JP3984328B2 - Gravure printing plate and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gravure printing plate having good ink transfer and a method for producing the same .
[0002]
[Prior art]
Conventional gravure printing includes either (1) conventional gravure printing method, (2) direct gravure printing method (net gravure printing method), (3) net gravure printing method using tissue, or (4) engraving gravure printing method. The basic shape of the cell formed on the plate surface in these printing methods is the shadow part, halftone part, light part as shown in the basic form diagram of the cell in the conventional gravure printing plate of FIG. In this order, the volume of the cell decreases, and the cell area also decreases in this order except for the conventional gravure printing method.
The plane and cross-sectional shape of the cell differ from the other gravure printing methods (1) to (3) only in the engraving gravure printing method (4). In other words, the cell in the case of the engraving gravure printing method has a substantially quadrangular pyramid shape formed by engraving the plate surface by a stylus that vibrates up and down, whereas the cell in the case of other gravure printing methods is formed by corrosion. It is a saddle shape.
The ink transferability that the ink filled in these cells transfers to the substrate during printing includes the surface smoothness, compressibility, solvent absorbability, printing speed, type of solvent, printing pressure of the substrate. It is known that the shape of the cell itself is also greatly involved.
[0003]
[Problems to be solved by the invention]
In the case of a saddle-shaped cell formed by corrosion, the so-called “ink residue” phenomenon becomes noticeable due to poor ink transferability particularly in a portion exceeding 30 μm in the shadow portion and 10 μm in the highlight portion of the net gravure. However, this causes problems such as a decrease in print density that occurs as printing progresses, missing dots in highlights, roughness, and "doctor streaks" that occur when ink residues that have hardened in the cells are caught on the doctor. There is.
On the other hand, the ink transfer rate of the cell in the case of an engraving gravure printing plate using a heliocrigraph or the like is extremely excellent. Although the cell volume is generally 25% smaller than that of the corrosion forming cell, it can be seen that the transfer rate is good even when the density after printing is hardly changed.
However, with the engraving gravure printing plate, it is difficult to change the cell volume freely, the gradation expression tends to be monotonous, the density of the shadow part is limited, the roughness of the highlight part is conspicuous, and moire prevention due to the screen angle is prevented. There are drawbacks such as inability.
The present invention has been made in view of the above-mentioned problems, and has good ink transferability while being a corrosion method, prevents the above-mentioned problems caused by "ink residue", and enables stable printing. An object of the present invention is to provide a gravure printing plate that enables printing with rich gradation expression and eliminates the feeling of roughness in highlights.
[0004]
[Means for Solving the Problems]
The present invention has been made in order to solve the above problems, the cell of the polygonal pyramid or truncated pyramid shape formed by the inclined surface with a plurality of stages or undulations inclined toward the center from the periphery of the polygon, a predetermined An annular resist region and an annular non-resist region formed by using a concentric polygonal dot pattern having a line width of The gravure printing plate is characterized in that the area ratio of the non-resist region in the resist pattern decreases toward the outside from the center.
In addition, an annular resist region formed using a concentric polygonal dot pattern having a predetermined line width, and an annular non-resist region that decreases as the area ratio of the non-resist region goes outward from the center, Corrodes the resist pattern surrounding the center alternately, forming a polygonal pyramid or polygonal frustum-shaped cell formed by multiple steps inclined from the periphery of the polygon toward the center or a undulating inclined surface A method for producing a gravure printing plate, comprising:
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in more detail with reference to the drawings.
FIG. 1 is a perspective view showing one embodiment of a cell formed on a gravure printing plate according to the present invention.
As shown in FIG. 1, the shape of the cell 10 of the gravure printing plate according to the present invention is a quadrangular pyramid formed by a plurality of steps 5 or inclined surfaces with undulations 5 'inclined from the periphery of the quadrangle toward the center. It is a quadrangular frustum shape. Further, the center of the cell 10 which is the deepest portion does not necessarily need to be in the center and may be eccentric.
The shape of the cell 10 is similar to the cell of the engraving gravure printing plate (hereinafter referred to as “helio plate”) by a heliocrigraph, although the shape of the cell 10 is formed by corrosion, and the portion where the filled ink stays is small. In addition, the ink transferability is greatly improved as compared with a conventional saddle-shaped cell.
The array of cells 10 may be a gravure halftone dot arrangement or an offset halftone dot arrangement, but in the shadow portion, a normal gravure halftone dot arrangement as shown in FIG. 5 is used to obtain a printed matter having a high density and a wide density area. preferable.
A plurality of steps 5 or undulations are formed on the inclined surface. This inevitably occurs during the corrosion process of the gravure printing plate according to the present invention, and there are no printing problems due to these. Rather, the ink is moved from the outer periphery of the cell due to the centrifugal force generated by the rotation of the printing plate cylinder, and has the effect of preventing “blank” printing.
The cell 10 of the gravure printing plate according to the present invention is fundamentally different in that it is formed by corrosion unlike the helio plate. In addition, when the shape of the cell 10 is a helio plate, it is limited to a square and a rhombus, and the inclination angle of the inclined surface is limited to a substantially constant range, whereas the shape of the cell 10 is as shown in FIG. The shape is not limited to a quadrangle, and may be a rhombus, hexagon, octagon, or other polygon, or a circle or an ellipse. In addition, the cross-sectional shape such as the inclination and curvature of the inclined surface of the cell 10 can be considerably freely deformed by appropriately controlling the design of the dot pattern described later and the corrosion conditions.
[0006]
Hereinafter, the formation principle of the pyramidal or truncated pyramidal cell 10 by corrosion will be described with reference to FIGS.
FIG. 2 is an explanatory diagram of a dot pattern used for making a gravure printing plate according to the present invention.
2A to 2C show one embodiment of the dot pattern P in the shadow portion, halftone portion, and light portion, respectively.
The dot pattern P is a matrix pattern that is formed directly on the resist photosensitive layer formed by coating on the plate surface or by ON / OFF of a laser beam output from a dot generator to a photographic film as in the past.
As shown in FIG. 2, the dot pattern P used in the present invention is a concentric polygonal shape in which a plurality of annular patterns having a predetermined line width surround a common center point, and this dot pattern P is formed on the plate surface. The resist photosensitive layer is baked and developed to form a resist pattern R. Therefore, the resist pattern R is substantially the same as the dot pattern P in figure, and is composed of the resist region 2 and the non-resist region 3 from which the resist has been removed by development processing.
As shown in FIG. 2A, in the resist pattern R, the density of the non-resist region 3 increases at the center of the cell 10 and decreases toward the periphery.
In the shadow portion cell, as shown in FIG. 2A, the widths W1 to W4 of the non-resist region 3 have the following relationship, and the area ratio of the non-resist region 3 is directed outward from the center portion. It is getting smaller.
W1 <W2 <W3 <W4
As shown in FIGS. 2B and 2C, the cells in the halftone portion and the highlight portion naturally have a smaller number of annular patterns because the cell size becomes smaller. The area ratio is high.
[0007]
FIG. 3 is a diagram for explaining the principle of forming a cell of a gravure printing plate according to the present invention.
FIG. 3A is a cross-sectional view taken along the line xx ′ of FIG. 2A showing a state in which the resist pattern R is formed on the plate surface.
FIG. 3B is a cross-sectional view showing an intermediate process of corrosion, and FIG.
Corrosion by the corrosive liquid starts from the state shown in FIG. 3A and starts in the entire non-resist portion 3 on the surface of the copper plating layer 1 of the plate surface, but as shown in FIG. The central portion where the density of the portion 3 is large is most severely corroded, the depth is deeper, and side etching, which is lateral corrosion, also occurs more vigorously in the central portion and erodes the resist region 2. As a result, the bank portion 4 closer to the center disappears faster with the resist layer provided on the upper portion thereof, and the bank portion 4 is further corroded to become even more flat, and in the final stage shown in FIG. All the bank portions 4 are deformed in a step 5 or undulation 5 'shape, and an inclined surface that is inclined at a predetermined angle from the periphery toward the center is obtained, and the cell 10 has a quadrangular pyramid shape. If the non-resist region 3 at the center of the resist pattern R is made large, a quadrangular pyramid shape is obtained.
For comparison with the cell 10 obtained in this way, a saddle-shaped cell cross-section when corroded from a conventional halftone dot pattern is shown by the dotted line E in FIG.
As can be seen from FIG. 3 (c), the gravure printing plate cell 10 according to the present invention and the side wall of the conventional corrosion gravure printing plate cell have completely different shapes. This is because the degree of corrosion is controlled by the concentric polygonal resist region 2, and the shape of the inclined surface varies depending on the degree of change in the area ratio of the non-resist region 3 that changes from the center to the periphery. It can be deformed with a considerable degree of freedom.
For example, in a shadow portion where a high density is desired, the cell 10 is brought close to a conventional saddle shape as long as the above-described ink transfer is not impaired, and in the highlight portion, the cell 10 is wider and shallower than the conventional cell and has a gentle slope. Is possible.
In general, in making a gravure printing plate, a copper ballad plating layer is corroded with a corrosive liquid such as ferric chloride or a cupric chloride aqueous solution, and the copper plated layer is touched. Corrosion ability is high, and side etching becomes intense. Further, when the corrosive liquid is sprayed perpendicularly to the plate surface, side etching can be reduced. Therefore, by combining such corrosion conditions with the design conditions of the dot pattern P or resist pattern R described above, the cell 10 having a desired shape can be formed on the printing plate.
[0008]
FIG. 4 is an explanatory diagram of another embodiment of the cell formed on the gravure printing plate according to the present invention.
The shape of the cell 10 may be a polygonal pyramid shape with a decentered center as shown in FIG. 4 or a polygonal frustum shape.
In this molding, as shown in FIG. 4 (a), a resist pattern R having a shifted center point may be formed on the printing plate and corroded, and the yy ′ cross section after the corrosion is shown in FIG. 4 (b). As shown, the left and right side walls have different inclinations.
Accordingly, the behavior of the ink flow during printing inside the cell 10 changes, and the printing effect is different from that of the symmetrical cell 10 shown in FIG.
[0009]
It is the dot pattern P shown in FIG. 2 and the resist pattern R formed on the plate that dominates the shape of the cell 10 of the gravure printing plate according to the present invention.
In this dot pattern P, an original image is input in advance by an input scanner, and the digitized image data is subjected to image correction and endless correction (in the case of wood grain pattern) once on the CEPS display screen, Alternatively, it is formed directly on the resist photosensitive layer or on the plate-making film so as to form a desired dot pattern P in accordance with a program incorporated in advance by a laser beam from a dot generator of the imagesetter.
In this case, since the diameter of the laser beam that is ON / OFF controlled constitutes the minimum unit of the dot pattern P, the dot pattern P is a mosaic pattern in which the minimum units are gathered.
Accordingly, there are naturally restrictions on the fineness of the resist portion 2 or the non-resist portion 3, and the annular pattern cannot be increased without limitation.
Furthermore, outputting the dot pattern P as shown in FIG. 2 only to the specific density gradation area or specific section area of the screen can be freely performed by changing the computer program for controlling and modulating the laser beam. it can.
[0010]
【Example】
The gravure printing plate according to the present invention was applied to a wood grain pattern of a maple material for a decorative board having a large printing lot.
The cell structure has a quadrangular pyramid shape as shown in FIG. 1 over all gradations, and the dot pattern P as shown in FIG.
First, a film original image obtained by photographing a maple wood grain pattern is input to a computer by an input scanner and digitized, and after partial gradation correction, endless correction, etc. using application software, a laser stream plate making apparatus (Sink Laboratories Co., Ltd.) The number of lines of 150 lines / inch by a laser beam that is modulated ON / OFF directly by a computer to a positive photosensitive resist film coated on the plate cylinder surface from a dot generator. The dot pattern P was output while scanning with and developed to form a resist pattern R.
Next, using a ferric chloride aqueous solution with a specific gravity of 170 Baume, corrosion by a shower method was performed. As a result, a quadrangular pyramidal cell 10 similar to the Helio plate was formed over all gradations. The depth of the central part of the cell 10 was 33 μm, 28 μm, and 23 μm in the shadow part, the intermediate part, and the light part, respectively. Further, in the highlight portion, a cell 10 which is shallower and larger than a normal helio plate or a direct plate is obtained.
Next, using the gravure printing plate according to the present invention made as described above, gravure printing was performed under the following conditions, but as a result of comparison with the conventional direct plate, the ink transferability was good. During the printing process, the color density was not only stabilized from start to finish, but the gradation of the light portion became smooth and the roughness was lost. In addition, the gradation from the middle to the light part was particularly improved compared to the conventional Helio plate.
Printing lot: 10,000 m
Printing speed: 60 m / min Printing ink color tone: Light brown ink viscosity: 12 to 15 seconds [Zahn cup # 4]
[0011]
【The invention's effect】
According to the present invention, by using a concentric polygonal dot pattern in which a plurality of annular patterns having a predetermined line width surround a common center point, a polygonal pyramid or polygonal frustum shaped cell is formed by corrosion. The ink transfer rate is improved, troubles caused by the so-called ink residue are improved, and complaints due to color fluctuations, doctor streaks, etc. are eliminated in long-run printing, and printing loss can be reduced by stabilizing the quality. Can exert economic effects.
Furthermore, by adjusting the non-resist area 3 area from the periphery of the cell toward the center, the cell depth, inclination, or cross-sectional shape can be transformed into a desired shape, and the gradation is higher than that of the helio plate. Gravure printing with free expression and less roughness in the light part becomes possible.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a cell formed on a gravure printing plate according to the present invention. FIG. 2 is an explanatory view of a dot pattern used for plate making of a gravure printing plate according to the present invention. Fig. 4 is a diagram illustrating the principle of cell formation in a gravure printing plate. Fig. 4 is a diagram illustrating another embodiment of a cell formed in a gravure printing plate according to the present invention. Fig. 5 is a basic cell configuration diagram in a conventional gravure printing plate. Explanation】
DESCRIPTION OF SYMBOLS 1 Copper plating layer 2 Resist area | region 3 Non-resist area | region 4 Bank 5 Step 5 'Bump 10 Gravure printing plate cell E by this invention Gravure printing plate cell P by conventional corrosion P Dot pattern R Resist pattern

Claims (2)

A polygonal pyramid-shaped or polygonal frustum-shaped cell formed by a plurality of steps inclined from the periphery of the polygon toward the center or a undulating inclined surface forms a concentric polygonal dot pattern having a predetermined line width. An annular resist region and an annular non-resist region formed by use are formed by corroding a resist pattern surrounding a central portion alternately, and the area ratio of the non-resist region in the resist pattern is the center A gravure printing plate characterized in that the gravure printing plate becomes smaller toward the outside than the portion . An annular resist region formed using a concentric polygonal dot pattern with a predetermined line width and an annular non-resist region that decreases as the area ratio of the non-resist region goes outward from the center The resist pattern surrounding the central portion is corroded to form a polygonal pyramid-shaped or truncated pyramid-shaped cell formed by a plurality of steps inclined from the periphery of the polygon toward the center or an inclined inclined surface. A method for producing a gravure printing plate characterized by the above.

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