Nonwoven fabric manufacturing apparatus and method for manufacturing nonwoven fabric

Abstract

To provide a nonwoven fabric using polylactic acid-based resin as a raw material.SOLUTION: A nonwoven fabric manufacturing device comprises: a discharge portion to melt and discharge polylactic acid-based resin; a drawing portion to draw the polylactic acid-based resin by air flow; a cooling portion that is disposed between the discharge portion and the drawing portion and blows cooling air to the polylactic acid-based resin; a sheet conveyance portion to collect fibers of the polylactic acid-based resin drawn by the drawing portion, form the fibers into a sheet-like nonwoven fabric and convey the nonwoven fabric in a transfer direction; and a fusion portion to fuse and bond the fibers with each other by heating the fibers of the polylactic acid-based resin. Drawing speed at which the drawing portion draws the polylactic acid-based resin is 180,000 / min or more.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a nonwoven fabric manufacturing apparatus. [Background technology]

[0002] BACKGROUND ART Conventionally, methods for producing nonwoven fabrics containing multiple fiber layers have been known (for example, Patent Document 1). Nonwoven fabrics are generally made from thermoplastic resins such as polypropylene (PP). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-70875 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, biodegradable nonwoven fabrics that decompose naturally have been attracting attention. Polylactic acid (PLA) is used as the raw material for biodegradable nonwoven fabrics. Because the crystallization rate of polylactic acid is slower than that of thermoplastic resins such as polypropylene, there is a problem in that polylactic acid does not crystallize under the manufacturing conditions for nonwoven fabrics made from conventional thermoplastic resins. When attempting to pass uncrystallized polylactic acid fibers through a heated roll to fuse the fibers together, the fibers stick to the heated roll, which makes it impossible to manufacture nonwoven fabrics using polylactic acid-based resins as the raw material.

[0005] An object of the present invention is to provide a nonwoven fabric using a polylactic acid resin as a raw material. [Means for solving the problem]

[0006] In order to solve the above problems, in the present invention, the stretching speed for stretching the polylactic acid resin is set to 180,000 / min or more.

[0007] In detail, the present invention relates to a nonwoven fabric manufacturing apparatus for manufacturing nonwoven fabric made from polylactic acid-based raw materials, and includes a discharge section that melts and discharges the polylactic acid-based resin, a stretching section that stretches the polylactic acid-based resin using an airflow, a cooling section that is arranged between the discharge section and the stretching section and blows cooling air onto the polylactic acid-based resin, a sheet conveying section that collects the fibers of the polylactic acid-based resin stretched by the stretching section on a conveying surface and conveys them in a transfer direction while forming them into a sheet-like nonwoven fabric, and a fusion section that heats the fibers of the polylactic acid-based resin to fuse the fibers together, and the stretching section stretches the polylactic acid-based resin at a stretching speed of 180,000 / min or more.

[0008] The discharge unit may have a nozzle for discharging the polylactic acid resin, and the amount of the polylactic acid resin discharged from the nozzle may be 0.5 g / min / hole or less.

[0009] The fusion unit may have a heat roll for heating the polylactic acid resin fibers, and the surface temperature of the heat roll may be 110° C. or higher.

[0010] The surface temperature of the heat roll may be 145° C. or higher.

[0011] The fused portion may be formed by embossing the fibers, and the embossed area ratio may be 6% or more and 20% or less.

[0012] The conveying speed at which the sheet conveying unit conveys the polylactic acid resin fibers is 40 m / min. The speed may be 120 m / min or more.

[0013] The cooling section may be capable of receiving air from the outside.

[0014] The discharge section may spin out a filament aggregate of the polylactic acid-based resin. [Effects of the Invention]

[0015] According to the present invention, a nonwoven fabric using a polylactic acid resin as a raw material can be realized. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a plan view of a nonwoven fabric according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a nonwoven fabric according to an embodiment. [Figure 3] FIG. 3 is a table showing the manufacturing conditions of the nonwoven fabric. [Figure 4] FIG. 4 is a table showing the results of an experiment on the relationship between the surface temperature of a heated roll and the degree of adhesion to the heated roll when polylactic acid fibers are passed through the heated roll. [Figure 5] FIG. 5 is a graph showing the fiber velocity during the spinning process. [Figure 6] FIG. 6 is a flowchart showing a method for producing a nonwoven fabric according to an embodiment. [Figure 7] FIG. 7 is a diagram showing a nonwoven fabric manufacturing apparatus for manufacturing the nonwoven fabric according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the configurations of the following embodiments are merely examples, and the present invention is not limited to the configurations of these embodiments.

[0018] <Embodiment> Fig. 1 is a plan view of nonwoven fabric C according to this embodiment as seen from above. Fig. 2 is a cross-sectional view of nonwoven fabric C in the CD direction when cut along line AA shown in Fig. 1. Nonwoven fabric C is a sheet with the longitudinal direction in the MD direction, and is composed of multiple layers.

[0019] As shown in FIG. 2, the nonwoven fabric C has a layered structure in which three fiber layers C1 are laminated. In the nonwoven fabric C, each fiber layer C1 is compressed and bonded to one another by embossing. The embossing is performed by passing the nonwoven fabric C through a heated roll heated to a predetermined temperature, thereby fusing the fibers together. The nonwoven fabric according to this embodiment is a thermally bonded nonwoven fabric formed by fusing the fibers together using a heated roll. The embossed area ratio is 5% or more and 25% or less, and more preferably 6% or more and 20% or less. The basis weight of each fiber layer is 10 g / m 2 More than 30g / m 2 Such nonwoven fabric C is suitable as a material for absorbent articles such as diapers and masks.

[0020] Each fiber layer C1 is formed from fibers made from polylactic acid resin. Polylactic acid (PLA) is a biodegradable resin that is hydrolyzed by water in the natural environment to lower molecular weight, and then decomposed by microorganisms into carbon dioxide and water. The nonwoven fabric C according to this embodiment is a biodegradable nonwoven fabric made from polylactic acid.

[0021] The crystallization rate of polylactic acid is slower than that of thermoplastic resins such as polypropylene (PP). When nonwoven fabrics made from polylactic acid are produced using the spunbond method, under the manufacturing conditions for nonwoven fabrics made from polypropylene, the polylactic acid fibers discharged from the nozzle (discharge outlet, spinneret 23 shown in Figure 7) during the spinning process do not crystallize on the conveyor. Furthermore, polylactic acid has low heat resistance when its crystallinity is low, so when fiber layers of polylactic acid with low crystallinity are fused together using a heated roll, the fibers with low heat resistance stick to the heated roll. Furthermore, if polylactic acid has insufficient crystallinity, it will undergo thermal shrinkage when heated, so passing fibers of polylactic acid with low crystallinity through a heated roll will cause thermal shrinkage, resulting in an uneven surface. The glass transition temperature of polylactic acid is approximately 60°C. Generally, when a thermoplastic resin is heated above the glass transition temperature of the fiber by a heated roll while it is not crystallized or has low crystallinity, the fiber sticks to the heated roll. To solve this problem, a nucleating agent (nucleating agent) can be added to the raw material polylactic acid to increase the resin's crystallinity. However, this creates another problem: the nucleating agent remains after the biodegradable nonwoven fabric decomposes. Furthermore, adding a nucleating agent to the raw resin of nonwoven fabric makes it difficult to pull the fibers tightly during the spinning process, resulting in a larger fiber diameter. As the fiber diameter increases, the nonwoven fabric becomes stiffer and uncomfortable against the skin. Nonwoven fabrics that are uncomfortable against the skin are unsuitable for use in absorbent articles or masks.

[0022] Therefore, the inventors of the present invention discovered that the higher the crystallinity of polylactic acid, the higher its heat resistance, and therefore found conditions for increasing the crystallinity of polylactic acid and preventing the polylactic acid fibers from sticking to the heated roll. They also found a tendency that when the fiber diameter of polylactic acid is 15 μm or less, the crystallinity increases and the fibers do not stick to the heated roll (Experimental Example 1). In other words, the inventors discovered that the smaller the fiber diameter of thermoplastic resin fibers, the higher the crystallinity. Polylactic acid has a slower crystallization rate than polypropylene, and under the conditions for producing nonwoven fabrics made from polypropylene, it is believed that the polylactic acid fibers are placed on the conveyor in an amorphous state after the spinning process. In this state, the polylactic acid fibers are heated by the heated roll to approximately the glass transition temperature (60°C) of polylactic acid, causing the fibers to stick to the heated roll.

[0023] Furthermore, the inventors of the present application found that, while the fiber diameter of polypropylene increases when the amount of fiber discharged from the spinneret is increased in the spinning process, the fiber diameter of polylactic acid remains almost unchanged even when the amount of fiber discharged from the spinneret in the spinning process is increased (Experimental Example 2). In other words, even if the amount of fiber discharged from the spinneret in the spinning process changes, the fiber diameter of polylactic acid, which has been thinned to the limit of spinning, remains almost the same.

[0024] The inventors of the present invention also found that polylactic acid fibers tend to become thinner the more they are pulled (Experimental Example 3). Note that Experimental Example 3 was carried out by changing the ejector pressure.

[0025] Furthermore, the inventors of the present invention have found that for polypropylene and polylactic acid, even if the finished fiber diameter is the same, a larger fiber output rate leads to a larger pulling force and a higher degree of crystallinity (Experimental Example 4). This means that the crystallinity increases as the fiber output rate increases.

[0026] FIG. 3 is a table of manufacturing conditions for nonwoven fabrics. In the table of FIG. 3, 12 manufacturing conditions are numbered 1 to 12. The numbers in the "No." column indicate the number assigned to each manufacturing condition. The "+ nucleating agent" in the "raw material" column indicates that a nucleating agent has been added to the polylactic acid. The values ​​in the "output rate (g / min·hole)" column indicate the fiber output rate per minute from the spinneret 23 shown in Figure 7. The values ​​in the "injector pressure (Mpa)" column indicate the pressure of the injector 40 shown in Figure 7. The values ​​in the "diameter (μm)" column indicate the fiber diameter (fiber diameter) after the spinning process. Note that in manufacturing condition No. 7, The fiber diameter was not measured because the phenomenon of fiber breakage (yarn breakage) occurred after the spinning process. The values ​​in the "Crystallization" column indicate the crystallinity of the fiber after the spinning process. In addition, in manufacturing condition No. 7, the phenomenon of fiber breakage (yarn breakage) occurred after the spinning process. ) occurred, so the degree of crystallinity was not measured. The value (145°C) in the "Heat Roll Temperature (°C)" column indicates the surface temperature of the heat roll during the fusion process. The "Stickness" column indicates whether or not the fiber stuck to the heat roll.

[0027] The manufacturing conditions as an example of Experimental Example 1 above are the values ​​shown in the "Diameter" and "Stickness" columns. As shown in the "Diameter" and "Stickness" columns for each manufacturing condition, when the fiber diameter of polylactic acid was 15 μm or less, the crystallinity was 35% or more, and sticking did not occur. On the other hand, when the fiber diameter of polylactic acid was greater than 15 μm, the crystallinity was less than 35, and sticking occurred. For example, the "Diameter" and "Stickness" columns for Nos. 1, 10, and 11 show " column.

[0028] The manufacturing conditions for the above-mentioned Experimental Example 2 are shown in the "Discharge Rate" and "Diameter" columns. As shown in the "Discharge Rate" and "Diameter" columns for each manufacturing condition, the fiber diameter of polylactic acid did not change due to the increased fiber discharge rate from the spinneret during the spinning process. For example, this is shown in the "Discharge Rate" and "Diameter" columns for Nos. 9 and 10.

[0029] The manufacturing conditions for the above-mentioned Experimental Example 3 are shown in the "Injector Pressure" and "Diameter" columns. As shown in the "Injector Pressure" and "Diameter" columns for each manufacturing condition, the more the polylactic acid fiber is pulled, the thinner it becomes. For example, the "Injector Pressure" for No. 9 and No. 10 and as shown in the "Diameter" column.

[0030] The manufacturing conditions for the above-mentioned Experimental Example 4 are shown in the "Injector Pressure" and "Crystallization" columns. As shown in the "Injector Pressure" and "Crystallization" columns for each manufacturing condition, the greater the pulling amount, the higher the crystallinity. For example, in the "Injector Pressure" columns for Nos. 2 and 3, The results are shown in the "Pressure" and "Crystallization" columns.

[0031] As shown in the table in Figure 3, by setting the fiber diameter of polylactic acid to 15 μm or less, the crystallinity of the polylactic acid resin can be made 35% or more. Even if the fiber diameter is greater than 15 μm, the crystallinity can be made 35% or more by adding a nucleating agent to the polylactic acid. By setting the crystallinity of the polylactic acid resin to 35% or more, thermal shrinkage of the polylactic acid fibers can be suppressed during the fusion process.

[0032] The inventors of the present application also discovered that, with thermoplastic resins such as polypropylene, if the surface temperature of the heat roll is set to or above the glass transition temperature of the fibers, the fibers stick to the heat roll, but with polylactic acid resin, if the surface temperature of the heat roll is set to or above 110°C, which is above the glass transition temperature of polylactic acid of 60°C, the fibers of polylactic acid do not stick to the heat roll. This is thought to be because, when the surface temperature of the heat roll is above the glass transition temperature but below 90 to 110°C, the fibers stick to the heat roll without fusing together, but when the surface temperature of the heat roll is 110°C or above, the amount of fibers fusing together increases, so even if some fibers stick to the heat roll, the fibers within the nonwoven fabric will fuse together after passing through the heat roll.

[0033] Figure 4 is a table showing the results of an experiment on the relationship between the surface temperature of a heated roll when polylactic acid fibers are passed through the heated roll and the degree of adhesion to the heated roll. In the "Degree of adhesion" column in the table, "×" is indicated if the degree of adhesion is problematic from a manufacturing perspective, "◯" is indicated if a small amount of fiber adhered to the heated roll but the degree of adhesion is not problematic from a manufacturing perspective, and "◎" is indicated if no fiber adhered to the heated roll at all.

[0034] In the nonwoven fabric manufacturing method according to this embodiment, a nonwoven fabric using a polylactic acid resin as a raw material can be manufactured by setting the surface temperature of the heated roll to 110°C or higher. If the surface temperature of the heated roll is 110°C or higher but lower than 120°C, for example, a release agent can be applied to the heated roll to prevent the fibers from sticking to the heated roll. If the surface temperature of the heated roll is lower than 60°C, the polylactic acid fibers do not fuse together, and the required strength cannot be obtained in the completed nonwoven fabric.

[0035] Preferably, the surface temperature of the heated roll is 120° C. or higher. By setting the surface temperature of the heated roll to 120° C. or higher, it is possible to prevent the fibers from sticking to the heated roll without applying a release agent to the heated roll.

[0036] More preferably, the surface temperature of the heat roll is 145° C. or higher.

[0037] The melting point of polylactic acid fibers is 150° C. or higher. More specifically, the melting point of polylactic acid fibers is about 170° C.

[0038] The inventors of the present invention also discovered that increasing the extrusion rate of polylactic acid fibers allows for a smaller fiber diameter, thereby increasing the crystallinity of the polylactic acid resin. It is presumed that increasing the extrusion rate increases the crystallinity of the polylactic acid resin due to the highly oriented molecules. Therefore, the inventors of the present invention discovered that the crystallinity of polylactic acid can be increased by adjusting the fiber drawing speed. Increasing the extrusion rate increases the fiber speed (yarn speed) even for the same fiber diameter, shortening the fiber drawing time. In the spinning process, increasing the fiber speed shortens the time it takes for the yarn to pass from the spinneret to the ejector. Furthermore, even if the fiber pulling speed is the same at the same drawdown ratio (draw ratio, yarn speed at the ejector / yarn speed at the spinneret), the drawing speed increases. However, because it is difficult to actually measure the speed transition of the fiber during the spinning process, a convenient average speed is calculated by averaging the initial and final yarn speeds, which can be calculated by calculation.

[0039] Here, with reference to FIG. 5, a method for calculating a convenient average fiber velocity in the spinning process will be described. FIG. 5 is a graph showing the fiber velocity in the spinning process. The horizontal axis of FIG. 5 represents the fiber position. In the graph of FIG. 5, the origin is the spinneret position, and the horizontal axis represents the fiber position up to the injector (injector 40 shown in FIG. 7). The vertical axis of FIG. 5 represents the fiber velocity. The fiber velocity at the spinneret is V1, and the fiber velocity at the injector is V2. Line L1 in FIG. 5 represents the change in fiber velocity when the fiber discharge rate is relatively small, and line L2 in FIG. 5 represents the change in fiber velocity when the fiber discharge rate is relatively large. In reality, the fiber velocity changes in a curved line as shown by lines L1 and L2. However, since it is difficult to measure the fiber velocity at each position, a convenient average velocity is calculated by adding the velocities V1 and V2 and dividing the result by 2 using the following equation (1): In the graph of FIG. 5, V1 and V2 represent the fiber velocities when the fiber discharge rate is relatively large, as indicated by line L2. (Number 1) Average speed=(V1+V2) / 2···(1) The fiber passage time is calculated using the following formula (2). (Number 2) Passage time = 2L / (V1+V2) (2) The drawdown ratio (the rate at which the yarn is stretched, the draw ratio) is calculated using the following formula (3). (Number 3) Drawdown rate = V2 / V1 (3) The stretching speed is calculated using the following formula (4). (Number 4) Stretching speed = drawdown rate / passing time = V2 / V1×(V1+V2) / 2L...(4) This drawing speed (1 / min) is used as a parameter. In this embodiment, the drawing speed for drawing the polylactic acid resin in the spinning step is set to 180,000 / min or more.

[0040] In addition, if the fiber diameter is the same, the drawdown rate does not depend on the fiber discharge amount. The down-down ratio is an index of how much the fiber is stretched by the ejector. The larger the amount of polylactic acid fiber ejected, the smaller the fiber diameter, which increases the crystallinity of the polylactic acid, resulting in higher thermal stability and strength of the fiber. As mentioned above, the shorter the stretching time for polylactic acid resin, the more molecular orientation occurs during the stretching process, resulting in a higher crystallinity.

[0041] In this embodiment, by producing a fiber layer using polylactic acid as a raw material under the above conditions, the crystallinity of the resin is increased, and even when this fiber layer is heated with a heated roll, the fibers can be prevented from sticking to the heated roll. Thus, according to this embodiment, a nonwoven fabric using polylactic acid as a raw material can be realized.

[0042] In this embodiment, no nucleating agent is added to the raw material polylactic acid. As a result, the nonwoven fabric according to this embodiment does not contain a nucleating agent. This means that the nonwoven fabric according to this embodiment does not leave behind any nucleating agent after decomposing in nature. Furthermore, if the raw resin contains a nucleating agent, the resin cannot be pulled strongly during the spinning process, resulting in thicker fibers. Furthermore, the use of a nucleating agent increases the manufacturing cost of the nonwoven fabric. However, since the nonwoven fabric according to this embodiment does not contain a nucleating agent, these problems do not occur.

[0043] Next, a method for producing a nonwoven fabric according to this embodiment will be described with reference to FIG. 6. FIG. 6 is a flowchart illustrating the method for producing a nonwoven fabric according to this embodiment. First, in the production method according to this embodiment, molten polylactic acid resin is discharged vertically downward from a die, and the resin is pulled vertically downward by an airflow (step S101, an example of the "spinning process" referred to in this application). In this spinning process, the fiber diameter is set to 15 μmm or less. In step S102, which is the next step after step S101, the fibers are piled up on a conveyor and transported. In step S103, which is the next step after step S102, the three layers of fibers are passed through a heated roll to fuse the fibers together (an example of the "fusing process" referred to in this application).

[0044] Next, a method and apparatus for producing a nonwoven fabric according to this embodiment will be described with reference to FIG. 7. FIG. 7 is a diagram showing a nonwoven fabric production apparatus M for producing a nonwoven fabric according to this embodiment. In FIG. 7, the nonwoven fabric production apparatus M is equipped with three sets of spraying devices (fiber spraying devices) 10, and each of the spraying devices 10 (10A, 10B, 10C) is constructed with a spinning device 20 (an example of the "discharge section" referred to herein), a cooling air device 30 (an example of the "cooling section" referred to herein), and an injector 40 (an example of the "stretching section" referred to herein). The nonwoven fabric production apparatus M is equipped with the spraying devices 10A, 10B, and 10C, and is therefore capable of producing a three-layer nonwoven fabric C.

[0045] In the nonwoven fabric manufacturing apparatus M, together with the ejection device 10, a collecting conveyor 50 (an example of the "sheet conveying device" referred to herein), an embossing device 60 (an example of the "fusion unit" referred to herein), and a winder 70 are arranged in series so that various processes can be performed. The ejection devices 10A, 10B, and 10C are arranged in series in the conveyance direction relative to the conveyance surface above the collecting conveyor 50. The nonwoven fabric manufacturing apparatus M is constructed to continuously produce a nonwoven fabric C whose CD (cross direction) is the direction into the paper surface of FIG. 7, and produces the nonwoven fabric C by a so-called spunbonding method in which spun fibers (filaments) are collected in a sheet form and embossed to appropriately bond the fibers together.

[0046] The spinning device 20 is configured to include an extruder 21 and a spinneret 23. The extruder 21 melts raw material resin R (R1, R2, R3) supplied to a hopper 22, and sends the melt at a predetermined flow rate to the spinneret 23 by the rotation of a spiral rotor 21r. The spinneret 23 has a plurality of composite spinning nozzles (not shown) configured to discharge the melt from the extruder 21 while forming a desired fibrous structure, and spins the melt into a bundle of a plurality of filaments (fibers) f (hereinafter referred to as The filaments are spun (discharged) in the direction of gravity as a filament aggregate F. As for the raw material resin R, a polylactic acid resin is used as described above.

[0047] The cooling air device 30 is equipped with a pair of open-type air blowers 31, 32 arranged in opposing positions. The cooling air device 30 is arranged between the spinning device 20 and the injector 40 when viewed in the spinning direction (gravity direction). The cooling air device 30 cools the filament aggregate F by blowing cooled air Ac from each of the air blowers 31, 32 onto the filament aggregate F that is discharged from the spinning device 20 and passes from above to below. Here, one of the air blowers 31 is installed as a large type that can be used as a main blower, and the other opposite air blower 32 is installed as a small type that can be used as a sub blower and auxiliary. The open-type air blower 30 allows air to flow in from outside the nonwoven fabric manufacturing apparatus M during cooling by the air blower 30.

[0048] The injector 40 (an example of a "drawing device" in the present application) has a structure that generates a low-pressure region on the inlet side of the body 41 by blowing downward-flowing high-pressure air as a driving fluid onto the filament aggregate F that descends through the body 41 from above in the spinning direction. The injector 40 draws the descending filament aggregate F so as to draw it into the low-pressure region on the inlet side of the body 41, while also drawing it downward within the body 41 with high-pressure air, thereby drawing the filament aggregate F that descends from above in the spinning direction via the cooling air device 30. The process from when the polylactic acid resin is discharged from the spinneret 23 of the spinning device 20 until the filament aggregate is deposited on the collection conveyor is step S101 (spinning process) shown in FIG. 6.

[0049] The collecting conveyor 50 is constructed to include a main conveyor 51, sub-conveyors 52 and 53, and a suction box (suction means) 54. The main conveyor 51 is installed so that a mesh-like collecting belt 151, which is formed wider than the width of the filament aggregate F and is breathable on both sides, is wound around a group of rollers 151r and driven to rotate. The sub-conveyors 52 and 53 are also installed so that mesh-like collecting belts 152 and 153, which are formed wider than the width of the filament aggregate F and are breathable on both sides, are wound around a group of rollers 152r and a group of rollers 153r, respectively, and driven to rotate in opposite directions.

[0050] The collecting belt 151 is wound around a group of rollers 151r with a length that ensures that the upper surface 151a is positioned at the spraying points below the spraying devices 10A, 10B, and 10C. The collecting belt 151 receives and transports the filament aggregate Fa that is pulled down by the injector 40 and stretched by the injector 40, thereby collecting the filament aggregate Fa into a cloth (sheet). That is, the collecting belt 151 has a sufficient area to collect the sheet-like filament aggregate Fa and functions as a collecting surface and a conveying surface by rotating from the upstream end (leading edge) to the downstream end (rear edge) in the rotating direction (transport direction) of the upper surface 151a. The filament aggregate Fa forms the lower fiber layer C1 in the nonwoven fabric C shown in FIG. 2.

[0051] The collecting belt 152 is wound around a group of rollers 152r with its upper surface 152a positioned at a spraying point below the jetting device 10B, which is located midway in the circumferential movement direction of the upper surface 151a of the collecting belt 151. The collecting belt 152 receives and transports the filament aggregate Fb that is pulled down by the injector 40, thereby collecting it in sheet form. The collecting belt 153 is wound around a group of rollers 153r with its upper surface 153a positioned at a spraying point below the jetting device 10C, which is located at the downstream end (rearmost rear) of the circumferential movement direction of the upper surface 151a of the collecting belt 151. The collecting belt 153 receives and transports the filament aggregate Fc that is pulled down by the injector 40, thereby collecting it in sheet form. The filament aggregate Fb becomes the middle fiber layer C1 in the nonwoven fabric C shown in FIG. 2.

[0052] These collecting belts 152, 153 are installed downstream from below the jetting device 10A, which is located at the upstream end (head) of the circulating direction of the upper surface 151a of the collecting belt 151, and are driven to rotate in the reverse direction while positioned between the upper surface 151a and the jetting devices 10B, 10C, so that their upper surfaces 152a, 153a function as a collecting surface and a conveying surface for collecting the sheet-like filament assemblies Fb, Fc. The collecting belts 152, 153 are driven to rotate between their lower parts facing the upper surface (upper part) 151a of the collecting belt 151 so as to sandwich the sheet-like filament assemblies Fb, Fc without peeling or turning over, thereby assisting in the conveyance downstream.

[0053] The suction box 54 is housed within the collecting belt 151 of the main conveyor 51 and is divided into suction chambers 154a, 154a-2, 154b, 154b-2, 154c, and 154c-2, each functioning as a decompression chamber. Suction ports (not shown) are arranged in the suction chambers 154a to 154c-2 so as to suck the upper sides, and suction fans 155a to 155c-2, which can be driven individually, are connected to enable suction.

[0054] The suction chambers 154a, 154b, and 154c are installed so as to be located below the injectors 40 of the ejection devices 10A, 10B, and 10C, respectively, and the suction chambers 154a-2, 154b-2, and 154c-2 are installed so as to be located downstream of these suction chambers 154a, 154b, and 154c.

[0055] The suction chamber 154a is installed so as to be located directly below the collection belt 151 of the main conveyor 51 below the injector 40 of the ejection device 10A, and when the suction fan 155a is driven to reduce the pressure, it sucks in the area from directly below the collection belt 151 upward.

[0056] The suction chamber 154a-2 is located adjacent to the downstream side of the suction chamber 154a and is positioned directly below the collection belt 151 of the main conveyor 51 between it and the suction chamber 154b located below the ejection device 10B, as described below.The suction fan 155a-2 is driven to reduce the pressure, thereby sucking in the area above the collection belt 151.

[0057] As a result, the filament aggregate Fa spun by the jetting device 10A is sucked by the suction chamber 154a below the collecting belt 151 of the main conveyor 51 so as to be collected on the upper surface 151a. As the collecting belt 151 moves around in the length direction, the filament aggregate Fa is collected in a sheet-like form on the upper surface 151a and held thereon for transport. Thereafter, as the collecting belt 151 moves around in the length direction, the filament aggregate Fa is passed from the suction chamber 154a to the adjacent suction chamber 154a-2, where it is sucked and held thereon so as to maintain its sheet shape and is transported.

[0058] The suction chamber 154b is installed so as to be located directly below the collection belt 151 of the main conveyor 51 below the injector 40 of the ejection device 10B, and when the suction fan 155b is driven to reduce the pressure, it sucks in the area directly below the collection belt 151 and above the collection belt 152 of the sub-conveyor 52.

[0059] The suction chamber 154b-2 is located adjacent to the downstream side of the suction chamber 154b and is positioned directly below the collection belt 151 of the main conveyor 51 between it and the suction chamber 154c located below the ejection device 10C, as described below.The suction fan 155b-2 is driven to reduce the pressure, thereby sucking in the area above the collection belt 151.

[0060] As a result, the filament aggregate Fa spun by the ejection device 10A is sucked and held in sheet form on the upper surface 151a by the suction chambers 154b and 154b-2 below the collecting belt 151 of the main conveyor 51, following the suction chambers 154a and 154a-2. will be sent.

[0061] Furthermore, the filament aggregate Fb spun by the jetting device 10B is sucked by the suction chamber 154b below the collecting belt 151 of the main conveyor 51 so as to be collected on the upper surface 152a of the collecting belt 152 of the sub-conveyor 52 on the upper surface 151a. Therefore, the filament aggregate Fb is collected and held in a sheet-like form on the upper surface 152a as the collecting belt 152 moves around in the longitudinal direction.

[0062] Incidentally, the collecting belt 152 of the sub-conveyor 52 rotates in the opposite direction to the collecting belt 151 of the main conveyor 51, and therefore the upper surface 152a of the collecting belt 152 moves in the opposite direction, and then is turned upside down and moves in the same direction facing the upper surface 151a of the collecting belt 151 of the main conveyor 51. Therefore, the filament aggregate Fb spun by the jetting device 10B is collected and held in a sheet-like form on the upper surface 152a of the collecting belt 152 of the sub-conveyor 52 and transferred, and then overlaps the sheet-like filament aggregate Fa on the upper surface 151a of the collecting belt 151 of the main conveyor 51, and is suction-held in the sheet-like form by the suction chamber 154b below the collecting belt 151 of the main conveyor 51 and transferred.

[0063] As a result, the filament aggregate Fab (Fa, Fb) that is collected, held, and stacked in a sheet form below the ejection device 10B is transferred from the suction chamber 154b to the adjacent suction chamber 154b-2 as the collection belt 151 moves around in the longitudinal direction, where it is suction-held and transported so as to maintain its sheet shape.

[0064] The suction chamber 154c is installed so as to be located directly below the collection belt 151 of the main conveyor 51 below the injector 40 of the ejection device 10C, and when the suction fan 155c is driven to reduce the pressure, it sucks in the area directly below the collection belt 151 and above the collection belt 153 of the sub-conveyor 53.

[0065] The suction chamber 154c-2 is installed adjacent to the downstream side of the suction chamber 154c, as described below, so as to be located just below the end of the collection belt 151 of the main conveyor 51, and when the suction fan 155c-2 is driven to reduce the pressure, it sucks in the area from just below the collection belt 151 upward.

[0066] As a result, the filament aggregates Fab spun by the ejection devices 10A and 10B are transported by the suction chambers 154a to 154b-2 described above, followed by the suction chambers 154c and 154c-2 below the collecting belt 151 of the main conveyor 51, where they are suction-held in sheet form overlapping on the upper surface 151a.

[0067] The filament aggregate Fc spun by the jetting device 10C is sucked by the suction chamber 154c below the collecting belt 151 of the main conveyor 51 so as to be collected on the upper surface 153a of the collecting belt 153 of the sub-conveyor 53 on the upper surface 151a. As a result, the filament aggregate Fc is collected in a sheet-like form on the upper surface 153a and held and transported as the collecting belt 153 moves around in the longitudinal direction. The filament aggregate Fc becomes the upper fiber layer C1 of the nonwoven fabric C shown in FIG. 2.

[0068] Incidentally, the collecting belt 153 of the sub-conveyor 53 also rotates in the opposite direction to the collecting belt 151 of the main conveyor 51, so that the upper surface 153a of the collecting belt 153 moves in the opposite direction and then is turned upside down to face the upper surface 151a of the collecting belt 151 of the main conveyor 51 and move in the same direction. For this reason, the filament aggregate Fc spun by the ejection device 10C is spun on the upper surface 153a of the collecting belt 153 of the sub-conveyor 53. After being collected and held in a sheet-like form and transported, it is further overlapped on the sheet-like filament aggregate Fab on the upper surface 151a of the collecting belt 151 of the main conveyor 51, and is then sucked and held in sheet form by the suction chamber 154c below the collecting belt 151 of the main conveyor 51 and transported.

[0069] As a result, the filament aggregate Fabc (Fa, Fb, Fc) that is collected, held, and stacked in a sheet form below the ejection device 10C is transferred from the suction chamber 154c to the adjacent suction chamber 154c-2 as the collection belt 151 moves around in the longitudinal direction, where it is suction-held and transported so as to maintain its sheet shape.

[0070] In short, the collecting conveyor 50 collects and holds the filament assemblies Fa, Fb, and Fc spun by the spraying devices 10A, 10B, and 10C on the upper surfaces 151a to 153a of the collecting belts 151 to 153 by suction using the suction boxes 54 in the form of a sheet of a predetermined thickness, and then stacks them to form the pre-embossed filament assembly FaC (nonwoven fabric C), which is then transported downstream to the embossing device 60. The process in which the filament assemblies are deposited on the collecting conveyor and transported is step S102 shown in FIG.

[0071] The embossing device 60 includes a pair of embossing rolls (heated rolls) 61, 62, which rotate relative to one another with their cylindrical outer circumferential surfaces 61a, 62a pressed against each other. In the embossing device 60, embossing protrusions (not shown) arranged regularly or irregularly on the cylindrical outer circumferential surface 62a of the upper embossing roll 62 are pressed against the smooth cylindrical outer circumferential surface 61a of the lower embossing roll 61 with a desired pressure. The embossed area ratio may be 5% or more and 25% or less.

[0072] As a result, the embossing device 60 feeds the filament aggregate Fbc sandwiched between the embossing rolls 61 and 62 (an example of a heated roll) in the direction of relative rotation, and performs embossing at multiple embossing locations corresponding to the positions of the embossing protrusions, thereby entangling and compressing and bonding the filaments f, thereby processing the filaments f into a nonwoven fabric C that maintains its sheet-like shape. Note that the embossing protrusions formed on the cylindrical outer peripheral surface 62a of the embossing roll 62 may be formed on the cylindrical outer peripheral surface 61a of the embossing roll 61, or may be formed on both the cylindrical outer peripheral surfaces 61a, 62a of the embossing roll 61. Furthermore, the embossing protrusions are not limited to a convex shape, and may be formed in a concave shape so that, for example, a continuous rib shape is pressed against the opposing cylindrical surface for compression bonding. Note that the embossing of the filament aggregate Fbc by the embossing device 60 corresponds to step S103 (fusion process) shown in FIG. 6. The surface temperature of the embossing rolls 61, 62 is 110° C. or higher, preferably 110° C. or higher, and more preferably 145° C. or higher. By setting the surface temperature of the embossing rolls 61, 62 to 120° C. or higher, it is possible to prevent the fibers from sticking to the embossing rolls 61, 62 even if a release agent is not applied to the embossing rolls 61, 62.

[0073] The winder 70 receives the nonwoven fabric C in which the filaments f of the filament aggregate Fbc are intertwined and bonded by the embossing device 60 while adjusting the tension so as not to cause slack, and continuously winds the nonwoven fabric C into a roll without wrinkles and with the desired winding hardness.

[0074] As a result, the winder 70 can prepare the nonwoven fabric C of a desired length, in which the filament aggregate Fbc is formed into a sheet and wound into a roll, so that it can be supplied to the next processing step or the like.

[0075] As described above, the collecting conveyor 50 of this embodiment is configured such that the suction chambers 154a to 154c-2 of the suction box 54 installed under the collecting belt 151 of the main conveyor 51 correspond to the injectors 40 of the ejection devices 10A to 10C. The suction fans 155a to 155c-2 connected to the suction chambers 154a to 154c-2 are set to suck at a wind speed (air volume) according to the partitioned range (area) of the suction chambers 154a to 154c-2 and the required suction pressure. Here, the partitioned range to be sucked and the suction pressure of the suction chambers 154a to 154c-2 may be set appropriately.

[0076] Specifically, the suction chamber 154a sucks the filament aggregate Fa, which is pulled down from the outlet of the injector 40 of the ejection device 10A directly above the collection belt 151 of the main conveyor 51, from below the collection belt 151 without the need for a sub-conveyor, and collects and holds it in a sheet form.

[0077] This suction chamber 154a is partitioned so that a suction pressure Pa capable of stably holding the descending filament aggregate Fa is generated under the conveying surface of the collection belt 151 in a narrow range approximately equal to the spray area in the transport direction, and the interior of this partitioned range is suctioned by a suction fan 155a to create a negative pressure.

[0078] The suction chambers 154b and 154c respectively suck the filament assemblies Fb and Fc that are pulled down from the outlets of the injectors 40 of the ejection devices 10B and 10C directly above the collecting belts 152 and 153 of the sub-conveyors 52 and 53 from below the collecting belt 151, and collect and hold them in a sheet form. These sub-conveyors 52 and 53 sandwich the sheet-like filament assemblies Fb and Fc that are collected and held on the collecting belts 152 and 153 between themselves and the lower collecting belt 151, and send them downstream as filament assemblies Fab and Fabc.

[0079] These suction chambers 154b, 154c are driven by suction fans 155b, 155c to create negative pressure so as to generate suction pressures Pb, Pc below the conveying surfaces of the collecting belts 152, 153, sufficient to stably hold the descending filament assemblies Fb, Fc. Similar to the suction chamber 154a, these suction chambers 154b, 154c are also suctioned and created negative pressure by the suction fans 155b, 155c so as to generate the desired suction pressures Pb, Pc in a narrow, compartmented range approximately equal to the spray area in the conveying direction of the descending filament assemblies Fb, Fc. At the same time, these suction chambers 154b, 154c apply suction to the collecting belts 152, 153 of the sub-conveyors 52, 53, with the filament assemblies Fab, Fabc on the collecting belt 151 interposed therebetween. For this reason, these suction chambers 154b, 154c may increase or decrease the suction volume by adjusting the suction range in the transport direction below the collection belt 151 so that optimal suction pressures Pb, Pc are generated on the collection belts 152, 153, and the suction range within the collection belts 152, 153 may also be similarly divided into adjustable sections.

[0080] As a result, the suction chambers 154b and 154c, like the suction chamber 154a, can continuously suck and hold the filament assemblies Fab and Fabc that are increased from the sheet-like filament assembly Fa via the collection belt 151 of the main conveyor 51.

[0081] The suction chambers 154a-2, 154b-2, and 154c-2 continuously suck and hold the sheet-like filament assemblies Fa, Fab, and Fabc on the collection belt 151 of the main conveyor 51 downstream of the suction chambers 154a, 154b, and 154c, respectively.

[0082] These suction chambers 154a-2, 154b-2, and 154c-2 are driven by suction fans 155a-2 to generate suction pressures Pa-2, Pb-2, and Pc-2 that continuously suck and hold the sheet-like filament assemblies Fa, Fab, and Fabc on the collection belt 151. Note that the suction chambers 154a-2 and 154b-2 are interposed between the suction chambers 154a, 154b, and 154c and are continuous so as to suck without gaps, so that a wide partition area is formed so as to connect the separate collection positions of each ejection device 10. In addition, the suction chamber 154c-2 is installed to suck a relatively short section range because it simply delivers the sheet-shaped filament aggregate FBC received from the suction chamber 154c to the adjacent embossing device 60 downstream.

[0083] As a result, the suction chambers 154a-2, 154b-2, and 154c-2 can suck and hold the sheet-like filament assemblies Fa, Fab, and Fabc located on the upper surface 151a via the collecting belt 151 of the main conveyor 51, successively to the suction chambers 154a, 154b, and 154c, respectively. At this time, the sheet-like filament assemblies Fa and Fab on the collecting belt 151 of the main conveyor 51 are sucked and held by the suction chambers 154a-2 and 154b-2, respectively, and therefore do not float up, but are sandwiched between the collecting belts 152 and 153 of the sub-conveyors 52 and 53. Furthermore, the sheet-like filament assemblies Fa and Fab are superimposed on the sheet-like filament assemblies Fb and Fc that are collected and held by the collecting belts 152 and 153 and are turned upside down, forming sheet-like filament assemblies Fab and Fabc, which are then transported downstream while being sucked and held.

[0084] As described above, the collecting conveyor 50 is configured so that the individual suction fans 155a to 155c-2 suck at the required air speed so that a suction pressure P sufficient to collect and hold the sheet-like filament aggregate F on the collecting belt 151 of the main conveyor 51 is generated in each of the suction chambers 154a to 154c-2 of the suction box 54. Note that the relative relationship (strength) of the suction pressure P on the collecting surface (transport surface) of the filament aggregate F in each of the suction chambers 154a to 154c-2, which will be described below, will be explained by calculating and substituting an air speed value corresponding to the separation space from the connecting point of the suction fans 155a to 155c-2 to the collecting surface.

[0085] For example, the suction box 54 is adjusted so that the suction pressures Pa, Pb, and Pc of the suction chambers 154a, 154b, and 154c located at the points where the filament aggregate F is sprayed by the spraying devices 10A, 10B, and 10C on the collection conveyor 50 are greater than the suction pressures Pa-2, Pb-2, and Pc-2 of the suction chambers 154a-2, 154b-2, and 154c-2 located downstream of each other. Furthermore, among these, the suction pressures Ps (Pa, Pa-2) of the leading suction chambers 154a, 154a-2 in the transport direction of the filament aggregate F, Pm (Pb, Pb-2) of the intermediate suction chambers 154b, 154b-2, and Pe (Pc, Pc-2) of the rearmost suction chambers 154c, 154c-2 are suction-held on both the upstream and downstream sides, so the suction pressure Pm at the intermediate position can be adjusted to be smaller than the leading suction pressure Ps and the rearmost suction pressure Pe (Ps > Pm and Pe > Pm). Furthermore, the suction pressures Pa, Pb, and Pc are adjusted according to the weight of the filament aggregate F on the transport surface so as not to excessively reduce the pressure inside the suction chambers 154a, 154b, and 154c, thereby preventing smooth relative movement of the collecting belt 151.

[0086] In detail, the suction chamber 154a is configured to set the suction pressure Pa in the collection belt 151 of the main conveyor 51, which collects and holds the filament aggregate Fa spun by the ejection device 10A in a sheet form, to a value, for example, of 10 to 30 g / m2 when the basis weight of the semi-finished product to be wound into a roll by the winder 70 is 10 to 30 g / m2. 2 When producing the nonwoven fabric C, the air speed Pa is set to 7.5. This suction pressure (air speed) Pa is set to a relatively strong value so that the filament aggregate Fa is attracted to the upper surface 151a of the collecting belt 151 regardless of its basis weight, because this is the point where the filament aggregate Fa is sucked in and begins to be collected and held in a sheet form.

[0087] The suction chamber 154a-2 is connected to the suction chamber 154a in the same manner as the suction chamber 154a, and is configured to have a suction pressure Pa-2 and a basis weight of 10 to 30 g / m. 2 When producing nonwoven fabric C, the air velocity Pa-2 is set to 3.8. Here, the suction pressure (air velocity) Pa-2 is As with Pa, regardless of the basis weight (weighing) of the filament aggregate Fa, it is sufficient that it maintains its shape so that it can be sucked and held in a sheet-like form, and since it is sandwiched as is between the collection belts 151 and 152 of the main conveyor 51 and sub-conveyor 52, the suction pressure is kept low, about half that of Pa.

[0088] The suction chamber 154b is configured to have a suction pressure Pb of, for example, 10 to 30 g / m 2 When producing the nonwoven fabric C, the wind speed Pb is set to 6.0. Like the suction pressure Pa, the suction pressure (wind speed) Pb is set to a strong value regardless of the basis weight because the filament aggregate Fb is collected and formed into a sheet on the collecting belt 152 of the sub-conveyor 52. However, because the filament aggregate Fab on the collecting belt 151 of the main conveyor 51 is sucked in between, the wind speed Pb is kept low so as not to restrict the movement of the collecting belt 151.

[0089] The suction chamber 154b-2 is connected to the suction chamber 154b and has a suction pressure Pb-2 and a basis weight of 10 to 30 g / m 2When producing the nonwoven fabric C, the air velocity Pa is set to 3.2. Here, like the suction pressure Pb, the suction pressure (air velocity) Pb-2 is sufficient to maintain the sheet-like shape of the filament aggregates Fb and Fab, regardless of their basis weight (grams). Since the filament aggregates Fb and Fab are sandwiched between the collecting belts 151 and 153 of the main conveyor 51 and the sub-conveyor 53, the suction pressure (air velocity) Pb-2 is set to an extremely low value, and is set so that the filament aggregates F with a lower basis weight are more strongly suctioned so that they are reliably suctioned and enter between the collecting belts 151 and 153. Note that, on the collecting belt 151 of the main conveyor 51 below the sub-conveyor 53, the sheet-like filament aggregate Fc collected and held by the collecting belt 153 is sandwiched in a state overlapping the sheet-like filament aggregate Fab, held by suction, and transported downstream.

[0090] The suction chamber 154c is configured to have a suction pressure Pc of, for example, 10 to 30 g / m 2 When producing nonwoven fabric C, the suction pressure (wind speed) Pc is set to Pa = 7.4. Like the suction pressures Pa and Pb, the suction pressure (wind speed) Pc is set to a strong value regardless of the basis weight because the filament aggregate Fc is collected and formed on the collecting belt 153 of the sub-conveyor 53, but because the filament aggregate Fc on the collecting belt 151 of the main conveyor 51 is sucked in between, the suction pressure is kept low so as not to restrict the movement of the collecting belt 151.

[0091] The suction chamber 154c-2 is connected to the suction chamber 154c and has a suction pressure Pb-2, for example, a basis weight of 10 to 30 g / m 2 When producing the nonwoven fabric C, the suction pressure (wind speed) Pc-2 is set to Pa=3.2 to 3.8. The suction pressure (wind speed) Pc-2 is set lower than the suction pressure Pa depending on the basis weight so that the filament aggregate FBC carried out from under the sub-conveyor 53 is reliably sucked and held by the collecting belt 151 of the main conveyor 51 and delivered to the embossing device 60.

[0092] In the nonwoven fabric manufacturing apparatus M, the line speed of the collecting belts 151, 152, and 153 is 40 m / min or more and 120 m / min or less. min The fiber discharge rate of the ejection devices 10A, 10B, and 10C is 0.5 g / min / hole (0.5 g / min hole) or less. The filament aggregates Fa, Fb, and Fc (fiber layer C1) are produced at a spinning speed of 10 to 150 m / s. In the nonwoven fabric C produced under these conditions, the fiber diameter in the fiber layer C1 is 15 μm or less. The spinning speed can be adjusted by the injection pressure of the ejection devices 10A, 10B, and 10C.

[0093] By the manufacturing method described above, a nonwoven fabric made from a polylactic acid resin can be manufactured. Although the raw material is polylactic acid, the nonwoven fabric may contain monomers other than polylactic acid. They may be mixed within a range that does not impair the light-emitting effect. Lactic acid exists as optical isomers, L-lactic acid and D-lactic acid, and the raw material used in this embodiment is polylactic acid, which is a polymer of L-lactic acid. In the polylactic acid used as the raw material, the proportion of D-lactic acid is preferably 1% or less.

[0094] <Other embodiments> The above describes the embodiments of the present invention, but the various embodiments described above can be combined as much as possible. While the above embodiments use a spunbonded nonwoven fabric as an example, the present invention is not limited to this. For example, the present invention can also be applied to spunbonded nonwoven fabrics, thermally bonded nonwoven fabrics, chemically bonded nonwoven fabrics, needle-punched nonwoven fabrics, and stitch-bonded nonwoven fabrics. [Explanation of symbols]

[0095] C··Non-woven fabric C1 Fiber layer M··Nonwoven fabric manufacturing equipment 10, 10A, 10B, 10C...Ejection device 20. Spinning equipment 30·Cold air device 40··Injector 50··Collection conveyor 51 Main conveyor 52, 53 Sub-conveyor 54··Suction box 60··Embossing device 70··Winder 141, 142 Signboard 151, 152, 153 Collection belt 154a, 154b, 154c··Suction chamber 162 Adjustment roller f··filament fr··Rotation diameter F, Fa, Fab, Fabc, Fb, Fc filament assembly Lc Intersection distance Ld...Open interval Lr Evacuation interval P, Pa, Pb, Pc, Pe, Pm, Ps... Suction pressure (wind speed)

Claims

1. A nonwoven fabric manufacturing apparatus for manufacturing a nonwoven fabric made from a polylactic acid-based resin, a discharge unit that melts and discharges the polylactic acid-based resin; a stretching section that stretches the polylactic acid resin by airflow; a cooling unit disposed between the discharge unit and the stretching unit, which blows cooling air onto the polylactic acid-based resin; a sheet conveying section that collects the fibers of the polylactic acid-based resin stretched by the stretching section on a conveying surface to form a sheet-shaped nonwoven fabric and conveys it in a transfer direction; a fusion section that heats the fibers of the polylactic acid-based resin to fuse the fibers together; Equipped with The stretching speed at which the stretching unit stretches the polylactic acid resin is 180,000 / min or more, The extension portion is The fiber speed in the discharge section is V1, the fiber speed in the stretching section is V2, and the average fiber speed from the discharge section to the stretching section is calculated using the following (Equation 1): Average speed = (V1+V2) / 2 (formula 1) The distance from the discharge section to the drawing section is defined as L, and the transit time of the fiber from the discharge section to the drawing section is calculated using the following (Equation 2): Passage time = 2L / (V1+V2) (Formula 2) The drawdown ratio, which is the ratio at which the fiber is stretched, is calculated using the following (Equation 3): Drawdown rate = V2 / V1 (Equation 3) Stretching speed=drawdown rate / passing time=V2 / V1×(V1+V2) / 2L (formula 4), V2 is adjusted by adjusting the high-pressure air so that the drawing speed when the fiber is drawn by blowing high-pressure air and drawing the fiber into a low-pressure region generated by the blowing of the high-pressure air becomes the drawing speed calculated using (Equation 4). Nonwoven fabric manufacturing equipment.

2. the discharge part has a nozzle for discharging the polylactic acid-based resin, The amount of the polylactic acid resin discharged from the die is 0.5 g / min / hole or less. Ru, The nonwoven fabric manufacturing apparatus according to claim 1 .

3. the fusion unit has a heat roll that heats the polylactic acid-based resin fibers, The surface temperature of the heat roll is 110°C or higher. The nonwoven fabric manufacturing apparatus according to claim 1 or 2.

4. The surface temperature of the heat roll is 145°C or higher. The nonwoven fabric manufacturing apparatus according to claim 3.

5. The fused portion is formed by embossing the fibers, The area ratio of the embossing is 5% or more and 25% or less. The nonwoven fabric manufacturing apparatus according to any one of claims 1 to 4.

6. a conveying speed at which the sheet conveying unit conveys the polylactic acid resin fibers is 40 m / min or more and 120 m / min or less; The nonwoven fabric manufacturing apparatus according to any one of claims 1 to 5.

7. Air can flow into the cooling section from the outside. The nonwoven fabric manufacturing apparatus according to any one of claims 1 to 6.

8. the discharge unit spins out a filament aggregate of the polylactic acid-based resin. The nonwoven fabric manufacturing apparatus according to any one of claims 1 to 7.

9. A method for producing a nonwoven fabric using a polylactic acid resin as a raw material, comprising: melting and discharging the polylactic acid-based resin; stretching the polylactic acid resin by an air flow; cooling the polylactic acid resin by blowing cooling air onto the polylactic acid resin while the polylactic acid resin is being stretched by the air flow after being discharged; the stretched polylactic acid resin fibers are collected on a conveying surface to form a sheet-like nonwoven fabric, and conveyed in a conveying direction; the fibers of the polylactic acid resin are heated to fuse the fibers together; Including, The stretching speed of the polylactic acid resin is 180,000 / min or more, The stretching speed is The fiber speed at which the polylactic acid resin is discharged from the discharge section is defined as V1, and the fiber speed at which the polylactic acid resin is stretched in the stretching section is defined as V2. The average fiber speed of V1 and V2 is calculated using the following (Equation 1): Average speed = (V1+V2) / 2 (formula 1) The distance from the discharge section to the drawing section is defined as L, and the transit time of the fiber from the discharge section to the drawing section is calculated using the following (Equation 2): Passage time = 2L / (V1+V2) (Formula 2) The drawdown ratio, which is the ratio at which the fiber is stretched, is calculated using the following (Equation 3): Drawdown rate = V2 / V1 (Equation 3) Stretching speed=drawdown rate / passing time=V2 / V1×(V1+V2) / 2L (formula 4), V2 is adjusted by adjusting the high-pressure air so that the drawing speed when the fiber is drawn by blowing high-pressure air and drawing the fiber into a low-pressure region generated by the blowing of the high-pressure air becomes the drawing speed using (Equation 4). Method for manufacturing nonwoven fabric.

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