JPH11105258A - Ink supplying device for gravure printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a satisfactory print surface by incorporating a waveform shape in a section perpendicular to a shaft of a gravure plate cylinder in an inside surface of an ink fountain, thereby disordering flow of ink to a turbulent flow, and dissolving solid content retained in a cell of the cylinder. SOLUTION: A cylinder is covered 50% or more with an ink fountain 6 to shorten time for exposure with the air. Thus, it largely makes use of scarcely bringing about plate clogging of a basic problem of a gravure printing. Thus, solvent having high vapor pressure can be used. This contributes to conservation of energy of a drying process after printing, and largely broadens a selecting range of designing ink composition. At the time of introducing the ink from an ink introducing tube 4 to the fountain 6 and then feeding in the same direction as rotation of a gravure plate cylinder 3, a shape of a longitudinal sectional surface of an inside surface of the fountain 6 is in a waveform shape. Thus, flow of the ink is disordered to a turbulent flow by the end of the waveform shape and a distance L of the plate cylinder from the end of the shape, and solid content of the ink retained at a bottom of the cell is dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink supply device for a gravure printing machine for supplying ink to a gravure plate cylinder.

[0002]

2. Description of the Related Art Conventionally, as an ink supply device for a gravure printing machine, a furnisher roll is rotated to draw up ink in an ink fountain and deposit ink on the gravure plate cylinder to form the ink on the gravure plate cylinder. Recess (cell)
After filling the inside of the gravure plate cylinder, the excess ink adhering to the gravure plate cylinder is scraped off by a doctor, and the ink in the cell is applied to a printing material such as paper supplied between the gravure plate cylinder and the impression cylinder. 2. Description of the Related Art An ink supply device (ink-dipping roller system) of a gravure printing machine for transferring images is known.

[0003]

The gravure printing press has a structure in which the ink in the ink fountain is supplied to the cells by rotation of a furnisher roll or the gravure plate cylinder itself. During high-speed rotation of the ink, the ink adhering to the finisher roll or the gravure plate cylinder is easily scattered to the surroundings, and the ink that has been scraped off by the doctor due to the strong flow of ink in the ink fountain due to rotation or into the ink fountain When the ink drops, bubbles are entrapped in the ink, and the quality of printed matter is degraded. In addition, the scattering of the ink causes the ink to adhere to various parts of the gravure printing machine, so that time has been spent for cleaning to maintain the aesthetic appearance.

[0004] A general feature of gravure printing is that the cells on the gravure plate cylinder are filled with ink in an ink supply device, and excess ink adhering to the plate cylinder is scraped off by a doctor so that the ink is left only in the cells. A filled state is created, and then the ink filled in the cells is transferred to a substrate for printing to form a printed image.

[0005] Since the ink in a cell is not usually transferred 100%, even if the transfer is performed, some ink remains at the bottom of the cell. The ink at the bottom of this cell is exposed to air until the gravure plate cylinder rotates and comes into contact with the ink again, so that the solvent of the ink evaporates and only the solid content of the ink remains at the bottom of the cell. Remains. When the ink is solidified at the bottom of the cell and enters the ink supply device again, the solidified ink at the cell bottom is dissolved again by the ink that is rich in solvent components and has high fluidity. Solidified ink will deposit on the bottom of the cell without complete dissolution. When the solidification of the ink is repeated, the depth of the cells becomes shallower, and the amount of transfer of the ink to the substrate to be printed becomes smaller as the operation proceeds for a long time. The ink is completely filled with the solidified ink, and a state of clogging of the plate where the ink cannot be transferred is obtained. In such a state, the temporary operation must be stopped, the gravure plate cylinder must be washed, and the solidified ink deposited on the bottom of the cell must be wiped off.

Therefore, in performing gravure printing, it is necessary to pay attention to the determination of the ink composition, to add a solvent having a low vapor pressure in order to suppress the evaporation of the solvent, or to remove bubbles from the need to prevent the generation of bubbles. It was necessary to add an agent and the like. Addition of a solvent having a low vapor pressure affects the drying process after printing, and requires a long drying device to obtain good quality printed matter, and requires a large amount of energy because high temperature hot air is required. Had to be consumed.

[0007] In order to reduce the change in the composition of the ink, closed-type doctors have been developed. However, since the contact distance between the ink and the plate is short (shorter than an ordinary ink fountain), these doctors are used. The gravure plate cylinder comes out of the ink fountain in a state where the ink is not filled in and the solidified ink in the cell does not dissolve again, so the ink is not filled and it has the opposite effect, and the actual gravure printing method It is difficult to use.

[0008]

In order to achieve the above object, the present invention first provides an ink fountain having a shape in which the ink fountain covers at least 50% of the gravure plate cylinder. The inner surface has a wavy shape in a cross section perpendicular to the axis of the gravure plate cylinder.

According to a second aspect of the present invention, there is provided an ink supply apparatus for a gravure printing machine according to the first aspect, wherein a radius of curvature of a front end portion of the corrugated shape satisfies 25 <R <360 mm. is there.

According to a third aspect of the present invention, there is provided an ink supply apparatus for a gravure printing machine according to the first or second aspect, wherein a distance L between the front end portion of the corrugated shape and the gravure plate cylinder satisfies 2 <L <50 mm. It is what it was.

[0011] In claim 4, claims 1 to 3
An ink supply device for a gravure printing machine according to the above, wherein the outer wall of the ink fountain is opened.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 shows a closed type gravure printing system according to an embodiment of the present invention, in which printing ink is introduced into an ink fountain 6 from an ink inlet tube 4 by a circulation pump, and then in the same direction as the rotation of the gravure plate cylinder 3. It flows and is discharged from the ink fountain 6 through the ink discharge pipe 5. The ink fountain 6 is a space sealed by the introduction-side doctor 9 and the discharge-side doctor 10.

In the present invention, the ink fountain 6 has a cylinder
% Or more can reduce the time of exposure to air,
This is very useful for making it difficult to cause plate clogging, which is a fundamental problem of gravure printing. This allows the use of solvents with a high vapor pressure, saves energy in the drying process after printing, and greatly expands the choice of ink composition design. When the ink is introduced from the ink inlet tube 4 into the ink fountain 6 and then flows in the same direction as the rotation of the gravure plate cylinder 3, the vertical cross-sectional shape of the inner surface of the ink fountain 6 has a wavy shape. The ink flow is made turbulent by the distance L of the gravure plate cylinder from the tip of the gravure plate and the tip of the wavy shape, and the solid content of the ink remaining at the bottom of the cell is dissolved, thereby eliminating the plate clogging. Thus, it is possible to obtain a good image whose quality does not change at the start and end of printing. In our experiments, we used a cylinder of φ100-φ240mm. As a result, the radius of curvature R at the tip of the corrugated shape was 25 <R <360mm. Radius of curvature R is 50
<R <150 mm. Further, the distance L from the front end of the wavy shape inside the ink fountain to the gravure plate cylinder is L> 50.
When L> 2 mm, the above effect was not exhibited. When L> 2 mm, it was very difficult to mount the cylinder due to a problem in the processing accuracy of the apparatus, and the flow of the liquid was poor during printing, resulting in printing unevenness. The liquid flow effect due to the waveform shape was remarkable 2 <
L <20 mm.

The work of replacing the gravure plate cylinder 3 can be easily performed by a mechanism for separating and attaching the ink fountain 6 as shown in FIG. The outer walls connected to each other at the bottom C of the ink fountain are centered on the bottom C, and the ink surface is the gravure plate cylinder 3.
Open on both sides away from With such a separation / removal mechanism, the gravure plate cylinder 3 can be easily replaced, and the ink adhered to the inside of the outer wall can be wiped off even when the ink fountain 6 is cleaned.

[0015]

[Comparative Example 1] In the case of a normal closed-type gravure printing press Immediately after printing is started, inking can be performed without drying the plate, but over time, the drying of the plate gradually occurs, and the image on the gravure plate cylinder is used as a basis. A good printed surface could not be obtained without sufficient transfer to the material.

[0016]

[Comparative Example 2] The radius of curvature R of the inside of the ink fountain having a wavy shape is 25 <R <3.
When the distance was less than 60 mm, neither of them could generate turbulence in the flow of ink in the ink fountain, and could not dissolve solids deposited on the bottom of the cell of the gravure plate cylinder.

[0017]

[Comparative Example 3] When the distance L between the corrugated tip in the ink fountain and the gravure plate cylinder is L <2 mm, the flowability of the ink in the ink fountain is poor and the mounting is very difficult. Was. L> 50mm
In this case, no turbulence was generated in the flow of the ink in the ink fountain, and the solid matter deposited on the bottom of the cell of the gravure plate cylinder could not be dissolved.

[0018]

According to the present invention, since the ink fountain covers the gravure plate cylinder by 50% or more, the time of exposure to air can be reduced, and the plate is less likely to be clogged. In addition, the flow of the ink is turbulent due to the presence of the wavy shape inside, and the solid content remaining in the cells of the gravure plate cylinder is dissolved,
A good printed surface can be obtained. In addition, by opening the outer wall constituting the ink fountain, it is easy to replace the gravure plate cylinder and clean the ink surface.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of an ink supply device for a gravure printing machine according to the present invention.

FIG. 2 is a schematic diagram showing a state where an ink fountain is opened.

[Explanation of symbols]

 1 ··· substrate to be printed 2 · impression cylinder 3 · · · gravure plate cylinder 4 · ink introduction pipe 5 · · · ink discharge pipe 6 · ink fountain 7 · · · ink 8 (a ), 8 (b) ··· Outer wall 9 · Inlet-side doctor 10 · Discharge-side doctor R · Curvature radius of wave-shaped tip L · · · Distance between wave-shaped tip and gravure plate cylinder C ... Bottom of ink fountain

Claims (4)

[Claims] 1. An ink fountain having a shape in which the ink fountain covers at least 50% of the gravure plate cylinder, wherein the inner surface of the ink fountain has a wavy shape in a cross section perpendicular to the axis of the gravure plate cylinder. An ink supply device for a gravure printing machine. 2. A radius of curvature of a wave-shaped R tip portion is 25 <R.
2. The ink supply device for a gravure printing machine according to claim 1, wherein <360 mm is satisfied. 3. A distance L between a wave-shaped tip and a gravure plate cylinder.
3. The ink supply device for a gravure printing machine according to claim 1, wherein the following formula satisfies 2 <L <50 mm. 4. An ink supply apparatus for a gravure printing machine according to claim 1, wherein an outer wall of the ink fountain is opened.