JP5416617B2 - Coating system and coating method - Google Patents

Description

  The present invention relates to a coating system and a coating method, and more particularly, to a coating system and a coating method for coating a coating solution on a long flexible support that runs continuously.

  Optical films such as photographic light-sensitive materials, magnetic recording media, optical compensation films, antireflection films, and antiglare films are coated with a coating solution on a long flexible support (hereinafter referred to as “web”) that runs continuously. It is manufactured through an application process in which a coating film is formed by application. In the coating process, coating methods such as gravure coating, bar coating, slide coating, extrusion coating, and curtain coating are employed.

  In the coating process described above, regardless of the coating method, thick coating portions of the coating film are generated at both edges in the width direction of the web due to the surface tension of the coating solution. Since this thick coating part causes unevenness of drying in the subsequent drying process, it is desired to remove the thick coating part before the drying process. As a method for removing thick coating portions at both edges in the width direction of the web, Patent Document 1 discloses a method of sucking a thick coating portion with a suction nozzle.

JP-A-7-299410

  By the way, about the thick coating part, the shape differs with the difference in an application | coating system. For example, in a coating method represented by slide coating, extrusion coating, etc., a coating solution that has been measured in advance so as to have a predetermined coating amount is supplied to the web. In such a coating method, thick coating portions having a uniform thickness are generated at both edges in the width direction of the web. The thick coating portion having a uniform thickness can be uniformly removed using the suction method of Patent Document 1.

On the other hand, in a coating method represented by gravure coating, bar coating, etc., an excessive coating solution is fed by a pump, and then the coating amount is measured. In such a coating method, thick coating portions having a non-uniform thickness are generated at both edges in the width direction of the web. If the thick-coated portion having a non-uniform thickness is removed using the suction method of Patent Document 1, the thick-coated portion having a non-uniform (periodic ) thickness cannot be removed uniformly, and a part of the thick-coated portion may be removed. It may wrap around the back of the web. If the suction amount is increased in order to prevent the above-described back side, all of the coating liquid at both edges in the width direction of the web may be sucked. In either case, since both ends of the web cannot be used as a product, both ends of the web must be cut. For this reason, the entire width direction of the web could not be effectively made, resulting in web loss.

  This invention is made | formed in view of such a situation, and it aims at providing the coating system and coating method which can remove reliably the thick coating part which generate | occur | produces at the both ends of a web.

  According to one aspect of the present invention, a coating system that forms a coating film by supplying a coating liquid to a continuously running support, a coating system coating apparatus that feeds an excessive coating liquid and then measures the coating amount; A leveling member that is arranged downstream of the coating device and that makes a thick coating portion of the coating film at the end in the width direction of the support constant, and an end in the width direction of the support that is arranged downstream of the leveling member And a suction device for removing a part of the coating film.

  According to the coating system of the present invention, after the thick coating portion is adjusted to a certain thickness by the leveling member, a part of the coating film is removed by the suction device. Thereby, the thick coating part which generate | occur | produces at the both ends of a web can be removed reliably.

  According to another aspect of the present invention, the leveling member is preferably a flat plate made of a polymer material having a thickness of 0.3 mm or less. If the thickness of the flat plate is too thick, the coating film formed by coating may be scraped off and the support may be scratched. Therefore, the thickness of the flat plate is preferably 0.3 mm or less.

  According to another aspect of the present invention, it is preferable that the leveling member is a brush having a wire diameter of 0.3 mm or less. If the wire diameter of the brush is thick, the coating film formed by application may be scraped off and the support may be scratched. Accordingly, the brush wire diameter is preferably 0.3 mm or less.

  According to another aspect of the present invention, the leveling member is tilted by a predetermined angle or more with respect to a direction orthogonal to the traveling direction of the support, and the surface of the leveling member is arranged to face inward with respect to the traveling direction of the support. It is preferable. It is preferable that the leveling member is inclined at least 5 degrees with respect to a direction orthogonal to the traveling direction of the support.

  Since the surface of the leveling member is arranged so as to face the inner side with respect to the traveling direction of the support, the excess liquid scraped off by the leveling member is guided to the center side of the support. That is, the excess liquid in the thick coating portion does not flow out to the outside of the support. It is possible to prevent surplus liquid from flowing around the back surface of the support. Since the surplus liquid does not go around the back surface of the support, it is possible to prevent the roll supporting the back surface of the support from being contaminated.

  According to another aspect of the present invention, the coating device is preferably at least one of a gravure coating device and a bar coating device.

  According to another aspect of the present invention, the gravure roll of the gravure coating apparatus or the bar of the bar coating apparatus has an inclination of 15 degrees or more and 60 degrees or less with respect to a direction orthogonal to the center axis of the gravure roll or the bar. It is preferable to have a spiral groove.

  According to another aspect of the present invention, a step of supplying a coating liquid to a continuously running support by a coating device of a post-metering coating method to form a coating film, and a leveling member disposed downstream of the coating device, The coating of the widthwise end of the support is performed by a leveling process in which the thick coating portion of the coating at the widthwise end of the support is made constant and a suction device disposed downstream of the leveling member. And a step of removing a part of the film.

  According to the coating system and the coating method of the present invention, thick coating portions generated at both ends of the web can be reliably removed.

The conceptual diagram which shows the whole structure containing the coating system of this Embodiment. The conceptual diagram which shows the positional relationship of the structure of this Embodiment. Sectional drawing which shows the structure of a suction nozzle. Schematic explaining the effect | action of a leveling member. The conceptual diagram of the gravure coating apparatus used for the coating system of this Embodiment. The conceptual diagram of the bar coating apparatus used for the coating system of this Embodiment. Front view of the bar.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention will be described with reference to the following preferred embodiments, but can be modified in many ways without departing from the scope of the present invention, and other embodiments than the present embodiment can be used. be able to. Accordingly, all modifications within the scope of the present invention are included in the claims. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to”.

  FIG. 1 is a schematic configuration diagram of a coating system. The coating system 10 includes a coating device 16 that supplies a coating liquid 14 to the web 12 to form a coating film, a leveling member 18 that is disposed downstream of the coating device 16, and a suction nozzle 20 that is disposed downstream of the leveling member 18. Is provided. A pass roller 22 is disposed at a position facing the suction nozzle 20. The web 12 is guided from the coating device 16 to the suction nozzle 20 by a guide roller 24.

  A suction tube 26 is connected to the suction nozzle 20. The suction pipe 26 is connected to an exhaust tank 30 via an exhaust pipe 28. A vacuum pump 32 is connected to the exhaust tank 30.

  The suction nozzle 20 is connected to an ejection pipe 34 for the cleaning liquid. The ejection pipe 34 is connected to a cleaning water supply tank 38 via a cleaning water supply pipe 36.

  FIG. 2 is a diagram illustrating a positional relationship among the coating apparatus, the leveling member, and the suction nozzle. As shown in FIG. 2, the coating device 16 is disposed on the upstream side in the traveling direction of the web 12. When the web 12 passes through the coating device 16, the coating liquid is supplied to the web 12, and the coating film 40 is formed in the entire width direction of the web 12. At both end portions in the width direction of the web 12, thick coating portions 40A of the coating film 40 having a thickness greater than that of the central portion of the web 12 are simultaneously formed.

  The leveling member 18 is disposed at a position downstream of the coating device 16 where the thick coating portion 40A is formed. The leveling member 18 is tilted so that the angle (α) formed by the direction orthogonal to the traveling direction of the web 12 is 5 degrees or more. Thereby, the surface of the leveling member 18 is arranged so as to face inward with respect to the traveling direction of the web 12. Here, facing inward means that when the leveling member 18 is viewed upward, the inner end 18A of the leveling member 18 is located downstream of the outer end 18B of the leveling member 18 with reference to the traveling direction of the web 12. Means state. The suction nozzle 20 is disposed at a position downstream of the leveling member 18 where the thick coating portion 40A is formed.

  FIG. 3 is a cross-sectional view showing the structure of the suction nozzle 20. The suction nozzle 20 has a double tube structure. A jet pipe 34 is provided on the central axis of the double pipe. A plurality of jet outlets 34 </ b> A are provided at the tip of the jet pipe 34. The jet outlet 34 </ b> A is provided at a position facing the inner wall of the suction nozzle 20. This is to prevent the cleaning liquid supplied from the jet nozzle 34 </ b> A from being directly supplied to the thick coating portion 40 </ b> A of the coating film 40. A part of the thick coating portion 40 </ b> A is discharged from the suction tube 26 through the tip port 21 of the suction nozzle 20, passing between the inner wall of the suction nozzle 20 and the outer wall of the ejection tube 34.

  FIG. 4 is a conceptual diagram showing a state in which the thick coating portion 40A is leveled by the leveling member 18. As shown in FIG. A thick coating portion 40A having a non-uniform thickness is formed at both ends in the width direction of the web 12 that has passed through the coating apparatus. The thick coating portion 40A is leveled by the leveling member 18 to form a thick coating portion 40A having a constant thickness. As the leveling member 18, it is preferable to use a flat plate made of a polymer material having a thickness of 0.3 mm or less. If the thickness of the flat plate is too thick, the coating film formed by coating may be scraped off and the support may be scratched. Therefore, the thickness of the flat plate is preferably 0.3 mm or less.

  As a material of the leveling member 18, it is necessary that at least the tip portion is a flexible material. Specifically, it is difficult to modify with a solvent such as rubber, Teflon (registered trademark), triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and has a certain degree of bending. What has the property to be flexible is preferable. When rubber is used, it is preferable to perform coating such as urethane coating, Teflon (registered trademark), or silicon coating in order to improve the slipperiness and abrasion resistance against contact with the web 12. Further, it is possible to use a rubber material that is improved in slipping property and wear resistance by kneading Teflon (registered trademark), molybdenum, oil, or the like.

  Further, it is preferable to use a brush having a wire diameter of 0.3 mm or less as the leveling member 18. If the wire diameter of the brush is thick, the coating film formed by application may be scraped off and the support may be scratched. Accordingly, the brush wire diameter is preferably 0.3 mm or less. As a brush material, a material having high solvent resistance such as polyester or nylon can be used.

  Next, with reference to FIGS. 1-4, operation | movement of the coating system 10 of this Embodiment is demonstrated. First, the web 12 is continuously conveyed to the coating device 16 by a feeder (not shown). The coating liquid 14 is supplied to the web 12 by the coating device 16, and the coating film 40 is formed. At this time, thick coating portions 40 </ b> A are simultaneously formed at both ends in the width direction of the web 12. The thick coating portion 40A has a nonuniform (periodic) thickness, not a constant thickness.

  The web 12 is guided by the guide roller 24 and conveyed to the leveling member 18 to a position. A part of the thick coating portion 40A is scraped off by the leveling member 18, and the thick coating portion 40A has a constant thickness.

  Next, the web 12 is conveyed to the suction nozzle 20. The exhaust tank 30 is depressurized by the vacuum pump 32, and a part of the thick coating portion 40 </ b> A is sucked from the tip end 21 of the suction nozzle 20. The coating composition that constitutes a part of the thick coating portion 40 </ b> A is stored in the exhaust tank 30 via the suction pipe 26 and the exhaust pipe 28.

  The suction nozzle 20 is provided with an ejection pipe 34 for ejecting cleaning liquid on the central axis. When a part of the thick coating portion 40A is sucked, the cleaning liquid is ejected from the ejection port 34A of the ejection pipe 34. Thereby, the inside of the suction nozzle 20 can be washed and the inside of the suction nozzle 20 can be prevented from being blocked. The cleaning liquid used for cleaning the suction nozzle 20 is stored in the exhaust tank 30 through the suction pipe 26 and the exhaust pipe 28 together with a part of the thick coating portion 40A.

  According to the coating system of the present embodiment, thick coating portions generated at both ends of the web can be reliably removed.

  The coating system of this embodiment can also be used for the production of photosensitive materials such as photographic films, the production of magnetic recording materials such as recording tapes, and the production of coated metal thin plates such as colored iron plates. Accordingly, as a web to which the coating liquid can be applied, a web for an optical film such as a photographic photosensitive material, a magnetic recording medium, an optical compensation film, an antireflection film, an anti-glare film, or the like is sensitive to the surface on the conspicuous side of the web. Lithographic printing plate web with heat-sensitive plate-making surface, photographic film base material, photographic paper coating bar lighter paper, recording tape base material, video tape base material, floppy (registered trademark) disk base material, etc. And a base material having a continuous belt-like shape made of metal, plastic, paper, or the like.

  Moreover, as a coating liquid, the solution used for apply | coating to a web and drying and forming a membrane | film | coat is mentioned. Specifically, in addition to the photosensitive layer coating solution and the thermosensitive layer coating solution, the intermediate layer coating solution for improving the adhesion of the plate making layer by forming an intermediate layer on the surface of the web, and the plate making surface of the lithographic printing plate web Polyvinyl alcohol aqueous solution used to form an anodic oxide film that protects from oxidation, photosensitizer colloid solution for photographic film used to form photosensitive layer in photographic film, and photosensitive layer of photographic paper Examples thereof include a photographic paper colloid solution for photographic paper, a recording tape, a video tape, a magnetic layer forming solution used for forming a magnetic layer of a floppy disk, and various paints used for metal coating.

  Next, a coating apparatus used in the coating system of the present embodiment will be described. FIG. 5 is a schematic configuration diagram of the gravure coating apparatus, and FIG. 6 is a schematic configuration diagram of the bar coating apparatus.

  Hereinafter, a preferred embodiment of the gravure coating apparatus of the present invention will be described in detail.

  The gravure coating apparatus mainly includes a gravure roll in which a lower part of the roll is immersed in a coating liquid storage tank in which a coating liquid is stored, a pass roller that forms a travel path of a support so that the coating liquid is applied by the gravure roll, and a gravure The blade comprises a blade that measures the amount of coating on the support by bringing the tip into contact with the roll surface of the roll and scraping off the coating solution excessively adhered to the roll surface, and a blade holder that holds the blade.

  The gravure roll has an uneven engraving process (for example, a hatched version) that adheres and holds the coating liquid in the coating liquid storage tank on the roll surface, and the gravure roll rotates to apply the coating in the coating liquid storage tank. The liquid is transferred and applied to a continuously running support through a gravure roll. It is preferable to use a gravure roll having a diameter in the range of 30 mm to 300 mm, and a gravure roll having a diameter of 50 mm or less is referred to as a micro gravure roll. Moreover, the width | variety of a gravure roll can use the thing of 200 mm-2000 mm preferably.

  The blade is supported by a blade support device via a blade holder, and the blade width is formed substantially equal to the gravure roll width. The material of the blade is preferably a metal (SK material) from the viewpoint of wear. The blade contact angle θ is generally preferably 30 ° ± 10 °. Here, the contact angle θ is an upward angle of the blade with respect to the horizontal line.

  In the embodiment of the present invention, the example of the kiss reverse method in which the backup roller is not used is described as the gravure coating device, but a gravure coating device having a backup roller as shown in FIG. In the embodiment of the present invention, the reverse method is described in which the rotation direction of the gravure roll and the traveling direction of the support are opposite to each other, but the present invention is also applied to the case where the rotation direction of the gravure roll and the traveling direction of the support are the same. Can be applied.

  As shown in FIG. 5, the gravure coating apparatus 100 includes a manifold block 113 in which a concave portion 111 having a substantially arc-shaped cross section is formed, and a gravure roll 115 disposed in the concave portion 111 so as to be continuously rotatable. Have. A gap is formed between the recess 111 and the gravure roll 115, and the gap constitutes the liquid retention part 119. A liquid supply path 117 is formed so as to communicate with the liquid distillation part 119. The coating liquid 14 is excessively and continuously supplied from the outside through the liquid supply path 117 to the liquid distillation section 119 by a pump (not shown). When the liquid retention part 119 is filled with the coating solution 14, the lower outer peripheral surface of the gravure roll 115 is immersed in the coating solution 14.

The gravure roll 115 rotates in the direction of arrow A at a constant peripheral speed. The web 12 runs continuously in the direction of arrow B. The upper outer peripheral surface of the gravure roll 115 and the lower surface of the web 12 come into contact with each other, and the coating liquid 14 is transferred from the upper outer peripheral surface of the gravure roll 115 to the lower surface of the web 12.

  A dam block 125 is attached to the manifold block 113 on the upstream side of the liquid retaining portion 119, and a dam block 127 is attached on the downstream side. The dam block 125 and the dam block 127 raise the liquid level in the liquid retaining portion 119 above the axis of the gravure roll 115. A doctor blade 223 that can contact the tip is provided on the downstream side in the longitudinal direction of the upper outer peripheral surface of the gravure roll 115. Excess coating liquid is scraped off from the gravure roll 115 by the doctor blade 223.

  Since the excessively supplied coating solution 14 is transferred to the web 12 by the gravure roll 115, the thickness of the thick coating portion tends to be nonuniform at the end portion of the web. In particular, when using the gravure roll 115 in which the spiral groove is formed in order to spread the coating liquid in the width direction of the web, the coating liquid filling the spiral groove moves to the end of the web as the gravure roll 115 rotates. Whether the spiral groove comes to the end portion of the web or the smooth portion between the spiral grooves comes to the end portion of the web, the thickness of the thick coating portion becomes non-uniform (periodic). When such a coating apparatus is used, the combination of the leveling member and the suction nozzle is effective because the thick coating portions generated at both ends of the web can be reliably removed.

  Hereinafter, a preferred embodiment of the bar coating apparatus will be described in detail.

  The coating apparatus main body is composed of a coating bar, a coating liquid discharge section mainly composed of a bar support member that supports the coating bar and a barrier plate, and a base. The support is wound around a pass roller.

  The coating bar is formed in a columnar shape and is rotatably supported by a bar support member. And it rotates around an axis line, contacting the lower surface of the support body in driving | running | working. The direction of rotation of the coating bar is preferably opposite to the running direction of the web, and the peripheral speed of the coating bar is set to be within 1% of the running speed of the support. Note that the rotation direction of the coating bar may be the same as the traveling direction. The support is brought into contact with the coating bar in a state where tension is applied, and is brought into contact with a predetermined wrap angle. The bar support member is formed by combining a plurality of blocks, and an arc-shaped groove is formed on the upper surface. A coating bar is engaged with the groove and is supported rotatably.

  A bar coating apparatus 200 shown in FIG. 6 has a coating head 216 having a bar 214. The coating head 216 includes a substantially cylindrical bar 214 and a support member 218 that supports the bar 214. An arc-shaped recess is formed on the support member 218, and the bar 214 is supported by the recess. .

  A weir 220 is provided upstream of the support member 218 in the traveling direction of the web 12, and a weir 222 is provided downstream. A slit 224 is formed between the support member 218 and the weir 220, and a slit 226 is provided between the support member 218 and the weir 222. Tanks (not shown) are connected to the slits 224 and 226, and the coating liquid is excessively fed from the tanks to the slits 224 and 226 by a pump. The coating liquid 14 forms a liquid pool (bead) on the upstream side (primary side) and the downstream side (secondary side) of the bar 214, and is measured by the bar 214 to apply the coating liquid to the web 12.

  The spiral groove 232 is formed with a certain interval, and the outer peripheral surface is left as it is as the smooth portion 234 between the spiral grooves 232 and 232.

A liquid reservoir 228 is provided on the upstream side of the weir 220, and a liquid reservoir 230 is provided on the downstream side of the weir 220. Excess coating liquid is collected in these liquid reservoirs 228 and 230.
FIG. 7 is a front view showing the bar 214. As shown in FIG. 7, a plurality of spiral grooves 232 are formed on the outer peripheral surface of the bar 214. The spiral groove 232 is continuously formed in a spiral shape, and is further inclined at an angle β with respect to a plane orthogonal to the central axis L of the bar 214. The angle β is preferably 15 degrees or more and 60 degrees or less, and more preferably 20 degrees or more and 50 degrees or less. This is because the occurrence of streaks in the coating process can be suppressed by setting the angle β to the above-described range. The bar coating apparatus having the above-described configuration feeds an excessive coating liquid by a pump and applies it later. Since it is a coating method that measures the amount, thick coated portions with non-uniform thickness are likely to occur at both ends in the width direction of the web.

  When such a coating apparatus is used, the combination of the leveling member and the suction nozzle is effective because the thick coating portions generated at both ends of the web can be reliably removed.

[Example]
Hereinafter, the present invention will be described more specifically with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

The following infrared-sensitive lithographic printing plate precursor coating solution was coated on a support with a bar coater.
(Coating solution)
N- (4-aminosulfonylphenyl) methacrylamide / acrylonitrile / methyl methacrylate copolymer (36/34/30% by mass: weight average molecular weight 50000)
1.9g
M / p cresol novolak (m / p = 6/4, weight average molecular weight 4500)
0.3g
・ Infrared absorbing cyanine dye 0.13g
・ Ethyl violet 0.078g
-Fluorosurfactant (Megafac F780, manufactured by Dainippon Ink & Chemicals, Inc. 30% methyl ethyl ketone) 0.2g
・ Methyl ethyl ketone 16.0g
1-methoxy-2-propanol 8.0g
・ Γ-Butyrolactone 8.0g
Table 1 summarizes the viscosity of the coating liquid, the coating amount, the conditions of the leveling member, and the evaluation.

  Regarding the evaluation, (1) streaks of the edge portion cannot be confirmed visually, (2) the sensitivity difference of the edge portion is ± 5% or less with respect to the center portion with the Gretag color densitometer, and (3) the lower layer is exposed. ○ if all the conditions for not doing so are satisfied. Other than that, it is X.

吸引条件としては、吸引ノズル１２の吸引圧力が１０〜７０ｋＰａの範囲、洗浄液の流量が１００〜５００ｃｃ／分の範囲が好ましい。

As the suction conditions, the suction pressure of the suction nozzle 12 is preferably in the range of 10 to 70 kPa, and the flow rate of the cleaning liquid is preferably in the range of 100 to 500 cc / min.

  The distance between the suction port of the suction nozzle and the thick coating portion is preferably in the range of 0.2 to 2 mm. The horizontal position of the suction port in the horizontal direction is the distance in the horizontal direction from the end of the web to the center of the suction port, the distance from the outside of the web to the outside is 2 mm, and the distance from the end of the web to the inside is 5 mm. It is preferable to be within the range.

  From the result of Table 1, according to this coating system, the thick coating part of a web edge part can be removed reliably.

  DESCRIPTION OF SYMBOLS 10 ... Coating system, 12 ... Web, 14 ... Coating liquid, 16 ... Coating device, 18 ... Leveling member, 20 ... Suction nozzle, 40 ... Coating film, 40A ... Thick coating part

Claims (8)

A coating system for forming a coating film by supplying a coating solution to a continuously running support,
A coating type coating device for feeding excess coating liquid and then measuring the coating amount;
A leveling member that is disposed downstream of the coating device and that makes the thick coating portion of the coating film at the end in the width direction of the support have a constant thickness;
A suction device that is disposed downstream of the leveling member and removes a part of the coating film at the widthwise end of the support;
A coating system.   The coating system according to claim 1, wherein the leveling member is a flat plate made of a polymer material having a thickness of 0.3 mm or less.   The coating system according to claim 1, wherein the leveling member is a brush having a wire diameter of 0.3 mm or less.   The coating system according to any one of claims 1 to 3, wherein the leveling member is inclined at a predetermined angle or more with respect to a direction orthogonal to the traveling direction of the support, and the surface of the leveling member is inward with respect to the traveling direction of the support. An application system that is arranged to face the surface.   5. The coating system according to claim 4, wherein the leveling member is tilted by 5 degrees or more with respect to a direction orthogonal to the traveling direction of the support.   The coating system according to claim 1, wherein the coating apparatus is at least one of a gravure coating apparatus and a bar coating apparatus.   It is a coating system of Claim 6, Comprising: The gravure roll of the said gravure coating apparatus, or the bar of the said bar coating apparatus is 15 degrees or more and 60 degrees or less with respect to the direction orthogonal to the center axis | shaft of the said gravure roll or the said bar. Application system with inclined spiral grooves. Application method,
A step of supplying a coating solution to a continuously running support by a post-measuring coating type coating apparatus and forming a coating film;
A leveling member disposed downstream of the coating apparatus, and a step of leveling the coating portion of the coating film at the end in the width direction of the support to a constant thickness;
Removing a part of the coating film at the widthwise end of the support by a suction device disposed downstream of the leveling member;
A coating method comprising:

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