Preparation method of moisture-resistant and swelling-resistant degradable mask material

Abstract

The application relates to a preparation method of a moisture-resistant and swelling-resistant degradable mask material, and belongs to the technical field of textile materials, which comprises a preparation method A of a mask air filter membrane and a preparation method B of a modified PVA-based composite fiber melt-blown cloth; the preparation method A comprises the following steps: dissolving PVA powder in water, adding natural organic acid and ethanol, uniformly mixing and carrying out organic acid modification; ion doping is carried out on the mixed solution in step (1) through an ionic compound solution to obtain a modified PVA solution; the modified PVA solution is electrospun to obtain a modified PVA film; the preparation method B comprises the following steps: weighing PVA, natural organic acid and ionic compound solid powder, uniformly mixing, melting, cooling, drawing, setting and forming into a fiber, preparing a net-shaped fiber layer and preparing the modified PVA-based composite fiber melt-blown cloth.The mask material prepared by ion doping and natural organic acid modification on the PVA film has the characteristics of moisture resistance, swelling resistance, strong static adsorption and degradability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of textile materials, and particularly relates to a preparation method of a moisture-resistant and swelling-resistant degradable mask material. BACKGROUND

[0002] N95 respirators and medical masks are important personal protective equipment for preventing and inhibiting the spread of highly infectious viruses. At present, the most commonly used masks are N95 respirators and medical masks, which contain a thin layer of polypropylene (PP) melt-blown fabric to filter out particles and droplets. Usually, the surface of the PP fabric is negatively charged by electrostatic charging technology to capture charged particles, thereby improving the filtration efficiency of the mask. However, long-term wearing of the mask can significantly reduce the efficiency of filtering bacteria, viruses and other droplets, and it is recommended that N95 respirators be limited to five times of reuse, and medical masks be replaced every 2 to 4 hours. Therefore, a large number of discarded masks are generated, and the PP melt-blown fabric is difficult to degrade, and the pollutants generated during the incineration of waste plastics can cause serious environmental problems. Therefore, how to avoid the reduction of filtration efficiency and reduce the pollution of discarded masks to the environment is a major problem.

[0003] The main reason for the reduction of the filtration efficiency of bacteria, viruses and other droplets of the mask during use is that the moisture in the air exhaled by the human body can quickly attenuate or neutralize the charge on the PP, thereby losing the ability to capture charged particles (including bacteria and viruses). In view of this problem, Wang et al. used a polyvinyl alcohol (PVA) electrospun net to replace the inner layer of the PP melt-blown net to prepare a new type of medical mask with self-charging and charge retention performance in a high humidity environment (Adv. Funct. Mater. 2021, 31, 2009172). This new type of medical mask is a triboelectric nanogenerator composed of an outer layer of PP and an inner layer of PVA. The water molecules fixed by PVA through hydrogen bonds can participate in the triboelectric process due to their high electropositivity, thereby increasing the charge of the medical mask. This medical mask with PVA as the internal adsorption layer has the characteristics of self-charging and high moisture resistance, and after the charge is dissipated during long-term wearing, the PVA surface can be fully charged by hand tapping without taking off the mask.

[0004] However, pure PVA is prone to swelling in a humid environment due to its hydrophilicity and has poor mechanical properties, which can easily cause the filtration performance to deteriorate during use. In addition, the water absorption and swelling of PVA can also greatly affect the electrostatic adsorption capacity of the PVA film in a high humidity environment. Therefore, it is urgent to design a PVA-based mask air filtration film or melt-blown cloth that is moisture-resistant, swelling-resistant, degradable and has strong electrostatic adsorption. SUMMARY

[0005] The application discloses a preparation method of a moisture-resistant and swelling-resistant degradable mask material, and aims to ion dope and modify PVA film with natural organic acid, improve the moisture resistance, swelling resistance and electrostatic adsorption capacity under high humidity, so as to provide a moisture-resistant, degradable and strong electrostatic adsorption air filter film and melt-blown cloth for a mask product.

[0006] To achieve the above-mentioned purpose, the technical scheme of the application is:

[0007] A preparation method of a moisture-resistant and swelling-resistant degradable mask material, comprising a preparation method A of a mask air filter film and a preparation method B of a modified PVA-based composite fiber melt-blown cloth.

[0008] The preparation method A comprises the following steps:

[0009] (1) dissolving PVA powder in water at 80-90 DEG C to completely dissolve, then adding natural organic acid and ethanol to mix uniformly, and modifying with the organic acid;

[0010] (2) dissolving an ionic compound in water, then adding the obtained solution into the mixed solution in step (1) to ion dope, and uniformly mixing to obtain a modified PVA solution;

[0011] (3) loading the modified PVA solution into a syringe of an electrospinning machine to perform electrospinning, and obtaining a modified PVA film;

[0012] The preparation method B comprises the following steps: accurately weighing PVA powder, natural organic acid powder and ionic compound solid powder, uniformly mixing, placing in a screw extruder to melt the mixture, then cooling and drawing the melt through a drawing air duct to form fibers, uniformly adsorbing the fibers to a screen curtain of a web former through a diffusion air duct to form a continuous fibrous layer, and preparing the continuous fibrous layer into a cloth by using a hot calender to obtain a modified PVA-based composite fiber melt-blown cloth.

[0013] Preferably, in step (1), the natural organic acid comprises one or more of tannic acid, tartaric acid, oxalic acid, citric acid, salicylic acid and phytic acid.

[0014] Preferably, in step (1), the natural organic acid is tannic acid.

[0015] Preferably, in step (2), the ionic compound comprises one or more of sodium chloride, lithium chloride, calcium chloride, zinc chloride, aluminum chloride, iron chloride, sodium sulfate, copper sulfate and sodium alginate.

[0016] Preferably, in step (2), the ionic compound is calcium chloride.

[0017] Preferably, in the step (2), the mass percentage of PVA in the modified PVA solution is 10-20% of the total mass of the modified PVA solution, the mass percentage of the ionic compound is 1-5% of the total mass of the modified PVA solution, and the mass percentage of the natural organic acid is 1-5% of the total mass of the modified PVA solution.

[0018] Preferably, in the step (3), the electrostatic spinning machine is a drum type spinning machine, and finally, the modified PVA composite film and the polytetrafluoroethylene PTFE film are assembled into a friction nanogenerator.

[0019] Preferably, in the preparation method B, the natural organic acid powder is tannic acid, and the ionic compound powder is anhydrous calcium chloride.

[0020] Preferably, in the preparation method B, the mass ratio of PVA powder, tannic acid powder and anhydrous calcium chloride is 4:1:1.

[0021] The preparation method of the moisture-resistant and swelling-resistant degradable mask material has the following advantages:

[0022] 1. The polyvinyl alcohol material selected in the application is a degradable polymer material, and the modified PVA modified film and the modified PVA-based composite fiber melt-blown cloth prepared after modification are still degradable, which can alleviate the pollution of discarded masks to the environment.

[0023] 2. The PVA modified film and the modified PVA-based composite fiber melt-blown cloth prepared in the application have low swelling degree in high humidity environment, can significantly improve the filtration performance in high humidity, and have excellent mechanical properties in high humidity.

[0024] 3. The PVA modified film and the modified PVA-based composite fiber melt-blown cloth prepared in the application have higher electrostatic adsorption capacity than pure PVA in high humidity, and can effectively and long-term adsorb charged particles (bacteria and viruses, etc.) in the air.

[0025] 4. The PVA modified film and the modified PVA-based composite fiber melt-blown cloth prepared in the application have simple preparation process, the cost of per kilogram of polyvinyl alcohol is about 10 yuan, the use cost is low, and it is easy to mass produce. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flow chart of the preparation method A of the application.

[0027] Figure 2 The flow chart of the preparation method B of the application.

[0028] Figure 3 The scanning electron microscope picture of the mask air filtration film prepared by the electrospinning method.

[0029] Figure 4 Swelling degree comparison chart of pure PVA film and modified PVA film.

[0030] Figure 5 Stress-strain curve of pure PVA film and modified PVA film.

[0031] Figure 6 Charge amount comparison chart of pure PVA film and modified PVA film.

[0032] 01. PVA powder, 02. Tannic acid powder, 03. Anhydrous calcium chloride powder, 04. Screw extruder, 05. Melt-blowing nozzle, 06. Web former, 07. Single-layer fiber formed by cooling, drawing and setting, 08. Continuous web-shaped fiber layer; 1. PVA solution dissolved in water, 2. Mixed solution of PVA and tannic acid, 3. Ion-doped modified PVA solution, 4. Modified PVA film prepared by electrospinning method. DETAILED DESCRIPTION

[0033] The following description is only the preferred embodiment of the present application, and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0034] Example 1

[0035] A preparation method of a moisture-resistant and swelling-resistant degradable mask material, comprising the following steps:

[0036] (1) Dissolve PVA powder in water at 80-90℃ to completely dissolve, then add natural organic acid and ethanol to mix uniformly, and perform organic acid modification;

[0037] (2) Dissolve ionic compound in water, then add the obtained solution to the mixed solution of step (1) to perform ion doping, and obtain colorless or light yellow modified PVA solution after mixing uniformly;

[0038] (3) Put the modified PVA solution into the needle cylinder of the electrospinning machine to perform electrospinning, and obtain modified PVA film.

[0039] Example 2

[0040] In the step (1), the natural organic acid includes one or more of tannic acid, tartaric acid, oxalic acid, citric acid, salicylic acid and phytic acid.

[0041] In the embodiment, the natural organic acid is preferably tannic acid.

[0042] Example 3

[0043] The ion compound in step (2) includes one or more of sodium chloride, lithium chloride, calcium chloride, zinc chloride, aluminum chloride, iron chloride, sodium sulfate, copper sulfate, and sodium alginate.

[0044] In this embodiment, the ion compound is preferably calcium chloride.

[0045] Example 4

[0046] In step (2), the mass ratio of PVA in the modified PVA solution is 10% of the total mass of the modified PVA solution, the mass ratio of the ion compound is 1% of the total mass of the modified PVA solution, and the mass ratio of the natural organic acid is 1% of the total mass of the modified PVA solution.

[0047] Example 5

[0048] In step (2), the mass ratio of PVA in the modified PVA solution is 20% of the total mass of the modified PVA solution, the mass ratio of the ion compound is 5% of the total mass of the modified PVA solution, and the mass ratio of the natural organic acid is 5% of the total mass of the modified PVA solution.

[0049] Example 6

[0050] First, 4g of PVA powder (10wt%) was dissolved in 20g of deionized water and stirred uniformly at 90℃. Then the PVA solution was cooled to room temperature, 1g of tannic acid powder (2.5wt%) and ethanol were added. 1g of anhydrous CaCl2 powder (2.5wt%) was dissolved in 10g of deionized water, and after stirring uniformly, it was added to the mixed PVA solution, and ultrasonic stirring was carried out for 2h until a light yellow modified PVA solution was obtained. The modified PVA solution was loaded into a 10ml syringe, and electrospinning was carried out to obtain a modified PVA film. The electrospinning machine used was a roller type spinning machine, and the spinning parameters were set as follows: spinning distance 15cm, voltage 25kV, and spinning speed 0.2mL / h. Finally, the modified PVA composite film and PTFE film were assembled into a friction nanogenerator.

[0051] The prepared film was vacuum dried at room temperature for 2 h to obtain its dry weight. Then, the dried film was immersed in deionized water at room temperature for 24 h until reaching the swelling equilibrium. After quickly removing the water on the surface, the swollen film was re-weighed to measure its swelling degree. The microstructure of the prepared PVA modified film was observed by field emission scanning electron microscope. The mechanical tensile test was performed using a universal testing machine, and the friction and wear experiment was performed using a friction and wear testing machine to characterize the mechanical properties and tribological properties of the modified film. The short-circuit current and output voltage of the frictional nanogenerator based on the modified PVA film were recorded using a SR-570 low noise current amplifier and a Tek MDO3 oscilloscope (Tektronix, USA) with a high voltage probe, and the charge amount of the pure PVA film and the modified PVA film was measured using a Faraday cylinder to characterize its electrostatic adsorption capacity under high humidity.

[0052] Example 7

[0053] Precisely weigh 10 g of PVA powder, 2.5 g of tannic acid powder and 2.5 g of anhydrous calcium chloride, mix uniformly, place in a screw extruder to melt, then the melt passes through a drawing air duct to cool and draw to form fibers, the fibers are uniformly adsorbed on the screen curtain of the web former after passing through the diffusion air duct to form a continuous fibrous web layer. The continuous fibrous web layer is prepared into a cloth by a hot calender to obtain a modified PVA-based composite fiber melt-blown cloth. The swelling degree, mechanical properties, tribological properties and electrostatic adsorption properties of the modified PVA-based composite fiber melt-blown cloth are tested respectively, with a single-layer polypropylene melt-blown cloth as a control group.

[0054] Working principle of the present application:

[0055] The present application adopts natural organic acid modification and ion compound doping to obtain a modified PVA solution. Taking tannic acid (TA) as an example, TA is water-soluble and biodegradable. TA can combine with proteins through hydrogen bonding and hydrophobic interaction under high humidity, can penetrate the bacterial cell wall to kill bacteria, so that the PVA fiber has antibacterial properties. At the same time, TA can act as a physical and chemical crosslinking agent through intermolecular interaction (such as hydrogen bonding, ionic bonding and π-π interaction) to enhance the mechanical properties and tribological properties of the fiber. Taking CaCl2 as an example, CaCl2 can form O-Ca-O interchain crosslinking with the hydroxyl groups of PVA, reduce the swelling degree of PVA fiber after water, improve the water resistance of the fiber, and prevent the reduction of gas permeation rate. At the same time, the doping of CaCl2 can further improve the mechanical properties and tribological properties of the fiber. In addition, the doping of CaCl2 can enhance the triboelectric output of the PVA fiber under high humidity and improve the electrostatic adsorption capacity of the fiber film.

[0056] The raw material required by the application has low cost, simple preparation method, easy large-scale production, and is a degradable material without environmental pollution. The preparation process is carried out under the condition of water and ethanol as solvent, and the highest temperature only needs 90 DEG C, and the voltage of electrostatic spinning is 25kV. The preparation method provided by the application can not only use electrostatic spinning method to prepare PVA fiber membrane (filter membrane), but also use melt blowing method to prepare PVA melt blowing cloth, which can be used as mask material.

[0057] The conventional PP melt blown cloth is charged by electrostatic polarization technology to capture charged particles. In addition to the above-mentioned mode, the fiber membrane prepared by the application can also inject electric charge into the PVA fiber by tribocharging during use and normal breathing process, realize self-charging of the PVA fiber, and have high charge retention capacity under high humidity, thereby improving the service life and electrostatic adsorption capacity of the mask under high humidity.

Claims

1. A method for preparing a moisture-resistant, swelling-resistant, and biodegradable mask material, characterized by: Method B includes the preparation method of modified PVA-based composite fiber meltblown fabric; The preparation method B includes the following steps: accurately weighing PVA powder, natural organic acid powder and ionic compound solid powder, mixing them evenly, placing them in a screw extruder to melt the mixture, then cooling and stretching the melt through a stretching air duct to form fibers, and then uniformly adsorbing the fibers onto the screen of a web forming machine after passing through a diffusion air duct to form a continuous mesh fiber layer, and using a hot rolling mill to prepare the continuous mesh fiber layer into a fabric to obtain modified PVA-based composite fiber meltblown fabric; In preparation method B, the natural organic acid powder is tannic acid, and the ionic compound powder is anhydrous calcium chloride. In the preparation method B, the mass ratio of PVA powder, tannic acid powder, and anhydrous calcium chloride is 4:1:1.

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