JPH0780341B2 - Screenless printed matter and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a platemaking and printing technique for easily producing and providing a screenless (halftone-free) printed matter such as a lithograph with a small number of pictures. Regarding

[Prior art]

The printed matter is usually composed of halftone dots having a regular array in letterpress printing and planographic printing, and is composed of halftone dots or cell depth in intaglio printing, and gradation can be obtained by changing the area of ink film and the thickness of film. expressing. For this reason, normal lithographic printing has a regular array of dots and expresses density gradations depending on the size of the dots, so there is a certain limit to approaching a photographic original.

Lithography is one field of screenless (halftoneless) printed matter. But to make a lithograph,
Experts write each separation by handwork while looking at the pictures that will be the manuscript. Since 20 to 30 plates are produced from this plate, it takes a lot of patience and usually takes a long time, and it becomes an expensive printed matter (print).

Lithography has great value in the field of art,
I can't easily make a plate.

A method of producing a screenless printed matter by closely adhering the continuous decomposition film to a PS plate (presensitized plate) for lithographic printing and developing it has been tried many times in the past, but the PS plate itself produces halftone dots. Since it is intended to reproduce,
Even if the continuous-tone decomposition film is printed, the gradation will be very hard. Therefore, even if the continuous separation film is exposed by contact and printed with a developed plate, the gradation reproduction density range has a reflection density of only about 0.6, so the density range of the continuous separation film is sufficient. I can't reproduce it. Therefore, simply printing the continuous tone decomposition film on a PS plate and printing it will not produce a product with satisfactory quality.

[Problems to be Solved by the Invention]

As described above, it is an object of the present invention to provide a screenless printed matter that reproduces the full tone of an original using a continuous-tone dividing film and a PS plate for lithographic printing, which have been difficult in the past, and a manufacturing method thereof.

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides a highlight tone, a middle tone, and a shadow tone of a document in a step of printing a continuous tone color separation film used in conventional gravure on a plate material for lithographic printing. In order to reproduce each gradation, the plate was prepared by changing the amount of exposure to express the gradation of only the highlight, middle and shadow parts, and the lithographic ink and medium were mixed and diluted to adjust the thickness. Provided are a method for producing a screenless printed matter and a screenless printed matter which reproduce the full tone of a document by overprinting with a printing ink corresponding to each tone.

[Action]

By using the above means, it is possible to easily produce a screenless printed matter using a continuous color separation film and a PS plate for lithographic plate.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Fig. 1 shows the continuous density film having a transmission density of 1.8 printed on a PS plate for lithographic printing and offset printing. The reflection density is measured. The horizontal axis indicates the transmission density of the continuous resolution film and the vertical axis indicates the reflection of the printed matter. An example of a tone reproduction curve in which the density is plotted is shown. In this example, when the density of the continuous tone decomposition film is 0.5 or less, the ink does not adhere at all, the tone of the highlight part cannot be expressed, and it is the whiteness of the paper.
The above shows that the ink becomes solid (same as 100%) and the tone of the shadow part cannot be expressed.

FIG. 2 is a tone reproduction curve plotted in the same manner as in FIG. 1, but the exposure amount is changed to large 3, medium 2, and small 1. This means that the tones of highlight, middle and shadow can be partially expressed by changing the exposure amount for printing continuous tone separation film on the PS plate.

Fig. 3 shows the printing of continuous tone separation film on PS plate. The plate for each tone is made according to the exposure amount of highlight 4, middle 5 and shadow 6, and the gradation reproduction is printed with the corresponding plate ink. It represents a curve.

FIG. 4 shows a gradation reproduction curve when the highlight, middle, and shadow plates of FIG. 3 are overprinted by registering with the ink for each plate.

As shown below, to reproduce the full tone of the original, yellow,
For each of the disassembled plates such as red, indigo, and black, make and reprint plates for each tone such as highlight, middle, and shadow.

Next, examples of actual conditions will be described.

The exposure dose for producing a plate for highlight tone is 1 / of the exposure dose for exposing a halftone (or halftone negative) for ordinary planographic printing.
Offset process ink 5 to the plate exposed at 3-1 / 5
Printing is performed with ink that has been adjusted with 10 parts and 90 to 95 parts of medium, and to express the tone of only the highlight part.

As an exposure amount for producing a plate for middle tone, 30 to 50 parts of process ink and 50 parts of medium are printed on a plate baked at an exposure amount equivalent to that for exposing a net positive (or half negative) for a normal lithographic plate. ~ 70 copies are printed with the adjusted ink to express the middle tone.

The amount of exposure for producing a shadow tone plate is 3 to 3 of the amount of exposure for exposing a halftone (or halftone negative) for ordinary planographic printing.
Printing is performed with 100 parts of process ink on a plate exposed at 4 times.

As mentioned above, the gradation reproduction range of the printed matter is enlarged by overprinting with the plate showing the gradation of the highlight, middle, and shadow, and the process ink corresponding to this and the ink adjusted with the medium in register. And a high quality screenless printed matter was obtained.

The above embodiment has been described with respect to the three editions of highlight, middle, and shadow, but it is not necessarily limited to the third edition, and if necessary, highlights from middle, middle from highlight, middle from shadow, shadow from middle, etc. Separations can be made.

Also, unnecessary documents such as those without shadows can be omitted.

〔The invention's effect〕

In the present invention, the continuous tone separation film decomposed by an ordinary color scanner or the like can obtain a color separation plate for each tone only by changing the exposure amount, and it is not necessary to prepare a color separation plate by handwork.

In addition, since it is based on the general coloring principle of process inks, it is easy to set standards for plate making and printing operations, and color reproduction is relatively easy.

[Brief description of drawings]

Fig. 1 shows an example in which the continuous density film is printed on a PS plate for lithographic printing and offset printing, the reflection density of the printed matter is measured, and the transmission density of the continuous resolution film is plotted on the horizontal axis and the reflection density of the printed material is plotted on the vertical axis. Is. 2 to 4 are similar graphs, but the contents are different. FIG. 2 is a gradation reproduction curve when the exposure amount is changed.
FIG. 3 shows gradation reproduction characteristics when printing is performed with inks corresponding to each tone plate for highlight, middle and shadow. FIG. 4 shows the gradation reproduction when overprinting with the corresponding inks for each of the highlight, middle, and shadow tone plates and registering them. 1 ... Slight exposure amount, 2 ... Medium exposure amount, 3 ... Large exposure amount, 4 ... Highlight plate and highlight ink, 5 ... Middle plate and middle ink, 6 ... Shadow Ink and shadow ink

Claims (2)

[Claims] 1. To reproduce the gradations of a highlight tone, a middle tone and a shadow tone of an original in the process of printing a continuous tone color separation film used in conventional gravure on a plate material for lithographic printing. In addition, it is possible to prepare a color separation plate that expresses the gradation of only the highlight, middle, and shadow parts by changing the exposure amount, and printing ink corresponding to each tone that is prepared by mixing and diluting the planographic ink and the medium. A method for producing a screenless printed matter, which is characterized in that the full tone of an original is reproduced by overprinting with. 2. A screenless printed matter produced by the method according to claim 1.