JP2002292822A - Gravure printing method and gravure printing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the clogging of a printing plate due to the dying of an ink from occurring, even when the ink is of such a type that it contains a solvent having high evaporation rate. SOLUTION: This gravure printing method comprises the steps to transfer the ink to the plate face of a plate cylinder 1 from an ink pan 4 to perform an inking process, then scrape off an excess ink from the plate face with the help of a doctor 3 and transfer the ink clogged in the cells of the plate face to the surface of a web 5 passing through a space between the plate cylinder 1 and an impression cylinder 2 to perform the printing or coating process. In this method, the concentration of the solvent on the plate face is kept at a constant level by airtightly closing the part of the plate face in a process from inking to transfer. Even when the ink containing the solvent having high evaporation rate is used, it is possible to control the concentration of the solvent on the plate face so that no difference of the evaporation rate of the ink on the plate face occurs depending upon a printing direction or the variable density of a surrounding pictorial design. Thus, no clogging of the printing plate due to the drying of the ink occurs and consequently the keeping of a printing quality on a constant level is always achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of gravure printing, and more particularly to a gravure printing method using an ink using a solvent having a high evaporation rate, and a gravure printing machine used therefor.

[0002]

2. Description of the Related Art Gravure printing is a type of intaglio printing, in which printing is performed with a low-viscosity solvent type ink using a printing plate made by applying photographic technology. A method of expressing the density of the printed matter is adopted. That is, the fact that a large amount of ink is clogged in deep holes, but a small amount of ink is clogged in shallow holes.

[0003] This gravure printing is most suitable for high-speed printing of photographs on paper having a large number of copies and not very high quality, and is used for printing graph pages of graph magazines and weekly magazines. In addition, cellophane, various plastics,
It is also used for printing on metal foils and fabrics.

[0004]

In the gravure printing described above, with ink using a solvent having a high evaporation rate, the pattern arrangement is changed from light to shadow in the printing direction as compared with the case where the pattern is changed from shadow to light in the printing direction. If you have
Since the solvent concentration on the plate surface is low and the ink is easy to dry, there is a problem that the plate is clogged, the inking of halftone dots is deteriorated, and a predetermined printing density cannot be obtained.

In addition to the influence of the printing direction,
It may be affected by surrounding patterns. For example, 100
In the 50% flat screen sandwiched between the 10% flat screen and the 10% flat screen, the solvent concentration on the plate surface is higher in the portion closer to the 10% flat screen than in the portion near the 100% flat screen. Due to the low printing density, there is a problem that a plate jam occurs and a printing density difference occurs partially within the same flat screen.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent clogging of a plate due to drying of ink even with ink using a solvent having a high evaporation rate. And a gravure printing machine used therefor.

[0007]

In order to solve the above-mentioned problems, a gravure printing method of the present invention transfers ink of an ink pan to a plate surface of a plate cylinder to perform inking, and an extra doctor on the plate surface by a doctor. After the ink is scraped, the ink clogged in the cells of the plate is transferred to the surface of the raw material passing between the plate cylinder and impression cylinder, and printing and coating are performed by inking in the gravure printing method. By sealing the plate portion up to this point, the solvent concentration on the plate surface is kept constant.

In the gravure printing machine of the present invention, the ink in the ink pan is transferred to the plate surface of the plate cylinder to perform inking, and a doctor removes excess ink on the plate surface. In a gravure printing machine that performs printing and coating by transferring clogged ink to the surface of the raw material that passes between the plate cylinder and impression cylinder, a solvent evaporation prevention cover that seals the plate surface from inking to transfer is provided. In addition, a solvent concentration sensor is installed in the solvent evaporation prevention cover, and when the solvent concentration becomes lower than the specified value, the solvent is sprayed into the solvent evaporation prevention cover. It is preferable to maintain a predetermined concentration.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

First, the principle of the present invention will be described with reference to the graph of FIG. FIG. 1 is a graph showing the evaporation rate of a solvent in an ink using a solvent having a high evaporation rate as a change in the weight of the ink due to the evaporation of the solvent. The horizontal axis represents the elapsed time, and the vertical axis represents the weight of the ink. The greater the slope in the graph, the faster the evaporation rate of the solvent in the ink.

In the graph of FIG. 1, the surrounding solvent concentration is 0p
pm, the surrounding solvent concentration is 2800 ppm
In FIG. 1, the evaporation rate of the solvent in the ink is reduced by increasing the concentration of the surrounding solvent from 0 ppm to 2800 ppm, as can be seen from FIG. That is, since the evaporation rate of the solvent in the ink can be reduced by increasing the concentration of the surrounding solvent, in the gravure printing, the solvent concentration in the ink from the inking to the transfer is increased by increasing the solvent concentration in the ink. Evaporating speed can be reduced, and plate clogging due to plate drying can be prevented.

FIG. 2 is a schematic structural view showing an example of a printing unit in a gravure printing machine according to the present invention. In FIG. 2, 1 is a plate cylinder, 2 is an impression cylinder, 3 is a doctor, 4 is an ink pan, and 5 is printing. Each of the target webs is shown. This printing unit transfers the ink of the ink pan 4 to the plate surface of the plate cylinder 1 to perform inking, and after the doctor 3 scrapes off excess ink on the plate surface, removes the ink clogged in the cells of the plate surface. Material 5 passing between cylinder 1 and impression cylinder 2
This is a configuration in which printing or coating is performed by transferring the image to the surface of a sheet.

The printing unit shown in FIG. 2 is provided with a solvent evaporation preventing cover 6 for sealing the plate portion from inking to transfer as shown in the drawing. In addition, it is possible to keep the solvent concentration uniform at a higher level than the portion without the cover 6 and to prevent plate clogging due to plate drying.

The solvent concentration in the solvent evaporation preventing cover 6 changes depending on the density of the picture, and if the solvent concentration is low, the plate may be clogged. Therefore, FIG.
When the solvent concentration sensor 7 is mounted in the solvent evaporation prevention cover 6 as shown in FIG.
And sprays the solvent in the solvent evaporation prevention cover 6,
What is necessary is just to keep it at a predetermined solvent concentration. In addition, the operator may be alerted by outputting an abnormal signal indicating that the plate is jammed.

The present invention has been described in detail based on the embodiments. However, the gravure printing method and the gravure printing machine according to the present invention are not limited to the above embodiments, and the gist of the present invention is as follows. It goes without saying that various changes can be made without departing from the scope.

[0016]

According to the present invention, since the solvent concentration on the plate surface is kept constant in gravure printing, even when ink using a solvent having a high evaporation rate is used, the printing direction and the surrounding pattern Since the concentration of the solvent on the plate surface can be controlled so that there is no difference in the evaporation rate of the ink on the plate surface due to the shading, a constant printing quality can always be achieved without causing plate clogging due to drying of the ink.

[Brief description of the drawings]

FIG. 1 is a graph showing the evaporation rate of a solvent in an ink using a solvent having a high evaporation rate as a weight change of the ink due to the evaporation of the solvent.

FIG. 2 is a schematic configuration diagram illustrating an example of a printing unit in the gravure printing machine according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plate cylinder 2 Impression cylinder 3 Doctor 4 Ink pan 5 Raw material 6 Solvent evaporation prevention cover 7 Solvent concentration sensor 8 Pump 9 Solvent tank

Continued on the front page F term (reference) 2C250 DB11 EA23 EB50

Claims (3)

[Claims] Ink is transferred by transferring the ink of the ink pan to the plate surface of the plate cylinder, and a doctor removes excess ink on the plate surface. Then, the ink clogged in the cells of the plate surface is pressed with the plate cylinder. In the gravure printing method in which printing and coating are performed by transferring the material to the surface of the material passing between the cylinders, the plate portion from inking to transfer is sealed to maintain a constant solvent concentration on the plate surface. A gravure printing method, characterized in that: 2. Ink is transferred by transferring the ink of the ink pan to the plate surface of the plate cylinder, scraping off excess ink on the plate surface with a doctor, and pressing the ink clogged in the cells of the plate surface with the plate cylinder. A gravure printing machine that performs printing and coating by transferring to the surface of a raw material that passes between a cylinder and a gravure printing machine, wherein a gravure printing method is provided, in which a solvent evaporation prevention cover that seals a plate portion from inking to transfer is provided. Machine. 3. A solvent concentration sensor is mounted inside the solvent evaporation prevention cover, and when the solvent concentration becomes lower than a specified value, the solvent is sprayed into the solvent evaporation prevention cover to maintain the predetermined concentration. 3. The gravure printing press according to claim 2, wherein: