CN117500963B - Nonwoven fabric manufacturing device and manufacturing method - Google Patents

Abstract

The present invention provides a device and a method for producing a nonwoven fabric, which can efficiently obtain a nonwoven fabric of ultrafine fibers having very small fiber diameters. The device for producing a nonwoven fabric is provided with a slit-shaped gap (4) between a spinneret plate (1) having a discharge hole group for discharging a molten polymer (2) arranged in a row and a pair of die lips (3) arranged so as to face each other with the discharge hole group of the spinneret plate (1) interposed therebetween, and a polymer blowing gas discharged from the gap (4) to the discharge hole (2), and is characterized in that a pair of widened wall surfaces (6) extending in the polymer discharge direction are arranged so as to face each other with the lower surface of the die lips (3) interposed therebetween, the angle alpha formed by the pair of widened wall surfaces (6) is in the range of 60 DEG to 120 DEG, and the intersection point (X) of the lower surface of the die lips (3) and the wall surface forming the gap (4) is set to be the intersection point (X), and the intersection point (Y) of the lower surface of the die lips (3) and the widened wall surface (6) is set to be the opposite to each other in the range of equal to or less than 15H and the opposite interval (Y) is set to the intersection point (Y) between the intersection point (Y) and the intersection point (Y) of the intersection point (Y) and the intersection point (H).

Description

Apparatus and method for producing nonwoven fabric

Technical Field

The present invention relates to an apparatus and a method suitable for producing nonwoven fabrics by a melt-blown method.

Background

One of the methods for producing nonwoven fabrics is a melt-blowing method in which a high-speed and high-temperature gas stream is blown onto a polymer discharged from a spinneret of a spinneret die (japanese: kou jin), whereby the polymer is melt-bonded while being drawn to form a web, and the web is collected on a web conveyor to obtain a nonwoven fabric. The spinneret die used in the melt-blowing method has a spinneret plate having a group of discharge holes arranged in 1 row in the width direction, and a pair of die lips arranged so as to face each other across the group of discharge holes on both sides of the spinneret plate, with a gap formed between the spinneret plate and the die lips. Further, by blowing high-temperature air from the gap to the polymer discharged from the discharge hole of the spinneret at a high speed under high pressure, a nonwoven fabric including ultrafine fibers can be produced. In recent years, in the gradual expansion of the nonwoven fabric into various applications, a nonwoven fabric having a very small fiber diameter has been demanded as a gradual expansion for high-performance applications such as filters, medical masks, and medical gowns (medical gown).

In such a case, various improvements have been made as means for reducing the fiber diameter of the nonwoven fabric. For reducing the fiber diameter, for example, a method of reducing the amount of polymer discharged from one discharge hole of a spinning die is mentioned, but in this case, there is a problem that the throughput is lowered. Further, if the discharge amount of the polymer is reduced, the discharge may be unstable. Accordingly, patent document 1 discloses a melt-blown yarn die in which the flow path width of hot air ejected from a slit (ejection hole) to a molten polymer is minimized after the point where the hot air merges with the polymer at the lower end of the slit, and then gradually expands. Accordingly, the hot air reaches the sonic velocity at the position of the minimum flow path width, and then the hot air is slowly thermally insulated and expanded, whereby the fiber diameter can be reduced efficiently.

Prior art literature

Patent literature

Patent document 1 Japanese patent laid-open No. 51-67411

Disclosure of Invention

Problems to be solved by the invention

However, the melt-blown filament die disclosed in patent document 1 is formed in a shape in which a flow path of hot air emitted from a slit is once contracted after the polymer is emitted, and then gradually widened. Therefore, the jet flows obliquely against the mesh conveyor of the collection mesh along the wall surface of one side due to Coanda Effect. As a result, the fibers may fly above the mesh conveyor like feathers, and it is difficult to form a mesh. In addition, the polymer discharged from the spinneret is likely to adhere to the flow constriction and the flow widening of the flow path, and shot (polymer lump) may occur, which may make continuous production difficult. Further, since the flow path width is locally extremely narrow, the pressure loss is high, and hence the performance of the compressor device for supplying hot air is necessarily required to be improved, and the equipment cost may be high. In addition, in the melt-blown filament die, the effect of reducing the fiber diameter may be obtained by increasing the supply pressure of the hot air to be supplied, but the use cost is high because the air is used.

Accordingly, an object of the present invention is to provide an apparatus and a method for producing a nonwoven fabric, which can efficiently obtain a nonwoven fabric of ultrafine fibers having very small fiber diameters.

Means for solving the problems

The present invention for solving the above problems adopts any one of the following configurations.

(1) A nonwoven fabric manufacturing apparatus having a slit-shaped gap between a spinneret plate having a discharge hole group in which discharge holes for discharging a molten polymer are arranged in 1 row and a pair of die lips arranged so as to face each other with the discharge hole group of the spinneret plate interposed therebetween, wherein the apparatus is configured to blow a gas from the gap to the polymer discharged from the discharge holes to manufacture a nonwoven fabric,

A pair of widened 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 with the polymer ejected from the ejection hole interposed therebetween,

The pair of widened wall surfaces form an angle alpha in the range of 60 DEG≤alpha≤120 DEG, and

When the intersection point of the lower surface of the die lip and the wall surface forming the gap is X and the intersection point of the lower surface of the die lip and the widened wall surface is Y, the interval P between the opposing intersection points X and the interval H between the opposing intersection points Y are in the range of 2≤H/P≤15.

(2) The apparatus for producing a nonwoven fabric according to the above (1), wherein the angle β between the lower surface of the die lip and the polymer discharge direction is 70℃or more and 120℃or less.

(3) The apparatus for producing a nonwoven fabric according to the above (1) or (2), wherein the length γ of the widened wall surface in the polymer ejection direction is 10mm or more.

(4) The apparatus for producing a nonwoven fabric according to any one of the above (1) to (3), wherein the widened wall surface is movable in a direction intersecting the polymer ejection direction.

(5) The apparatus for producing a nonwoven fabric according to any one of the above (1) to (4), wherein the arithmetic average roughness Ra of the widened wall surface is 100 μm or less.

(6) The apparatus for producing a nonwoven fabric according to any one of the above (1) to (5), which comprises the heating means for widening the wall surface.

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

In the present invention, the "lower surface of the die lip" means a surface of the die lip facing the downstream side in the polymer ejection direction.

In the present invention, the "slit-shaped gap" refers to a rectangular gap which is arranged substantially parallel to the ejection hole groups arranged in 1 row and has a longer cross section in one direction.

In the present invention, the "angle α formed by the pair of widened wall surfaces" is an angle formed by an extension line of a substantially planar wall surface toward the upstream side in the polymer ejection direction as shown in fig. 1, but for example, an angle formed by an extension line of a pair of planar portions is used in the case of a widened wall surface having a portion where the widening angle changes together with the planar portions in the polymer ejection direction, such as in the case where the pair of planar wall surfaces has an R portion on the die lip side.

The term "intersection of the lower surface of the die lip and the wall surface forming the gap" also means substantially the intersection of two planes, but when the position corresponding to the intersection is formed by the R portion, the intersection of the extension lines of the respective planes is adopted. Further, the "intersection point of the lower surface of the die lip and the widened wall" means an intersection point of a substantially planar widened wall and the lower surface of the die lip, but when the position corresponding to the intersection point is formed by the R portion, an intersection point of extension lines of the respective planes is adopted.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, by controlling the jet flow directly under the spinneret die, it is possible to prevent the occurrence of defects such as shot blast and to stably produce a nonwoven fabric of ultrafine fibers.

Drawings

FIG. 1 is a schematic cross-sectional view showing one embodiment of a melt-blown filament die in the present invention.

FIG. 2A schematic cross-sectional view of a melt-blown filament die in the prior art.

Fig. 3 is a schematic side view showing an embodiment of the apparatus for producing a nonwoven fabric according to the present invention.

Fig. 4 is a schematic view showing the direction of air flow immediately below a melt-blown filament die in the prior art.

Fig. 5 is a schematic view showing the direction of air flow directly under the melt-blown filament die in the present invention.

Fig. 6 is a schematic view showing the direction of air flow immediately below a melt-blown filament die in the prior art.

FIG. 7 is a schematic cross-sectional view showing another embodiment of a melt-blown filament die in the present invention.

FIG. 8 is a schematic cross-sectional view showing still another embodiment of a melt-blown filament die in the present invention.

Fig. 9 is a schematic cross-sectional view showing an embodiment of a melt-blown filament die not included in the present invention.

FIG. 10 is a schematic cross-sectional view showing another embodiment of a meltblown die head not encompassed by the present invention.

FIG. 11 is a schematic cross-sectional view showing still another embodiment of a melt-blown filament die in the present invention.

Detailed Description

The apparatus and method for producing a nonwoven fabric according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing one embodiment of a meltblown die head used in the present invention. FIG. 2 is a schematic cross-sectional view of a prior art melt-blown filament die without a widened wall surface on the lower surface of the die lip. Fig. 3 is a schematic side view showing an example of a device for producing nonwoven fabric. Fig. 4 is a view showing the direction of air flow immediately below the melt-blown filament die without providing a widened wall surface on the lower surface of the die lip in the conventional example. FIG. 5 shows the gas flow orientation directly below the meltblown die head in an embodiment of the invention. Fig. 6 is a view showing the direction of air flow immediately below the melt-blown filament die in other prior art examples not included in the present invention, although a widened wall surface is provided on the lower surface of the die lip. Fig. 7 and 8 are schematic cross-sectional views showing another embodiment of a melt-blown filament die of the present invention. In fig. 4 to 6, the direction of the arrow indicates the direction of the air flow. The term "immediately below the melt-blown filament die" as used herein means a region located below the discharge orifice of the spinneret of the melt-blown filament die with respect to the polymer discharge direction. These drawings are schematic diagrams for accurately conveying the gist of the present invention, and the drawings are simplified, and the melt-blown filament die of the present invention is not particularly limited, and the dimensional ratio and the like may be changed according to the embodiment.

As shown in fig. 3, the nonwoven fabric manufacturing apparatus used in the embodiment of the present invention is composed of a polymer introduction pipe 8, a melt-blown yarn die 9, a collecting wire conveyor 10, a roll 11, and the like. As shown in fig. 1, the melt-blown spinneret die 9 includes a spinneret plate 1 having a plurality of discharge holes 2 arranged in one direction (the depth direction of the paper in fig. 1) and a pair of die lips 3 arranged so as to face each other with the discharge hole group of the spinneret plate 1 interposed therebetween, and a slit-like gap 4 is formed between the spinneret plate 1 and each die lip 3.

In such a device configuration, the polymer is supplied from the polymer introduction pipe 8 to the melt-blown filament die 9, and a gas such as high-temperature air is also supplied to the melt-blown filament die 9, so that the molten polymer is discharged from the discharge holes 2 of the spinneret 1. In this case, the polymer may be supplied directly from the polymer introduction pipe 8 to the melt-blown yarn die 9, or may be introduced into the melt-blown yarn die 9 through a spinneret (not shown) including a hanger die. Then, a gas such as high-temperature air is blown from the gap 4 formed between the spinneret 1 and the die lip 3 to the polymer continuously discharged from the discharge holes 2, thereby drawing the polymer and reducing the diameter thereof, and simultaneously, the polymer is melt-bonded to form the web 12. The web 12 is collected by a collection-web conveyor 10 and wound around a roll 11 in the form of a nonwoven fabric. Instead of using the collecting wire conveyor 10, the polymer may be directly discharged onto a rotating roller and a gas such as high-temperature air may be blown to form the wire 12.

Here, since the polymer discharged from the discharge hole 2 is in a state of low viscosity and is drawn to a small diameter in a section (referred to as a stretch section) from the discharge hole 2 to several millimeters in the discharge direction of the polymer, it is important to efficiently express the drawing force in the stretch section. Here, when the traction force F is set to be CF and the constant is set to be the density ρ of the blown gas, the gas wind speed v in the stretching section, the circumferential length c of the linear polymer, and the length l of the stretching section, as shown in the formula (a), the traction force F is proportional to the square of the wind speed v of the gas flow and the length l of the stretching section.

F=cf×ρ×v ² Xc×l type (A)

Therefore, as a method for efficiently increasing the traction force F, it is conceivable to increase the gas wind speed v in the stretch zone and the length l of the stretch zone.

As means for this, for example, as shown in patent document 1, after the flow paths of the emitted gas flows are joined at the lower end portions of the slits, the flow path width is minimized and then enlarged, whereby the velocity v of the gas can be increased. However, according to this method, as shown in fig. 6, since a portion having a very narrow flow path width after the polymer is ejected extends in the polymer ejection direction, the jet flow easily flows along one side wall surface due to the coanda effect. As a result, the polymer discharged from the discharge hole 2 cannot flow straight in the discharge direction, and the length l of the stretching section becomes extremely short. Further, as described above, since the polymer is blown obliquely to the collecting wire conveyor 10, it may be difficult to stably produce a nonwoven fabric of ultrafine fibers.

In general, in a melt-blown spinneret, a jet is formed by blowing a gas at a higher velocity through a pair of gaps 4 and colliding the gas, and therefore, turbulence of the gas flow tends to be extremely large, and it is extremely difficult to stably form a jet portion immediately below the spinneret. The jet section is a high-speed region (generally, a region having a mach number of 0.3 or more) of the air stream blown out from the gap 4, and a region where the wind velocity v of the jet section is high becomes a stretching region. Therefore, in order to stably produce a nonwoven fabric of ultrafine fibers, it is necessary to stably and sufficiently secure the length l of the drawing section immediately below the melt-blown filament die and to increase the wind velocity v in this section.

Accordingly, the present inventors have conducted intensive studies on the above-mentioned problems which have not been considered in the prior art, and as a result, have found a novel technique of the present invention. That is, in the present invention, as shown in fig. 1 and 5, a pair of widened wall surfaces 6 extending in the polymer ejection direction are arranged starting from the lower surface of the die lip 3. Moreover, the angle alpha formed by the pair of widened wall surfaces 6 is in the range of 60 DEG≤alpha≤120 deg. When the intersection point between the lower surface of the die lip 3 and the wall surface forming the gap 4 is X and the intersection point between the lower surface of the die lip 3 and the widened wall surface 6 is Y, the interval P [ mm ] between the opposing intersection points X and the interval H [ mm ] between the opposing intersection points Y are in the range of 2≤H/P≤15.

Here, the difference between the form of the air flow immediately below the spinneret die in the embodiment of the present invention (fig. 5) having the widened wall surface with the above-described configuration and the embodiment of the present invention (fig. 4) will be described. In the embodiment of the conventional example shown in fig. 4, high-velocity gas blown out from the pair of gaps 4 collides with each other to form a jet portion, and the gas in the jet portion spreads downward from the gap at the opposing intersection point X. At this time, the companion flow flows into the jet part substantially vertically along the lower surface of the die lip 3, and the jet part gradually widens while being caught in the companion flow. With this jet section, the fibrous polymer is decelerated after being stretched, and landed on the mesh conveyor 10. On the other hand, in the embodiment of the present invention shown in fig. 5, the accompanying flow flows along the widening wall surface 6 and the lower surface of the die lip 3 with respect to the jet part blown out from the pair of gaps 4, and flows into the jet part from the direction opposite to the main flow direction (downward in the figure) of the jet part. As a result, in the jet section immediately below the spinneret die, 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 section is reduced, and the wind speed v of the drawing section is faster than in the conventional example. Further, the air flow flows along the widening wall surface 6 in a manner opposite to the main flow direction of the jet flow, thereby suppressing widening of the jet flow portion. As a result, the jet part becomes longer in the polymer ejection direction, and the stretch zone l increases. In this way, in the melt-blown yarn die according to the embodiment of the present invention, the length l of the drawing section and the wind speed v of the section are increased, and thus, a nonwoven fabric of ultrafine fibers can be stably produced.

In the present invention, as described above, the angle α between the pair of opposed widened wall surfaces 6 is set to be 60 ° or more and 120 ° or less, and the interval P [ mm ] between the intersection points X opposed to each other with the ejection hole 2 interposed therebetween and the interval H [ mm ] between the intersection points Y opposed to each other with the ejection hole 2 interposed therebetween are set to be 2 ° or less and H/P15 or less, but even if H/P satisfies 2 ° or less and H/P15 or less, when the angle α is α <60 ° as shown in patent document 1, the ejected polymer is biased to one widened wall surface 6 as shown in fig. 9, and it is difficult to obtain a nonwoven fabric of ultrafine fibers stably. On the other hand, when the angle α is α >120 °, the concomitant flow cannot narrow the jet portion, and the effect of reducing the diameter cannot be obtained.

In addition, even if the angle α satisfies the relationship of 60 ° +.alpha≤120°, in the case of H/P <2, the ejected polymer is biased to the widened wall surface 6 on one side as shown in fig. 10, and it is difficult to stably obtain a nonwoven fabric of ultrafine fibers. In addition, in the case of H/P >15, the flow cannot narrow the jet flow portion, and the effect of reducing the diameter cannot be obtained. In the present invention, by adjusting the conditions such that α is 60 ° or more and 120 ° or less and H/P is 2 ° or less and 15 ° or less, the jet flow directly below the spinneret plate 1 can be controlled, and a nonwoven fabric of ultrafine fibers can be stably produced.

The angle α is preferably in the range of 70 ° or more and 110 ° or less. Further, H/P is preferably in the range of 3≤H/P≤8. That is, the interval P [ mm ] determines the initial width of the jet section, and the interval H [ mm ] determines the widening of the jet on the downstream side of the jet, so that the ratio H/P becomes an important parameter for controlling the jet and further for reducing the diameter.

In the present invention, the interval P [ mm ] between the intersection points X facing each other across the ejection hole 2 is preferably in the range of 0.4≤P≤4.0. The air gap width needs to be set uniformly throughout the arrangement direction of the ejection holes (device width), and by setting 0.4P or less, it is easy to set the air gap width uniformly throughout the device width. On the other hand, when P is not more than 4.0, the jet velocity is increased, and the diameter is more easily reduced.

Preferably, the inclination of each of the pair of widened wall surfaces 6 can be arbitrarily changed. The member 5 constituting the widened wall surface 6 may be a block (japanese joint) or a plate, or may be integrally formed of the die lip 3 and the widened wall surface 6. The die lip is a portion that contributes to forming and restricting a flow path of the gas blown to the polymer together with the spinneret, and in the case of the integral structure, a lower surface of the portion including a tip (intersection point X) of the blown gas becomes a "lower surface of the die lip".

In the present invention, as shown in fig. 1, the tip of the spinneret 1 may be located at the same position as the lower surface of the die lip 3 with respect to the polymer discharge direction, and as shown in fig. 11, the tip of the spinneret 1 may be located further upstream than the lower surface of the die lip with respect to the polymer discharge direction, and may be located further downstream.

In the present invention, as shown in FIG. 7, the lower surface of the die lip 3 may not be perpendicular to the polymer ejection direction, and the angle β formed by the lower surface of the die lip and the polymer ejection direction is preferably 70≤β≤120 °. By setting β to 70 ° or more, the accompanying flow can be more reliably prevented from being deflected toward the widening wall surface 6 at the injection portion, and the collection by the conveyor belt can be more easily performed. However, if β is larger than 120 °, the lip tip becomes thinner, and thus not only is the processing difficult, but also the durability is liable to be lowered.

In the present invention, the length γ of the widened wall surface 6 in the polymer ejection direction is preferably 10mm or more. By setting γ to 10mm or more, the jet portion of the air flow emitted from the gap 4 can be reliably narrowed, and therefore the effect of reducing the diameter can be easily improved. In particular, the length γ is preferably in the range of 10mm to 50 mm. By setting the length γ to 50mm or less, the offset of the jet part to the widened wall surface 6 can be further prevented. In this case, the widening wall surface 6 is preferably configured by 2 or more widening members, and the widening member 6 is preferably detachable in the polymer ejection direction. The widened wall surface may be a stepped surface structure, not a straight line, on the connection surface of 2 or more widened members 6, but it is necessary to seal the member in a gas-tight manner. In this case, α and H are obtained based on the widening member 6 on the side contacting the lower surface of the die lip 3.

In the present invention, it is preferable that the widening member 5 constituting the widening wall surface 6 is movable in the horizontal direction along the lower surface of the die lip 3. This is because the polymer may adhere to the widened wall surface 6 in a state where the polymer discharge is unstable at the start of the operation of the apparatus, and the widened wall surface 6 is separated from the discharge hole 2 of the spinneret 1 at the start of the operation, and the widened member 5 is moved to a predetermined position at a stage where the discharge state is stable. The moving distance is preferably 10mm or more in the horizontal direction, and particularly preferably 50mm or more. The movement of the widening member 5 at this time is preferably performed using a push-pull of a bolt, a feed screw, or a rail mechanism.

In the present invention, it is preferable to provide a heating mechanism for widening the wall surface 6. Specifically, for example, the widening member 5 constituting the widening wall surface 6 is preferably heated by a heating means such as a heater. In the present invention, for example, the normal temperature accompanying flow flows along the widening wall surface 6 toward the spinneret 1, and the tip of the spinneret 1 is easily cooled by the widening section 5. As a result, the melt viscosity of the polymer increases during ejection, which hinders efficient stretching of the fiber, and there is a risk of reducing the effect of diameter reduction. Therefore, it is preferable to provide a heating means for widening the wall surface 6 to prevent the melt viscosity from rising at the time of polymer ejection. The type of heater may be a rod or a plate, but is more preferably a plate from the viewpoint of uniformity. The heat quantity of the heater is preferably 1.2KW/m or more. Further, instead of the heating means, the surface of the widening member may be covered with an insulating plate having low heat conductivity, and the heat conductivity is preferably 1.0W/m/K or less.

Further, in the present invention, as shown in fig. 8, the widened wall surface 6 may have an R portion which is gradually close to the lower surface of the die lip 3, in addition to the planar portion, in the vicinity of the lower surface of the die lip 3. In the present invention, as described above, since the widening of the jet part of the air immediately below the spinneret is suppressed by the inflow of the accompanying flow along the widening wall surface 6, the effect of reducing the diameter is also exhibited by forming the R part in a range where the main flow of the accompanying flow is not affected.

In the present invention, the arithmetic average roughness Ra of the widened wall surface is preferably 100 μm or less. When Ra >100 μm, the arithmetic average roughness Ra of the widened wall surface tends to generate a vortex due to the irregularities of the widened wall surface 6, and the effect of reducing the diameter may be reduced as the turbulence of the flow increases. In addition, the direction of the node generated by the processing of the widened wall surface 6 is preferably parallel to the direction of the air flow in the vicinity of the widened wall surface 6 shown in fig. 5, because it is possible to suppress the generation of the vortex.

As a material of the widening member used in the present invention, a metal material such as stainless steel or aluminum, or a plastic material such as glass fiber can be preferably used.

The present invention is extremely versatile and can be applied to the production of known melt-blown nonwoven fabrics. Therefore, the polymer constituting the nonwoven fabric is not particularly limited. Examples of the polymer constituting the nonwoven fabric include polyester, polyamide, polyphenylene sulfide, polyethylene, polypropylene, and the like. The MFR (melt flow rate) of the polymer is preferably 300 to 1500g/10 min, particularly preferably 900 to 1300g/10 min. The polymer may contain various functional particles such as a matting agent such as titanium dioxide, silicon oxide, potassium ions, a coloring inhibitor, a stabilizer, an antioxidant, a deodorant, a flame retardant, a silk friction reducing agent, a coloring pigment, and a surface modifier, or an additive such as an organic compound, or may contain copolymerization, within a range not impairing the stability of the silk production. In addition, a polymer solution may be used in which a polymer such as cellulose, polysulfone, polyetherimide, or polyacrylonitrile is dissolved in a solvent. The spinning temperature of the polymer is preferably set to a melting point of +60 ℃ or less based on the melting point of the polymer used.

In the present invention, the gas blown from the gap 4 is preferably the most economical air, but may be a mixed gas, vapor, saturated vapor, or superheated vapor. In order to improve the traction force, as shown in the above formula (a), since the density ρ of the gas is also related, it is preferable to select a gas having a high density. The temperature of the gas may be set in a range from the ejected polymer temperature to +50℃.

In the present invention, the flow rate of the gas supplied from the left-right gap 4 may be different.

Examples

The effects of the manufacturing apparatus and the manufacturing method of the present invention will be specifically described below by way of examples. The measurement method of the characteristic value in the examples and the like are as follows.

< Deflection of airflow >

For the deflection of the air flow, an anemometer (MODEL 6501 series, japan Kanomax corporation) was used for the spinning, and the evaluation was performed at the center of the device width. Specifically, for the left and right widened wall surfaces, a probe of an anemometer was provided at a position 10mm downstream in the polymer discharge direction from the spinneret discharge surface and at a position 2mm inside from the widened wall surface, and the wind speed was measured every 1 second, and an average value of 10 seconds was used. When the obtained wind speed value is 5 times or more different from the left and right wall surfaces, it is determined that there is a deviation of the airflow.

< Average fiber diameter >

After removing the non-woven fabric collected on the collecting mesh conveyor except 50mm in the center in the width direction, small pieces of samples were collected at random. Photographs of each of the small pieces of samples were taken with an electron microscope, 100 of them were randomly extracted to determine fiber diameters, and arithmetic average values were obtained.

Comparative example 1

The nonwoven fabric was produced using the melt-blown filament die shown in fig. 2 (i.e., the widened wall surface on the lower surface side of the die lip). As a raw material resin, a polypropylene resin having a weight of 2.16Kg and a melt flow rate of 1100g/10 min at a temperature of 230℃was used in accordance with ASTM-D1238, and the melt resin temperature was 280℃and the number of spinneret holes was 150, the pitch of the spinneret discharge holes was 1mm, the spinneret aperture was 0.4mm, the single hole discharge amount was 0.1g/min, the gap width of the hot air supply on the lower surface of the die lip was 1.5mm, the hot air flow rate was 560Nm ³/(hr.m), and the angle between the lower surface of the die lip and the polymer discharge direction was 90 ° (β=90°), and 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 was collected on a conveyor belt, and the average fiber diameter was 1.1. Mu.m.

(Example 1 to 10, comparative example 2 to 6)

The nonwoven fabric was produced using the melt-blown filament die shown in fig. 1 (i.e., the widened wall surface on the lower surface side with the die lip). As a raw material resin, a polypropylene resin having a weight of 2.16Kg and a melt flow rate of 1100g/10 min at a temperature of 230℃was used in accordance with ASTM-D1238, and the melt resin temperature was 280℃and the number of spinneret holes was 150, the pitch of the spinneret holes was 1mm, the spinneret hole diameter was 0.4mm, the single hole discharge amount was 0.1g/min, the gap width of the hot air supply on the lower surface of the die lip was 1.5mm, the hot air flow rate was 560Nm ³/(hr.m), and the widening member was heated without using a heater, and nonwoven fabrics were produced under the conditions shown in tables 2 to 4. The test results are shown in tables 2 to 4.

In examples 1 to 10 in which the angle α formed by the opposing widened wall surfaces was in the range of 60 ° to 120 ° and the ratio H/P of the interval P between the intersections X to the interval H between the intersections Y was in the range of 2 to 15, the jet flow immediately below the spinneret die was controlled, and the nonwoven fabric of ultrafine fibers was stably produced. In examples 6 and 8, the resin was occasionally deposited on the widened wall surface, and therefore, it was necessary to remove the attached polymer periodically, but the continuous production of the stable nonwoven fabric was not hindered.

On the other hand, in comparative example 2, the production of nonwoven fabric was attempted in the same manner as in example 2 except that the angle α formed by the opposing widened wall surfaces was changed to 50 °, and the ratio H/P of the interval P between the intersections X and the interval H between the intersections Y was changed to 1, and as a result, the air flow flowed along one wall surface, and the nonwoven fabric could not be trapped on the conveyor belt.

In comparative example 3, the production of nonwoven fabric was attempted in the same manner as in example 2 except that the angle α formed by the opposing widened wall surfaces was changed to 50 °, but the air flow was caused to flow along one wall surface, and the nonwoven fabric could not be trapped on the conveyor belt.

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 intersections X and the interval H between the intersections Y was changed to 1, but the air flow was caused to flow along one side wall surface, and the nonwoven fabric could not be collected on the conveyor belt.

In comparative example 5, 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 intersections X and the interval H between the intersections Y was changed to 21, and as a result, although nonwoven fabric could be obtained, the incident flow could not be narrowed, and the effect of reducing the diameter could not be obtained.

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 opposed widened wall surfaces was changed to 150 °, and as a result, although nonwoven fabric could be obtained, the incident flow could not narrow the emitted air flow, and the effect of reducing the diameter could not be obtained.

Comparative example 7

The nonwoven fabric was produced using the melt-blown die shown in FIG. 2 (i.e., the widened wall surface on the lower surface side of the die lip) under the same conditions as in comparative example 1 except that the gap width was 0.5mm, the hot air flow rate was 450Nm ³/(hr.m), and the conditions were the same. The test results are shown in Table 5. In comparative example 7, the nonwoven fabric was trapped on a conveyor belt, and the average fiber diameter was 1.1. Mu.m.

(Examples 11 to 13, comparative examples 8 and 9)

The melt-blown yarn die shown in FIG. 1 (i.e., the widened wall surface on the lower surface side of the die lip) was used, the gap width was set to 0.5mm, the hot air flow rate was set to 450Nm ³/(hr. M), the angle α formed by the opposing wall surfaces was set to 90 °, the length γ of the widened wall surface in the polymer ejection direction was set to 30mm, the arithmetic average roughness Ra of the widened wall surface was set to 12.5 μm, and the widening member was heated without using a heater, and nonwoven fabrics were produced under the conditions shown in Table 5.

In examples 11 to 13 in which the ratio H/P of the interval P between the intersections X and the interval H between the intersections Y is in the range of 2 to 15, the jet flow immediately below the spinneret die can be controlled, and the nonwoven fabric of ultrafine fibers can be stably produced.

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 intersections X and the interval H between the intersections Y was changed to 1, but the air flow was caused to flow along one side wall surface, and the nonwoven fabric could not be collected on the conveyor belt.

In comparative example 9, 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 intersections X and the interval H between the intersections Y was changed to 25, and as a result, although nonwoven fabric could be obtained, the incident flow could not be narrowed, and the effect of reducing the diameter could not be obtained.

Example 14

The melt-blown filament die shown in FIG. 1 (i.e., the widened wall surface on the lower surface side of the die lip) was used, the gap width was set to 0.5mm, the hot air flow rate was set to 450Nm ³/(hr. M), the angle α formed by the opposing wall surfaces was 90%, the length γ of the widened wall surface in the polymer ejection direction was 30mm, the arithmetic average roughness Ra of the widened wall surface was 12.5 μm, and the widened member was heated (heating surface: the opposite side of the widened wall surface) at 2.0KW/m by using a plate heater, and nonwoven fabric was produced under the conditions shown in Table 5.

A nonwoven fabric containing finer ultrafine fibers can be stably produced as compared with example 12 without the heating widening section.

TABLE 1

Watch (watch)

		Comparative example 1
			Angle alpha formed by the opposite widened wall surfaces	Degree (°)	-
H/P	-	-
			Angle beta between the lower surface of the die lip and the polymer ejection direction	Degree (°)	90
Length gamma of widened wall surface in polymer ejection direction	mm	-
			Arithmetic average roughness Ra of widened wall surface	μm	-
Heating widening member with heater	-	Without any means for
			Deviation of air flow	-	Without any means for
Average fiber diameter	μm	1.1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Industrial applicability

The nonwoven fabric produced by the production apparatus and the production method of the present invention can be used as industrial filters, diapers, physiological products, medical masks, gowns for medical use, pollen protection masks, sanitary materials such as curtains, automotive materials, filters for liquid filtration, interleaving papers, industrial materials such as automotive brushes, food packaging materials, cloth, band yarns, shoe materials, heating patches, living materials such as tea bags, cleaning masks, agricultural materials such as agricultural basins, roofing materials, civil engineering stabilization sheets, heat insulating materials, flooring materials, building materials such as house wrap, civil engineering materials, etc., but the scope of application is not limited thereto.

Description of the reference numerals

1. Spinneret plate

2. Jet hole

3. Die lip

4. Gap of

5. Widening component

6. Widening the wall surface

7. The main polymer track after ejection

8. Polymer ingress pipe

9. Melt-blown filament die head

10. Trapping net type conveyor

11. Roller

12. Net

13. Boundary of the areas of the jet and non-jet portions

Intersection point of lower surface of X-die lip and wall surface forming gap

Intersection point of lower surface of Y-die lip and widened wall surface

Angle of alpha-opposite widened wall surfaces

Angle formed by lower surface of beta die lip and polymer spraying direction

Length of gamma-widening wall in polymer ejection direction

Length of stretch zone

W jet width

H is arranged at intervals between intersection points Y opposed to each other with the ejection hole interposed therebetween

P is arranged at an interval between intersection points X opposed to each other with the ejection hole interposed therebetween

Claims (7)

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 an 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 , wherein a 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 , wherein the widening wall surface is movable in a direction intersecting with a polymer ejection direction. 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, comprising using the apparatus according to any one of claims 1 to 6.