Preparation method of degradable multi-scale PLA superfine fiber air filtering membrane

Abstract

The invention discloses a preparation method of a degradable multi-scale PLA superfine fiber air filtering membrane, which comprises the following steps: dissolving organic salt powder in a DMC / DMF mixed solvent, stirring, adding PLA powder, stirring again, respectively preparing a spinning solution a and a spinning solution b, depositing superfine fibers with different sizes on a receiving roller by a counter-jet spinning machine, and preparing the degradable multi-scale PLA superfine fiber air filtering membrane. A multi-scale fiber accumulation body structure can be constructed, so that the integrated multi-scale composite nano fiber net has the characteristics of high efficiency, low resistance, stable filtering performance and high filtering precision, and the defect that the air filtering effect and the air filtering resistance are difficult to balance in the prior art is overcome; the filtering membrane is formed by uniformly blending spinning solution b spinning fibers with the fiber diameter of 10-100 nm and spinning solution a spinning fibers with the fiber diameter of 200-500 nm, the spinning solution a spinning fibers intercept large-particle pollutants, the spinning solution b spinning fibers intercept small-size particles, high filtering efficiency is provided, low resistance is kept, the dust holding capacity is improved, and the service life is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of air filtration membranes, and in particular to a method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane. Background Art

[0002] With the rapid development of society, people's living standards have been greatly improved, but air pollution has become increasingly serious. In many countries around the world, different degrees of air pollution have occurred. Blocking the haze virus from invading the human body has become a problem that needs to be solved urgently around the world. Against this background, the use of non-woven disposable masks has surged. The core material of the current mask is polypropylene melt-blown non-woven fabric derived from petrochemical products. A large amount of solid waste from used masks has exacerbated plastic pollution. These materials naturally degrade over hundreds of years and may be converted into microplastic particles that harm the entire earth's ecosystem. Melt-blown non-woven materials effectively capture ultrafine particles through electrostatic adsorption, and the material itself carries a large amount of static charge. However, the electrostatic adsorption related to charge dissipation in humid human breathing is weakened, resulting in a rapid decay in the filtration efficiency of the melt-blown material, and a shortened validity period leads to frequent replacement of masks, which further increases usage.

[0003] Nanofiber materials are widely used in the field of air filtration due to their thin diameter, large specific surface area, small pore size, high porosity, and easy modification. As the most commonly used technology for preparing nanofibers, electrospinning has a wide range of spinnable raw materials, strong structural adjustability, good integration of multiple technologies, strong expansibility of preparation processes, and has gradually approached the industrialization stage. It has become one of the main ways to effectively prepare nanofiber high-efficiency filtration materials. Although electrospun nanofibers have many advantages, in the field of air filtration, in order to achieve an ideal filtration efficiency, for nanofibers of a single size, it can only be achieved by increasing the fiber thickness and stacking density, but the resistance pressure drop will increase linearly, resulting in no obvious advantage compared to the filtration performance of traditional filter materials.

[0004] Therefore, it is necessary to improve the nanofiber filtration membrane in the prior art to solve the above problems. Summary of the invention

[0005] The invention overcomes the shortcomings of the prior art and provides a method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane, comprising the following steps:

[0007] S1: adding organic salt powder a and PLA powder to a DMC / DMF mixed solvent successively, wherein the concentration of the organic salt powder is 0-5 mg / ml, the mass ratio of DMC / DMF is 9:1-1:9, and the organic salt powder a and PLA powder are stirred during the addition process to obtain a spinning solution a with a PLA concentration of 90-120 mg / ml;

[0008] S2: adding organic salt powder b and PLA powder to DMC / DMF mixed solvent successively, the organic salt powder concentration is 40-80 mg / ml, the DMC / DMF mass ratio is 5:5, and the organic salt powder b and PLA powder are stirred during the addition process to obtain a spinning solution b with a PLA concentration of 30-70 mg / ml;

[0009] S3: The spinning solution a in S1 and the spinning solution b in S2 are respectively spun simultaneously using a jet spinning machine, wherein the diameter of the fiber spun from one end of the spinning solution a is 200-500 nm, and the diameter of the fiber spun from one end of the spinning solution b is 10-100 nm, and the spun fibers are deposited on the upper surface of the base fabric of the receiving roller, and the spinning time is 0.5-10 min to obtain a spun deposition film;

[0010] S4: placing the spun deposited membrane in S3 into a vacuum oven and drying it for 1-2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0011] In a preferred embodiment of the present invention, the organic powder a and the organic powder b are respectively one or more of trimethylammonium chloride, trimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and hexadecyltrimethylammonium bromide.

[0012] In a preferred embodiment of the present invention, the organic powder a and the organic powder b are both trimethylammonium chloride.

[0013] In a preferred embodiment of the present invention, the stirring conditions of the organic salt powder a are stirring at a temperature of 40-60°C and a rotation speed of 100-300 r / min for 1 hour, and the stirring conditions of the organic salt powder b are stirring at a temperature of 40-60°C and a rotation speed of 100-300 r / min for 3 hours.

[0014] In a preferred embodiment of the present invention, the PLA powder in S1 and S2 is stirred at a temperature of 60-80° C. and a rotation speed of 200-400 r / min for 4-8 hours.

[0015] In a preferred embodiment of the present invention, the spinning parameters of the spinning solution a in S3 are: spinning voltage 25-30kV, liquid injection rate 0.5-1.0ml / h, receiving distance 15-20cm, receiving roller speed 20-60r / min, spinning temperature 25±3℃, relative humidity 30±3%.

[0016] In a preferred embodiment of the present invention, the spinning parameters of the spinning solution b in S3 are: spinning voltage 30-35kV, liquid injection rate 0.4-0.8ml / h, receiving distance 25-30cm, receiving roller speed 20-60r / min, spinning temperature 25±3℃, relative humidity 30±3%.

[0017] In a preferred embodiment of the present invention, the spinning time is 3 minutes.

[0018] In a preferred embodiment of the present invention, the base fabric is a PLA spunbonded nonwoven fabric.

[0019] To achieve the above-mentioned purpose, the second technical solution adopted by the present invention is: a degradable multi-scale PLA ultrafine fiber air filter membrane, which is prepared based on a preparation method of a degradable multi-scale PLA ultrafine fiber air filter membrane.

[0020] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0021] (1) The present invention provides a method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane, comprising the steps of dissolving an organic salt powder in a DMC / DMF mixed solvent and stirring the mixture, adding PLA powder and stirring the mixture again, and preparing spinning liquid a and spinning liquid b respectively. Ultrafine fibers of different sizes are deposited on a receiving roller by a counter-spinning machine. Compared with the air filtration membrane in the prior art, a multi-scale fiber stacking structure can be constructed, so that the multi-scale composite nanofiber web combined into a whole has the characteristics of high efficiency and low resistance, stable filtration performance and high filtration accuracy, thereby solving the defect in the prior art that it is difficult to balance the air filtration effect and the air filtration resistance.

[0022] (2) In the present invention, the organic salt powder a and the organic salt powder b are stirred at a temperature of 40-60° C. and a rotation speed of 100-300 r / min for 1 h and 3 h, respectively, and the PLA powder is stirred at a temperature of 60-80° C. and a rotation speed of 200-400 r / min for 4-8 h, so that the organic salt powder a, the organic salt powder b and the PLA powder are respectively evenly dispersed in the solvent, which improves the conductivity of the solution without affecting the solubility of the polymer. Compared with the prior art, the spinning is stable, the fiber uniformity is high, and the stable fiber membrane structure ensures the neat structure of the filter membrane, so that the filter membrane has long-term stable filtration performance.

[0023] (3) In the present invention, the filter membrane is composed of a uniform blend of fibers spun from spinning solution b with a fiber diameter of 10-100nm and fibers spun from spinning solution a with a fiber diameter of 200-500nm. The fibers spun from spinning solution a intercept large particles of pollutants, and the fibers spun from spinning solution b intercept smaller particles. The coarse and fine fibers are graded and combined. Compared with the prior art, the filter membrane provides high filtration efficiency while maintaining low resistance, thereby achieving high-efficiency and low-resistance filtration, increasing dust holding capacity and extending service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 is a method step diagram of a preferred embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of a jet spinning machine according to a preferred embodiment of the present invention;

[0027] Figure 3 is a fiber SEM image of spinning solution a of Example 1 of a preferred embodiment of the present invention;

[0028] Figure 4 This is a small-magnification SEM image of a PLA nanofiber membrane / PLA nonwoven fabric substrate of a preferred embodiment of the present invention;

[0029] Figure 5 This is a SEM image of a multi-scale fiber membrane of Example 3 of a preferred embodiment of the present invention;

[0030] Figure 6 This is a SEM image of a multi-scale fiber membrane of Example 8 of a preferred embodiment of the present invention;

[0031] Figure 7 is a graph showing the filtration performance of a PLA fiber membrane at different spinning times in Example 8 of a preferred embodiment of the present invention;

[0032] Figure 8 This is a SEM image of a multi-scale fiber membrane of Example 9 of a preferred embodiment of the present invention;

[0033] Fig. 9 It is a fiber filtration performance diagram of the fiber SEM of Example 1, Example 2 and Example 8 with a spinning time of 3.0 min of the preferred embodiment of the present invention;

[0034] In the figure: 1. Spinning solution a syringe; 2. Spinning solution b syringe; 3. Push injection device; 4. Receiving roller; 5. Screw guide rail. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0037] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0038] like Figure 1 As shown, a method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane comprises the following steps:

[0039] S1: adding organic salt powder a and PLA powder to a DMC / DMF mixed solvent successively, wherein the concentration of the organic salt powder is 0-5 mg / ml, the mass ratio of DMC / DMF is 9:1-1:9, and the organic salt powder a and PLA powder are stirred during the addition process to obtain a spinning solution a with a PLA concentration of 90-120 mg / ml;

[0040] The organic powder a and the organic powder b are respectively one or more of trimethylammonium chloride, trimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

[0041] As a preferred embodiment, the organic powder a and the organic powder b are both trimethylammonium chloride.

[0042] S2: adding organic salt powder b and PLA powder to DMC / DMF mixed solvent successively, the organic salt powder concentration is 40-80 mg / ml, the DMC / DMF mass ratio is 5:5, and the organic salt powder b and PLA powder are stirred during the addition process to obtain a spinning solution b with a PLA concentration of 30-70 mg / ml;

[0043] The stirring conditions of the organic salt powder a are stirring at a temperature of 40-60° C. and a rotation speed of 100-300 r / min for 1 hour, and the stirring conditions of the organic salt powder b are stirring at a temperature of 40-60° C. and a rotation speed of 100-300 r / min for 3 hours.

[0044] The stirring conditions of PLA powder in S1 and S2 are 60-80°C and 200-400r / min for 4-8h. The uniform fiber distribution and stable fiber structure ensure the long-term stable filtration performance of the filter membrane.

[0045] S3: Spinning solution a in S1 and spinning solution b in S2 are spun simultaneously using a jet spinning machine, wherein the diameter of the fiber spun from one end of the spinning solution a is 200-500 nm, and the diameter of the fiber spun from one end of the spinning solution b is 10-100 nm, and the spun fibers are deposited on the upper surface of the base fabric of the receiving roller, and the spinning time is 0.5-10 min to obtain a spun deposition film;

[0046] The spinning parameters of the spinning solution a in S3 are: spinning voltage 25-30 kV, liquid injection rate 0.5-1.0 ml / h, receiving distance 15-20 cm, receiving roller speed 20-60 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0047] The spinning parameters of the spinning solution b in S3 are: spinning voltage 30-35 kV, liquid injection rate 0.4-0.8 ml / h, receiving distance 25-30 cm, receiving roller speed 20-60 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0048] The spinning time is 3 minutes. The spinning time can accurately control the amount of fiber deposition on the base fabric, ensure the thickness and uniformity of the fiber layer, and thus affect the filtration efficiency and air permeability of the filter membrane. Appropriate spinning time can reduce fiber breakage and defects during the formation process and improve the mechanical strength and durability of the filter membrane.

[0049] The base fabric is PLA spunbond nonwoven fabric. PLA is a biodegradable polymer. Using PLA spunbond nonwoven fabric as the base fabric makes the entire filter membrane biodegradable and environmentally friendly. Both the base fabric and the fiber are made of PLA material, which ensures the consistency of the material and helps to improve the overall performance and stability of the filter membrane. The porous structure of the nonwoven fabric is conducive to air circulation. Using PLA spunbond nonwoven fabric as the base fabric can ensure that the filter membrane has good air permeability and reduce air flow resistance.

[0050] S4: The spun deposited membrane in S3 is placed in a vacuum oven and dried for 1-2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0051] The organic salt powder is dissolved in the DMC / DMF mixed solvent and stirred, and then the PLA powder is added and stirred again. The spinning liquid a and the spinning liquid b prepared respectively are deposited on the receiving roller by a jet spinning machine to deposit ultrafine fibers of different sizes. A multi-scale fiber stack structure can be constructed, so that the multi-scale composite nanofiber web combined into a whole has the characteristics of high efficiency and low resistance, stable filtration performance and high filtration accuracy, which solves the defect of the prior art that it is difficult to balance the air filtration effect and air filtration resistance.

[0052] Precise control of the jet spinning machine can reduce fiber breakage during deposition and improve the overall quality and performance of the filter membrane. The rotation of the receiving drum helps to evenly distribute the fibers on the drum surface and avoid excessive concentration of fiber deposition, thereby improving the uniformity and consistency of the filter membrane. The rotation of the drum can guide the fibers to orient in a specific direction to form an orderly fiber structure, which helps to improve the mechanical properties and filtration efficiency of the filter membrane.

[0053] The rotation of the drum can reduce the adhesion between fibers, because the fibers will be dispersed by the rotation of the drum during the deposition process, which helps to maintain the air permeability and filtration performance of the filter membrane. The rotation of the drum helps to form a smooth filter membrane surface and improve the surface filtration performance. The drum speed affects the degree of stretching of the fibers during the deposition process. A higher drum speed can increase the stretching of the fibers, help to form finer fibers, and improve the filtration accuracy.

[0054] To achieve the above-mentioned purpose, the second technical solution adopted by the present invention is: a degradable multi-scale PLA ultrafine fiber air filter membrane, which is prepared based on a preparation method of a degradable multi-scale PLA ultrafine fiber air filter membrane.

[0055] like Figure 2As shown, when spinning is carried out, the receiving roller 4 is located between the spinning liquid a injector 1 and the spinning liquid b injector 2, and the spinning liquid a injector 1 and the spinning liquid b injector 2 are respectively fixedly connected with a push injection device 3 and a screw guide rail 5, the push injection device 3 is used to provide power to the spinning liquid a injector 1 and the spinning liquid b injector 2, and the screw guide rail 5 is used to adjust the distance between the spinning liquid a injector 1 and the spinning liquid b injector 2 and the receiving roller 4.

[0056] Example 1

[0057] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0058] S1: In a fume hood, 200 mg of trimethylammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and the mixture was stirred at 60°C and 200 r / min for 1 h to dissolve the trimethylammonium chloride powder. Then 9 g of PLA powder was added to the solution, and the mixture was stirred at 60°C and 200 r / min for 8 h to prepare a 90 mg / ml PLA spinning solution a.

[0059] S2: The syringes on both sides of the spinning equipment were filled with spinning solution a, and PLA spunbond nonwoven fabric was used as the receiving substrate to prepare PLA fiber membrane. Spinning parameters: spinning voltage 25kV, liquid injection rate 0.5ml / h, receiving distance 20cm, receiving drum speed 30r / min, spinning temperature 25±3℃, relative humidity 30±3%. The fiber membrane obtained by spinning for 4min was placed in a vacuum oven and dried for 2h to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0060] The prepared fiber membrane was observed by Phenom Pure (Pw-100-515) desktop electron microscope. Figure 3 , and the filtration performance of the prepared fiber membrane was tested using TSI8130a. The samples need to be processed before the test: soak the samples in isopropanol for 30 minutes, dry them naturally, and then place them in a 60℃ oven to dry for 30 minutes. The test conditions are: the test medium is NaCl particles (average particle size 0.3μm), and the air flow rate is 32L / min.

[0061] Example 2

[0062] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0063] S1: In a fume hood, add 4 g of trimethylammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir for 3 h at 60°C and 200 r / min to fully dissolve. Then add 7 g of PLA powder to the mixed solution, and stir for 8 h at 60°C and 400 r / min to prepare a spinning solution b with a PLA concentration of 70 mg / ml.

[0064] S2: The spinning solution b is respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning parameters are spinning voltage 35kV, liquid injection rate 0.5ml / h, receiving distance 25cm, receiving roller speed 30r / min, spinning temperature 25±3℃, relative humidity 30±3%. The fiber membrane obtained by spinning for 4min is placed in a vacuum oven and dried for 2h.

[0065] Example 3

[0066] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0067] S1: In a fume hood, 50 mg of trimethylammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stirred at 60°C and 200 r / min for 1 h to dissolve the trimethylammonium chloride powder. Then 12 g of PLA powder was added to the solution, and stirred at 60°C and 200 r / min for 8 h to prepare a 90 mg / ml PLA spinning solution a.

[0068] S2: In a fume hood, 4 g of trimethylammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stirred at 60°C and 200 r / min for 3 h to fully dissolve. Then 7 g of PLA powder was added to the mixed solution, and stirred at 60°C and 400 r / min for 8 h to prepare a spinning solution b with a PLA concentration of 70 mg / ml.

[0069] S3: The spinning solution a and the spinning solution b are respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning conditions on both sides are as follows:

[0070] The spinning parameters of spinning solution a are as follows: spinning voltage 25 kV, liquid injection rate 0.5 ml / h, receiving distance 20 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0071] The spinning parameters of the spinning solution b are as follows: spinning voltage 35 kV, liquid injection rate 0.5 ml / h, receiving distance 25 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0072] S4: After spinning for 4 minutes, the obtained fiber membrane is placed in a vacuum oven and dried for 2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0073] like Figure 4 and Figure 5 As shown, the microscopic morphology of the PLA nanofiber membrane / PLA non-woven fabric substrate and the prepared fiber membrane were observed respectively using a Phenom Pure (Pw-100-515) desktop electron microscope.

[0074] The samples need to be processed before testing: soak the samples in isopropanol for 30 minutes, dry them naturally, and then dry them in a 60°C oven for 30 minutes. The test conditions are: the test medium is NaCl particles (average particle size 0.3μm), and the air flow rate is 32L / min.

[0075] Example 4

[0076] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0077] S1: In a fume hood, 100 mg of trimethylammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and the mixture was stirred at 60°C and 200 r / min for 1 h to dissolve the trimethylammonium chloride powder. Then 12 g of PLA powder was added to the solution, and the mixture was stirred at 60°C and 200 r / min for 8 h to prepare a 90 mg / ml PLA spinning solution a.

[0078] S2: In a fume hood, add 5 g of trimethylammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir for 3 h at 60°C and 200 r / min to fully dissolve. Then add 7 g of PLA powder to the mixed solution, stir for 8 h at 60°C and 400 r / min to prepare a spinning solution b with a PLA concentration of 70 mg / ml.

[0079] S3: The spinning solution a and the spinning solution b are respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning conditions on both sides are as follows:

[0080] The spinning parameters of spinning solution a are as follows: spinning voltage 25 kV, liquid injection rate 0.5 ml / h, receiving distance 20 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0081] The spinning parameters of the spinning solution b are as follows: spinning voltage 35 kV, liquid injection rate 0.5 ml / h, receiving distance 25 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0082] S4: After spinning for 4 minutes, the obtained fiber membrane is placed in a vacuum oven and dried for 2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0083] Example 5

[0084] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0085] S1: In a fume hood, 200 mg of trimethylammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and the mixture was stirred at 60°C and 200 r / min for 1 h to dissolve the trimethylammonium chloride powder. Then 12 g of PLA powder was added to the solution, and the mixture was stirred at 60°C and 200 r / min for 8 h to prepare a 90 mg / ml PLA spinning solution a.

[0086] S2: In a fume hood, add 5 g of trimethylammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir for 3 h at 60°C and 200 r / min to fully dissolve. Then add 7 g of PLA powder to the mixed solution, stir for 8 h at 60°C and 400 r / min to prepare a spinning solution b with a PLA concentration of 70 mg / ml.

[0087] S3: The spinning solution a and the spinning solution b are respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning conditions on both sides are as follows:

[0088] The spinning parameters of spinning solution a are as follows: spinning voltage 25 kV, liquid injection rate 0.5 ml / h, receiving distance 20 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0089] The spinning parameters of the spinning solution b are as follows: spinning voltage 35 kV, liquid injection rate 0.5 ml / h, receiving distance 25 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0090] S4: After spinning for 4 minutes, the obtained fiber membrane is placed in a vacuum oven and dried for 2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0091] Example 6

[0092] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0093] S1: In a fume hood, 300 mg of trimethylammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and the mixture was stirred at 60°C and 200 r / min for 1 h to dissolve the trimethylammonium chloride powder. Then 12 g of PLA powder was added to the solution, and the mixture was stirred at 60°C and 200 r / min for 8 h to prepare a 90 mg / ml PLA spinning solution a.

[0094] S2: In a fume hood, add 5 g of trimethylammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir for 3 h at 60°C and 200 r / min to fully dissolve. Then add 7 g of PLA powder to the mixed solution, stir for 8 h at 60°C and 400 r / min to prepare a spinning solution b with a PLA concentration of 70 mg / ml.

[0095] S3: The spinning solution a and the spinning solution b are respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning conditions on both sides are as follows:

[0096] The spinning parameters of spinning solution a are as follows: spinning voltage 25 kV, liquid injection rate 0.5 ml / h, receiving distance 20 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0097] The spinning parameters of the spinning solution b are as follows: spinning voltage 35 kV, liquid injection rate 0.5 ml / h, receiving distance 25 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0098] S4: After spinning for 4 minutes, the obtained fiber membrane is placed in a vacuum oven and dried for 1-2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0099] Example 7

[0100] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0101] S1: In a fume hood, 100 mg of tetradecyl trimethyl ammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stirred at 60°C and 200 r / min for 1 h to dissolve the tetradecyl trimethyl ammonium chloride powder. Then 12 g of PLA powder was added to the solution, and stirred at 60°C and 200 r / min for 8 h to prepare a 90 mg / ml PLA spinning solution a.

[0102] S2: In a fume hood, add 5 g of tetradecyl trimethyl ammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir for 3 h at 60°C and 200 r / min to fully dissolve. Then add 7 g of PLA powder to the mixed solution, stir for 8 h at 60°C and 400 r / min to prepare a spinning solution b with a PLA concentration of 70 mg / ml.

[0103] S3: The spinning solution a and the spinning solution b are respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning conditions on both sides are as follows:

[0104] The spinning parameters of spinning solution a are as follows: spinning voltage 25 kV, liquid injection rate 0.5 ml / h, receiving distance 20 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0105] The spinning parameters of the spinning solution b are as follows: spinning voltage 35 kV, liquid injection rate 0.5 ml / h, receiving distance 25 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

[0106] S4: After spinning for 4 minutes, the obtained fiber membrane is placed in a vacuum oven and dried for 2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0107] Example 8

[0108] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0109] S1: In a fume hood, 200 mg of trimethylammonium chloride powder was added to 100 ml of a mixed solvent of DMC / DMF = 1:1, and the mixture was stirred at 60°C and 200 r / min for 1 h to dissolve the trimethylammonium chloride powder. Then 9 g of PLA powder was added to the solution, and the mixture was stirred at 60°C and 200 r / min for 8 h to prepare a spinning solution a of 90 mg / ml.

[0110] S2: In a fume hood, add 6 g of trimethylammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir for 3 h at 60°C and 200 r / min to fully dissolve. Then add 6 g of PLA powder to the mixed solution, stir for 8 h at 60°C and 400 r / min to prepare a spinning solution b with a PLA concentration of 60 mg / ml.

[0111] S3: The spinning solution a and the spinning solution b are respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning conditions on both sides are as follows:

[0112] Spinning parameters of spinning solution a: Spinning parameters: spinning voltage 25 kV, liquid injection rate 0.5 ml / h, receiving distance 20 cm, receiving drum speed 30 r / min, spinning temperature 25±3°C, relative humidity 30±3%.

[0113] Spinning parameters of spinning solution b: spinning voltage 35 kV, liquid injection rate 0.5 ml / h, receiving distance 25 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., relative humidity 30±3%.

[0114] S4: The spinning process is performed with spinning times of 0.5 min, 1.0 min, 1.5 min, 2.0 min, 2.5 min, 3.0 min, 3.5 min, 4.0 min and 4.5 min respectively. The obtained fiber membrane is placed in a vacuum oven and dried for 1-2 h to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0115] The prepared fiber membrane was observed by Phenom Pure (Pw-100-515) desktop electron microscope. Figure 6 The filtration performance of the prepared fiber membrane was tested using TSI8130a. The results are as follows: Figure 7 As shown in the figure, when the spinning time is 3.0min, the filtration efficiency is nearly 100%, and the filtration resistance is less than 50%, so the spinning time of 3.0min is the best spinning time. The sample needs to be processed before the test: soak the sample in isopropanol for 30min, dry it naturally, and then place it in a 60℃ oven to dry for 30min. The test medium is NaCl particles (average particle size 0.3μm), and the air flow rate is 32L / min.

[0116] Example 9

[0117] This example prepares a degradable multi-scale PLA ultrafine fiber air filtration membrane, and the preparation process is as follows:

[0118] S1: In a fume hood, add 200 mg of trimethylammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir at 60°C and 200 r / min for 1 h to dissolve the trimethylammonium chloride powder. Then add 10 g of PLA powder to the solution, stir at 60°C and 200 r / min for 4-8 h to prepare a spinning solution a of 90 mg / ml.

[0119] S2: In a fume hood, add 8 g of trimethylammonium chloride powder to 100 ml of a mixed solvent of DMC / DMF = 1:1, and stir for 3 h at 60°C and 200 r / min to fully dissolve. Then add 6 g of PLA powder to the mixed solution, and stir for 8 h at 60°C and 400 r / min to prepare a spinning solution b with a PLA concentration of 60 mg / ml.

[0120] S3: The spinning solution a and the spinning solution b are respectively loaded into the syringes on both sides of the jet electrospinning device for spinning, and the two fibers are spun onto the PAL non-woven fabric on the same receiving roller. The spinning conditions on both sides are as follows:

[0121] Spinning parameters of spinning solution a: Spinning parameters: spinning voltage 25 kV, liquid injection rate 0.5 ml / h, receiving distance 20 cm, receiving drum speed 30 r / min, spinning temperature 25±3°C, relative humidity 30±3%.

[0122] Spinning parameters of spinning solution b: spinning voltage 35 kV, liquid injection rate 0.5 ml / h, receiving distance 25 cm, receiving drum speed 30 r / min, spinning temperature 25±3° C., relative humidity 30±3%.

[0123] S4: After spinning for 4 minutes, the obtained fiber membrane is placed in a vacuum oven and dried for 2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

[0124] The prepared fiber membrane was observed by Phenom Pure (Pw-100-515) desktop electron microscope. Figure 8 .

[0125] like Fig. 9 As shown, the filtration efficiency and filtration resistance of Example 1 are relatively low, the filtration efficiency and filtration resistance of Example 3 are relatively high, and the filtration efficiency of Example 8 is higher and the filtration resistance is lower, which is better than other examples. Example 8 with a spinning time of 3.0 min is the optimal example.

[0126] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane, characterized in that: The following steps are involved: S1: adding organic salt powder a and PLA powder to a DMC / DMF mixed solvent successively, wherein the concentration of the organic salt powder is 0-5 mg / ml, the mass ratio of DMC / DMF is 9:1-1:9, and the organic salt powder a and PLA powder are stirred during the addition process to obtain a spinning solution a with a PLA concentration of 90-120 mg / ml; S2: adding organic salt powder b and PLA powder to DMC / DMF mixed solvent successively, the organic salt powder concentration is 40-80 mg / ml, the DMC / DMF mass ratio is 5:5, and the organic salt powder b and PLA powder are stirred during the addition process to obtain a spinning solution b with a PLA concentration of 30-70 mg / ml; S3: The spinning solution a in S1 and the spinning solution b in S2 are respectively spun simultaneously using a jet spinning machine, wherein the diameter of the fiber spun from one end of the spinning solution a is 200-500 nm, and the diameter of the fiber spun from one end of the spinning solution b is 10-100 nm, and the spun fibers are deposited on the upper surface of the base fabric of the receiving roller, and the spinning time is 0.5-10 min to obtain a spun deposition film; S4: placing the spun deposited membrane in S3 into a vacuum oven and drying it for 1-2 hours to obtain a degradable multi-scale PLA ultrafine fiber air filtration membrane.

2. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 1, characterized in that: The organic powder a and the organic powder b are respectively one or more of trimethylammonium chloride, trimethylammonium bromide, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

3. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 2, characterized in that: The organic powder a and the organic powder b are both trimethylammonium chloride.

4. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 1, characterized in that: The stirring conditions of the organic salt powder a are stirring at a temperature of 40-60° C. and a rotation speed of 100-300 r / min for 1 hour, and the stirring conditions of the organic salt powder b are stirring at a temperature of 40-60° C. and a rotation speed of 100-300 r / min for 3 hours.

5. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 1, characterized in that: The stirring conditions of the PLA powder in the S1 and the S2 are stirring at a temperature of 60-80° C. and a rotation speed of 200-400 r / min for 4-8 hours.

6. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 1, characterized in that: The spinning parameters of the spinning solution a in S3 are: spinning voltage 25-30 kV, liquid injection rate 0.5-1.0 ml / h, receiving distance 15-20 cm, receiving roller speed 20-60 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

7. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 1, characterized in that: The spinning parameters of the spinning solution b in S3 are: spinning voltage 30-35 kV, liquid injection rate 0.4-0.8 ml / h, receiving distance 25-30 cm, receiving roller speed 20-60 r / min, spinning temperature 25±3° C., and relative humidity 30±3%.

8. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 1, characterized in that: The spinning time is 3 minutes.

9. The method for preparing a degradable multi-scale PLA ultrafine fiber air filtration membrane according to claim 1, characterized in that: The base fabric is PLA spunbonded nonwoven fabric.

10. A degradable multi-scale PLA ultrafine fiber air filtration membrane, characterized in that: It is prepared based on the preparation method of a degradable multi-scale PLA ultrafine fiber air filtration membrane according to any one of claims 1-9.

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