JPS6051704B2 - Manufacturing method of resin gravure cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a resin gravure cylinder.

A resin gravure cylinder is manufactured by first preparing a cylindrical substrate, coating its surface with a photosensitive resin liquid and drying it, then baking an original plate such as a mesh positive film onto the resin layer, and then developing it.

By the way, in gravure printing, the cylindrical substrate mentioned above must be recycled for economic reasons.

This recycling is performed by cutting the resin layer with a knife or the like and peeling it off from the cylinder surface. However, the surface of the cylindrical substrate is easily scratched by the use of cutlery, and the scratches on the substrate surface will harm the smoothness of the resin layer surface when the photosensitive resin layer is again formed on the surface, and ultimately the printing will be affected. Affects quality↓μm▼1゛-U-p, l-J-“↓1
The only option is to remove the scratches by polishing the surface of the L side, or increase the coating thickness of the photosensitive resin layer. In addition, the surface of the base is easily rusted. Rust causes problems similar to the scratches described above, and changes the surface reflectance. Therefore, the surface of the cylindrical substrate is required to be hard and rust-resistant.

On the other hand, when manufacturing a resin gravure cylinder, prevention of halation must be taken into consideration during exposure.

Halation is an extremely harmful phenomenon in which the J printing light is reflected on the surface of the cylindrical substrate, curing the photosensitive resin layer over a wider area than necessary and making the gravure cell shallower. Methods for preventing halation include, for example, mixing an antihalation agent into the release layer itself, or performing a chemical conversion treatment such as chromate treatment on the surface of the cylindrical substrate in advance to change the color from gray to pale black. It is conceivable to do so. Halation can be prevented to some extent by any of these methods.

However, better prevention of halation means that the photosensitive resin layer can be made thinner. Since photosensitive resins are expensive, increasing the antihalation effect will lead to more economical production of cylinders. The present invention has been made in view of the above points.

In other words, black chrome plating or black nickel plating is applied to the surface of the cylindrical substrate before the resin layer is deposited thereon. By doing this, the anti-halation effect of the saw layer can be enhanced, the thickness of the resin layer to be applied can be reduced, and this layer can also function as a release layer and a protective layer for the substrate surface. This is what we are trying to do. Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the manufacturing process of a resin gravure cylinder having an endless resin layer as a plate surface according to the present invention.

During manufacturing, first a cylindrical base 10 is prepared (1)
.

This substrate has a metal surface such as iron. A layer 12 such as copper plating may be applied to the surface thereof. An antihalation layer 14 is formed on the surface of this cylindrical substrate 10 in advance. The purpose of the antihalation layer is to reduce the amount of scattered light reflected from the substrate side when exposing the photosensitive resin layer to form a soluble portion, thereby preventing the overall soluble portion, that is, the cell, from becoming unnecessarily shallow. It is provided in This layer 14 is made of black chrome plating or nickel (■). A photosensitive resin liquid 16 is applied from above the layer 14 .

The photosensitive resin layer 16 is made of a photocurable polyamide resin, and is formed by coating by an appropriate method such as a dipping method, a spray method, a roll coating method, or a knife blade coating method (■).

Here, an example of the knife blade coating method will be given.

In FIG. 2, 18 is a knife blade (a bar roller may be provided in place of the knife blade), and 20 is a windless heating drying device preferably incorporating a far-infrared ray generating heater.

The base body 10 is rotated counterclockwise and the blade 18 is gradually moved in the direction of the arrow. For this reason, the photosensitive synthetic resin liquid 16 is applied to the surface of the substrate and dried by radiant heat, so that it is piled up in a spiral shape without generating bubbles. As a result, an endless resin layer 16 is formed on the surface of the substrate, and this layer is formed to have a minimum thickness of about 50 μm. The above coating method achieves the above film thickness continuously and efficiently compared to dip methods, spray methods, etc.
It is also very advantageous in that it can be applied without creating bubbles, which ultimately leads to a thinner film. After the above coating step, the substrate 10 is left to cool at room temperature or is forcibly cooled.

After cooling, many undulations are observed on the surface of the endless resin layer 16. In addition to waviness, a step difference that occurs at the end of the resin film upon completion of the coating process is also observed. Gravure printing is
Since this is a so-called intaglio printing method in which the ink in the non-image areas is scraped off with a doctor and the ink remaining in the cells is transferred to the paper, the cylinder surface is required to have extremely high level of smoothness.

Normally, even if there is an unevenness of about 1 to 2 μm, printing will be uneven. Furthermore, since the resin plate has high ink receptivity, it is necessary to have a surface smoothness level equal to or higher than that of a gravure cylinder with a metal surface.

Therefore, after the above coating step, a step of removing irregularities such as waviness generated on the surface of the endless resin layer 16 and a step of smoothing the surface of the endless resin layer from which the waviness and the like have been removed are performed.
The process of removing undulations and the like is performed by rough polishing by striking the endless resin layer 16 with the polishing sheet 22 while rotating the wheel 24 on which the polishing sheet 22 is radially provided (■).

Note that removal of undulations and the like can also be done by cutting with a cutting tool or the like.

The next smoothing step is performed by final polishing using a finishing buffing wheel (not shown) and an abrasive.

Further, this finish polishing is preferably divided into rough finish polishing, which roughly removes scars generated in the process of removing undulations, etc., and finish polishing, which is performed subsequent to this.

Incidentally, the above-mentioned polishing is performed by using a lathe, for example.

In this case, the cylinder is mounted on the headstock, and the wheel and buffing wheel are installed on the carriage. When the polishing process as described above is completed, the sensitivity restoration process of the endless resin layer 16 is then performed.

This can be done, for example, by immersing the entire cylinder of the endless resin layer in simple water or water containing a soluble solvent, or placing it in an atmosphere in which only a mixture of these or a soluble solvent is vaporized.
Alternatively, oxygen substitution may be performed in an inert gas such as nitrogen or carbon dioxide. However, this step is optional. Thereafter, a halftone positive original plate 26 having an original image is applied to the smoothed endless resin layer surface and exposed to light to form a latent image (■).

After this, the cylinder is immersed in a developer, and the resin layer 16 is developed (■).

Although most of the soluble portion is removed by the development process, a rinsing step (2) is desirably added to further remove the residue, such as the developer containing the soluble portion.

The rinsing step is mainly carried out to prevent the above-mentioned residue from curing in the subsequent post-exposure step, causing the cells to become shallow or causing unevenness on the surface of the resin layer.
For example, if the developer is a solution of ethanol and water (8:2), this can be done by washing the plate surface with fresh ethanol. After the rinsing process, the cylinder is dried in a pinching device 28 that has a built-in heat source such as a far-infrared heater.
The rinse solution or developer is removed from the resin surface (■)
.

Thereafter, it is subjected to post-exposure (■) and then heated and dried.

Post-exposure accelerates the curing of the resin layer, and heat drying removes the solvent contained in the resin layer to increase the hardness of the resin layer, thereby improving printing durability. The resin gravure cylinder thus obtained has cells whose size and depth change depending on the density of the original image.

When the cylinder is reused after printing is completed, the coating 16, which is a resin layer, is cut out at the end of the cylinder with a knife 30, as shown in FIG. It is peeled off and removed.

A new resin layer can be immediately deposited on the surface of the plating layer.

Note that the steps (■) (■) of forming the photosensitive resin layer 16 in an endless shape on the surface of the plating layer 14 and the steps (■ to ■) of forming the gravure cell on the photosensitive resin layer 16 are other known steps. It can be replaced by

Now, in the present invention, as described above, the black chrome plating layer or the black nickel plating layer 14 is formed on the surface of the cylindrical substrate 10, the photosensitive resin layer 16 is formed thereon, and then the gravure cell is formed. When a gravure cell is formed, the occurrence of halation in the plating layer 14 can be extremely reduced. This means that the thickness of the photosensitive resin layer 16 can be made as small as possible, and the consumption of the expensive resin can be reduced, making the production of resin gravure cylinders economical. In addition, since the surface of the plated layer that achieves the anti-halation effect is extremely hard, even if the resin layer is cut and removed with a knife or the like when recycling the gravure cylinder, the base surface is unlikely to be deeply scratched. Rust also occurs, and the resin layer can be peeled off and removed from the substrate surface very easily. Examples of the present invention are described below. Example 1 Black chromium was electroplated to a thickness of about 5μ on an iron support, and 36
The surface reflectance at 5 nm was measured and was approximately 5%.

Next, after applying a polyamide photosensitive resin to a thickness of approximately 5 μm, the photosensitive layer is irradiated with a 15 W/I ultra-high pressure mercury light source for 10 minutes through a positive film, and the unexposed resin layer is washed away with an ethanol developer to form a resin gravure. Got the edition. In this resin gravure plate, the cell depth is 35μ when the halftone positive area is 80% with 1 (4) lines, and as the halftone dot area decreases,
Although the cell depth also decreased, the tone reproduction of printed matter was good. When the resin was peeled off after use, there were no deep scratches on the surface and the removal operation was extremely smooth.

When a resin gravure plate was produced using the same process, the tone reproducibility was also the same. Example 2 When black nickel was plated with a thickness of about 10 μm on a copper support, the thickness was 365 nm.
The surface reflectance was about 10%, and a resin gravure plate was produced in the same manner as in Example 1.

This resin gravure plate had a cell depth of 30p for the same halftone positive area as in Example 1, and the reproducibility (printing quality) was also good. In this case as well, the substrate could be reused.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing process of a gravure cylinder according to the present invention.

Claims (1)

[Claims] 1. Manufacturing method of resin gravure cylinder consisting of the following steps a. Step b. Forming a black chrome plating layer or black nickel plating layer on the surface of a cylindrical substrate. b. Forming an endless photosensitive resin layer on the surface of the plating layer. Step c: Forming a gravure cell on the photosensitive resin layer