Two-component helical micro-nanofiber nonwoven material, method of making and use thereof

Abstract

The present application belongs to the field of textile technology, and relates to a kind of bicomponent spiral micro-nano fiber nonwoven material and its preparation method and application.Bicomponent spiral micro-nano fiber nonwoven material is electrospinning nanofiber membrane, containing bicomponent spiral micro-nano fiber, bicomponent spiral micro-nano fiber is composed of coaxial sheath and core layer, the pitch p of spiral is 1.5-4 μm;Preparation method is to select electrospinning nozzle with three-layer coaxial structure, high-speed airflow, sheath spinning solution, core layer spinning solution are respectively corresponding to continuously sent to the outer layer, middle layer and inner layer of electrospinning nozzle, electrospinning is carried out, bicomponent spiral micro-nano fiber nonwoven material is obtained;Application is to use bicomponent spiral micro-nano fiber nonwoven material as filter material.The present application promotes the efficient and continuous preparation of bicomponent spiral micro-nano fiber nonwoven material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of textiles, and relates to a kind of bicomponent spiral micro-nano fiber nonwoven material and its preparation method and application. BACKGROUND

[0002] Electrospinning, as a kind of process technology that makes polymer solution charged and stretched to micro-nano scale by high-voltage electrostatic field force, has the advantages of simple equipment, low cost and simple process, and is widely used to prepare micro-nano fiber materials. In recent years, with the continuous development of electrospinning technology and the continuous expansion of its application field, single morphology or single component polymer micro-nano fiber has been unable to meet the higher level application requirements for its structure and performance.

[0003] Multi-component electrospinning is a technical means for preparing micro-nano fibers with different morphological structures by spinning two or more polymers at the same time. Among them, the multi-component electrospinning technology can also be used to prepare micro-nano fiber materials with spiral structure. Due to the unique structural advantages of spiral micro-nano fibers, they have potential application prospects in adsorption, filtration, tissue engineering, etc.

[0004] Among the known technologies for preparing spiral micro-nano fibers at present, a variety of researches on using bicomponent electrospinning technology to prepare spiral micro-nano fiber materials have been disclosed, but the existing bicomponent electrospinning method in the preparation of spiral micro-nano fibers faces the following problems:

[0005] (1) The spiral pitch of the spiral micro-nano fiber in the existing technology is small (not more than 1.5 μm), the fiber diameter is large (0.4-0.5 μm), the spiral fibers are seriously adhered, and the spiral structure of the fiber cannot play its unique three-dimensional spiral structure with large specific surface area;

[0006] (2) The prior art such as document (Materials Science and Engineering C-Materials for Biological Applications, 92, 1075 (2018).) and document (Journal of Environmental Chemical Engineering, 10 (2022).) electrospinning has challenges in large-scale production of micro-nano fiber non-woven materials, and cannot be applied to subsequent application performance research of spiral micro-nano fibers. The spiral micro-nano fiber non-woven material in the prior art is prepared by doping metal salt in the polymer solution, which significantly improves the electrical conductivity of the polymer solution. On the one hand, the composite jet formed thereby is adhered to the fibers already deposited on the receiving device due to the presence of a large number of residual charges in the variable process, affecting the continuity and stability of the spinning; on the other hand, after the addition of the metal salt, the surface tension of the polymer increases, and the polymer droplets cannot form a jet, but are aggregated into droplets, which splash onto the fiber membrane already deposited on the receiving device, affecting the surface uniformity of the spiral micro-nano fiber non-woven material. SUMMARY

[0007] The purpose of the present application is to solve the problems existing in the prior art and provide a bicomponent spiral micro-nano fiber non-woven material and a preparation method and application thereof.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0009] A bicomponent spiral micro-nano fiber non-woven material is an electrospun nanofiber membrane containing bicomponent spiral micro-nano fibers, which are composed of a coaxial sheath layer and a core layer. The pitch p of the spiral is 1.5-4 μm, which is significantly higher than the prior art (not more than 1.5 μm), and the spiral radius r is 0.6-1.4 μm (the pitch p and the spiral radius r are as shown in the figure). Figure 1

[0010] As a preferred technical solution:

[0011] The bicomponent spiral micro-nano fiber non-woven material as described above has a diameter of 0.33-0.41 μm, which is significantly lower than the prior art (0.4-0.5 μm).

[0012] The bicomponent spiral micro-nano fiber non-woven material as described above has a sheath layer made of thermoplastic polyurethane (TPU) and a core layer made of cellulose acetate (CA).

[0013] The bicomponent spiral micro-nano fiber non-woven material as described above has a content of bicomponent spiral micro-nano fibers of 50 wt% or more. ​

[0014] The application also provides a method for preparing the bi-component spiral micro-nano fiber non-woven material as described in any one of the above, selecting an electrospinning nozzle with a three-layer coaxial structure, continuously sending a high-speed airflow, a skin layer spinning solution and a core layer spinning solution into the outer layer, the middle layer and the inner layer of the electrospinning nozzle respectively, and performing electrospinning, to obtain the bi-component spiral micro-nano fiber non-woven material, wherein the skin layer spinning solution is a spinning solution for forming a skin layer of the bi-component spiral micro-nano fiber, the core layer spinning solution is a spinning solution for forming a core layer of the bi-component spiral micro-nano fiber, the flow rate of the high-speed airflow is 1-5 L / min, if the flow rate of the high-speed airflow is too small, the high-speed airflow cannot strengthen the electric field, and if the flow rate of the high-speed airflow is too high, the bi-component spiral micro-nano fiber will be straightened by the airflow due to a too large pitch.

[0015] As a preferred technical solution:

[0016] In the method described above, the concentration of the polymer in the skin layer spinning solution is 12-15 wt%, and the skin layer spinning solution does not contain metal salt; the concentration of the polymer in the core layer spinning solution is 14-16 wt%, and the concentration of the metal salt is 0.18 wt%. The concentration of the spinning solution is thus set to avoid clogging the needle due to too large concentration, and to avoid too small concentration and low solution viscosity that cannot be spun. Since the conductivity of the solution increases with the addition of the metal salt, the higher conductivity enables the jet to carry more charges and thus generate greater elongation force, so that the jet is stretched more, and the intrinsic shrinkage force generated by the viscoelastic force of the polymer solution also increases accordingly, forming more spiral fibers. The introduction of the airflow field enables the jet to be fully drawn, so that the content of the metal salt can be reduced, and the polymer jet does not form more spiral structures when solidified due to the jet stretching path obtained by the solution conductivity. Therefore, the application can reduce the amount of metal salt added, which is reduced by 90% compared with the prior art, greatly reducing the adverse effects caused by the doped metal salt solution. The flow rate of the skin layer spinning solution and the core layer spinning solution is 1.5-2.5 mL / h. The flow rate of the spinning solution is positively correlated with the flow rate of the high-speed airflow. The flow rate of the spinning solution should not be too large, otherwise the flow rate of the high-speed airflow will also be too high, the bi-component spiral micro-nano fiber will be straightened by the airflow due to a too large pitch, and on the other hand, the spinning solution cannot be fully volatilized and stretched to form small droplets splashing onto the collection device, affecting the performance of the entire airflow bi-component spiral micro-nano fiber non-woven material, especially the pressure drop of the filter. The flow rate of the spinning solution should also not be too small, otherwise the assistance of the airflow cannot achieve the purpose of increasing the yield of spiral fibers.

[0017] In the method described above, the outer diameter of the outer layer of the electrospinning nozzle is 1.6 mm, the outer diameter of the middle layer is 0.86 mm, and the inner diameter of the inner layer of the electrospinning nozzle is 0.3 mm.

[0018] The production of the bicomponent spiral micro-nano fiber non-woven material is 20 g / h -1 .

[0019] The application also provides the use of the bicomponent spiral micro-nano fiber non-woven material according to any one of the above as a filter material.

[0020] As a preferred technical solution:

[0021] According to the use described above, the filter material has a filtration efficiency of 82.3%-85.6% for PM 0.3 μm NaCl particles in the air, and a filtration resistance of 74-76.4 Pa, and the filtration efficiency of the TPU / CA micro-nano fiber non-woven material in the prior art for PM 0.3 μm NaCl particles in the air is 78.5%, and the filtration resistance is 84.3 Pa, and the application is obviously superior to the prior art, and the bicomponent spiral micro-nano fiber non-woven material of the application is a medium-efficiency air filter, on the one hand, due to the large pitch of the bicomponent spiral micro-nano fiber, the spiral fibers are stacked in the thickness direction on the same plane area, and due to the large pitch of the spiral fibers, the spiral fibers are stacked, and the holes formed between the fibers are more, compared with the compact spiral structure, the holes are larger, so that the filtration efficiency is improved while the pressure drop is reduced; on the other hand, due to the small diameter of the bicomponent spiral micro-nano fiber, after the diameter is reduced, the bicomponent spiral micro-nano fiber non-woven material formed by the bicomponent spiral micro-nano fiber can form more hole channels in a limited space, and the filtration efficiency can be improved.

[0022] Invention principle:

[0023] In the application, a three-component electrospinning nozzle is selected, a high-speed airflow is selected as the outermost layer, and polymer solutions are selected for the middle layer and the core layer; in the spinning process, the jet of the middle layer and the core layer is drawn and refined under the simultaneous action of high-voltage electrostatic field force and outer airflow field force, and finally a micro-nano fiber with a spiral morphology is formed.

[0024] In the process of preparing the bicomponent spiral micro-nano fiber non-woven material, the application introduces an airflow field, after introducing the airflow field, the straight line segment of the jet is shorter, under the same spinning process conditions, the jet has a longer movement path, and the volatilization of the solvent is more sufficient, so that the pitch of the spiral is larger, and the spiral structure is adjusted, and the longer jet path allows the fiber charge to dissipate and not to be adhered to the fibers deposited on the receiving device;

[0025] After introducing the airflow field, the shear force at the gas / liquid interface is increased, the solvent evaporation is accelerated, and the fiber diameter is reduced;

[0026] After the introduction of the airflow field, the airflow field and the electric field are compounded, thereby breaking the surface tension of the polymer and increasing the whipping frequency of the jet, so that the production of the bicomponent spiral micro-nano fiber non-woven material is increased from the previous 2g h -1 to about 20gh -1 , reducing the droplet in electrospinning;

[0027] After the introduction of the airflow field, the airflow can increase the volatilization of the solvent, so that the polymer forms a jet without liquid droplets splashing, and the electrostatic interaction between the whipping jet and the deposited fiber is inhibited, reducing the adhesion between the fibers when the fiber settles on the drum, so that the deposited fibers can be uniformly and continuously collected on the receiving device, and the airflow micro-nano spiral non-woven fabric can be mass produced;

[0028] After the introduction of the airflow field, the jet is fully stretched, and after the external force is weakened, the intrinsic shrinkage force generated by the viscoelasticity of the polymer solution also increases accordingly, which will make the polymer jet form more spiral structure when solidified.

[0029] In the prior art, the electrostatic field force, the coulomb force, the viscoelastic force and the surface tension act on the polymer to form a strain difference related to the spiral curvature. Compared with the prior art, the airflow force is added on the basis of the electrostatic field force, the coulomb force, the viscoelastic force and the surface tension in the present application, so that the strain difference related to the spiral curvature is reduced, the spiral curvature is reduced, and the pitch of the spiral is increased under the condition that the spiral radius remains unchanged.

[0030] Advantages:

[0031] (1) Compared with the traditional bicomponent electrospinning for preparing spiral micro-nano fibers, the present application introduces a physical field (airflow field) to assist the preparation of bicomponent spiral micro-nano fiber non-woven material. In the electrospinning process, the airflow field and the electrostatic field are coupled with each other, which promotes the efficient and continuous preparation of bicomponent spiral micro-nano fiber non-woven material.

[0032] (2) Compared with the traditional bicomponent electrospinning for preparing spiral micro-nano fibers, the yield of the bicomponent spiral micro-nano fiber non-woven material of the present application is significantly improved.

[0033] (3) The bicomponent spiral micro-nano fiber of the bicomponent spiral micro-nano fiber non-woven material of the present application has a special spiral three-dimensional structure compared with conventional micro-nano fibers. Compared with the spiral micro-nano fiber of the prior art, the pitch is increased, the fiber diameter is reduced, and the surface area of the material is improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a schematic diagram of the pitch p and the spiral radius r;

[0035] Figure 2 The planar distribution curve of the electric field near the electrospinning nozzle when introducing the airflow field for electrospinning of the present application;

[0036] Figure 3 The axial distribution curve of the electric field near the electrospinning nozzle when introducing the airflow field for electrospinning of the present application;

[0037] Figure 4 Simple device diagram for introducing the airflow field for electrospinning of the present application;

[0038] Figure 5 The electron microscope image of the bicomponent spiral micro-nano fiber in the bicomponent spiral micro-nano fiber non-woven material of Example 1;

[0039] Figure 6 The electron microscope image of the spiral micro-nano fiber of the non-woven material prepared in Comparative Example 1;

[0040] Wherein, 1-high speed airflow, 2-sheath layer spinning solution, 3-core layer spinning solution, 4-electrospinning nozzle. DETAILED DESCRIPTION

[0041] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0042] The following are the test methods for the properties in each example and comparative example:

[0043] Filtering efficiency and filtering resistance: Automatic filter material tester 8130 was used to test according to GB / T 32610-2016 at a flow rate of 32 L / min.

[0044] Example 1

[0045] A preparation method of a bicomponent spiral micro-nano fiber non-woven material, the specific steps are as follows:

[0046] (1) Preparation of raw materials;

[0047] Electrospinning nozzle: with a three-layer coaxial structure, the outer diameter is 1.6 mm, the outer diameter of the middle layer is 0.86 mm, and the inner diameter is 0.3 mm;

[0048] Sheath layer spinning solution: composed of 12wt% TPU (manufacturer Desmopan, brand DP 2590A) and the balance of N-N dimethylformamide;

[0049] Core spinning solution: composed of 14 wt% CA (manufacturer: Sigma, Germany), 0.18 wt% anhydrous lithium chloride and the balance solvent (a mixture of N,N dimethylacetamide and acetone in a volume ratio of 1:2);

[0050] (2) Figure 4 As shown, a high-speed airflow 1 with a flow rate of 3 L / min, a skin spinning solution 2 with a flow rate of 2 mL / h, and a core spinning solution 3 with a flow rate of 2 mL / h are continuously fed into the outer, middle, and inner layers of an electrospinning nozzle 4, respectively, for electrospinning to obtain a bicomponent helical micro / nanofiber nonwoven material. The electrospinning voltage is 25 kV, and the distance between the spinneret and the collecting device is 15 cm. The planar distribution curve of the electric field near the electrospinning nozzle is shown in the figure. Figure 2 As shown, the axial distribution curve of the electric field near the electrospinning nozzle is as follows: Figure 3 As shown.

[0051] The final bicomponent helical micro / nanofiber nonwoven material was an electrospun nanofiber membrane, with a yield of 20 g / h. -1 ,like Figure 5 As shown, the electrospun nanofiber membrane contains 80 wt% bicomponent helical micro / nanofibers. The bicomponent helical micro / nanofibers consist of a coaxial skin and core layer with a diameter of 0.36 μm and a helical pitch p of 2.58 μm.

[0052] An application of a bicomponent helical micro / nanofiber nonwoven material: The bicomponent helical micro / nanofiber nonwoven material prepared in this embodiment is used as a filter material. The filtration efficiency for PM 0.3μm NaCl particles in the air is 83.2%, and the filtration resistance is 74.5Pa.

[0053] Comparative Example 1

[0054] A method for preparing a nonwoven material is basically the same as in Example 1, except that: in step (2), a high-speed airflow is not introduced into the outer layer of the electrospinning nozzle.

[0055] The final nonwoven material is as follows Figure 6 As shown, the yield was lower than that of Example 1, the content of bicomponent helical micro / nanofiber was lower than that of Example 1, the diameter of bicomponent helical micro / nanofiber was larger than that of Example 1, and the pitch p of the helix of the bicomponent helical micro / nanofiber was smaller than that of Example 1.

[0056] The application of a nonwoven material is basically the same as in Example 1, except that the filter material is the nonwoven material of this comparative example. The test results show that the filtration efficiency for PM 0.3μm NaCl particles in the air is less than that in Example 1, and the filtration resistance is greater than that in Example 1.

[0057] Example 2

[0058] A preparation method of a bicomponent spiral micro-nano fiber nonwoven material, the specific steps are as follows:

[0059] (1) Preparation of raw materials;

[0060] Electrospinning nozzle: with a three-layer coaxial structure, the outer diameter of the outer layer is 1.6mm, the outer diameter of the middle layer is 0.86mm, and the inner diameter is 0.3mm;

[0061] The skin layer spinning solution is composed of 15wt% TPU (manufacturer Desmopan, model DP 2590A) and the balance N-N dimethylformamide;

[0062] The core layer spinning solution is composed of 15wt% CA (manufacturer Sigma, Germany), 0.18wt% anhydrous lithium chloride, and the balance solvent (a mixture of N-N dimethylacetamide and acetone in a volume ratio of 1:2);

[0063] (2) A high-speed airflow with a flow rate of 2L / min, a skin layer spinning solution with a flow rate of 2mL / h, and a core layer spinning solution with a flow rate of 2mL / h are respectively continuously fed into the outer layer, middle layer and inner layer of the electrospinning nozzle, electrospinning is carried out, and a bicomponent spiral micro-nano fiber nonwoven material is obtained, wherein the electrospinning voltage is 30kV, and the distance between the spinneret and the collecting device is 15cm.

[0064] The final bicomponent spiral micro-nano fiber nonwoven material is an electrospinning nanofiber membrane, and the yield is 20g h -1 , the electrospinning nanofiber membrane contains 70wt% bicomponent spiral micro-nano fibers, the bicomponent spiral micro-nano fibers are composed of a coaxial skin layer and a core layer, the diameter is 0.39μm, and the pitch p of the spiral is 3.66μm.

[0065] The application of a bicomponent spiral micro-nano fiber nonwoven material, the bicomponent spiral micro-nano fiber nonwoven material prepared in this embodiment is used as a filter material, the filtration efficiency of PM 0.3μm NaCl particles in the air is 82.3%, and the filtration resistance is 74Pa.

[0066] Example 3

[0067] A preparation method of a bicomponent spiral micro-nano fiber nonwoven material, the specific steps are as follows:

[0068] (1) Preparation of raw materials;

[0069] Electrospinning nozzle: with a three-layer coaxial structure, the outer diameter of the outer layer is 1.6mm, the outer diameter of the middle layer is 0.86mm, and the inner diameter is 0.3mm;

[0070] Sheath spinning solution: composed of 15wt% of TPU (manufacturer Desmopan, model DP 2590A) and the rest of N-N dimethylformamide;

[0071] Core spinning solution: composed of 16wt% of CA (manufacturer Sigma, Germany), 0.18wt% of anhydrous lithium chloride and the rest of solvent (a mixture of N-N dimethylacetamide and acetone in a volume ratio of 1:2);

[0072] (2) A high-speed airflow with a flow rate of 3 L / min, a sheath spinning solution with a flow rate of 2 mL / h and a core spinning solution with a flow rate of 2 mL / h are respectively continuously sent to the outer layer, the middle layer and the inner layer of the electrospinning nozzle to perform electrospinning, thereby obtaining a bicomponent spiral micro-nano fiber non-woven material; wherein the voltage of electrospinning is 25 kV, and the distance between the spinneret and the collecting device is 15 cm.

[0073] The final bicomponent spiral micro-nano fiber non-woven material is an electrospinning nanofiber membrane, and the yield is 20 g h -1 The electrospinning nanofiber membrane contains 85wt% of bicomponent spiral micro-nano fibers, the bicomponent spiral micro-nano fibers are composed of coaxial sheath and core layers, the diameter is 0.41 μm, and the pitch p of the spiral is 3.61 μm.

[0074] An application of a bicomponent spiral micro-nano fiber non-woven material, the bicomponent spiral micro-nano fiber non-woven material prepared in this embodiment is used as a filter material, the filtration efficiency of PM 0.3 μm NaCl particles in the air is 85.6%, and the filtration resistance is 76.4 Pa.

Claims

1. A method for preparing a bicomponent helical micro / nanofiber nonwoven material, characterized in that, An electrospinning nozzle with a three-layer coaxial structure is selected. High-speed airflow, skin spinning solution, and core spinning solution are continuously fed into the outer, middle, and inner layers of the electrospinning nozzle, respectively, for electrospinning to obtain a bicomponent helical micro / nanofiber nonwoven material. The flow rate of the high-speed airflow is 1-5 L / min. The bicomponent helical micro / nanofiber nonwoven material is an electrospinned nanofiber membrane containing bicomponent helical micro / nanofibers. The bicomponent helical micro / nanofibers are composed of a coaxial skin layer and a core layer. The helix pitch p is 1.5-4 μm, and the diameter of the bicomponent helical micro / nanofibers is 0.33-0.41 μm. The skin layer is made of thermoplastic polyurethane, and the core layer is made of cellulose acetate. The polymer concentration in the skin spinning solution is 12-15 wt%, and the polymer concentration in the core spinning solution is 14-16 wt%, with a metal salt concentration of 0.18 wt%. The flow rates of both the skin and core spinning solutions are 1.5-2.5 mL / h.

2. The method for preparing a bicomponent helical micro / nanofiber nonwoven material according to claim 1, characterized in that, The outer diameter of the middle layer of the electrospinning nozzle is 0.86 mm, and the inner diameter of the electrospinning nozzle is 0.3 mm.

3. The method for preparing a bicomponent helical micro / nanofiber nonwoven material according to claim 1, characterized in that, The yield of bicomponent helical micro / nanofiber nonwoven material is 20 g / h. -1 .

4. The method for preparing a bicomponent helical micro / nanofiber nonwoven material according to claim 1, characterized in that, The content of bicomponent helical micro / nanofibers is above 50 wt%.

5. The application of the bicomponent helical micro / nanofiber nonwoven material prepared by the preparation method of the bicomponent helical micro / nanofiber nonwoven material as described in any one of claims 1 to 4, characterized in that, Used as a filter material.

6. The application according to claim 5, characterized in that, The filter material has a filtration efficiency of 82.3%-85.6% for PM 0.3μm NaCl particles in the air, and a filtration resistance of 74-76.4Pa.

Images