JP2014019061A - Flexographic plate and flexographic press having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexographic plate that can significantly improve durability of a sheet laminate, and can be wound around a plate cylinder; and a flexographic press having the same.SOLUTION: A sheet-like flexographic plate 2 that is used by being wound around an outer peripheral surface S of a plate cylinder 3, includes: a sheet laminate 20 in which a sheet-like surface printing layer 18 in which a transfer surface 17 for printing is formed, and a sheet-like inside reinforcement layer 19 are superimposed; and a pair of holding means 21, 21 that respectively hold both end parts 20a, 20b in a circumferential direction of the sheet laminate 20. The sheet laminate 20 is made to be a non-adhesion state in which the surface printing layer 18 and the inside reinforcement layer 19 can perform relative position slide between the pair of holding means 21, 21.

Description

  The present invention relates to a flexographic plate that can be easily wound around a plate cylinder and can improve durability, and a flexographic printing machine using the same.

  Flexographic printing is known as one of letterpress printing. A flexographic printing machine is used for flexographic printing. The flexographic printing machine includes a plate cylinder and a flexographic plate. The plate cylinder is substantially cylindrical. The flexographic plate is a sheet having flexibility, and is wound around the outer peripheral surface of the plate cylinder. A transfer surface for printing is formed on the outer surface of the flexographic plate. The transfer surface is pressed against a substrate such as paper or a liquid crystal layer to perform printing.

  FIG. 6 shows a cross-sectional view along the length direction of the flexographic plate a before being wound around the plate cylinder. This flexographic plate a includes a sheet laminate d composed of a surface printing layer b and a base material c, and a pair of holding means e (for example, Patent Document 1 below).

  The surface print layer b has a transfer surface formed on the outer surface. The transfer surface is made of an elastic material such as rubber or resin, for example.

  The base material c is bonded to the inner surface of the surface printing layer b by thermocompression bonding or the like. The base material c is made of, for example, a resin sheet such as PET (polyethylene terephthalate) or PP (polypropylene).

  A pair of holding means e is being fixed to the both ends of the length direction (circumferential direction when wound around a plate cylinder) of sheet layered product d. Specifically, the sheet laminate d has through holes f formed at both ends thereof. A plurality of through holes f are usually provided in a direction perpendicular to the length direction of the sheet laminate d. The holding means e includes a pin g that is inserted into the through hole f. The holding means e is also used as a metal fitting that attaches the flexographic plate a to a plate cylinder (not shown) and applies tension to the flexographic plate a.

  In flexographic printing, a plate cylinder (not shown) around which a flexographic plate a is wound is rotated. The substrate is sent to and contacted with the transfer surface of the rotating surface print layer b. Thereby, the ink on the transfer surface, the alignment film, and the like are transferred to the substrate.

Japanese Patent No. 4917669

  At the time of flexographic printing, the surface print layer b and the substrate are in contact. At this time, a shearing force acts on the surface printing layer b of the flexographic plate a. A shearing force also acts on the base material c that is bonded integrally with the surface printing layer b. These shearing forces repeatedly deform the through-holes f and both ends of the sheet laminate d and easily cause damage at an early stage.

  In view of such a situation, it is conceivable to increase the rigidity of the sheet laminate d by increasing the thickness of the inner reinforcing layer c. However, in this case, the bending rigidity of the sheet laminate d is also increased, and it may be difficult to wind the flexographic plate a around the plate cylinder, or the flexographic plate a may not be wound around the plate cylinder.

  The present invention has been devised in view of the above circumstances, and a flexographic plate that can be easily wound around a plate cylinder while increasing the thickness of an inner reinforcing layer, and a flexographic printing machine including the same. The purpose is to provide.

  Among the present inventions, the invention described in claim 1 is a sheet-like flexographic plate that is used by being wound around the outer peripheral surface of a substantially cylindrical plate cylinder, on the outer surface when wound around the plate cylinder. A sheet laminate in which a sheet-like surface print layer on which a transfer surface for printing is formed and a sheet-like inner reinforcing layer disposed on the inner surface side of the surface print layer are laminated, and the sheet laminate By holding both ends in the circumferential direction of the plate cylinder, the sheet printing body includes a pair of holding means for preventing positional deviation between the surface print layer and the inner reinforcing layer at the holding position. Between the pair of holding means, the surface printed layer and the inner reinforcing layer are in a non-adhesive state capable of relative displacement.

  In the invention according to claim 2, the sheet laminate is provided with a through hole in each of the both end portions, and each holding means is a pin inserted into the through hole of the sheet laminate. The flexographic plate according to claim 1, comprising:

  Further, in the invention described in claim 3, the length L1 between the through holes at the both end portions of the surface printed layer is larger than the length L2 between the through holes at the both end portions of the inner reinforcing layer. 2 is a flexographic version.

  In addition, the invention according to claim 4 is the flexographic plate according to claim 2 or 3, wherein the surface laminate and the inner reinforcing layer are bonded in advance at the both ends of the sheet laminate. .

  The invention according to claim 5 is the flexographic plate according to any one of claims 1 to 4, wherein the inner reinforcing layer is made of a resin sheet or a metal sheet having a thickness t of 50 to 500 μm.

  The invention described in claim 6 includes the plate cylinder and the flexographic plate described in any one of claims 1 to 5 wound around the outer peripheral surface of the plate cylinder. It is a flexographic printing machine.

  According to a seventh aspect of the present invention, there is provided a first fixing means in which one of the holding means is fixed to the outer peripheral surface of the plate cylinder so as not to move, and the other holding means is the one holding means. The flexographic printing machine according to claim 6, further comprising a second fixing unit that is fixed to be movable toward and away from the printer.

The invention according to claim 8 is the difference L3 between the length L1 between the through holes at the both end portions of the surface printed layer and the length L2 between the through holes at the both end portions of the inner reinforcing layer. = L1-L2) is a flexographic printing machine according to claim 6 or 7, which satisfies the following formula (1).
0.85 ≦ {2πt × (θ / 360)} / L3 ≦ 1.15 (1)
Where t is the thickness of the inner reinforcing layer, and θ is the central angle (°) around which the sheet laminate is wound around the plate cylinder.

  The sheet laminate of the flexographic plate of the present invention is in a non-adhesive state in which the surface printing layer and the inner reinforcing layer can be displaced relative to each other between the pair of holding means. For this reason, when the flexographic plate is wound around the plate cylinder, the surface printing layer and the inner reinforcing layer are displaced from each other, and the rigidity of the entire sheet laminate is not excessively increased. Therefore, it is possible to easily wind the flexographic plate around the plate cylinder with a small force as compared with the conventional case. For example, the flexographic plate can be wound around the plate cylinder while increasing the thickness of the inner reinforcing layer and improving the durability of the inner reinforcing layer. That is, the flexographic plate of the present invention can dramatically improve the durability of the sheet laminate and can be easily wound around the plate cylinder.

  Moreover, according to this invention, a surface printing layer and an inner side reinforcement layer are a non-adhesion state. For this reason, when a deformation | transformation or damage arises in a surface printing layer or an inner side reinforcement layer, it becomes possible to remove a holding means and to replace | exchange only any one layer. As a result, the maintenance cost of the flexographic printing machine is reduced.

1 is a cross-sectional view of a flexographic printing machine in which an embodiment of the present invention is shown. FIG. 2 is a perspective view showing the plate cylinder of FIG. 1. It is a partially expanded perspective view in which the main part of the plate cylinder is shown. It is sectional drawing which expand | deployed the flexographic plate of FIG. It is a partial expanded sectional view of the flexographic plate wound around the plate cylinder. It is sectional drawing of the conventional flexographic plate.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a flexographic printing machine 1 using a flexographic plate 2 of the present embodiment. As shown in FIG. 1, the flexographic printing machine 1 includes a plate cylinder 3 and a flexographic plate 2. The plate cylinder 3 is formed in a substantially cylindrical shape. The flexographic plate 2 is used by being wound around the outer peripheral surface S of the plate cylinder 3.

  In the present embodiment, the flexographic printing machine 1 further includes an ink pan 4, an ink discharge roller 5, an anilox roller 6, and an impression cylinder 7. The ink pan 4 is a container filled with ink. A part of the outer surface of the ink discharge roller 5 is in contact with the ink of the ink pan 4. Therefore, the ink in the ink pan 4 is taken out from the ink pan 4 by the rotation of the ink discharge roller 5. A part of the outer surface of the anilox roller 6 is in contact with the outer surface of the ink discharge roller 5. Another part of the outer surface of the anilox roller 6 is in contact with the flexographic plate 2 of the plate cylinder 3. Therefore, the ink from the ink discharge roller 5 is supplied to the flexographic plate 2 of the plate cylinder 3 via the rotating anilox roller 6. The substrate 8 that passes between the plate cylinder 3 and the impression cylinder 7 is pressed by the impression cylinder 7 toward the plate cylinder 3 side.

  The ink supplied to the flexographic plate 2 is transferred to the substrate 8 by the rotation of the plate cylinder 3 in the circumferential direction F. The anilox roller 6 has appropriate means for adjusting the amount of ink supplied to the flexographic plate 2. The means may be, for example, a long blade (not shown) that is close to the outer surface of the anilox roller 6.

  As shown in FIG. 2 or FIG. 3, a mounting recess 10 is formed on the outer peripheral surface S of the plate cylinder 3. The mounting recess 10 is formed in a groove shape extending in the axial direction G of the plate cylinder 3. The mounting recess 10 is provided with a first fixing means 11 for fixing one end of the flexographic plate 2 and a second fixing means 12 for fixing the other end of the flexographic plate 2.

  The first fixing means 11 is provided on one side in the circumferential direction F of the mounting recess 10. One end of the flexographic plate 2 is fixed to the first fixing means 11 so as not to move. In this embodiment, the 1st adhering means 11 is a block shape long in the axial direction G formed in the bottom face 10a of the attachment recessed part 10. As shown in FIG. One end of the flexographic plate 2 is fixed to the first fixing means 11 by a plurality of bolts, for example.

  The second fixing means 12 is provided on the other side in the circumferential direction F of the mounting recess 10. For example, the other end of the flexographic plate 2 is fixed to the second fixing means 12 so as to be able to approach and separate from one end of the flexographic plate 2. In the present embodiment, the second fixing means 12 includes a guide rail 13 formed on the bottom surface 10 a of the mounting recess 10, a block 14 that is long in the axial direction G guided by the guide rail 13, and the block 14. Tension applying means 15 for applying tension to the flexographic plate 2. The other end of the flexographic plate 2 is fixed to the block 14 by, for example, a plurality of bolts.

  The block 14 is guided along the circumferential direction F on the bottom surface 10 a of the mounting recess 10 by the guide rail 13. In the present embodiment, the guide rail 13 includes a stopper (not shown) that holds the block 14 so as not to come off the guide rail 13.

  The tension applying means 15 includes, for example, a cylinder 15a and a rod 15b urged toward the inside of the cylinder 15a. As shown in FIG. In the tension applying means 15, the rear end of the cylinder 15 a is fixed to the bottom surface 10 a of the mounting recess 10 inside the mounting recess 10 from the guide rail 13. The tip of the rod 15b is fixed to the block 14. For this reason, the block 14 is urged toward the inside of the mounting recess 10 along the guide rail 13. The block 14 is preferably urged with a tension of 0.3 to 0.5 MPa per 20 mm length in the axial direction G.

  As shown in FIG. 3 or 4, the flexographic plate 2 includes a sheet laminate 20 in which a sheet-like surface printing layer 18 and a sheet-like inner reinforcing layer 19 are overlaid, and both ends of the sheet laminate 20. A pair of holding means 21 for holding the portions 20a and 20b is provided.

  In the present embodiment, the surface printing layer 18 includes a transfer layer 17 having a printing transfer surface 17 a and a base material 22 fixed to the inner surface side of the transfer layer 17. The substrate 22 is formed into a flexible sheet from a resin such as PET (polyethylene terephthalate) or PP (polypropylene). Further, the base material 22 is bonded to the inner surface of the transfer layer 17 by, for example, thermocompression bonding. For this reason, the base material 22 and the transfer layer 17 are fixed together without any relative displacement.

  The transfer layer 17 is formed of, for example, a material that is larger than the base material 22. The transfer layer 17 is formed in a sheet shape using an elastic material such as rubber or urethane resin, for example. Since the transfer layer 17 is in contact with the substrate 8, it is desirable that the transfer layer 17 be a softer material than the base material 22. The transfer layer 17 is formed on the outer surface side of the surface printing layer 18 when it is wound around the plate cylinder 3. On the outer surface of the transfer layer 17, printing convex portions that are transferred to the substrate 8 are formed.

  The inner reinforcing layer 19 is formed from a material such as resin or metal foil into a flexible sheet shape. The inner reinforcing layer 19 is made of, for example, a resin such as PET or PP, or a metal foil material such as SUS (stainless steel). The inner reinforcing layer 19 is disposed on the inner surface side of the surface printing layer 18, that is, on the base material 22 side. The inner reinforcing layer 19 is preferably made of a material that is equal to or less stretched than the base material 22.

  In the sheet laminate 20, the surface print layer 18 and the inner reinforcing layer 19 are not bonded between the pair of holding means 21. The surface printing layer 18 and the inner reinforcing layer 19 can be displaced relative to each other in the circumferential direction F. For this reason, when the flexographic plate 2 is wound around the plate cylinder 3, the surface printing layer 18 and the inner reinforcing layer 19 are displaced from each other, and the bending rigidity of the entire sheet laminate 20 is not excessively increased. Therefore, the flexographic plate 2 can be easily wound around the plate cylinder 3 with a small force as compared with the conventional case. Further, the flexographic plate 2 can be wound around the plate cylinder 3 while increasing the thickness of the inner reinforcing layer 19 and improving the durability of the inner reinforcing layer 19. That is, the flexographic plate 2 of this embodiment can dramatically improve the durability of the sheet laminate 20 and can be easily wound around the plate cylinder 3.

  The surface printed layer 18 and the inner reinforcing layer 19 are not bonded. For this reason, when deformation | transformation or damage arises in the surface printing layer 18 or the inner side reinforcement layer 19, it is possible to remove the holding means 21 and to replace only one layer 18 or 19. For this reason, the maintenance cost of the flexographic printing machine 1 is reduced.

  Each end 20a, 20b of the sheet laminate 20 is held by holding means 21, respectively. For this reason, relative displacement between the surface printing layer 18 and the inner reinforcing layer 19 at the holding position P is prevented. The holding position P means the position of the surface print layer 18 and the inner reinforcing layer 19 held by each holding means 21 at each end 20a, 20b of the sheet laminate 20.

  The end portions 20a and 20b of the sheet laminate 20 may be bonded in advance with an adhesive layer 29 such as an adhesive. In such a sheet laminate 20, the surface printing layer 18 and the inner reinforcing layer 19 are more reliably prevented from being displaced at the holding position P.

  The sheet laminate 20 is provided with a through hole 23 at each of the end portions 20a and 20b.

  Depending on the length of the sheet laminate 20 in the axial direction G and the load applied to the flexographic plate 2, a plurality of through holes 23 are preferably formed in the axial direction G. For example, 25 to 35 through holes 23 are formed in each of the end portions 20a and 20b in the axial direction G. When the number of the through holes 23 is small, the load acting on one through hole 23 is large, and the through holes 23 may be deformed at an early stage. When the number of through holes 23 is large, the load acting on each through hole 23 is dispersed, but the strength in the axial direction G in which the through holes 23 of the inner reinforcing layer 19 are formed decreases.

  As shown in FIG. 4, in the sheet laminate 20, the thickness t of the inner reinforcing layer 19 is desirably 50 to 500 μm. When the thickness t of the inner reinforcing layer 19 is smaller than 50 μm, the effect of reinforcing the sheet laminate 20 by the inner reinforcing layer 19 cannot be sufficiently obtained. Further, when the thickness t of the inner reinforcing layer 19 is larger than 500 μm, the rigidity of the sheet laminate 20 is increased, and the sheet laminate 20 is difficult to be bent, so that it is difficult to wind the flexographic plate 2 around the plate cylinder 3. Become. When the inner reinforcing layer 19 is formed from a resin such as PET or PP, the thickness t is more preferably 188 to 500 μm. Moreover, when the inner side reinforcement layer 19 is formed from metal foil, such as SUS, it is more preferable that the thickness t is 50-200 micrometers.

  The sheet laminate 20 is formed such that the length L1 between the through holes 23 in the circumferential direction F of the surface printed layer 18 is larger than the length L2 between the through holes 23 in the circumferential direction F of the inner reinforcing layer 19. preferable. When such a sheet laminated body 20 is wound around the plate cylinder 3, the bumps of the inner reinforcing layer 19 are suppressed.

As shown in FIG. 4 or FIG. 5, for example, the sheet laminate 20 has a difference L3 between a length L1 between the through holes 23 of the surface printed layer 18 and a length L2 between the through holes 23 of the inner reinforcing layer 19. (= L1-L2) preferably satisfies the following expression (1).
0.85 ≦ {2πt × (θ / 360)} / L3 ≦ 1.15 --- (1)
Where t is the thickness of the inner reinforcing layer 19 and θ is the central angle (°) around which the sheet laminate 20 is wound around the plate cylinder 3.

  In the formula (1), 2πt is generated in the surface printing layer 18 and the inner reinforcing layer 19 when the flexographic plate 2 having the inner reinforcing layer 19 having the thickness t is wound only once around the outer peripheral surface of the cylinder. This is the difference in length in the circumferential direction F. In this embodiment, since the plate cylinder 3 has the mounting recess 10, the flexographic plate 2 is wound around the plate cylinder 3 by an angle θ °. As a result, the difference L3 between the length L1 between the through holes 23 of the surface printed layer 18 and the length L2 between the through holes 23 of the inner reinforcing layer 19 is calculated by {2πt × (θ / 360)}.

  In the sheet laminate 20 satisfying the above formula (1), the flexographic plate 2 is wound around the plate cylinder 3 by forming the length L1 of the surface printing layer 18 in advance larger than the length L2 of the inner reinforcing layer 19. The looseness of the surface printed layer 18 or the inner reinforcing layer 19 when being applied is more reliably suppressed.

  As shown in FIG. 4, the holding means 21 is a vice including an upper block 25, a lower block 26, and an intermediate block 27 in the present embodiment, and is long along the axial direction G of the plate cylinder 3. The cross section is substantially U-shaped.

  The lower block 26 is fixed to the upper part of the block 14 of the first fixing means 11 or the second fixing means 12. The upper block 25 includes a lower surface 25 a that faces the upper surface 26 a of the lower block 26. The intermediate block 27 adjusts the distance between the upper surface 26 a and the lower surface 25 a between the upper block 25 and the lower block 26. The upper block 25 is fixed to the lower block 26 via the intermediate block 27 with, for example, bolts. The distance between the upper surface 26a and the lower surface 25a is adjusted to be, for example, smaller than the thickness of the sheet laminate 20, and the sheet laminate 20 is preferably compressed and held between the upper surface 26a and the lower surface 25a.

  A plurality of pins 28 are formed along the axial direction G on the upper surface 26 a of the lower block 26. Each pin 28 is inserted into the through hole 23 of the sheet laminate 20. Further, the top of the pin 28 is fitted into a hole formed in the upper block 25, for example. The pin 28 may be formed, for example, by fitting a long pin into a hole formed in the lower block 26.

  The holding means 21 more reliably prevents displacement of the surface print layer 18 and the inner reinforcing layer 19 at the holding position P by inserting each pin 28 into each through hole 23 of the sheet laminate 20. be able to.

As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect. In the present embodiment, one inner reinforcing layer 19 that is not bonded to the surface printed layer 18 is shown. The inner reinforcing layer 19 may be composed of, for example, a first inner reinforcing layer and a non-adhering second inner reinforcing layer adjacent to the inner side reinforcing layer. In this case, when the difference in length between the through holes of the first inner reinforcing layer and the second inner reinforcing layer is X and the thickness of the second inner reinforcing layer is Y, X is the following formula ( Satisfy 2). That is, the sheet laminated body 20 satisfying the following formula (2) can further include a plurality of inner reinforcing layers inside the inner reinforcing layer.
0.85 ≦ {2πY × (θ / 360)} / X ≦ 1.15 --- (1)
Where Y is the thickness of the second inner reinforcing layer, and θ is the central angle (°) around which the sheet laminate 20 is wound around the plate cylinder 3.

  In order to confirm the effect of the present invention, a flexographic plate having a basic structure shown in FIG. 4 was prototyped based on each specification. These prototype flexographic plates were wound around the plate cylinder of a test flexographic printing machine and tested. Table 1 shows the ease of winding the flexographic plate around the plate cylinder and the durability of the through holes during printing. For each flexographic plate, a base material made of PET and having a thickness of 438 μm was used.

  Further, as a comparative example, a flexographic plate having a basic structure shown in FIG. 6 was prototyped based on each specification and tested in the same manner as the flexographic plate of the present invention. The flexographic plates of the comparative examples do not have an inner reinforcing layer, and the base material is PET.

In addition, the common specification of each Example and each comparative example is as follows.
Plate cylinder diameter: 722.9 mm
Length of plate cylinder in axial direction: 1600mm
Angle θ at which the flexographic plate is wound: 322 °
Test printing machine: Alignment film printing machine (G6 size) manufactured by Nakan Techno
The test method is as follows.

<Easy winding around plate cylinder>
It was evaluated whether it was possible to wind the flexographic plate around the plate cylinder. The result shows that the flexographic plate that could be wound around the plate cylinder is “possible”, and the flexographic plate that could not be wound around the plate cylinder was shown as “impossible”.

<Durability of through holes>
Under the above conditions, flexographic printing was performed, and the number of printings until the through hole of the flexographic plate was damaged was measured. And durability of the through-hole of the flexographic plate based on this printing frequency was evaluated. The result is a comparison based on the number of times of printing of the flexographic plate of Comparative Example 1. “△” is not different from Comparative Example 1, “◯” is 1.2 times or more of Comparative Example 1, and “◎”. Indicates that it is 1.5 times better than Comparative Example 1.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the flexographic plate of the example could be wound around the plate cylinder, and the durability of the through hole was dramatically improved, and the durability of the flexographic plate was also greatly improved. did it.

DESCRIPTION OF SYMBOLS 1 Flexo printing machine 2 Flexo plate 3 Plate cylinder 8 To-be-printed object 10 Mounting recessed part 11 1st adhering means 12 2nd adhering means 17 Transfer layer 18 Surface printed layer 19 Inner reinforcement layer 20 Sheet laminated body 21 Holding means 23 Through-hole 28 Pin 29 Adhesive layer F Circumferential direction G Axis direction S Outer peripheral surface

Claims (8)

A sheet-like flexographic plate used by being wound around the outer peripheral surface of a substantially cylindrical plate cylinder,
A sheet-like surface printing layer having a printing transfer surface formed on the outer surface when wound around the plate cylinder, and a sheet-like inner reinforcing layer disposed on the inner surface side of the surface printing layer are overlaid. Sheet laminate,
as well as,
A pair of holding means for preventing displacement of the surface printed layer and the inner reinforcing layer at the holding position by holding both ends in the circumferential direction of the plate cylinder of the sheet laminate,
The flexographic printing plate according to claim 1, wherein the sheet laminate is in a non-adhesive state in which the surface printing layer and the inner reinforcing layer can be displaced relative to each other between the pair of holding means. The sheet laminate is provided with a through hole in each of the both end portions,
The flexographic printing plate according to claim 1, wherein each holding means includes a pin inserted into the through hole of the sheet laminate.   3. The flexographic printing plate according to claim 2, wherein a length L <b> 1 between the through holes at the both end portions of the surface printed layer is larger than a length L <b> 2 between the through holes at the both end portions of the inner reinforcing layer.   4. The flexographic printing plate according to claim 2, wherein the sheet laminated body has the surface printed layer and the inner reinforcing layer bonded in advance at both end portions. 5.   The flexographic printing plate according to any one of claims 1 to 4, wherein the inner reinforcing layer is made of a resin sheet or a metal sheet having a thickness t of 50 to 500 µm.   A flexographic printing machine comprising the plate cylinder and the flexographic plate according to claim 1 wound around an outer peripheral surface of the plate cylinder.   A first fixing means to which one of the holding means is fixed so as to be immovable is fixed to the outer peripheral surface of the plate cylinder, and the other of the holding means is fixed to the one holding means so as to be able to approach and separate. The flexographic printing machine according to claim 6, wherein a second fixing means is provided. A difference L3 (= L1−L2) between the length L1 between the through holes at the both end portions of the surface printed layer and the length L2 between the through holes at the both end portions of the inner reinforcing layer is expressed by the following equation (1). The flexographic printing machine according to claim 6 or 7, wherein:
0.85 ≦ {2πt × (θ / 360)} / L3 ≦ 1.15 (1)
Where t is the thickness of the inner reinforcing layer, and θ is the central angle (°) around which the sheet laminate is wound around the plate cylinder.

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