JP2023105944A - Manufacturing method and manufacturing apparatus of multilayer film - Google Patents

Abstract

To provide a manufacturing method and manufacturing apparatus of a multilayer film which can impregnate a porous body with coating liquid while accurately forming a coating film on both surfaces of the porous body with any physical property.SOLUTION: A manufacturing method of a multilayer film comprises the steps of: forming a first coating film by applying the first coating liquid to one surface of a sheet-like support body that is continuously conveyed; laminating a sheet-like porous body on the first coating film in such a state that the first coating film is undried; forming a second coating film by applying the second coating liquid to a surface on a side that is not in contact with the first coating film of the porous body in such a state that the first coating film is undried, discharging the second coating liquid from a die having a discharge surface formed with a slit-like discharge port, applying the second coating liquid while curving or bending the support body 1 and a porous body 3 by pressing the discharge surface against the porous body via the second coating liquid and impregnating the porous body with at least one of the first coating film and the second coating film; and simultaneously drying the first and second coating films.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a multilayer film in which coating films are formed on both sides of a porous body, and in particular to a method for producing a multilayer film capable of efficiently impregnating a coating liquid, regardless of the physical properties of the porous body. It relates to manufacturing equipment.

Multilayer films, which are made by forming coating films on both sides of sheet-like porous materials such as non-woven fabrics, cloth, fibers, mesh, paper, and sponge, can be used in applications such as fiber-reinforced plastics (prepreg), release paper, airbags, battery separators, electrodes, etc. Used in various fields. In these methods, it is required to impregnate the porous body with the coating liquid while accurately applying the coating liquid to both surfaces of the porous body.

As a method of impregnating the porous body with a coating liquid while forming coating films on both sides of the porous body, for example, as in Patent Document 1, a coating die is installed on both sides of the porous body while the porous body is conveyed. A method of application by pressing is disclosed.

JP 2016-36761 A

However, in the method disclosed in Patent Document 1, since the coating is performed by pressing the coating die while the porous body is conveyed alone, it is necessary to apply a high tension to the porous body. Porous bodies with low strength, such as thin porous bodies and porous bodies with a high porosity, have problems of elongation, wrinkles, and breakage.

Therefore, the present invention provides a method and method for producing a multilayer film capable of impregnating a porous body with a coating liquid while accurately forming coating films on both sides of the porous body, regardless of the physical properties of the porous body. Provide equipment.

The method for producing a multilayer film according to the present invention for solving the above problems includes:
a step of applying a first coating liquid to one surface of a continuously conveyed sheet-like support to form a first coating;
Next, a step of laminating a sheet-like porous body on the first coating film while the first coating film is undried;
Next, while the first coating film is undried, a second coating liquid is applied to the surface of the porous body that is not in contact with the first coating film to form a second coating film. wherein the second coating liquid is discharged from a die having a discharge surface formed with slit-shaped discharge ports, and the discharge surface is pressed against the porous body through the second coating liquid. By applying the second coating liquid while curving or bending the support and the porous body, the porous body is impregnated with at least one of the first coating film and the second coating film. and
and then drying the first and second coatings simultaneously.

The apparatus for manufacturing a multilayer film of the present invention for solving the above-mentioned problems includes:
a support conveying device for continuously conveying a sheet-shaped support;
a first coating device that applies a first coating liquid to one surface of the support that is continuously transported by the transport device to form a first coating film;
A porous body supply device that continuously supplies a sheet-like porous body so as to laminate the porous body on the first coating film downstream of the first coating device in the conveying direction. and,
A second coating liquid is applied to the surface of the porous body that is not in contact with the first coating film on the downstream side in the conveying direction of the position where the porous body is laminated to form a second coating film. a second coating device that forms a
a drying device that simultaneously dries the first and second coating films on the downstream side in the conveying direction of the second coating device,
The second coating device is a die having a discharge surface with a slit-shaped discharge port formed thereon, and has a support that sandwiches the support and supports the support from the side opposite to the discharge surface. First, the second coating liquid is applied while pressing the discharge surface against the porous body.

According to the method and apparatus for producing a multilayer film of the present invention, a high tension is imparted to the porous body by transporting the support and the porous body to which tension is applied while adhering them via the first coating film. It can be conveyed without stretching, and the elongation, wrinkles, and breakage of the porous body can be prevented. Furthermore, by forming the second coating film while pressing the ejection surface of the die against the porous body, the effect of pushing the coating liquid into the porous body can be obtained, and the porous body can be efficiently impregnated with the coating liquid. can. As a result, regardless of the physical properties of the porous body and the coating liquid, the coating liquid can be impregnated into the porous body while forming the coating film on both sides with high accuracy, and the productivity of the multilayer film is improved. improve greatly.

It is a schematic diagram showing a method of manufacturing a multilayer film according to one embodiment of the present invention. FIG. 2 is a detailed cross-sectional view enlarging the tip portion A of the die 4 of the embodiment of FIG. 1; It is a schematic sectional drawing which shows the manufacturing method of the multilayer film of another embodiment of this invention. It is a schematic diagram showing a manufacturing method of a multilayer film of another embodiment of the present invention. It is a schematic sectional drawing which shows the manufacturing method of the multilayer film of another embodiment of this invention. 7 is a diagram showing an example of an observation field of view of camera 8 in the embodiment of FIG. 6. FIG. FIG. 4 is a perspective view showing the inclination of the die 4 with the rotation axis being the direction in which the support is conveyed.

Preferred embodiments of the invention are described below. It should be noted that the following description exemplifies the embodiments of the invention, and the present invention is not to be construed as being limited thereto, and various modifications are possible without departing from the object and effect of the present invention. .

FIG. 1 is a schematic diagram showing a method for manufacturing a multilayer film according to one embodiment of the present invention. In the method for producing a multilayer film of the present embodiment, the first film is formed on one surface of the support 1 transported by the support transporting device comprising the support unwinding device 11, the winding device 61, and a plurality of transport rollers. A first coating liquid is discharged from the coating device 2 to form a first coating film (not shown), and then the first coating film is in an undried (unhardened) state. A sheet-like porous material 3 continuously supplied from a porous material supply device 31 is laminated thereon. Next, while the first coating film is undried, the surface of the porous body 3 not in contact with the first coating film (upper surface in FIG. 1) is coated with the die 4, which is the second coating device. A second coating is formed by ejecting a second coating liquid. At this time, while the support 1 is not supported from the opposite side of the die 4, the second coating liquid is discharged from the die 4 having a slit-shaped discharge port at the tip, and the die 4 is discharged through the second coating liquid. By forming the second coating film while the ejection surface is pressed against the porous body 3 to bend or bend the support 1 and the porous body 3, the first coating film or the first coating film and the second coating film are formed. The porous body 3 is impregnated with both coating films. Finally, the drying device 5 dries (or solidifies) the first coating film and the second coating film at the same time to form the multilayer film 6 , which is wound up by the winding unit 61 .

In the method for producing a multilayer film of the present embodiment, the porous body 3 is adhered via the first coating film to the support 1 which is conveyed under tension by the support conveying device. 3 can be conveyed without applying high tension. At this time, the porous body 3 only needs to be given the minimum tension for conveying it from the porous body supply device 31 to the lamination roller 32 . As a result, even porous bodies that are prone to wrinkles, elongation, and breakage, specifically, porous bodies that are thin, have high porosity, and have low material strength, do not cause wrinkles, elongation, and breakage. can be stably transported without

Next, the effect of the die 4 will be explained. FIG. 2 is a detailed cross-sectional view enlarging the tip portion A of the die 4 of the embodiment of FIG. A first coating film 101 and a porous body 3 are laminated on the support 1 , and a slit-shaped discharge port 41 is opened at the tip of the die 4 . The second coating liquid discharged from the discharge port 41 is applied to the surface of the porous body 3 while forming the coating liquid reservoir 7 between the tip of the die 4 and the porous body 3 to form a second coating film. form 102; At this time, the tip of the die 4 is pressed against the porous body 3, the first coating film 101, and the support 1 via the coating liquid reservoir 7, and high pressure is generated in the coating liquid reservoir 7. FIG. This pressure has the effect of impregnating the porous body 3 with the second coating film 102 and the effect of impregnating the porous body 3 pushed into the coating liquid reservoir 7 with the first coating film 101. impregnates the porous body 3 efficiently. In particular, when it is difficult for the porous body 3 to naturally impregnate the first coating film 101 due to capillary force, gravity, or the like, the viscosity of the coating liquid is high, the affinity between the coating liquid and the porous body is low, Even if the impregnation time is short, the porous body 3 can be efficiently impregnated with the coating liquid. As a result, a laminate of the support 1, the first coating film 101, the porous body 103 sufficiently impregnated with the coating liquid, and the second coating film 102 can be obtained.

In addition, since the support 1 is not supported from the opposite side of the die 4, the support 1 and the porous body 3 are bent by the pressing force of the die 4. If the pressing force is large, the support 1 and the porous body 3 are bent. It will be in a bent state.

Even if a support roller or the like is provided at a position facing the die 4 with the support 1 interposed therebetween, and the tip of the die 4 is brought close to the support 1 while the support 1 is not curved or bent, the coating liquid is discharged. Since a high pressure is generated in the coating liquid pool 7, the porous body 3 can be impregnated with the coating liquid. However, when the support roller is eccentric, the gap between the tip of the die 4 and the porous body 3 fluctuates due to the effect of the eccentricity. Not only does the liquid impregnation state become unstable, but in some cases, the tip of the die 4 and the porous body 3 come into contact with each other, causing the porous body 3 to wrinkle, stretch, or break. Alternatively, if the support 1 has unevenness in thickness, the unevenness in thickness directly leads to variations in the gap between the tip of the die 4 and the porous body 3, which causes similar problems. Therefore, it is preferable not to provide a support roller at a position facing the die 4 with the support 1 interposed therebetween. In order to stabilize the transportation of the support 1 , when support rollers are provided, it is preferable to provide them on the upstream side or downstream side of the die 4 , avoiding the position facing the die 4 across the support 1 .

The material and shape of the support 1 are not particularly limited, and any material that can support and transport the porous body 3, such as a resin film such as a PET film or a metal foil, may be used.

The material and shape of the porous body 3 are also not particularly limited, and non-woven fabric, cloth, fiber, mesh, paper, sponge, and the like can be used.

The type of coating liquid is not particularly limited, and a solution obtained by dissolving a polymer in a solvent, a thermosetting/light-curing liquid polymer, a slurry, an emulsion, or the like can be used. Also, the first coating liquid and the second coating liquid may be the same or different. The first coating liquid and the second coating liquid are different, the second coating liquid is more likely to impregnate the porous body, and the force for pressing the discharge surface of the die 4 against the porous body 3 is weak, so that the support 1 and the porous body If the degree of bending or bending of the body 3 is small, the porous body may not be impregnated with the first coating liquid, and only the second coating liquid may impregnate the porous body.

The coating method of the coating unit 2 is not particularly limited, either, and various coating methods such as die, spray, bar, blade, knife, comma, and dip can be selected. The material of the die 4 is also not particularly limited, and metals such as stainless steel, ceramics, resins, and the like can be used.

In this embodiment, the drying device 5 is used as an example of a method for solidifying the coating film, but the invention is not limited to this, and any device that can solidify the coating film may be used. For example, if the coating liquid is a photocurable liquid polymer, an exposure device can be used instead of the drying device 5 .

FIG. 3 is a schematic cross-sectional view showing a method of manufacturing a multilayer film according to another embodiment of the present invention, and is an enlarged view of a tip portion A of a die corresponding to the die 4 in FIG. The support 1, the first coating film 101 and the porous body 3 are transported in the X direction in FIG. Hereinafter, unless otherwise specified, the conveying direction means the conveying direction X of the support 1 . In the embodiment of FIG. 3, of the ejection surface of the die 4, the portion 42 on the upstream side in the transport direction from the ejection port 41 is recessed in the direction away from the porous body 3 from the portion 43 on the downstream side in the transport direction. .

In the present embodiment, the corner portion B of the portion 42 on the upstream side in the transport direction of the ejection surface of the die 4 is less likely to come into contact with the porous body 3 without passing through the coating liquid reservoir 7. It is possible to prevent the porous body 3 from being scratched, wrinkled, or broken during formation, and improve the quality of the multilayer film 6 .

At this time, the size of the step H between the portion 42 on the upstream side in the transport direction and the portion 43 on the downstream side in the transport direction is not particularly limited, and is determined according to the state of the porous body 3 and the state of formation of the second coating film 102. do it. The larger the step H between the portion 42 on the upstream side in the transport direction and the portion 43 on the downstream side in the transport direction, the more difficult it is for the portion 42 on the upstream side in the transport direction to come into contact with the porous body 3. overflows further upstream than the upstream portion 42 in the conveying direction, and the thickness of the second coating film 102 becomes unstable.

FIG. 4 is a schematic diagram showing a method of manufacturing a multilayer film according to another embodiment of the present invention, and is a view of a die corresponding to the die 4 in FIG. 2 or 3 as seen from the Y direction. In the embodiment of FIG. 4, the support 1, the first coating 101, the porous body 103, and the second coating 102 are transported in the front direction of the page. A dashed line 44 in the die 4 indicates the discharge flow path of the coating liquid, and the length of the discharge port (not shown) in the width direction of the support 1 is W, that is, the coating width of the second coating film is W. be. Further, of the ejection surface of the die 4, the portion 43 on the downstream side of the ejection port in the conveying direction is the both side portions 43b outside the coating width W, and the porous body 103 is more porous than the portion 43a inside the coating width W. pulls away from

In this embodiment, of the portion 43 on the downstream side in the transport direction of the ejection surface of the die 4, the portion 43b where the second coating film 102 is not formed is less likely to come into contact with the porous body 103. It is possible to prevent the porous body 3 from being scratched, wrinkled, or broken during formation, and improve the quality of the multilayer film 6 .

At this time, the step between the portion 43a inside the coating width W and the portion 43b outside the coating width W of the portion 43 on the downstream side in the conveying direction is not particularly limited, and may be determined according to the state of the porous body 3. Just do it. Similarly to the portion 43 on the downstream side in the conveying direction, the portion 42 on the upstream side in the conveying direction is also a portion on both sides outside the coating width W, and is further away from the porous body 3 than the portion on the inside of the coating width W. Recessing is preferable from the viewpoint of preventing scratches, wrinkles, and breakage of the porous body.

FIG. 5 is a schematic cross-sectional view showing a method of manufacturing a multilayer film according to another embodiment of the present invention. In the embodiment of FIG. 5, the ejection surface is observed by a camera 8 from a position facing the ejection surface of the die 4 with the support 1 interposed therebetween. The depth of pressing the ejection surface of the die 4 against the porous body 3 in the Z direction of FIG. . Specifically, when the second coating liquid reservoir 7 formed between the ejection surface and the porous body 3 does not completely cover the ejection port 41 within the observation field of view, the ejection surface of the die 4 is It is sufficient to press the porous body 3 deeper.

FIG. 6 shows an example of the observation field of view of the camera 8 in this embodiment. FIG. 6A shows an example in which the second coating liquid reservoir 7 formed between the ejection surface and the porous body 3 completely covers the ejection port 41 within the observation field. In FIG. 6, the dashed line 81 indicates the field of view of the camera, the area 41 of the arrow in the ejection surface of the die 4 is the ejection port, the area 42 of the arrow is the portion on the upstream side in the conveying direction, the area 43 of the arrow is the portion on the downstream side in the conveying direction, The painted area represents the coating liquid reservoir 7, and the support, first coating film 101, and porous body 3 are omitted for the sake of simplicity. The support is transported in the X direction in FIG. In the example of FIG. 6( a ), the coating liquid pool 7 completely covers the discharge port 41 of the die 4 , and the interface 71 on the upstream side of the coating liquid pool 7 in the transport direction is upstream of the discharge port 41 in the transport direction. positioned. Next, FIG. 6B shows an example in which the second coating liquid reservoir 7 formed between the ejection surface and the porous body 3 does not completely cover the ejection port 41 within the observation field. A portion of the interface 71 on the upstream side in the transport direction of the coating liquid reservoir 7 overlaps the ejection port 41 .

When the field of view 81 is in the state of FIG. 6B, air bubbles enter the discharge port 41 of the die 4 from the interface 71 on the upstream side in the conveying direction of the coating liquid pool 7, and air bubbles and coating streaks appear on the second coating film 102. occurs. When the observation field of view 81 is in the state of FIG. 6(b), the ejection surface of the die 4 is deeply pressed against the porous body 3 until the state of FIG. Air bubbles and coating streaks of 102 can be eliminated, and the quality of the multilayer film can be improved. Further, even when the observation field 81 is in the state shown in FIG. By pressing deeply against the second coating film 102, the interface 71 on the upstream side in the transport direction of the coating liquid reservoir 7 can be kept away from the ejection port 41, and the occurrence of air bubbles and coating streaks in the second coating film 102 can be prevented, which is more preferable.

Furthermore, it is more preferable to observe the entire coating width direction of the ejection surface of the die 4 by installing a plurality of cameras 8 in the coating width direction of the die 4 or by scanning the cameras 8 in the coating width direction of the die 4 . Specifically, the depth of pressing the ejection surface of the die 4 against the porous body 3 and the conveying direction of the support are set as the rotation axis so that the coating liquid reservoir 7 completely covers the ejection port 41 in the coating width direction. By adjusting the inclination of the die 4 as shown in FIG. Here, the inclination of the die 4 with the direction of transport of the support as the axis of rotation represents the state of rotation of the die 4 in the direction of arrow R when the direction of transport of the support 1 is X in FIG.

INDUSTRIAL APPLICABILITY The method and apparatus for producing a multilayer film of the present invention can be widely applied to various uses such as fiber-reinforced plastics (prepreg), release paper, airbags, battery separators, and electrodes.

Reference Signs List 1 support 2 first coating device 3 porous body 4 die (second coating device)
5 Drying Device 6 Multilayer Film 7 Second Coating Liquid Pool 8 Camera 11 Support Unwinding Device 31 Porous Body Feeding Device 32 Laminating Roller 41 Discharge Port 42 Portion 43 of the discharge surface of the die upstream of the discharge port in the conveying direction , 43a, 43b portion of the ejection surface of the die on the downstream side in the conveying direction from the ejection port 44 ejection channel 61 of the die winding device 71 interface 81 on the upstream side of the second coating liquid pool observation field of view 101 of the camera the first Coating film 102 Second coating film 103 Porous body A impregnated with coating liquid Tip of die B Corner H of portion on the upstream side in the conveying direction Step R Direction of die inclination (rotational direction)
W coating width of the second coating film X conveying direction of the support Z pressing direction of the die

Claims (7)

a step of applying a first coating liquid to one surface of a continuously conveyed sheet-like support to form a first coating;
Next, a step of laminating a sheet-like porous body on the first coating film while the first coating film is in an undried state;
Then, while the first coating film is undried, a second coating liquid is applied to the surface of the porous body that is not in contact with the first coating film to form a second coating film. wherein the second coating liquid is discharged from a die having a discharge surface formed with slit-shaped discharge ports, and the discharge surface is pressed against the porous body via the second coating liquid. By applying the second coating liquid while curving or bending the support and the porous body, the porous body is impregnated with at least one of the first coating film and the second coating film. and
then simultaneously drying the first and second coatings;
A method for producing a multilayer film having In the step of impregnating the porous body with at least one of the first coating film and the second coating film, the first coating film or both the first coating film and the second coating film 2. The method for producing a multilayer film according to claim 1, wherein the porous body is impregnated with 2. The die used is such that the ejection surface is recessed in a direction away from the porous body at a portion on the upstream side in the conveying direction from the ejection port and from a portion on the downstream side in the conveying direction. 2. The method for manufacturing a multilayer film. As the die, a portion of the ejection surface downstream in the conveying direction from the ejection port is located at both end portions outside the ejection port in the coating width direction, and is farther from the porous body than portions other than the end portions. 4. The method of manufacturing a multilayer film according to any one of claims 1 to 3, wherein the recessed parts are used. Observing the ejection surface from a position facing the ejection surface of the die with the support interposed therebetween,
The ejection surface is pressed against the porous body so that the pool of the second coating liquid formed between the ejection surface and the porous body completely covers the ejection port within the observation field. adjust the depth,
The method for producing a multilayer film according to any one of claims 1 to 4. Observing the whole of the ejection surface in the coating width direction from a position facing the ejection surface of the die with the support interposed therebetween,
The rotation axis is defined by the depth at which the ejection surface is pressed against the porous body and the transport direction of the support so that the pool of the second coating liquid completely covers the ejection port in the coating width direction. adjusting the tilt of the die,
A method for producing a multilayer film according to claim 5. a support conveying device for continuously conveying a sheet-shaped support;
a first coating device that applies a first coating liquid to one surface of the support that is continuously transported by the transport device to form a first coating film;
A porous body supply device that continuously supplies a sheet-like porous body so as to laminate the porous body on the first coating film downstream of the first coating device in the conveying direction. and,
A second coating liquid is applied to the surface of the porous body that is not in contact with the first coating film on the downstream side in the conveying direction of the position where the porous body is laminated to form a second coating film. a second coating device that forms a
a drying device that simultaneously dries the first and second coating films on the downstream side in the conveying direction of the second coating device,
The second coating device is a die having a discharge surface with a slit-shaped discharge port formed thereon, and has a support that sandwiches the support and supports the support from the side opposite to the discharge surface. First, the second coating liquid is applied while pressing the ejection surface against the porous body.
Multilayer film manufacturing equipment.

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