JPH08244194A - Letterpress printer and letterpress printing method - Google Patents

Abstract

PURPOSE: To improve the printing quality by suppressing a marginal zone. CONSTITUTION: This letterpress printer comprises a plate cylinder 16, a plate 16a provided on the outer periphery of the cylinder 16 and having a surface unevenness, and an impression cylinder 17 for pressing the plate 16a via an object 20 to be printed, wherein ink is adhered to the protrusion of the plate 16a to transfer the ink to the object 20 to be printed. A cushion layer 18 which is elastically deformed by the pressing force at the time of printing is provided on the outer periphery of the cylinder 17. The layer 18 has an uneven part on the inner peripheral side. The area of the outer peripheral side of the protrusion of the layer 18 is superposed with the protrusion of the plate 16a at the time of printing, and has the area included in the area of the protrusion of the plate 16a to be superposed. The layer 18 reduces the impression pressure of the outer edge of the protrusion of the plate 16a at the time of printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a letterpress printing apparatus and a letterpress printing method in which ink is attached to the convex portions of a plate having surface irregularities and the ink is transferred to a printing object.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a schematic configuration of a conventional relief printing apparatus. A plate 16a is attached to the plate cylinder 16. The plate 16a is one in which surface irregularities are formed such that the image area becomes a convex portion and the non-image area becomes a concave portion. Generally, zinc, copper, resin or the like is used as the material of the plate 16a. The plate 16a is manufactured by applying a photosensitive solution to the plate surface, baking a negative, and the like, and dissolving the non-image area with a nitric acid corrosive solution or the like.

Ink source roller 1 on the ink key 11 side
When ink is supplied to the calling roller 13 from 2,
The ink is kneaded by the plural kneading rollers 14 and then supplied to the inking roller 15. Here, the reason why the plural kneading rollers 14 knead the ink is to obtain various physical properties of the ink necessary for printing. And the ink is plate 1
It is attached to the convex portion of 6a. The impression cylinder 17 presses the plate cylinder 16 via the printing substrate 20 to apply printing pressure. As a result, the ink is transferred to the printing substrate 20 and printing is performed.

[0004]

However, the above-mentioned conventional letterpress printing apparatus has the following problems. FIG. 4 is a diagram showing in detail the contact state between the plate 16a and the printing substrate 20 during printing. Generally, it is difficult to maintain the surface of the convex portion of the plate 16a with high accuracy. Therefore, in order to completely transfer the surface irregularities formed on the plate 16a to the printing substrate 20, a high printing pressure is applied. As a result, there is a problem that the ink attached to the surface of the convex portion of the plate 16a overflows around the convex portion (outside the convex portion surface), and a marginal zone occurs in the printed matter. The marginal zone is preferable in some cases because it gives a feeling of edging characters and the like, but there is a problem that the dot diameter changes in the dot pattern.

The present invention has been made to solve the above problems, and an object of the present invention is to suppress the occurrence of marginal zones and improve print quality.

[0006]

In order to achieve the above-mentioned object, the invention of claim 1 (topographic printing apparatus) comprises a plate cylinder (1
6), a plate (16a) provided on the outer periphery of the plate cylinder and having surface irregularities, and an impression cylinder (17) for pressing the plate through the printing object (20), A printing press for transferring ink to the printing target by attaching ink to a printing section, comprising printing pressure reducing means for reducing printing pressure at the outer edge of the projection of the printing plate. To do.

According to a second aspect of the present invention, in the letterpress printing apparatus according to the first aspect, the printing pressure reducing means is provided on an outer peripheral portion of the impression cylinder, and is a cushion layer which is elastically deformed by a pressing force during printing ( 18), wherein the cushion layer has an uneven portion on the inner peripheral surface side, and the region on the outer peripheral surface side of the convex portion of the cushion layer overlaps with the convex portion of the plate at the time of printing, and overlaps with the convex portion. It has a region included in the region of the convex portion of the plate. According to a third aspect of the present invention, in the letterpress printing apparatus according to the second aspect, the convex portion of the cushion layer has an area of 80 to 9 in a region of the convex portion of the plate overlapping with the convex portion.
It is characterized by having an area of 0%.

According to a fourth aspect of the present invention (a letterpress printing method), there is provided a plate cylinder, a plate provided on the outer periphery of the plate cylinder and having surface irregularities, and an impression cylinder for pressing the plate through a printing object. A plate printing method in which ink is attached to the convex portions of the plate and the ink is transferred to the printing object, wherein the printing pressure at the outer edge of the convex portions of the plate is reduced. To do.

[0009]

In the first and fourth aspects of the invention, when the printing object is pressed against the plate by the impression cylinder, the ink attached to the convex portions of the plate is transferred to the printing object. At this time, the pressure acting on the outer edge portion of the convex portion of the plate is smaller than the pressure acting on the central portion of the convex portion. Therefore, it is possible to reduce the amount of ink squeezing out around the convex portion (occurrence of a marginal zone). According to the second aspect of the invention, the pressure of the outer edge portion of the convex portion of the plate is reduced by the action of the cushion layer during printing.
In the invention of claim 3, the area of 80 to 90% of the convex portion of the plate overlaps the convex portion of the cushion layer. Therefore, it is possible to reduce the occurrence of marginal zones while maintaining an appropriate overall printing pressure.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a relief printing apparatus and a relief printing method according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an embodiment of a letterpress printing apparatus according to the present invention. The present invention is different from the letterpress printing apparatus shown in the conventional example in that the impression cylinder 17 is provided with the cushion layer 18. Other configurations are similar to those of FIG. The cushion layer 18 is an impression cylinder 17
It is attached to the outer periphery of. The cushion layer 18 is
It is made of resin or rubber, and its hardness is
For example, a Shore D hardness of about 30 ° or a Shore A hardness of 80
It is about ゜. Therefore, the cushion layer 18 has some elasticity.

An uneven portion is formed on the inner peripheral surface side of the cushion layer 18. An area on the outer peripheral surface side of each convex portion of the uneven portion overlaps each convex portion of the plate 16a at the time of printing, and is included in the overlapping convex region of the plate 16a.
For example, it has an area of about 80 to 90% of the area of the convex portion of the plate 16a.

As a method for producing the cushion layer 18, for example, when exposing the photosensitive resin, the film used at the time of printing the printing plate is turned upside down to use a convex portion smaller than the actual convex portion of the plate 16a. To be formed. Alternatively, when the photosensitive resin is exposed to light, the film is turned over to prepare and use a film having small protrusions. Alternatively, when a printing plate is performed by a digital method, image data is corrected to form a convex portion smaller than the printing plate. The cushion layer 18 formed in this manner is attached to the impression cylinder 17 so that the impression cylinder 17 side is the uneven side. In addition, positioning is performed using a registration mark or the like.

FIG. 2 shows the printing plate 16a and the printing substrate 2 during printing.
It is a figure which shows the contact state with 0 in detail. In FIG.
At the time of printing, with the ink adhered to the convex portions of the plate 16a, the cushion layer 18 is transferred to the plate 16a via the printing substrate 20.
Is pressed by. Here, the convex portion of the plate 16a and the convex portion of the cushion layer 18 overlap each other, but the region of the convex portion of the cushion layer 18 is arranged in the region of the convex portion of the plate 16a in the thickness direction. That is, the central portion of the convex portion of the plate 16a overlaps the convex portion of the cushion layer 18, but the outer edge portion of the convex portion of the plate 16a is
It does not overlap with the convex portion of the cushion layer 18. Therefore, edition 16
The pressure acting on the outer edge of the convex portion of a becomes small. As a result, the ink hardly leaks from the periphery of the convex portion of the plate 16a, and the occurrence of marginal zones is reduced.

[0014]

According to the first, second and fourth aspects of the present invention, it is possible to reduce the amount of ink squeezing out (generation of marginal zone) around the convex portions of the plate. Therefore, the print quality can be improved. Further, according to the third aspect of the present invention, it is possible to reduce the occurrence of marginal zones while maintaining an appropriate overall printing pressure.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a relief printing apparatus according to the present invention.

FIG. 2 is a diagram showing in detail the contact state between the plate 16a and the printing substrate 20 during printing.

FIG. 3 is a diagram showing a schematic configuration of a conventional letterpress printing apparatus.

FIG. 4 is a diagram showing in detail the contact state between the printing plate 20 and the plate 16a during printing.

[Explanation of symbols]

 16 plate cylinder 16a plate 17 impression cylinder 18 cushion layer 20 printing substrate

Claims (4)

[Claims] 1. A plate cylinder, a plate provided on the outer periphery of the plate cylinder and having surface irregularities, and an impression cylinder that presses the plate through an object to be printed, and ink is applied to the convex portions of the plate. A letterpress printing apparatus that adheres and transfers the ink to the printing target, comprising a printing pressure reducing unit that reduces the printing pressure of the outer edge portion of the convex portion of the plate. . 2. The relief printing apparatus according to claim 1, wherein the printing pressure reducing means is a cushion layer provided on an outer peripheral portion of the impression cylinder and elastically deformed by a pressing force during printing. Has an uneven portion on the inner peripheral surface side, the region on the outer peripheral surface side of the convex portion of the cushion layer overlaps the convex portion of the plate during printing, and the region of the convex portion of the plate that overlaps A letterpress printing apparatus having an area included in 3. The relief printing apparatus according to claim 2, wherein the convex portion of the cushion layer has an area of 80 to 90% of an area of the convex portion of the plate overlapping with the convex portion. Printing device. 4. A plate cylinder, a plate provided on the outer periphery of the plate cylinder and having surface irregularities, and an impression cylinder that presses the plate through an object to be printed, and ink is applied to the convex portions of the plate. A letterpress printing method of adhering and transferring the ink to the printing object, comprising reducing a printing pressure of an outer edge portion of the protrusion of the plate.