A device and method for preparing melt-differentiated electrostatically spun nanofiber hollow yarn

Abstract

The application discloses a kind of melt differential electrostatic spinning nanofiber hollow core yarn preparation device and method, device includes spray head, airflow twisting tube, high-voltage static generator, electrode plate, electrode plate support, core yarn cylinder, pay-off roller, collection roller, collection line cylinder and water pool, preparation method is to spray head into plastic melt, melt enters from melt inlet, after uniform distribution on conical surface and groove, water-soluble core yarn is passed through core yarn fixing hole, then passes through airflow twisting tube, is pulled out above airflow twisting tube, is wound on collection line cylinder, starts take-up motor and pay-off motor, so that the line speed of collection line cylinder and core yarn cylinder is identical, melt forms multiple jet under electrostatic field and is wrapped on core yarn, the obtained core-spun yarn is placed in water pool for 3-10 min, the core yarn is dissolved in water, and the remaining part is taken out to dry to obtain nanofiber hollow core yarn. The grooves on the conical surface of the spray head fix the number of jets, improve the continuous stability of the jets, and are beneficial to the improvement of the quality of the hollow core yarn.

Description

Technical Field

[0001] This invention relates to an apparatus and method for preparing melt differential electrospun nanofiber hollow yarn, belonging to the field of electrospinning. Background Technology

[0002] Nanofiber products possess high specific surface area, high porosity, unique interfacial characteristics, and excellent physicochemical properties, making them a key area for the development of high-performance fibers. Currently, solution / melt electrospinning is the most commonly used nanofiber preparation technology due to its relatively simple equipment, operation, low energy consumption, and wide applicability of raw materials. However, the complex and rapid whipping of the jet during electrospinning often results in the electrospun fibers piling up into disordered fiber membranes, leading to problems such as simple structure and poor mechanical properties. Hollow yarn is produced by winding fibers into a water-soluble core yarn, then removing the core yarn to obtain a pure fiber-supported hollow structure. Its unique hollow structure can trap air and amplify capillary effects. Constructing nanofibers into hollow yarn structures allows the yarn to combine the excellent properties of nanofibers with the characteristics of a hollow structure, showing great application potential in fields such as artificial blood vessels, nerve conduits, electromagnetic shielding fabrics, and capillary irrigation. Currently, hollow yarns are mainly constructed using fibers with diameters ranging from a few micrometers to tens of micrometers, such as cotton, polyester, and nylon, or using nanofibers prepared by solution electrospinning. For example, patent CN116770480A describes hollow yarns constructed using cotton fibers, and patent CN219137045U describes hollow yarns constructed using solution electrospun fibers. However, the traditional fiber fineness in these methods is insufficient, and for solution electrospun nanofibers, the preparation process involves organic solvent pollution, low yield, and weak fiber strength. Furthermore, for commonly used polyolefin polymers and polyester polymers, it is difficult to find suitable solvents for solution electrospinning technology. Melt electrospinning technology, on the other hand, has advantages such as a green and environmentally friendly preparation process, complete conversion of raw materials into fibers, and high fiber density and strength, making it highly suitable for processing polyolefin polymers and polyesters into nanofibers. Therefore, constructing hollow yarns using melt electrospun nanofibers is an important approach for the development of hollow nanofiber yarns. Summary of the Invention

[0003] The purpose of this invention is to solve the problems existing in the prior art and to provide a device and method for preparing melt differential electrospun nanofiber hollow yarn.

[0004] To achieve the above objectives, the technical solution adopted by this invention is as follows: A melt differential electrospun nanofiber hollow yarn preparation device, comprising a nozzle, an airflow twisting tube, a high-voltage electrostatic generator, an electrode plate, an electrode plate support, a core yarn spool, a pay-off roller, a collecting roller, a collecting spool, and a water tank. The nozzle is grounded, and the electrode plate is located 5-15 cm below it. Below the electrode plate is the electrode plate support. The electrode plate has a central hole with a diameter of 3-5 cm, into which the airflow twisting tube is placed. Both the airflow twisting tube and the electrode plate are fixed by the electrode plate support. The electrode plate is connected to the high-voltage electrostatic generator. Below the electrode plate support is the pay-off roller, which is more than 20 cm away from the lower end of the electrode plate support. The core yarn spool is fixed on the pay-off roller, and a water-soluble core yarn, such as vinylon, is wound on the spool. A take-up roller is placed on the side of the electrode plate support, with a distance of more than 20 cm between the take-up roller and the electrode plate support. The collecting spool is fixed on the take-up roller. The water tank is placed separately.

[0005] The nozzle of this invention, a melt differential electrospinning nanofiber hollow yarn preparation device, is made of stainless steel, copper, or aluminum. The nozzle consists of a central shaft and an outer sleeve. A melt inlet is located at the top of the outer sleeve, and the lower end of the outer sleeve is a conical surface. Multiple shallow grooves are evenly distributed circumferentially on the conical surface. The groove width is 0.5-1 mm, the groove length is 3-5 mm, the groove thickness is 0.1-0.4 mm, and the groove spacing is 1-3 mm. These grooves direct and divide the melt flow on the conical surface, forcing differential flow and fixing the number of multiple jets.

[0006] This invention discloses a melt differential electrospun nanofiber hollow yarn preparation device, wherein the airflow twisting tube is made of a non-conductive material with poor polarization properties. The airflow twisting tube consists of an upper end cap and a main body tube. The gap between the upper end cap and the main body tube forms a high-pressure chamber and a tangential hole. A core yarn fixing hole with a diameter of 1-3 mm is located at the lower end of the main body tube. The core yarn fixing hole ensures that the strong helical motion of the core yarn occurs only inside the airflow twisting tube. Due to the high-speed rotation of the core yarn within the airflow twisting tube, the core yarn is positioned at the center or off-center within the yarn body, thus ensuring that the hollow channels of the hollow yarn are also positioned at the center or off-center within the yarn body.

[0007] This invention discloses a melt differential electrospun nanofiber hollow yarn preparation device, wherein the diameter of the water-soluble core yarn is in the range of 0.1-3 mm. Hollow yarns with different pore sizes can be prepared by using core yarns of different diameters.

[0008] This invention discloses a melt differential electrospinning device for preparing hollow nanofiber yarns. The ratio of the nanofiber layer thickness to the core yarn diameter must be greater than 1, and the nanofiber layer thickness must be greater than 1 mm to ensure sufficient self-supporting strength and reduce the collapse of the hollow structure. The thickness of the nanofiber layer can be controlled by adjusting the melt supply rate and the rotational speed of the collecting roller.

[0009] This invention discloses a method for preparing nanofiber hollow yarn using melt differential electrospinning: A plasticized melt is introduced into a nozzle, entering through the melt inlet and evenly distributed on the conical surface and groove. A water-soluble core yarn is then passed through a core yarn fixing hole and then through an airflow twisting tube. The yarn is pulled out from above the airflow twisting tube and wound onto a collecting spool. The take-up and pay-off motors are activated to ensure the collecting spool and the core yarn spool have the same linear velocity. A high-voltage electrostatic generator is turned on, and compressed air is introduced into the airflow twisting tube. Under the electrostatic field, the melt forms multiple jets. The negative pressure generated by the airflow draws these jets into the airflow twisting tube and wraps them around the core yarn, forming nanofiber core-spun yarn. The collecting spool filled with core-spun yarn is placed in a water tank for 3-10 minutes. After the core yarn dissolves in the water, the collecting spool is removed and dried to obtain nanofiber hollow yarn.

[0010] The advantages of this invention's melt differential electrospinning nanofiber hollow yarn preparation device and method are as follows: 1. This method does not involve organic solvents during preparation, and compared with existing nanofiber hollow yarn preparation methods, it has the advantages of being green, environmentally friendly, pollution-free, and producing dense and strong fibers. 2. This method is suitable for processing thermoplastic polymers such as polyolefins, polyesters, and polylactic acid. 3. The grooves on the nozzle cone surface of the device fix the number of jets, improving the continuous stability of the jets and thus contributing to the improvement of hollow yarn quality. 4. The aperture of the hollow yarn prepared by this method is adjustable. 5. This method can increase the fiber layer thickness of the hollow yarn by increasing the melt supply rate and reducing the roller speed. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a melt differential electrospinning nanofiber hollow yarn preparation device according to the present invention.

[0012] Figure 2 This is a schematic diagram of the nozzle structure of a melt differential electrospinning nanofiber hollow yarn preparation device according to the present invention.

[0013] Figure 3 This is a schematic diagram of the airflow twisting tube structure of the melt differential electrospinning nanofiber hollow yarn preparation device of the present invention.

[0014] Figure 4 This is a schematic diagram of the nozzle generating multiple jets in a melt differential electrospinning nanofiber hollow yarn preparation device of the present invention.

[0015] Figure 5 This is a schematic diagram of the airflow twisting process used in the preparation device for melt differential electrospun nanofiber hollow yarn of the present invention to form core-spun yarn.

[0016] In the diagram: 1—Nozzle; 2—Airflow twisting tube; 3—High-voltage electrostatic generator; 4—Electrode plate; 5—Electrode plate support; 6—Core yarn; 7—Core yarn spool; 8—Pay-off roller; 9—Nanofiber; 10—Core-spun yarn; 11—Collection roller; 12—Collection spool; 13—Water tank; 14—Nanofiber hollow yarn; 15—Outer tube; 16—Melte inlet; 17—Central shaft; 18—Conical surface; 19—Groove; 20—Upper end cap; 21—Tangential hole; 22—High-pressure chamber; 23—Airflow inlet; 24—Main tube; 25—Core yarn fixing hole; 26—Melte. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0018] This invention discloses a melt differential electrospun nanofiber hollow yarn preparation device, such as... Figure 1 As shown, it includes a nozzle 1, an airflow twisting tube 2, a high-voltage electrostatic generator 3, an electrode plate 4, an electrode plate support 5, a core yarn spool 7, a pay-off roller 8, a collecting roller 11, a collecting spool 12, and a water tank 13. The nozzle 1 consists of a central shaft 17 and an outer sleeve 15, as shown... Figure 2 As shown, there is a melt inlet 16 above the outer sleeve 15, and a conical surface 18 at the lower end of the outer sleeve 15. Multiple shallow grooves 19 are evenly distributed circumferentially on the conical surface 18. The grooves 19 are 0.5-1mm wide, 3-5mm long, and 0.1-0.4mm thick, with a spacing of 1-3mm. The nozzle 1 is grounded, and an electrode plate 4 is located 5-15cm below it. Below the electrode plate 4 is an electrode plate support 5. The electrode plate 4 has a central hole with a diameter of 3-5cm, into which an airflow twisting tube 2 is placed. Both the airflow twisting tube 2 and the electrode plate 4 are fixed by the electrode plate support 5. The airflow twisting tube 2 consists of an upper end cap 20 and a main tube 24, as shown... Figure 3 As shown. The gap between the upper cover 20 and the main tube 24 forms a high-pressure chamber 22 and a tangential hole 21. There is a core yarn fixing hole 25 at the lower end of the main tube 24, with a diameter of 1-3 mm. The electrode plate 4 is connected to the high-voltage electrostatic generator 3. Below the electrode plate support 5 is a pay-off roller 8, with a distance greater than 20 cm between the pay-off roller 8 and the lower end of the electrode plate support 5. A core yarn bobbin 7 is fixed on the pay-off roller 8, and a water-soluble core yarn 6, such as vinylon, is wound on the bobbin 7. A take-up roller 11 is placed on the side of the electrode plate support 5, with a distance greater than 20 cm between the take-up roller 11 and the electrode plate support 5. A collection bobbin 12 is fixed on the take-up roller 11. The water tank 13 is placed separately.

[0019] Example 1:

[0020] This invention discloses a melt differential electrospun nanofiber hollow yarn preparation device, with the same structure as above, but with the following specific parameters: the width of groove 19 is 1 mm, the length of groove 19 is 5 mm, the thickness of groove 19 is 0.4 mm, and the spacing between grooves 19 is 2 mm. The distance between nozzle 1 and electrode plate 4 is 10 cm.

[0021] A method for preparing melt differential electrospun nanofiber hollow yarn, using the above-mentioned apparatus, and the preparation process is as follows:

[0022] like Figure 1 , 4 As shown in Figure 5, melt 26 (the melt is polypropylene, manufactured by Natureworks, grade 1500) is injected from melt inlet 16 at a rate of 0.2 g / min. Melt 26 spreads on the conical surface 18 and is divided by multiple grooves 19. The material is plasticized into melt 26 and injected into melt inlet 16 via extrusion or via injection through a plunger after plasticization in an extruder. Water-soluble core yarn 6 is passed through core yarn fixing hole 25 (water-soluble core yarn 6 is 1 mm diameter stranded vinylon, manufactured by Zhejiang Tianfeng Plastic Machinery Co., Ltd., grade 402), pulled out from above the airflow twisting tube 2, and wound onto the collecting spool 12. The linear speed of take-up roller 11 and give-up roller 8 is the same, at 20 m / min. The high-voltage electrostatic generator 3 is turned on, applying a 50 kV high-voltage electrostatic charge to electrode plate 4, and nozzle 1 generates dozens of nanofibers. Compressed air is injected into the airflow inlet 23 at a pressure of 0.3 MPa. The compressed air passes through the high-pressure chamber 22 and the oblique hole 21 to form multiple tangential airflows, creating a cyclone within the airflow twisting tube 2. The negative pressure created by the cyclone draws the nanofibers 9 into the airflow twisting tube 2 and forms core-spun yarn 10. The collection spool 12, filled with core-spun yarn 10, is placed in a water tank 13 for 3 minutes, then removed and dried to obtain nanofiber hollow yarn 14.

[0023] Example 2:

[0024] This invention discloses a melt differential electrospun nanofiber hollow yarn preparation device, with the same structure as above, but with the following specific parameters: the width of groove 19 is 0.5 mm, the length of groove 19 is 3 mm, the thickness of groove 19 is 0.4 mm, and the spacing between grooves 19 is 1 mm. The distance between nozzle 1 and electrode plate 4 is 10 cm.

[0025] This invention discloses a method for preparing melt differential electrospun nanofiber hollow yarn, using the aforementioned apparatus, and the preparation process is as follows: Figure 1 , 4As shown in Figure 5, melt 26 (polylactic acid, manufactured by Natureworks, grade 3251D) is injected into melt inlet 16 at a rate of 0.5 g / min. Melt 26 spreads on conical surface 18 and is divided by multiple grooves 19. Core yarn 6 is passed through core yarn fixing hole 25 (core yarn 6 is 2 mm diameter plied vinylon, manufactured by Zhejiang Tianfeng Plastic Machinery Co., Ltd., grade 402), pulled out from above airflow twisting tube 2, and wound onto collecting spool 12. The linear velocity of take-up roller 11 and pay-off roller 8 is the same, at 10 m / min. High-voltage electrostatic generator 3 is turned on to apply 50 kV high-voltage electrostatic to electrode plate 4, generating dozens of nanofibers at nozzle 1. Compressed air is injected into airflow inlet 23 at a pressure of 0.3 MPa. Compressed air passes through the high-pressure chamber 22 and the oblique hole 21 to form multiple tangential airflows, creating a cyclone within the airflow twisting tube 2. The negative pressure generated by the cyclone draws the multiple jets into the airflow twisting tube 2 and forms core-spun yarn 10. The collecting spool 12, filled with core-spun yarn 10, is placed in a water tank for 10 minutes to obtain nanofiber hollow yarn 14.

Claims

1. A device for preparing melt-differentiated electrospun nanofiber hollow yarns, characterized by: The device comprises a nozzle, an air flow twisting tube, a high-voltage static generator, an electrode plate, an electrode plate support, a core yarn bobbin, a pay-off roller, a take-up roller, a take-up bobbin and a water tank. The nozzle is composed of a central shaft and a sleeve pipe. The sleeve pipe is provided with a melt inlet at the top and a tapered surface at the bottom. A plurality of shallow grooves are formed on the tapered surface. The nozzle is grounded. The electrode plate is 5-15 cm below the nozzle. The electrode plate support is below the electrode plate. The electrode plate is hollow and provided with a hole with a diameter of 3-5 cm. The air flow twisting tube is placed in the hole. The electrode plate and the air flow twisting tube are fixed by the electrode plate support. The electrode plate is connected to the high-voltage static generator. The pay-off roller is below the electrode plate support. The distance between the pay-off roller and the electrode plate support is greater than 20 cm. The core yarn bobbin is fixed on the pay-off roller. The water-soluble core yarn is wound on the bobbin. The take-up roller is placed on the side of the electrode plate support. The distance between the take-up roller and the electrode plate support is greater than 20 cm. The take-up bobbin is fixed on the take-up roller. The water tank is separately placed. The air flow twisting tube is made of a poor conductive material with poor polarization performance. The air flow twisting tube is composed of an upper end cover and a main tube. The gap between the upper end cover and the main tube forms a high-pressure chamber and a tangential hole. The main tube is provided with a core yarn fixing hole at the lower end with a diameter of 1-3 mm. The core yarn fixing hole enables the strong spiral movement of the core yarn to occur only inside the air flow twisting tube.

2. The device for preparing melt-differentiated electrospun nanofiber hollow yarn according to claim 1, characterized in that: The nozzle is made of stainless steel, copper or aluminum.

3. The device for preparing melt-differentiated electrospun nanofiber hollow yarn according to claim 1, characterized in that: The water-soluble core yarn is made of vinylon with a diameter of 0.1-3 mm.

4. The device for preparing melt-differentiated electrospun nanofiber hollow yarn according to claim 3, characterized in that: The water-soluble core yarn is coated with functional particles on the surface by soaking or electrostatic spraying process. The functional particles include chitosan, copper ions or carbon paste to add a functional inner layer to the hollow core yarn.

5. A method for preparing melt differential electrospun nanofiber hollow yarn, characterized in that: The device is used to prepare a melt differential electrospinning nanofiber hollow core yarn. First, the plastic melt is introduced into the nozzle. The melt enters from the melt inlet and is uniformly distributed on the tapered surface and the grooves. Then, the water-soluble core yarn is inserted through the core yarn fixing hole and the air flow twisting tube. The air flow twisting tube is pulled out above the air flow twisting tube and wound on the take-up bobbin. The take-up motor and the pay-off motor are started to make the linear speed of the take-up bobbin and the core yarn bobbin the same. The high-voltage static generator is turned on and compressed air is introduced into the air flow twisting tube. The melt forms multiple jets under the electrostatic field. The negative pressure formed by the air flow pulls the multiple jets into the air flow twisting tube and wraps them around the core yarn to form a nanofiber core-spun yarn. The take-up bobbin wrapped with the core-spun yarn is placed in the water tank for 3-10 minutes. The core yarn dissolves in water. The remaining part of the nanofiber core-spun yarn is taken out and dried to obtain a nanofiber hollow core yarn.

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