JPH10157273A - Gravure printed matter and printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit gravure printing, reduced in the fluctuation of color tone, stabilized in quality and reduced in spoilage, in long-run printing, by a method wherein a projected part is provided in a cell and a non-inked part is formed at the inside of the inked part profile line of a halftone dot pattern. SOLUTION: A projected part is provided at the central part of a cell. Then, a hollow pattern, having non-padding part N at the inside of the padding part profile line of halftone dot formed by the shift of ink from the cell, is formed. According to this method, the fluctuation of printing color affected by the change of diameter of halftone dot due to the change of viscosity of ink under printing can b mitigated physically by the provision of the hollow part whereby the behavior of ink, transferred from the cell to the printed matter, is stabilized and the halftone dot, having a diameter in accordance with the size of the cell, can be readily formed even when the viscosity of the ink is changed. On the other hand, the fluctuating ratio of the halftone dot area is reduced by the existence of the hollow pattern whereby the variation of printing color can be reduced and the quality of the printed matter can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gravure printed matter and a gravure printing plate for suppressing variations in color tone within a lot when performing long-run gravure printing.

[0002]

2. Description of the Related Art Conventional gravure printing employs any one of conventional gravure printing, direct gravure printing (net gravure printing), and engraving gravure printing. As shown in the basic shape diagram of the cell in the conventional gravure printing plate of FIG. 1, the volume of the cell decreases in the order of the shadow portion, the medium portion, and the light portion, and the transfer amount of the ink to the printing material is reduced. And the area of the halftone dots formed by the transferred ink is also small except for conventional gravure printing. On the printing material gravure-printed by these gravure printing plates, differences occur due to differences in plate type, printing conditions, conditions of the ink receiving surface, etc., but are shown in the halftone dot pattern diagram of the conventional gravure printed matter of FIG. Is formed. The diameter of a halftone dot (shadow dot) in the shadow portion is 150 to 200 μm when scanned at 150 lines / inch, and is about 20 to 60 μm in a halftone dot (light dot) in the light portion. Density gradation of a specific color is formed by such halftone dots, and a target color tone is reproduced by multiplying halftone dots of a specific color alone or a plurality of colors. When a pattern such as a decorative board for building materials is printed by gravure printing, it is necessary to match the printing color to a standard color at the final stage. For that purpose, the following method has been adopted. (1) Change the ink viscosity to change the area of the dot pattern. (2) Change the printing pressure to change the area of the dot pattern. (3) Adjust the color tone of the ink itself. (Dilution with solvent,
The ratio of the amount of added medium is changed. (4) Combine the methods (1) to (3).

[0003]

However, the following can be cited as factors that cause the printing color once subjected to color matching on a printing press to fluctuate. Poor accuracy of the printing machine itself Insufficient printability of the printing material Decrease in ink transfer due to clogging of cells Decrease in cell capacity due to wear of printing plate Decrease in shear force of ink on plate due to abrasion of doctor Halftone dot due to fluctuation in ink viscosity Change in diameter Among the above, the change in dot diameter due to fluctuations in ink viscosity is due to the fact that when ink viscosity decreases during printing, halftone dots tend to become large, visually appearing darker in color, and conversely during printing. As the ink viscosity increases, the halftone dots become smaller, resulting in a color appearing lighter, and there is a problem that it is difficult to control regardless of the largest cause of printing color variation. The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a gravure print having halftone dots that reduces variation in printing color in long-run printing, and a gravure printing plate easily forming such halftone dots. I do.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a gravure printing plate in which an aggregate of cells forming an image portion is formed on a printing plate, and a total density is obtained. In at least a part of the density gradation area of the gradation or at least a part of the area of the screen, a non-inlaid part is formed inside the inlaid part outline of a halftone dot pattern formed by transferring ink from individual cells. Or the non-inlaid portion penetrates the contour line of the halftone dot pattern and is connected to an external non-image portion to form a dot-shaped concave portion forming an image portion. Are formed on the printing plate, and at least one or more convex portions are formed inside each of the cells in at least a part of the density gradation area of the entire density gradation or at least a part of the divided area of the screen. Is formed.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the drawings. FIG. 3 is an explanatory diagram of a halftone dot pattern of a gravure print according to the present invention. As shown in FIG. 3 (a), the halftone dots of the gravure printed matter according to the present invention have a non-thick portion N inside a nonthick portion contour line of a halftone dot formed by transferring ink from one cell. Has a hollow pattern. The position of this hollow pattern need not necessarily be at the center of the halftone dot, and as shown in FIG. 3B, is shifted so as to be connected to the non-image portion outside the halftone dot and has a notch. It may be a pattern. In the gravure printed matter according to the present invention, the above-described non-inlaid portion N (hereinafter, referred to as a hollow portion).
Are provided in all density gradations or limited to a specific gradation region. For example, shadows and lights may be normal halftone dots, and a hollow halftone dot may be formed in about one third of the halftone area. Further, only a specific divided area of the screen may be a halftone dot with a hollow.

The gravure printed matter according to the present invention, which is printed with halftone dots, is stable in a large lot of printed matter in long-run printing of several thousand meters or more with less variation in printing color. This is because the variation in printing color caused by the change in halftone dot diameter caused by the change in the viscosity of the ink during printing can be physically reduced by providing the hollow portion. That is, by providing a hollow part,
This is because the behavior of the ink transferred from the cell to the printing material is stabilized, and even when the viscosity of the ink changes, a halftone dot having a diameter corresponding to the size of the cell is easily formed. In addition, although the change in the diameter of the halftone dot still remains in practice, the variation ratio of the halftone dot area is reduced due to the presence of the hollow pattern, which reduces the variation in printing color and stabilizes the quality of printed matter. It is connected to the effect. As shown in FIGS. 3A and 3B,
The hollow N is remarkable in the shadow dot and the medium dot. However, in the light dot, the state of the hollow N becomes difficult to recognize, and the difference from the conventional cell may be lost. However, even if the light dot does not have the hollowing effect, the target region for stabilizing the color tone is mainly a shadow and a halftone, and does not hinder much.

FIG. 4 is an explanatory view of a gravure printing plate according to the present invention. FIG. 4A is a plan view of a cell of a printing plate according to the present invention. The printing plate according to the present invention, as described below,
A convex portion is provided at the center of the cell to easily form a hollow N. Therefore, in the case of the direct gravure printing plate, similarly to the conventional gravure printing plate, the cell size is not varied according to the density gradation, and the area of the convex portion forming the hollow N is controlled to control the density gradation. The tone may be displayed. Also, as shown in FIG. 1B, a difference in cell size is provided according to the density gradation, as in a conventional direct gravure printing plate, and a further convex portion is formed in the cell. It may be. Fig. 4 (b)-
(E) is a cross-sectional view of a cell of the gravure printing plate according to the present invention having a structure that easily causes hollow N. While the bottom of the conventional cell is flat or curved somewhat in a bowl shape, the cell of the gravure printing plate according to the present invention has at least one or more convex portions T at the bottom, The convex portion T promotes the above-described hollow phenomenon, and at the same time, according to the size occupied in the cell,
It is possible to configure a density gradation.

In the plate making method of the gravure printing plate according to the present invention, a resist film is formed on the surface of a gravure printing plate made of a material such as copper as in the conventional direct gravure plate making method, and direct etching is performed. However, using a laser beam scanned by computer control, a non-resist indicated by a white portion as shown in FIG. 4 (c ') is placed on a gravure printing plate coated with a photosensitive film for resist formation from a dot generator. What is necessary is just to output with the dot of pattern RP. FIG. 4C shows a cross section of a cell obtained by directly etching the non-resist pattern RP.
It is shown in. Further, as shown in FIGS. 4E and 4E, the density gradation can be formed by changing the area of the resist portion at the center of the dot. Further, it is possible to output dots such as (c ′) and (a ′) only to a specific density gradation area or a specific section area of the screen by changing a computer program for controlling and modulating a laser beam. Can be done. Further, the gravure printing plate making method according to the present invention can be performed by a conventional gravure plate making method using a carbon tissue. In this case, the above-mentioned dots may be output to the carbon tissue using, for example, an ultraviolet laser or the like, and the exposed carbon tissue may be transferred onto a plate surface. Then, in the case of a non-resist part formed on the plate surface or in the case of carbon tissue, the cell is corroded by using a corrosive solution such as an aqueous ferric chloride solution through a resist film having a different thickness generated according to the exposure ratio. You only need to engrave.

The cell depth of the gravure printing plate according to the present invention and the cross-sectional shape of the convex portion T formed in the center portion depend on the resist pattern formed on the plate surface and the etching conditions, as shown in FIGS. Can be changed as shown in FIG. Further, as shown in FIGS. 4B and 4C, the height of the convex portion T in the shadow cell may be changed. Convex part T
If is slightly lower than the surrounding bank, the hollow area will not be a complete white area, but will have substantially the same effect. FIG.
The delicate gradation in the light portion is reproduced by the minute cells provided in the convex portion as shown in FIG. 4E, and the diameter of the non-resist pattern RP of the minute cells shown in FIG. It is about.

[0010]

EXAMPLE FIG. 4 (c) shows a direct gravure plate-making method for a shadow portion and a halftone portion of a printing plate of a grain pattern and a base pattern of a teak material for a melamine decorative board, respectively.
A gravure printing plate having a cross-sectional structure as shown in (d) was produced. First, digitize the image gradation of the film taken from the wood grain board original with a scanner, import it to a computer, and correct it using application software.
The plate-collecting is performed, and the above-mentioned hollow resist pattern is exposed (output) while scanning with a laser beam whose intensity and ON / OFF are modulated by a computer with respect to a positive photosensitive resist film applied to a copper cylinder surface from a dot generator. ) And developed to form a resist pattern, and finally the cylinder was corroded using a corrosive solution comprising an aqueous ferric chloride solution. As a result, FIG.
The cell group having a convex portion at the center as shown in (c) and (d) could be stamped. Then, gravure printing was performed under the following conditions to prepare an example sample. Printing lot: 10,000 m Printing speed: 60 m / min Ink viscosity: 12 to 15 seconds [Zahn cup # 4] Target ink density: Shadow part: 1.1 Halftone part: 0.6 The gravure printing was performed at approximately the same density as described above using a plate having a halftone dot structure as described above, to obtain a comparative sample. In the color density measurement of the sample of the example and the sample of the comparative example, one point was selected from a shadow portion on the cylinder plate surface and set as a measurement point, and this point was measured every 500 m by a spectrophotometer (FMC-2 color difference type, D65). (Light source), and the color difference ΔE from the reference color matched at the start of printing was determined. As a result, in the comparative example, ΔE was 2.
Whereas, in the case of the embodiment, ΔE was 1.0.
Within. That is, it has been clarified that the printing color is extremely stable, long-run printing with little color tone variation is possible, and printing loss can be reduced.

[0011]

According to the present invention, a gravure printed matter with little color tone fluctuation can be obtained in long-run printing by forming a halftone dot with a hollow by providing a convex portion inside the cell. , Along with stable quality,
An economic effect of reducing printing loss can be exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic shape of a cell in a conventional gravure printing plate.

FIG. 2 is a halftone dot pattern diagram in a conventional gravure print.

FIG. 3 is an explanatory diagram of a halftone dot pattern of a gravure print according to the present invention.

FIG. 4 is an explanatory view of a gravure printing plate according to the present invention.

[Explanation of symbols]

 N Hollowout T Convex part RP Resist pattern

Claims (3)

[Claims] An aggregate of cells forming an image portion is printed from a gravure printing plate formed on a printing plate, and at least a part of a density gradation region of a total density gradation or at least one of a screen. A gravure printed matter, characterized in that a non-inlaid portion is formed inside the inlaid portion contour of a halftone dot pattern formed by transferring ink from individual cells in the divided region of the portion. 2. The gravure printed matter according to claim 1, wherein the non-inlaid portion penetrates the contour line of the halftone dot pattern and is continuous with an external non-image portion. 3. An aggregate of cells in the form of halftone dots forming an image portion is formed on a printing plate, and a density gradation area of at least a part of the entire density gradation or at least a part of the screen is formed. A gravure printing plate, wherein at least one or more convex portions are formed inside each of the cells in the partitioned region.