Meltblown device

Abstract

The present invention provides a meltblowing device capable of appropriately changing the fiber density of the obtained ultrafine fiber nonwoven fabric and the fiber diameter of the ultrafine fibers. The meltblowing device is composed of a meltblowing die (10), a hot air ejection hole forming die (7), and a nozzle hole forming die (8). The lower surface of the hot air ejection hole forming die (7) has a first flat surface (72) and a first inclined surface (73). The first inclined surface is a smooth surface as a whole. The upper surface of the nozzle hole forming die has a second flat surface (82) and a second inclined surface (83). A polymer storage recess (85) to which a polymer is supplied from a second polymer flow path (32) is provided on the second inclined surface. In addition, a second groove (84) is formed near the front end of the second inclined surface. The polymer flows from the polymer storage recess (85) into the second groove through the first polymer flow path (31) and the second polymer flow path, becomes ultrafine fibers from the front end of the second groove (84) which becomes the nozzle hole (2), and is discharged.

Description

Technical Field

[0001] The present invention relates to a melt-blowing device for producing ultrafine fiber nonwoven fabrics, and in particular to a melt-blowing device that can easily and appropriately change the diameter of ultrafine fibers and the fiber density of the ultrafine fiber nonwoven fabrics. Background Art

[0002] Traditionally, ultrafine fiber nonwoven fabrics have been produced using a roughly rectangular meltblowing device equipped with a nozzle hole for discharging a molten thermoplastic polymer and slits (hot air ejection holes) for ejecting hot air from both sides of the nozzle hole. Multiple nozzle holes are arranged in rows parallel to the length of the roughly rectangular meltblowing device. The meltblowing device is configured so that the length direction corresponds to the width direction of the ultrafine fiber nonwoven fabric. Multiple ultrafine fibers are ejected from the nozzle holes and stacked to produce the ultrafine fiber nonwoven fabric.

[0003] The cross-sectional diagram of such a meltblowing device is as follows Figure 1 As shown. That is, the front and back directions of the paper become the longitudinal direction of the meltblowing device 1, and a plurality of nozzle holes 2 are arranged in a row at predetermined intervals in the longitudinal direction of the meltblowing device 1 (the front and back directions of the paper). The melted thermoplastic polymer flows downward from the polymer flow path 3 and reaches the nozzle hole 2 from the upper end of the nozzle. On the other hand, hot air is ejected from the pipes 6, 6 for circulating pressurized hot air through the hot air flow paths 5, 5 from the slits 4, 4 provided on both sides of the nozzle hole 2. Therefore, the thermoplastic polymer reaching the nozzle hole 2 is blown in the axial direction of the nozzle by the hot air ejected from the slits 4, 4, thereby obtaining ultrafine fibers. In addition, when observing the positional relationship between the nozzle hole 2 and the slit 4 from above, if a part of it is shown schematically, it becomes Figure 2 That kind of positional relationship.

[0004] On the other hand, Patent Document 1 describes a method for Figure 1 The invention is a device in which the positional relationship between the rows of nozzle holes 2 and the slits 4 in the meltblowing device 1 is reversed (Patent Document 1, Figure 3a). If Figure 3a of Patent Document 1 is reproduced, it will be as follows Figure 3 As shown. Figure 3 Reference numeral 18 corresponds to the nozzle hole 2, and reference numeral 22 corresponds to the slit 4. This invention has the advantage of doubling the basis weight of the resulting ultrafine fiber nonwoven fabric by discharging molten thermoplastic polymer from two rows of nozzle holes relative to one slit 4. Furthermore, supplying different types of thermoplastic polymers to one row of nozzle holes 2 and another row of nozzle holes 2 allows for a mixed-weave ultrafine fiber nonwoven fabric to be obtained.

[0005] Patent Document 1: Japanese Patent Publication No. 6-60448 Summary of the Invention

[0006] An object of the present invention is to provide a melt-blowing device that improves the invention described in Patent Document 1 and can appropriately change the fiber density of the obtained ultrafine fiber nonwoven fabric and the fiber diameter of the ultrafine fibers.

[0007] The present invention solves the above-mentioned problems by designing a nozzle hole forming unit. Specifically, the present invention relates to a meltblowing device comprising a meltblowing die, a hot air ejection hole forming die disposed below the meltblowing die, and a nozzle hole forming die disposed below the hot air ejection hole forming die. The meltblowing device is characterized in that a first polymer flow path extending in a vertical direction is provided in the hot air ejection hole forming die, the hot air ejection hole forming die has a lower surface including a first flat surface and a first inclined surface inclined downwardly relative to the first flat surface, a first groove is formed near the front end of the first inclined surface, a second polymer flow path communicating with the first polymer flow path is provided in the nozzle hole forming die, and the upper surface of the nozzle hole forming die has a second flat surface and a second inclined surface inclined downwardly relative to the second flat surface, a smooth surface and a polymer storage recess are provided on the second inclined surface for supplying polymer from the second polymer flow path, and the first flat surface is brought into contact with the second flat surface, and the first inclined surface is brought into contact with the smooth surface of the second inclined surface, so that the front end of the first groove becomes a nozzle hole.

[0008] In addition, it is also possible to form a first groove near the front end of the first inclined surface of the hot air ejection hole forming mold without forming the first groove and make the first inclined surface a smooth surface, and form a second groove near the front end of the second inclined surface of the nozzle hole forming mold, and make the front end of the second groove become the nozzle hole.

[0009] In addition, the first groove and the second groove can be made consistent, and the hole formed by the front ends of the first groove and the second groove can become the nozzle hole. The first groove and the second groove can also be staggered, and the front ends of the first groove and the second groove can respectively become nozzle holes.

[0010] The nozzle holes of the meltblowing device according to the present invention are formed by a first groove on a first inclined surface of the lower surface of the hot air ejection hole forming die and / or a second groove on a second inclined surface of the upper surface of the nozzle hole forming die. Therefore, the size or number of the nozzle holes can be appropriately changed by combining the hot air ejection hole forming die and / or the nozzle hole forming die. This provides the following advantages: ultrafine fibers having a desired fiber diameter and a desired fiber density can be easily obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a cross-sectional schematic diagram of an existing meltblowing device.

[0012] Figure 2 yes Figure 1 Schematic bottom view of the meltblowing device, showing the positional relationship between the nozzle hole 2 and the slit 4.

[0013] Figure 3 This figure is a reproduction of FIG. 3a of Patent Document 1, and shows the positional relationship between the nozzle hole 2 (18) and the slit 4 (22).

[0014] Figure 4 1 is a schematic cross-sectional view of a meltblowing device according to an example of the present invention.

[0015] Figure 5 This is a schematic side view of an example of a hot air ejection hole forming die used in the present invention.

[0016] Figure 6 yes Figure 5 An example of a schematic left side view of a hot air ejection hole forming mold is shown.

[0017] Figure 7 This is a schematic side view of an example of a nozzle hole forming die used in the present invention.

[0018] Figure 8 yes Figure 7 An example of a schematic right side view of a nozzle hole forming mold is shown.

[0019] Figure 9 yes Figure 7 Another example of a schematic right side view of a nozzle hole forming mold is shown.

[0020] Figure 10 It is a schematic bottom view of a meltblowing device according to an example of the present invention, showing the configuration of the nozzle hole 2 and the slit 4 .

[0021] Figure 11 It is a schematic bottom view of a meltblowing device according to another example of the present invention, showing the configuration of the nozzle hole 2 and the slit 4 .

[0022] Figure 12 It is a schematic bottom view of a meltblowing device according to another example of the present invention, showing the configuration of the nozzle hole 2 and the slit 4 .

[0023] Figure 13 It is a schematic bottom view of a meltblowing device according to another example of the present invention, showing the configuration of the nozzle hole 2 and the slit 4 .

[0024] Description of Reference Numerals

[0025] 1...meltblowing device; 2...nozzle hole; 3...polymer flow path; 4...slit; 5...hot air flow path; 6...pipe; 7...hot air ejection hole forming mold; 8...nozzle hole forming mold; 10...meltblowing mold; 12...bolt; 13...bolt; 14...pin; 31...first polymer flow path; 32...second polymer flow path; 70...side surface of the hot air ejection hole forming mold; 71...top surface of the hot air ejection hole forming mold; 72...first flat surface of the bottom surface of the hot air ejection hole forming mold; 73...first inclined surface of the bottom surface of the hot air ejection hole forming mold; 74...first groove provided near the front end of the first inclined surface 73; 82...second flat surface of the top surface of the nozzle hole forming mold; 83...second inclined surface of the top surface of the nozzle hole forming mold; 84...second groove provided near the front end of the second inclined surface 83; 85...polymer storage recess provided on the second inclined surface 83. DETAILED DESCRIPTION

[0026] like Figure 4 As shown, a meltblowing apparatus 1 according to an example of the present invention is composed of a meltblowing die 10, a hot air ejection hole forming die 7 provided below the meltblowing die 10, and a nozzle hole forming die 8 provided below the hot air ejection hole forming die 7. The meltblowing die 10 is provided with a polymer flow path 3 through which a molten thermoplastic polymer flows downward, and a pipe 6 through which pressurized hot air flows.

[0027] A first polymer flow path 31 is provided in the upper and lower directions on the hot air ejection hole forming mold 7 provided at the lower level of the meltblowing mold 10. The first polymer flow path 31 is connected to the polymer flow path 3 and the second polymer flow path 32. The upper surface 71 of the hot air ejection hole forming mold 7 is a smooth surface, which abuts against the lower surface of the meltblowing mold 10 and is screwed to the lower surface of the meltblowing mold 10 by bolts 13, thereby fixing the two. In the case where the hot air ejection hole is a slit 4, before the fixation, the left and right directions are positioned by the first positioning pin 11, so that the width of the slit 4 can be determined. The width of the slit 4 is usually determined to be within the range of 0.3 to 5 mm. The lower surface of the hot air ejection hole forming mold 7 has a first flat surface 72 and a first inclined surface 73 ( Figure 5 The first flat surface 72 is parallel to the upper surface 71. The first inclined surface 73 is inclined downward at an angle of 110 to 160 degrees relative to the first flat surface 72. Figure 6As shown, a first groove 74 is formed near the front end of the first inclined surface 73. This first groove 74, alone or in conjunction with the second groove 84, forms the nozzle hole 2. If the second groove 84 alone forms the nozzle hole 2, the first groove 74 is unnecessary, and the entire first inclined surface 73 is a smooth surface. In the figure, the portion coated with thick ink is a smooth surface.

[0028] The nozzle hole forming mold 8 provided at the lower stage of the hot air ejection hole forming mold 7 is provided with a second polymer flow path 32 communicating with the first polymer flow path 31. The upper surface of the nozzle hole forming mold 8 includes a second flat surface 82 and a second inclined surface 83 ( Figure 7 The second flat surface 82 is parallel to the first flat surface 72, and the second inclined surface 83 is parallel to the first inclined surface 73. Figure 8 As shown, a polymer reservoir recess 85 communicating with the second polymer flow path 32 is provided on the second inclined surface 83. The polymer flowing into the polymer reservoir recess 85 is discharged from the nozzle hole 2 formed solely by the first groove 74. A second groove 84 communicating with the polymer reservoir recess 85 may also be provided on the second inclined surface 83.

[0029] Hereinafter, a case where various nozzle holes 2 are formed by combining the hot air ejection hole forming die 7 and the nozzle hole forming die 8 will be described.

[0030] (1) When the first groove 74 is formed on the first inclined surface 73 of the hot air ejection hole forming mold 7, and the second groove 84 is not formed on the second inclined surface 83 of the nozzle hole forming mold 8 but is a smooth surface

[0031] When the meltblowing device is assembled by bringing the first flat surface 72 of the hot air ejection hole forming die 7 into contact with the second flat surface 82 of the nozzle hole forming die 8, and bringing the first inclined surface 73 into contact with the second inclined surface 83, the configuration of the nozzle hole 2 and the slit 4 is represented by a schematic bottom view of the meltblowing device. Figure 10 That is, on both sides of the slit 4 formed by the side surface 70 of the hot air ejection hole forming die 7, there are formed nozzle holes 2, which are formed by first grooves 74 provided near the front end of the first inclined surface 73 of the hot air ejection hole forming die 7. The polymer flows from the polymer storage recess 85 of the nozzle hole forming die 8 into the first grooves 74 and, along with the hot air ejected from the slit 4, is discharged from the nozzle hole 2 as ultrafine fibers.

[0032] (2) When the first inclined surface 73 of the hot air ejection hole forming mold 7 is not formed with the first groove 74 and is entirely smooth, and the second inclined surface 83 of the nozzle hole forming mold 8 is formed with the second groove 84

[0033] When the hot air ejection hole forming die 7 and the nozzle hole forming die 8 are arranged in the same manner as above and a melt-blowing device is assembled, if the shape of the nozzle hole 2 and the slit 4 is represented by a schematic bottom view of the melt-blowing device, as shown in FIG. Figure 11 That is, on both sides of the slit 4 formed by the side surface 70 of the hot air ejection hole forming die 7, there are formed nozzle holes 2 consisting of second grooves 84 provided near the front end of the second inclined surface 83 of the nozzle hole forming die 8. The polymer flows from the polymer storage recess 85 of the nozzle hole forming die 8 into the second grooves 84 and is discharged from the nozzle hole 2 together with the hot air ejected from the slit 4 as ultrafine fibers. In addition, Figure 4 The schematic cross-sectional view of a meltblowing device according to an example of the present invention shown is a case of this embodiment.

[0034] (3) A case where the first groove 74 is formed on the first inclined surface 73 of the hot air ejection hole forming mold 7 and the second groove 84 is formed on the second inclined surface 83 of the nozzle hole forming mold 8

[0035] When the hot air ejection hole forming mold 7 and the nozzle hole forming mold 8 are arranged in the same manner as above, and the melt-blowing device is assembled in such a manner that the first groove 74 and the second groove 84 are aligned, if the shape of the nozzle hole 2 and the slit 4 is represented by a schematic bottom view of the melt-blowing device, as shown in FIG. Figure 12 That is, on both sides of the slit 4 formed by the side surface 70 of the hot air ejection hole forming die 7, the nozzle hole 2 is formed by a first groove 74 provided near the front end of the first inclined surface 73 of the hot air ejection hole forming die 7 and a second groove 84 provided near the front end of the second inclined surface 83 of the nozzle hole forming die 8. The polymer flows from the polymer storage recess 85 of the nozzle hole forming die 8 into the first groove 74 and the second groove 84, and together with the hot air ejected from the slit 4, is discharged from the nozzle hole 2 as ultrafine fibers.

[0036] (4) When the first groove 74 is formed on the first inclined surface 73 of the hot air ejection hole forming mold 7 and the second groove 84 is formed on the second inclined surface 83 of the nozzle hole forming mold 8

[0037] When the hot air ejection hole forming mold 7 and the nozzle hole forming mold 8 are arranged in the same manner as above, and the melt-blowing device is assembled in a manner such that the first groove 74 and the second groove 84 are staggered so as not to be aligned, if the configuration of the nozzle hole 2 and the slit 4 is represented by a schematic bottom view of the melt-blowing device, as shown in FIG. Figure 13That is, on both sides of the slit 4 formed by the side surface 70 of the hot air ejection hole forming die 7, the nozzle holes 2 are formed separately. These are formed by a first groove 74 provided near the front end of the first inclined surface 73 of the hot air ejection hole forming die 7, and a second groove 84 provided near the front end of the second inclined surface 83 of the nozzle hole forming die 8. The polymer flows from the polymer reservoir 85 of the nozzle hole forming die 8 into the first groove 74 and the second groove 84, and is then discharged from the nozzle hole 2 as ultrafine fibers along with the hot air ejected from the slit 4.

[0038] As described above, after the nozzle holes 2 are formed by assembling the nozzle hole forming die 8 and the hot air ejection hole forming die 7, removing the nozzle hole forming die 8 facilitates the removal of contaminants from the first and second grooves 74, 84, which may have occurred during the production of the ultrafine fiber nonwoven fabric. Furthermore, when assembling the meltblowing apparatus by abutting the first flat surface 72 of the hot air ejection hole forming die 7 against the second flat surface 82 of the nozzle hole forming die 8 and abutting the first inclined surface 73 against the second inclined surface 83, it is preferable to secure the hot air ejection hole forming die 7 and the nozzle hole forming die 8 together using bolts 12 that penetrate through the first and second flat surfaces 72, 82. In particular, it is preferable to screw the bolts 12 outside the first and second polymer flow paths 31, 32, i.e., so that they do not contact the first and second polymer flow paths 31, 32. This prevents the bolts 12 from being located within the first and second polymer flow paths 31, 32, thereby preventing the flow of the polymer from being obstructed. In addition, if the position of the nozzle hole forming die 8 is determined by the second positioning pin 14 before the screw 12 is screwed, the position of the second groove 84 can be arbitrarily deviated in the longitudinal direction of the meltblowing device.

[0039] In the above example, the case where the nozzle holes 2 are provided on both sides of the slit 4 is described, but the nozzle hole 2 may be formed only on one side of the slit 4. In addition, the first groove 74 and the second groove 84 are grooves with a semicircular cross section, but they may be grooves of other shapes. For example, they may be quadrilateral, triangular, or U-shaped in cross section. The number of the first groove 74 and the second groove 84 may be arbitrary, and may usually be 10 to 100 per inch. In addition, the hot air ejection hole is made into the slit 4 that is the entire column of the nozzle holes 2, but it can be changed appropriately. For example, a column of holes with a circular cross section or a quadrilateral cross section may be made as the hot air ejection hole in synchronization with the column of the nozzle holes 2. In addition, bolts 12 and 13 are used to fix the hot air ejection hole forming mold 7 and the nozzle hole forming mold 8, but other fixing means may also be used.

Claims

1. A meltblowing device, comprising a meltblowing die, a hot air ejection hole forming die arranged below the meltblowing die, and a nozzle hole forming die arranged below the hot air ejection hole forming die. The melt-blowing device is characterized in that The hot air ejection hole forming die is provided with a first polymer flow path running in the vertical direction. The lower surface of the hot air ejection hole forming mold comprises a first flat surface and a first inclined surface inclined downward relative to the first flat surface, and a first groove is formed near the front end of the first inclined surface. The nozzle hole forming die is provided with a second polymer flow path communicating with the first polymer flow path. The upper surface of the nozzle hole forming mold includes a second flat surface and a second inclined surface inclined downward relative to the second flat surface, and the second inclined surface is provided with a smooth surface and a polymer storage recess to which the polymer is supplied from the second polymer flow path. The first flat surface is brought into contact with the second flat surface, and the first inclined surface is brought into contact with the smooth surface portion of the second inclined surface, so that the front end of the first groove becomes the nozzle hole.

2. The meltblowing device according to claim 1, characterized in that The first groove is not formed near the front end of the first inclined surface, making the entire surface smooth, and the second groove is formed near the front end of the second inclined surface, so that the front end of the second groove serves as the nozzle hole.

3. The meltblowing device according to claim 1, characterized in that By forming a second groove near the front end of the second inclined surface and aligning the first groove with the second groove, a hole formed by the front ends of the first groove and the second groove becomes the nozzle hole.

4. The meltblowing device according to claim 1, characterized in that By forming the second groove near the front end of the second inclined surface, the first groove and the second groove are offset so as not to coincide with each other, so that the front ends of the first groove and the second groove respectively serve as nozzle holes.

5. The meltblowing device according to claim 1, characterized in that The hot air ejection hole forming die and the nozzle hole forming die are fixed by screwing bolts penetrating the first flat surface and the second flat surface outside the first polymer flow path and the second polymer flow path.

6. The meltblowing device according to claim 1, characterized in that The hot air ejection holes formed by the hot air ejection hole forming die are in the form of slits, and the width thereof is 0.3 to 5 mm.

7. The meltblowing device according to claim 1, characterized in that The angle formed by the first flat surface and the first inclined surface is 110 to 160 degrees.

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