JPWO2019088052A1 - Web manufacturing method, charge control method and charge control device - Google Patents

Abstract

For example, a web having a controlled amount of charge is manufactured without previously applying an electric charge to the web such as a long polymer film. In a method of manufacturing a web including a transport process for transporting the web, a liquid is supplied to the interface between the transport roll that transports the web and the web, and the amount of charge generated on the surface of the web due to triboelectric charging between the transport roll and the web is controlled. To do. As the liquid, for example, a liquid is used in which triboelectric charging having a polarity opposite to the charging polarity generated on the surface of the web due to triboelectric charging between the transport roll and the web is generated between the web and the web.

Description

The present invention relates to a method for manufacturing a web having a controlled amount of charge, a charge control method for controlling the amount of charge on the web, and a charge control device.

In general, static electricity is generated when two substances rub against each other, and one of the two substances is relatively positively charged and the other is negatively charged. The tendency of a substance to be positively or negatively charged when it rubs against another substance is commonly known as a charged sequence for each substance, and by reference to the charged sequence, any two. It is possible to estimate which is positively charged when triboelectric charging occurs between substances. An example of a charged train is shown in Non-Patent Document 1.
For example, when transporting a web such as a long polymer film, the web is moved by rotating the transport roll while supporting the web by the transport roll, and static electricity is also generated between the web and the transport roll. Will occur and the surface of the transported web will be charged. When the amount of charge on the surface of the web becomes large, a peeling discharge may occur between the web and the transport roll at a position where the web transported by the transport roll separates from the transport roll (referred to as a roll peeling point). As a result, discharge marks are formed on the surface of the web, which becomes a defect in the web. For example, when the web is coated, the discharge marks cause uneven coating. Further, even if the peeling discharge does not occur, there is a problem that various kinds of dust are likely to adhere to the charged surface.

As a technique for eliminating the charge generated on the surface of the web due to triboelectric charge, there is a technique using a static eliminator that generates ions that neutralize the surface charge in the air. However, when a static eliminator is used, a space for providing the static eliminator is required, and the static eliminator may not be installed depending on the structure around the transport roll. Since the static eliminator generates ions by electric discharge, the static eliminator cannot be placed even in an environment that requires explosion protection. Further, when the transport speed of the web is high or the distance from the roll peeling point to the static eliminator is large, the static elimination capacity may be insufficient and static elimination may not be sufficient. Further, since the transport roll is generally made of metal and has conductivity, the static elimination ions are absorbed by the transport roll and the static elimination capacity is lowered. If the surface of the web is not uniformly charged but mottled, the apparent charging potential will be low, and it may not be possible to sufficiently eliminate static electricity.

In Patent Document 1, a substance that is positively charged and a substance that is negatively charged by triboelectric charging with the web are alternately arranged in the transport direction of the web to form a transport roll, whereby the transport roll is formed. Above, it discloses that the web is not charged.
Patent Document 2 discloses that a charge having the opposite polarity to the triboelectric charge is applied to the surface of the web opposite to the surface charged by friction, and the charge of the triboelectric charge is neutralized by the charge having the opposite polarity. are doing.
Patent Document 3 discloses that an electric charge having a polarity opposite to the polarity of triboelectric charging is previously applied to the surface of the web that comes into contact with the roll before it comes into contact with the roll.

Japanese Patent Application Laid-Open No. 62-131500 Japanese Patent No. 5858869 Japanese Patent Application Laid-Open No. 10-15812

Akinari Kasai, "Factors on Charge Measurements", Polymers, Polymer Society, 1967, Vol. 16, No. 179, p. 323-329

However, in the technique of Patent Document 1, since the web is charged when viewed microscopically, there is still a risk of peeling discharge, and it is not possible to positively control the amount of charge on the surface of the web. Have difficulty.
In the method of Patent Document 2, the sum of the electric charges on both the front and back surfaces is zero and it seems that they are not charged, but in reality, there is an electric charge on each surface, and this is, for example, a post-process coating. It causes uneven coating in the process. If one surface comes into contact with a metal roll and is grounded in a state where electric charges are present on both the front and back surfaces, a potential due to the electric charge on the other surface is generated, which may attract dust in the air.
In the method of Patent Document 3, since the web has a high potential before it comes into contact with the roll, there is a risk of adsorbing dust or causing an electric discharge when it comes into contact with the roll.

As described above, among the techniques for preventing charge on the web transported by the transport roll, the technique using the static eliminator may not be applicable, and the static elimination capacity may be insufficient. The technique described in Patent Document 1 may not sufficiently prevent peeling discharge. The techniques described in Patent Documents 2 and 3 preliminarily apply a charge having the opposite polarity to the charge due to triboelectric charging, but have problems such as adsorption of dust and generation of electric discharge due to the addition of electric charge. It can be said that preventing the charge of the web is a form of controlling the charge amount of the web, but a general technique for controlling the charge amount of the web by a method other than adding a charge is not known. ..

An object of the present invention is to provide a manufacturing method for manufacturing a web whose charge amount is controlled without applying a charge to the web in advance, and a charge control method and a charge control device for controlling the charge amount of the web. ..

The method for manufacturing a web of the present invention is a method for manufacturing a web including a transport step for transporting the web, in which a liquid is supplied to the interface between the transport roll for transporting the web and the web, and friction between the transport roll and the web is provided. It has a step of controlling the amount of charge generated on the surface of the web by charging.
The charge control method of the present invention is a charge control method for controlling the amount of charge of the web transported by the transport roll, and supplies a liquid to the interface between the transport roll that transports the web and the web to supply the transport roll and the web. Controls the amount of charge generated on the surface of the web by triboelectric charging with.
The charge control device of the present invention is a charge control device that controls the amount of charge of the transported web, and comprises a transport roll that transports the web and a supply means that supplies liquid to the interface between the transport roll and the web. The liquid controls the amount of charge generated on the surface of the web due to the triboelectric charge between the transport roll and the web.

Triboelectric charging can occur not only between solids, but also between solids and liquids. In the present invention, in order to control the amount of charge on the surface of the web after being conveyed by the transfer roll, a liquid for controlling the amount of charge is supplied to the interface between the transfer roll that conveys the web and the web. By controlling the amount of liquid supplied to the interface, the amount of charge generated on the surface of the web can be controlled. Since triboelectric charging also occurs between the web and the liquid, the amount of charging on the surface of the web can be controlled by combining the triboelectric charging between the web and the liquid with the triboelectric charging between the web and the transport roll. become. In particular, the charge on the surface of the web is reduced by using a liquid as the liquid that causes triboelectric charging between the web and the transport roll and the web, which has the opposite polarity to the charge polarity generated on the surface of the web. Or, charging can be prevented. What kind of liquid should be used may be determined based on the above-mentioned charged train according to the material of the web and the material of the surface of the transport roll. In addition, if the amount of liquid supplied to the interface between the transport roll and the web is changed, the magnitude of triboelectric charge generated between the web and the liquid also changes, so the amount of liquid supplied to the interface should be controlled. Therefore, finer control of the charge amount of the web can be performed.

In the present invention, the web is, for example, a long polymer film or an electrically insulating film. As a method of supplying the liquid to the interface between the transport roll and the web, the liquid may be directly supplied to the interface from the direction in which the web enters the interface, or the liquid may be supplied toward the surface of the rotating transport roll. It may be sprayed. The liquid sprayed on the surface of the transport roll is supplied to the interface between the transport roll and the web as the transport roll rotates. As a method of supplying the liquid, spraying can reduce the consumption of the liquid as compared with the method of directly supplying the liquid to the interface, and the supply amount can be finely controlled. Further, in order to control the amount of charge in the width direction of the web (the direction orthogonal to the transport direction), the transport roll is divided into a plurality of regions along the longitudinal direction of the transport roll, and the amount of liquid supplied is determined. It may be controlled for each divided area.

According to the present invention, it is possible to manufacture a web having a controlled amount of charge without applying a charge to the web in advance, and to control the amount of charge of the web.

FIG. 1 is a diagram showing a configuration of a charge control device according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration for controlling the charge amount of a wide web.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a charge control device according to an embodiment of the present invention. This charge control device is used when manufacturing a web by a manufacturing method based on the present invention.
The charge control device shown in FIG. 1 is configured to be usable in the process of transporting the web 10, and the transport roll 20 for transporting the web 10 and the position of the transport roll 20 in contact with the web 10 are defined. It is provided with a spray nozzle 30 arranged to face the surface of the transport roll 20 at a position opposite to that of the transfer roll 20.
Examples of the web 10 include, and are not limited to, a film for magnetic materials, a film for mold release, a film for capacitors, a film for battery separators, and the like. In particular, in the case of a film for a magnetic material, a film for a mold release, and a film for a battery separator, it is effective from the viewpoint of preventing uneven coating when the final product is obtained through the coating process. Further, in the case of a battery separator film in which foreign matter control is strict, it is effective from the viewpoint of preventing adhesion of dust and the like due to static electricity.
In the embodiment of the present invention, the transfer step has at least one rotating transfer roll, and utilizes the frictional force generated between the transfer roll and the web in a state where the transfer roll and the web are in contact with each other. This is the process of transporting the web. Separate rotating rolls may be provided before and after the transport roll for transport, or the end of the web may be gripped by a traveling clip or the like for transport.

The spray nozzle 30 is a sprayer that sprays the charge control liquid b onto the rotating transport roll 20, and functions as a supply means for supplying the charge control liquid b to the interface between the transport roll 20 and the web 10. To do. That is, the supply means may be a sprayer that sprays the liquid onto the rotating transport roll. A liquid b for charge control is supplied to the spray nozzle 30, and compressed air a is also supplied to spray the liquid b for charge control. The spray nozzle 30 is covered with a nozzle cover 40 in order to prevent the liquid b for charge control from scattering at an unintended position. The nozzle cover 40 is formed with a slit 41 extending in the longitudinal direction of the transport roll 20 at a position facing the transport roll 20, and the charge control liquid b sprayed from the spray nozzle 30 has the slit 41. It passes through and reaches the transport roll 20. The width of the slit 41 (the length along the rotation direction of the transport roll 20) can be adjusted within the range of, for example, 10 mm to 30 mm, and the gap (gap) between the position of the slit 41 and the surface of the transport roll 20. ) Is, for example, about 2 mm. With one spray nozzle 30, spraying can be performed on a region of, for example, about 30 cm in the longitudinal direction of the transport roll 20.

Further, in the charge control device shown in FIG. 1, an electrometer 50 for measuring the surface potential of the surface of the web 10 in contact with the transport roll 20 is arranged at a position downstream of the transport roll 20 in the transport direction of the web 10. Has been done. The electrometer 50 is not essential, but as will be clarified from the examples described later, the surface potential of the web 10 changes depending on the supply amount of the liquid b for charge control, and the charge amount changes. Therefore, the electrometer 50 changes. By providing 50 and controlling the supply amount of the liquid b for charge control by the measured value, the charge amount of the web 10 can be controlled more accurately. The surface of the web 10 transported downstream from the transport roll 20 may be wet with the charge control liquid b, and the charge control liquid b may be, for example, air-blown, heat-dried, or nip-rolled. It can be removed by scraping off.

Next, control of the amount of charge using this charge control device will be described. When the transfer roll 20 is rotated to convey the web 10 while spraying the charge control liquid b from the spray nozzle 30 toward the transfer roll 20, the sprayed charge control liquid b becomes the web 10 and the transfer roll 20. It will be continuously supplied to the interface of. As a result, triboelectric charging occurs between the transport roll 20 and the web 10, and triboelectric charging also occurs between the supplied liquid and the web 10. If these two triboelectric charges have the same polarity with respect to the web 10, the absolute value of the surface potential of the web 10 increases and the charge amount of the web 10 increases. If the polarity is opposite, the charge due to triboelectric charge between the transport roll 20 and the web 10 is neutralized by the triboelectric charge between the charge control liquid b and the web 10, and the charge is controlled. If the triboelectric charge between the liquid b and the web 10 is of an appropriate magnitude, they cancel each other out and the charge amount of the web 10 becomes extremely small. Therefore, according to the charge control device of the present embodiment, the charge amount of the web 10 can be controlled, and in particular, triboelectric charging having a polarity opposite to the charge polarity generated on the surface of the web due to frictional charging between the transport roll and the web is performed. If the liquid generated between the web and the web is used as the liquid b for charge control and the supply amount is controlled, the charge amount of the web 10 can be made almost zero.

What is used as the liquid b for charge control can be determined based on the charge train according to the target charge amount and the material of the web 10, considering the material of the surface of the transport roll 20. It is preferable to select the web 10 within a range that does not change the properties of the web 10. For example, when the web 10 is made of a polyethylene film, examples of the surface material of the transport roll 20 that easily causes positive triboelectric charging include silicon rubber and hard chrome plating, and as a liquid that easily causes negative triboelectric charging. For example, water and the like. On the other hand, examples of the surface material of the transport roll 20 that easily causes negative triboelectric charging on the polyethylene film include glass, and examples of the liquid that easily causes positive triboelectric charging include trichlorobenzene and dichloromethane. Halogen-based solvent can be mentioned.

The width of the web 10 (that is, the direction orthogonal to the transport direction) may be wider than the width at which the liquid b for charge control can be sprayed from one sprayer as the supply means. In such a case, if only one atomizer is used, only a part of the web 10 can be controlled. FIG. 2 shows the arrangement of the sprayer (spray nozzle 30) in the charge control device corresponding to the wide web 10. For the sake of clarity, Web 10 is not shown in FIG.

Similar to the one shown in FIG. 1, the charge control device shown in FIG. 2 sprays the charge control liquid b from the spray nozzle 30 so that the charge control liquid b is sprayed on the interface between the web 10 and the transport roll 20. Is supplied to control the amount of charge of the web 10. Here, it is assumed that water is used as the liquid b for charge control. Assuming that the length of the transport roll 20 is longer than the width of the web 10, in the charge control device shown in FIG. 2, a plurality of spray nozzles 30 (here, three) as sprayers are prepared, and a single nozzle cover is provided. These spray nozzles 30 are arranged in the 40 in the longitudinal direction of the transport roll 20. The air a used for spraying water is commonly supplied to the plurality of spray nozzles 30. The slit 41 of the nozzle cover 40 is provided so as to face the transport roll 20 and extend over substantially the entire length of the transport roll 20 in the longitudinal direction. In the illustrated example, the transport roll 20 is divided into three regions (each region of L, C, and R shown) along the longitudinal direction thereof. The water used for spraying is supplied via the pressure reducing valve 31, is branched into three pipes 32 to 34 on the outlet side of the pressure reducing valve 31, and a spray nozzle 30 is provided at the tip of each of the pipes 32 to 34. Has been done. The pipes 32 to 34 correspond to the area L, the area C, and the area R, respectively, and each includes a valve 35 and a flow meter 36.

In the one shown in FIG. 2, by controlling the valve 35, when the transport roll 20 is divided into a plurality of regions in the longitudinal direction thereof, the amount of water supplied can be controlled for each divided region. It will be possible. This makes it possible to control the amount of charge in the width direction of the web 10. In particular, since the flow meter 36 is provided corresponding to each of the area L, the area C, and the area R, the opening degree of the valve 35 is controlled based on the measured value by the flow meter 36. It becomes possible to control the charge amount with high accuracy for each of the region C and the region R.

Hereinafter, the present invention will be described in more detail with reference to Examples.
[Example 1]
The device shown in FIG. 1 was assembled. Here, a soft polyethylene sheet (manufactured by Kokugo Co., Ltd.) having a thickness of 30 μm was used as the web 10, and a metal roll having a diameter of 150 mm and having a hard chrome-plated surface was used as the transport roll 20. As the spray nozzle 30 which is a sprayer, a two-fluid nozzle manufactured by Ikeuchi Co., Ltd., model number: SCBIMV80005S was used. Tap water was used as the liquid b for charge control, and the tap water and air a were supplied to the spray nozzle 30 so that water could be sprayed on the transport roll 20. The transport roll 20 was rotated to transport the web 10 at 30 m / min. Then, the surface potential of the web 10 was measured by an electrometer 50 provided on the downstream side of the transport roll 20 while changing the presence or absence of water spray and the water spray flow rate. The results are shown in Table 1.
From Table 1, the surface potential of the web 10 is about +15 kV, which is positive when water is not sprayed, but the surface potential may change in the negative direction by spraying water. I understand. When the spray flow rate of water was 7 mL / min, the surface potential decreased to about + 8 kV, and when the spray flow rate was 11 mL / min, the surface potential was almost 0 kV. That is, by setting the water spray flow rate to 10 to 12 mL / min, triboelectric charging of the web 10 can be prevented. When the spray flow rate was further increased to 16 mL / min, the surface potential could be lowered to -17 kV. It has been found that the surface potential of the web 10, that is, the amount of charge can be controlled by controlling the spray flow rate, that is, the amount of water supplied to the interface between the transport roll 20 and the web 10.

[Example 2]
A glass-coated roll was used as the transport roll 20, and 1,2,4-trichlorobenzene was used as the liquid b for charge control. Other than these, the same procedure as in Example 1 was carried out. The results are shown in Table 2. From Table 2, the surface potential of the web 10 is about -9 kV, which is negative when the liquid is not sprayed, but the surface potential can be changed in the positive direction by spraying the liquid. I understand. When the spray flow rate of the liquid was 10 mL / min, the surface potential shifted to the positive side to be about -5 kV, and when the spray flow rate was 15 mL / min, the surface potential was almost 0 kV. That is, by setting the spray flow rate of the liquid to 14 to 16 mL / min, triboelectric charging of the web 10 can be prevented. When the spray flow rate was further increased to 20 mL / min, the surface potential could be shifted to + 8 kV. It was found that even when the web 10 is negatively charged due to triboelectric charging with the transport roll 20, the charge amount of the web 10 can be controlled by controlling the flow rate of the liquid that causes triboelectric charging.

According to the present invention, a web manufacturing method, a charge control method, and a charge control device capable of manufacturing a web in which the charge amount is controlled without applying a charge to the web in advance and capable of controlling the charge amount of the web are provided. provide.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on October 30, 2017 (Japanese Patent Application No. 2017-209140), the contents of which are incorporated herein by reference.

10 Web 20 Conveying roll 30 Spray nozzle 40 Nozzle cover 50 Electrometer a Air b Liquid for charge control w Water

Claims (13)

A method of manufacturing a web that includes a transport process for transporting the web.
A manufacturing method comprising a step of supplying a liquid to the interface between a transport roll for transporting the web and the web, and controlling the amount of charge generated on the surface of the web by triboelectric charging between the transport roll and the web. The production according to claim 1, wherein the liquid is a liquid that causes triboelectric charging having a polarity opposite to the charging polarity generated on the surface of the web due to triboelectric charging between the transport roll and the web. Method. The manufacturing method according to claim 1 or 2, wherein the amount of charge generated on the surface of the web is controlled by controlling the amount of the liquid supplied to the interface. The manufacturing method according to claim 3, wherein the transport roll is divided into a plurality of regions along the longitudinal direction of the transport roll, and the amount of the liquid is controlled for each of the divided regions. It is a charge control method that controls the charge amount of the web transported by the transfer roll.
A charge control method in which a liquid is supplied to the interface between a transport roll for transporting a web and the web, and the amount of charge generated on the surface of the web due to triboelectric charging between the transport roll and the web is controlled. The charging according to claim 5, wherein the liquid is a liquid that causes triboelectric charging having a polarity opposite to the charging polarity generated on the surface of the web due to triboelectric charging between the transport roll and the web. Control method. The charge control method according to claim 5 or 6, wherein the charge amount generated on the surface of the web is controlled by controlling the amount of the liquid supplied to the interface. The charge control method according to claim 7, wherein the transport roll is divided into a plurality of regions along the longitudinal direction of the transport roll, and the amount of the liquid is controlled for each of the divided regions. A charge control device that controls the amount of charge on the transported web.
A transport roll that transports the web and
A supply means for supplying a liquid to the interface between the transport roll and the web,
Have,
A charge control device that controls the amount of charge generated on the surface of the web by the triboelectric charge between the transport roll and the web with the liquid. The charge according to claim 9, wherein the liquid is a liquid that causes triboelectric charging having a polarity opposite to the charge polarity generated on the surface of the web by triboelectric charging between the transport roll and the web. Control device. The charge control device according to claim 9 or 10, wherein the charge amount generated on the surface of the web is controlled by controlling the amount of the liquid supplied to the interface by the supply means. The charge control device according to claim 11, wherein the transport roll is divided into a plurality of regions along the longitudinal direction of the transport roll, and the supply means is provided for each of the divided regions. The charge control device according to any one of claims 9 to 12, wherein the supply means is a sprayer that sprays the liquid onto the rotating transport roll.

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