Apparatus and method for manufacturing nonwoven fabric

Abstract

The present invention provides a manufacturing device and a manufacturing method of a nonwoven fabric capable of efficiently obtaining a nonwoven fabric of extremely fine fibers having a very small fiber diameter. The manufacturing device of a nonwoven fabric of the present invention is a device for manufacturing a nonwoven fabric by providing a slit-shaped gap (4) between a spinneret (1) having an ejection hole group in which ejection holes (2) for ejecting a molten polymer are arranged in one row and a pair of die lips (3) arranged in opposition with the ejection hole group of the spinneret (1) interposed therebetween, and blowing a gas against the polymer ejected from the ejection holes (2) from the gap (4), characterized in that a pair of widened wall surfaces (6) extending in the direction of polymer ejection are arranged in opposition with the polymer ejected from the ejection holes (2) interposed therebetween, starting from the lower surface of the die lips (3), the angle α formed by the pair of widened wall surfaces (6) is in the range of 60° ≤ α ≤ 120°, and when the intersection of the lower surface of the die lips (3) and the wall surface forming the gap (4) is set as (X) and the intersection of the lower surface of the die lips (3) and the widened wall surface (6) is set as (Y), the interval P between the opposing intersections (X) and the interval H between the opposing intersections (Y) are in the range of 2 ≤ H / P ≤ 15.

Description

Technical Field

[0001] The present invention relates to a device and a method suitable for manufacturing nonwoven fabrics by utilizing a melt-blowing method. Background Art

[0002] One method for producing nonwoven fabrics is the meltblowing method, which involves blowing a high-speed, high-temperature airflow onto a polymer ejected from a spinneret (Japanese: koujin) to stretch the polymer while melting and bonding it to form a web. This web is then collected on a mesh conveyor to produce the nonwoven fabric. The spinneret used in the meltblowing method comprises a spinneret with a group of ejection holes arranged in a row in the width direction and a pair of die lips. The spinneret has an ejection hole group arranged in a row on both sides of the spinneret, and the pair of die lips are arranged so as to face each other with the ejection hole group sandwiched between them. A gap is formed between the spinneret and the die lips. Furthermore, by blowing high-temperature air at high pressure and high speed through the gap onto the polymer ejected from the ejection holes of the spinneret, a nonwoven fabric containing extremely fine fibers can be produced. In recent years, as the use of nonwoven fabrics has gradually expanded to a variety of applications, the demand for nonwoven fabrics with very small fiber diameters has increased with the gradual expansion of high-performance applications such as filters, medical masks, and medical gowns.

[0003] Under such circumstances, various improvement studies have been conducted as a means of reducing the fiber diameter of the non-woven fabric. In order to reduce the fiber diameter, for example, a method of reducing the amount of polymer ejected from a nozzle of a spinneret can be cited, but this will cause the problem of reduced production. In addition, if the ejection amount of the polymer is reduced, the ejection may become unstable. Therefore, in Patent Document 1, regarding a meltblown spinneret, a method is disclosed in which the flow path width of the hot air ejected from the slit (ejection hole) to the molten polymer is minimized after the hot air merges with the polymer at the lower end of the slit, and then gradually expanded. As a result, at the location of the minimum flow path width, the hot air reaches the speed of sound, and then the hot air slowly expands adiabatically, thereby efficiently reducing the fiber diameter.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 51-67411 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, the melt-blow spinneret disclosed in Patent Literature 1 is formed in a shape in which the flow path of the hot air jetted from the slit is temporarily contracted after the polymer is jetted, and then gradually widened. Therefore, the jet flow is inclinedly blown against the web conveyor of the capture web due to the Coanda Effect, and as a result, the fibers sometimes fly like a feather above the web conveyor, making it difficult to form a web. In addition, the polymer jetted from the spinneret plate is easily attached to the contracted flow path portion and the widened flow path, and sometimes, a shot (polymer block) occurs, making it difficult to continuously produce. Further, since the flow path width becomes very narrow locally, the pressure loss becomes high, and it is necessary to increase the performance of the compressor device for supplying the hot air, and sometimes, the equipment cost becomes high. In addition, in the case of the melt-blow spinneret, the effect of the thinning of the fiber diameter can be obtained by increasing the supply pressure of the supplied hot air, but since compressed air is used, the use cost becomes high.

[0009] Therefore, an object of the present application is to provide a nonwoven fabric manufacturing device and a manufacturing method capable of efficiently obtaining a nonwoven fabric of very fine fibers having a very small fiber diameter.

[0010] Means for solving the problem

[0011] The present application for solving the above problem adopts any one of the following configurations.

[0012] (1) A nonwoven fabric manufacturing device which is a device for manufacturing a nonwoven fabric by providing a gap in the shape of a slit between a spinneret plate having a jet hole group in which jet holes for jetting a molten polymer are arranged in one row and a pair of die lips arranged in opposition to each other with the jet hole group of the spinneret plate interposed therebetween, and blowing a gas against the polymer jetted from the jet holes from the gap, characterized in that

[0013] a pair of widened wall surfaces extending in the polymer jetting direction are arranged in opposition to each other with the lower surface of the die lip as a starting point,

[0014] the angle α formed by the pair of widened wall surfaces is in the range of 60° ≤ α ≤ 120°, and

[0015] when the intersection of the lower surface of the die lip and the wall surface forming the gap is set as X, and the intersection of the lower surface of the die lip and the widened wall surface is set as Y, the interval P between the opposing intersections X and the interval H between the opposing intersections Y are in the range of 2 ≤ H / P ≤ 15.

[0016] (2) The nonwoven fabric manufacturing device according to the aforementioned (1), in which the angle β formed by the lower surface of the die lip and the polymer jetting direction is 70° ≤ β ≤ 120°.

[0017] (3) The nonwoven fabric manufacturing apparatus according to (1) or (2) above, wherein a length γ of the widening wall surface in the polymer ejection direction is 10 mm or more.

[0018] (4) The nonwoven fabric manufacturing apparatus according to any one of (1) to (3), wherein the widening wall surface is movable in a direction intersecting with the polymer ejection direction.

[0019] (5) The nonwoven fabric manufacturing apparatus according to any one of (1) to (4), wherein the arithmetic mean roughness Ra of the widened wall surface is 100 μm or less.

[0020] (6) The nonwoven fabric manufacturing apparatus according to any one of (1) to (5) above, further comprising a heating mechanism for the widened wall surface.

[0021] (7) A method for producing a nonwoven fabric, wherein the method uses the apparatus according to any one of (1) to (6).

[0022] In the present invention, the "lower surface of the die lip" refers to the surface of the die lip that faces the downstream side in the polymer ejection direction.

[0023] In the present invention, the "slit-shaped gap" refers to a rectangular gap that is arranged substantially parallel to the ejection hole group arranged in a row and has a cross section that is long in one direction.

[0024] In the present invention, the angle α formed by a pair of widening walls is as follows: Figure 1 As shown, the angle is essentially formed by the extension line of the planar wall in the upstream direction of the polymer ejection direction, but in the case of a widening wall having a portion whose widening angle changes along the polymer ejection direction together with the planar portion, for example, in the case of a pair of planar walls having an R portion on the die lip side, the angle formed by the extension line of the pair of planar portions is used.

[0025] The term "intersection of the lower surface of the die lip and the wall surface forming the gap" also refers to the intersection of two planes. However, if the position corresponding to the intersection is formed by a rounded portion, the intersection of the extension lines of the respective planes is used. Furthermore, the term "intersection of the lower surface of the die lip and the widened wall surface" refers to the intersection of the substantially planar widened wall surface and the substantially planar lower surface of the die lip. However, if the position corresponding to the intersection is formed by a rounded portion, the intersection of the extension lines of the respective planes is used.

[0026] Effects of the Invention

[0027] According to the present invention, by controlling the jet flow immediately below the spinneret, it is possible to prevent defects such as shot blasting and stably produce a nonwoven fabric of ultrafine fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] [ Figure 1 ] Figure 1 This is a schematic cross-sectional view showing one embodiment of the melt-blowing spinneret in the present invention.

[0029] [ Figure 2 ] Figure 2 This is a schematic cross-sectional view of a conventional meltblowing spinneret.

[0030] [ Figure 3 ] Figure 3 This is a schematic side view showing one embodiment of the nonwoven fabric production apparatus of the present invention.

[0031] [ Figure 4 ] Figure 4 Schematic diagram showing the direction of airflow directly below a meltblowing spinneret in a conventional example.

[0032] [ Figure 5 ] Figure 5 Schematic diagram showing the direction of airflow directly below the meltblowing spinneret in the present invention.

[0033] [ Figure 6 ] Figure 6 Schematic diagram showing the direction of airflow directly below a meltblowing spinneret in a conventional example.

[0034] [ Figure 7 ] Figure 7 This is a schematic cross-sectional view showing another embodiment of the melt-blowing spinneret of the present invention.

[0035] [ Figure 8 ] Figure 8 This is a schematic cross-sectional view showing another embodiment of the melt-blowing spinneret in the present invention.

[0036] [ Figure 9 ] Figure 9 This is a schematic cross-sectional view showing an embodiment of a melt-blowing spinneret that is not included in the present invention.

[0037] [ Figure 10 ] Figure 10 This is a schematic cross-sectional view showing another embodiment of a meltblowing spinneret that is not included in the present invention.

[0038] [ Figure 11 ] Figure 11 This is a schematic cross-sectional view showing another embodiment of the melt-blowing spinneret in the present invention. DETAILED DESCRIPTION

[0039] Below, with reference to the attached Figure 1 The nonwoven fabric manufacturing apparatus and manufacturing method of the present invention will be described in detail. Figure 1This is a schematic cross-sectional view showing one embodiment of a melt-blowing spinneret used in the present invention. Figure 2 This is a schematic cross-sectional view of a conventional meltblowing spinneret that does not have a widening wall surface on the lower surface of the die lip. Figure 3 This is a schematic side view showing an example of a nonwoven fabric production apparatus. Figure 4 This figure shows the direction of airflow directly below a meltblowing die head in a conventional example in which no widening wall surface is provided on the lower surface of the die lip. Figure 5 The direction of the air flow directly below the meltblowing die head in the embodiment of the present invention is shown. Figure 6 This figure shows the direction of airflow directly below the meltblowing spinneret in another conventional example in which a widening wall surface is provided on the lower surface of the die lip, but which is not included in the present invention. Figure 7 、 8 This is a schematic cross-sectional view showing another embodiment of the meltblowing spinneret in the present invention. Figures 4 to 6 In the figure, the direction of the arrow indicates the direction of airflow. Furthermore, the term "directly below the meltblown spinneret" herein refers to the region below the ejection orifice of the spinneret of the meltblown spinneret, relative to the direction of polymer ejection. These figures are simplified schematic diagrams for accurately conveying the key points of the present invention. The meltblown spinneret in the present invention is not particularly limited, and aspects such as dimensional ratios may vary depending on the embodiment.

[0040] like Figure 3 As shown in FIG, the nonwoven fabric manufacturing apparatus used in the embodiment of the present invention is composed of a polymer introduction pipe 8, a melt-blowing spinneret 9, a collection net conveyor 10, a roller 11, etc. Figure 1 As shown, the melt-blowing spinneret 9 has a spinneret 1 and a pair of die lips 3, wherein the spinneret 1 has a plurality of ejection holes 2 in one direction ( Figure 1 The pair of die lips 3 are arranged to face each other with the ejection hole group of the spinneret 1 interposed therebetween, and a slit-like gap 4 is formed between the spinneret 1 and each die lip 3.

[0041] In such an apparatus configuration, a polymer is supplied from a polymer inlet pipe 8 to a melt-blowing die 9, and simultaneously, a gas such as high-temperature air is also supplied to the melt-blowing die 9, and the molten polymer is ejected from the ejection hole 2 of the spinneret 1. At this time, the polymer can be supplied directly from the polymer inlet pipe 8 to the melt-blowing die 9, or it can be introduced into the melt-blowing die 9 via a spinneret including a coat hanger die (not shown). Then, a gas such as high-temperature air is blown from the gap 4 formed between the spinneret 1 and the die lip 3 toward the polymer continuously ejected from the ejection hole 2, thereby pulling the polymer and reducing its diameter, while causing the polymer to melt and bond to form a web 12. The web 12 is captured by a capture net conveyor 10 and wound on a roller 11 in the form of a non-woven fabric. It should be noted that, instead of using a capture net conveyor 10, the polymer can be directly ejected onto a rotating roller and blown with a gas such as high-temperature air to form the web 12.

[0042] Here, the polymer ejected from the ejection hole 2 is in a low-viscosity state and is pulled and reduced in diameter in a region extending from the ejection hole 2 to several millimeters in the direction of the polymer ejection (referred to as the stretching region). Therefore, it is important to efficiently exert the pulling force in this stretching region. Here, the pulling force F is proportional to the square of the airflow velocity v and the length of the stretching region l, as shown in Formula (A), assuming that CF is the constant, the density ρ of the blowing gas, the gas velocity v in the stretching region, the circumferential length c of the polymer in the linear form, and the length l of the stretching region.

[0043] F=CF×ρ×v 2 ×c×l formula (A)

[0044] Therefore, as a method of efficiently increasing the pulling force F, it can be considered to increase the gas wind speed v in the stretching section and the length l of the stretching section.

[0045] As a means for this, for example, as shown in Patent Document 1, after the flow paths of the ejected air flows merge at the lower end of the slit, the flow path width is minimized and then expanded, thereby increasing the gas velocity v. However, according to this method, Figure 6 As shown, after the polymer is ejected, a very narrow portion of the flow path extends along the direction of polymer ejection. Therefore, the jet tends to flow along one side of the wall due to the Coanda effect. As a result, the polymer ejected from the ejection hole 2 cannot flow straight in the ejection direction, and the length l of the stretching zone becomes extremely short. Furthermore, as described above, the polymer is ejected at an angle relative to the collection net conveyor 10, making it difficult to stably produce ultrafine fiber nonwoven fabrics.

[0046] In addition, generally speaking, in a meltblown spinneret, a pair of gaps 4 are used to blow out higher-speed gas, and a jet is formed after the gas collides with the gaps 4. Therefore, the airflow turbulence tends to become very large, and it is very difficult to stably form a jet portion directly below the spinneret. It should be noted that the jet portion refers to the high-speed region of the airflow blown out from the gap 4 (generally defined as the region with a Mach number of 0.3 or more), and the interval with a high wind speed v in the jet portion becomes the stretching interval. Therefore, in order to stably manufacture nonwoven fabrics of ultrafine fibers, it is necessary to stably and sufficiently ensure the length l of the stretching interval directly below the meltblown spinneret, and to increase the wind speed v in this interval.

[0047] Therefore, the present inventors have conducted repeated and in-depth research on the above-mentioned problems that have not been considered in the prior art, and as a result, they have discovered the new technology of the present invention. Figure 1 、 5 As shown, a pair of widening walls 6 are arranged, extending in the polymer ejection direction, with the lower surface of the die lip 3 as the starting point. Furthermore, the angle α formed by the pair of widening walls 6 is set within the range of 60° ≤ α ≤ 120°. Furthermore, assuming the intersection point X of the lower surface of the die lip 3 and the wall forming the gap 4, and the intersection point Y of the lower surface of the die lip 3 and the widening walls 6, the interval P [mm] between the opposing intersection points X and the interval H [mm] between the opposing intersection points Y are within the range of 2 ≤ H / P ≤ 15.

[0048] Here, the conventional example ( Figure 4 ) and an embodiment of the present invention having a widened wall surface having the above-mentioned structure ( Figure 5 ) is used to illustrate the difference in the shape of the airflow directly below the spinneret. Figure 4 In the embodiment of the conventional example shown, high-speed gases blown from a pair of gaps 4 collide with each other to form a jet portion, and the gas in the jet portion diffuses downward from the gap at the relative intersection X. At this time, the accompanying flow flows into the jet portion approximately vertically along the lower surface of the die lip 3, and while being drawn into the accompanying flow, the jet portion gradually widens. By using this jet portion, the fibrous polymer is stretched, decelerated, and lands on the net conveyor 10. On the other hand, in Figure 5In the embodiment of the present invention shown, relative to the jet portion blown out from a pair of gaps 4, the accompanying flow flows along the widening wall surface 6 and the lower surface of the die lip 3, and flows into the jet portion from a direction opposite to the mainstream direction of the jet portion (downward in the figure). As a result, in the jet portion directly below the spinneret, the jet width w is narrowed by the accompanying flow pressure flowing in from both sides of the spinneret 1, the cross-sectional area of ​​the jet portion becomes smaller, and the wind speed v in the stretching zone is faster than that of the conventional example. In addition, the air flow flows along the widening wall surface 6 in a manner opposite to the mainstream direction of the jet, thereby suppressing the widening of the jet portion. As a result, the jet portion becomes longer in the direction of polymer ejection, and the stretching zone l increases. In this way, in the meltblown spinneret of the embodiment of the present invention, the length l of the stretching zone and the wind speed v in the zone are increased, so that a non-woven fabric of ultrafine fibers can be stably produced.

[0049] In the present invention, as described above, the angle α formed by the pair of opposed widening wall surfaces 6 satisfies the relationship of 60°≤α≤120°, and the interval P [mm] between the opposing intersection points X sandwiching the ejection hole 2 and the interval H [mm] between the opposing intersection points Y sandwiching the ejection hole 2 are adjusted so as to satisfy the relationship of 2≤H / P≤15. However, even if H / P satisfies the relationship of 2≤H / P≤15, in the case where the angle α is α<60° as shown in Patent Document 1, Figure 9 As shown, the ejected polymer will be biased toward the widened wall surface 6 on one side, making it difficult to stably obtain a nonwoven fabric of ultrafine fibers. On the other hand, when the angle α is α>120°, the accompanying flow cannot narrow the jet portion, and the diameter reduction effect cannot be achieved.

[0050] In addition, even if the angle α satisfies the relationship of 60°≤α≤120°, in the case of H / P<2, as Figure 10 As shown, the ejected polymer will be biased toward the widened wall surface 6 on one side, making it difficult to stably produce a nonwoven fabric made of ultrafine fibers. Furthermore, when H / P is greater than 15, the accompanying flow cannot narrow the jet portion, failing to achieve a thinning effect. In the present invention, by adjusting the jet directly below the spinneret 1 to satisfy the conditions of 60° ≤ α ≤ 120° and 2 ≤ H / P ≤ 15, it is possible to control the jet flow and stably produce a nonwoven fabric made of ultrafine fibers.

[0051] The angle α is preferably within the range of 70° ≤ α ≤ 110°. Furthermore, H / P is preferably within the range of 3 ≤ H / P ≤ 8. Specifically, the interval P [mm] determines the initial width of the jet, while the interval H [mm] determines the expansion of the jet on the downstream side of the jet. Therefore, the ratio H / P is an important parameter for jet control and, consequently, for jet tapering.

[0052] In the present application, the interval P [mm] between the opposing intersection points X sandwiching the discharge hole 2 is preferably in the range of 0.4 ≤ P ≤ 4.0. The air gap width needs to be uniformly set throughout the arrangement direction of the discharge holes (the device width), and by setting 0.4 ≤ P, the air gap width is easily set uniformly throughout the device width. On the other hand, by setting P ≤ 4.0, the jet velocity is accelerated, and the effect of the fine diameter is more easily achieved.

[0053] It is preferable that the pair of widened wall surfaces 6 be capable of arbitrarily changing the inclination of each widened wall surface 6. The member 5 constituting the widened wall surface 6 can be either a block or a plate, and can be integrally formed with the die lip 3 and the widened wall surface 6. Note that the die lip is a portion that contributes to the formation and restriction of the flow path of the gas blown against the polymer together with the spinneret, and in the case of being integrally formed, the lower surface of the portion including the front end (intersection point X) of the blown gas becomes the "lower surface of the die lip".

[0054] In the present application, as shown in FIG. 1, the front end of the spinneret 1 can be located at the same position as the lower surface of the die lip 3 with respect to the polymer discharge direction, as shown in FIG. 2, the front end of the spinneret 1 can also be located on the more upstream side than the lower surface of the die lip, and furthermore, can be located on the more downstream side. Figure 1 Figure 11 In the present application, as shown in FIG. 1, the front end of the spinneret 1 can be located at the same position as the lower surface of the die lip 3 with respect to the polymer discharge direction, as shown in FIG. 2, the front end of the spinneret 1 can also be located on the more upstream side than the lower surface of the die lip, and furthermore, can be located on the more downstream side.

[0055] In the present application, as shown in FIG. 1, the front end of the spinneret 1 can be located at the same position as the lower surface of the die lip 3 with respect to the polymer discharge direction, as shown in FIG. 2, the front end of the spinneret 1 can also be located on the more upstream side than the lower surface of the die lip, and furthermore, can be located on the more downstream side. Figure 7 In the present application, as shown in FIG. 1, the front end of the spinneret 1 can be located at the same position as the lower surface of the die lip 3 with respect to the polymer discharge direction, as shown in FIG. 2, the front end of the spinneret 1 can also be located on the more upstream side than the lower surface of the die lip, and furthermore, can be located on the more downstream side.

[0056] ​​

[0057] In the present invention, the widening member 5 constituting the widening wall 6 is preferably movable horizontally along the lower surface of the die lip 3. This is because, at the start of operation of the device, when polymer ejection is unstable, there is a risk of polymer adhering to the widening wall 6. Therefore, at the start of operation, for example, the widening wall 6 is separated from the ejection hole 2 of the spinneret 1, and when the ejection state stabilizes, the widening member 5 is moved to a predetermined position. The horizontal movement distance is preferably 10 mm or more, and particularly preferably 50 mm or more. In this case, the widening member 5 is preferably moved using a push-pull bolt, a feed screw, or a track mechanism.

[0058] In addition, in the present invention, it is preferred to have a heating mechanism for the widening wall 6. Specifically, for example, the widening component 5 constituting the widening wall 6 is preferably heated by a heating mechanism such as a heater. In the present invention, for example, the accompanying flow at room temperature will flow along the widening wall 6 toward the spinneret 1, thereby easily cooling the front end of the spinneret 1 through the widening component 5. As a result, the melt viscosity of the polymer during ejection increases, thereby hindering the efficient stretching of the fiber and risking a reduction in the effect of diameter reduction. Therefore, it is preferred to provide a heating mechanism for the widening wall 6 to prevent the melt viscosity of the polymer from increasing during ejection. Regarding the type of heater, a rod-shaped or plate-shaped one can be cited, but from the viewpoint of uniformity, a plate-shaped one is more preferred. Regarding the heat of the heater, it is preferably 1.2KW / m or more. In addition, instead of the heating mechanism, the surface of the widening component can also be covered with an insulating plate with low thermal conductivity, and regarding the thermal conductivity, it is preferably 1.0W / m / K or less.

[0059] Furthermore, in the present invention, Figure 8 As shown, the widening wall surface 6 may also have a structure having, in addition to the flat portion, an R-shaped portion that gradually approaches the lower surface of the lip 3 near the lower surface of the lip 3. In the present invention, as described above, the emphasis is on suppressing the widening of the air jet portion immediately below the spinneret by the inflow of the accompanying flow along the widening wall surface 6. Therefore, by forming the R-shaped portion within a range that does not affect the main flow of the accompanying flow, the diameter reduction effect can also be achieved.

[0060] In the present invention, the arithmetic mean roughness Ra of the widening wall is preferably 100 μm or less. If the arithmetic mean roughness Ra of the widening wall is Ra>100 μm, eddy currents are easily generated due to the unevenness of the widening wall 6, and the turbulence of the accompanying flow becomes greater, which may reduce the effect of the diameter reduction. In addition, the direction of the nodes generated by the processing of the widening wall 6 is different from the direction of the nodes generated by the processing of the widening wall 6. Figure 5 The direction of the airflow near the widening wall surface 6 shown is parallel, which can suppress the generation of vortex flow and is therefore preferred.

[0061] As the material of the widening member used in the present invention, metal materials such as stainless steel and aluminum, and plastic materials such as glass fiber can be preferably used.

[0062] The present invention is highly versatile and can be applied to the production of known meltblown nonwoven fabrics. Therefore, the polymer constituting the nonwoven fabric is not particularly limited. For example, polyester, polyamide, polyphenylene sulfide, polyethylene, polypropylene, etc. can be cited as an example of a polymer constituting the nonwoven fabric. The MFR (melt flow rate) of the polymer is preferably 300 to 1500 g / 10 minutes, and particularly preferably 900 to 1300 g / 10 minutes. The above-mentioned polymer may contain various functional particles or organic compound additives such as matting agents such as titanium dioxide, silicon oxide, potassium ions, anti-coloring agents, stabilizers, antioxidants, deodorants, flame retardants, yarn friction reducers, coloring pigments, surface modifiers, etc., within a range that does not impair the stability of the yarn production, and may also contain copolymers. In addition, it may be a polymer solution obtained by dissolving a polymer such as cellulose, polysulfone, polyetherimide, polyacrylonitrile in a solvent. The spinning temperature of the polymer is based on the melting point of the polymer used and is preferably set to below the melting point + 60°C.

[0063] In the present invention, the gas blown from gap 4 is preferably air, which is the most economical. However, a mixed gas, steam, saturated steam, or superheated steam may also be used. To increase the pulling force, as shown in equation (A), the gas density ρ is also related to the gas density, so a gas with a high density is preferably selected. The gas temperature can be set within a range from the temperature of the ejected polymer to below +50°C.

[0064] Furthermore, in the present invention, the flow rates of the gas supplied from the left and right gaps 4 may be different.

[0065] Example

[0066] Hereinafter, the effects of the production apparatus and production method of the present invention will be specifically described with reference to Examples. It should be noted that the methods for measuring the characteristic values ​​in the Examples are as follows.

[0067] <Airflow deviation>

[0068] Airflow deviation was evaluated during spinning using an anemometer (Model 6501 series, Kanomax Co., Ltd., Japan) at the center of the apparatus width. Specifically, the anemometer probes were placed 10 mm downstream of the spinneret's outlet surface in the polymer ejection direction and 2 mm inward from the outlet wall on both sides of the widening wall. The wind speed was measured every 1 second, and the 10-second average was used. Airflow deviation was determined to be present if the wind speed values ​​differed by a factor of 5 or more between the left and right walls.

[0069] <Average fiber diameter>

[0070] After removing the widthwise center 50 mm from the nonwoven fabric collected on the collection net conveyor, small pieces were randomly collected. Each small piece was photographed using an electron microscope, and 100 fibers were randomly selected to measure the fiber diameters and calculate the arithmetic mean.

[0071] (Comparative Example 1)

[0072] use Figure 2 The meltblown spinneret shown (i.e., without the widened wall surface on the lower surface of the die lip) was used to produce nonwoven fabrics. As the raw material resin, a polypropylene resin with a weight of 2.16 kg and a melt flow rate of 1100 g / 10 minutes at 230°C was used in accordance with ASTM-D1238. The following settings were used: a molten resin temperature of 280°C, 150 spinneret holes, a pitch of 1 mm between the spinneret holes, a spinneret hole diameter of 0.4 mm, a single hole discharge rate of 0.1 g / min, a gap width of 1.5 mm for supplying hot air on the lower surface of the die lip, and a hot air flow rate of 560 Nm. 3 The nonwoven fabric was produced under the conditions shown in Table 1. The test results are shown in Table 1. In Comparative Example 1, the nonwoven fabric could be collected on the conveyor belt, and the average fiber diameter was 1.1 μm.

[0073] (Examples 1 to 10, Comparative Examples 2 to 6)

[0074] use Figure 1 The meltblowing die shown (i.e., having a widened wall surface on the lower surface of the die lip) was used to produce nonwoven fabrics. As the raw material resin, a polypropylene resin with a weight of 2.16 kg and a melt flow rate of 1100 g / 10 minutes at 230°C was used in accordance with ASTM-D1238. The following settings were used: a molten resin temperature of 280°C, 150 spinneret holes, a pitch of 1 mm between the spinneret holes, a spinneret hole diameter of 0.4 mm, a single hole discharge rate of 0.1 g / min, a gap width of 1.5 mm for supplying hot air on the lower surface of the die lip, and a hot air flow rate of 560 Nm. 3 / (hr·m), the widening member was not heated by a heater, and the nonwoven fabric was produced under the conditions shown in Tables 2 to 4. The test results are shown in Tables 2 to 4.

[0075] In Examples 1 to 10, where the angle α formed by the opposing widening walls was within the range of 60° to 120° and the ratio H / P of the interval P between the intersection points X to the interval H between the intersection points Y was within the range of 2 to 15, the jet flow directly below the spinneret was controlled, enabling stable production of ultrafine fiber nonwoven fabrics. In Examples 6 and 8, occasional resin accumulation on the widening walls was observed, necessitating regular removal of the adhered polymer. However, this did not hinder the continuous and stable production of nonwoven fabrics.

[0076] On the other hand, in Comparative Example 2, the angle α formed by the relative widening walls was changed to 50°, and the ratio H / P of the interval P between the intersection points X and the interval H between the intersection points Y was changed to 1. In addition, the manufacture of the non-woven fabric was attempted in the same manner as in Example 2. As a result, the air flow flowed along the wall on one side, and the non-woven fabric could not be captured on the conveyor belt.

[0077] In Comparative Example 3, the production of nonwoven fabric was attempted in the same manner as in Example 2 except that the angle α between the opposing widening walls was changed to 50°. However, the air flow flowed along one wall surface, and the nonwoven fabric could not be collected on the conveyor.

[0078] In Comparative Example 4, the production of nonwoven fabric was attempted in the same manner as in Example 2 except that the ratio H / P of the interval P between the intersection points X and the interval H between the intersection points Y was changed to 1. However, the air flow flowed along the wall on one side, and the nonwoven fabric could not be captured on the conveyor belt.

[0079] In Comparative Example 5, the ratio H / P of the interval P between the intersection points X to the interval H between the intersection points Y was changed to 21. Except for this, the manufacture of the nonwoven fabric was attempted in the same manner as in Example 2. As a result, although a nonwoven fabric was obtained, the accompanying flow could not narrow the ejected airflow, and the effect of reducing the diameter could not be achieved.

[0080] In Comparative Example 6, the production of nonwoven fabric was attempted in the same manner as in Example 4 except that the angle α formed by the relative widening wall surfaces was changed to 150°. As a result, although a nonwoven fabric was obtained, the accompanying flow could not narrow the ejected airflow, and the effect of reducing the diameter could not be achieved.

[0081] (Comparative Example 7)

[0082] use Figure 2 The melt-blown spinneret shown (i.e., the widened wall surface without the lower surface of the die lip) has a gap width of 0.5 mm and a hot air flow rate of 450 Nm 3 / (hr·m), and other conditions were the same as those in Comparative Example 1, and nonwoven fabric was produced. The test results are shown in Table 5. In Comparative Example 7, the nonwoven fabric could be collected on the conveyor, and the average fiber diameter was 1.1 μm.

[0083] (Examples 11 to 13, Comparative Examples 8 and 9)

[0084] use Figure 1 The melt-blown spinneret shown (i.e., the widened wall surface on the lower surface side of the die lip) is set to a gap width of 0.5 mm and a hot air flow rate of 450 Nm 3 / (hr·m), the angle α between the relative walls is 90°, the angle β between the lower surface of the die lip and the polymer ejection direction is 90°, the length γ of the widened wall in the polymer ejection direction is 30 mm, the arithmetic mean roughness Ra of the widened wall is 12.5 μm, the widened part is not heated by a heater, and the non-woven fabric is manufactured under the conditions shown in Table 5.

[0085] In Examples 11 to 13, in which the ratio H / P of the interval P between the intersection points X to the interval H between the intersection points Y was within the range of 2 to 15, the jet flow immediately below the spinneret could be controlled, and nonwoven fabrics of ultrafine fibers could be stably produced.

[0086] In Comparative Example 8, the production of nonwoven fabric was attempted in the same manner as in Example 11 except that the ratio H / P of the interval P between the intersection points X and the interval H between the intersection points Y was changed to 1. However, the air flow flowed along the wall on one side, and the nonwoven fabric could not be captured on the conveyor belt.

[0087] In Comparative Example 9, the ratio H / P of the interval P between the intersection points X to the interval H between the intersection points Y was changed to 25. Except for this, the manufacture of the nonwoven fabric was attempted in the same manner as in Example 11. As a result, although a nonwoven fabric was obtained, the accompanying flow could not narrow the ejected airflow, and the effect of reducing the diameter could not be achieved.

[0088] (Example 14)

[0089] use Figure 1 The melt-blown spinneret shown (i.e., the widened wall surface on the lower surface side of the die lip) is set to a gap width of 0.5 mm and a hot air flow rate of 450 Nm 3 / (hr·m), the angle α formed by the relative walls is 90°, the angle β formed by the lower surface of the die lip and the polymer ejection direction is 90°, the length γ of the widening wall in the polymer ejection direction is 30 mm, the arithmetic mean roughness Ra of the widening wall is 12.5 μm, and the widening part is heated at 2.0 KW / m using a plate heater (heating surface: the opposite side of the widening wall), and the non-woven fabric is manufactured under the conditions shown in Table 5.

[0090] Compared with Example 12 in which no heating and widening member was used, a nonwoven fabric containing finer ultrafine fibers could be stably produced.

[0091] [Table 1]

[0092] surface

[0093] Comparative Example 1 Angle a of the relative widening wall surface degrees (°) - H / P - - Angle β of the lower surface of the die lip to the polymer ejection direction degrees (°) 90 Length γ of the widening wall surface in the polymer ejection direction mm - Arithmetic mean roughness Ra of the widening wall surface μm - Heating of the widening member using a heater - No Deflection of the air flow - No Average fibre diameter μm 1.1

[0094] [Table 2]

[0095]

[0096] [Table 3]

[0097]

[0098] [Table 4]

[0099]

[0100] [Table 5]

[0101]

[0102] Industrial applicability

[0103] The nonwoven fabric produced by the manufacturing device and manufacturing method of the present invention can be applied to sanitary materials such as filters for industrial materials, diapers, sanitary products, medical masks, medical gowns, pollen protection masks, curtains, automotive materials, filters for liquid filtration, lining paper, industrial materials such as car brushes, food packaging materials, wrapping cloth, belt yarn, shoe materials, heating pads (Japanese: kairo), tea bags, daily materials such as cleaning covers, overall covering materials (Japanese: べたがけ), agricultural materials such as agricultural pots, roofing materials, civil engineering stabilization sheets, thermal insulation materials, flooring materials, building materials such as house cladding, civil engineering materials, etc., but its application range is not limited to these.

[0104] Description of Reference Numerals

[0105] 1 Spinneret

[0106] 2 ejection holes

[0107] 3 Die Lip

[0108] 4 Gap

[0109] 5. Widening components

[0110] 6. Widen the wall

[0111] 7 Main polymer trajectories after ejection

[0112] 8 Polymer inlet tube

[0113] 9 Meltblown spinneret

[0114] 10. Capture Net Conveyor

[0115] 11 rollers

[0116] 12 Net

[0117] 13 Boundary between the jet and non-jet areas

[0118] X The intersection of the lower surface of the die lip and the wall forming the gap

[0119] The intersection of the lower surface of the Y-lip and the widened wall

[0120] α is the angle between the widening walls

[0121] β The angle between the lower surface of the die lip and the direction of polymer ejection

[0122] γ is the length of the widening wall in the direction of polymer ejection

[0123] l Length of the stretching interval

[0124] w jet width

[0125] H is the distance between the intersection points Y facing each other with the ejection hole interposed therebetween.

[0126] P is the distance between the intersection points X that face each other with the ejection hole interposed therebetween.

Claims

1. A nonwoven fabric manufacturing apparatus comprising a spinneret having a group of ejection holes arranged in a row for ejecting a molten polymer and a pair of die lips disposed opposite to each other with the group of ejection holes of the spinneret interposed therebetween, wherein a slit-like gap is provided between the spinneret, the group of ejection holes being arranged in a row, and a pair of die lips being disposed opposite to each other with the group of ejection holes of the spinneret being interposed therebetween, and a gas is blown from the gap toward the polymer ejected from the ejection holes to manufacture the nonwoven fabric, wherein: A pair of widening wall surfaces extending in the polymer ejection direction are arranged with the lower surface of the die lip as a starting point so as to face each other while sandwiching the polymer ejected from the ejection hole. The angle α formed by the pair of widening walls is in the range of 60°≤α≤120°, and When the intersection point of the lower surface of the die lip and the wall surface forming the gap is set to X, and the intersection point of the lower surface of the die lip and the widening wall surface is set to Y, the interval P between the opposite intersection points X and the interval H between the opposite intersection points Y are in the range of 2≤H / P≤15.

2. The nonwoven fabric manufacturing apparatus according to claim 1, wherein: The angle β formed between the lower surface of the die lip and the polymer ejection direction is 70°≤β≤120°.

3. The nonwoven fabric manufacturing apparatus according to claim 1 or 2, wherein: The length γ of the widening wall surface in the polymer ejection direction is 10 mm or more.

4. The nonwoven fabric manufacturing apparatus according to claim 1 or 2, wherein: The widening wall surface is movable in a direction intersecting the polymer ejection direction.

5. The nonwoven fabric manufacturing apparatus according to claim 1 or 2, wherein: The arithmetic mean roughness Ra of the widened wall surface is 100 μm or less. The nonwoven fabric manufacturing apparatus according to claim 1 or 2, further comprising a heating mechanism for the widening wall surface.

7. A method for producing a nonwoven fabric, wherein: The manufacturing method uses the apparatus according to any one of claims 1 to 6.

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