Method for producing electret fiber sheet

Abstract

To provide a device for producing an electret fiber sheet capable of sufficient electretization without causing large damage to a fiber.SOLUTION: A method for producing an electret fiber sheet comprising: conveying means 2 for transporting the fiber sheet 9; water droplet generating means 3 consisting of a spray nozzle 31 that generates water droplets; adhering means 4 for approximately uniformly dispersing and attaching water consisting of the water droplets generated by the water droplet generating means 3 to one surface 9a of the fiber sheet 9 during transportation by the conveying means 2, and suction means 5 provided at a position corresponding to the adhering means 4 on the other side of the fiber sheet 9, which suctions the water that is approximately uniformly dispersed and attached to one surface 9a of the fiber sheet 9 by means of the adhering means 4, allowing the water to permeate and pass through the fiber sheet 9.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus for manufacturing an electret fiber sheet.

Background Art

[0002] Conventionally, electrified fibers have been used for high-performance filter media. As a method for producing an electret fiber sheet, there is a method of making the fiber sheet come into contact with water to electrify it (hereinafter referred to as the "hydrocharge method"). Specifically, for example, a method of spraying a water jet with sufficient pressure to electrify it, a method of sucking water with a nozzle to penetrate the fiber sheet with water to electrify it, a method of spraying and sucking fine water droplets, etc. have been proposed (see Patent Documents 1 to 3).

[0003] However, when water is made to penetrate the fiber sheet with strong pressure or suction force, there is a problem that the fibers are greatly damaged and fuzzing or the like occurs. In addition, those that spray and suck fine water droplets have a problem that even if the spray amount is increased, water cannot sufficiently penetrate and pass through the inside of the fibers, and it is difficult to achieve sufficient electrification.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, in view of the above situation, the problem to be solved by the present invention is to provide a manufacturing apparatus for an electret fiber sheet capable of sufficient electretization even using minute water droplets without causing significant damage to the fibers of the fiber sheet.

Means for Solving the Problems

[0006] In view of such a situation, the present inventor earnestly studied, and as a result, as shown in FIG. 8, the sprayed water droplets aggregate on the surface of the fiber sheet 9 (aggregated water droplets 8), and even when sucked, only the surrounding air is sucked and they do not enter the inside of the fibers. Also, due to such aggregation, the portion on which the aggregated water droplets 8 are located has a larger suction pressure loss compared to other portions, and only the portion where the aggregated water droplets 8 do not exist is sucked, and water droplets do not pass through the portion below the aggregated water droplets 8, resulting in a non-uniform distribution of water droplets over the entire fiber sheet 9 and insufficient electretization (the dust collection effect does not improve). Having found this, the present invention has been completed.

[0007] That is, the present invention includes the following inventions.

[0008] (1) A manufacturing apparatus for an electret fiber sheet, comprising: a conveying means for conveying a fiber sheet; a water droplet generating means comprising a spray nozzle for generating water droplets; an adhering means for dispersing and adhering water composed of the water droplets generated by the water droplet generating means substantially uniformly on one surface of the fiber sheet being conveyed by the conveying means; and a suction means provided at a position corresponding to the adhering means on the other side of the fiber sheet, for sucking the water substantially uniformly dispersed and adhered on one surface of the fiber sheet by the adhering means and causing the water to penetrate and pass through the fiber sheet.

[0009] (2) The manufacturing apparatus for an electret fiber sheet according to (1), wherein the spray nozzle is provided at a position for directly adhering the generated water droplets to the one surface of the fiber sheet, the adhering means is provided on the conveyance downstream side of the fiber sheet with respect to the spray nozzle, and comprises a contact body that contacts the one surface of the fiber sheet, and the contact body spreads the water droplets directly adhered to the one surface on the surface and disperses and adheres them substantially uniformly.

[0010] (3) The contact body is a rotating roller that rotates in synchronization with the fiber sheet, an endless belt that moves in synchronization with the fiber sheet, or a cantilever flexible sheet that is supported at one end on the upstream side in the conveying direction and whose downstream side is in frictional contact with the fiber sheet, and is the manufacturing apparatus for an electret fiber sheet according to (2).

[0011] (4) The adhering means is a rotating roller that contacts one surface of the fiber sheet and rotates in synchronization with the fiber sheet, and the spray nozzle is provided at a position where the generated water droplets are adhered to the outer peripheral surface of the rotating roller. The rotating roller simultaneously transfers the water droplets adhered to the outer peripheral surface onto one surface of the fiber sheet by contact and spreads them on the surface, dispersing and adhering them substantially uniformly, and is the manufacturing apparatus for an electret fiber sheet according to (1).

[0012] (5) The adhering means is an endless belt that contacts one surface of the fiber sheet and moves in synchronization with the fiber sheet, and the spray nozzle is provided at a position where the generated water droplets are adhered to the outer peripheral surface of the endless belt. The endless belt simultaneously transfers the water droplets adhered to the outer peripheral surface onto one surface of the fiber sheet by contact and spreads them on the surface, dispersing and adhering them substantially uniformly, and is the manufacturing apparatus for an electret fiber sheet according to (1).

[0013] (6) The spray nozzle is provided at a position where the generated water droplets are directly adhered to one surface of the fiber sheet, and the adhering means is provided on the downstream side of the fiber sheet in the conveying direction from the spray nozzle and is a blowing means for blowing air onto one surface of the fiber sheet. The air blown by the blowing means spreads the water droplets directly adhered to one surface on the surface, dispersing and adhering them substantially uniformly, and is the manufacturing apparatus for an electret fiber sheet according to (1).

[0014] The manufacturing apparatus for an electret fiber sheet according to (7), wherein the spraying means comprises a spraying nozzle that sprays flat air extending in the width direction of the fiber sheet as the air.

Advantages of the Invention

[0015] According to the manufacturing apparatus for an electret fiber sheet of the present invention configured as described above, by sucking in a state where water droplets are adhered to the fibers as water droplets or a film of water in a substantially uniform manner without aggregating the water droplets by the adhesion means, water can be passed through the inside of the fibers, the distribution of the water passing through the entire fibers also becomes uniform, and an electret fiber sheet that is sufficiently electretized without causing significant damage to the fibers can be provided.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0017] Next, embodiments of the present invention will be described in detail based on the accompanying drawings.

[0018] As shown in Fig. 1, the manufacturing apparatus 1 of the electret fiber sheet according to the present invention includes a conveying means 2 for conveying a fiber sheet 9, a water droplet generating means 3 including a spray nozzle 31 for generating water droplets, and an adhesion means 4 for dispersing and adhering water composed of the water droplets generated by the water droplet generating means 3 substantially uniformly onto one surface 9a of the fiber sheet 9 being conveyed by the conveying means 2, and a suction means 5 provided at a position corresponding to the adhesion means 4 on the other side of the fiber sheet 9, for sucking the water substantially uniformly dispersed and adhered onto one surface 9a of the fiber sheet 9 by the adhesion means 4 and allowing the water to penetrate and pass through the fiber sheet 9.

[0019] As the fiber sheet 9, known fiber sheets such as non-woven fabrics, woven fabrics, and knitted fabrics can be widely used, and a meltblown non-woven fabric frequently used as a filter is preferable. Further, the conveying means 2 is preferably a mesh conveyor belt. The mesh belt is not particularly limited as long as it is breathable, such as a cloth or a net.

[0020] Also, as long as it is breathable, it may be in a form other than a conveyor belt, such as a roller conveyor. It is not particularly limited as long as it enables suction by the suction means.

[0021] For example, when the fiber sheet 9 is a meltblown non-woven fabric, a collector composed of a conveyor of a meltblown non-woven fabric manufacturing apparatus may be used as the conveying means, or it may be an unsupported air conveyance (for example, one with several support rollers provided in the middle) between the collector and the winder. By providing it on the manufacturing line of the fiber sheet in this way, efficient continuous production can be achieved.

[0022] As shown in Fig. 1, the water droplet generating means 3 sends pure water stored in a water storage tank to the spray nozzle 31 by a pump, and mist-like water droplets are sprayed from the spray nozzle 31. The spray nozzle 31 is preferably one that sprays fine water droplets such as a spray nozzle, an atomizing nozzle, or an ultrasonic nebulizer.

[0023] A plurality of spray nozzles 31 are provided at intervals along the entire width of the fiber sheet 9 so as to be able to spray water droplets evenly in the width direction. The water droplets supplied from the spray nozzles 31 do not damage the fibers and are sprayed evenly. Since they are in the form of atomized water droplets, only a small amount of water is required, energy loss is small, and drying is also facilitated.

[0024] The suction means 5 is composed of a suction box 50 that sucks the water dispersed and adhered onto one surface 9a of the fiber sheet 9 from the side of the other surface 9b (back surface) of the fiber sheet 9. The suction box 50 is depressurized by a vacuum pump 51, and sucks the water on the fiber sheet 9 through a suction slit 50d extending along the entire width of the fiber sheet 9, and allows it to penetrate and pass through the fiber sheet 9. The fiber sheet 9 is charged during the process of adhesion, penetration, and passage of this water.

[0025] The adhesion means 4 is composed of various contact bodies 6 and air spraying means 41 described later, etc., and adheres the water composed of the water droplets generated by the water droplet generating means 3 onto the fiber sheet 9 in the form of a water film with a substantially uniform thickness or in a state where the water is distributed substantially uniformly as fine water droplets without aggregating significantly. By sucking in this state with the suction means 5, the water is uniformly dispersed, penetrated, and passed through the entire non-woven fabric. The adhesion means 4 includes various embodiments. First, the first embodiment will be described.

[0026] In the first embodiment, as shown in FIGS. 2 to 4, the spray nozzles 31 are provided at positions where the generated water droplets are directly adhered to the one surface 9a of the fiber sheet 9. And the adhesion means 4 is provided on the conveyance downstream side of the fiber sheet 9 with respect to the spray nozzles 31, and is composed of a contact body 6 that contacts the one surface 9a of the fiber sheet.

[0027] The contact body 6 adheres the water droplets directly attached to one surface 9a in a state where they are spread substantially uniformly by spreading them on the surface 9a including the aggregated water droplets. The suction means 5 (suction slit 50d) is positioned at the position on the back surface corresponding to the position of the fiber sheet surface 9a in contact with the contact body 6, and is configured to suck from the back in the spreading state.

[0028] The contact surface 6a of the contact body 6 that contacts one surface 9a of the fiber sheet 9 is preferably composed of a hydrophilic layer. Thereby, the water droplets adhering to one surface 9a can be more surely captured and spread in the substantially uniform state.

[0029] More specifically, the contact body 6 includes various examples. As a typical example, as shown in FIG. 2, it is a rotating roller 61 that rotates in synchronization with the fiber sheet 9, or as shown in FIG. 3, it is an endless belt 62 that moves in synchronization with the fiber sheet 9. As shown in FIG. 4, there is a cantilever flexible sheet 63 that is supported at one end on the upstream side in the conveyance direction and whose downstream side is in frictional contact with the fiber sheet 9.

[0030] The one configured with the rotating roller 61 as shown in FIG. 2 is one in which the rotating roller 61 extending over the entire width of the fiber sheet 9 is installed so as to contact one surface 9a of the fiber sheet 9. The contact with the fiber sheet 9 is a linear contact along the width direction. The suction slit 50d of the suction means 5 is positioned at the position on the back side (the other surface 9b) corresponding to this contact position. It may be driven in synchronization with the mesh belt of the conveyance means 2 by a motor, or may be configured as a roller that is not driven and is rotatably supported freely and rotates in synchronization by the frictional force of contact with the fiber sheet 9.

[0031] Since what drives has little friction with the fiber sheet 9, it is preferable to use a driving roller if the fiber sheet 9 is likely to be damaged. The roller surface is preferably a porous body, and the material is more preferably hydrophilic as described above. It is not necessary to press against the fiber sheet 9, and it is sufficient if the water droplets on the fiber sheet can be pushed. Therefore, the rotating shaft is supported at an appropriate vertical position according to the thickness of the fiber sheet 9.

[0032] In addition, what is constituted by the endless belt 62 as shown in FIG. 3 is an endless belt 62 having a width equal to or greater than the width of the fiber sheet 9, and the outer surface of the belt on the side facing the fiber sheet 9 is installed so as to be in surface contact with the fiber sheet 9. The contact with the fiber sheet 9 is a surface contact, and the suction slit 50d of the suction means 5 is positioned at an appropriate position on the back side (the other surface 9b) corresponding to this contact area. By driving the rotating roller that supports the endless belt 62 with a motor, the endless belt 62 may be moved in the same direction at the same speed in synchronization with the mesh belt of the conveying means 2, or it may be supported between free rollers without being driven and configured to move in synchronization by the frictional force of the contact with the fiber sheet 9.

[0033] Similar to the case of the above-mentioned rotating roller 61, since what drives has little friction with the fiber sheet 9, it is preferable to use a driving endless belt if the fiber sheet 9 is likely to be damaged. The belt surface is preferably a net, a woven fabric, a non-woven fabric or a porous body, and the material is more preferably hydrophilic as described above.

[0034] In addition, what is constituted by the cantilever flexible sheet 63 as shown in FIG. 4 is a flexible sheet 63 having a width equal to or greater than the width of the fiber sheet 9, and one end is supported at a position on the upstream side in the conveying direction (and at a position downstream of the spray nozzle 31), and the downstream side is provided so as to be in surface contact while rubbing against the fiber sheet 9. The flexible sheet 63 is preferably a net, a woven fabric, a non-woven fabric or a porous body, and the material is more preferably hydrophilic as described above.

[0035] The water droplets on the fiber sheet 9 are spread by the self-weight of the flexible sheet 63 and are dispersed and adhered in a substantially uniform manner. Such a flexible sheet 63, depending on the amount of water droplets being sprayed, is always in a state where a water film is formed on the downstream portion in surface contact with the fiber sheet 9.

[0036] Next, as shown in FIG. 5, in the second embodiment, the adhering means 4 is composed of a rotating roller 61 that contacts one surface 9a of the fiber sheet 9 and rotates in synchronization with the fiber sheet 9, and the spray nozzle 31 is provided at a position where the generated water droplets are adhered to the outer peripheral surface 61a of the rotating roller 61. The rotating roller 61 transfers the water droplets adhered to the outer peripheral surface 61a onto one surface 9a of the fiber sheet 9 in contact, spreads them on the surface, and disperses and adheres them in a substantially uniform manner.

[0037] In this example, before the water droplets adhere to one surface 9a of the fiber sheet 9 from the spray nozzle 31, they first adhere to the outer peripheral surface 61a of the rotating roller 61, which is then transferred to the surface 9a of the fiber sheet 9, spread, and dispersed and adhered. According to this, compared with the method of first adhering water droplets to the surface 9a of the fiber sheet to form aggregated water droplets and then homogenizing them, although it depends on the type of fiber sheet, it is possible to more reliably disperse and adhere them.

[0038] The rotating roller 61 extends over the entire width of the fiber sheet 9 and is installed so as to contact one surface 9a of the fiber sheet 9. The contact with the fiber sheet 9 is a linear contact along the width direction. The suction slit 50d of the suction means 5 is positioned at the position on the back side (the other surface 9b) corresponding to this contact position. It may be driven in synchronization with the mesh belt of the conveying means 2 by a motor, or may be configured as a roller that is freely rotatably supported without being driven and rotates in synchronization by the frictional force of contact with the fiber sheet 9. The roller surface is preferably a porous body, and the material is more preferably hydrophilic as in the first embodiment.

[0039] Next, as shown in FIG. 6, in the third embodiment, the adhering means 4 is an endless belt 62 that contacts the one surface 9a of the fiber sheet 9 and moves synchronously with the fiber sheet 9. The spray nozzle 31 is provided at a position where the generated water droplets are attached to the outer peripheral surface 62a of the endless belt. The endless belt 62 contacts and transfers the water droplets attached to the outer peripheral surface 62a onto the one surface 9a of the fiber sheet 9, and at the same time spreads them on the surface and disperses and attaches them substantially uniformly.

[0040] In this example as well, similar to the second embodiment, once the water droplets are attached to the outer peripheral surface 62a of the endless belt 62, they are transferred to the surface 9a of the fiber sheet 9, spread, and dispersed and attached. Compared with the case where water droplets are attached to the surface 9a of the fiber sheet first to form aggregated water droplets and then homogenized, although it depends on the type of fiber sheet, it is possible to more reliably disperse and attach them.

[0041] The contact with the fiber sheet 9 is a surface contact, and the suction slit 50d of the suction means 5 is positioned at an appropriate position on the back side (the other surface 9b) corresponding to this contact area. Similar to the first embodiment, the endless belt 62 may be moved in the same direction at the same speed synchronously with the mesh belt of the conveying means 2 by driving the rotating roller that supports the endless belt 62 by a motor, or it may be supported between free rollers without being driven and configured to move in synchronization by the frictional force of contact with the fiber sheet 9. The surface of the belt is preferably a net, a woven fabric, a non-woven fabric, or a porous body, and the material is more preferably hydrophilic as described above.

[0042] Next, as shown in FIG. 7, in the fourth embodiment, the spray nozzle 31 is provided at a position where the generated water droplets are directly attached to the one surface 9a of the fiber sheet 9, and the attaching means 4 is provided on the conveyance downstream side of the fiber sheet 9 with respect to the spray nozzle 31 and includes a blowing means 41 that blows air onto the one surface 9a of the fiber sheet 9. The air blown by the blowing means 41 spreads the water droplets directly attached to the one surface 9a on the surface and dispersedly attaches them substantially uniformly. The suction slit 50d of the suction means 5 is positioned at an appropriate position on the back side (the other surface 9b) corresponding to the region of the surface 9a of the fiber sheet onto which this air is blown.

[0043] The blowing means 41 includes a blowing nozzle that blows flat air extending in the width direction of the fiber sheet 9 as air. The flat air is preferably in the form of a curtain that is blown uniformly. According to this example, a curtain of air is created, the water droplets sent together with the fiber sheet 9 are spread by the air and dispersedly attached, and the water is pushed into the fibers together with the suction force of the suction means 5 and can be efficiently passed through.

[0044] Although the embodiments of the present invention have been described above, the present invention is not limited to such examples at all, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Description of Reference Numerals

[0045] 1 Manufacturing apparatus for electret fiber sheet 2 Conveying means 3 Water droplet generating means 4 Attaching means 5 Suction means 6 Contact body 6a Contact surface 8 Aggregated water droplets 9 Fiber sheet 9a, 9b Surfaces 31 Spray nozzle 41 Blowing means 42c Gap 50 Suction box 50d Suction slit 51 Vacuum pump 61 Rotating roller 61a Outer peripheral surface 62 Endless belt 62a Outer peripheral surface 63 Cantilever flexible sheet

Claims

1. Conveying means for conveying a fiber sheet, Water droplet generating means comprising a spray nozzle for generating water droplets, Adhering means for substantially uniformly dispersing and adhering water composed of water droplets generated by the water droplet generating means onto one surface of the fiber sheet being conveyed by the conveying means, Suction means provided at a position corresponding to the adhering means on the other side of the fiber sheet, for sucking the water substantially uniformly dispersed and adhered onto one surface of the fiber sheet by the adhering means and allowing the water to penetrate and pass through the fiber sheet, A manufacturing apparatus for an electret fiber sheet comprising the above.

2. The spray nozzle is provided at a position for directly adhering the generated water droplets onto one surface of the fiber sheet, and The adhering means is provided on the conveyance downstream side of the fiber sheet with respect to the spray nozzle, and comprises a contact body that contacts one surface of the fiber sheet, By this contact body, the water droplets directly adhering to one surface are spread on the surface and substantially uniformly dispersed and adhered, The manufacturing apparatus for an electret fiber sheet according to Claim 1.

3. The contact body comprises a rotating roller that rotates in synchronization with the fiber sheet, an endless belt that moves in synchronization with the fiber sheet, or a cantilever flexible sheet that is supported at one end on the upstream side in the conveyance direction and whose downstream side is in frictional contact with the fiber sheet, The manufacturing apparatus for an electret fiber sheet according to Claim 2.

4. The adhering means comprises a rotating roller that contacts one surface of the fiber sheet and rotates in synchronization with the fiber sheet, The spray nozzle is provided at a position for adhering the generated water droplets onto the outer peripheral surface of the rotating roller, By this rotating roller, the water droplets adhering to the outer peripheral surface are contact-transferred onto one surface of the fiber sheet and at the same time spread on the surface and substantially uniformly dispersed and adhered, The manufacturing apparatus for an electret fiber sheet according to Claim 1.

5. The adhering means comprises an endless belt that contacts one surface of the fiber sheet and moves in synchronization with the fiber sheet, The spray nozzle is provided at a position for adhering the generated water droplets onto the outer peripheral surface of the endless belt, By this endless belt, the water droplets adhering to the outer peripheral surface are contact-transferred onto one surface of the fiber sheet and at the same time spread on the surface and substantially uniformly dispersed and adhered, The manufacturing apparatus for an electret fiber sheet according to Claim 1.

6. The spray nozzle is provided at a position where the generated water droplets are directly attached to the one surface of the fiber sheet, and the attaching means is provided on the conveyance downstream side of the fiber sheet with respect to the spray nozzle, and comprises a blowing means for blowing air onto the one surface of the fiber sheet, the air blown by the blowing means spreads the water droplets directly attached to the one surface on the surface and disperses and attaches them substantially uniformly, The manufacturing apparatus for an electret fiber sheet according to claim 1.

7. the blowing means comprises a blowing nozzle that blows flat air extending in the width direction of the fiber sheet as the air, The manufacturing apparatus for an electret fiber sheet according to claim 6.

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