A process for preparing a bacterial grass fiber and a process for preparing an antibacterial product

Abstract

The application discloses a preparation process of a fungus grass fiber and a preparation process of an antibacterial product, and belongs to the technical field of health products. ‑ Static complex is formed, and the double-network antibacterial body of ganoderma polysaccharide-epsilon-polylysine significantly improves antibacterial durability; the middle layer adopts PLA / acetyl citric acid tributyl ester plasticizing master batch, so that the glass transition temperature of PLA is reduced to 42 DEG C, the surface is slightly melted at 120 DEG C on-line hot pressing, nanoscale melting anchoring is formed, interlayer self-adhesion is realized, and the balance between filtering efficiency and breathing resistance is optimized; the outer layer adopts fluorine-free plasma grafted C6-alkyl chain, the static contact angle is greater than or equal to 130 DEG, liquid repellency effect is achieved, and the environmental persistence problem caused by traditional fluorocarbon water repellent agent is avoided; the three-layer coaxial one-step forming process saves the adhesive, additional hot pressing and hydrophobic finishing steps required in traditional multilayer compounding.

Description

TECHNICAL FIELD

[0001] The application discloses a sanitary product technology, and particularly relates to a preparation process of a bacterial grass fiber and a preparation process of an antibacterial product. BACKGROUND

[0002] The bacterial grass fiber is a regenerated cellulose fiber prepared from bacterial grass as raw material. The bacterial grass fiber is a green and environment-friendly bio-based new material which is prepared by replacing wood with grass to reduce the dependence on traditional wood resources. The bacterial grass fiber has the following characteristics and advantages: natural antibacterial, antibacterial rate of Staphylococcus aureus and Escherichia coli is more than 99%, environment-friendly and degradable, product is naturally degradable, excellent performance, good strength, tensile property and spinnability, and is suitable for high-end clothing, home textiles, medical supplies and other fields.

[0003] The existing bacterial grass fiber still adopts an old route of 'alkali boiling-bleaching-dissolution-spinning', and the consumption of acid and alkali is large, and COD is more than 15000 mg / L; Ag + or quaternary ammonium salt is usually used for post-finishing of antibacterial, and the antibacterial retention rate is low. Therefore, a new preparation process of bacterial grass fiber and antibacterial product is needed. SUMMARY

[0004] The application aims to provide a preparation process of bacterial grass fiber and a preparation process of antibacterial product.

[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme: a preparation process of bacterial grass fiber, comprising the following steps:

[0006] A1, low-acid steam flash explosion, cutting giant bacterial grass, water content is 50%, placing in a 5m 3 flash explosion tank, introducing 0.12 MPa saturated steam for 3 min, and then instantaneously releasing pressure, one step removes hemicellulose and lignin to obtain pulp, the ratio of sulfuric acid consumption mass to absolute dry cellulose mass is 0.13:1, and the pH of waste water is 3.5;

[0007] A2, enzymatic degrading viscosity, adjusting the pulp in step A1 to pH 4.8, adding 0.8 IU / g cellulase Cellic-CTec2, and reacting for 2 h under stirring at 50 DEG C and 120 rpm, and the obtained pulp has a falling ball viscosity of less than 30 mPa·s measured by using a Φ5 mm steel ball;

[0008] A3, covalent anchoring ganoderma fungus bran polysaccharide: adding ganoderma fungus bran polysaccharide to the pulp after enzymatic degradation, the amount of ganoderma fungus bran polysaccharide is 8% of the absolute dry mass of cellulose, the polysaccharide has a molecular weight of 5-30 kDa and a β-glucan content of more than 70%, 3 wt% citric acid is used as a main crosslinking agent, and 0.3 wt% sodium hypophosphite is used as a catalyst, and esterification is carried out at 85 DEG C for 30 min to obtain ganoderma polysaccharide-esterified nanocellulose spinning solution, and the esterification degree is more than 0.35.

[0009] A4, antibacterial reinforcement, add 0.4wt% of ε-polylysine with a molecular weight of 3-5kDa to the ganoderma polysaccharide-esterified nanocellulose spinning solution, complex at 50°C for 30min, form a double network antibacterial body of ganoderma polysaccharide-ε-polylysine, obtain ganoderma polysaccharide-esterified nanocellulose spinning solution;

[0010] A5, 3D acoustic flow spinning, inject 1.5wt% of the obtained ganoderma polysaccharide-esterified nanocellulose spinning solution in step A4 into a 20kHz ultrasonic microreactor, adopt a ring nozzle with a size of 0.15mm×128holes, ultrasonic power 200W, standing wave acoustic pressure 0.42MPa, temperature 40°C, air flow stretching 1.8times, wind speed 15m / s, collection speed 2.2m / min, and obtain 1.33dtex of ganoderma polysaccharide-esterified nanocellulose fiber.

[0011] As preferred, the wastewater in step A1 is directly recycled for the next batch of flash explosion.

[0012] As preferred, the unreacted ganoderma polysaccharide in step A3 is recovered by water washing and recycled.

[0013] A preparation process of an antibacterial product, raw materials prepared by the above preparation process, and the antibacterial product comprising a three-layer structure: an inner hydrophilic antibacterial layer, a middle microporous filtration layer, and an outer hydrophobic liquid blocking layer.

[0014] The three-layer structure adopts a three-layer coaxial one-step forming process in the same ultrasonic microreactor, and comprises the following steps:

[0015] K1, inner layer suspension, adopt the ganoderma polysaccharide-esterified nanocellulose spinning solution in A4 as the inner layer spinning solution A;

[0016] K2, middle layer suspension preparation:

[0017] According to mass fraction, disperse 25parts of the ganoderma polysaccharide-esterified nanocellulose fiber prepared in A5, 55parts of polylactic acid short fiber, and 20parts of PLA / acetyl citric acid tributyl ester plasticizing master batch in deionized water, add 0.1part of SDS, stir at 40°C for 30min by a stirrer, and prepare a middle layer spinning solution B with a solid content of 2.2wt%;

[0018] K3, outer layer suspension preparation:

[0019] According to mass fraction, disperse 70parts of PLA and 30parts of the ganoderma polysaccharide-esterified nanocellulose fiber prepared in A5 in dry state in deionized water, add 0.08parts of Span-80, and prepare an outer layer spinning solution C with a solid content of 2.0wt%;

[0020] K4, three-channel coaxial nozzle setting:

[0021] An inner layer-middle layer-outer layer three-layer annular nozzle is adopted, the outlet diameters are 0.15mm, 0.25mm and 0.35mm respectively, the positioning accuracy is ±5μm, and each layer corresponds to the supply of spinning solution A, B and C;

[0022] K5, ultrasonic standing wave fibrillation and airflow stretching:

[0023] Under the conditions of 20kHz, standing wave acoustic pressure 0.42MPa, ultrasonic power density 80Wcm -2 , temperature 40℃, the spinning solutions A, B and C are simultaneously transported to the nozzle, and the annular airflow with a speed of 15m / s and a temperature of 25℃ is introduced at the nozzle outlet, so that the three-layer fiber is synchronously fibrillated and airflow stretched by 2 times;

[0024] K6, direct webbing without coagulation bath:

[0025] The three-layer fiber after stretching is deposited on a PET spun-bond web curtain with a speed of 0.8m / min, vacuum suction-4kPa, to form a three-layer embryo web with a total grammage of 30-50gm -2 ;

[0026] K7, online interlayer self-bonding:

[0027] The embryo web passes through a hot roller at 120℃ immediately, the linear pressure is 30N / cm, and the residence time is 3s, so that the middle layer and the outer layer PLA surface layer are slightly melted and ester exchange points are generated, the interlayer peeling strength is ≥0.15N / cm, and the porosity is kept ≥75%;

[0028] K8, online hydrophobization without fluorine:

[0029] Immediately after the hot roller, the outer surface of the product is subjected to fluorine-free hydrophobic treatment by normal pressure DBD plasma: n-hexylamine is used as a monomer, N2 is used as a carrier gas, and the power density is 50W / min·m, so that the static contact angle of the outer layer is ≥130°, and the three-layer coaxial one-step forming antibacterial product is completed.

[0030] Compared with the prior art, the beneficial effects of the present application are:

[0031] In the present application, ε-polylysine is added to the inner layer, and electrostatic complexation is formed between the ε-polylysine and the -COO - on the surface of ganoderma polysaccharide-esterified nanocellulose, and the double-network antibacterial body of ganoderma polysaccharide-ε-polylysine significantly improves the antibacterial durability;

[0032] The middle layer adopts PLA / acetyl citric acid tributyl ester plasticizing master batch, so that the glass transition temperature of PLA is reduced to 42℃, the surface is slightly melted during online hot pressing at 120℃, nanoscale melting anchoring is formed, interlayer self-bonding is realized, and the balance between filtration efficiency and respiratory resistance is optimized;

[0033] The outer layer is grafted with C6-alkyl chain by fluorine-free plasma, and the static contact angle is greater than or equal to 130°, so that the liquid repellency effect is achieved, and the environmental persistence problem caused by traditional fluorocarbon water repellent is avoided.

[0034] The three-layer coaxial one-step forming process saves the adhesive, additional hot pressing and hydrophobic finishing steps required in traditional multi-layer compounding. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Sample experimental data chart for filter cloth prepared as a mask for an antibacterial product;

[0036] Figure 2 SEM image before cellulase hydrolysis;

[0037] Figure 3 SEM image after cellulase hydrolysis. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0039] A process for preparing a bacterial grass fiber, comprising the following steps:

[0040] A1, low-acid steam flash explosion, cutting giant bacterial grass, water content 50%, placed in 5m 3 Flash explosion tank, saturated steam 0.12MPa, heat preservation for 3min, instant pressure relief, one step to remove hemicellulose and lignin to obtain pulp, the ratio of sulfuric acid consumption mass to absolute dry cellulose mass is 0.13:1, and the wastewater pH is 3.5;

[0041] The wastewater in step A1 is directly recycled for the next batch of flash explosion;

[0042] As shown in Figure 2 The cellulose obtained by this method has irregular fine cracks, is loose, has a large number of micropores on the surface, but the overall fiber arrangement is still regular and compact, and the cracks mostly occur at the fiber edges and are relatively shallow.

[0043] A2, enzymatic hydrolysis to reduce viscosity: the slurry from step A1 was adjusted to pH 4.8, 0.8 IU / g cellulase Cellic-CTec2 was added, and the mixture was reacted at 50℃ and stirred at 120 rpm for 2 hours. The resulting slurry had a drop ball viscosity of <30 mPa·s when measured with a Φ5 mm steel ball.

[0044] like Figure 3 As shown, after enzymatic hydrolysis to reduce viscosity, the residue is arranged in a disorderly manner, with a large number of very obvious cracks. Most of the cracks penetrate the entire residue and extend deep into the interior of the residue, indicating that the overall structure of cellulose is severely damaged, which means that the enzyme catalytic reaction is complete.

[0045] A3, Covalently Anchored Ganoderma lucidum Mycelium Polysaccharide: Ganoderma lucidum mycelium polysaccharide was added to the enzymatically hydrolyzed slurry. The Ganoderma lucidum mycelium polysaccharide was obtained by hot water extraction and alcohol precipitation. The amount of Ganoderma lucidum mycelium polysaccharide was 8% of the oven-dry weight of cellulose, and the molecular weight of the polysaccharide was 5-30 kDa and the β-glucan content was ≥70%. Using 3wt% citric acid as the main crosslinking agent and 0.3wt% sodium hypophosphite as the catalyst, esterification was carried out at 85℃ for 30 min to obtain Ganoderma lucidum polysaccharide-esterified nanocellulose spinning solution with a degree of esterification ≥0.35.

[0046] The unreacted Ganoderma lucidum mycelium polysaccharide from step A3 is recovered and recycled by washing with water;

[0047] A4, Antibacterial Enhancement: 0.4wt% of ε-polylysine with a molecular weight of 3–5kDa was added to the Ganoderma lucidum polysaccharide-esterified nanocellulose spinning solution and complexed at 50℃ for 30min to form a double network antibacterial body of Ganoderma lucidum polysaccharide-ε-polylysine, thus obtaining the Ganoderma lucidum fiber spinning solution.

[0048] Utilizing two existing reversible non-covalent interactions between Ganoderma lucidum polysaccharide-esterified nanocellulose spinning solution and ε-polylysine, one being electrostatic-ionic bonding, and the other being the residual citrate carboxyl groups (-COO) on the surface of Ganoderma lucidum polysaccharide-esterified nanocellulose. - The degree of esterification was 0.35, and the remaining free COOH was 1.2 mmol / g, while ε-polylysine had a side chain ε-NH3 at pH 4.5-5.0. + Protonation, -NH2+H + →-NH3 + The two pairs of positive and negative charges in a 1:1 ratio to form -COO - The +H3N- salt bridge becomes the main cross-linking point of the network. The carbonyl oxygen of ε-polylysine forms OH…O=C hydrogen bonds with the hydroxyl and unesterified carboxyl groups of Ganoderma lucidum polysaccharide-esterified nanocellulose. At the same time, the MW of the short chain of ε-polylysine is 3-5kDa, which can be inserted into the surface of Ganoderma lucidum polysaccharide-cellulose microcrystals to produce microcrystal block physical entanglement, which enhances the antibacterial retention and stability.

[0049] A5, 3D acoustic flow spinning, 1.5wt% suspension of the Ganoderma lucidum polysaccharide-esterified nanocellulose spinning solution obtained in step A4 is injected into a 20kHz ultrasonic microreactor, a ring nozzle with a size of 0.15mmx128 holes is used, the ultrasonic power is 200W, the standing wave acoustic pressure is 0.42MPa, the temperature is 40℃, the airflow stretching is 1.8 times, the wind speed is 15m / s, and the collection speed is 2.2m / min, to obtain 1.33dtex fungus grass fibers;

[0050] A preparation process of an antibacterial product, raw materials prepared by the above preparation process, and the antibacterial product comprising a three-layer structure: an inner hydrophilic antibacterial layer, a middle microporous filtration layer, and an outer hydrophobic liquid blocking layer;

[0051] The three-layer structure is formed by a three-layer coaxial one-step forming process in the same ultrasonic microreactor, comprising the following steps:

[0052] K1, inner layer suspension, using the fungus grass fiber spinning solution in A4 as the inner layer spinning solution A;

[0053] K2, middle layer suspension preparation:

[0054] According to mass fraction, 25 parts of fungus grass fibers prepared in A5, 55 parts of polylactic acid short fibers, and 20 parts of PLA / acetyl citric acid tributyl ester plasticizing master batch are dispersed in deionized water, 0.1 parts of SDS are added, and the mixture is stirred at 40℃ for 30min by a stirrer to prepare a middle layer spinning solution B with a solid content of 2.2wt%;

[0055] K3, outer layer suspension preparation:

[0056] According to mass fraction, 70 parts of PLA and 30 parts of fungus grass fibers prepared in A5 are dry blended and then dispersed in deionized water, 0.08 parts of Span-80 is added, and a solid content of 2.0wt% of the outer layer spinning solution C is prepared;

[0057] K4, three-channel coaxial nozzle setting:

[0058] An inner layer-middle layer-outer layer three-layer ring nozzle is used, the outlet diameters are 0.15mm, 0.25mm, and 0.35mm respectively, the positioning accuracy is ±5μm, and the spinning solutions A, B, and C are supplied correspondingly;

[0059] K5, ultrasonic standing wave fibrillation and airflow stretching:

[0060] In a 20kHz ultrasonic microreactor, the standing wave acoustic pressure is 0.42MPa, the ultrasonic power density is 80Wcm -2Simultaneously, the spinning solutions A, B, and C are delivered to the nozzles under the condition of a temperature of 40°C, and an annular airflow with a speed of 15 m / s and a temperature of 25°C is introduced at the outlet of the nozzles, the flow rates being A: 0.8 mL / min, B: 1.2 mL / min, and C: 0.9 mL / min, so that the three layers of fibers are simultaneously fibrillated and air-jet stretched by 2 times;

[0061] K6, Directly webbing without coagulation bath:

[0062] The stretched three-layer fibers are deposited on a PET spunbond web curtain with a speed of 0.8 m / min, vacuum suction of -4 kPa, to form a three-layer embryo web with a total basis weight of 30-50 g / m -2 ;

[0063] K7, In-line interlayer self-bonding:

[0064] The embryo web then passes through a hot roller at 120°C, with a line pressure of 30 N / cm and a residence time of 3 s, so that the middle layer and the outer PLA surface layer are slightly melted and ester exchange points are generated, achieving an interlayer peeling strength of ≥0.15 N / cm, while the porosity is maintained at ≥75%;

[0065] The Tg of the middle layer PLA / acetyl citrate tributyl ester has been reduced to 42°C, and under the hot roller at 120°C, the surface segment moves, and ester exchange occurs with the outer PLA and the ganoderma polysaccharide-citrate ester groups on the surface of the inner straw fiber, forming nanoscale melting anchors under the catalysis of 20 ppm Sn(Oct)2, increasing the peeling strength, while the porosity is still maintained at ≥75%.

[0066] K8, Fluorine-free online hydrophobization:

[0067] Immediately after the hot roller, the outer surface of the product is subjected to fluorine-free hydrophobic treatment by normal-pressure DBD plasma: n-hexylamine is used as a monomer, N2 is used as a carrier gas, C6-alkyl chains are grafted, liquid repellency is achieved, and the environmental persistence problem caused by traditional fluorocarbon repellents is avoided, the power density is 50 W / min·m, the outer layer static contact angle is ≥130°, and the three-layer coaxial one-step forming antibacterial product is completed;

[0068] As shown in the chart in Figure 1 , the antibacterial product is prepared as a filter cloth for a mask for sample experiments, in Comparative Example 1, no plasticizer masterbatch is added to the PLA middle layer suspension B, the PLA is not plasticized, the hot roller cannot produce surface melting, the peeling strength decreases by 61%, the air resistance increases by 82%, and the BFE decreases by 2.2%, indicating that the semi-melt interface brought by acetyl citrate tributyl ester is the core of low resistance and high filtration;

[0069] In Comparative Example 2, the outer layer is replaced with a traditional fluorocarbon repellent, and the degradation rate directly decreases to 0, the fluorine content exceeds 10 times the standard, and it cannot pass the biodegradable detection certification OK-Compost, verifying that the fluorine-free plasma process is a necessary means to maintain full biodegradability.

[0070] In Comparative Example 3, ε-polylysine was delayed to the spinning stage, i.e. side- line injection of 0.4wt% solution of cellulose dry weight into the middle layer suspension B in a static mixer before the entrance of the three-channel coaxial nozzle, and then into the 40℃ ultrasonic microreactor for spinning: due to the local concentration of ε-polylysine being too high at the nozzle caused by ultrasonic cavitation, the cationic aggregation of ε-polylysine at the nozzle caused reversible hole blocking, the antibacterial durability decreased by 5.5%, and 2% of raw materials were consumed, proving that complexation in the raw material stage has performance and cost advantages.

[0071] Example 1 simultaneously satisfies: BFE≥99%, ΔP≤29.4Pa, antibacterial rate≥97% after 50 times of severe disinfection, 90d degradation≥99%, and no fluorine and heavy metals are detected.

[0072] It is apparent for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0073] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A process for the preparation of bacterial grass fiber, characterized in that, Comprising the following steps: A1, low acid steam flash explosion, cut segment of giant reed, moisture content of 50%, placed in 5m 3 Flash explosion tank, saturated steam of 0.12 MPa was introduced for 3 min and then instantaneously released, which removed hemicellulose and lignin in one step to obtain pulp, the ratio of sulfuric acid consumption mass to absolute dry cellulose mass was 0.13:1, and the wastewater pH was 3.5; A2, enzymatic viscosity reduction, the slurry in step A1 is adjusted to pH 4.8, 0.8 IU / g of cellulase Cellic-CTec2 is added, and the reaction is carried out at 50°C with stirring at 120 rpm for 2h, and the obtained slurry has a falling ball viscosity of <30 mPa·s measured using a Φ5mm steel ball; A3, covalent anchoring of ganoderma straw polysaccharide: ganoderma straw polysaccharide is added to the enzymatically treated slurry, the amount of ganoderma straw polysaccharide is 8% of the dry mass of cellulose, and the polysaccharide has a molecular weight of 5-30 kDa and a β-glucan content of ≥70%, 3wt% citric acid is used as the main crosslinking agent and 0.3wt% sodium hypophosphite is used as the catalyst, and esterification is carried out at 85°C for 30min to obtain ganoderma polysaccharide-esterified nanocellulose spinning solution with an esterification degree of ≥0.35; A4, antibacterial strengthening, 0.4wt% of ε-polylysine with a molecular weight of 3-5kDa is added to the ganoderma polysaccharide-esterified nanocellulose spinning solution, and complexation is carried out at 50°C for 30min to form a double-network antibacterial body of ganoderma polysaccharide-ε-polylysine, and a straw fiber spinning solution is obtained; A5, 3D acoustic flow spinning, 1.5wt% of the suspension of the straw fiber spinning solution obtained in step A4 is injected into a 20kHz ultrasonic microreactor, a ring nozzle with a size of 0.15mm×128 holes is used, the ultrasonic power is 200W, the standing wave acoustic pressure is 0.42MPa, the temperature is 40°C, the air flow stretching is 1.8 times, the wind speed is 15m / s, and the collection speed is 2.2m / min, and a straw fiber with a fineness of 1.33dtex is prepared.

2. The process for preparing grass fiber according to claim 1, wherein, The wastewater in step A1 is directly recycled for the next batch of flash explosion.

3. The process for preparing grass fiber according to claim 1, wherein, The unreacted ganoderma straw polysaccharide in step A3 is washed with water and recycled.

4. A bacterial grass fiber, characterized by, The straw fiber is prepared by the process according to any one of claims 1-3.

5. A process for the preparation of an antimicrobial article, characterized in that, The straw fiber according to claim 4 is used as the raw material, and the antibacterial product comprises a three-layer structure: an inner hydrophilic antibacterial layer, a middle microporous filtration layer, and an outer hydrophobic liquid blocking layer. The three-layer structure is formed by a three-layer coaxial one-step forming process in the same ultrasonic microreactor, comprising the following steps: K1, inner layer suspension, the straw fiber spinning solution in A4 is used as the inner layer spinning solution A; K2, middle layer suspension preparation: According to mass fraction, 25 parts of the straw fiber prepared in claim 4, 55 parts of polylactic acid short fiber, and 20 parts of PLA / acetyl tri-n-butyl citrate plasticizer master batch are dispersed in deionized water, 0.1 part of SDS is added, and stirring is carried out at 40°C for 30min by a stirrer to prepare a middle layer spinning solution B with a solid content of 2.2wt%; K3, outer layer suspension preparation: According to mass fraction, 70 parts of PLA and 30 parts of the straw fiber prepared in A5 are dry blended and dispersed in deionized water, 0.08 parts of Span-80 is added, and an outer layer spinning solution C with a solid content of 2.0wt% is prepared; K4, three-channel coaxial nozzle setting: An inner layer-middle layer-outer layer ring nozzle is used, the outlet diameters are 0.15mm, 0.25mm, and 0.35mm respectively, the positioning accuracy is ±5μm, and the corresponding spinning solutions A, B, and C are supplied; K5, ultrasonic standing wave fibrillation and air flow stretching: Under the conditions of 20 kHz, standing wave acoustic pressure 0.42 MPa, ultrasonic power density 80 W·cm -2 Simultaneously, the spinning solutions A, B and C were transported to the nozzles under the conditions of 20 kHz, standing wave acoustic pressure 0.42 MPa, ultrasonic power density 80 W·cm -2 , temperature 40℃, and an annular airflow with a speed of 15 m / s and a temperature of 25℃ was introduced at the outlet of the nozzles to make the three layers of fibers synchronously fibrillate and be air-laid by 2 times. K6, direct webbing without coagulation bath: The stretched three-layer fibres were deposited on a PET spunbond curtain at a speed of 0.8 m / min, vacuum suction - 4 kPa, forming a three-layer embryo web with a total basis weight of 30-50 g / m2. -2 The stretched three-layer fibres were deposited on a PET spunbond curtain at a speed of 0.8 m / min, vacuum suction - 4 kPa, forming a three-layer embryo web with a total basis weight of 30-50 g / m2. K7, online interlayer self-adhesion: The embryo net then passes through a 120℃ hot roller with a linear pressure of 30 N / cm and a residence time of 3 s, which causes the middle layer and the outer layer of PLA surface layer to be slightly melted and produce ester exchange points, achieving an interlayer peeling strength of ≥0.15 N / cm while maintaining a porosity of ≥75%; K8, online fluorine-free hydrophobization: Immediately after the hot roller, the outer surface of the product is subjected to fluorine-free hydrophobic treatment with normal pressure DBD plasma: n-hexylamine as monomer, N2 as carrier gas, power density 50 W / min·m, so that the outer layer static contact angle is ≥130°, completing the one-step molding of the three-layer coaxial antibacterial product.

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