JP3099505B2 - Screenless prepress printing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screenless plate-making printing method for obtaining a screenless printed matter.

[0002]

2. Description of the Related Art Conventional plate-making of screenless printed matter (printed matter having a regular screenless printed image for reproducing gradation of printing density) is performed by converting a continuous-tone color separation film image into a lithographic plate. It is brought into close contact with a printing plate (a metal lithographic printing plate such as aluminum coated with a photosensitive resin in advance and having fine-grained irregularities on its surface, called a PS plate) and appropriately exposed to light (exposure time). After the lithographic printing plate has been exposed to ultraviolet light, a screenless printing plate is prepared by subjecting the lithographic printing plate to a developing and rinsing process. I was printing.

[0003] The image portion held on the fine-grained uneven surface of the screenless printing plate after the developing water washing treatment in the plate making is one of the fine-grained uneven portions on the printing plate surface of the PS plate. The photosensitive resin (positive-positive exposure) layer held in the concave portion after the exposure and development is constituted by a difference in area and layer thickness, and the image portion pattern has a grain shape having a large and small planar appearance.

[0004] The reproduction of the print gradation of the image portion held by exposure and development on the screenless printing plate is performed by the exposure amount of ultraviolet light corresponding to the image of the continuous gradation color separation film and the grain-shaped surface recess. The rough V-shaped cross-section of the printing plate secures an irregular grained large and small image portion of the printing plate, and the grained surface roughness of the printing plate surface and the irregular large and small sand The screen-like printing plate having no halftone dots and the gradation of light and shade of the printed matter are reproduced by the eye-shaped image portion.

[0005]

By the way, the above-mentioned conventional screenless plate making method uses continuous tone (continuous stone) whose density is adjusted particularly for screenless plate making.
This is a method of performing exposure plate-making processing by using the color separation film in close contact with the PS plate surface, and requires much labor and time for exposure adjustment suitable for screenless plate-making in the exposure plate-making processing.

According to the present invention, a screenless printing plate can be easily made using a normal color separation halftone positive film in which halftones are reproduced by halftone dots (dot patterns). In addition to obtaining printed products, in the present invention, in particular, in the image of the color separation screen positive film used for plate making, a line drawing image of each color (solid line drawing,
In a case where a solid line drawing or a line drawing image having shades of gray is included, it is an object to make it possible to print with less noticeable color misregistration at the time of each color overprint in the outer peripheral contour portion of the line drawing image.

[0007]

Means for Solving the Problems A first invention of the present invention is:
A color separation halftone positive image that is color-separated from the original image and is reproduced with halftones by halftone dots, and a solid or plain net line drawing positive image is created.Each color separation halftone positive image has a transparent film or light diffusion effect. Image exposure to a positive type lithographic printing plate through a translucent film having, the line drawing positive image is image exposed to a positive type lithographic printing plate, and the imagewise exposed lithographic printing plate is subjected to development processing for each color. After making a screenless printing plate with a separation screen positive image and a normal printing plate with a line drawing positive image, the image portion of the color separation screen positive image equivalent part is printed on a predetermined printing material using a screenless printing plate. Subsequently, an image portion corresponding to a line drawing positive image is printed using a normal printing plate.

[0008] The present invention is also characterized in that a screenless 0.01 to 0.2 mm thick diffusion sheet is used as the translucent film having the light diffusion effect used in the first invention. This is a prepress printing method.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first invention of the screenless plate making method of the present invention will be described in detail below. Create a separation net positive image. FIG. 1 is for cyan printing or magenta printing,
Or a color separation screen positive image 1 (color separation screen positive film or C of a scanner electronic plate making apparatus for producing any printing plate for yellow printing or black printing).
The positive image 1 includes a gray-scale tone reproduction image area 2 (gradation image area) in which the gray scale is reproduced by a halftone dot (dot pattern), and a line drawing area 3. ing.

The line drawing area 3 may be provided with a halftone image reproduced by a dot pattern (halftone dot) such as dot gradation as appropriate, but the screenless plate making method according to the first invention of the present invention. In the above, the screenless plate making is not performed on the line drawing area 3 and the halftone image included in the area 3.

First, the color separation screen positive image film 1 shown in FIG.
Only the gradation image area 2 of each of the cyan, magenta, yellow, and black color separation screen positive image films is masked to provide a light-shielding area 5 as shown in FIG. A line drawing negative image 4 (film) is created for each color having the third negative image 3a. Subsequently, the masking film 4 is photo-inverted and the negative image 3a in the line drawing area 3 is inverted to a positive image 3b to create a line drawing positive image 6 (film). (See FIG. 2 (b))

Next, as shown in FIG. 3, the presensitized lithographic printing plate 13 (hereinafter, referred to as PS plate) is opposed to and separated from the lithographic printing plate 13 (hereinafter, referred to as a PS plate) via a light-transmissive spacer film 12. The color separation screen positive film 1 of one color of each color separation screen positive film of each color (cyan, magenta, yellow, and black printing colors) having the color separation screen positive image 1b From the film 1 side, on a printing plate 13 using a carbon arc lamp for printing plate baking, a metal halide lamp, an ultra-high pressure mercury lamp, etc.
Irradiation with ultraviolet light L (irradiation time is, for example, 30 seconds to 300
Set to any of the range of seconds) and each color separation halftone positive image 1
By subjecting the printing plate 3 to image exposure and then developing the printing plate 3, a planographic printing plate for screenless printing is obtained for each printing color of cyan, magenta, yellow, and black. In addition, the color separation net positive film 1 may have its image film surface directed to either the printing plate 13 side or the ultraviolet light source side.
It is desirable to turn to the 3 side.

In the lithographic printing plate 13 (PS plate), a positive type photosensitive resin layer 15 is applied to the surface of a printing plate substrate 14 made of metal such as aluminum on which fine grain-like irregularities are formed. Each of the concave portions 14a of the fine grain-like irregularities has an inclined surface having a substantially V-shaped cross section as shown in FIG.

Normally, when the color separation halftone positive film 1 is brought into close contact with the PS plate 13 and exposed, the halftone positive image 1
b is formed on the PS plate 13 as a halftone image as it is. In the present invention, as shown in FIG.
b having a light diffusion effect between the color separation net positive film 1 having the b and the PS plate 13.
m, preferably a translucent film (a diffusion sheet or a mat film) having a thickness of 0.05 mm to 0.3 mm, or a spacer film 12 of a translucent film using a transparent film having a thickness of 0.01 mm to 1.0 mm. By exposing through, or when the spacer film 12 is a translucent film (matte film),
By exposing the upper side of the color separation net positive film 1 through the spacer film 12 as necessary,
The original shape of each halftone dot of the halftone image exposed on the plate 13 is blurred, and the change in the halftone dot area ratio for expressing the gradation of the halftone image is caused by the change in the exposure amount of the PS plate 13 to the photosensitive material 15. The change in the amount of exposure is converted into a change in the thickness of the photosensitive material, and gradation expression is performed.

This is because the spacer film 12 is exposed at the time of exposure.
When the exposure amount corresponding to the dot area ratio reaches the positive PS plate 13, the light is exposed according to the dot percentage of the halftone positive image 1 b. When the subsequent PS plate 13 is developed, the film thickness remaining and retained on the surface of the PS plate 13 (lithographic printing plate) changes. As the film thickness decreases, the V-shape of the concave portion 14a on the surface of the PS plate 13 decreases. The area of the image portion 16 is reduced by the inclined surface, and the area of the image portion 16 is increased as the film thickness approaches the initial film thickness.

Further, according to the present invention, the halftone positive image 1b is directly exposed on the lithographic printing plate 13 via the spacer film 12 by the projection exposure method without using the color separation halftone positive film 1. That is to say.

FIG. 4 shows the above-mentioned halftone positive image 1 having a gray scale.
b is exposed on a positive type lithographic printing plate 13 by image exposure (in FIG. 4, the magnitude of the exposure is indicated by the number of ultraviolet L arrows) and the graininess of the lithographic printing plate 13 V-shaped recess 14a on the uneven surface of
FIG. 3 schematically illustrates reproduction of light and shade gradation by a screenless plate making image portion expressed on the surface of a lithographic printing plate 13 expressed after a development process.

In FIG. 4, zero or slight ultraviolet light L
The area of the lithographic printing plate 13 exposed by the exposure amount of
The unexposed portion 16-1 of the unexposed portion where the photosensitive resin layer 15 is not exposed to light, having a continuous or slightly divided large area without division of the photosensitive resin layer 15, The shadow tone area S1 which retains the film thickness of the fifteen main bodies is represented.

The area of the lithographic printing plate 13 that is slightly exposed to light by the slight amount of exposure to the ultraviolet light L is applied to the photosensitive resin layer 1.
5 slightly decomposes, and after development, the photosensitive material on the upper side is removed, and the image portion 16 of the minute exposure portion in a state where the film thickness is reduced.
−2, which represents a middle tone area S2 having a large area and being close to a shadow tone.

In the area of the lithographic printing plate 13 which has been exposed to the medium amount of ultraviolet light L, the upper photosensitive material is removed by development, and the image area 16 of the intermediate exposure portion having a reduced thickness is developed. -3, a middle tone area S2 having a medium area and close to a highlight tone.

In the area of the lithographic printing plate 13 which has been exposed by the large amount of exposure to the ultraviolet light L, the upper photosensitive material has been largely removed by development, and the image area 16 of the exposed portion having a reduced film thickness has been removed. -4, which is a small area highlight tone area S
3 is represented.

The area of the lithographic printing plate 13 which has been exposed by the stronger exposure amount of the ultraviolet light L is a non-image area 17 of an exposed portion from which the photosensitive material has been completely removed by development.
A highlight tone area S3 without an image portion is represented.

The screenless plate-making and printing method of the present invention comprises:
Lithographic printing plate 1 in which the gradation is reproduced based on the above principle
And a planographic printing plate 13 presensitized with a positive type photosensitive resin (photosensitive material).
(Hereinafter referred to as PS plate), and a spacer 12 (0.2 m
m), and a cyan color separation screen positive film 1 having a color separation screen positive image 1b for cyan printing plate exposure plate making made by red filter spectroscopy with shading is formed. And irradiating ultraviolet light L onto the lithographic printing plate 13 from the color separation screen positive film 1 side to image-expose the cyan separation screen positive image 1b,
Thereafter, the lithographic printing plate 13 is developed to obtain a screenless printing plate for cyan printing.

Subsequently, on another lithographic printing plate 13 (hereinafter, referred to as PS plate), which has also been presensitized, the light and shade are separated by a spacer 12 (0.2 mm light-transmitting mat film). A magenta color separation mesh positive film 1 having a color separation mesh positive image 1b for magenta printing plate exposure plate making formed by gradation green filter spectroscopy is arranged, and from the color separation mesh positive film 1 side, lithographic printing The plate 13 is irradiated with ultraviolet light L to expose the magenta color separation halftone positive image 1b to an image.
Is developed to obtain a lithographic printing plate for screenless printing of a magenta printing color.

Subsequently, on another planographic printing plate 13 (hereinafter referred to as PS plate), which has also been presensitized, a light and shade is formed by a spacer 12 (0.2 mm translucent mat film). A yellow color separation net positive film 1 having a color separation net positive image 1b for yellow printing plate exposure plate making formed by gradation blue filter spectroscopy is arranged, and from the color separation net positive film 1 side, a planographic printing The plate 13 is irradiated with ultraviolet light L to expose the yellow color separation halftone positive image 1b to an image, and then the planographic printing plate 13 is developed to obtain a planographic printing plate for screenless printing of yellow printing color. Things.

Subsequently, on another lithographic printing plate 13 (hereinafter referred to as PS plate), which has also been presensitized, the lithographic printing plate 13 is spaced apart and opposed via a spacer 12 (0.2 mm light-transmissive mat film). A black color separation screen positive film 1 having a color separation screen positive image 1b for black printing plate exposure plate making formed by gradation yellow filter spectroscopy is arranged, and the lithographic printing The plate 13 is irradiated with ultraviolet light L to image-expose the black color separation net positive image 1b, and then the planographic printing plate 13 is exposed.
Is developed to obtain a lithographic printing plate for screenless printing in black printing color.

Each of the color separation halftone positive images 1b is obtained by subjecting a known color separation (color separation) process, a halftone dot separation (dot separation) process, and appropriate platemaking conditions to a predetermined color original by an ordinary plate making camera. An image may be formed by using an electronic plate making device (color scanner plate making device).

Cyan (Cya) produced as described above
n), magenta (Magenta), yellow (Yel)
low-color and black (Black) using a screenless printing plate 13 of each color and a normal lithographic printing ink or a lithographic printing ink appropriately diluted with a medium, using a multi-color lithographic printing press (or a monochromatic or two-color printing) By printing on a printing medium (printing paper, synthetic paper, synthetic resin film, etc.) by a printing machine, as shown in FIG.
A screenless print image area 8 in which ink adheres to a printing medium in accordance with the area of each image portion S1, S2, S3, S4 on each color printing plate 13 to reproduce the gradation of print density; A printed material A is obtained in which the line drawing printing area 9a that has been screenlessly made is printed at the same time as the screenless printing image area 8 is made.

Then, using the above-described line drawing positive image 6 (line drawing positive image film, see FIG. 2B), lithographic printing for printing the line drawing area 3 by a normal lithographic printing plate making method. This is to make a plate.

First, the line drawing positive image film 6 is closely adhered onto the presensitized lithographic printing plate 13 and the lithographic printing plate 1 is placed from the positive image film 6 side.
3 is irradiated with ultraviolet light L to image-expose the positive image 3b in the line drawing area 3, and the lithographic printing plate 13 is subjected to development processing, whereby each color (any of cyan, magenta, yellow, and black) is developed. This is to obtain a normal lithographic printing plate for line drawing printing for printing the line drawing region 3 of FIG.

Using a normal lithographic printing plate 13 provided with a line drawing positive image 3b for printing the line drawing area 3 and a normal lithographic printing ink, a multicolor lithographic printing machine (or a single-color to two-color printing machine) Machine, etc.), on a screenless line drawing printing area 9a printed simultaneously with the screenless printing image area 8 of the printed matter A by any one of the flat pressure type, the circular pressure type, and the rotary printing type. 9 is printed by overprinting, so that the screenless print image area 8 and the line print area 9 shown in FIG.
Is obtained.

In the first embodiment of the present invention, the image of the line drawing area 3 of the color separation halftone positive image 1 shown in FIG. 6A is cut out as shown in FIG. It is possible to make a plate of the color separation halftone positive image 10 having the cutout area 2a, and to make a plateless screenless printing plate for each color printing as described above using the color separation halftone positive image 10, The printed material A can be printed using a printing plate for screenless printing image area printing made using the halftone positive image 10 and the printing plate for printing the image area area.

A second invention of the screenless plate-making printing method according to the present invention relates to a positive image of each color separation halftone which is color-separated from an original image and a halftone is reproduced by a halftone dot, and a line image positive image of a solid or plain net. Each of the color separation screen positive images is image-exposed to a positive type lithographic printing plate via a transparent film or a translucent film having a light diffusion effect, and the line drawing positive image is image-exposed to a positive type lithographic printing plate. Then, after the imagewise exposed lithographic printing plate is subjected to development processing, a screenless printing plate with each color separation halftone positive image, and a normal printing plate with a line drawing positive image, and
A screenless plate making in which an image portion corresponding to a color separation halftone positive image is printed on a predetermined printing medium using a screenless printing plate, and then an image portion corresponding to a line drawing positive image is printed using a normal printing plate. In the printing method, when making a screenless printing plate by imagewise exposing a lithographic printing plate using each color separation halftone positive image, imagewise exposing at a large exposure amount to make a screenless printing plate for shadow tone. To make a screenless printing plate for middle tone by image exposure at medium exposure, plate making a screenless printing plate for highlight tone by image exposure at low exposure, the above normal printing plate A screenless printing plate characterized by printing on a printing medium using a lithographic printing ink diluted with an appropriate dilution ratio on the screenless printing plate using a normal lithographic printing ink. A plate printing method.

[0034] The present invention also provides a screenless screen characterized in that a diffusion sheet having a thickness of 0.01 mm to 0.2 mm is used for the translucent film having the light diffusion effect used in the first invention. This is a plate-making printing method, which will be described in detail below according to examples.

From a predetermined color original, a known color separation step and halftone separation step, or a cyan color separation halftone positive image for cyan printing plate exposure plate making formed by red filter spectroscopy having a gradation of gradation by an electronic plate making apparatus. A magenta color separation net positive film for magenta printing plate exposure plate making formed by shading green filter spectrum,
Positive film for yellow printing plate exposure plate making made by blue filter spectrum with light and shade gradation, and black color separation net for black plate printing exposure plate making made with yellow filter spectrum with light and shade gradation Create a positive film.

FIG. 1 shows a color separation screen positive image 1 for producing a printing plate for cyan printing, magenta printing, yellow printing, or black printing.
(One frame of a CRT image of a color separation screen positive film or a scanner electronic plate making apparatus).
Has a gradation image reproduction area 2 (gradation image area) in which gradation is reproduced by halftone dots (dot patterns), and a line drawing area 3.

First, the color separation screen positive image film 1 shown in FIG.
Only the gradation image area 2 of each of the cyan, magenta, yellow, and black color separation screen positive image films is masked to provide a light-shielding area 5 as shown in FIG. A masking film 4 for each color with the negative image 3a is prepared.

Subsequently, the masking film 4 is photograph-reversed, and the negative image 3a in the line drawing area 3 is reversed to a positive image 3b to form a line drawing positive image 6. (See FIG. 2 (b))

Next, as shown in FIG. 3, each of the color separation screen positive image film 1 of the cyan color separation screen positive film, the magenta color separation screen positive film, the yellow color separation screen positive film, and the black color separation screen positive film is used. Is used to expose each lithographic printing plate 13 through a spacer 12 in an imagewise manner.
The screenless stencil printing method of the second invention will be described with reference to the embodiment of FIGS.

First, as shown in FIG. 7A, a presensitized positive-type planographic printing plate 13 is placed on
Via a spacer film 12 (a diffusion sheet or a mat film) having a light diffusion effect, a cyan color separation halftone positive film 1C (a halftone dot image 1b-s forming a shadow tone region and a halftone forming a middle tone region) (Having a dot image 1b-m and a halftone image 1b-h constituting a highlight tone area), and irradiating ultraviolet rays L1 with a large exposure amount from the upper side to perform development processing. As a result, as shown in FIG. 7B, the halftone images 1b-s constituting the shadow tone area are opened between each other and the halftone images 1b-m constituting the middle tone area are respectively opened. The image portion 16 having a (void) and the image portion 1 corresponding to the halftone image 1b-h constituting the highlight tone area
The lithographic printing plate 13 for cyan printing (FIG. 7B) holding the image portion 16 for shadow tone reproduction with good reproducibility of a so-called shadow tone region from which 6 has been removed is made.

In this case, the positive film 1C and the printing plate 13 may be brought into close contact with each other with the spacer 12 interposed therebetween, or the positive film 1C, the spacer 12 and the printing plate 13 may be appropriately separated from each other (for example, 0.01
mm to about 1.0 mm).

As shown in FIG. 7A, the light image of the ultraviolet rays L1 transmitted through the non-image area 1a of the positive film 1C is scattered in four directions by the spacers 12 and the printing plate 1
Since the photosensitive material 15 reaches the photosensitive material 15, the light irradiation area on the photosensitive material 15 is larger than the non-image area 1a. Therefore, in the lithographic printing plate 13 (cyan plate) obtained by the development processing, as shown in FIG. 7B, the halftone images 1b-s of the shadow tones are opened between each other, and the Thus, a lithographic printing plate 3 (FIG. 7 (b)) for reproducing shadow tones, in which the subtle shades of gray are reproduced.

Next, FIG. 8A, the same cyan color as above is placed on another presensitized positive type lithographic printing plate 13 via a spacer 12 (mat film) having a light diffusion effect. Disassembling net positive film 1C is arranged and irradiated with ultraviolet light L2 at a moderate exposure amount from above,
Develop. As a result, as shown in FIG. 8B, the halftone image 1b-
s and a halftone image 1b
-M and a halftone image 1b
The planographic printing plate 13 for cyan printing holding the image area 16 for the middle tone reproduction having the same gradation reproduction of the shade as the positive film 1C over the highlight tone area constituted by -h (FIG. 8B )) Is made.

Subsequently, in FIG. 9A, the same cyan color as above is placed on another presensitized positive-type planographic printing plate 13 via a spacer 12 (mat film) having a light diffusion effect. A decomposition net positive film 1C is disposed, and ultraviolet light L3 with a small exposure amount is irradiated from above to develop.

As a result, as shown in FIG.
The halftone image 1b-
s and a halftone image 1b
-M and a halftone image 1b
The planographic printing plate 13 for cyan printing, which has an image portion 16 for reproducing highlight tones having substantially the same gradation reproducibility as the positive film 1C over the highlight tone region constituted by -h (FIG. 9). (B)) is made. In this way, three screenless printing plates 13 each for shadow tone reproduction, middle tone reproduction, and highlight tone reproduction for cyan printing are produced.

In the same manner as the above-described three printing plates for cyan printing, the printing plates for magenta, yellow, and black were respectively formed, and shadow tone reproduction for magenta printing, middle For tone reproduction,
Three screenless printing plates 13 each for highlight tone reproduction, three screenless printing plates 13 each for shadow tone reproduction, middle tone reproduction, and highlight tone reproduction for yellow color printing, and Three screenless printing plates 13 each for shadow tone reproduction, middle tone reproduction, and highlight tone reproduction for black color printing are prepared. In addition, about the screenless printing plate for black color printing, the plate-making only of the printing plate for middle tone reproduction may be sufficient.

The printing method in the screenless plate-making printing method of the second invention will be described in detail below with reference to Examples. Each color (cyan, magenta, and magenta) obtained by the screenless plate-making method of the second invention will be described. Screenless printing plate 1 for each of yellow, black, shadow tones, middle tones and highlight tones
3 (lithographic printing plate) and a lithographic printing ink diluted at an appropriate dilution ratio to print on a printing medium (printing paper, synthetic paper, synthetic resin sheet, etc.). explain.

Four lithographic printing plates for cyan, magenta, yellow, and black middle tone printing, four lithographic printing plates for each color shadow tone printing, and four lithographic printing plates for each color highlight tone printing A total of 12 lithographic printing plates for shadow tone printing, middle tone printing, and highlight tone printing using a lithographic printing plate are printed on a lithographic printing machine (flat pressure type, circular pressure type, rotary type). ) Is mounted on a plate mounting part such as a plate cylinder, and lithographic printing ink diluted with a medium is supplied, and printing paper is printed by a normal lithographic printing method (using a dampening solution or no dampening solution). Screenless printing is performed on a printing medium such as a synthetic resin film or synthetic paper to obtain a screenless printed material A as shown in FIG.

In this case, it is not always necessary to use all 12 lithographic printing plates for reproducing gradations of light and shade in the shadow tone printing area, the middle tone printing area, and the highlight tone printing area. It is possible to make appropriate changes while visually monitoring the density reproduction state of the printed matter to be printed.

First, for the printing plate for the middle tone, for example, a diluting ink or a lithographic printing ink having a mixing ratio of 40% to 60% of a lithographic printing ink and 40% to 60% of a medium for diluting an ink concentration is used. Print. When printing using the lithographic printing plate for tone reproduction adjustment,
The printing plate for each color shadow tone is printed using, for example, 90% to less than 100% of a lithographic printing ink.

The printing plates for each color highlight tone include:
For example, printing is performed using a diluted ink adjusted to a blending ratio of 5% to 20% of lithographic printing ink and 95% to 80% of an ink concentration diluting medium.

As described above, Cyan,
Magenta, Yellow
w), using a screenless printing plate 13 of each color of black and a lithographic printing ink appropriately diluted with a medium, using a multicolor lithographic printing machine (or a monochromatic or two-color printing machine or the like). (Printing paper, synthetic paper, synthetic resin film, etc.), as shown in FIG. 5, each image portion S1, S2,
The ink adheres to the printing medium according to the area of S3 and S4,
A printed matter A is obtained in which the screenless print image area 8 in which the gradation of the print density is reproduced and the line drawing print area 9a in which the screenless platemaking is performed simultaneously with the platemaking of the screenless print image area 8 are obtained.

Subsequently, in the same manner as in the first invention, using the line drawing positive image 6 of each color described above (a line drawing positive image film, see FIG. 2B), in a normal planographic printing plate making method. After making a normal lithographic printing plate 13 for printing the line drawing area 3, the lithographic printing plate 13 and a multicolor lithographic printing machine (or a single-color to two-color printing machine or the like) using a normal lithographic printing ink are used. By printing the line drawing printing area 9 on the screenless line drawing printing area 9a printed simultaneously with the screenless printing image area 8 of the printed matter A, the screenless printing image area 8 shown in FIG. A printed matter A having the printed image 7 in the line drawing printing area 9 is obtained.

In the second embodiment of the present invention, the image of the line drawing area 3 of the color separation halftone positive image 1 shown in FIG. 6A is cut out as shown in FIG. It is possible to make a plate of the color separation halftone positive image 10 having the cutout area 2a, and to make a plateless screenless printing plate for each color printing as described above using the color separation halftone positive image 10, The printed material A can be printed using a printing plate for screenless printing image area printing made using the halftone positive image 10 and the printing plate for printing the image area area.

Further, in the screenless plate-making printing method of the present invention, image exposure and development processing (surface conditioning processing, gumming processing,
Alternatively, the lithographic printing plate 13 may be subjected to a burning process by appropriately heating the lithographic printing plate 13 to about 200 ° C. to 270 ° C. It is possible to increase the holding power.

[0056]

According to the screenless plate-making printing method of the present invention, each color separation halftone positive image is image-exposed to a positive-type lithographic printing plate via a translucent film spacer film having a transparent or light diffusion effect. Since the lithographic printing plate is developed to produce a screenless printing plate, when performing image exposure on a positive type lithographic printing plate via a spacer film, the light diffusion effect of the spacer film, or printing with a positive image. The screening shape of the halftone dots expressing the gray scale of the positive image can be blurred by an appropriate distance between the printing plate and the photosensitive material, thereby obtaining a printing plate for screenless printing.

For each color separation halftone positive image, a lithographic printing plate for shadow tone is made by exposing the image at a large exposure amount, and a lithographic printing plate for a middle tone is made by exposing the image at a medium exposure amount. Lithographic printing with good tone reproduction in the shadow tone area, middle tone area, and highlight tone area by making a lithographic printing plate for highlight tone by exposing the image with low light exposure Plates can be easily made.

The screenless plate-making printing method of the present invention uses a lithographic printing plate obtained by making a plate in the screenless plate-making process and a lithographic printing ink diluted at an appropriate dilution ratio. To print on the surface, you can finely adjust the tone reproduction of the shadow tone area and the highlight tone area, and the gradation reproduction of the shadow tone, highlight tone, and middle tone area by the printing pressure of the printing machine is excellent. A screenless printed matter is obtained.

The screenless plate-making printing method of the present invention is divided into a printing plate for printing a screenless printing image area in a plate-making process and a printing plate for printing a normal line drawing printing area. Each printing plate is made, and a screenless printed material including a line drawing area (line drawing pattern) is obtained by overprinting the printing plate. Therefore, printing of a screenless printed material including a line drawing area (line drawing pattern) using only the screenless printing plate. In this case, the color misregistration in the outer contour portion of the line drawing area which is likely to occur in the above is hardly conspicuous.

[0060]

According to the screenless plate-making printing method of the present invention, compared with the conventional screenless plate-making method, a continuous tone (continuous stone) color separation film whose density is particularly adjusted is not required. The labor and time required for adjusting the density of continuous tone color separation films suitable for plateless printing can be saved, and shades are reproduced by halftone dots (dot patterns) screened using a contact screen or an electronic plate making device. A screenless printing plate can be easily made on the basis of a normal color separation halftone positive image, and a good screenless printed matter can be obtained using the printing plate, which occurs in screenless printing including a line drawing area (line drawing pattern). Screenless printing, such as color misregistration at the outer contour of the line drawing area In those that exhibit a remarkable effect.

[Brief description of the drawings]

FIG. 1 is a plan view of a color separation halftone positive image (film) used in the screenless plate-making printing method of the present invention.

FIG. 2 (a) is a plan view of a line drawing negative image (film) used in the screenless plate-making printing method of the present invention. (B) It is a top view of the line drawing positive image (film) used for the screenless plate-making printing method of this invention.

FIG. 3 is a side sectional view illustrating plate making of a screenless printing plate in the screenless plate making printing method of the present invention.

FIG. 4 is a schematic diagram for explaining gray-scale reproduction of a screenless printing plate in the screenless plate-making printing method of the present invention.

FIG. 5 is a plan view showing a printed matter obtained by the screenless plate-making printing method of the present invention.

FIG. 6A is a plan view of a color separation halftone positive image (film) used in the screenless plate-making printing method of the present invention. FIG. 2B is a plan view of a color separation halftone positive image (film) in which a line drawing area is used in the screenless plate-making printing method of the present invention.

FIG. 7 (a) is a schematic side view for explaining a plate making method of a printing plate for shadow tone in the screenless plate making printing method of the present invention. (B) It is an outline side view of the printing plate for shadow tones in the screenless plate-making printing method of the present invention.

FIG. 8A is a schematic side view for explaining a plate making method of a printing plate for middle tone in the screenless plate making printing method of the present invention. (B) It is an outline side view of a printing plate for middle tone in a screenless plate-making printing method of the present invention.

FIG. 9A is a schematic side view for explaining a plate making method of a printing plate for highlight tone in the screenless plate making printing method of the present invention. (B) It is an outline side view of a printing plate for highlight tone in a screenless plate-making printing method of the present invention.

[Explanation of Signs] 1 ... Color separation screen positive image (film) 1a ... Light transmitting part
1b: halftone dot image part 1C: cyan color separation halftone positive image (film) 2: gradation image area 2a: white area 3 ... line image area 3a: white area 3b
... line drawing negative image area 4 ... line drawing negative image 5 ... masking area 6 ... line drawing positive image 7 ... printing image 8 ... screenless printing image area 9 ... line drawing printing image area 9a ...
Line drawing area by screenless printing 10: Color separation halftone positive image (film) with white line drawing area white 12: Spacer film 13: Lithographic printing plate (printing plate) 14: Printing plate substrate 15: Photosensitive resin layer (photosensitive material) ) 16 ... object part 17 ...
Non-image area A: Screenless print L: Ultraviolet rays S1: Shadow tone area S2: Middle tone area S3: Highlight tone area

Continuation of the front page (56) References JP-A-3-254987 (JP, A) JP-A-3-207687 (JP, A) JP-A-56-55281 (JP, A) JP-A-55-25331 (JP) JP-A-51-61303 (JP, A) JP-A-60-224576 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 1/06 G03F 5/00

Claims (3)

(57) [Claims] 1. A color separation halftone positive image which is color-separated from a document image and a gray scale is reproduced by a halftone dot, and a solid or plain halftone line drawing positive image is formed. Or through a semi-transparent film having a light diffusion effect, image-exposing a positive-type lithographic printing plate, the line drawing positive image is image-exposing to a positive-type lithographic printing plate, and each of the image-exposed lithographic printing plates is exposed. After developing and screen-making a screenless printing plate with each color separation positive image and a normal printing plate with a line drawing positive image, a portion corresponding to the color separation positive image using a screenless printing plate on a predetermined printing medium. And printing the image portion corresponding to the line drawing positive image using a normal printing plate. 2. A positive image of each color separation halftone, which is color-separated from a document image and whose gray scale is reproduced by a halftone dot, and a line drawing positive image of a solid or plain halftone net, and each of the color separation halftone positive images is a transparent film. Or through a semi-transparent film having a light diffusion effect, image-exposing a positive-type lithographic printing plate, the line drawing positive image is image-exposing to a positive-type lithographic printing plate, and each of the image-exposed lithographic printing plates is exposed. After developing and processing a screenless printing plate with each color separation net positive image and a normal printing plate with a line drawing positive image,
A screenless plate making in which an image portion corresponding to a color separation halftone positive image is printed on a predetermined printing medium using a screenless printing plate, and then an image portion corresponding to a line drawing positive image is printed using a normal printing plate. In the printing method, when making a screenless printing plate by imagewise exposing a lithographic printing plate using each color separation halftone positive image, imagewise exposing at a large exposure amount to make a screenless printing plate for shadow tone. To make a screenless printing plate for middle tone by image exposure at medium exposure, plate making a screenless printing plate for highlight tone by image exposure at low exposure, the above normal printing plate A screenless printing plate characterized by printing on a printing medium using a lithographic printing ink diluted with an appropriate dilution ratio on the screenless printing plate using a normal lithographic printing ink. Edition printing method. 3. The screenless plate-making printing according to claim 1, wherein a diffusion sheet having a thickness of 0.01 mm to 0.2 mm is used as the translucent film having the light diffusion effect. Method.