Degradable fiber composite filter material and preparation method thereof

Abstract

The invention provides a degradable fiber composite filter material and a preparation method thereof, and belongs to the technical field of degradable materials. The preparation method comprises the following steps: firstly, modifying PPC-P by adopting a macromolecular antibacterial agent to obtain MPPC-P, and carrying out melt spinning on the MPPC-P and hydrophobic modified nano titanium dioxide to obtain antibacterial hydrophobic spun-bonded fibers; then, PPC-P and a dichloromethane acetone solution of a polymer antibacterial agent are adopted for electrostatic spinning to obtain electrostatic spinning antibacterial nanofibers, and then the antibacterial hydrophobic spun-bonded fibers and the electrostatic spinning antibacterial nanofibers serve as raw materials; and preparing the degradable fiber composite filter material according to the sequence of the antibacterial hydrophobic spun-bonded fibers, the electrostatic spinning antibacterial nanofibers and the antibacterial hydrophobic spun-bonded fibers. The degradable fiber composite filtering material prepared by the invention has a good filtering effect, a super-hydrophobic function, lasting antibacterial performance, complete biodegradability and environmental protection performance.

Description

Technical Field

[0001] The present invention relates to the technical field of degradable materials, and particularly relates to a degradable fiber composite filter material and a preparation method thereof. Background Art

[0002] Currently, commonly used products such as medical and sanitary care non-woven fabrics, non-woven fabrics for air filtration and purification, and disposable daily necessities non-woven fabrics are usually made of polypropylene, nylon, polyethylene, etc. synthesized from petroleum raw materials. The above materials are not biodegradable, have low hydrophobicity, are prone to moisture absorption causing fiber pore blockage, poor air permeability, and a degradation period of more than 50 years. They not only consume petroleum resources but also easily cause environmental pollution after use and discard. At the same time, the products made of such materials do not have antibacterial properties themselves and are prone to bacterial growth during use.

[0003] Polylactic acid is a potential material that is currently being vigorously developed to replace polypropylene, but its raw materials are made by grain fermentation, with limited sources and high prices.

[0004] PPC-P is a polyester material synthesized from carbon dioxide as a raw material with propylene oxide and phthalic anhydride. The mass ratio of carbon dioxide in the material exceeds 40%. It not only consumes the greenhouse gas carbon dioxide but also can be completely biodegradable after use. It has a lower cost compared to PLA and is one of the potential polypropylene alternative materials that can be used on a large scale in the future. Summary of the Invention

[0005] In view of this, the present invention provides a preparation method of a degradable fiber composite filter material. The material prepared by this method consists of a three-layer composite structure and has filtering function, superhydrophobic function, persistent antibacterial property, and biodegradable property.

[0006] The preparation method of the degradable fiber composite filter material in the present invention includes the following steps:

[0007] (1) PPC-P modification: Dry PPC-P, then mix it evenly with a polymer antibacterial agent, and perform melt blending, extrusion, cooling, and pelletizing to obtain modified PPC-P spinning raw material (MPPC-P);

[0008] The specific structure of the PPC-P is as shown in formula (1), and the structure of the polymer antibacterial agent is as shown in formula (2):

[0009]

[0010]

[0011] (2) Manufacturing of antibacterial hydrophobic spunbond fibers: After uniformly mixing MPPC-P and hydrophobically modified nano-titanium dioxide, melt spinning is carried out to obtain antibacterial hydrophobic spunbond fibers;

[0012] (3) Manufacturing of electrospun antibacterial nanofibers: Mix PPC-P and a polymer antibacterial agent, add them to a mixed solvent of dichloromethane and acetone to obtain a spinning solution with a concentration of 5-10 wt%, and then carry out electrospinning using the spinning solution to obtain electrospun antibacterial nanofibers;

[0013] (4) Lay and stack antibacterial hydrophobic spunbond fibers, electrospun antibacterial nanofibers, and antibacterial hydrophobic spunbond fibers from bottom to top, and then use a roller for hot pressing to obtain the degradable fiber composite filter material.

[0014] Preferably, the drying temperature in step (1) is 50-70 °C, and the drying time is 5-8 h.

[0015] Preferably, the mass ratio of PPC-P to the polymer antibacterial agent in step (1) is 100:0.5-10.

[0016] Preferably, the feeding section temperature of the melt blending in step (1) is 35-50 °C, the melt blending section temperature is 150-200 °C, and the die temperature at the extrusion port is 150 °C.

[0017] Preferably, the preparation method of the hydrophobically modified nano-titanium dioxide in step (2) is: Disperse nano-titanium dioxide powder in an anhydrous isopropanol solution of a modifier with a mass concentration of 0.1%-2%, and then react with stirring at 50-70 °C for 4-8 h. Subsequently, evaporate the solvent under reduced pressure at 50 °C, and dry at 80-100 °C for 2-6 h. Finally, further grind and screen to prepare surface-hydrophobically modified nano-titanium dioxide;

[0018] The modifier is at least one of perfluorodecyltrimethoxysilane or perfluorononyltrimethoxysilane;

[0019] The mass-volume ratio of the nano-titanium dioxide powder to the anhydrous isopropanol solution of the modifier is 3 g:1 ml-3 g:2 ml;

[0020] The particle size of the hydrophobically modified nano-titanium dioxide is 20-100 nm.

[0021] Preferably, the mass ratio of MPPC-P to the hydrophobically modified nano-titanium dioxide in step (2) is 100:1-10.

[0022] Preferably, the temperature of the feeding section of the melt spinning in step (2) is 35-50°C, the temperature of the melt blending section is 140-170°C, the temperature of the elbow is 150-160°C, and the temperature of the spinning pack is 160-170°C.

[0023] Preferably, the mass ratio of PPC-P to the polymer antibacterial agent in step (3) is 95-100:0-5; the volume ratio of dichloromethane to acetone is 1:1.

[0024] Preferably, the voltage value of the spinning electrode in the electrospinning in step (3) is 25-30 kV, the receiving distance is 10-15 cm, and the average liquid flow rate of each spinneret hole is 0.5-2 ml / h.

[0025] The degradable fiber composite filter material prepared by the above method comprises a three-layer structure, which is successively from bottom to top: the first antibacterial hydrophobic spunbond fiber, the electrospun antibacterial nanofiber, and the second antibacterial hydrophobic spunbond fiber;

[0026] The dosage of the first antibacterial hydrophobic spunbond fiber is 5-30 g / m 2 , the dosage of the electrospun antibacterial nanofiber is 2-15 g / m 2 , and the dosage of the second antibacterial hydrophobic spunbond fiber is 5-30 g / m 2 .

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. In addition to the filtering function, the fibers in the inner and outer surfaces of the degradable fiber composite filter material of the present invention also have a superhydrophobic function, which can prevent external water vapor from entering and being intercepted in the fiber layer, thereby avoiding the defect of the decrease in filtration efficiency caused by the blockage of the filtration pores by water vapor during the use of traditional filter materials;

[0029] 2. The fibers in the middle layer of the degradable fiber composite filter material of the present invention have a nano-scale diameter and a nano-scale pore structure, which can effectively filter particles with a diameter of more than 100 nm (filtration efficiency > 99%), thereby avoiding the defect of insufficient filtration efficiency of traditional filter materials for sub-micron virus and bacterial particles;

[0030] 3. The inner layer, middle layer, and outer layer fibers of the degradable fiber composite filter material of the present invention all contain a polymer antibacterial agent linked by chemical bonds, which can achieve the persistent antibacterial of the three-layer degradable fiber composite filter material, maintain long-term antibacterial, avoid the disinfection process during the production of medical, sanitary, and nursing products, improve the production efficiency of products, reduce the production cost, achieve the persistent antibacterial function, extend the service life of products, reduce the total consumption of products, and achieve the purpose of carbon reduction.

[0031] 4. All raw materials and additives used in the degradable fiber composite filter material of the present invention are completely biodegradable materials, and all materials are derived from carbon dioxide synthetic resin. On the one hand, it is conducive to realizing the recycling of carbon dioxide waste gas resources. On the other hand, after use, it can be completely biodegradable into carbon dioxide and water, thus avoiding the environmental pollution drawbacks caused by the non-biodegradability of traditional fibers such as polypropylene.

[0032] 5. Titanium dioxide with photocatalytic effect is added to the raw materials of the degradable fiber composite filter material of the present invention. The degradation period after use and discard can be adjusted by the addition ratio of titanium dioxide. The degradation period of the degradable fiber composite filter material can be regulated, thus avoiding the drawbacks of the uncontrollable degradation period of conventional degradable resins and the formation of a large number of micron-sized plastic particles after degradation, resulting in secondary environmental pollution. Description of the Drawings

[0033] Figure 1 Schematic diagram of the surface micro-nano concave and convex structure of the antibacterial hydrophobic spunbond fiber of the present invention;

[0034] Figure 2 Antibacterial effect of degradable fibers on different strains for 48h detected by the inhibition zone method;

[0035] Figure 3 Comparison result of the morphology of the material after 10 weeks of degradation with the initial morphology when 6 parts of titanium dioxide are added to PPC-P3;

[0036] Figure 4 Biodegradation rate of PPC-P3 materials with different titanium dioxide addition ratios in the examples and comparative examples of the present invention. Detailed Embodiments

[0037] The present invention provides a preparation method of a degradable fiber composite filter material, and the steps are as follows:

[0038] (1) PPC-P modification: Dry PPC-P, then mix it evenly with a polymer antibacterial agent, and carry out melt blending, extrusion, cooling, and pelletizing to obtain a modified PPC-P spinning raw material (MPPC-P);

[0039] The specific structure of the PPC-P is as shown in formula (1), and the structure of the polymer antibacterial agent is as shown in formula (2):

[0040]

[0041] (2) Manufacture of antibacterial hydrophobic spunbond fiber: After mixing MPPC-P and hydrophobically modified nano-titanium dioxide evenly, carry out melt spinning to obtain antibacterial hydrophobic spunbond fiber;

[0042] (3) Preparation of electrospun antibacterial nanofibers: Mix PPC-P and a polymeric antibacterial agent, and add them to a mixed solvent of dichloromethane and acetone to obtain a spinning solution with a concentration of 5-10 wt%. Then, perform electrospinning using the spinning solution to obtain electrospun antibacterial nanofibers;

[0043] (4) Lay and stack antibacterial hydrophobic spunbond fibers, electrospun antibacterial nanofibers, and antibacterial hydrophobic spunbond fibers from bottom to top, and then perform roll hot pressing to obtain the degradable fiber composite filter material.

[0044] Preferably, the drying temperature in step (1) is 50-70 °C, and the drying time is 5-8 h.

[0045] Preferably, the mass ratio of PPC-P to the polymeric antibacterial agent in step (1) is 100:0.5-10.

[0046] Preferably, the temperature of the feeding section for melt blending in step (1) is 35-50 °C, the temperature of the melt blending section is 150-200 °C, and the temperature of the extrusion die is 150 °C.

[0047] In step (1) of the present invention, the number average molecular weight of PPC-P is 30,000-100,000, and the number average molecular weight distribution of the polymeric antibacterial agent is 1,000-50,000; in this process, the polymeric antibacterial agent and PPC-P are melt blended and modified to carry out a grafting reaction to obtain MPPC-P with a graft product structure. The structure of MPPC-P is as shown in formula (3):

[0048]

[0049] The melt flow rate distribution range of the MPPC-P under the conditions of 170 °C and 2.16 kg is: 10-200 g / 10 min.

[0050] In a specific embodiment of the present invention, the preparation method of the hydrophobic modified nano-titanium dioxide in step (2) is: Disperse nano-titanium dioxide powder in an anhydrous isopropanol solution of perfluorodecyltrimethoxysilane with a mass concentration of 0.5%, and then react with stirring at 60 °C for 4 h. Subsequently, evaporate the solvent under reduced pressure at 50 °C, dry at 100 °C for 2 h, and finally further grind and screen to prepare surface-hydrophobic modified nano-titanium dioxide;

[0051] The mass-volume ratio of the nano-titanium dioxide powder to the anhydrous isopropanol solution of the modifier is 3 g:1.5 ml;

[0052] The particle size of the hydrophobic modified nano-titanium dioxide is 20-100 nm.

[0053] Preferably, the mass ratio of the MPPC-P to the hydrophobically modified nano-titanium dioxide in step (2) is 100:1 to 10.

[0054] Preferably, the temperature of the feeding section of the melt spinning in step (2) is 35 to 50 °C, the temperature of the melt blending section is 140 to 170 °C, the temperature of the elbow is 150 to 160 °C, and the temperature of the spinning pack is 160 to 170 °C.

[0055] The diameter of the antibacterial and hydrophobic spunbond fibers obtained in step (2) of the present invention is distributed in the range of 7 to 25 μm. The surface of the antibacterial and hydrophobic spunbond fibers has a micro-nano concave-convex structure, the height of the protrusions in the concave-convex structure is 7 to 15 μm, and the gap between the protrusions is 5 to 8 μm. Such micron-scale protrusions are formed by the accumulation of multiple titanium dioxide nanoparticles (as Figure 1 shown), and the contact angle between the fiber surface and water can reach more than 120°, thus achieving a high hydrophobic function.

[0056] Preferably, the mass ratio of the PPC-P to the polymer antibacterial agent in step (3) is 95 to 100:0 to 5; the volume ratio of dichloromethane to acetone is 1:1.

[0057] Preferably, the voltage value of the spinning electrode in the electrospinning in step (3) is 25 to 30 kV, the receiving distance is 10 to 15 cm, and the average liquid flow rate of each spinneret hole is 0.5 to 2 ml / h.

[0058] The diameter of the electrospun antibacterial nanofibers obtained in step (3) of the present invention is distributed in the range of 50 to 500 nm, and the fiber pore size > 50 nm, thereby realizing the fine filtration of bacteria and virus particles with particle sizes above 100 nm.

[0059] The degradable fiber composite filter material prepared by the above method comprises a three-layer structure, which is successively from bottom to top the first antibacterial and hydrophobic spunbond fiber (gram weight 5 to 30 g / m 2 ), the electrospun antibacterial nanofiber (gram weight 2 to 15 g / m 2 ), and the second antibacterial and hydrophobic spunbond fiber (gram weight 5 to 30 g / m 2 ) 。

[0060] The inner layer, middle layer and outer layer fibers of the degradable fiber composite filter material prepared by the present invention all contain a polymer antibacterial agent with a persistent and stable structure, which can avoid migration and enrichment, realize the persistent and stable antibacterial of the degradable fiber composite filter material, and no detection is found in the leaching solution after continuous leaching in water for 24 h, and the antibacterial rate of the composite fiber can reach more than 99%. And all raw materials and additives used have complete biodegradability, which can avoid environmental pollution caused by the non-biodegradability of traditional polypropylene and other fibers.

[0061] The present invention will be further described below in conjunction with examples and comparative examples.

[0062] Example 1

[0063] A preparation method of a degradable fiber composite filter material is as follows:

[0064] (1) PPC-P modification: Dry PPC-P at 50 °C for 8 h, then mix 100 parts of the dried PPC-P and 0.5 part of the polymer antibacterial agent evenly. Set the temperature of the first-zone feeding section to 50 °C, and the temperatures of the second to fifth-zone melting and mixing sections to 150 °C, 160 °C, 165 °C, 170 °C, and the temperature of the sixth-zone extrusion die to 150 °C. The screw speed is 150 revolutions per minute. Carry out melt blending, extrusion, cooling, and pelletizing in a screw device to obtain the antibacterial modified material MPPC-P1. Using the same steps, by changing the mass ratio of PPC-P to the polymer antibacterial agent to 100:1, 100:2, 100:3, 100:4 respectively, the antibacterial modified materials MPPC-P2, MPPC-P3, MPPC-P4, MPPC-P5 can be prepared respectively, and the process formulations are shown in Table 1. Through the antibacterial performance evaluation of the spinning modified raw materials MPPC-P1 to MPPC-P5, finally considering comprehensively from the material cost and antibacterial performance (the specific test results are shown in Table 2), MPPC-P3 is selected as the raw material for subsequent antibacterial hydrophobic spunbond fiber spinning.

[0065] (2) Manufacture of antibacterial hydrophobic spunbond fibers: After mixing 100 parts of MPPC-P3 and 2 parts of hydrophobically modified nano-titanium dioxide evenly, set the temperature of the first-zone feeding section to 50 °C, and the temperatures of the second to fourth-zone melting sections to 150 °C, 165 °C, 175 °C, the temperature of the elbow to 160 °C, and the temperature of the spinning component to 170 °C. Carry out melt spinning, stretching, cooling, filament splitting, web forming, strengthening, and winding at a screw speed of 100 revolutions per minute to obtain the antibacterial hydrophobic spunbond fiber MPPC-P3-T1. Using the same steps and spinning process conditions, by changing the mass ratio of MPPC-P3 to hydrophobically modified nano-titanium dioxide to 100:4, 100:6, 100:8, 100:10 respectively, the antibacterial hydrophobic spunbond fibers MPPC-P3-T2, MPPC-P3-T3, MPPC-P3-T4, MPPC-P3-T5 are prepared, and the process formulations are shown in Table 3;

[0066] (3) Fabrication of electrospun antibacterial nanofibers: Mix PPC-P and the polymer antibacterial agent in a mass ratio of 99.50:0.5, then add it to a mixed solvent with a volume ratio of dichloromethane to acetone of 1:1 to obtain a spinning solution with a concentration of 10 wt%. Set the electrospinning electrode voltage value to 30 kV, the receiving distance to 15 cm, and the average liquid flow rate of each spinneret hole to 1 ml / h. Use the spinning solution for electrospinning to obtain electrospun antibacterial nanofibers PPC-P-E1. Using the same steps and electrospinning process conditions, by changing the mass ratios of PPC-P and the polymer antibacterial agent to 99:1, 98:2, 97:3, and 96:4 respectively, antibacterial nanofibers PPC-P-E2, PPC-P-E3, PPC-P-E4, and PPC-P-E5 are prepared, and the process formulations are shown in Table 4;

[0067] (4) Degradable fiber combination composite: Lay and stack antibacterial hydrophobic spunbond fibers, electrospun antibacterial nanofibers, and antibacterial hydrophobic spunbond fibers from bottom to top, then use a roller for hot pressing (100 °C), and finally trim the edges and wind up to obtain the degradable fiber combination composite filter material PPC-P3-T1E1T1.

[0068] The degradable fiber composite filter material comprises a three-layer structure, which is, from bottom to top, a first antibacterial hydrophobic spunbond fiber layer (15 g / m 2 ), an electrospun antibacterial nanofiber layer (8 g / m 2 ), and a second antibacterial hydrophobic spunbond fiber layer (15 g / m 2 ) 。

[0069] In the molecular structure of PPC-P, m / n = 7 / 3, the number-average molecular weight is 53,000, and the polydispersity is 2.5.

[0070] The number-average molecular weight of the polymer antibacterial agent is 25,000;

[0071] Using the same experimental implementation steps as in Example 1, by only changing the raw material addition ratios and electrospinning process parameters in steps (1) to (3) of Example 1, different antibacterial modified PPC-P spunbond spinning raw materials, antibacterial hydrophobic spunbond fibers, and antibacterial nanofiber materials can be prepared respectively, as shown in Table 5.

[0072] Table 1 Antibacterial modified material formula and process conditions

[0073] Serial number PPC-P / part Polymer antibacterial agent / part Processing temperature (°C) Product name P1 100 0.5 150～170 MPPC-P1 P2 100 1 150～170 MPPC-P2 P3 100 2 150～170 MPPC-P3 P4 100 3 150～170 MPPC-P4 P5 100 4 150～170 MPPC-P5

[0074] Table 2 Antibacterial performance evaluation results of MPPC-P antibacterial modified materials

[0075]

[0076] Table 3 Formulation and Process Conditions for Preparing Antibacterial Hydrophobic Spunbond Fibers

[0077] Serial number MPPC-P3 / part Modified nano-titanium dioxide / part Processing temperature (°C) Product name T1 100 2 150～175 MPPC-P3-T1 T2 100 4 150～175 MPPC-P3-T2 T3 100 6 150～175 MPPC-P3-T3 T4 100 8 150～175 MPPC-P3-T4 T5 100 10 150～175 MPPC-P3-T5

[0078] Table 4 Formulation for Preparing Antibacterial Nanofibers

[0079]

[0080] The sample MPPC-P3-T1 of the antibacterial hydrophobic spunbond fiber prepared in step (2) was used as the top and bottom composite materials of the fiber-reinforced material, and the sample PPC-P-E1 of the electrospun antibacterial nanofiber prepared in step (3) was used as the middle-layer composite material of the fiber-reinforced material. Then, through hot pressing, trimming, and winding, the degradable fiber composite filter material sample MPPC-P3-T1E1T1 was obtained.

[0081] Examples 2 - 5

[0082] Using different antibacterial hydrophobic spunbond fibers and electrospun antibacterial nanofibers as raw materials, the antibacterial hydrophobic spunbond fiber layer and the electrospun antibacterial nanofiber layer were combined and compounded according to the same combination compounding process and method as in step (4) of Example 1, and the degradable fiber composite filter material samples could be prepared. The specific components and products are shown in Table 5.

[0083] Table 5 Degradable Fiber Composite Combination Modes in Each Example

[0084] Serial number Top layer Middle layer Bottom layer Hot pressing temperature Sample name Example 1 MPPC-P3-T1 PPC-P-E1 ​ 100℃ ​ ​ ​ ​ ​ 100℃ ​ ​ ​ ​ ​ 100℃ ​ ​ ​ ​ ​ 100℃ ​ ​ ​ ​ ​ 100℃ ​

[0085] Comparative Example 1

[0086] Using pure PPC-P resin as the raw material (no antibacterial agent was added to each layer of fibers in this comparative example), according to the same steps and process conditions in each stage of Example 1, the spunbond fiber PPC-P-T (10 g / m 2 ) and the nanofiber PPC-P-E (5 g / m 2 ) were respectively prepared. Then, using the same steps, the three kinds of fibers were hot-pressed and compounded to prepare the pure PPC-P composite fiber filter material sample, recorded as PPC-P-TET.

[0087] Comparative Example 2

[0088] A commercially available ordinary polypropylene SMS non-woven fabric from Shandong Huaye Non-woven Fabric Company (product name: SMMS non-woven fabric, specification: gram weight 50 g / square meter, width 1000 mm) was used as the comparative test sample.

[0089] Comparative Example 3

[0090] Use the polylactic acid mask non-woven fabric (product name: melt-blown non-woven fabric, specification: gram weight 45 gsm, width 30 cm) commercially available from Easpring New Materials (Suzhou) Co., Ltd. as the comparative test sample.

[0091] Comparative Example 4

[0092] Use the polypropylene antibacterial SMS non-woven fabric for medical protective products (product name: medical non-woven fabric (SMS), specification: gram weight 50 gsm, width 50 cm) produced by Zhejiang Huachen Non-woven Fabric Co., Ltd. as the comparative test sample.

[0093] For the performance tests of different materials prepared in Example 1 and Comparative Examples 1-4, the performance test results of different products in Examples 1-5 and Comparative Examples 1-4 are shown in Table 6, and the performance test methods for each product are as follows:

[0094] Gram weight measurement: The gram weight measurement of fiber materials refers to "GB / T 24218.1-2009 Textiles - Test methods for non-woven fabrics - Part 1: Determination of mass per unit area";

[0095] Filtration efficiency: Detection is carried out with reference to 5.5 in "GB 19083—2023 Medical protective masks";

[0096] Air permeability: Refer to "GB / T 24218.15-2018 Textiles - Test methods for non-woven fabrics - Part 15: Determination of air permeability";

[0097] Resistance to synthetic blood penetration: Detection is carried out with reference to the method specified in YY / T 0691—2008;

[0098] Antibacterial performance: Refer to "GB / T 20944.1-2007 Textiles - Evaluation of antibacterial properties - Part 1: Agar plate diffusion method" (i.e., the inhibition zone method, and the effect is relatively intuitive to observe by the diffusion method) and "GB / T 20944.3-2008 Textiles - Evaluation of antibacterial properties - Part 3: Oscillation method" (the oscillation method is convenient for quantifying the antibacterial efficiency).

[0099] Contact angle: Refer to "GB / T 42694-2023 Textiles - Detection and evaluation of surface anti-wetting properties - Contact angle and rolling angle method".

[0100] Dissolution property: Cut the fiber membrane sample into a 3 cm × 3 cm sample with a cutter as the test sample, and have 3 parallel samples for each. Before the test starts, first weigh the weight of the dried and constant-weight test sample with an electronic analytical balance and record it as L0. Then, clamp the dried test sample with clean stainless steel forceps and immerse it in a room-temperature alcohol-water mixed solvent at about 25 °C (add 6 volumes of deionized water to 4 volumes of absolute ethanol). During the immersion process, ensure that the sample is always below the liquid level. When the sample has been immersed at room temperature for 72 h, terminate the immersion. After the immersion is completed, take out the sample from the solvent with stainless steel forceps. After the solvent on the sample surface has dripped clean, then place the sample in an oven at 100 °C and dry it to a constant weight. Then, weigh its weight after immersion and drying with an electronic analytical balance and record it as L1. The calculation formula for the dissolution rate of the sample is as shown in Equation (4):

[0101] Water dissolution rate (%) = (L0 - L1) / L0 × 100% (4)

[0102] Degradation performance: Refer to "GB / T19811-2005 Determination of the degree of disintegration of plastic materials under defined composting pilot conditions" and "GB / T19277.1-2011 Determination of the ultimate aerobic biodegradability of materials under controlled composting conditions - Method by measuring the evolved carbon dioxide - Part 1: General method" for testing (experimental soil conditions: 58 °C, 50% humidity).

[0103] Table 6 Comparison of the main properties of the products of each example

[0104]

[0105] In the table, a. The evaluation strain for this antibacterial rate is Staphylococcus aureus.

[0106] From the comparison of the performance of the products in each example and the comparative examples in Table 6, it can be seen that the three-layer combined composite fiber filter material prepared by the present invention has a lower thickness, is thinner and lighter, has better air permeability, higher antibacterial efficiency, and no detectable dissolution products compared with the current commercially available similar products, and has a higher filtration efficiency. Except for the polylactic acid product, the others are made of polypropylene and have extremely low degradation performance, while the PPC-P used in the present invention can be completely biodegradable.

[0107] The antibacterial effect of the degradable fiber on different strains for 48 h was detected by the inhibition zone method, and the results are as ​ , ​ In the upper two figures, it is Staphylococcus aureus, in the middle two figures, it is Escherichia coli, and in the lower two figures, it is Candida albicans. In the figures, the fiber sample 1 corresponds to the sample of Example 2, the fiber sample 2 corresponds to the sample of Example 3, the fiber sample 3 corresponds to the sample of Example 4, and the fiber sample 4 corresponds to the sample of Example 5.

[0108] ​ The comparison result of the material after 10 weeks of degradation with the initial morphology when 6 parts of titanium dioxide are added to PPC-P3.

[0109] From ​ it can be seen that the product developed by the technology of the present invention has broad-spectrum antibacterial properties in terms of antibacterial performance. At the same time, due to the use of polymer antibacterial agents that can be chemically coupled and bonded to PPC-P, they will not migrate and accumulate. Currently, small molecule or metal antibacterial agents are used in the industry. Although the antibacterial efficiency is also very high, there are drawbacks of migration. Especially heavy metals have potential risks of enrichment toxicity. Ordinary SMS materials hardly have antibacterial properties and are prone to bacterial growth during use.

[0110] ​ The comparison of the biodegradation rates of the spunbond fiber materials PPC-P3-T to PPC-P3-T5 after different proportions of nano-titanium dioxide are added to the MPPC-P3 material in the examples and comparative examples of the present invention (degradation time: 10 weeks).

[0111] In addition, both the inner and outer layers of the composite filter material prepared by the present invention have high hydrophobicity, which can avoid the blockage of filter pores by water vapor compared with traditional SMS non-woven fabrics. If used in medical and health products, the wearing comfort experience will be better than that of traditional polypropylene SMS non-woven fabrics. Moreover, due to the addition of nano-titanium dioxide in the technical product of the present invention, it also has a catalytic disintegration effect during the material degradation process. Compared with the material without the addition of titanium dioxide, its degradation rate increases with the increase of the addition amount under the same conditions. Therefore, the degradation period of the degradable material prepared by the technology of the present invention can be adjusted according to needs by adjusting the content ratio of titanium dioxide, so as to control its degradation period in the natural environment.

[0112] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a degradable fiber composite filter material, characterized in that, It includes the following steps: (1) PPC-P modification: Dry PPC-P, then mix it evenly with a polymer antibacterial agent, and conduct melt blending, extrusion, cooling, and pelletizing to obtain MPPC-P; The specific structure of the PPC-P is as shown in formula (1), and the structure of the polymer antibacterial agent is as shown in formula (2): (2) Manufacture of antibacterial hydrophobic spunbond fibers: After mixing MPPC-P and hydrophobically modified nano-titanium dioxide evenly, conduct melt spinning to obtain antibacterial hydrophobic spunbond fibers; (3) Manufacture of electrospun antibacterial nanofibers: Mix PPC-P and a polymer antibacterial agent, add them to a mixed solvent of dichloromethane and acetone to obtain a spinning solution with a concentration of 5-10 wt%, and then conduct electrospinning using the spinning solution to obtain electrospun antibacterial nanofibers; (4) Lay and stack the antibacterial hydrophobic spunbond fibers, electrospun antibacterial nanofibers, and antibacterial hydrophobic spunbond fibers from bottom to top, and then use a roller for hot pressing to obtain the degradable fiber composite filter material.

2. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that, The temperature of the drying in step (1) is 50-70°C, and the drying time is 5-8 h.

3. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that, The mass ratio of the PPC-P to the polymer antibacterial agent in step (1) is 100:0.5-10.

4. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that The temperature of the feeding section for the melt blending in step (1) is 35-50°C, the temperature of the melt blending section is 150-200°C, and the temperature of the extrusion die is 150°C.

5. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that, The preparation method of the hydrophobically modified nano-titanium dioxide in step (2) is: Disperse nano-titanium dioxide powder in an anhydrous isopropanol solution of a modifier with a mass concentration of 0.1%-2%, and then react with stirring at 50-70°C for 4-8 h. Subsequently, evaporate the solvent under reduced pressure at 50°C, and dry at 80-100°C for 2-6 h. Finally, conduct further grinding and screening to prepare surface-hydrophobically modified nano-titanium dioxide; The modifier is at least one of perfluorodecyltrimethoxysilane or perfluorononyltrimethoxysilane; The mass-volume ratio of the nano-titanium dioxide powder to the anhydrous isopropanol solution of the modifier is 3 g:1 ml-3 g:2 ml; The particle size of the hydrophobically modified nano-titanium dioxide is 20-100 nm.

6. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that, The mass ratio of the MPPC-P to the hydrophobically modified nano-titanium dioxide in step (2) is 100:1-10.

7. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that, The temperature of the feeding section for the melt spinning in step (2) is 35-50°C, the temperature of the melt blending section is 140-170°C, the temperature of the elbow is 150-160°C, and the temperature of the spinning pack is 160-170°C.

8. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that, The mass ratio of the PPC-P to the polymer antibacterial agent in step (3) is 95-100:0-5; the volume ratio of the dichloromethane to the acetone is 1:

1.

9. The preparation method of the degradable fiber composite filter material according to claim 1, characterized in that The voltage value of the spinning electrode for the electrospinning in step (3) is 25-30 kV, the receiving distance is 10-15 cm, and the average liquid flow rate of each spinneret hole is 0.5-2 ml / h.

10. A degradable fiber composite filter material prepared by any one of the methods of claims 1 to 9, characterized in that, The degradable fiber composite filter material includes a three-layer structure, which is, from bottom to top, the first antibacterial hydrophobic spunbond fiber, electrospun antibacterial nanofiber, and the second antibacterial hydrophobic spunbond fiber; The dosage of the first antibacterial hydrophobic spunbond fiber is 5 - 30 g / m 2 , the dosage of the electrospun antibacterial nanofiber is 2 - 15 g / m 2 , the dosage of the second antibacterial hydrophobic spunbond fiber is 5 - 30 g / m 2 .

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