A method and apparatus for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn

Abstract

This invention relates to a piezoelectric nanofiber yarn, specifically to a method and apparatus for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn. The method involves polarizing the PVDF electrospun nanofiber / ITO composite film in a high-voltage electric field to improve the piezoelectric properties of PVDF. The composite film is then irradiated with a laser beam and cut into 5mm wide strips. These strips are passed through guide grooves and a pair of roller jaws. A guide wheel introduces a conductive filament, which is then twisted with the PVDF electrospun nanofiber / ITO composite film strip to form the piezoelectric nanofiber yarn. This piezoelectric nanofiber yarn can generate a 3mV output voltage when stretched and retracted under a force of 2cN. This allows the yarn to be woven into smart clothing as a sensor for health monitoring. It features high flexibility, good breathability, good washability, and durability, making it suitable for widespread application.

Description

Technical Field

[0001] This invention relates to a method for preparing piezoelectric nanofiber yarn, specifically to a method and apparatus for preparing a composite yarn of conductive filament / electrospun nanofiber / ITO film. Background Technology

[0002] Piezoelectric sensors, capable of generating electrical charge upon deformation, have wide applications in health monitoring and energy harvesting. For example, when placed on or near the human body, piezoelectric sensors can record vital signs, including heart rate, blood pressure, and chest expansion during respiration. Integrating such sensors into clothing allows for continuous wireless health monitoring. Piezoelectric sensors can also be used for structural health monitoring, i.e., monitoring vibration and shock by integrating them into building components or vehicles. Polymer-based piezoelectric sensors typically utilize polyvinylidene fluoride (PVDF) or one of its copolymers. To enable PVDF to exhibit a piezoelectric effect, polar β-phase microcrystals must be formed; this is typically achieved by stretching the polymer at temperatures below its crystalline melting point or by polarizing the material under very high electric fields. Until recently, research on PVDF in fibrous form focused primarily on nanofiber films with diameters in the nanometer range, produced through electrospinning. Piezoelectric composite films are fabricated by metallizing both sides of the piezoelectric nanofiber film and further embedding it in epoxy resin for mechanical shielding.

[0003] The published invention patent CN112899806A dissolves PVDF or its polymer in DMF and Ac, heats and stirs for a certain time; adds an appropriate amount of fluorescent complex and additives to dissolve, and obtains an electrospinning precursor solution; after electrospinning, a multifunctional piezoelectric nanofiber material is obtained.

[0004] The published invention patent CN109989179A involves adding polyvinylidene fluoride (PVDF) to a solvent containing sucrose and stirring with a magnetic stirrer until completely dissolved. The PVDF / sucrose solution is then spun using an electrospinning device, and the fibers are collected using aluminum electrodes to obtain a PVDF / sucrose piezoelectric nanofiber membrane. However, laminating the membrane onto textiles makes production relatively complex, and the membrane can negatively impact the performance of the final textile product (e.g., drape, comfort, and breathability).

[0005] This invention discloses a method and apparatus for preparing piezoelectric nanofiber yarn, which can produce 12pC N using a simple manufacturing process at low cost. -1 The piezoelectric nanofiber yarn has high output power, and the smart textiles woven from this yarn have good flexibility and breathability. Summary of the Invention

[0006] In view of this, the present invention provides a method and apparatus for preparing a composite yarn of conductive filament / electrospun nanofiber / ITO film.

[0007] To achieve the above-mentioned technical objectives, the present invention discloses an apparatus for preparing conductive filament / PVDF electrospun nanofiber / ITO film composite yarn, comprising: a film winding roller, and antistatic rubber roller pair one, antistatic rubber roller pair two, antistatic rubber roller pair three and antistatic rubber roller pair four arranged sequentially on one side of the film winding roller;

[0008] An insulating plate and a conductive metal plate are provided between the first antistatic rubber roller and the second antistatic rubber roller; conductive metal needles are evenly distributed on the insulating plate, and the conductive metal needles are connected to a high voltage generator.

[0009] A laser cutting nozzle is provided between the second antistatic rubber roller and the third antistatic rubber roller;

[0010] A guide groove is provided between the third antistatic rubber roller and the fourth antistatic rubber roller; a yarn cylinder and a conductive wire positioning wheel are provided at the top of the guide groove;

[0011] The yarn guide hook and twisting winding device are located on one side of the antistatic rubber roller pair.

[0012] Optionally, the surface linear velocity of the first antistatic roller is the same as that of the film winding roller; the surface linear velocity of the second antistatic roller is 1.02-1.16 times that of the first antistatic roller to ensure the flatness of the PVDF electrospun nanofiber / ITO composite film during the polarization process; the surface linear velocity of the third antistatic roller is 1.02-1.16 times that of the second antistatic roller to ensure the flatness of the PVDF electrospun nanofiber / ITO composite film during the laser cutting process; and the surface linear velocity of the fourth antistatic roller is 1.02-1.16 times that of the third antistatic roller to ensure the flatness of the PVDF electrospun nanofiber / ITO composite film strip when it is laminated with conductive filaments.

[0013] Optionally, the conductive wire positioning wheel is provided with a groove for fixing the conductive wire.

[0014] Optionally, the central axis of the guide groove along its length is located in the same vertical plane as the center of the conductive wire positioning wheel.

[0015] Optionally, the twisting and winding device includes a twisting hook, a twisting disc, a bobbin, and a spindle; wherein,

[0016] The twisting hook is vertically fixed on the twisting disc with its tip facing outwards, and the tube is inserted into the spindle.

[0017] This invention also claims protection for a method for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn. The method for preparing the conductive filament / electrospun nanofiber / ITO film composite yarn using the above-mentioned apparatus specifically includes the following steps:

[0018] 1) The film winding roller unwinds the PVDF electrospun nanofiber / ITO composite film at a speed of 5-20 m / min, and feeds it into the antistatic rubber roller at the same surface linear speed as the film winding roller;

[0019] 2) Control the surface linear speed of the antistatic rubber roller and turn on the high voltage generator to output a positive high voltage of 5000-60000V to the conductive metal needle. A high voltage electric field is formed between the conductive metal needle and the conductive metal plate. The corona discharge of the conductive metal needle polarizes the PVDF electrospun nanofiber membrane, so that the electric dipoles in the PVDF electrospun nanofiber membrane are oriented and aligned.

[0020] It should be noted that the orientation is arranged from top to bottom to improve the piezoelectric properties of the PVDF electrospun nanofiber membrane.

[0021] 3) Control the surface linear speed of the antistatic roller to cut the PVDF electrospun nanofiber / ITO composite film into PVDF electrospun nanofiber / ITO composite film strips with a width of 3-10 mm through the laser cutting nozzle;

[0022] 4) The yarn bobbin actively unwinds, feeding the conductive wire onto the actively rotating conductive wire positioning wheel, and controlling the surface linear speed of the conductive wire positioning wheel to be the same as the surface linear speed of the antistatic rubber roller pair 4; and the conductive wire positioning wheel fixes the position of the conductive wire and feeds it to the jaws of the antistatic rubber roller pair 4, so that the conductive wire merges with the PVDF electrospun nanofiber / ITO composite film strip, and the guide groove ensures that the conductive wire is in the middle part of the PVDF electrospun nanofiber / ITO composite film strip;

[0023] 5) The conductive filament is wrapped around the center of the PVDF electrospun nanofiber / ITO composite film strip, and is twisted by the subsequent twisting and winding device and the twist on the yarn strip to form a twisting triangle area and make a conductive filament / electrospun nanofiber / ITO film composite yarn.

[0024] The conductive filament / electrospun nanofiber / ITO film composite yarn passes through the guide hook and is wound onto the bobbin after passing around the twisting hook. The twisting hook is driven by the twisting disc to rotate at a speed of 2500-10000 rpm. The bobbin is driven by the spindle to rotate at a speed of 2526-2604 rpm, which ultimately causes the twisting hook to add 100-800 twists / meter to the conductive filament / electrospun nanofiber / ITO film composite yarn. The spindle drives the bobbin to reciprocate in the horizontal direction at a speed of 0.02-0.9 m / min so that the yarn is evenly wound along the length of the bobbin.

[0025] Optionally, the PVDF electrospun nanofiber / ITO composite membrane is composed of a PVDF electrospun nanofiber membrane and an ITO composite membrane; and the PVDF electrospun nanofiber membrane is located on one side of the insulating plate.

[0026] Optionally, the surface linear velocity of the antistatic rubber roller to the second surface is 1.02-1.16 times that of the antistatic rubber roller to the first surface, the surface linear velocity of the antistatic rubber roller to the third surface is 1.02-1.16 times that of the antistatic rubber roller to the second surface, and the surface linear velocity of the antistatic rubber roller to the fourth surface is 1.02-1.16 times that of the antistatic rubber roller to the third surface.

[0027] Optionally, the conductive filament on the core of the conductive filament / electrospun nanofiber / ITO film composite yarn serves as one electrode; the ITO composite film conductive layer of the PVDF electrospun nanofiber / ITO composite film serves as another electrode.

[0028] Furthermore, in the conductive filament / electrospun nanofiber / ITO film composite yarn, after the PVDF electrospun nanofiber membrane is twisted, the electric dipoles are arranged outward from the yarn core along the radial direction of the yarn.

[0029] As can be seen from the above technical solutions, compared with the prior art, the method and apparatus for preparing conductive filament / electrospun nanofiber / ITO film composite yarn provided by the present invention have the following superior effects:

[0030] 1) The method disclosed in this invention can prepare piezoelectric nanofiber yarns at low cost. The conductive layer of the core electrode conductive filament and the conductive layer of the skin electrode ITO (indium tin oxide) composite film will not short-circuit. Moreover, the conductive layer of the skin electrode ITO (indium tin oxide) composite film has a large contact area with the outer layer of the PVDF electrospun nanofiber film, resulting in high charge collection efficiency.

[0031] 2) The PVDF electrospun nanofiber membrane is polarized, and after the PVDF electrospun nanofiber membrane is twisted in the conductive yarn / PVDF electrospun nanofiber / ITO membrane composite yarn, the electric dipoles are arranged outward from the yarn core along the radial direction of the yarn, thereby improving the charge generation efficiency of the PVDF electrospun nanofiber membrane in the conductive yarn / PVDF electrospun nanofiber / ITO membrane composite yarn.

[0032] 3) The side of the ITO (Indium Tin Oxide) composite film away from its conductive layer has the functions of insulation and wear resistance. On the one hand, it prevents the charge generated by the PVDF electrospun nanofiber film from neutralizing itself, and on the other hand, it improves the service life of the conductive filament / PVDF electrospun nanofiber / ITO film composite yarn.

[0033] 4) When the conductive filament / PVDF electrospun nanofiber / ITO membrane composite yarn is subjected to cyclic stretching and shrinkage, it can generate an output voltage of 3mV, thereby enabling the piezoelectric nanofiber yarn to be woven into smart clothing as a sensor for health monitoring; and the fabric woven from the conductive filament / PVDF electrospun nanofiber / ITO membrane composite yarn has high flexibility and breathability. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of an apparatus for preparing a composite yarn of conductive filament / PVDF electrospun nanofiber / ITO film.

[0036] Figure 2 This is a schematic diagram of the structure of a PVDF electrospun nanofiber / ITO composite membrane.

[0037] Figure 3 This is a schematic diagram of the structure of a composite yarn of conductive filament / PVDF electrospun nanofiber / ITO film.

[0038] Figure 4 This is a schematic diagram of a twisting and winding device. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention discloses a method and apparatus for preparing a composite yarn of conductive filament / electrospun nanofiber / ITO film.

[0041] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

[0042] The technical solution of the present invention will now be further described in conjunction with the accompanying drawings.

[0043] As attached Figure 1 As shown, the film winding roller 1 unwinds the PVDF (polyvinylidene fluoride) electrospun nanofiber / ITO (indium tin oxide) composite film 2 at a speed of 5-20 m / min, and feeds in an antistatic rubber roller (3 and 4). The surface linear velocity of the antistatic rubber roller (3 and 4) is the same as that of the film winding roller 1.

[0044] The surface linear velocity of the antistatic rollers (9 and 10) is 1.02 to 1.16 times that of the antistatic rollers (3 and 4) to ensure the flatness of the PVDF electrospun nanofiber / ITO composite film 2 during the polarization process. Conductive metal needles 7 are uniformly distributed on the insulating plate 6. The high-voltage generator 5 outputs a positive high voltage of 5000 to 60000V to the conductive metal needles 7, forming a high-voltage electric field between the conductive metal needles 7 and the conductive metal plate 8. The corona discharge of the conductive metal needles 7 polarizes the PVDF electrospun nanofiber film 201, causing the electric dipoles in the PVDF electrospun nanofiber film 201 to align from top to bottom, thereby improving the piezoelectric properties of the PVDF electrospun nanofiber film 201.

[0045] The surface linear velocity of the antistatic rollers (13 and 14) is 1.02 to 1.16 times that of the antistatic rollers (9 and 10) to ensure the flatness of the PVDF electrospun nanofiber / ITO composite film 2 during the laser cutting process. The laser cutting nozzle 11 cuts the PVDF electrospun nanofiber / ITO composite film 2 into PVDF electrospun nanofiber / ITO composite film strips 12 with a width of 3 to 10 mm.

[0046] The yarn bobbin 16 actively unwinds, feeding the conductive filament 17 onto the actively rotating conductive filament positioning wheel 18. The surface linear velocity of the yarn bobbin 16 and the conductive filament positioning wheel 18 is the same as the surface linear velocity of the antistatic rubber rollers (19 and 20). The conductive filament positioning wheel 18 has grooves that fix the position of the conductive filament 17 and feed it to the jaws of the antistatic rubber rollers (19 and 20) where it merges with the PVDF electrospun nanofiber / ITO composite film strip 12.

[0047] The surface linear velocity of the antistatic rollers (19 and 20) is 1.02 to 1.16 times that of the antistatic rollers (13 and 14) to ensure the flatness of the PVDF electrospun nanofiber / ITO composite film strip 12 when it is combined with the conductive filament 17. The central axis of the guide groove 15 along its length is located in the same vertical plane as the center of the conductive filament positioning wheel 18. The PVDF electrospun nanofiber / ITO composite film strip 12 passes through the guide groove 15 to ensure that the conductive filament 17 is in the middle of the PVDF electrospun nanofiber / ITO composite film strip 12.

[0048] As attached Figure 4 As shown, the conductive filament 17 is wrapped around the center of the PVDF electrospun nanofiber / ITO composite film strip 12, and is twisted by the subsequent twisting and winding device 24 and the twist on the yarn is transmitted to form a twisting triangle area 21 and make a conductive filament / electrospun nanofiber / ITO film composite yarn 22.

[0049] The conductive filament / electrospun nanofiber / ITO film composite yarn 22 passes through the yarn guide hook 23, wraps around the twisting hook 241, and is wound onto the bobbin 243; the twisting hook 241 is driven to rotate by the twisting disc 242, and the bobbin 243 is driven to rotate by the spindle 244, so that the twisting hook 241 adds twist to the conductive filament / electrospun nanofiber / ITO film composite yarn 22.

[0050] As attached Figure 2 As shown, the upper part of the PVDF electrospun nanofiber / ITO composite membrane 2 is a PVDF electrospun nanofiber membrane 201; the lower part of the PVDF electrospun nanofiber / ITO composite membrane 2 is an ITO (indium tin oxide) composite membrane 202, and the conductive layer of the ITO (indium tin oxide) composite membrane 202 is close to the PVDF electrospun nanofiber membrane 201.

[0051] As attached Figure 3 As shown, a conductive filament 17 serves as an electrode on the core of the conductive filament / PVDF electrospun nanofiber / ITO film composite yarn 22; the outer layer has a PVDF electrospun nanofiber / ITO composite film 2, in which the conductive layer of the ITO (indium tin oxide) composite film 202 serves as another electrode.

[0052] Furthermore, in the conductive filament / PVDF electrospun nanofiber / ITO membrane composite yarn 22, after the PVDF electrospun nanofiber membrane 201 is twisted, the electric dipoles are arranged outward from the yarn core along the radial direction of the yarn.

[0053] A 5cm conductive filament / PVDF electrospun nanofiber / ITO film composite yarn was tested on an Instron universal testing machine at a speed of 1.0mm / min. -1 The crosshead speed is used to cyclically stretch and retract the yarn under a force of 0-2cN. The open-circuit voltage of the yarn is recorded simultaneously using a Keithley digital millivolt recorder, generating an output voltage of 3mV.

[0054] When the conductive filament / PVDF electrospun nanofiber / ITO film composite yarn 22 is stretched or bent and deformed, opposite charges are generated on the two surfaces of the PVDF electrospun nanofiber film 201. These charges are collected and output by the conductive filament 17 and the conductive layer of the ITO (indium tin oxide) composite film 202, respectively, thus converting the yarn deformation into an electrical signal.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn, characterized in that, The preparation apparatus used includes: a film roll (1), and antistatic rubber roller pair one, antistatic rubber roller pair two, antistatic rubber roller pair three and antistatic rubber roller pair four arranged sequentially on one side of the film roll (1); An insulating plate (6) and a conductive metal plate (8) are provided between the first antistatic rubber roller and the second antistatic rubber roller; conductive metal needles (7) are evenly distributed on the insulating plate (6), and the conductive metal needles (7) are connected to a high voltage generator (5); A laser cutting nozzle (11) is provided between the second antistatic rubber roller and the third antistatic rubber roller; A guide groove (15) is provided between the third antistatic rubber roller and the fourth antistatic rubber roller; a yarn cylinder (16) and a conductive wire positioning wheel (18) are provided at the top of the guide groove (15); The yarn guide hook (23) and twisting winding device (24) are located on one side of the antistatic rubber roller pair; The method for preparing conductive filament / electrospun nanofiber / ITO film composite yarn using the aforementioned preparation device specifically includes the following steps: 1) The film winding roller (1) unwinds the PVDF electrospun nanofiber / ITO composite film (2) at a speed of 5 to 20 m / min, and feeds it into the antistatic rubber roller pair at the same surface linear speed as the film winding roller (1); 2) Control the surface linear speed of the antistatic rubber roller and turn on the high voltage generator (5) to output a positive high voltage of 5000~60000V to the conductive metal needle (7). A high voltage electric field is formed between the conductive metal needle (7) and the conductive metal plate (8). The corona discharge of the conductive metal needle (7) polarizes the PVDF electrospun nanofiber membrane, so that the electric dipoles in the PVDF electrospun nanofiber membrane are oriented and arranged. 3) Control the surface linear speed of the antistatic rubber roller to cut the PVDF electrospun nanofiber / ITO composite film (2) into PVDF electrospun nanofiber / ITO composite film strips (12) with a width of 3-10 mm through the laser cutting nozzle (11); 4) The yarn bobbin (16) actively unwinds, conveying the conductive wire (17) to the actively rotating conductive wire positioning wheel (18), and controlling the surface linear speed of the conductive wire positioning wheel (18) to be the same as the surface linear speed of the antistatic rubber roller pair; and the conductive wire positioning wheel (18) fixes the position of the conductive wire (17) and conveys it to the jaw of the antistatic rubber roller pair, so that the conductive wire (17) merges with the PVDF electrospun nanofiber / ITO composite film strip (12), and the guide groove (15) ensures that the conductive wire (17) is in the middle part of the PVDF electrospun nanofiber / ITO composite film strip (12); 5) The conductive filament (17) is wrapped in the center of the PVDF electrospun nanofiber / ITO composite film strip (12), and is twisted by the subsequent twisting and winding device (24) and the twist on the yarn is transmitted to form a twisting triangle area (21) and made into conductive filament / electrospun nanofiber / ITO film composite yarn (22). The conductive filament / electrospun nanofiber / ITO film composite yarn (22) passes through the yarn guide hook (23) and is wound onto the bobbin (243) after passing around the twisting hook (241). The twisting hook (241) is driven by the twisting disc (242) to rotate at a speed of 2500 to 10000 rpm. The bobbin (243) is driven by the spindle (244) to rotate at a speed of 2526 to 2604 rpm, so that the twisting hook (241) adds 100 to 800 twists per meter to the conductive filament / electrospun nanofiber / ITO film composite yarn (22). The spindle (244) drives the bobbin (243) to reciprocate in the horizontal direction at a speed of 0.02 to 0.9 m / min so that the yarn is evenly wound onto the length direction of the bobbin.

2. The method for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn according to claim 1, characterized in that, The conductive wire positioning wheel (18) is provided with a groove for fixing the conductive wire (17).

3. The method for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn according to claim 1, characterized in that, The central axis of the guide groove (15) along its length is located in the same vertical plane as the center of the conductive wire positioning wheel (18).

4. The method for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn according to claim 1, characterized in that, The twisting and winding device (24) includes a twisting hook (241), a twisting disc (242), a bobbin (243), and a spindle (244); wherein, The twisting hook (241) is vertically fixed on the twisting disc (242) with the hook tip facing outward, and the tube (243) is inserted into the spindle (244).

5. The method for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn according to claim 1, characterized in that, The PVDF electrospun nanofiber / ITO composite membrane (2) is composed of a PVDF electrospun nanofiber membrane (201) and an ITO composite membrane (202); and the PVDF electrospun nanofiber membrane (201) is located on one side of the insulating plate (6).

6. The method for preparing a conductive filament / electrospun nanofiber / ITO film composite yarn according to claim 1, characterized in that, The conductive filament on the core of the conductive filament / electrospun nanofiber / ITO film composite yarn (22) serves as one electrode; the ITO composite film conductive layer of the PVDF electrospun nanofiber / ITO composite film serves as another electrode. Furthermore, in the conductive filament / electrospun nanofiber / ITO film composite yarn, after the PVDF electrospun nanofiber membrane is twisted, the electric dipoles are arranged outward from the yarn core along the radial direction of the yarn.

Images