Electrostatically assisted high-voltage flash spinning three-dimensional non-woven material, and preparation method therefor

Abstract

The application belongs to the technical field of non-woven materials, and discloses an electrostatically assisted high-voltage flash spinning three-dimensional non-woven material, and a preparation method therefor. In the preparation method, an electrostatically assisted high-voltage flash spinning process is used for material preparation. During the preparation, the effect of an electrostatic field force is incorporated, enabling the effective regulation of and control over the arrangement and distribution of micro-nano fibers within the prepared three-dimensional non-woven material, thereby reducing the occurrence of uneven fiber dispersion or of the agglomeration of filament fibers. In addition, the prepared three-dimensional non-woven material exhibits good mechanical properties, moisture permeability and barrier properties. The preparation method exhibits high preparation efficiency and can realize continuous large-scale production.

Description

An electrostatically assisted high-voltage flash-blown three-dimensional nonwoven material and its preparation method Technical Field

[0001] This application relates to the field of nonwoven materials technology, specifically to an electrostatically assisted high-voltage flash spray three-dimensional nonwoven material and its preparation method. Background Technology

[0002] In existing technologies, nonwoven materials are widely used, especially in the field of medical protective equipment (such as medical masks), where they have largely replaced traditional materials as the main material. Among nonwoven materials, high-pressure flash-blown nonwoven materials have better mechanical and sealing properties. Therefore, the application prospects of high-pressure flash-blown nonwoven materials are better than those of other types of nonwoven materials.

[0003] The general process for preparing high-pressure flash-blown nonwoven materials is as follows: A polymer is dissolved in a solvent under high temperature and pressure to obtain a spinning solution. Then, through instantaneous temperature and pressure loss, the polymer and solvent in the spinning solution undergo phase separation, leading to solvent evaporation and the formation of micro / nano-scale monofilament bundles. Finally, the product is prepared through processes such as filament splitting, web formation, and high-temperature hot rolling. However, unlike melt-blown nonwoven materials, the monofilaments of high-pressure flash-blown nonwoven materials prepared by the above method are mostly at the micro / nano scale. Therefore, it is difficult to achieve controllable splitting and orderly arrangement of the filament bundles solely relying on the high-pressure airflow field. This results in defects such as uneven filament splitting, poor mechanical properties, and poor barrier properties in the prepared product. Summary of the Invention

[0004] Based on the deficiencies of existing technologies, the purpose of this application is to provide a method for preparing three-dimensional nonwoven materials. This method uses an electrostatic assisted high-pressure flash spray process to prepare materials. During the preparation process, the effect of electrostatic field force is introduced, which can effectively control the arrangement and distribution of micro and nanofibers in the prepared three-dimensional nonwoven materials. Moreover, the three-dimensional nonwoven materials have excellent performance.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0006] A method for preparing a three-dimensional nonwoven material includes the following steps:

[0007] (1) Prepare the high-pressure flash-jet spinning solution;

[0008] (2) After connecting a positive voltage of 5 to 40 kV to the spinneret of the high-pressure flash jet device, set the spinning pressure to 5 to 30 kPa and start spinning; collect the spun yarn with a spinning receiving device, which is a metal tape with a hollow hole structure, and the tape is connected to the ground wire or a negative voltage of -5 to -40 kV.

[0009] (3) The collected filaments are hot rolled to obtain a three-dimensional nonwoven material.

[0010] In the process of preparing nonwoven materials using high-pressure flash spraying technology, the uniformity and dispersion of the fibers in the resulting material are controlled solely by the force of the high-pressure airflow field. Due to the poor stability of this high-pressure airflow field, the quality of nonwoven materials prepared by existing high-pressure flash spraying technology is difficult to achieve the expected results. Electrospinning technology is a technique that can prepare highly uniform three-dimensional fiber materials through electrostatic force, but because the effect of electrostatic force is limited and the product is collected by roller-type or flat-plate receiving devices, this technology cannot achieve continuous and effective large-scale production and uniform production. In the method described in this application, the inventors combine high-pressure flash spraying technology and electrospinning technology. Positive and negative voltages (or ground wires) are respectively set on the high-pressure flash spraying device and the receiving device. This allows the spun fibers to be subjected to both high-pressure airflow and electrostatic force, thus achieving dual control over the arrangement, distribution, and uniformity of the sprayed fibers, reducing the occurrence of inconsistent fiber lengths or long fiber agglomeration. Simultaneously, the traditional receiving device is replaced with a metal assembly belt with a perforated structure. After connecting to the ground wire or negative voltage, under the action of the electrostatic force, the spun fibers, when collected on the metal assembly belt, further exhibit a specific three-dimensional structure, resulting in fibers of moderate size with high strength and uniformity. The final product obtained after hot rolling (i.e., three-dimensional nonwoven material) exhibits excellent mechanical properties, moisture permeability, and barrier properties.

[0011] Preferably, the positive voltage in step (2) is any one of 5kV, 6kV, 8kV, 10kV, 12kV, 15kV, 20kV, 25kV, 30kV, 35kV, and 40kV, or a range of any two.

[0012] Preferably, the spinning pressure in step (2) is set to any one of 5 kPa, 8 kPa, 10 kPa, 12 kPa, 15 kPa, 18 kPa, 20 kPa, 22 kPa, 25 kPa, 28 kPa, 30 kPa, or a range of any two.

[0013] It should be noted that the spinning pressure set in this application refers to the pressure of the high-pressure flash-jet spinning solution when it enters the spinneret.

[0014] When performing high-pressure flash-jet spinning, the set voltage and spinning pressure have a significant impact on the continuity and strength of the prepared spun yarn. When the set conditions within the above-mentioned preferred range are selected, the overall performance of the prepared product is better.

[0015] Preferably, the high-pressure flash-spinning solution in step (1) comprises the following components in parts by weight: 2 to 15 parts of polymer and 85 to 98 parts of solvent; wherein the polymer is at least one of polyethylene and polypropylene, and the solvent is at least one of dichloromethane and trichloromethane.

[0016] Preferably, the temperature of the high-pressure flash-spinning solution in step (1) is 150–300°C.

[0017] Using a suitable temperature during high-pressure flash spinning allows the materials in the solution to dissolve and disperse fully, resulting in better continuity of the prepared fiber web filaments and superior overall performance of the obtained three-dimensional nonwoven material.

[0018] More preferably, the preparation method of the high-pressure flash-spinning solution in step (1) is as follows: the polymer and solvent are mixed, then heated and mixed at a pressure of 5 to 30 kPa for 1 to 3 hours to obtain the high-pressure flash-spinning solution.

[0019] Preferably, the receiving distance of the spinning receiving device in step (2) is 10 to 120 cm.

[0020] Preferably, the receiving distance of the spinning receiving device in step (2) is 15 to 100 cm.

[0021] More preferably, the receiving distance of the spinning receiving device in step (2) is any one of 15cm, 20cm, 25cm, 30cm, 35cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, and 100cm, or a range of any two.

[0022] It should be noted that the receiving distance of the spinning receiving device described in this application refers to the straight-line distance from the spinneret of the high-pressure flash jet device to the spinning receiving device.

[0023] Preferably, the pore density of the perforated structure of the metal strip in step (2) is 20 to 150 mesh.

[0024] Preferably, the pore density of the perforated structure of the metal strip in step (2) is 50 to 100 mesh.

[0025] More preferably, the pore density of the perforated structure of the metal strip in step (2) is any one of 50 mesh, 60 mesh, 65 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, or any two of them.

[0026] During the spinning process, the porosity of the metal strip affects the airflow through the perforated structure, which in turn impacts the spinning web-forming effect and uniformity. Within the preferred porosity range, the web-formed product exhibits superior quality after hot rolling.

[0027] Preferably, the metal strip in step (2) is at least one of stainless steel strip, copper strip, and aluminum strip.

[0028] Preferably, the transmission speed of the metal tape in step (2) is 0.5 to 5 m / min.

[0029] Preferably, the hot rolling temperature in step (3) is 50 to 100°C.

[0030] Another objective of this application is to provide a method for preparing the aforementioned three-dimensional nonwoven material to obtain the three-dimensional nonwoven material.

[0031] Another object of this application is to provide the application of the aforementioned three-dimensional nonwoven material in the preparation of medical protective equipment.

[0032] Preferably, the medical protective equipment includes medical masks and medical diaphragms.

[0033] The beneficial effects of this application are that it provides a three-dimensional nonwoven material and its preparation method. This preparation method uses an electrostatically assisted high-pressure flash spray process to prepare the material. During the preparation process, based on the combined effect of electrostatic force and high-pressure airflow force, the arrangement and distribution of micro- and nanofibers in the prepared product can be effectively controlled, reducing phenomena such as uneven fiber dispersion or filament agglomeration. Moreover, the prepared three-dimensional nonwoven material possesses excellent mechanical properties, moisture permeability, and barrier properties. Furthermore, the preparation method has high efficiency and can achieve continuous large-scale production. Attached Figure Description

[0034] Figure 1 is a flowchart of the preparation method of the three-dimensional nonwoven material described in this application, wherein 1 is a high-pressure reactor, 2 is a high-pressure flash-jet spinning solution guide pipe, 3 is a high-pressure flash-jet device spinneret, 4 is connected to positive voltage, 5 is generated spinning, 6 is connected to negative voltage, 7 is a metal accumulation strip, 8 is a hot rolling lower roller, and 9 is a hot rolling upper roller.

[0035] Figure 2 shows the copper metal strip used in the method described in Embodiment 17 of this application. Detailed Implementation

[0036] To better illustrate the purpose, technical solution, and advantages of this application, the following description, in conjunction with specific embodiments and comparative examples, aims to provide a detailed understanding of the content of this application, rather than limiting it. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this application. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this application are all commonly used reagents and instruments.

[0037] Examples 1-16

[0038] Several embodiments of the preparation method of the three-dimensional nonwoven material described in this application are provided. A schematic flowchart of the preparation method is shown in Figure 1, which includes the following steps:

[0039] (1) Prepare the high-pressure flash-jet spinning solution;

[0040] (2) After connecting a positive voltage of AkV to the spinneret of the high-pressure flash jet device, set the spinning pressure to B kPa and start spinning; collect the spun yarn using a spinning receiving device, which is a metal assembly tape with a perforated structure, connected to ground or a negative voltage of C kV; the receiving distance of the spinning receiving device is D cm, the metal assembly tape is a stainless steel assembly tape with a pore density of E mesh, and the transmission speed is 10 m / min. The specific parameters of Examples 1-16 are shown in Table 1.

[0041] (3) The collected spun yarn is hot rolled at 70°C to obtain a three-dimensional nonwoven material.

[0042] The preparation method of the high-pressure flash-jet spinning solution in step (1) includes the following steps:

[0043] 2500g of dichloromethane solvent and 200g of polyethylene powder were added to a high-pressure reactor, heated to 200℃, and mixed at 8MPa pressure for 2h to obtain a high-pressure flash-spinning solution.

[0044] The polyethylene powder is GUR4116, manufactured by Celanese Corporation of the United States.

[0045] Example 17

[0046] A method for preparing the three-dimensional nonwoven material described in this application is provided, the steps of which are the same as those in Example 1, and the parameters involved are shown in Table 1, with the only difference being:

[0047] (a) The method for preparing the high-pressure flash-jet spinning solution in step (1) of this embodiment includes the following steps:

[0048] 1500g of dichloromethane solvent, 1500g of trichloromethane solvent, and 300g of polyethylene powder were added to a high-pressure reactor, heated to 200℃, and mixed at 8MPa pressure for 3 hours to obtain a high-pressure flash-spinning solution.

[0049] (b) The metal strip in this embodiment is a copper strip, as shown in Figure 2.

[0050] Table 1

[0051] Comparative Examples 1-4

[0052] A method for preparing a three-dimensional nonwoven material differs from Example 1 only in that the process parameters in Table 1 are different.

[0053] It should be noted that in Comparative Example 1, "A voltage" is " / ", indicating that a positive voltage is not connected to the spinneret of the high-voltage flash spray device; in Comparative Example 4, "E mesh number" is " / ", indicating that the metal strip is a solid structure and does not have a perforated structure.

[0054] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this application are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0055] Example of effect 1

[0056] To verify the performance of the three-dimensional nonwoven materials prepared by the method described in this application, the products of each embodiment and comparative example were subjected to the following performance tests:

[0057] (1) Tensile strength before hot rolling: The three-dimensional nonwoven material before hot rolling was tested according to the Chinese national standard GB / T 3923.1-1997. The sample was 50×150mm and the tensile speed was 100mm / min.

[0058] (2) Tensile strength after hot rolling: After hot rolling, the tensile strength of the three-dimensional nonwoven material was tested using the same method as in (1);

[0059] (3) Moisture permeability: The three-dimensional nonwoven material after hot rolling was tested according to the Chinese national standard GB / T19082-2009 at 38℃ and 90% relative humidity (RH);

[0060] (4) Water pressure resistance: The hot-rolled three-dimensional nonwoven material was tested according to the international standard EN ISO 811:2018, with a pressure increase rate of 60cm H2O / min.

[0061] The test results are shown in Table 2.

[0062] Table 2

[0063] As can be seen from Table 1, the three-dimensional nonwoven material prepared by the method described in this application has ideal comprehensive properties. Before hot rolling, the tensile strength of the three-dimensional nonwoven material can reach over 9.5 N / 50 m, while after hot rolling, the tensile strength can reach over 250 N / 50 m, demonstrating excellent mechanical properties. Regarding moisture permeability and water pressure resistance, the moisture permeability of the three-dimensional nonwoven material can reach 3500 g / m³. 2 With a lifespan of over 24 hours and a water pressure resistance of over 20 kPa, its performance is equally ideal.

[0064] In the product preparation process, since the process described in this application combines high-pressure flash spray technology and electrospinning technology, the setting of voltage and spinning pressure is the most critical. Regarding voltage setting, as can be seen from Examples 1-4 and Comparative Examples 1-2, without voltage setting, the product in Comparative Example 1 is prepared solely by the high-pressure flash spray process. The preparation process relies solely on the high-pressure airflow field force to control the uniformity and dispersion of the spun fibers, which obviously cannot achieve the expected results. The tensile strength, moisture permeability, and water pressure resistance of the prepared product are all poor. With the voltage setting, the electrostatic field force appears during the preparation process, and all the product's indicators are significantly improved. Especially when the voltage is set in the range of 15-30kV, the resulting product has better tensile strength, moisture permeability, and water pressure resistance after hot rolling. However, if the voltage is set too high, as shown in Comparative Example 2, the electrostatic field force will have a counteracting effect on the uniformity and dispersion of the spun fibers, and the product's performance will significantly decrease. Regarding the setting of spinning pressure, as can be seen from Examples 1, 5-7, and Comparative Example 3, the magnitude of the spinning pressure also affects the quality of the spun fibers, and consequently, the performance of the final product, compared to the electrostatic field force. Both the high-pressure airflow force and the electrostatic field force need to be maintained at appropriate levels; otherwise, as shown in Comparative Example 3, excessive spinning pressure can lead to a decline in various aspects of the product's performance. For example, the tensile strength and other properties after hot rolling may even be similar to those of the product in Comparative Example 1, which does not have an applied electrostatic field force.

[0065] On the other hand, after setting the voltage and spinning pressure, the receiving distance of the spinning receiving device during spinning will also affect the receiving and web-laying effect of the spinning. As can be seen from Examples 1 and 8-12, the performance indicators of the product also change with the change of the receiving distance. When the receiving distance is set to 15-100cm, the product performance is better.

[0066] As a spinning receiving device, this application utilizes a process technology based on electrostatic-high-voltage flash-jet combined spinning, requiring the use of a metal assemblies with a perforated structure. Under this perforated structure, airflow can flow fully during spinning reception, ensuring the uniformity and high dispersion of fibers in the product, preventing adhesion, and resulting in excellent performance after hot rolling. Otherwise, as can be seen from the product in Comparative Example 4, using a conventional solid metal assemblies as a receiving device leads to poor web-laying effect, and the performance of the final product is naturally inferior. Furthermore, as shown in Examples 1 and 13-16, the pore density of the perforated structure also affects the product performance; a mesh size of 50-100 mesh is preferred, resulting in a better final product performance.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A method for preparing a three-dimensional nonwoven material, comprising the following steps: (1) Prepare the high-pressure flash-jet spinning solution; (2) After connecting a positive voltage of 5 to 40 kV to the spinneret of the high-pressure flash jet device, set the spinning pressure to 5 to 30 kPa and start spinning; collect the spun yarn with a spinning receiving device, which is a metal tape with a hollow hole structure, and the tape is connected to the ground wire or a negative voltage of -5 to -40 kV. (3) The collected filaments are hot rolled to obtain a three-dimensional nonwoven material.

2. The method for preparing the three-dimensional nonwoven material according to claim 1, wherein the high-pressure flash-spinning solution in step (1) comprises the following components in parts by weight: 2 to 15 parts of polymer and 85 to 98 parts of solvent; wherein the polymer is at least one of polyethylene and polypropylene, and the solvent is at least one of dichloromethane and trichloromethane.

3. The method for preparing three-dimensional nonwoven materials as described in claim 1 or 2, wherein the temperature of the high-pressure flash-spinning solution in step (1) is 150 to 300°C.

4. The method for preparing three-dimensional nonwoven materials according to any one of claims 1-3, wherein the receiving distance of the spinning receiving device in step (2) is 10-120cm.

5. The method for preparing a three-dimensional nonwoven material according to any one of claims 1-4, wherein the pore density of the hollow hole structure of the metal tape in step (2) is 20-150 mesh.

6. The method for preparing the three-dimensional nonwoven material according to any one of claims 1-5, wherein the metal tape in step (2) is at least one of stainless steel tape, copper tape, and aluminum tape.

7. The method for preparing a three-dimensional nonwoven material according to any one of claims 1-6, wherein the transmission speed of the metal tape in step (2) is 0.5-5 m / min.

8. The method for preparing a three-dimensional nonwoven material according to any one of claims 1-7, wherein the hot rolling temperature in step (3) is 50-100°C.

9. The three-dimensional nonwoven material prepared by the method for preparing three-dimensional nonwoven materials according to any one of claims 1 to 8.

10. The application of the three-dimensional nonwoven material as described in claim 9 in the preparation of medical protective equipment.

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