JPH07329440A - Dot gravure printing plate - Google Patents

Abstract

PURPOSE:To improve the transfer of ink to paper from cells and to enhance a density gradient by matching two diagonal line directions with a doctor tangential direction and the direction crossing the same at a right angle with respect to cells wherein dot % is up to specific %. CONSTITUTION:Cells wherein the dot % due to laser exposure scanning is smaller than about 31% have a shape long in the direction crossing a doctor tangential direction at a right angle and cells wherein dot % is smaller than about 56% are diamond cells. Cells wherein dot % is about 31 - below about 56% have a hollowed-out diamond ring shape same to the shape of cells wherein an outer peripheral contour is about 56%. One diagonal line direction of cells wherein dot % is about 31-56% becomes the direction crossing the doctor tangential direction at a right angle. Cells wherein dot % is larger than about 56% are diamond cells and one side of each of the cells coincides with a cell right oblique arranging direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the dispersion of ink from a highlight portion to a halftone portion when a yellow plate, a magenta plate, a cyan plate and a black plate are prepared from color separation information of a plate original and color printed. The present invention relates to a halftone gravure printing plate that has high properties, can eliminate moire that may occur due to overprinting of three colors or four colors, has good transferability of ink in the highlight part, and can improve the gradation degree of light and shade.

[0002]

2. Description of the Related Art FIG. 4 shows a halftone gravure printing plate prepared by overlaying a contact screen on an original film, baking it with ultraviolet rays, and developing and etching. In color printing, a yellow plate, a magenta plate, a cyan plate, and a black plate are created from color-separated information of a plate original and overprinted. For example, in FIG. 4, the left column is the yellow plate and the center column is the magenta plate. The plate and the right column show the cyan plate (the black plate is not shown). In FIG. 4, the rhombic cells are shown in white with respect to the copper ground shown in black. Since the three color-separated plates are color-separated even in the same image, cells are formed so that the dot percentages are different at the same position. The rhombus cells up to the shadow portion (substantially square cells are rotated by a required angle) are extracted and arranged in the same arrangement for comparison. In FIG. 4, by changing the direction of the contact screen,
The intersection angle between the diagonally right array of rhombic cells and the doctor contact line direction is 75 degrees for the yellow version and 55 for the magenta version.
Degree, 35 degrees for cyan version, 1 for black version not shown
By setting the angle to 5 degrees, it was attempted to eliminate moire that may occur due to overprinting of four colors from the highlight portion to the halftone portion.

FIG. 5 shows a screen gravure printing plate produced by an electronic engraving machine which engraves the plate surface with a diamond engraving needle. In FIG. 5, the diamond-shaped cells are shown in white with respect to the copper ground shown in black. The rhombic cells produced by the electronic engraving machine are actually slightly horizontal or vertical depending on their size, and are considerably distorted rhombic cells, and the central part of the rhombic cells is the deepest pyramidal shape. As shown in FIG. 5, in the yellow plate, the magenta plate, and the cyan plate that are made by an electronic engraving machine, the intersection angle between the right diagonal arrangement direction and the left diagonal arrangement direction of the rhombic cells is 90 degrees, Moreover, the intersection angle between the right oblique arrangement direction of the rhombic cells and the doctor contact line direction is 45 degrees in all of the yellow plate, the magenta plate, the cyan plate and the black plate (not shown).

[0004]

The halftone gravure printing plate prepared by the film exposure-etching method shown in FIG. 4 still has moire, and further improvement has been demanded. In the yellow plate and the black plate (not shown) where the crossing angle between the doctor contact line direction and the doctor contact line direction is far from 45 degrees, the four sides of the rhombic cell come close to the doctor contact line direction and the direction orthogonal thereto, so the ink transferability However, it was inferior to the magenta plate and the cyan plate in which the crossing angle was not greatly separated from 45 degrees. The halftone gravure printing plate produced by the electronic engraving machine shown in FIG. 5 includes a yellow plate, a magenta plate, a cyan plate, and a black plate (not shown) in which the crossing angle between the diagonally right array direction and the doctor contact line direction is 40 degrees. Since it can only be used at five degrees, there is a drawback that when printing in color, a fairly clear moire is generated from the highlight portion to the halftone portion. In the halftone gravure printing plate created by the electronic engraving machine shown in FIG. 5, the crossing angle between the right oblique array direction of the rhombic cells and the doctor contact line direction is any of the yellow plate, the magenta plate, the cyan plate, and the black plate not shown. Since it is 45 degrees, the transferability of the ink is better than that of the halftone gravure printing plate shown in FIG. 2. However, since the center of the rhombic cell has the deepest pyramid shape, the transferred ink is Since it becomes a heap and does not become smooth, the dispersibility of the ink is poor, which is a cause of lowering the gradation level.

According to the present invention, the dispersibility of ink is high from the highlight portion to the shadow portion when color printing is carried out by overprinting a plate of three-color or four-color separation, and the occurrence of moire can be prevented, and the highlight portion can be avoided. It is an object of the present invention to provide a halftone gravure printing plate having good ink transferability and good gradation of gradation.

[0006]

According to the present invention, the crossing angle between the right diagonal arrangement direction and the left diagonal arrangement direction of cells from the highlight portion to the shadow portion is 90 degrees, and the right diagonal arrangement direction and the doctor contact. In the net gravure printing plate where the angle of intersection with the line direction is smaller or larger than the required angle of 45 degrees,
Dot percentage is about 31% by laser exposure scanning
The smaller cells are diamond-shaped cells that are elongated in the direction orthogonal to the doctor contact line direction and have a dot percentage of about 56%, and a dot percentage of about 31% to about 56%. The small cell has the same shape as the cell having the outer peripheral contour of about 56% and a hollow hollow circle, and one diagonal direction of the cell having the outer periphery of about 31% to about 56% is the doctor contact line direction. The dot percentage is approximately 56%.
A halftone cell having a larger area is a rhombic cell, and one side of the cell is aligned with the right oblique arrangement direction of the cell.

[0007]

EXAMPLE An example of the halftone gravure printing plate of the present invention will be described with reference to FIG. The net gravure printing plate of this example is
Similar to the halftone gravure printing plates of FIGS. 4 and 5, all of the yellow plate, the magenta plate, the cyan plate, and the black plate (not shown) are arranged diagonally to the right and left of the rhombic cells from the highlight portion to the shadow portion. The intersection angle with the array direction is 90 degrees. The screen gravure printing plate of this example is shown in FIG.
As with the mesh gravure printing plate of, the intersection angle between the cell diagonally right direction and the doctor contact line direction is 75% for the yellow plate.
The magenta plate is 55 °, the cyan plate is 35 °, and the black plate (not shown) is 15 ° so that the same moire eliminating effect as that of the halftone gravure printing plate of FIG. 4 can be obtained.

In the halftone gravure printing plate of this embodiment, the dot percentage is 2% to 2% for any of the yellow plate, the magenta plate, the cyan plate and the black plate, as shown in FIGS. 27% of the cells are formed in the shape of an elongated hole with a long rounded corner in the direction orthogonal to the doctor contact line direction, and the length and width of the elongated hole gradually increase as the dot percentage increases. . There is a limit of less than about 31% for forming the long-hole-shaped cell.

The basis for the numerical value calculation of less than about 31% is
As shown in FIG. 3A, the dot percentage is 30%.
In order to avoid the arrangement of the cells adjacent to each other in the cell of the yellow plate in the case of forming the oblong hole, the number of screen lines is as shown in FIG. 3 (b). Screen line width 1 per 175 lines / inch
The dot percentage of a ring-shaped diamond-shaped cell in which a groove width of the cell is about 15 microns and a diagonal diameter dimension is inscribed in a 45-micron square is 31%. It is based on the two points that the line width dimension of the screen between is about 15 microns.

However, in the case where the cells are elongated holes (including ellipses) which are shorter and wider than the elongated cells having a dot percentage of 30% shown in FIG. 3A, Even if the dot percentage is 35%, the cells adjacent to each other do not overlap each other, and the screen line width dimension between the cells can be 10 to 15 μm. In addition, the groove width of the cell is smaller when the cell is an annular diamond-shaped cell having a larger inner peripheral contour and a dot percentage of 27% than the elongated hole-shaped cell having a dot percentage of 31% shown in FIG. 3B. However, it is possible to avoid the arrangement in which the cells adjacent to each other are overlapped with each other, as in the case of the slot-shaped cells having the dot percentage of 31%. Therefore, in the present specification, "less than about 31%" which is the basis of the numerical value calculation of less than about 31% is
It shall be a numerical value meaning 31% plus or minus a few percent.

As described above, when the cell has an elongated hole shape elongated in the direction orthogonal to the doctor contact line direction, the overlapping of the yellow plate, the magenta plate, the cyan plate and the black plate becomes small, and the mesh shown in FIG. The effect of eliminating moire that is greater than that of the gravure printing plate can be obtained. Also, if the cell is in the shape of an elongated hole that is long in the direction orthogonal to the doctor contact line direction, the distance from the screen line to the screen where the doctor contacts is small,
When the ink is scraped off with a doctor, the ink enters the cells well, so that the transferability of the ink is good and the gradation degree of light and shade is improved.

Further, the halftone gravure printing plate of this embodiment has a dot percentage of about 31% to about 5 for any of the yellow plate, the magenta plate, the cyan plate and the black plate.
Cells smaller than 6% are formed into diamond-shaped annular cells, cells with a dot percentage of about 56% are formed into diamond cells, and further cells with a dot percent of about 31% to about 56% are formed. Two diagonal directions are formed in a rhombic ring cell or a rhombic cell which is a doctor contact line direction and a direction orthogonal to the doctor contact line direction, and furthermore, a cell having a dot percentage of less than about 31% to about 56% has a peripheral contour of about 31%. The dot percentage is gradually increased by expanding the groove width inward with the cell having the same shape of 56%.

For cells having a dot percentage of about 31% to about 56%, the two diagonal directions are aligned with the doctor contact line direction and the direction orthogonal thereto so that it is parallel to the doctor contact line direction of the contour side of the cell. Doing not, because of the inclination of 45 ° with respect to the doctor contact line direction, when scraping the ink with the doctor, the ink will enter the cell well and This is because the transferability of the ink from the ink to the paper is good and the gradation degree of light and shade is improved.

A cell having a dot percentage of less than about 31% to about 56% is formed in a rhombic annular cell, and a cell having a dot percentage of about 56% is formed in a rhombic cell, as shown in FIG. 3 (c). As shown in, the number of screen lines is 17
The dot percentage of an annular diamond-shaped cell with a diagonal corner diameter inscribed in a square with a screen line width of 145 microns per 5 cells / inch is about 56%. As shown in FIG. For cells, based on the screen line width dimension between the ring-shaped diamond cells and the cells being about 15 microns, for cells with a dot percentage of less than about 31% to about 56%, the outer contour is the same shape. This is because the dot percentage is gradually increased by gradually expanding the groove width inward. In other words, the reason why the diamond-shaped annular cell in which the hollow portion (island-like non-cell portion) is gradually reduced is that it is approximately 56% when the hollow portion is eliminated. ,
The outer peripheral contour is adapted to the size of the rhombic cell which is about 56%.

The dot percentage of a circular rhombic cell with a rounded corner inscribed in a square having a screen line width of 145 microns per 175 screen lines / inch and a diagonal diameter dimension is about 56%. At this time, the line width of the screen between the cells adjacent to each other becomes 15 μm (see FIG. 3B). If you increase the roundness of the corners, the dot percentage will decrease by about 2%, while on the other hand, the screen line width between cells will be about 8 microns.
The screen line width between adjacent cells should be 1
The dot percentage of the ring-shaped diamond-shaped cells when the size of the cell protrudes from the 45-micron square is 3% rather than 56%.
5% larger. Therefore, it is assumed in the present specification that the basis of the above-mentioned numerical value calculation of about 56% is a numerical value which means 56% plus or minus several percent.

For cells having a dot percentage of less than about 31% to about 56%, not a rhombic cell but a ring-shaped rhombus in which the outer peripheral contour has the same shape and the groove width gradually expands inward is as follows. Compared to the case where diamond cells with the same dot percentage are used (compared to the diamond cells with corresponding dot percentages in FIGS. 4 and 5), the degree of ink overlap is smaller, and a greater moire elimination effect is obtained. This is because the dispersibility of the ink is large and the density looks high even with the same amount of ink.

A cell having a dot percentage of more than about 56% is a rhombic cell, and one side of the cell coincides with the right diagonal arrangement direction of the cell. That is, as can be seen from FIG. 1, the right diagonal arrangement angle of the cell with respect to the doctor contact line is
75 ° for the yellow version, 5 for the magenta version
The angle is 5 °, 35 ° for the cyan plate, and 15 ° for the black plate, and the tilt angle of the cell also matches the right oblique array angle of the cell. Therefore, the dot percentage is about 56
About the cell exceeding%, it is the same as the halftone gravure printing plate shown in FIG. The reason for doing this is as follows. That is, about 56% is required to eliminate moire.
For cells in the range beyond, one diagonal direction is
It is preferable that the line is formed so as to be orthogonal to the doctor contact line direction, but if this is done, the screen line will be cut off by etching. Approximately 56
For cells in the range exceeding%, one diagonal direction of the cell is not orthogonal to the doctor contact line direction, and as in the case of FIG. 4, the four sides of the cell are diagonally arranged to the right of the cell and diagonally to the left. It is designed to match the arrangement direction.

In the halftone gravure printing plate of this embodiment, the cell shape of the most shadow portion is a scale-like arrangement in which the screen lines bent at substantially right angles are arranged in all of the yellow plate, the magenta plate, the cyan plate and the black plate. At the intersection of the screen line, three cells communicate with each other with a width equal to or smaller than the width of the screen line.

As a specific example of the method for producing this net gravure printing plate, the plate surface formed by ballad copper plating of about 100 microns is grindstone-polished or buff-polished and surface-activated, and then an argon / neon gas laser beam is produced. A photosensitive resin film having high sensitivity characteristics that can be cured by a weak laser beam such as mu is applied and formed so as to have a thickness of 5 to 8 microns, and a film for preventing oxidation of the photosensitive resin film is overcoated, Then, the photosensitive resin film is subjected to main scanning with the laser beam in a direction orthogonal to the doctor plate contact line, and sub-scanning is performed so that adjacent irradiated lines on the plate surface of the laser beam overlap and deviate from each other, and print information By blinking and irradiating the corresponding laser beam, the negative printing information is written on the photosensitive resin film, and then the development is performed. After the unexposed part of the photosensitive resin film is dissolved, the resist is heated and hardened and then etched to engrave positive print information on the plate surface in halftone dots, and the resist is peeled off and chrome plating is applied to give printing durability. .

The halftone gravure printing plate of the present invention includes not only roll printing plates but also planographic printing plates. Further, the present invention is not limited to the plate making method shown in the above embodiment, that is, the method of forming a resist image by laser exposure / development and the subsequent etching, such as an epoxy resin containing magnetic powder on the roll surface. It may be a net gravure printing plate which is formed of a hard plastic film and in which cells are directly engraved with a high-strength laser such as a YAG laser. Further, according to the present invention, the intersection angle between the right oblique arrangement direction of the rhombic cells from the highlight part to the shadow part and the doctor contact line direction is, for example, 75 ° for the magenta plate, 55 ° for the cyan plate, and 35 ° for the black plate, The yellow version may be 15 degrees, or the magenta version may be 65 degrees, the cyan version may be 45 degrees, the black version may be 25 degrees,
And the yellow version may be 5 degrees. In the description of the above-mentioned example, the intersection angle between the right diagonal arrangement direction and the left diagonal arrangement direction of the cells from the highlight portion to the shadow portion is 90 degrees,
The halftone gravure printing plate was described in which the crossing angle between the right diagonal arrangement direction and the doctor contact line direction was inclined at a required angle smaller or larger than 45 degrees. The intersection angle between the right diagonal arrangement direction and the left diagonal arrangement direction of the cells from the highlight portion to the shadow portion is 90 degrees, and the intersection angle between the right diagonal arrangement direction and the doctor contact line direction is 45 degrees. With respect to the halftone gravure printing plate, the cells in which the dot percentage is in the range of about 31% to about 56% and the cells in which the dot percentage exceeds about 56% are the same as in the case of FIG.

[0021]

As described above, according to the halftone gravure printing plate of the present invention, when color printing is performed by overprinting a plate in which three colors or four colors are separated, the colors from the highlight part to the halftone part are printed. As a result of the more evenly distributed overlapping of ink, moire does not occur and the density looks large even with the same amount of ink, and when the ink is scraped off with a doctor, the ink is better in the cells. Since it penetrates, it has an effect that the transferability of the ink is improved and the gradation degree of light and shade is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a screen gravure printing plate of the present invention.

FIG. 2 is a design drawing of a cell showing the halftone gravure printing plate of the present invention.

FIG. 3 is a cell array examination diagram showing the halftone gravure printing plate of the present invention.

FIG. 4 is a view showing a conventional halftone gravure printing plate prepared by superposing a contact screen on an original film, baking it with ultraviolet rays, developing and etching.

FIG. 5 is a diagram showing a screen gravure printing plate created by an electronic engraving machine that engraves a plate surface with a diamond engraving needle.

Claims (1)

[Claims] 1. The crossing angle between the right diagonal arrangement direction and the left diagonal arrangement direction of cells from the highlight portion to the shadow portion is 90 degrees, and the crossing angle between the right diagonal arrangement direction and the doctor contact line direction is four. In a net gravure printing plate with a required angle smaller or greater than 15 degrees, by laser exposure scanning,
A cell having a dot percentage of less than about 31% is a rhombic cell having a long shape in a direction orthogonal to the doctor contact line direction and a cell having a dot percentage of about 56%, and a dot percentage of about 31%. From about 56% to about 31% are cells having the same shape as the cells having the outer peripheral contour of about 56% and hollowed-out annular shape,
% To about 56%, and one diagonal direction of the cell is formed so as to be orthogonal to the doctor contact line direction,
A halftone gravure printing plate characterized in that cells having a dot percentage of more than about 56% are rhombic cells, and one side of the cells coincides with a right oblique arrangement direction of the cells.