare automobile sound insulation felt, and when the loading amount of MnO2 on the phosphorus-containing extended chain polylactic acid fiber was 6.25%, the formaldehyde removal rate was tested.

[0056] Self-made 1m glass tube 3 The gas absorber is sealed and fixed at both ends with epoxy resin. The formaldehyde gas cylinder and the nitrogen gas cylinder are connected to the air inlet of the gas absorber through a pipe. A bubble absorption tube filled with 5 mL of absorption liquid is connected to the gas outlet of the gas absorber. A catheter is used to connect the peristaltic pump and the gas absorber so that water can be injected into the gas absorber. The gas in the gas absorber is discharged into the bubble absorption tube for gas sampling. One end of another catheter is connected to the gas absorber, and the other end is connected to a liquid flow meter so as to calculate the formaldehyde concentration in the gas absorber.

[0057] The formaldehyde concentration is detected by phenol reagent spectrophotometry (GB / T 18204.26-2000). The principle is as follows: formaldehyde in the air is absorbed by phenol reagent (3-methyl-benzothiazolone hydrazone), and condensation reaction generates azine, which is oxidized by ferric ions in an acidic solution to form a blue-green compound. The formaldehyde concentration in the sample gas can be determined by spectrophotometry.

[0058] 20g of the automobile sound insulation pad prepared in Example 1 was suspended in the gas absorber, and then both ends were sealed. Under the conditions of temperature of 25°C and humidity of 50%, 2.0mg / m 3 The formaldehyde gas is absorbed for a certain period of time, and then samples are taken through the bubble absorption tube to measure the formaldehyde concentration as the initial value.

[0059] Then, the formaldehyde concentration in the gas absorber and the formaldehyde removal efficiency of the car sound insulation pad were measured every hour. When the initial concentration in the gas absorber was 0.24 mg / m 3 and 0.96 mg / m 3 When , the formaldehyde purification rates after 2 hours were 95.2% and 86.5% respectively.

[0060] When it is detected that the formaldehyde in the gas absorber has been removed, the formaldehyde gas is repeatedly introduced to make the initial formaldehyde concentration in the gas absorber 0.24 mg / m 3 After waiting for 2 hours, re-sample and measure the formaldehyde concentration in the gas absorber. Repeat the experiment 20 times, and the formaldehyde purification rate remains above 95%.

Claims

1. A manufacturing method of an automotive sound insulation felt, characterized in that, It includes the following steps: The hollow porous phosphorus-containing chain-extended polylactic acid fiber loaded with MnO₂ particles is carded and web-laid to obtain a composite fiber, and the composite fiber is subjected to needling processing. Finally, the product after needling is hot-pressed and laminated to obtain an automotive sound insulation felt; The hollow porous phosphorus-containing chain-extended polylactic acid fiber loaded with MnO₂ particles is prepared through the following steps: (1) Add L-lactic acid to the reaction kettle, stir, heat and dehydrate under reduced pressure in a nitrogen atmosphere, and then add 1,4-butanediol and stannous chloride according to 1 wt% and 0.5 wt% of the mass of lactic acid. Heat up to 160-180 °C and react at 200-40 Pa until the acid value is less than 3, then stop the reaction to obtain prepolymerized lactic acid; (2) Charge the phosphoryl dichloride chain extender into the reaction kettle according to 50-200% of the molar amount of prepolymerized lactic acid, and react at 160-180 °C and 10-100 Pa for 0.5-3 h to obtain phosphorus-containing chain-extended polylactic acid; (3) Dissolve the phosphorus-containing chain-extended polylactic acid in chloroform and then mix it into DMF to prepare a shell spinning solution, and the mass ratio of chloroform to DMF is 5-11:

1. Then add sodium hypochlorite, an oxidant, to the Mn(NO₃)₂ solution, and then pour it into PVP and mix it in DMF to prepare a core spinning solution; (4) Inject the prepared shell spinning solution and core spinning solution into the outer needle and inner needle of a coaxial electrospinning needle respectively. At the same time, connect an electrostatic generator to the coaxial electrospinning needle for electrospinning, and use a roller receiving device to receive it to make a nascent fiber. Subsequently, soak the obtained nascent fiber in deionized water at room temperature for more than 12 h to dissolve the PVP / DMF and sodium hypochlorite solution in the core layer in water to form a hollow fiber, and then freeze-dry the hollow fiber after the water bath to obtain the hollow porous phosphorus-containing chain-extended polylactic acid fiber loaded with MnO₂ particles; The mass concentration of the phosphorus-containing chain-extended polylactic acid in the shell spinning solution is 6-9%, the concentration ratio of the Mn(NO₃)₂ solution to the sodium hypochlorite solution is 1:6-7, and the mass ratio of the phosphorus-containing chain-extended polylactic acid to Mn(NO₃)₂ in the Mn(NO₃)₂ solution is 16:1-1:1; The parameters during electrospinning are: voltage 9-14 kV, the flow rate ratio of the shell / core layer solution is 10:1, and the receiving distance is 10-15 cm; The molecular weight of the phosphorus-containing chain-extended polylactic acid is 1000-10000; The phosphoryl dichloride chain extender is monomolecular phosphoryl dichloride or oligomeric phosphoryl dichloride, and the molecular weight of the oligomeric phosphoryl dichloride is 200-3000; The hot-pressing temperature is 115 °C.

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