JP2015202673A - Crown-shaped plate cylinder and flexographic printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means which can form a printing pattern of a functional thin film with a reduced printing deviation.SOLUTION: A plate cylinder 105 for use in a flexographic printing device for forming a functional thin film on a base material, which comprises a crown-shaped plate cylinder 405 of which a central part has a diameter larger than that of an end part, a degree of increase of the diameter is made to be larger towards the end part, and in contrary to this, a degree of increase of the diameter is made to be smaller towards the central part, characterized in that a crown quantity, which is a difference between the diameters of the central part and the end part of the plate cylinder, is 0.10 mm to 0.25 mm.

Description

  The present invention relates to an apparatus for producing a functional thin film, and more particularly to a flexographic printing apparatus in which a pattern is not distorted even when a flat flexographic plate is wound around a plate cylinder.

  Efforts have been made to develop a new device by forming a fine pattern by a printing method that is excellent in inexpensive manufacturing cost and mass productivity. In particular, in the display field, an attempt to form a fine pattern made of a functional thin film by a printing method has been made as a technique for achieving both production efficiency and large area.

  Currently developed printing methods include inkjet printing, nozzle printing, offset printing, gravure printing, gravure offset printing, flexographic printing, and the like.

  Among the various printing methods, the flexographic printing method, in particular, supplies ink to the surface of the flexographic plate by using a flexographic printing plate that is a resin relief plate and an ink roll called an anilox roll that has regular irregularities formed on the surface. This is a printing method in which a fine pattern is formed by transferring to a film. Flexographic printing is used for printing corrugated cardboard liners, packaging films, and the like, and is particularly suitable for forming a thin and stable printing layer having a thickness of about 0.01 to 0.2 μm.

  Flexo printing allows printing at a very low printing pressure, which is called kiss touch with almost no printing pressure, so its characteristics can be achieved by applying an extremely thin glass substrate used for electronic parts such as displays and high printing pressure. It is also suitable for printing on a substrate on which a transparent electrode such as ITO that is easily destroyed is formed.

Next, a conventional general flexographic printing apparatus will be described with reference to FIG.
A flexographic printing apparatus shown in FIG. 1 includes a straight plate cylinder 105 on which a flexographic printing plate 104 for pattern formation is mounted via an under-cushion cushion 103, an anilox roll 101 for supplying ink in contact with the flexographic printing plate 104, The printing apparatus includes an ink chamber 108 for supplying ink to the anilox roll 101, a doctor roll 102 for scraping off excess ink on the anilox roll 101, and a substrate surface plate 106 on which the substrate 107 to be printed is placed. .

  Next, the printing flow will be described with reference to FIGS. First, after the substrate to be printed 107 is placed on the substrate surface plate 106, the substrate surface plate 106 is moved to just below the plate cylinder 105. When the movement of the substrate surface plate 106 is completed, the plate cylinder 105 rotates synchronously with the operation of the substrate surface plate 106, and ink is supplied to the flexographic plate 104 from the anilox roll 101 operating at the same speed as the plate cylinder 105. . After the ink is supplied to the flexographic plate 104, the ink on the flexographic plate 104 is quickly transferred to the printing substrate 107, and the printing operation is completed.

  As described above, due to the property that the ink pattern inked on the flexographic plate 104 is directly transferred to the printing substrate 107, the flexographic printing plate 104 has a factor that determines the positional accuracy of the printed pattern in the flexographic printing method. There are the positional accuracy of the ink pattern formed and the straightness of the moving substrate surface plate 106, the rotational speed of the plate cylinder 105, the accuracy of the moving speed of the substrate surface plate 106, and the like.

As a flexographic plate generally used in the flexographic printing method, a plate in which a photosensitive resin is applied to one side of a plate-like substrate made of metal or resin and subjected to uneven patterning by photolithography is used. In particular, when a metal is used as the plate-like substrate, a plate can be produced with an accuracy of a positional deviation of 3 μm or less with respect to the design value by using a proximity exposure apparatus or a projection step exposure apparatus.

  On the other hand, the flexographic plate produced as described above needs to be wound around the plate cylinder 105 of the flexographic printing machine when used. At the time of winding, the ink pattern formed on the flexographic plate 104 is distorted due to the stress applied to the flexographic plate 104 or the distortion of the plate cylinder 105 to be wound, and the pattern transferred to the printing substrate 107 is the plate. It becomes a distorted pattern different from the pattern formed on the flat plate-shaped flexographic plate before being attached to the cylinder 105.

If the size of the flexographic plate exceeds 1 m in the long side direction and 0.5 m in the width direction, it is necessary to pull the flexographic plate with a force of 0.3 N or more when winding the flexographic plate. However, this causes distortion in a fine pattern with L / S = 100 μm or less.
Further, by winding, the pattern expands and contracts more than when placed on a flat surface, which causes an error factor in the printing position in the flow direction (the moving direction of the substrate to be printed 107).

  FIG. 3 shows, as an example, a case where a flexographic plate is wound around a straight plate cylinder 305 having a conventional structure which is not a crown shape. Here, the crown shape refers to a shape whose diameter increases from both ends of the plate cylinder toward the center. The normal plate cylinder is straight (cylindrical).

  In addition, as the size of the substrate 107 to be printed increases, the size of the flexographic plate 104 increases and it is necessary to apply a strong tension. When tension is applied to the flexographic plate 104, distortion is further increased.

  Further, the substrate surface plate 106 on which the substrate 107 to be printed is mounted is driven by a linear servo motor or the like and moves linearly. The straightness of the linear movement is ± 3 μm / m or less.

As described above, there are two types of positional deviation of the print pattern generated in the flexographic printing method, namely, deviation in the flow direction and deviation in the direction orthogonal to the flow direction in the plane of the printing substrate 107.
Here, the printing position deviation in the flow direction can be relatively controlled by adjusting the rotational speed of the plate cylinder 105 and the moving speed of the substrate surface plate 106 and relatively changing the length of the printed pattern to be transferred. It can be easily corrected.

  On the other hand, the displacement of the printing position in the direction orthogonal to the flow direction in the plane of the substrate 107 to be printed is the distortion that occurs when the flexographic plate 104 is wound around the plate cylinder 105 and the substrate surface plate 106 that moves the substrate 107 to be printed. Since the straightness accuracy is observed as overlapping distortion, even if the improvement of the distortion generated in the flexographic plate 104 and the improvement of the distortion caused by the printing operation are performed individually, sufficient effects cannot be obtained, so far The accuracy problem could not be solved.

  For such a problem, for example, Patent Document 1 proposes correcting distortion by applying stress to the flexographic plate or the substrate to be printed with respect to the distortion of the flexographic plate and the printing apparatus measured in advance. Yes. However, when partial tension is applied to the flexographic plate and the substrate to be printed, complicated distortion occurs, and as a result, more complicated distortion than the original distortion occurs in the printed material. It is difficult to use as a technology.

Japanese Patent No. 5434434

  In order to solve such a problem, an object of the present invention is to provide means capable of forming a printing pattern of a functional thin film with little printing deviation.

  As means for solving the above-mentioned problems, the invention according to claim 1 is characterized in that a plate cylinder used in a flexographic printing apparatus for forming a functional thin film on a substrate has a central portion from an end portion of the plate cylinder. A crown-shaped plate cylinder having a larger diameter and a greater degree of increase in the diameter of the portion closer to the end portion, and conversely, a portion of the portion closer to the center portion of the plate cylinder and having a smaller increase in diameter. The crown-shaped plate cylinder is characterized in that a crown amount, which is a difference in diameter between the central part and the end part of the cylinder, is 0.10 mm to 0.25 mm.

  The invention according to claim 2 is a flexographic printing apparatus using the crown-shaped plate cylinder according to claim 1.

  By applying the flexographic printing apparatus of the present invention, it is possible to easily form a printing pattern of a functional thin film without causing a printing position shift when a flexographic plate is used.

FIG. 6 is a schematic cross-sectional view showing an example of the configuration of a conventional flexographic printing apparatus. FIG. 6 is a schematic top view illustrating an example of a configuration of a conventional flexographic printing apparatus. It is an example which shows the condition at the time of winding a flexo plate around the plate cylinder without the crown shape of the conventional structure, and the schematic explanatory drawing explaining the distortion which generate | occur | produces in a flexo plate when a flexo plate is pressed on a plate cylinder. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of the condition at the time of winding a flexographic printing plate around the crown-shaped printing cylinder of this invention around a flexographic printing machine, (top view) is a schematic top view, (cross-sectional view) shows an example of the cross section. A schematic sectional view is shown respectively.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to this drawing.

The flexographic printing apparatus of the present invention is for forming a pattern of a functional thin film on a substrate, and the distortion generated in the flexographic plate when a plate-shaped flexographic plate is wound around a normal straight plate cylinder. It is characterized by having a crown-shaped plate cylinder capable of suppressing the above.
As an anilox roll 101 that can be used in the flexographic printing apparatus of the present invention, a ceramic roll obtained by patterning a chromium oxide film formed by plasma spraying chromium oxide on a core roll made of a SUS material by laser engraving Alternatively, it is possible to use any of the chrome rolls in which the core roll is subjected to copper plating, the resin is applied, the laser patterning is performed, the corrosion treatment is performed, and the obtained pattern is subjected to chrome plating.

As the cell shape formed on the aniloc roll 101, any pattern such as a helical pattern, an FM pattern, a honeycomb pattern, a diamond pattern, or an ART ^™ (registered trademark of PRAXAIR, USA) pattern can be used.

  These patterns may be appropriately angled to prevent moire on the printed material. After these patterns are formed, the surface of the anilox roll 101 is desirably polished to prevent scratching the doctor roll 102 side. Specifically, it is desirable to polish so that protrusions of 4 μm or more are eliminated from the pattern bank portion of the anilox roll 101.

  As a mechanism for rotating the anilox roll 101, it is desirable to perform direct drive with a servo motor capable of controlling rotation with high accuracy because uneven rotation speed greatly affects printed matter. Further, as the mechanism, it is desirable to use a backlashless mechanism when a speed reduction mechanism is used to obtain a required torque.

As an anilox roll 101 that can be used, a core roll made of SUS material, etc., nitrile rubber, silicone rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, butyl rubber, acrylonitrile rubber, ethylene propylene rubber, It may be produced by wrapping urethane rubber or the like, or a material in which a PFA heat shrinkable tube is wound on these rubber layers can be used. These materials such as the rubber layer are selected based on the resistance to the solvent used in the ink.
It is desirable that the surface of the anilox roll 101 such as the rubber layer has an arithmetic surface roughness Ra of 0.1 μm or less and a maximum height Ry of 1 μm or less. By satisfying these conditions, a low dust generation and a smooth liquid scraping surface can be obtained.

  For forming the low surface free energy part in the central area of the peripheral surface of the anilox roll 101, fluororesin film spray coating such as PTFE and PFA, spray coating, formation of a fluororesin film such as plasma polymerization, or perfluoroalkyl It can be produced by using a known method for forming a fluorinated monomolecular film such as vapor deposition of a surface modifying agent having a chain.

  As the hardness of the doctor roll 102 that can be used, any of the hardnesses of New JIS K 6253 A50 can be used within a range of 30 ° to 70 °.

  As the mechanism for rotating the anilox roll 101, since uneven rotation speed has a great influence on the printed matter, it is desirable to use a servo motor that can control the rotation with high precision and to perform direct drive, and to synchronize with the rotation of the anilox roll. It is desirable to have a system that can be controlled in a rotatable manner.

  A crown-shaped plate cylinder 305 is supported at the center of the substrate surface plate 106 in a state that it can rotate through a bearing in a shape orthogonal to the guide rails 112A and 112B.

  FIG. 4 is an explanatory diagram for explaining an example of an embodiment of the present invention. By making the plate cylinder a crown-shaped plate cylinder 405, the diameter of the plate cylinder becomes thicker toward the center portion. When the plate cylinder 405 is viewed in a plane perpendicular to the plate cylinder axis, a force 407 that pushes outward from the plate cylinder acts on the flexographic plate 404, and even if it is wound with a tensile force 406 of 0.3 N or less, there is no distortion. It describes that the flexographic plate 404 can be wound.

For example, when the length of the plate cylinder is 6000 mm, the crown amount (amount of thickening the center part from the end of the plate cylinder) is a radial shape within a range of 0.15 to 0.25 mm on one side as the diameter of the plate cylinder. It is preferable to attach. If it is 0.1 mm or less, the winding accuracy is poor, and if it is 0.3 mm or more, the edge is lifted and the printing nip pressure becomes non-uniform. Here, the radial shape indicates that the portion closer to the end of the plate cylinder has a larger degree of increase in diameter toward the center, and conversely, the portion closer to the center of the plate cylinder increases in diameter toward the center. Refers to the shape of the plate cylinder with a reduced degree (see the top view in Fig. 4)
The so-called radial crown or barrel crown. The degree to which the increase in the diameter of the plate cylinder decreases from the end of the plate cylinder toward the center may be appropriately selected depending on the size and rigidity of the flexographic plate to be wound.

Next, the operation when the flexographic plate is mounted on the crown-shaped plate cylinder of the present invention in this conventional flexographic printing apparatus will be described. The operation is the same as that of a conventional flexographic printing apparatus.
First, after the substrate 107 to be printed is placed on the substrate surface plate 106, a printing operation is started by a print start instruction.
During this time, ink is supplied onto the anilox roll 101, the doctoring of the anilox roll 101 is continuously performed, and the smooth doctored surface is always held. Next, after the substrate surface plate 106 moves directly below the crown-shaped plate cylinder 405 (in FIG. 1, the crown-shaped plate cylinder 405 is mounted instead of the plate cylinder 105), ink is transferred from the anilox roll 101 to the flexographic plate 104. Then, the ink is transferred from the flexographic plate 104 to the printing substrate 107 placed on the substrate surface plate 106 synchronized with the rotation of the crown-shaped plate cylinder 405, and printing is completed.
By performing the above operation, a high-quality printed material can be obtained.

  Examples of the present invention will be described. In addition, this invention is not limited to an Example, The improvement, deformation | transformation, etc. in the range which can achieve this invention do not deviate from the meaning of this invention.

  In this example, an example in which a polymer organic light emitting material is printed on glass with an alignment mark is shown.

  As a printing machine, the printing machine shown in FIG. 1 was used, and a crown-shaped printing cylinder 405 was mounted instead of the printing cylinder 105.

  A chrome roll was used as an anilox roll used in this example. The pattern formed on the roll is a diamond pattern in which square cells each having a side of 65 μm are formed at a pitch of 72.5 μm, and these patterns are formed inclined by 60 ° from the horizontal line of the roll.

Next, for the doctor roll used in this example, the central axis is made of SUS, urethane rubber having a hardness of JIS-A 50 ° is wound around the surface, and processed into a columnar shape so as to be within 0.5 mm with respect to the target diameter. . Further, after winding a PFA heat shrinkable tube on the processed urethane rubber roll, polishing of the entire roll peripheral surface was carried out so that Ra was 0.05 μm and Rz was 1 μm.
In addition, the length of the doctor roll was made to be 10 mm longer for the anilox roll so that the ink on the anilox roll could be scraped with the full width.
In this state, the doctor roll was installed in a shape of pushing 50 μm against the anilox roll. The installed anilox roll was rotated while being controlled by a servo motor, and the doctor roll was rotated along with the anilox roll for doctoring.

  Next, the plate material used will be described.

  A black oil-based dye was applied to the surface of a SUS304 plate having a thickness of 0.2 mm as a reflection suppressing layer by a die coating method so as to have a thickness of 1.5 μm. A negative photosensitive resin mainly composed of polyamide was applied on the surface of this laminate so that the total thickness was 0.1 mm, and used as a base of the plate.

  Thereafter, a negative pattern (effective area opening 106 μm × 100 mm, non-opening space 392 μm × 100 μm, total effective line number 400, size W200 mm, L100) is applied to the plate material using a chrome mask having a pattern of 50 μm. Exposure was performed with a proximity gap opened. After the exposure, development was performed while pouring warm water to form a relief plate having a convex portion height of 90 μm, a convex portion line width of 106 μm, and a space of 392 μm. The prepared relief plate was attached to the plate cylinder of a printing machine using a printing cushion tape having a thickness of 0.5 mm.

  Next, the ink will be described.

An organic light-emitting ink was prepared by dissolving a polyphenylene vinylene derivative, which is a high-molecular organic light-emitting material, in anisole so as to have a concentration of 2%.
When the viscosity of the prepared ink was measured, it was 60 mPa · s, and the surface tension was 34 mN / m. Thereafter, the ink was put into the chamber of the printer.

  Printing was performed on 300 mm square and 0.7 mm thick soda glass using the above apparatus, plate, and luminescent material ink. Printing was performed at a cycle time of 60 s, the doctoring speed was 5 mm / s (Ca = 0.01), and the printing speed was 100 mm / s.

The following evaluation was performed about the board | substrate with which the organic light emitting layer obtained in the Example was formed.
(Evaluation item 1) Amount of printing misalignment with respect to the alignment mark (length measuring device confirmation)
(Evaluation item 2) Uneven evaluation of the entire printed pattern (visual confirmation)

  In the examples, evaluation was performed by measuring the amount of print position deviation in the print width direction after printing. In the state without the pressing roll, the print position deviation in the width direction was ± 3 μm or more, but the printed matter with the pressing roll installed was within the target value ± 3 μm and was within the target value range. Also, no specific unevenness was observed.

  The technique for correcting the distortion of the flexographic plate according to the present invention is not limited to a coating apparatus, and can also be applied to a mechanism that rotates by pressing a roll against a roll-shaped or flat object.

101 Anilox roll 102 Doctor roll 103 Underlay cushion 104 Flexo plate 105 Plate cylinder 106 Substrate surface plate 107 Printed substrate 108 Ink chamber 109 Ink supply mechanism 110 Plate cylinder drive servo motor 112 Guide rail 113 Linear servo motor 304 Flexo plate 305 Straight Plate cylinder 306 Resist pattern 404 Flexo plate 405 Crown plate cylinder 406 Tensile force 407 Force that plate cylinder presses outward

Claims (2)

  A plate cylinder used in a flexographic printing apparatus for forming a functional thin film on a substrate has a larger diameter at the center than the end of the plate cylinder, and the degree of increase in the diameter is closer to the end. A crown-shaped printing cylinder that is large and, on the contrary, has a smaller degree of increase in diameter as the portion is closer to the center of the printing cylinder, and the crown amount, which is the difference in diameter between the central part and the end of the printing cylinder, is 0. A crown-shaped plate cylinder having a diameter of 10 mm to 0.25 mm.   A flexographic printing apparatus using the crown-shaped plate cylinder according to claim 1.