JP2011206698A - Gravure coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gravure coating apparatus which can efficiently perform coating having desired gradation even when using a coating liquid containing a relatively large granular material (for example, a powder having a particle size of 20-200 μm).SOLUTION: The gravure coating apparatus 1A includes a liquid tank 2 for accommodating the coating liquid W, a gravure roller 3 disposed so as to be immersed in the coating liquid W in the liquid tank 2 and having a large number of cells storable of the coating liquid W on the outer peripheral surface 3a, and a backup roller 4 disposed above the gravure roller 3. A sheet 10 to be coated is nipped between both rollers 3, 4 and the coating liquid W in the cells is applied to the sheet 10 to be coated. The outer peripheral surface 4a of the backup roller 4 is provided with recesses and projections.

Description

  The present invention relates to a gravure coating apparatus. Specifically, the present invention relates to a gravure coating apparatus suitable for coating a coating liquid containing a powder having a large particle diameter of 20 to 200 μm.

  Conventionally, a gravure roll (gravure plate cylinder) in which a large number of cells capable of storing the coating liquid are formed on the outer peripheral surface as a coating device for applying the coating liquid to a coated sheet such as paper or film. And a gravure coating apparatus provided with a backup roll (impression cylinder) that presses the coated sheet between the gravure roll and the gravure roll is known. FIG. 7 shows an outline of a conventional gravure coating apparatus. A gravure coating apparatus 91 shown in FIG. 7 includes a gravure roll 92 and a backup roll 93 disposed to face the gravure roll 92. Below the gravure roll 92, a liquid tank 94 for storing the coating liquid W is provided. Further, a doctor blade 95 that scrapes off the coating liquid W on the outer peripheral surface of the gravure roll 92 is provided. In the gravure coating apparatus 91 having such a configuration, the coating liquid W in the liquid tank 94 is rotated by rotating both the rolls 92 and 93 or only the roll 92 in the direction indicated by the arrow in the drawing by a roll driving device (not shown). Is supplied into a large number of cells formed on the outer peripheral surface of the gravure roll 92, the excess coating liquid W on the outer peripheral surface is scraped off by the doctor blade 95, and the coating liquid W in the cell is It is applied to the coated sheet 90 pressed between both rolls 92 and 93.

  Japanese Patent Application Laid-Open No. H10-228561 describes a technique for developing a streak pattern on a surface to be coated using a gravure coating apparatus. In the technique described in Patent Document 1, after applying a cationic coating liquid as a lower layer to a base material and drying it, an anionic coating liquid is applied on the lower layer by a gravure coating apparatus. A streak pattern with a high design property is expressed by rapidly gelling at the boundary surface between the upper and lower layers. Patent Document 2 describes that, in gravure printing using phosphorescent ink or fluorescent ink, the phosphorescent effect or the fluorescence effect can be ensured by setting the cell depth of the gravure roll to a specific range.

Japanese Patent No. 2812284 Japanese Patent No. 3464476

  Gravure coating is achieved with a single coating head (with a single coating operation) by adjusting the cell size (opening degree, depth, etc.) of the gravure roll. With such coating, it is possible to express the light and shade due to the difference in the amount of the coating liquid component adhering to the coated surface of the coated sheet. However, for example, when applying a coating solution containing a granular material having a relatively large particle diameter of about 20 to 200 μm, represented by a high brightness pigment such as an aluminum paste or a pearl pigment, the following reasons This limits the expression of gradation. In other words, a certain degree of cell opening degree is always required to allow a granular material having a large particle size to enter the gravure roll cell and then transfer to the coated sheet without being scraped off by the doctor blade. Thus, the coating amount distribution cannot be set below the opening degree. There has not yet been provided a gravure coating apparatus that can utilize existing facilities to the maximum and efficiently realize coating with a desired gradation.

  Accordingly, an object of the present invention is to efficiently realize coating with a desired gradation even when a coating liquid containing a relatively large granular material (for example, a powder having a particle diameter of 20 to 200 μm) is used. The object is to provide a gravure coating apparatus.

  The present invention comprises a gravure roll having a large number of cells capable of storing a coating liquid on its outer peripheral surface, and a backup roll arranged above the gravure roll, and is arranged between the two rolls or between the two rolls. In the gravure coating apparatus that nips the coated sheet between the offset roll and the backup roll, and coats the coated liquid on the coated sheet, the outer peripheral surface of the backup roll has irregularities. By providing the attached gravure coating apparatus, the above-mentioned problems are solved.

  Further, the present invention is a backup roll used for gravure coating using a gravure roll having a large number of cells capable of storing a coating liquid on the outer peripheral surface, and the outer peripheral surface of the backup roll is uneven. The problem is solved by providing a backup roll.

  According to the present invention, even when a coating liquid containing a relatively large granular material (for example, a powder having a particle diameter of 20 to 200 μm) is used, the coating with gradation is not affected by the above-described limitation. The work can be efficiently realized at a relatively low cost.

FIG. 1 is a schematic view showing an embodiment of a gravure coating apparatus of the present invention. FIG. 2 is a perspective view of a gravure roll in the gravure coating apparatus shown in FIG. 3A is an enlarged plan view showing a part of the outer peripheral surface of the gravure roll shown in FIG. 2, and FIG. 3B schematically shows a cross section taken along the line II of FIG. 3A. It is sectional drawing. 4 is a perspective view of a sheet-like material constituting the backup roll shown in FIG. FIG. 5 is a plan view schematically showing a coating pattern obtained by the gravure coating apparatus shown in FIG. FIG. 6 is a schematic view showing another embodiment of the gravure coating apparatus of the present invention. FIG. 7 is a schematic view showing an example of a conventional gravure coating apparatus.

  Hereinafter, the present invention will be described based on a preferred embodiment thereof with reference to the drawings. As shown in FIG. 1, the gravure coating apparatus 1 </ b> A of the first embodiment is disposed so as to be immersed in the liquid tank 2 in which the coating liquid W is stored and the coating liquid W in the liquid tank 2. A gravure roll 3 and a backup roll 4 disposed above the gravure roll 3, the coated sheet 10 is nipped between the rolls 3 and 4, and the coating liquid W is applied to the coated sheet 10. It is something to work on.

  A coating liquid supply means (not shown) for supplying the coating liquid W to the liquid tank 2 is connected to the liquid tank 2. The coating liquid supply means includes a tank that stores the coating liquid W, a pump that supplies a certain amount of the coating liquid from the tank to the liquid tank 2, a pipe that connects these, and the like.

  The gravure roll 3 and the backup roll 4 are both cylindrical rolls supported so as to be rotatable around the roll axis, and are arranged side by side with the respective roll peripheral surfaces 3a and 4a facing each other. The roll shafts of both the rolls 3 and 4 or the gravure roll 3 are provided with drive means (not shown), and the rolls 3 and 4 are synchronized by transmitting the drive force from the drive means. And is designed to rotate. Both rolls 3 and 4 are each configured to include a metal rigid body such as an aluminum alloy or steel.

  As shown in FIGS. 2 and 3, the gravure roll 3 has a large number of cells 30 that can store the coating liquid W on the outer peripheral surface 3 a thereof. More specifically, the outer peripheral surface 3 a of the gravure roll 3 is provided with a plurality of linear image line portions 31 and 32 that intersect both the circumferential direction X and the roll axis direction Y of the gravure roll 3. A cell 30 is formed in a region defined by the image line portion 31 and the image line portion 32 that intersect each other. The cell 30 is a concave portion that is recessed from the image line portions 31 and 32, and the outer peripheral surface 3 a of the gravure roll 3 is uneven by the cell 30 as the concave portion and the image line portions 31 and 32 as the convex portions. ing. Each cell 30 has an inverted pyramid-shaped quadrangular pyramid shape, and its opening has a quadrangular shape in plan view as shown in FIG. Here, the shape of each cell 30 may be a quadrangular pyramid or the like in addition to the inverted pyramid type, and is not particularly limited. Many cells 30 have the same shape and the same size. The gravure roll 3 itself can be configured similarly to the gravure roll in this type of gravure coating apparatus.

  As shown in FIG. 1, the outer peripheral surface 3 a of the gravure roll 3 is on the upper side of the gravure roll 3 and upstream of the nip portion with the backup roll 4 (contact portion with the coated sheet 10). A doctor blade 5 is provided to scrape off the excess of the coating liquid W supplied above.

  Further, as shown in FIG. 1, guide rolls 6 and 7 are arranged above the gravure roll 3 and in the front-rear direction of the backup roll 4. The long strip-shaped coated sheet 10 is passed through a guide roll 6 and a nip portion N formed by the gravure roll 3 and the backup roll 4 by a sheet conveying means (not shown), and then the guide roll 7. It is conveyed through. The guide rolls 6 and 7 are arranged so as to be movable up and down. By adjusting the arrangement position of the guide rolls 6 and 7, the tension at the time of conveying the coated sheet 10 can be adjusted.

  One of the main features of the gravure coating apparatus 1 </ b> A of the first embodiment is the backup roll 4. The normal outer surface of this type of backup roll has no irregularities and is flat (smooth), while the outer peripheral surface 4a of the backup roll 4 according to the first embodiment has irregularities. More specifically, as shown in FIG. 1, the backup roll 4 according to the first embodiment is a sheet having an uneven surface on the outer peripheral surface of a cylindrical roll core body 40 made of a metal rigid body. An object 41 is wound around and configured. The entire outer peripheral surface of the roll core 40 is covered with a sheet-like object 41. The roll core body 40 and the sheet-like object 41 are joined by a known joining means such as an adhesive.

  As shown in FIG. 4, the sheet-like object 41 is provided with a plurality of convex portions 42 and concave portions 43 on the one surface 41a side, and the one surface 41a is an uneven surface. On the other hand, the other surface 41b of the sheet-like object 41 is a flat surface having no irregularities. One surface (uneven surface) 41 a of the sheet-like material 41 forms the outer peripheral surface 4 a of the backup roll 4, and the flat other surface 41 b is a surface facing the backup roll 4 (joint surface). The convex portion 42 has a rectangular shape extending in the circumferential direction X of the backup roll 4 in plan view, and has a rectangular parallelepiped shape in sectional view along the roll axis direction Y (CD) orthogonal to the circumferential direction X. The inside of the convex portion 42 is filled with a material for forming the sheet-like material 41 (fiber, resin, etc.). The plurality of convex portions 42 are all formed to have the same shape and the same size, and are arranged at a predetermined interval on the CD, and a concave portion 43 is formed between the two convex portions 42 and 42 adjacent to each other. Yes. The upper surface portion 42a of the convex portion 42 and the bottom surface portion 43a of the concave portion 43 are flat. Thus, on one surface 41a of the sheet-like material 41 forming the outer peripheral surface 4a of the backup roll 4, the convex portions 42 and the concave portions 43 are alternately arranged on the CD, whereby the one surface 41a is uneven. ing.

  The sheet-like object 41 is formed by embossing a flat sheet-like base material. Examples of the sheet-like base material constituting the sheet-like material 41 include paper; woven fabric; non-woven fabric; resin film such as polyolefin, polyester, polyethylene terephthalate, polyamide, polyvinyl chloride, polycarbonate, fluororesin; chloroprene rubber, nitrile Rubber materials such as rubber, butyl rubber, urethane rubber and silicon rubber, and metal foil such as aluminum foil, iron foil, and copper foil can be used. The sheet-like material 41 needs durability for practical use, and when the hardness of the sheet-like material 41 is too high, the cell 30 may be damaged due to contact between the concavo-convex portion and the gravure roll 3. Therefore, the sheet-like substrate 41 is preferably a resin film or a rubber material.

  As the coated sheet 10, paper, a resin film, a metal foil, a composite thereof, or the like is usually used. As the coating liquid W, ink, adhesive liquid, overcoat liquid, anchor coat liquid or the like is usually used. The ink is usually configured to include a color material (dye, pigment, etc.) and a liquid medium such as water or an organic solvent.

  In the gravure coating apparatus 1A having such a configuration, as shown in FIG. 1, a long strip-shaped coated sheet 10 includes a nip portion N formed by a guide roll 6, a gravure roll 3, and a backup roll 4, And it passes along the guide roll 7 sequentially and is conveyed in the direction (MD) shown by X1 in FIG. During this time, the gravure roll 3 arranged so that the lower part is immersed in the coating liquid W in the liquid tank 2 rotates in the direction indicated by the arrow in the figure, so that the coating liquid W is placed on the outer peripheral surface 3a. It is supplied and stored in the cell 30 formed on the outer peripheral surface 3a. The coating liquid W supplied onto the outer peripheral surface 3 a is transferred to the nip portion N after the surplus portion is scraped off by the doctor blade 5.

  In the nip portion N, the coated sheet 10 is pressed between the gravure roll 3 and the backup roll 4 with a predetermined nip pressure, whereby coating on the outer peripheral surface 3a of the gravure roll 3 (in the cell 30) is performed. The liquid W is transferred to the surface (coating surface) facing the gravure roll 3 of the coating sheet 10. At this time, the outer peripheral surface 4a of the backup roll 4 that is in contact with the coated sheet 10 is not flat (smooth) as described above, and has irregularities as shown in FIG. A pressure difference due to the unevenness occurs in the coated sheet 10, and thereby the coating amount of the coating liquid W (transfer amount from the gravure roll 3 to the coated sheet 10) becomes non-uniform. Specifically, in the coated sheet 10 in the nip portion N, the portion corresponding to the convex portion 42 of the backup roll 4 (sheet-like material 41) is pressed more strongly than the portion corresponding to the concave portion 43, and thus the coating sheet 10 is coated. The coating amount of the working liquid W is relatively increased. On the other hand, the portion corresponding to the concave portion 43 is pressed weaker than the portion corresponding to the convex portion 42, so that the coating amount of the coating liquid W is relatively small, and the depth of the concave portion 43 (the height of the convex portion 42 is high). In some cases, the pressure is hardly pressed and the coating liquid W is not substantially applied. In this way, the shade due to the difference in the coating amount of the coating liquid W is expressed on the surface to be coated of the sheet 10 to be coated, and coating with gradation is obtained.

  FIG. 5 shows a coating pattern of the coated sheet 10 that has passed through the nip portion N as an example of the coating pattern according to the present invention. As shown in FIG. 5, the coating surface of the coating sheet 10 is substantially coated with the multi-coating portion 12 having a relatively large coating amount of the coating liquid W and the coating liquid W. Or a non-or small coating portion 13 in which the coating amount of the coating liquid W is relatively small is formed. The multi-coating portion 12 is a portion pressed by the convex portion 42 of the backup roll 4 (sheet-like material 41) in the nip portion N, and is formed in the same number as the convex portion 42 in the backup roll 4. Further, the non- or small coating portions 13 are portions pressed by the concave portions 43 of the backup roll 4 (sheet-like material 41) in the nip portion N, and the same number as the concave portions 43 in the backup roll 4 is formed. The multi-coating portion 12 and the non-or small coating portion 13 each have a rectangular shape extending in the transport direction X1 (MD) in plan view, and are alternately arranged in a direction Y (CD) orthogonal to the transport direction X1. Has been.

  The coated sheet 10 thus coated with gradation on the coated surface is then naturally dried or heated forcibly dried, whereby a coating film is formed on the intended coated sheet 10. Thus, a coated sheet on which is formed is obtained. When the coated sheet 10 is forcibly dried by heating, examples of the heating means include an electric drying furnace (natural convection type or forced convection type), a hot air circulation type drying furnace, drying using both far infrared heating and hot air circulation. A well-known thing, such as a furnace, can be used without particular limitation.

  From the viewpoint of more reliably obtaining a coating with a desired gradation, the height T1 of the convex portion 42 of the sheet-like material 41 (see FIG. 4, height from the bottom surface portion 43a of the concave portion 43). Is preferably 5 μm or more, more preferably 50 μm or more. When the height T1 is less than 5 μm, even if the sheet-like material 41 of any hardness is used, a pressure difference that affects the coating amount difference when niped with the gravure roll 3 cannot be obtained, This is not preferable because there is a possibility that a coating with gradation is not obtained.

  According to the gravure coating apparatus 1A of the first embodiment, since the outer circumferential surface 4a of the backup roll 4 is uneven, a pressure difference is generated in the coated sheet 10 at the nip portion N with the gravure roll 3, Thereby, the coating pattern with the gradation property resulting from the coating amount difference of the coating liquid W can be applied to the coated sheet 10 with one coating head (in one coating operation). it can. The coating pattern with gradation can be changed by appropriately adjusting the shape, size, and arrangement of the convex portions 42 and the concave portions 43 constituting the irregularities.

  Moreover, when applying the coating liquid containing the granule of a comparatively large particle diameter about 20-200 micrometers in gravure coating, let this granule enter the cell of a gravure roll, and then In order to transfer to the coated sheet so that it is not scraped off by the doctor blade, a certain degree of cell opening is always required. Conventionally, the coating amount distribution can be set below the opening degree. There is a problem that the range of gradation that can not be expressed is limited. On the other hand, since the gravure coating is performed using the backup roll 4 according to the first embodiment, it is not necessary to particularly modify the gravure roll (cell) for the purpose of obtaining a coating with gradation. Even when a coating liquid containing a relatively large granular material is used, it is possible to perform coating with a wide gradation range without being restricted by the cell size. In addition, the backup roll 4 is configured by winding a sheet-like object 41 having irregularities on the outer peripheral surface of a normal cylindrical metal roll core body 40, and existing equipment (normal Therefore, according to the first embodiment, coating with gradation can be realized efficiently at a relatively low cost.

  FIG. 6 shows a second embodiment of the gravure coating apparatus of the present invention. In addition, about 2nd Embodiment, the different structure part from 1st Embodiment mentioned above is mainly demonstrated, the same code | symbol is attached | subjected to the same structure part, and description is abbreviate | omitted. The description of the first embodiment is appropriately applied to components that are not particularly described.

  The gravure coating apparatus 1B of the second embodiment is a so-called offset gravure coater, and includes an offset roll 8 disposed between the gravure roll 3 and the backup roll 4, as shown in FIG. The coated sheet 10 is nipped with the backup roll 4, and the coating liquid W is applied to the coated sheet 10. The offset roll 8 is a cylindrical roll supported so as to be rotatable around the roll axis, and the outer peripheral surface 8a is formed of rubber or the like, and is a flat (smooth) surface without irregularities. In the gravure roll 3, or the gravure roll 3 and the offset roll 8, or the gravure roll 3, the offset roll 8, and the backup roll 4, both the gravure roll 3 and / or the gravure roll 3 and the backup roll 4 are used. A driving means (not shown) is provided, and the offset roll 8 rotates in synchronization with the gravure roll 3 and the backup roll 4 by transmitting a driving force from the driving means. As the offset roll 8, an offset roll in a normal offset gravure coater can be used.

  In the gravure coating apparatus 1B, the coating liquid W supplied onto the outer peripheral surface 3a by the rotation of the gravure roll 3 is applied to the offset roll 8 at the nip portion N1 formed by the gravure roll 3 and the offset roll 8. Transferred onto the outer peripheral surface 8a. At this time, the transfer pattern of the coating liquid W formed on the outer peripheral surface 8a is a pattern corresponding to the arrangement pattern of the cells 30 on the outer peripheral surface 3a. Thus, the coating liquid W transferred to the offset roll 8 in a predetermined pattern is transferred to the nip portion N2 formed by the offset roll 8 and the backup roll 4, and is applied to the coated sheet 10 at the nip portion N2. Coated. The coating of the coating liquid W onto the coated sheet 10 at the nip portion N2 is the same as the coating at the nip portion N in the first embodiment described above. Also with the gravure coating apparatus 1B of the second embodiment, coating with gradation can be efficiently obtained as in the gravure coating apparatus 1A of the first embodiment.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the embodiment, as the backup roll, the backup roll 4 configured by winding the sheet-like object 41 having irregularities on the surface on the outer peripheral surface of the cylindrical roll core body 40 is used. Is sufficient if the outer peripheral surface of the backup roll is provided with unevenness, and without using the sheet-like material 41, the outer peripheral surface of the metal roll core 40 may be directly engraved or the like. good. However, the use of the backup roll 4 including the sheet-like material 41 is preferable from the viewpoints of utilizing existing facilities and reducing costs.

  Moreover, in the said embodiment, although the gravure roll 3 was arrange | positioned so that it might be immersed in the coating liquid W in the liquid tank 2, it replaced with such a structure and the gravure roll 3 and the liquid tank 2 An inking roll (not shown) is rotatably provided around the roll axis, and the lower part of the inking roll is immersed in the coating liquid W in the liquid tank 2 through the inking roll. The coating liquid W in the liquid tank 2 may be supplied onto the outer peripheral surface 3 a of the gravure roll 3.

Further, in the sheet-like object 41, the convex portion 42 is filled with the material for forming the sheet-like object 41 (fiber, resin, etc.), but may be hollow.
Moreover, the uneven | corrugated pattern in the backup roll 4 (sheet-like object 41) is not restrict | limited to stripe shape as shown in FIG. 4, It can set suitably. In the above-described embodiment, the plurality of convex portions 42 have the same shape and the same size, but the shape and / or size may not be uniform. In other words, the backup roll 4 (sheet-like object 41) may have a plurality of types of convex portions 42 having different shapes and / or dimensions. For example, the height T1 so that the height T1 (see FIG. 4) of the convex portion 42 gradually decreases or increases in one direction (right direction or left direction in FIG. 4) in the roll axis direction Y (CD). By providing a plurality of different types of convex portions 42, it is possible to obtain a coating pattern with gradation that the coating amount of the coating liquid W gradually decreases or increases in the one direction. become.

1A, 1B, 91 Gravure coating device 2, 94 Liquid tank 3, 92 Gravure roll 3a Gravure roll outer peripheral surface 30 Cell 4, 93 Backup roll 4a Backup roll outer peripheral surface 40 Roll core 41 Sheet-like object 42 Projection 43 Concave part 5,95 Doctor blade 6,7 Guide roll 8 Offset roll 10,90 Sheet to be coated 12 Multi-coating part 13 Non-or small coating part W Coating liquid

Claims (3)

An offset roll provided with a gravure roll having a large number of cells capable of storing a coating liquid on its outer peripheral surface, and a backup roll arranged above the gravure roll, and arranged between the two rolls or between the two rolls In the gravure coating apparatus that nips the coated sheet between the backup roll and the coating liquid, the coating liquid is coated on the coated sheet.
A gravure coating apparatus in which irregularities are provided on the outer peripheral surface of the backup roll.   The gravure coating apparatus according to claim 1, wherein the backup roll is configured by winding a sheet-like object having irregularities on a surface thereof on an outer peripheral surface of a cylindrical roll core.   A backup roll used for gravure coating using a gravure roll having a large number of cells capable of storing a coating solution on the outer peripheral surface thereof, wherein the outer peripheral surface of the backup roll has irregularities.

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