JP5063611B2 - Gravure printing plate - Google Patents

Description

  The present invention relates to a gravure printing plate used for gravure printing.

A general gravure printing plate is produced by the following process.
(B) Copper plating is performed using an aluminum or iron cylinder roll as a base material.
(B) Ballad plating is performed after copper plating (ballad plating can be omitted).
(C) After ballad plating, grindstone polishing.
(D) After grinding the grindstone, coat the photosensitive material.
(E) Dry.
(F) Laser exposure is performed with a laser exposure machine to form a gravure cell (a minute recess).
(G) By performing development, the photosensitive material in the laser-exposed portion (or the non-exposed portion) is removed.
(H) The photosensitive material in the portion is removed, the portion where the copper plating is exposed is corroded, and the necessary depth of the gravure cell is secured.
(I) Remove all photosensitive material.
(Nu) Chrome plating to increase the durability of the plate.
(L) Polish paper and remove chrome-plated protrusions.

  As a method for reproducing the density gradation of an image printed by the gravure printing plate produced as described above, a net gravure method for changing the area of the gravure cell of the gravure printing plate is known.

  The gravure printing roll is a roll in which a gravure cell in which density gradation (color shading) is expressed by the size of fine dots (halftone dots) is formed. As gravure cells (hereinafter sometimes simply referred to as cells) formed on a gravure platemaking roll, AM screen (Amplitude Modulation Screen) gravure cells and FM screen (Frequency Modulation Screen) gravure cells are known. In the AM screen, halftone dots are regularly arranged and density gradation is expressed by the size of the halftone dots, whereas in the FM screen, density gradation is expressed by the density of the halftone dots.

  In gravure printing, it is necessary to put ink into the gravure cell and scrape off excess ink with a doctor blade. Therefore, the area of the screen line in the shadow portion of the density gradation is 10% to 30%. That is, in the gravure plate making roll, the gradation of the gravure plate making roll is configured as a plate expressed by about 0 to 90% with respect to the gradation 0 to 100% of the printed matter.

  Here, the highlight part is the brightest part of the density gradation in which the cells are formed small, and the shadow part is the darkest part of the density gradation in which the cells are formed large. Is called halftone.

  Conventionally, for example, in a gravure plate in which a collection of concave cells is formed on a plate surface and the density gradation of an image is reproduced by a change in the area ratio occupied by the cell, the density gradation highlight portion and halftone portion There is known a gravure printing plate characterized in that the arrangement of cells is random and the arrangement of cells in the shadow portion is aligned (Patent Document 1).

  A conventional gravure cell is shown in FIGS. 5 and 6, the conventional gravure printing plate 100 has a pitch 120 determined according to the number of lines / inch. For example, in the case of 175 lines / inch, one pitch is 145 μm. A gravure cell 140 is formed in each pitch 120, and ink is put into the gravure cell 140, and excess ink is scraped off and printed by a doctor blade.

  In the net gravure method, since the density is adjusted depending on the area of the gravure cell, the size of the gravure cell 140 is changed according to the density gradation. FIG. 5 is a schematic top view of a gravure cell formed on a conventional gravure printing plate, in which (a) is a density gradation 5% state, (b) is a density gradation 10% state, and (c). Is a state where the density gradation is 30%, and (d) is a state where the density gradation is 45%, and FIG. 6 is also a schematic top view of a gravure cell formed on a conventional gravure printing plate. ) Shows a state of density gradation 50%, (f) shows a state of density gradation 70%, and (g) shows a state of density gradation 90%.

  However, since the conventional gravure cell has a square lattice shape as shown in FIGS. 5A to 5D and FIGS. 6E to 6G, the gravure cell is printed with ink. Then, the image becomes flat in the printing direction, the inks in the gravure cell interfere with each other, the interference part becomes conspicuous, the appearance of the intermediate color deteriorates, and the gradation is smooth There was a problem of lacking in size.

  This problem is particularly noticeable in the AM screen. Since gravure cells are regularly arranged on the AM screen, the interference between the halftone dots starts to occur at the same time, and the interference portion becomes conspicuous.

On the other hand, in the FM screen, gravure cells are formed at random, so that the interference between the halftone dots is random. Therefore, the interference between the halftone dots as described above hardly occurs, and the interference portion of the halftone dots is not conspicuous. However, in the case of the FM screen, there is a problem in that the transfer of ink to the highlight portion is poor, printing is conspicuous, and sufficient density cannot be obtained in the shadow portion.
JP-A-8-146594

  As a cause of the above problem, the present inventors have made extensive studies and found out that a printing roughness or a gradation step occurs at the part where dots on the top, bottom, left and right start to be connected when printing. It was.

The present invention has been made in view of the above problems, and not only can improve the appearance of intermediate colors and the smoothness of gradation in an AM screen, but also improve the transfer of ink to the highlight portion of an FM screen. In addition, an object of the present invention is to provide a gravure printing plate capable of obtaining a sufficient density in a shadow portion.

In order to solve the above problems, the gravure printing plate of the present invention is
A gravure printing plate for printing an image having a density gradation consisting of a highlight part, a halftone part and a shadow part,
The top surface shape of the cell of the gravure printing plate,
Forming a band-shaped highlight portion main cell having a small area in the highlight portion;
In the halftone portion, the area of the band-shaped highlight section main cell is gradually increased so that both ends of the band-shaped highlight section main cell approach each other as the density gradation increases, and the band-shaped highlight section main cell Forming a band-like halftone main cell by additionally forming a dot-like or linear halftone auxiliary cell around the
As the density gradation increases in the shadow portion, the area of the band halftone main cell is gradually increased to form an annular shadow portion main cell by joining both end portions of the band halftone main cell. It is characterized by doing.

  By configuring the highlight portion as described above, it is possible to cover the same print area as a conventional grid cell with a small area of cells, and to reduce the spot density.

  In the halftone portion, as described above, by forming one or more auxiliary cells of points and lines, it is possible to make the dot connection portion inconspicuous.

  The annular shadow portion main cell may be an annular cell having an island formed in the center, or may not be completely an island but a peninsula. In conventional screens, printing unevenness sometimes occurs when the density gradation is 50% to 100%. In this way, in the shadow part, the printing unevenness is improved by forming an island or peninsula in the center. The Further, the halftone portion auxiliary cell may be in contact with the annular shadow portion main cell, or may be positioned apart without contacting.

  The halftone auxiliary cell may be gradually reduced in size as it approaches the shadow portion (density gradation 50% or more), or the halftone auxiliary cell itself may be extinguished.

  Further, in the shadow portion, the halftone auxiliary cell may be used as a shadow portion auxiliary cell by increasing its area as the density gradation increases.

  Further, the band-shaped highlight main cell, the band-shaped halftone main cell and halftone auxiliary cell, and the shadow main cell and shadow auxiliary cell may be formed by a large number of minute pits. It is.

  The size of the minute pits is preferably 5 μm to 100 μm, and particularly preferably 20 μm to 50 μm.

  Here, the highlight portion is a portion having the lightest color density of the printed material, the shadow portion is the darkest portion, and the halftone portion indicates an intermediate portion thereof. In the present specification, the highlight portion refers to a portion having a density gradation of 30% or less, and the shadow portion refers to a portion having a density gradation of 50% or more. It refers to 10 to 70% gradation.

  The depth of the gravure cell of the gravure printing plate of the present invention varies depending on the desired printing and is not particularly limited. For example, a depth of 1 μm to 150 μm is possible.

  Further, the number of screen lines applicable to the gravure printing plate is not particularly limited. For example, a number of lines such as 10 lines / inch to 1500 lines / inch can be applied, and the size of each cell can be determined according to the number of lines. Fluctuates.

  According to the gravure printing plate of the present invention, not only the appearance of the intermediate color and the smoothness of gradation in the AM screen can be improved, but also the transfer of ink to the highlight portion in the FM screen is improved and the shadow portion is improved. There is a remarkable effect that a gravure printing plate capable of obtaining a sufficient concentration can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is upper surface schematic explanatory drawing of the gravure cell formed in the gravure printing plate which is one embodiment of this invention, Comprising: (a) is the state of density | concentration gradation 5%, (b) is density | concentration gradation 10%. A state, (c) shows a state with a density gradation of 30%, and (d) shows a state with a density gradation of 45%. It is a top schematic explanatory drawing of the gravure cell formed in the gravure printing plate which is one embodiment of this invention, Comprising: (e) is the state of density | concentration gradation 50%, (f) is density | concentration gradation 70%. The state, (g) shows the state of density gradation 90%. It is the upper surface schematic explanatory drawing of the gravure cell formed in the gravure printing plate which is other embodiment of this invention, Comprising: (a) is the state of density | concentration gradation 5%, (b) is density | concentration gradation 10%. A state, (c) shows a state with a density gradation of 30%, and (d) shows a state with a density gradation of 45%. It is a top schematic explanatory drawing of the gravure cell formed in the gravure printing plate which is other embodiment of this invention, Comprising: (e) is the state of density | concentration gradation 50%, (f) is density | concentration gradation 70%. The state, (g) shows the state of density gradation 90%. It is a schematic top view of a gravure cell formed on a conventional gravure printing plate, where (a) is a density gradation 5% state, (b) is a density gradation 10% state, and (c) is a density scale. The tone is 30%, and (d) shows the density gradation is 45%. It is a top schematic explanatory drawing of the gravure cell formed in the conventional gravure printing plate, (e) is a state of density gradation 50%, (f) is a state of density gradation 70%, (g) is a density step. The state of 90% tone is shown.

Explanation of symbols

10A, 10B: Gravure printing plate of the present invention, 12, 52: Pitch, 14, 54: Strip highlight part main cell, 16, 56: Halftone auxiliary cell, 18, 58: Strip halftone main cell, 20 , 60: annular shadow part main cell, 22, 62: shadow part auxiliary cell, 24, 64: island, 53: minute pit, 100: conventional gravure printing plate, 120: pitch, 140: gravure cell.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the illustrated examples are shown by way of example, and it goes without saying that various modifications can be made without departing from the technical idea of the present invention. .

  1A and 1B are schematic top views of a gravure cell formed on a gravure printing plate according to an embodiment of the present invention, in which FIG. 1A shows a state where the density gradation is 5%, and FIG. The tone is 10%, (c) is the density gradation 30%, and (d) is the density gradation 45%. FIG. 2 is a schematic top view of a gravure cell formed on a gravure printing plate according to an embodiment of the present invention, where (e) is a density gradation 50% state and (f) is a density scale. The tone is 70%, and (g) is the density tone of 90%.

  FIG. 3 is a schematic top view of a gravure cell formed on a gravure printing plate according to another embodiment of the present invention, where (a) is a state with a density gradation of 5%, and (b) is a density level. The tone is 10%, (c) is the density gradation 30%, and (d) is the density gradation 45%. FIG. 4 is a schematic top view of a gravure cell formed on a gravure printing plate according to another embodiment of the present invention, where (e) is a density gradation 50% state and (f) is a density scale. The tone is 70%, and (g) is the density tone of 90%.

  FIG. 5 is a schematic top view of a gravure cell formed on a conventional gravure printing plate, in which (a) is a state with a density gradation of 5%, (b) is a state with a density gradation of 10%, (c ) Shows a state with a density gradation of 30%, and (d) shows a state with a density gradation of 45%. FIG. 6 is a schematic top view of a gravure cell formed on a conventional gravure printing plate, where (e) is a state with a density gradation of 50%, (f) is a state with a density gradation of 70%, (g ) Shows a state of density gradation 90%.

  The gravure printing plate of the present invention is prepared by the following steps. First, copper plating is performed using a cylinder roll of aluminum, iron, or CFRP (carbon fiber reinforced resin) as a base material. After copper plating, ballad plating is performed (ballad plating can be omitted). After ballad plating, grindstone is polished. After grinding the grindstone, the photosensitive material is coated. Then dry. Then, laser exposure is performed by a laser exposure machine to form a gravure cell (a minute recess). By performing development, the photosensitive material in the laser-exposed portion (or the non-exposed portion) is removed. The portion of the photosensitive material is removed, the portion where the copper plating is exposed is corroded, and the necessary depth of the gravure cell is secured. Remove all photosensitive material. Hard plate treatment (for example, chrome plating, DLC (Diamond Like Carbon) film, nickel alloy film, silicon dioxide film, etc.) is performed to increase the durability of the plate. Then, paper polishing is performed to remove the protrusions on the hard film.

  The gravure cell of the gravure printing plate thus formed will be described with reference to FIGS. In forming the gravure cell of the gravure printing plate of the present invention, as shown in the figure, it is preferable to flatten in the direction perpendicular to the printing direction in order to prevent the image from becoming an ellipse during printing.

  FIG. 1 shows a schematic top view of a gravure cell formed on a gravure printing plate according to one embodiment of the present invention. 1 and 2, reference numeral 10A denotes an embodiment of the gravure printing plate of the present invention. Reference numeral 12 denotes a pitch, and the size of the pitch 12 is determined according to the number of screen lines to be printed. In the illustrated example, the case of 175 lines / inch is shown, and the pitch 12 is 145 μm.

  The gravure printing plate 10A of the present invention is a gravure printing plate for printing an image having a density gradation composed of a highlight portion, a halftone portion, and a shadow portion.

  In the illustrated example, the case where the density gradation is less than 10% is the highlight portion, the density gradation of 10% to less than 50% is the halftone portion, and the density gradation of 50% or more is the shadow portion. As described above, the highlight portion refers to a portion having a density gradation of 30% or less, and the shadow portion refers to a portion having a density gradation of 50% or more. This means a gradation of 10 to 70%.

  First, in the highlight portion, a band-like highlight portion main cell 14 having a small area is formed (FIG. 1A, density gradation 5%).

  Next, in the halftone portion, the area of the band-shaped highlight main cell 14 is gradually increased so that both ends of the band-shaped highlight main cell 14 are close to each other as the density gradation increases. A band-shaped halftone main cell 18 is formed by additionally forming a dotted halftone auxiliary cell 16 around the highlight main cell 14 (FIGS. 1B to 1D). Density gradation 10% to 45%).

  Further, in the shadow portion, as the density gradation increases, the area of the band-shaped halftone main cell 18 is gradually increased to join the both ends of the band-shaped halftone main cell 18 to join the annular shadow portion. The main cell 20 is formed (FIGS. 2E to 2G).

  Further, in the shadow portion, the area of the halftone auxiliary cell 16 is increased as the density gradation increases, thereby forming the shadow portion auxiliary cell 22 (FIGS. 2E to 2G).

  The annular shadow main cell 20 is an annular cell in which an island 24 is formed at the center, as shown in FIGS.

  In FIG. 2 (f), the shadow part auxiliary cell 22 is configured to contact the annular shadow part main cell 20. In FIG. 2G, the shadow part auxiliary cell 22 is combined with the annular shadow part main cell 20 and is included in the annular shadow part main cell 20.

  When gravure printing is performed using the gravure printing plate 10A configured as described above, the appearance of intermediate colors and the smoothness of gradation on the AM screen can be improved. Further, when applied to an FM screen, the transfer of ink to the highlight portion on the FM screen can be improved and a sufficient density in the shadow portion can be obtained.

  3 and 4 show schematic top views of a gravure cell formed on a gravure printing plate according to another embodiment of the present invention. 3 and 4, reference numeral 10B denotes another embodiment of the gravure printing plate of the present invention. Reference numeral 52 denotes a pitch, and the size of the pitch 52 is determined according to the number of screen lines to be printed. In the illustrated example, the case of 175 lines / inch is shown, and the pitch 52 is 145 μm.

  The gravure printing plate 10B of the present invention is a gravure printing plate for printing an image having a density gradation composed of a highlight portion, a halftone portion and a shadow portion. The gravure cell of the gravure printing plate 10 </ b> B is composed of a large number of minute pits 53.

  In the illustrated example, the case where the density gradation is less than 10% is the highlight portion, the density gradation of 10% to less than 50% is the halftone portion, and the density gradation of 50% or more is the shadow portion. As described above, the highlight portion refers to a portion having a density gradation of 30% or less, and the shadow portion refers to a portion having a density gradation of 50% or more. This means a gradation of 10 to 70%.

  First, in the highlight part, a band-like highlight part main cell 54 having a small area is formed by the minute pits 53 (FIG. 3A, density gradation 5%).

  Next, in the halftone portion, the area of the band-like highlight main cell 54 is gradually increased by the minute pits 53 so that both ends of the band-like highlight main cell 54 come close as the density gradation increases. In addition, a band-like halftone main cell 58 is formed by additionally forming a dot-like or linear halftone-auxiliary cell 56 with minute pits 53 around the band-like highlighted portion main cell 54 (FIG. 3B). ) To (d), density gradation 10% to 45%).

  Further, in the shadow portion, as the density gradation increases, the area of the band-shaped halftone main cell 58 is gradually increased by the minute pits 53 to join both ends of the band-shaped halftone main cell 58. Thus, the annular shadow main cell 60 is formed (FIGS. 4E to 4G).

  Further, in the shadow part, the area of the halftone auxiliary cell 56 is increased by the minute pits 53 as the density gradation increases, thereby forming a shadow part auxiliary cell 62 (FIGS. 4E to 4G). ).

  The annular shadow main cell 60 is an annular cell in which an island 64 is formed at the center, as shown in FIGS.

  In FIG. 4 (f), the shadow portion auxiliary cell 62 is in contact with the annular shadow portion main cell 60. In FIG. 4G, the shadow part auxiliary cell 62 is combined with the annular shadow part main cell 60 and is included in the annular shadow part main cell 60.

  As shown well in FIG. 4, the strip-shaped highlight main cell 54, the strip-shaped halftone main cell 58 and the halftone auxiliary cell 56, the shadow main cell 60 and the shadow portion auxiliary cell 62 of the gravure printing plate 10B are as follows. It is formed with a large number of minute pits 53.

  When the gravure printing is performed using the gravure printing plate 10B configured as described above, not only the appearance of the intermediate color and the smoothness of gradation in the AM screen can be improved, but also the ink to the highlight portion in the FM screen. As a result, it was possible to obtain a sufficient concentration in the shadow portion.

Claims (3)

A gravure printing plate for printing an image having a density gradation consisting of a highlight part, a halftone part and a shadow part,
The top surface shape of the cell of the gravure printing plate,
Forming a band-shaped highlight portion main cell having a small area in the highlight portion;
In the halftone portion, the area of the band-shaped highlight section main cell is gradually increased so that both ends of the band-shaped highlight section main cell approach each other as the density gradation increases, and the band-shaped highlight section main cell Forming a band-like halftone main cell by additionally forming a dot-like or linear halftone auxiliary cell around the
As the density gradation increases in the shadow portion, the area of the band halftone main cell is gradually increased to form an annular shadow portion main cell by joining both end portions of the band halftone main cell. A gravure printing plate characterized by   2. The gravure printing plate according to claim 1, wherein in the shadow portion, the area of the halftone auxiliary cell is increased as the density gradation increases, thereby forming a shadow portion auxiliary cell.   2. The band-shaped highlight main cell, the band-shaped halftone main cell and halftone auxiliary cell, and the shadow main cell and shadow auxiliary cell are formed by a large number of minute pits. Or the gravure printing plate of 2.

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