Nozzle of a electrospinning machine

Abstract

The present invention provides a nozzle for an electrospinning apparatus that minimizes clogging of the raw material solution and enables the stable and simultaneous production of multiple fibers. [Solution] A metal nozzle (30) connected to a raw material injection machine of an electrospinning apparatus that injects raw material liquid toward a target electrode for spinning, comprising a cylindrical first base (31) and a second base (32) mounted inside the first base (31), the raw material liquid is delivered along a cylindrical flow path formed by the first base (31) and the second base (32), and the raw material liquid is injected as multiple jets at the tip of the second base (32). The tip of the second base (32) is provided with continuous irregularities along the circumferential direction.

Description

【Technical Field】 【0001】 The present invention relates to a nozzle for injecting a raw material liquid of an electrospinning apparatus. 【Background Art】 【0002】 An electrospinning apparatus is known as one of the spinning means, and when injecting a raw material liquid toward a target electrode connected to the ground, a high voltage is applied to the nozzle of the injector injecting the raw material liquid. The raw material liquid ejected from the nozzle to which the high voltage is applied becomes charged and forms into a filament by the action of an electric field formed between the nozzle and the target electrode, and is deposited as nanofibers on the target electrode. A polymer solution, a molten polymer, or the like is used as the raw material liquid. 【0003】 In such an electrospinning apparatus, although nanofibers can be produced, the production amount per unit time decreases due to the refinement of the fiber diameter, and the production cost per certain amount increases. 【0004】 Therefore, it has been proposed to improve the production efficiency by making the nozzles of the injector multi-connected. For example, it has been proposed to arrange a plurality of nozzles while interposing a gas ejection nozzle for ejecting gas between the nozzles (see, for example, Patent Document 1). Alternatively, it has been proposed to provide a plurality of nozzles in a spinneret to which the raw material liquid is supplied to form a nozzle row (see, for example, Patent Document 2). 【Prior Art Documents】 【Patent Documents】 【0005】 【Patent Document 1】 Japanese Patent No. 5383937 【Patent Document 2】 Japanese Unexamined Patent Application Publication No. 2012-26043 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0006】 However, when multiple nozzles are used in a connected configuration, there is a problem in that the electric field generated by the high voltage applied to the nozzle is prone to fluctuations due to the influence of charged raw material liquid injected from other nozzles. In particular, fluctuations in the electric field cause variations in the injection state of the raw material liquid from the nozzles, making it difficult to manufacture nanofibers of a consistent thickness. In some cases, this can cause clogging of the nozzles, necessitating the interruption of manufacturing and reducing manufacturing efficiency. 【0007】 In light of the current situation, the inventors conducted research and development to create a nozzle that is less susceptible to the surrounding electric field, thereby enabling the stable simultaneous production of multiple nanofibers, and have arrived at the present invention. 【0008】 In other words, the nozzle of the electrospinning apparatus of the present invention has a structure that is less susceptible to influence on the electric field, thereby providing a nozzle for an electrospinning apparatus that minimizes clogging of the raw material liquid in the nozzle and enables the stable simultaneous production of multiple fibers. [Means for solving the problem] 【0009】 The nozzle of the electrospinning apparatus of the present invention is a metal nozzle connected to a raw material injection machine of an electrospinning apparatus that injects raw material liquid toward a target electrode for spinning, and comprises a cylindrical first base and a second base mounted inside the first base, and supplies the raw material liquid along a cylindrical flow path formed by the first base and the second base, and injects the raw material liquid as multiple jets at the tip of the second base. 【0010】 Furthermore, the nozzle of the electrospinning apparatus of the present invention also has the following features. (1) The tip of the second base body is provided with continuous irregularities along the circumferential direction. (2) The protruding part of the uneven surface is in the shape of an inverted V. (3) The tip of the second base is composed of a cylindrical wall that gradually becomes thinner towards the tip. [Effects of the Invention] 【0011】 According to the present invention, a nozzle for an electrospinning apparatus is provided that consists of a first substrate and a second substrate, and the raw material liquid is supplied along a cylindrical channel formed by the first substrate and the second substrate, while the raw material liquid is ejected as multiple jets from the tip of the second substrate. This suppresses clogging of the raw material liquid and enables the stable and simultaneous production of multiple fibers. [Brief explanation of the drawing] 【0012】 [Figure 1] This is a schematic diagram illustrating the electrospinning apparatus according to this embodiment. [Figure 2] This is a schematic diagram of the nozzle's longitudinal cross-section. [Figure 3] (a) Front view of the second substrate. (b) Bottom view of the second substrate. [Modes for carrying out the invention] 【0013】 As schematically shown in Figure 1, the electrospinning apparatus comprises a target electrode 10 made of a metal plate, an injection machine 20 connected to a nozzle 30 that injects the raw material liquid toward the target electrode 10, and a high-voltage power supply 40 that applies a high voltage to the nozzle 30 of the injection machine 20. An earth wire 11 is connected to the target electrode 10 to bring it to ground potential. 【0014】 The injection machine 20 is a supply means for supplying the raw material liquid, and is usually a syringe 22 equipped with a piston 21. The piston 21 is propelled forward at a constant speed by a pushing device 23, which allows a constant amount of the raw material liquid in the syringe 22 to be injected. The injection machine 20 is not limited to a configuration consisting of a piston 21 and a syringe 22, but can take any form as long as it can stably supply the raw material liquid. 【0015】 The raw material liquid may be a polymer solution, a molten polymer, or the like generally used in an electrospinning apparatus. In the present embodiment, a polyurethane solution having a predetermined concentration will be described. 【0016】 A feed pipe 24 is communicatively connected to the tip of a syringe 22 that constitutes an injector 20, and the raw material liquid is fed to a nozzle 30 through this feed pipe 24, and the raw material liquid is ejected as a jet J having a thin diameter from the tip of the nozzle 30. In particular, the nozzle 30 is capable of ejecting the raw material liquid as a plurality of jets J. 【0017】 The nozzle 30 ejects the raw material liquid toward a target electrode 10 provided at a predetermined distance apart. The nozzle 30 is mounted on an appropriate support base 50 and faces the target electrode 10. 【0018】 The nozzle 30 is connected to a high-voltage power supply device 40 through a power supply wiring 41, and the nozzle 30 is set to a predetermined high potential. By setting the target electrode 10 to a ground potential, a desired electric field is formed between the nozzle 30 and the target electrode 10. 【0019】 Hereinafter, the configuration of the nozzle 30, which is the main part of the present invention, will be described. FIG. 2 shows a schematic longitudinal sectional view of the nozzle 30. 【0020】 The nozzle 30 is composed of a cylindrical first base 31 and a second base 32 mounted inside the first base 31. Further, in the nozzle 30 of the present embodiment, the second base 32 can be detachably mounted on the first base 31, and a connecting base 33 for communicatively connecting with the feed pipe 24 is provided. The first base 31 and the second base 32 are made of metal and have a potential applied by a high-voltage power supply device 40 through a power supply wiring 41. Also, the connecting base 33 is made of metal in the present embodiment. 【0021】 The cylindrical first base body 31 is configured to be able to insert the second base body 32 from the tip side inward, and is provided with a first cylindrical portion 31a, a second cylindrical portion 31b, a third cylindrical portion 31c, a fourth cylindrical portion 31d, and a fifth cylindrical portion 31e having different inner diameter dimensions from the tip side toward the base end side. The second cylindrical portion 31b has a smaller diameter than the first cylindrical portion 31a, the third cylindrical portion 31c has a smaller diameter than the second cylindrical portion 31b, and the fourth cylindrical portion 31d has a smaller diameter than the third cylindrical portion 31c. The fifth cylindrical portion 31e has a larger diameter than the fourth cylindrical portion 31d. Further, the tip side of the first base body 31 is tapered and has a reduced diameter. 【0022】 On the end face on the base end side of the first base body 31, a screw hole (not shown) for mounting to the support base body 50 is provided, and it can be mounted to the support base body 50 by a screw (not shown). 【0023】 The second base body 32 is a cylindrical body that can be inserted into the portions of the first cylindrical portion 31a, the second cylindrical portion 31b, and the third cylindrical portion 31c of the first base body 31. In particular, the second base body 32 has a tip portion 32a that is loosely fitted into the portion of the first cylindrical portion 31a of the first base body 31, an intermediate portion 32b that is loosely fitted into the portion of the second cylindrical portion 31b of the first base body 31, and a base end portion 32c that is fitted into the portion of the third cylindrical portion 31c of the first base body 31. 【0024】 The intermediate portion 32b of the second base body 32 that is loosely fitted into the second cylindrical portion 31b of the first base body 31 forms a cylindrical gap 34 between the second cylindrical portion 31b and the intermediate portion 32b, and this gap 34 is used as a feed flow path for the raw material liquid. Further, this gap 34 is in a state of being communicated with the cylindrical gap 34 generated between the first cylindrical portion 31a of the first base body 31 and the tip portion 32a by loosely fitting the tip portion 32a of the second base body 32 into the first cylindrical portion 31a of the first base body 31, and is used as a cylindrical feed flow path for the raw material liquid. In FIG. 2, for the sake of convenience of explanation, the gap 34 is drawn large, but actually, the interval is about 0.07 to 0.7 mm. Also, the gap 34 between the second cylindrical portion 31b and the intermediate portion 32b is provided over the entire length direction of the intermediate portion 32b, but it may be provided only in the portion on the downstream side of a through-flow path 35 (described later) provided in the intermediate portion 32b. 【0025】 The cylindrical second base 32 is provided with a central channel 36a that runs along the central axis through the base end 32c and the intermediate section 32b, making it tubular. In this embodiment, this central channel 36a is long enough to reach the tip end 32a. The raw material liquid is supplied to this central channel 36a via the connecting base 33, which will be described later. 【0026】 Furthermore, as shown in Figures 2 and 3(a), the second base body 32 is provided with multiple through-channels 35 that extend radially through the cylindrical shape of the second base body 32 in the middle of the intermediate section 32b. These through-channels 35 are channels for supplying the raw material liquid, which has been supplied to the central channel 36a provided in the second base body 32, into the gap 34 between the second cylindrical section 31b of the first base body 31 and the intermediate section 32b of the second base body 32. 【0027】 The tip portion 32a of the second base 32 is provided with a cylindrical wall 37, which is formed by recessing the center of the tip. In particular, the cylindrical wall 37 gradually thins towards the tip. 【0028】 Furthermore, as shown in Figure 3(b), the tip of the cylindrical wall 37 has an uneven shape with convex portions 38a and concave portions 38b arranged alternately along the circumferential direction. In this way, the tip side of the second base body 32 is composed of the cylindrical wall 37, and the tip of this cylindrical wall 37 has an uneven shape that continues along the circumferential direction, which makes it easier to cause so-called current concentration at the convex portions 38a of the uneven shape. This creates areas with higher current and areas with lower current at predetermined intervals within the second base body 32, which is voltageened to a high voltage by the high-voltage power supply device 40. 【0029】 Here, the high-current portion is the convex portion 38a of the uneven shape, and the low-current portion is the concave portion 38b of the uneven shape. In order to enhance the current concentration effect in the high-current portion, the convex portion 38a is made in the shape of an inverted V, and current concentration is created at the apex of the inverted V. The raw material liquid receives charge supply from the high-current portion, which locally generates a so-called Taylor cone and forms a jet J. 【0030】 Furthermore, by gradually thinning the cylindrical wall 37 towards the tip, it is made easier to concentrate current at the protrusion 38a. 【0031】 It should be noted that jets J are not formed at all of the protrusions 38a at the tip of the cylindrical wall 37, but rather multiple jets J are generated depending on the diameter of the cylindrical wall 37, the voltage applied to the second base body 32, the amount of raw material liquid supplied, the spacing between the protrusions 38a, etc. 【0032】 The base end 32c side of the central channel 36 provided on the second base body 32 is provided with a female thread 39a that is screwed into the connecting base body 33. 【0033】 The connecting base 33 is a pipe having a supply channel 36b along its central axis, and is a cylindrical body that can be inserted into the fourth cylindrical portion 31d and the fifth cylindrical portion 31e of the first base 31. That is, the connecting base 33 has a small diameter portion 33a that fits into the fourth cylindrical portion 31d of the first base 31, and a large diameter portion 33b that fits into the fifth cylindrical portion 31e of the first base 31. 【0034】 The tip of the narrow-diameter portion 33a of the connecting base 33 is provided with a male screw 39b that engages with the female screw 39a provided on the second base 32. 【0035】 The second base 32 is fixedly attached to the first base 31 by screwing together the female thread 39a provided on the second base 32 and the male thread 39b provided on the connecting base 33, and the raw material liquid can be supplied to the nozzle 30 by connecting the supply pipe 24 to the base end of the connecting base 33. 【0036】 The raw material liquid supplied to the connecting base 33 via the supply pipe 24 passes through the supply channel 36b of the connecting base 33 and reaches the central channel 36a of the second base 32. The raw material liquid that reaches the central channel 36a passes through the through channel 35 of the second base 32 and reaches the channel configured as the gap 34 between the second cylindrical section 31b and the intermediate section 32b. Furthermore, it reaches the channel configured as the gap 34 between the first cylindrical section 31a and the tip section 32a, and the raw material liquid is ejected from the tip of the nozzle 30 as a thin, thread-like jet J. 【0037】 The raw material liquid, which is supplied in a cylindrical shape to the gap 34 between the first cylindrical portion 31a and the tip portion 32a, becomes a thin, thread-like jet J due to the voltage applied to the nozzle 30 and the tip shape of the second base 32 of the nozzle 30. 【0038】 In this embodiment, as shown in Figure 2, the position of the tip of the first base 31 of the nozzle 30 and the position of the tip of the second base 32 are made substantially the same. However, the position of the tip of the second base 32 may be made to protrude more than the position of the tip of the first base 31. 【0039】 Thus, in the nozzle of the electrospinning apparatus of the present invention, the jet J is formed by the action of an electric field, rather than by using a conventional tapered nozzle. This prevents clogging of the raw material liquid and allows for the stable generation of the jet J. 【0040】 Furthermore, since each jet J is generated in a stable state as a result of electrical interaction with other jets J, fluctuations can be suppressed, and multiple nanofibers with stable fiber diameters can be manufactured simultaneously. [Explanation of symbols] 【0041】 10 Target electrodes 11. Ground wire 20 injection machine 21 pistons 22 syringes 23 Pushing device 30 nozzles 31 First Substrate 31a 1st cylinder part 31b Second cylinder part 31c 3rd cylinder part 31d 4th cylinder part 31e 5th cylinder part 32 Second Substrate 32a Tip 32b middle part 32c proximal end 33 Connection base 33a Narrow diameter part 33b Large diameter part 34 gaps 35 Through-flow channel 36a Central channel 36b Feed channel 37 Cylindrical wall 38a Convex part 38b Recess 39a Female thread 39b male thread 40 High-voltage power supply 50 Support base

Claims

[Claim 1] In a metal nozzle connected to the injection machine of a electrospinning apparatus that injects a raw material liquid toward a target electrode for spinning, It comprises a cylindrical first base and a second base that is mounted inside the first base. A nozzle for an electrospinning apparatus, which supplies the raw material liquid along a cylindrical channel formed by the first substrate and the second substrate, and ejects the raw material liquid as multiple jets at the tip of the second substrate. [Claim 2] The nozzle of the electrospinning apparatus according to claim 1, wherein the tip of the second substrate is provided with continuous irregularities along the circumferential direction. [Claim 3] The nozzle of the electrospinning apparatus according to claim 2, wherein the protruding portion of the aforementioned irregularities is in the shape of an inverted V. [Claim 4] The nozzle of the electrospinning apparatus according to claim 2 or claim 3, wherein the tip side of the second base body is composed of a cylindrical wall that gradually becomes thinner towards the tip.

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