JP2005169239A - Application method to flexible band article and applicator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for controlling defects such wrinkles and stretch produced by the accumulation of unevenness in thickness in rewinding a coating sheet provided with a coated film on a flexible band article in the state of a roll. <P>SOLUTION: The application method of applying on the flexible band article continuously running between carrier guides is provided. The method is characterized by applying reciprocating a coating portion perpendicularly to the running direction of the flexible band article while keeping not to make the flexible band article shake in the width direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a coated sheet and an apparatus therefor, in which a coating film is formed by coating a coating on one or both sides of a long and wide flexible strip.

  Examples of the application sheet having the coating film include a magnetic recording medium in which a magnetic layer is formed by applying a magnetic coating on at least one surface of a flexible belt (hereinafter also referred to as a base film), and a base film. There are photographic films coated with a photosensitive emulsion on the surface, functional films coated with an optical thin film on the surface of a base film, and the like. Examples of the method for applying the paint to the base film include a roll coater method, a gravure coat method, a roll coat plus doctor method, an extrusion type application method, and the like. Any method other than the method is applicable.

  Hereinafter, in the description of this type of prior art, a case where a magnetic recording medium in which a magnetic paint is applied to the surface of a base film by using an extrusion coating method will be described as an example. In addition, as an extrusion type coating apparatus, a non-contact type that forms a coating film between gap gaps between a backup roll and a coater head, a contact type that forms a film by winding a base film directly around the coater head In addition, the coater head may be of any type having one or more slit gaps and capable of forming one or more layers simultaneously.

  As shown in FIG. 1, the coating method of the magnetic coating material for the magnetic recording medium according to the prior art is such that the base film is unwound by the unwinding unit 10 and continuously traveled between the guide rollers 11 for conveyance guide. Previously, the base film traveling position was controlled to a predetermined fixed position by an edge positioning unit 12 (hereinafter abbreviated as EPC), and a magnetic coating was applied to the surface of the base film that had traveled without meandering using the coating unit 20. After that, the magnetic coating is dried by the drying unit 14 to form a magnetic layer, and the winding position of the obtained coated sheet is controlled again by the EPC 12 before winding the coated sheet, without causing the coated sheet to meander. In general, the winding unit 13 controls the edge of the base film at the same position in the laminating direction and winds the film into a raw fabric. Similarly, a back coat paint is applied on the back surface. Application to the front and back surfaces of these base films may be performed in a batch using two coating apparatuses with the same equipment, or may be performed with another apparatus.

  In such an extrusion-type coating apparatus, uneven coating thickness in the width direction of the base film (hereinafter also referred to as coating unevenness) due to the effect of the slit gap accuracy, which is the paint discharge portion of the die head, and various other precisions. Tended to occur. FIG. 2 is a schematic diagram of coating unevenness 1 generated by the extrusion type coating apparatus, and shows a cross section in the width direction of the coating sheet.

  In the method of manufacturing a magnetic recording medium according to the above-described prior art, since the edges of the base film are wound at the same position in the stacking direction and wound into a raw fabric, the coating unevenness generated by the extrusion type coating apparatus is stacked. The original fabric wound up to a predetermined length has a problem of being undesirably rolled up in terms of shape defects such as deformation of the original fabric and wrinkles as shown in FIG.

  Further, in the magnetic recording medium in the original fabric state of FIG. 3, there are packing defects in the next calendar (surface smoothing) process, poor width accuracy in the cutting process to obtain a predetermined tape width, and poor tape runnability. There was a problem that the yield of the finished magnetic tape deteriorated.

  As means for solving the coating unevenness inherent in the position of the base film in the width direction in the coating device, the base film or a coating device that performs coating while swinging the die (Patent Document 1), the base film in the width direction. A method for manufacturing a magnetic recording medium in which coating is performed while rocking at a predetermined period is disclosed in Patent Document 2.

JP-A-7-284710 JP-A-8-332440

  However, in the method of applying the base film disclosed in Patent Document 1 and Patent Document 2 while swinging in the width direction at a predetermined cycle, in the drying process after applying the paint, the paint is applied to the base film. The coated sheet is run while meandering in a drying oven that dries at a high temperature, and is subjected to thermal shrinkage unevenly in the width direction of the coated sheet, and the width of the base film in a cycle in which the base film is swung during coating. Tension difference tends to occur in each direction. Even if an application sheet in which the difference in tension is generated is used to restrict the running position using EPC before being wound into the original fabric, the base film is not suitable for winding into the original due to the difference in tension. The coating unevenness tends to exist at the same position of the winding. As a result, it eventually winds up in an undesirable state in terms of shape defects. In addition, the fact that the base film is swung at a predetermined cycle by EPC upstream of the coating part is likely to cause disturbance in the coating film thickness distribution in the width direction due to the tension difference in the width direction given by EPC.

  Even in an apparatus that performs coating while swinging the die, which is disclosed in Patent Document 1, the base film also swings slightly with the swing of the die due to the viscosity of the paint. For this reason, the above-described problem due to the swing of the base film occurs. This tendency is particularly great when a thin base film having a thickness of 12 μm or less is used.

  The present invention eliminates the drawbacks of the prior art described above, and prevents the coating unevenness caused by the coating apparatus from being generated at the same place in the width direction of the wound original fabric, and is wound into a raw fabric. An object of the present invention is to provide a method and apparatus for producing a long original fabric having a coating film with reduced shape defects.

  In order to achieve the above object, the present inventors have conducted intensive studies, and as a result, applied to a flexible strip that continuously travels between conveyance guides. The coating portion is applied while reciprocating at a right angle to the traveling direction of the flexible belt-like object while being held so as not to shake.

  As described above, according to the present invention, when applying a paint to the base film, the coating device itself is swung linearly with respect to the base film, so that the slit gap of the die head in the extrusion type coating device. Even if coating unevenness that is affected by precision and other processing accuracy of the die occurs, these coating unevenness does not occur in the same part in the width direction of the base film, and the coated sheet with the base film coated with paint Because it does not swing in the width direction, it travels in a certain position without meandering in the drying furnace, so there is no uneven tension in the width direction due to thermal deformation, and the coated sheet is wound in the same position in the width direction. Can be taken. For this reason, even if it winds up in the shape of a raw fabric, since it can be in the winding state as shown in FIG. 8, generation | occurrence | production of the shape deformation | transformation of the coating original fabric by the coating nonuniformity can be suppressed significantly.

  In addition to the magnetic recording medium described above, the present invention is also applicable to a photographic film in which a photosensitive emulsion is coated on the surface of the base film, a functional film in which an optical thin film is coated on the surface of the base film, and the like. As a coating method, it can be applied to an extrusion type coating method using a die head and a gravure coating method in which a base film is nipped and coated, and a backup roll and a coater head in various types of extrusion type coating apparatuses. A non-contact type that forms a coating film between the gap gap and a contact type that forms a film by winding a base film directly around the coater head, and the coater head has one or more slits The same applies to a system having a gap and capable of simultaneously forming one or more multilayers.

  According to the present invention, when the coating is applied to the base film, the coating portion of the coating device is periodically swung in the width direction, so that the coating unevenness affected by the processing accuracy of the die head in the extrusion type coating device and others. Even if this occurs, these coating unevenness does not occur in the same part of the base film, and since the base film has means for holding it so as not to swing in the width direction, Since the belt travels in a certain position without meandering, non-uniform tension in the width direction due to thermal deformation does not occur, and the coated sheet can be wound up at the same position in the width direction. For this reason, even if it winds up in the shape of an original fabric, generation | occurrence | production of the shape deformation of the coating original fabric by the coating nonuniformity can be suppressed significantly.

  In addition, in Patent Document 1 and Patent Document 2, there is no description about the optimum type of oscillation, but the present inventors have intensively studied this point, for example, as shown in FIG. 2 of Patent Document 2. In such a swing mechanism, the swing trajectory with respect to the base film has a sine wave shape (FIG. 6), and the time when the coater is positioned in the vicinity of both ends of the swing range in time is located in other portions. It has been found that streaky coating unevenness cannot be sufficiently uniformly diffused because it is longer than the time. That is, it is preferable that the time for which the coater exists in any position in the swing range is equal for the swing. For this purpose, the swing trajectory with respect to the base film is a linear zigzag shape (FIG. 7). Has been found to be preferable.

  As a means for holding the base film so as not to swing in the width direction, a suction roller, a grooved roller, or the like can be used as the swing suppression roller, but other conventionally known methods may be used.

  Hereinafter, the present invention will be described in more detail based on examples using a magnetic recording medium manufacturing apparatus as an example, but it is needless to say that the present invention is not limited to these examples.

  FIG. 4 is a conceptual diagram of an apparatus for applying a magnetic coating material on a magnetic recording medium, which is an embodiment of a manufacturing apparatus for a long original fabric having a coating film according to the present invention, and FIG. 5 is an application apparatus shown in FIG. It is the schematic diagram which showed one specific example of the rocking device. FIG. 8 is a schematic diagram of the raw magnetic recording medium showing the coating unevenness generated by the magnetic paint applying device in the magnetic recording medium shown in FIG.

  First, with reference to FIG. 4 and FIG. 5, the coating device of the magnetic coating material in the magnetic recording medium of this invention is demonstrated. The magnetic paint applying device for the magnetic recording medium includes the same configuration device as the magnetic paint applying device for the magnetic recording medium of the prior art shown in FIG. , The EPC unit 12, the coating unit 20, the drying unit 14, the winding unit 13, and the swinging unit 30 of the coating unit 20 that swings the coating apparatus characterized by the present invention at a predetermined cycle and swinging width. Has been.

  In order to avoid duplication, only the configuration of the swinging portion of the coating apparatus will be described below. First, the coating unit 20 is attached to a support block 32 on a linear guide 31 installed in a direction perpendicular to the traveling direction of the base film, and is smoothly and only in a direction perpendicular to the traveling direction of the base film (the X direction in the drawing). It can be swung without shaking. Further, the groove cam 36 is rotated by the rotational power of the drive motor 37 and the rotary motion is performed by the lever 34 in order to give the coating portion attached as described above to swing in the direction perpendicular to the traveling direction of the base film. It is converted into a rocking motion and is configured to rock the application part. Here, the swing width and motion curve of the swing motion are determined by the design of the groove cam 36, and the swing cycle is determined by the rotation cycle of the drive motor. The groove cam 36 is designed so that the application unit 20 moves at a constant speed, and draws a linear zigzag locus as shown in FIG. Although the groove cam has been described as an example of the swinging means of the coating apparatus, the present invention is not limited to this, and any mechanism can be used as long as the coating head can swing periodically. . The coating is performed while the die is swung. By providing the rocking restraining roller 21 in front of and behind the die, the fine swing of the base film caused by the viscosity of the paint is caused by the rocking of the die. The coating is performed while restraining, and the base film after coating is wound into a raw fabric without meandering. As the rocking suppression roller, a conventionally known roller such as a suction roller or a grooved roller can be used.

The results of applying the magnetic recording medium using this apparatus will be described below.
The base film uses a PET film with a thickness of 6 μm and a width of 1000 mm, and is applied with an extrusion type coating apparatus so that the coating thickness after drying is 2.5 μm. Created.

  First, as the oscillating motion curve of the coating apparatus, as a result of examining the sinusoidal motion shown in FIG. 6 and the linear motion shown in FIG. 7, as a result of observing the shape of the wound surface of the rolled up raw material, the linear motion of FIG. It was found that the effect on the coating unevenness is greater, and that the linear motion is preferable as the swinging motion of the coating device.

  Next, examination was performed in the range of a rocking width of 1 to 100 mm and a rocking cycle of 5 to 500 m (base film travel distance per cycle). The rocking motion curve was a linear motion. Table 1 shows the quality judgment results of the original fabric state for each swing width and swing cycle. In the table, ◯ indicates a good state where no coating unevenness is observed, Δ indicates a state where slight unevenness is observed, and × indicates a state where large coating unevenness is observed. Thus, if the oscillation width is increased, the effect on coating unevenness is increased. However, if the swinging width is too large, the uncoated portions at both ends of the base film must be enlarged. Also, if the oscillation period is too large, coating unevenness tends to be laminated at the same position in the width direction of the original fabric in some wound layers (several hundreds to thousands of layers) in the original fabric state. The coating unevenness is diffused, but after cutting into the tape width, it is divided into the length required for the product and wound. The effect of diffusing unevenness cannot be obtained at all. Further, when a normal guide roller was used instead of the rocking suppression roller, coating unevenness remained a little. From the above, it is preferable to set the swing width in the range of 5 to 50 mm practically, and the swing period is preferably smaller than the winding length in the product (cartridge, cassette, etc.). Is preferably in the range of 5 to 100 m. It can also be seen that it is preferable to use a rocking suppression roller. However, these conditions are determined in more detail by the relationship between the width of the base film to be used and the coating width, as well as the width of the coating unevenness and the core diameter of the winding web, and are optimal and appropriate. It is preferable to carry out.

*) Although the applicator was rocked, a normal guide roller was used instead of the rocking suppression roller.

It is a conceptual diagram of the coating apparatus of the magnetic coating material of the magnetic recording medium as an example of the manufacturing apparatus of the articles | goods which consist of base films by a prior art. It is a schematic diagram of the coating nonuniformity which arose by the extrusion type coating device. FIG. 2 is a schematic diagram of an original fabric rolled up in an unfavorable state in terms of shape defects such as original deformation and wrinkles generated by the coating method shown in FIG. 1. It is a conceptual diagram of an example of the coating device of the magnetic coating material in the magnetic recording medium which is one Example of the manufacturing apparatus of the articles | goods consisting of the base film of this invention. It is the schematic diagram which showed one specific example of the rocking | fluctuation apparatus of the coating device shown in FIG. It is a schematic diagram of the sinusoidal movement in rocking | fluctuation of a coating device. It is a schematic diagram of the linear motion in rocking | fluctuation of a coating device. FIG. 5 is a schematic diagram of an original magnetic recording medium showing coating unevenness generated by a magnetic paint coating apparatus in the magnetic recording medium shown in FIG. 4.

Explanation of symbols

1 coating unevenness 2 base film 3 coating film 10 unwinding part 11 guide roller 12 EPC
DESCRIPTION OF SYMBOLS 13 Winding part 14 Drying part 20 Application | coating apparatus 21 Oscillation suppression roller 30 Oscillation apparatus 31 Linear guide 32 Support block 33 Connecting bar 34 Oscillation arm 35 Cam follower 36 Groove cam 37 Drive motor

Claims (2)

  A method of applying on a flexible strip that continuously travels between conveyance guides, and holding the flexible strip so that it does not sway in the width direction. A coating method for a flexible strip, wherein the coating is performed while reciprocating at right angles to the traveling direction. A coating apparatus that performs coating on a flexible strip that continuously travels between conveyance guides, and in the coating section, a means for holding the flexible strip so as not to swing in the width direction, and a coating section. And a means for continuously reciprocating the flexible belt in the direction perpendicular to the traveling direction.

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