JP7568493B2 - Spinning apparatus, fiber sheet manufacturing apparatus and manufacturing method, fiber manufacturing method - Google Patents

Description

The present invention relates to a spinning device, a fiber sheet manufacturing device and manufacturing method, and a fiber manufacturing method.

Spinning is a technique in which a raw material liquid consisting of a viscous body made by heating and melting a spinning material such as a resin or dissolving it in a solvent to make it fluid is continuously supplied to a specified storage section such as a spinning head and discharged from a spinneret connected to the storage section to produce threads. Depending on the form of the raw material liquid, there are melt spinning and solution spinning. In addition, depending on the form in which the raw material liquid is fixed into the shape of a thread after being discharged from the spinneret, there are known spinning methods such as wet spinning, dry spinning, melt blown, and electrospinning (electrostatic spinning).

Melt-blowing and electrospinning methods are used to manufacture nanofibers, which are extremely fine fibers with nano-sized fiber diameters. For example, when nonwoven fabrics are made of such ultrafine fibers, various properties such as flexibility, liquid retention, concealment, wipeability, separability, and insulation are improved, so nonwoven fabrics made of ultrafine fibers are in demand.

In a spinning device or nonwoven fabric manufacturing device using electrospinning, a technique is known in which a nonwoven fabric made of ultrafine fibers is manufactured by discharging the raw material liquid from a plurality of spinnerets arranged in a single or multiple rows in order to improve production efficiency, etc. (see Patent Documents 1 to 3). For example, the nonwoven fabric manufacturing device described in Patent Document 1 includes a storage section for the raw material liquid, a liquid delivery pump, and a support supply member that supports a plurality of nozzles having spinnerets at their tips and distributes the raw material liquid to each of the plurality of nozzles, and is configured to send the raw material liquid from the storage section toward the support supply member by the liquid delivery pump, and distribute the raw material liquid to each of the nozzles within the support supply member. The devices described in Patent Documents 2 and 3 are also generally configured in this manner.

JP 2008-303503 A JP 2011-89240 A JP 2019-60040 A

Figure 9 shows the schematic configuration of a spinning device 90, which is an example of a conventional spinning device as described in Patent Documents 1 to 3. The spinning device 90 has a metering pump 91 and a plurality of spinning devices 93 equipped with a nozzle having a spinneret 94 at the tip, arranged on one side, a pair of liquid delivery blocks 92, 92 that have the function of distributing the raw material liquid delivered from the metering pump 91 to each spinning device 93, and an outlet side flow path 96 for the raw material liquid that connects these parts. The metering pump 91 is connected to a storage section 10 that stores the raw material liquid via an inlet side flow path 95, and the raw material liquid in the storage section 10 flows through the inlet side flow path 95 and is delivered to the metering pump 91 by driving the metering pump 91. The storage section 10 is connected to a melt extruder 11 that supplies molten resin as the raw material liquid.

In the spinning device 90, the metering pump 91 and each liquid feed block 92 are connected by a single outlet side flow path 96, which branches into multiple outlet side flow paths 96 within the liquid feed block 92 and is connected one-to-one to multiple spinnerets 94. Therefore, in the spinning device 90, the raw material liquid used by the multiple spinning devices 93 is sent out collectively from the metering pump 91 by the single outlet side flow path 96, and distributed to each spinning device 93 by the multiple outlet side flow paths 96 that branch off during the sending process.

In the spinning device 90 configured as described above, the amount of resin discharged from the multiple spinnerets 94 may be unintentionally uneven. If the amount of resin discharged from the multiple spinnerets is uneven, the fiber sheet made of fibers spun from the discharged resin may have basis weight unevenness in which parts with a relatively large amount of fiber and parts with a relatively small amount of fiber are mixed, and this may cause variations in the performance of products using the fiber sheet. Such basis weight unevenness is particularly noticeable when producing thin sheets such as nanofiber sheets, so in such cases even greater precision is likely to be required for the amount of resin discharged.

The objective of the present invention is to provide a technology that can uniformly eject resin from multiple spinnerets for spinning, and efficiently produce a high-quality fiber sheet with no unevenness in basis weight.

The present invention is a spinning device that includes a plurality of spinnerets that discharge a raw material liquid containing a resin, a metering pump that delivers the raw material liquid to the spinnerets via an outlet-side flow path, and a metering discharge section that connects the metering pump to the outlet-side flow path, and the spinning device includes a plurality of metering discharge sections, a 1:1 correspondence between the metering discharge sections and the spinnerets, and a plurality of metering spinning structures that include a single 1:1 corresponding spinneret and single metering discharge section, and the outlet-side flow path that connects both, and the metering device includes a plurality of metering spinning structures that have independent outlet-side flow paths for each of the plurality of metering spinning structures.

The present invention also relates to a fiber sheet manufacturing apparatus that includes the spinning device of the present invention. The present invention also relates to a fiber sheet manufacturing method that uses the manufacturing device of the present invention.

The present invention also provides a fiber manufacturing method that includes a distribution process for distributing a raw material liquid containing a resin to a plurality of mutually independent outlet-side flow paths, a liquid delivery process for quantitatively delivering the raw material liquid distributed to the plurality of outlet-side flow paths to a plurality of spinnerets that correspond one-to-one to the plurality of outlet-side flow paths using a pump, and a spinning process for discharging the raw material liquid from the plurality of spinnerets to form fibers, in which the difference between the discharge weight of the resin per unit time from each of the plurality of spinnerets and their arithmetic mean values is within 10% of the arithmetic mean value.

The present invention provides a technology that allows for the resin to be uniformly discharged from multiple spinnerets for spinning, and allows for the efficient production of high-quality fiber sheets with no unevenness in basis weight.

FIG. 1 is a schematic perspective view of a main part of one embodiment of a spinning device of the present invention. FIG. 2 is a schematic diagram of the spinning apparatus shown in FIG. 1 as viewed from the direction indicated by the symbol X in FIG. 1, and includes a schematic enlarged plan view of a part of the spinning apparatus (a constant quantity discharge portion forming member). FIG. 3 is a schematic exploded perspective view of a liquid feed block in the spinning apparatus shown in FIG. FIG. 4 is a schematic diagram (side view) of the spinning apparatus shown in FIG. 1 as viewed from the direction indicated by the symbol Y in FIG. FIG. 5 is a schematic front view of the liquid feed block in the spinning apparatus shown in FIG. 1, illustrating the position of the metering pump. FIG. 6 is a schematic diagram of a spinning apparatus according to another embodiment of the present invention. FIG. 7 is a graph showing the amount of fiber spun (weight of resin discharged) per unit time from each of a plurality of spinnerets in the spinning apparatus of the embodiment. FIG. 8 is a graph showing the amount of fiber spun (weight of resin discharged) per unit time from each of a plurality of spinnerets in a spinning device of a comparative example. FIG. 9 is a schematic diagram of a conventional spinning device.

The present invention will now be described based on preferred embodiments thereof with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are essentially schematic, and the ratios of the dimensions may differ from the actual ones.

Figures 1 to 5 show a spinning device 1, which is one embodiment of the spinning device of the present invention. The spinning device 1 is equipped with a plurality of spinnerets 51 that discharge a raw material liquid containing a resin, a metering pump 2 that delivers the raw material liquid to the spinnerets 51 via an outlet side flow path 42, and a metering discharge unit 3 that connects the metering pump 2 to the outlet side flow path 42.

In this embodiment, the spinning device 1 includes a single metering pump 2, a metering discharge section forming member 30 having a metering discharge section 3, a liquid feed block 4 having an inlet side flow path 41 and an outlet side flow path 42 therein, and a plurality of (16 in the illustrated embodiment) spinning devices 5 having a spinneret 51. The raw material liquid supplied from the outside to the metering pump 2 via the inlet side flow path 41 is fed to each spinning device 5 via the metering discharge section 3 and the outlet side flow path 42, and discharged from each spinneret 51 to produce fibers. In FIG. 2, for ease of understanding, the inlet side flow path 41 is indicated by a solid arrow, and the outlet side flow path is indicated by a hollow arrow.

The raw material liquid may be a solution containing a resin (resin-containing solution) or a resin melt, and can be selected appropriately depending on the spinning method, etc. The resin-containing solution is prepared by dissolving or dispersing various resins that are the raw material for the fibers in a solvent. The resin melt is prepared by heating various resins (thermoplastic resins) that are the raw material for the fibers to above their melting points.

The resin contained in the raw material liquid can be any resin that can be used for spinning, without any particular restrictions. Examples of thermoplastic resins used in the resin melt include polyolefin-based thermoplastic resins such as polypropylene, polyethylene, and ethylene-propylene copolymer, polyester-based thermoplastic resins such as polyethylene terephthalate, polybutylene terephthalate, and polylactic acid, and polyamide-based thermoplastic resins such as nylon. These can be used alone or in combination of two or more.

In this embodiment, a resin melt is used as the raw material liquid, and when the spinning device 1 is in use, it is connected to a melt extruder 11 via a pipe 12 as shown in FIG. 2. The melt extruder 11 is configured to melt chips of raw material resin and supply the melted raw material liquid to a predetermined destination (spinning device 1), and is equipped with an inlet for the raw material resin, a cylinder with a built-in screw, and the like. Any known melt extruder can be used as the melt extruder 11 without any particular restrictions.

The metering pump 2 may be any pump capable of repeatedly delivering a fixed amount of raw material liquid, and any known pump may be used without any particular restrictions. In this embodiment, the metering pump 2 is a gear pump, and includes a motor 21 connected to a control device (not shown), and a pump section 22 having a gear connected to the output shaft of the motor 21 and configured to be rotatable. The primary side of the pump section 22 is connected to the melt extruder 11, which is the source of the raw material liquid, via the inlet flow path 41, and the secondary side of the pump section 22 is connected to the spinneret 51 of each spinning device 5 via the outlet flow path 42. When the motor 21 is driven by a control device (not shown), the gear of the pump section 22 rotates to pump the raw material liquid on the primary side to the secondary side.

2, the constant-quantity discharge section 3 is a through hole that penetrates the plate-shaped constant-quantity discharge section forming member 30 in the thickness direction, and the constant-quantity pump 2 and the outlet side flow path 42 are connected via the constant-quantity discharge section 3. The constant-quantity discharge section forming member 30 has the same number of constant-quantity discharge sections 3 (16 in the illustrated embodiment) as the number of spinnerets 51 (spinning devices 5) scattered therein. The constant-quantity discharge section forming member 30 is interposed between the constant-quantity pump 2 and the liquid feed block 4 (first block 43 described later). The constant-quantity discharge section forming member 30 is made of a material (metal, plastic, etc.) that is resistant to the raw material liquid. In the illustrated embodiment, the constant-quantity discharge section forming member 30 has a circular shape in a plan view, but the plan view shape of the constant-quantity discharge section forming member 30 is not particularly limited.

The liquid feed block 4 supports each part of the spinning apparatus 1, such as the metering pump 2, the metering discharge unit 3, and the spinning device 5. Flow paths 41, 42 for the raw material liquid are formed inside the liquid feed block 4, and the liquid feed block 4 is made of a material (metal, plastic, etc.) that is resistant to the raw material liquid. In this embodiment, the liquid feed block 4 has a rectangular parallelepiped shape as shown in FIG. 3, but the shape of the liquid feed block 4 is not particularly limited.

In this embodiment, the liquid supply block 4 is configured to be divisible into multiple parts. Specifically, as shown in FIG. 3, the liquid supply block 4 is configured to be divisible into two parts in the thickness direction, and includes a first block 43 in which the metering pump 2 is disposed, and a second block 44 in which the spinning device 5 is disposed. The two blocks 43, 44 can be attached and detached to each other by fasteners such as bolts and nuts or other known integration means.

In this embodiment, the outlet side flow path 42 includes a portion formed at the boundary between the first block 43 and the second block 44, as shown in FIG. 2 and FIG. 3. More specifically, the liquid feed block 4 has the same number of outlet side flow paths 42 (16 in the illustrated embodiment) as the number of spinnerets 51 (spinning devices 5), and the portion extending in a direction perpendicular to the thickness direction (discharge direction of the raw material liquid) of the liquid feed block 4 in each of the plurality of outlet side flow paths 42 consists of a portion formed on the opposing surface of the first block 43 with the second block 44 and a portion formed on the opposing surface of the second block 44 with the first block 43, and the two blocks 43, 44 are overlapped at appropriate positions to form the outlet side flow path 42. The plurality of outlet side flow paths 42 formed at the boundary between the two blocks 43, 44 and extending in a direction perpendicular to the discharge direction of the raw material liquid extend radially from the arrangement position of the metering pump 2 (the center when the liquid feed block 4 is viewed from the discharge direction of the raw material liquid) as shown in FIG. 3.

In this embodiment, multiple spinning devices 5 each having a spinneret 51 are arranged on one side of the liquid feed block 4 (the side opposite to the side on which the metering pump 2 is arranged). Because the spinning apparatus 1 is thus equipped with multiple spinnerets 51, it is possible to efficiently produce fiber sheets such as nonwoven fabrics made of spun fibers.

The arrangement pattern of the multiple spinning devices 5 (spinning ports 51) is not particularly limited. In this embodiment, multiple spinning device rows (two rows in the illustrated embodiment) in which multiple (eight in the illustrated embodiment) spinning devices 5 are arranged at predetermined intervals in one direction are provided on one side of the liquid feed block 4 at predetermined intervals in a direction perpendicular to the extension direction of the spinning device rows. In this embodiment, the multiple spinning devices 5 are arranged in a staggered pattern. The term "staggered pattern" used here refers to an arrangement in which the spinning devices 5 are offset (preferably half a pitch) between adjacent spinning device rows.

Each of the multiple spinning devices 5 is equipped with a nozzle having a spinneret 51 at its tip. The nozzle is a hollow member made of a conductive material such as metal, and is connected to the metering pump 2 via the constant-volume discharge section 3 and the outlet-side flow path 42, so that the raw material liquid delivered from the metering pump 2 can be discharged from the spinneret 51.

In this embodiment, each of the multiple spinning devices 5 has an outlet (not shown) near the spinneret 51 for injecting a gas flow such as hot air, and while the gas flow is being ejected from the outlet, the raw material liquid can be ejected from the spinneret 51 to perform spinning, and each spinning device 5 is equipped with a gas flow generator 6. By bringing the raw material liquid ejected from the spinneret 51 into contact with the gas flow and spinning it, the fiber is made finer, making it even easier to manufacture ultrafine fibers such as nanofibers. As the gas flow generator 6, any known device capable of generating hot air or the like can be used without any particular restrictions.

As described above, as shown in FIG. 2, the spinning device 1 has a plurality of constant-quantity discharge sections 3 (16 in the illustrated embodiment), and the plurality of constant-quantity discharge sections 3 correspond one-to-one to a plurality of (16 in the illustrated embodiment) spinnerets 51, and the spinning device 1 has a plurality of constant-quantity spinning structures 20 including a single spinneret 51 and a single constant-quantity discharge section 3 that correspond one-to-one, and an outlet-side flow path 42 that connects the two. In other words, the constant-quantity spinning structure 20 is composed of a single spinneret 51, a single constant-quantity discharge section 3, and an outlet-side flow path 42 that connects the two, and the spinning device 1 has the same number of constant-quantity spinning structures 20 as the number of spinnerets 51 (16 in the illustrated embodiment).

One of the main features of the spinning device 1 is that the outlet flow paths 42 of the multiple fixed-volume spinning structures 20 are independent of each other. That is, in each of the multiple fixed-volume spinning structures 20, the outlet flow path 42 of the quantitative spinning structure 20 does not merge with or branch off from the outlet flow paths 42 of the other quantitative spinning structures 20, and extends from the single fixed-volume discharge section 3 of the quantitative spinning structure 20 to the single spinneret 51 of the quantitative spinning structure 20. That is, in the spinning device 1, each of the multiple spinnerets 51 (spinning devices 5) is provided with its own outlet flow path 42, and the raw material liquid is sent from the metering pump 2 to each spinneret 51 via its own outlet flow path 42.

The characteristic configuration of the spinning device 1 is in contrast to the spinning device 90 shown in FIG. 9, in which a single outlet side flow passage 96 extending from a metering pump 91 to a spinneret 94 branches off along the way to form multiple outlet side flow passages 96. With this characteristic configuration, which differs from the conventional technology, the spinning device 1 is able to uniformly eject resin from multiple spinnerets, which was difficult to achieve with conventional technology such as the spinning device 90, and can efficiently produce high-quality fiber sheets (nonwoven fabrics) with no basis weight unevenness.

In this embodiment, the multiple fixed-volume spinning structures 20 are connected to each other via a single liquid feed block 4, and the outlet side flow paths 42 of each of the multiple fixed-volume spinning structures 20 are arranged within this single liquid feed block 4. This configuration makes it possible to assemble and install components related to the delivery of the raw material liquid (liquid feed related components) such as the heater, filter, pressure sensor, and safety valve described below in a single member (liquid feed block 4), simplifying the configuration of the spinning device 1 and making it possible to achieve the best results with a relatively small component configuration.

In this embodiment, the liquid feed block 4 has a heating function capable of heating the outlet side flow path 42 of each of the multiple fixed-volume spinning structures 20. Specifically, as shown in FIG. 4, a heater insertion port 7 into which a heater (not shown), which is a type of heating means, can be inserted, is provided on the side of the liquid feed block 4 (the surface intersecting both the arrangement surface of the metering pump 2 and the arrangement surface of the spinning device 5). A plurality of heater insertion ports 7 are provided in each of the first block 43 and the second block 44 constituting the liquid feed block 4, and the plurality of heater insertion ports 7 are intermittently arranged in the short direction of the liquid feed block 4 having a rectangular shape in a plan view. Each heater insertion port 7 extends over approximately the entire length of the liquid feed block 4 having a rectangular shape in a plan view in the longitudinal direction (the direction in which the spinning device row extends), and the heater inserted into the heater insertion port 7 also extends over approximately the entire length of the liquid feed block 4 in the longitudinal direction. By inserting a heater into the heater insertion port 7, it is possible to heat the raw material liquid flowing through the outlet side flow path 42 in the liquid feed block 4 with the heater. As the heater, a known heater can be used without any particular restrictions. In this embodiment, the liquid feed block 4 is configured to allow for the intermittent placement of a heating means such as a heater, thereby allowing the outlet flow path 42 of each of the multiple fixed-volume spinning structures 20 to be heated. Heating the raw material liquid in the outlet flow path 42 makes it easier to control the amount of resin discharged from the spinneret 51, and makes it possible to discharge the resin uniformly from the multiple spinnerets 51 with high precision.

In this embodiment, the liquid delivery block 4 includes one or more liquid delivery-related components selected from 1) a filter (not shown) for filtering the raw material liquid, 2) a pressure sensor 9 for measuring the pressure in the outlet side flow path 42, and 3) a safety valve for adjusting the pressure in the outlet side flow path 42, and the liquid delivery-related components are adapted to correspond to each of the multiple fixed-volume spinning structures 20.

The filter can be installed, for example, in either or both of the inlet flow path 41 and the outlet flow path 42. The location of the filter in the inlet flow path 41 can be, for example, the connection to the source of the raw material liquid in the spinning device 1 (melt extruder 11 in the illustrated embodiment) or its vicinity. The location of the filter in the outlet flow path 42 is preferably arranged in the outlet flow path 42 of each of the fixed-quantity spinning structures 20 from the viewpoint of being compatible with each of the multiple fixed-quantity spinning structures 20, for example, the boundary between each of the multiple spinning devices 5 and the liquid feed block 4 or its vicinity. By installing the filter in such a location, it is possible to remove carbonized resin, impurities, etc. contained in the raw material liquid, which suppresses clogging of the spinneret 51 and makes the discharge of the raw material liquid smooth, making it easier to solve the problem of uniform discharge of resin from the multiple spinnerets 51. As the filter, any filter that can be used for filtering raw material liquid containing resin can be used without any particular restrictions, and for example, a sintered metal filter can be used.

The pressure in the outlet flow passage 42 measured by the pressure sensor is an indicator of the amount of resin, the raw material for the fibers, supplied to the spinneret 51. Therefore, by placing a pressure sensor in the liquid feed block 4, it is possible to manage the amount of resin discharged from the spinneret 51 and to detect clogging of the spinneret 51 early, making it easier to solve the problem of uniform discharge of resin from multiple spinnerets 51. Any known pressure sensor that can be used for this type of application can be used without any particular restrictions.

The safety valve is useful because it can prevent the metering pump 2 from being damaged when excessive pressure is applied. The safety valve can be configured to have, for example, a valve seat, a valve body, and a drive unit for opening and closing the valve body, and when the pressure in the outlet side flow path 42 is equal to or lower than a predetermined value, the valve body is closed, and when the pressure in the outlet side flow path 42 exceeds the predetermined value, the valve body is opened, and the raw material liquid is discharged from the outlet side flow path 42 to the outside of the spinning device 1.

The reference numeral 8 in FIG. 3 indicates the installation location of the pressure sensor and the safety valve. In the embodiment shown in FIG. 3, the spinning device 1 (liquid feed block 4) is provided with 16 outlet flow paths 42, the same number as the number of spinnerets 51. Therefore, in order to be able to accommodate each of the multiple fixed-volume spinning structures 20, the installation locations 8 of the pressure sensor and the safety valve are also 16, corresponding to each outlet flow path 42 (some not shown). The installation location of the pressure sensor and the installation location of the safety valve are the same. In the embodiment shown in FIG. 3, the pressure sensor 9 is installed in one of the 16 installation locations 8.

In this embodiment, the discharge direction of the raw material liquid from the multiple (16 in the illustrated embodiment) spinnerets 51 is the same, and as shown in FIG. 5, when the multiple spinnerets 51 (spinning devices 5) are viewed from the discharge direction, a virtual rectangle is created with a virtual straight line connecting the two spinnerets with the longest distance between them as a diagonal, and the virtual rectangle is divided into three equal parts in the longitudinal direction to form a central region, preferably in the central region M (the region shaded in FIG. 5) when the virtual rectangle is further divided into three equal parts in the lateral direction. The center of the metering pump 2 is preferably single, and the single metering pump 2 is connected to multiple (16 in the illustrated embodiment) metering discharge units 3. In order to enable uniform discharge of resin from multiple spinnerets 51, which is one of the main objectives of the present invention, it is effective to align the flow path lengths of the multiple outlet side flow paths 42 as much as possible, and this configuration makes it even easier.

Each of the multiple (16 in the illustrated embodiment) outlet flow paths 42 includes a portion (hereinafter also referred to as the "first portion") that extends in the discharge direction of the raw material liquid (thickness direction of the liquid feed block 4) and a portion (hereinafter also referred to as the "second portion") that extends in a direction perpendicular to the discharge direction, as shown in FIG. 2. Typically, the first portion is approximately the same for each outlet flow path 42 regardless of the position of the spinneret 51 (spinning device 5), but the second portion differs depending on the position of the spinneret 51 (spinning device 5) and becomes longer the farther away from the metering pump 2 (metering discharge section 3). Therefore, in order to make the flow path lengths of the multiple outlet flow paths 42 as uniform as possible, it is sufficient to make the flow path lengths of the second portions as uniform as possible. And as described above, when a single metering pump 2 connected to multiple constant-volume discharge units 3 corresponding one-to-one to multiple outlet flow paths 42 is arranged in the central region M of the virtual rectangle corresponding to the arrangement region of multiple spinnerets 51 (spinning devices 5), there is a relatively large room to adjust the flow path length of the second portion of each outlet flow path 42, making it easy to align them.

In this embodiment, the metering pump 2 (metering discharge section 3) is disposed in the central region M as described above, and as shown in FIG. 3, the second portion of each of the multiple outlet flow paths 42 extends radially from the metering pump 2 toward the outside of the spinning device 1 (liquid delivery block 4), thereby maximally aligning the flow path lengths of the outlet flow paths 42 of each of the multiple fixed-quantity spinning structures 20.

If the average value of the flow path lengths of the multiple outflow side flow paths 42 is "L _Ave " and the standard deviation is "σ", then if the flow path lengths of the multiple outflow side flow paths 42 are each within the range of "L _Ave ±3σ", it can be evaluated that the variation in the flow path lengths of the multiple outflow side flow paths 42 is small and the flow path lengths are relatively uniform. If they are within the range of "L _Ave ±2σ", it can be evaluated that the variation in the flow path lengths of the multiple outflow side flow paths 42 is even smaller and the flow path lengths are relatively more uniform. The standard deviation σ is calculated by the following (Equation 1).

"L _i " in the above (Equation 1) is the sum of the flow path lengths of the multiple outlet side flow paths 42 provided in the spinning device 1. The "flow path length of the outlet side flow path 42" here is the actual length from the constant-quantity discharge unit 3 (fixed-quantity pump 2) to the spinneret 51. For example, as described above in this embodiment, the multiple outlet side flow paths 42 each include a first portion extending in the discharge direction of the raw material liquid or in the thickness direction of the liquid feed block 4 (first block 43, second block 44) and a second portion extending in a direction perpendicular to the discharge direction, so that the length of each of these portions, specifically, the length of the portion (the first portion) extending in the thickness direction inside the first block 43, the length of the portion (the first portion) extending in the thickness direction inside the second block 44, and the length of the portion (the second portion) formed by overlapping both blocks 43 and 44, is the flow path length of the outlet side flow path 42. In the above formula 1, "n" is the total number of outlet-side flow paths 42 provided in the spinning apparatus 1, and is a natural number equal to or greater than 2. In this embodiment, n=16, and therefore the variable "i" in the above formula 1 is any one of 1 to 16. The average value L _Ave is the arithmetic average value of the flow path lengths of the multiple (16 in this embodiment) outlet-side flow paths 42 provided in the spinning apparatus 1.

Figure 6 shows the schematic configuration of spinning device 1A, which is another embodiment of the spinning device of the present invention. Regarding spinning device 1A, configurations that differ from the previously described spinning device 1 will be described, and similar configurations will be given the same reference numerals and will not be described again. For configurations of spinning device 1A that are not specifically described, the description of spinning device 1 will be applied as appropriate.

In the spinning device 1, one metering pump 2 is provided for a plurality (16 pieces) of constant-volume spinning structures 20, whereas in the spinning device 1A, the same number (four pieces) of metering pumps 2 are provided for a plurality (four pieces) of constant-volume spinning structures 20. In other words, in the spinning device 1A, a dedicated metering pump 2 is provided for each of the plurality of spinnerets 51 (spinning devices 5), and the raw material liquid is sent from the dedicated metering pump 2 to each spinneret 51 through a dedicated outlet side flow path 42. Each of the plurality of metering pumps 2 is connected to a single storage section 10 that stores the raw material liquid. The supply source of the raw material liquid, such as the storage section 10 or the melt extruder 11 connected to the spinning device 1, is not single as shown in FIG. 6, but may be the same number as the number of the constant-volume spinning structures 20 (spinnerets 51), and the plurality of supply sources may correspond one-to-one to the plurality of constant-volume spinning structures 20 (spinnerets 51). The spinning device 1A achieves the same effects as the spinning device 1.

The fiber diameter of the fiber spun in the present invention and the fiber diameter of the constituent fibers of the nonwoven fabric produced in the present invention are not particularly limited. For example, by performing spinning by a known electrospinning method using the spinning apparatus 1 described above, it is possible to spin nanofibers having a fiber diameter at or near the nano level, and it is possible to produce a fiber sheet such as a nonwoven fabric containing nanofibers.
In the present invention, the term "nanofibers" (ultrafine fibers) refers to fibers whose fiber diameter, expressed as an equivalent circle diameter, is preferably in the range of 0.1 μm or more and 7 μm or less.
The fiber diameter of various fibers such as nanofibers is measured by the following procedure: 300 fibers are randomly selected from a two-dimensional image obtained by scanning electron microscope observation, excluding defects such as fiber clumps, fiber intersections, and polymer droplets, and the transverse lengths of the fibers are measured when a line perpendicular to the longitudinal direction of the fibers is drawn, and the arithmetic average value of these values is regarded as the fiber diameter of the fibers.

The spinning device 1 can be used for various spinning methods such as melt spinning, solution spinning, wet spinning, dry spinning, melt blowing, and electrospinning (electrostatic spinning). The spinning device 1 is suitable for the melt blowing method and electrospinning method. The electrospinning method is a method of spinning by ejecting a raw material liquid containing a resin, which is a spinning material, into an electric field (electric field) generated by applying a high voltage to a conductive nozzle equipped in the spinning device and a charged electrode arranged at a distance from the nozzle, and the ejected raw material liquid is stretched into a long and thin shape in the electric field, forming a thin fiber. The electrospinning method is broadly divided into a solvent type that uses a resin-containing solution as the raw material liquid and a melt type that uses a resin melt as the raw material liquid, and the spinning device 1 can be applied to both.

One example of a fiber sheet (specifically, for example, a nonwoven fabric) manufacturing device using the meltblown method is one that includes a spinning device 1, a spinning space in which the raw material liquid discharged from each spinneret 51 of the spinning device 1 is turned into fibers, and a collection means for collecting the fibers, and the fibers are directly accumulated on the collection means to form a fiber sheet. As the collection means, any known collection means such as a net conveyor or a collection screen can be used without any particular restrictions.

An example of a method for producing a fiber sheet (specifically, for example, a nonwoven fabric) by the melt-blown method using the spinning device 1 includes a process (spinning process) in which a raw material liquid (a resin-containing solution or a resin melt) is ejected from each spinneret 51 of the spinning device 1 to form fibers, and a process in which the fibers are directly accumulated to produce a nonwoven fabric. Such a production process can be carried out using the above-mentioned fiber sheet production device by the melt-blown method.

As an example of a fiber sheet (specifically, for example, a nonwoven fabric) manufacturing apparatus using the electrospinning method, there is an apparatus that includes a spinning device 1, a spinning space in which the raw material liquid discharged from each spinneret 51 of the spinning device 1 is turned into fibers, an electric field generating means for generating an electric field in the spinning space, and a collecting means for collecting the fibers, and is configured to form a fiber sheet by directly accumulating the fibers on the collecting means. The electric field generating means includes various power sources, electrodes, etc. The electric field can be generated, for example, between the nozzle and the charged electrode by grounding the conductive nozzle having the spinneret 51 and applying a voltage to a charged electrode arranged at a distance from the nozzle using a power source. The collecting means may be grounded or have a voltage applied thereto. For example, a manufacturing apparatus having such a configuration may be that described in Japanese Patent Publication No. 2017-190552.

An example of a method for producing a fiber sheet (specifically, for example, a nonwoven fabric) by electrospinning using the spinning device 1 includes a process (electrospinning process) in which a raw material liquid is discharged from each spinneret 51 of the spinning device 1 and an electric field (electric field) is applied to the raw material liquid to form fibers, and a process in which the fibers are directly accumulated to produce a fiber sheet. This production method can be applied to both the solvent-type electrospinning method and the melt-type electrospinning method. This production method can be carried out using the above-mentioned production device for nonwoven fabric by electrospinning.

In the electrospinning method, the raw material liquid containing the resin discharged from the spinneret 51 is stretched and finely divided by the Coulomb force generated within the raw material liquid itself and preferably by the injection of the gas flow (hot air). When a resin-containing solution containing a resin and a solvent is used as the raw material liquid, the solvent instantly evaporates during stretching and the resin solidifies, forming fine fibrous material. When a resin melt is used as the raw material liquid, the resin melt is cooled and solidified while being stretched, forming fine fibrous material. The solidified fibrous material is randomly deposited on the collection means. As a result, a nonwoven fabric having fine diameter fibers and little unevenness in basis weight is formed.

The spinning apparatus 1 can be used to carry out a fiber production method (hereinafter also referred to as "fiber production method A") having the following four steps.
1) Supply step: a step of supplying a raw material liquid containing a resin to a single metering pump 2.
2) Distribution step: a step of distributing the raw material liquid to a plurality of outlet side flow paths 42 that are branched off from the metering pump 2 and are independent of each other.
3) Liquid delivery step: A step of quantitatively delivering the raw material liquid distributed to the multiple outlet side flow paths 42 to multiple spinnerets 51 that correspond one-to-one to the multiple outlet side flow paths 42.
4) Spinning process: A process of forming fibers by discharging the raw material liquid from multiple spinnerets 51.

The supply step of the fiber production method A is carried out in the spinning apparatus 1 by supplying the raw material liquid from the melt extruder 11 to the metering pump 2 via the inlet side flow path 41 .
The distribution step of fiber production method A is carried out in the spinning apparatus 1 by distributing the raw material liquid to a plurality of branched, mutually independent outlet side flow paths 42 via a plurality of constant-volume discharge sections 3 (constant-volume discharge section forming members 30) connected to a constant-volume pump 2.
According to fiber production method A having the above-described four steps, as demonstrated in the examples described later, it is possible to keep the difference between the resin discharge weight (spun amount) per unit time of each of the multiple spinnerets 51 and their arithmetic average value within 10% of the arithmetic average value, in other words, it is possible to extremely reduce the variation in the discharge amounts of the multiple spinnerets 51.

Further, the spinning apparatus 1 and the spinning apparatus 1A can each be used to carry out a fiber production method (hereinafter also referred to as "fiber production method B") having the following three steps.
1) Distribution step: a step of distributing a raw material liquid containing a resin into a plurality of outlet side flow paths 42 that are independent from each other.
2) Liquid delivery process: A process of quantitatively delivering the raw material liquid distributed to the multiple outlet side flow paths 42 to multiple spinnerets 51 that correspond one-to-one to the multiple outlet side flow paths 42 using the pump 2.
3) Spinning process: A process of forming fibers by discharging the raw material liquid from multiple spinnerets 51.

Fiber production method B is characterized in that after distributing the raw material liquid to a plurality of parts, the distributed plurality of raw material liquids are quantitatively sent to each spinneret 51. The distributing step of fiber production method B does not require quantitative distribution of the raw material liquid, but is characterized in that the raw material liquid is quantitatively sent in the liquid sending step. The spinning step of fiber production method B is the same as that of fiber production method A.
When fiber production method B is carried out using the spinning apparatus 1, in the distribution step, the raw material liquid is distributed using a single metering pump 2, and in the subsequent liquid sending step, the distributed raw material liquid is quantitatively sent to each spinneret 51 using the single metering pump 2. Also, when fiber production method B is carried out using the spinning apparatus 1A, the process is the same as when the spinning apparatus 1 is used, except that a plurality of metering pumps 2 are used.
Even with fiber production method B having the above-mentioned three steps, it is possible to keep the difference between the resin discharge weight (spun amount) per unit time from each of the multiple spinnerets 51 and their arithmetic average value within 10% of the arithmetic average value.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

Example 1
A spinning apparatus having the same configuration as the spinning apparatus 1 described above, that is, a spinning apparatus having 16 fixed-quantity spinning structures including a single spinneret and a single fixed-quantity discharge unit corresponding to each other in one-to-one correspondence, and an outlet-side flow path connecting the two, in which the outlet-side flow paths of the 16 fixed-quantity spinning structures are independent of each other, in other words, a spinning apparatus in which the outlet-side flow path extending from the metering pump to the spinneret does not branch on the way and does not merge with other outlet-side flow paths, was used to produce a nonwoven fabric consisting of an accumulation of nanofibers having a fiber diameter of 920 nm by a melt-type electrospinning method. In the spinning apparatus used, the average value L _Ave of the flow path lengths of the multiple outlet-side flow paths was 297 mm, and the standard deviation σ was 91.8 mm, satisfying the above-mentioned "L _Ave ±3σ". A resin molten liquid prepared by heating polypropylene resin to its melting point or higher was used as the raw material liquid. The conditions for carrying out the electrospinning method were a voltage of -10 kV, a distance of 300 mm between the nozzle tip (spinning nozzle) and the collection means (net conveyor), and a target spinning rate (target resin discharge weight) of 6 g/min.

Comparative Example 1
A nonwoven fabric consisting of an accumulation of nanofibers having a fiber diameter of 1,540 nm was produced by melt electrospinning in the same manner as in Example 1, except that a spinning apparatus having a configuration similar to that of the spinning apparatus 90 described above, i.e., a spinning apparatus in which the outlet side flow path extending from the metering pump to the spinneret was branched midway, was used as the spinning apparatus.

For the spinning apparatus of each Example and Comparative Example, the amount of fiber spun per unit time (weight of resin discharged) from each spinneret during the production of nonwoven fabric was measured. Specifically, resin was discharged from each spinneret for one minute into a basket serving as a measuring container to spin fibers, and the weight of the fibers collected in the measuring container was measured to calculate the amount of fiber spun per unit time.

Fig. 7 shows a graph of the spinning amount per unit time of 16 spinning devices No. 1 to 16 equipped in the spinning apparatus of Example 1, and Fig. 8 shows a graph of the spinning amount per unit time of 12 spinning devices No. 1 to 12 equipped in the spinning apparatus of Comparative Example 1. Details of each data are described below.
Example 1
Average spinning amount (Ave): 6.12 g / min
Maximum spinning amount (Max): 6.18 g/min
Minimum spinning amount (Min): 6.02 g/min
・(|Max-Ave|×100)/100=1.0%
・(|Min-Ave|×100)/100=1.6%
(Comparative Example 1)
Average spinning amount (Ave): 5.97 g / min
Maximum spinning amount (Max): 6.66 g/min
Minimum spinning amount (Min): 5.52 g/min
・(|Max-Ave|×100)/100=11.46%
・(|Min-Ave|×100)/100=7.62%

In Comparative Example 1, the difference between the amount of spinning (weight of resin discharged) per unit time for each of the multiple spinnerets and their arithmetic average value exceeds 10% of the arithmetic average value, whereas in Example 1, the difference is 2% or less, and the small variation in the amount of spinning in Example 1 is clear from the graph in Figure 7. From this, it can be seen that in order to discharge resin uniformly from multiple spinnerets for spinning, it is effective for the outlet side flow paths of the multiple fixed-volume spinning structures to be independent of each other (the outlet side flow path extending from the metering pump to the spinnerets does not branch off along the way and does not merge with other outlet side flow paths).

Reference Signs List 1, 1A, 90 Spinning device 2, 91 Constant-volume pump 20 Constant-volume spinning structure 3 Constant-volume discharge section 30 Constant-volume discharge section forming member 4, 92 Liquid feed block 41, 95 Inlet-side flow path 42, 96 Outlet-side flow path 43 First block 44 Second block 5, 93 Spinning device 51, 94 Spinneret 6 Gas flow generator 7 Heater insertion port 8 Pressure sensor and safety valve installation location 9 Pressure sensor 10 Storage section 11 Melt extruder

Claims (8)

A spinning apparatus including a plurality of spinnerets for discharging a raw material liquid containing a resin, a metering pump for feeding the raw material liquid to the spinnerets through an outlet-side flow path, and a metering discharge unit for connecting the metering pump and the outlet-side flow path,
A plurality of the constant-volume dispensing units are provided,
The constant-quantity discharge portion and the spinneret correspond one-to-one to each other, and the constant-quantity spinning structure includes a single spinneret and a single constant-quantity discharge portion corresponding one-to-one to each other, and the outlet-side flow path connecting the two,
The outlet side flow paths of the plurality of quantitative spinning structures are independent of each other,
The plurality of quantitative spinning structures are connected to each other via a single liquid feed block, and the outlet side flow paths of the plurality of quantitative spinning structures are arranged in the liquid feed block,
The liquid feed block has a heating function capable of heating the outlet side flow path of each of the plurality of constant quantity spinning structures . A spinning apparatus including a plurality of spinnerets for discharging a raw material liquid containing a resin, a metering pump for feeding the raw material liquid to the spinnerets through an outlet-side flow path, and a metering discharge unit for connecting the metering pump and the outlet-side flow path,
A plurality of the constant-volume dispensing units are provided,
The constant-quantity discharge portion and the spinneret correspond one-to-one to each other, and the constant-quantity spinning structure includes a single spinneret and a single constant-quantity discharge portion corresponding one-to-one to each other, and the outlet-side flow path connecting the two,
The outlet side flow paths of the plurality of quantitative spinning structures are independent of each other,
The plurality of quantitative spinning structures are connected to each other via a single liquid feed block, and the outlet side flow paths of the plurality of quantitative spinning structures are arranged in the liquid feed block,
The liquid supply block is provided with one or more liquid supply-related parts selected from a filter for filtering the raw material liquid, a pressure sensor for measuring the pressure in the outlet side flow path, and a safety valve for adjusting the pressure in the outlet side flow path, and the liquid supply-related parts are adapted to be compatible with each of the multiple fixed-quantity spinning structures . A spinning apparatus including a plurality of spinnerets for discharging a raw material liquid containing a resin, a metering pump for feeding the raw material liquid to the spinnerets through an outlet-side flow path, and a metering discharge unit for connecting the metering pump and the outlet-side flow path,
A plurality of the constant-volume dispensing units are provided,
The constant-quantity discharge portion and the spinneret correspond one-to-one to each other, and the constant-quantity spinning structure includes a single spinneret and a single constant-quantity discharge portion corresponding one-to-one to each other, and the outlet-side flow path connecting the two,
The outlet side flow paths of the plurality of quantitative spinning structures are independent of each other,
The direction of discharge of the raw material liquid from the multiple spinnerets is the same, and when the multiple spinnerets are viewed from the discharge direction, a virtual rectangle is drawn with a virtual line connecting the two spinnerets that are farthest apart from each other as a diagonal, and the virtual rectangle is divided into thirds in the longitudinal direction. A single metering pump is disposed in the central region of the virtual rectangle, and the single metering pump is connected to the multiple constant-volume discharge units . The spinning device according to claim 1 or 2 , wherein the liquid feed block is configured to be separable into a plurality of parts. The spinning apparatus according to any one of claims 1 to 4 , which is a nanofiber spinning apparatus. A fiber sheet manufacturing apparatus comprising the spinning device according to any one of claims 1 to 5 . A method for producing a fiber sheet, using the production apparatus according to claim 6 . A method for producing fibers, using the spinning apparatus according to any one of claims 1 to 5.

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