JPS5852580B2 - Gravure Satupan no Seizouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a gravure plate in which the size and depth of ink receiving cells are made to correspond to the shading of the original, from an original plate for offset printing (positive type, negative type) or for letterpress printing (negative type). This invention relates to a new method for producing a printing plate for gravure printing.

In the conventional plate-making method called conventional gravure, a transparent positive with continuous changes in density is used as an original plate, and a grid screen and carbon tissue or other gravure resist forming material are used to print on the gravure printing plate. Ink-receiving cells with different depths are created, and color shading is reproduced by changing the thickness of the ink film on the surface of the printing material.

On the other hand, the reproduction of shading in letterpress printing and offset printing is due only to changes in the ink adhesion area ratio, and for this purpose it is necessary to prepare an original plate that is compatible with this.

Since the plate-making form is completely different from the well-known halftone gravure original plate, a letterpress printing original plate or an offset printing original plate (generally formed with halftone dots) is used for gravure printing. Even with plate making, it was impossible to obtain high quality gravure prints.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a gravure printing plate that can obtain a high quality gravure printing plate from a letterpress printing original plate or an offset printing original plate. The purpose is to

Hereinafter, the method of manufacturing a gravure printing plate from a letterpress printing or offset printing original plate according to the present invention will be described in detail, taking as an example the case where plate making is performed from a positive type offset printing original plate.

A positive film is created from a positive master plate for offset printing by an appropriate means, and this is layered on a lithographic film or continuous tone film via a diffuser plate, and then exposed to a surface light source printer, a point light source printer, etc. from the positive film side. Exposure is performed using a commercially available contact printer to erase the halftone dots of the offset positive original to create a negative mask in which the image is expressed in shading.

Next, a lithography film or a continuous tone film is contact-printed onto the negative mask and reversed to form a positive mask.

Next, the negative mask is placed on the gravure contact screen (for negatives) and the carbon tissue is exposed to light for an appropriate time, and then the negative mask and the gravure contact screen (for negatives) are removed and replaced with the above-mentioned positive mask. was placed on the carbon tissue and exposed for an appropriate time, and then a positive film made from an offset positive original plate was placed on the carbon tissue surface instead of the positive mask and exposed for an appropriate time (the exposure procedure was reversed). In the same manner as the conventional gravure method, the image is transferred to a gravure cylinder or flat plate, developed, coated, and then eroded to obtain a gravure printing plate.

This printing plate is a printing plate produced by the gravure plate making method of the present invention.

As described in Example 1.2 below, this printing plate has the characteristics of an offset printing plate in which the ink adhesion area ratio changes depending on the density of the original, and has gravure ink receiving cells formed on the printing plate surface, and the characteristics of the cells. It has the characteristics of a gravure printing plate that continuously changes depth, making it ideal for reproducing shading in printing.

The reproduction of color shading on the printing surface of printed matter using the printing plate created according to the present invention is an ideal reproduction form that combines changes in the print ink adhesion area ratio and changes in the depth of the ink receiving cells. It has become.

Next, examples according to the present invention will be shown.

Example 1 A 150-line offset positive original plate was layered on a commercially available lithium film via two light diffusion plates, and exposed for 10 seconds at a voltage of 40 V from the positive original plate side using a commercially available contact printer to create halftone dots on the offset positive original plate. A negative mask in which the erased image is expressed in shading was developed by developing it for 60 seconds with a normal continuous tone developer.

The above-mentioned negative mask and lithographic film were overlapped, exposed to light for 10 seconds at a voltage of 40 V using a contact printer, and developed for 30 seconds with the same continuous tone developer to create a positive mask.

Layer the negative mask on a commercially available 200-line gravure contact screen (for negatives), layer this on a carbon tissue, expose the commercially available carbon tissue for 200 seconds using a commercially available high-pressure mercury lamp printing machine, and then apply the offset positive master plate to the negative mask. , instead of the gravure contact screen (for negative), a negative mask on the carbon tissue was exposed for 200 seconds at the same position as the gravure contact screen (for negative), and then the offset positive original of the carbon tissue was removed. , a positive mask was placed at the same position as the offset positive master plate, exposed for 50 seconds, transferred to a cylinder for gravure printing plates, developed and coated (corrosion prevention), and as a result of corrosion, the ink receptivity A gravure printing plate with a difference in cell depth and a change in the ink adhesion area ratio was obtained.

As a result of printing using this, a near-L gravure print was obtained by offset printing.

Example 2 Each color plate of a four-color offset positive original plate was placed on a commercially available lithographic film via two light diffusion plates, and a voltage of 45 V and 9 seconds of exposure was applied from the positive original plate side using a commercially available contact printer. A total of 4 negative masks were created by developing with a gradation developer for 55 seconds, one for each color plate, in which the image with halftone dots removed was expressed in shading.

A commercially available gravure film was superimposed on each of the negative masks for each color plate, exposed to light for 10 seconds at a voltage of 50 V using a contact printer, and developed for 70 seconds with the same developer to obtain a positive mask for each color plate.

These negative masks, positive masks, offset positive original plates, and gravure contact screens (for negatives) were printed on each carbon tissue under the same conditions as described in Example 1, and printing plates for each color were made and printed using these, resulting in offset results. A multicolor gravure print of higher quality than the print was obtained.

In the above embodiment, a negative mask was created using a positive type offset printing original plate, and the subsequent steps were explained. However, the present invention is not limited to the above, but is applicable to offset printing (negative type)
Creating a positive film from an original plate or a (negative type) original plate for letterpress printing, making a negative mask using the method described in the examples, and then manufacturing a gravure printing plate using the steps described in the examples. Of course, it is possible to do so.

Claims (1)

[Claims] 1. An original plate for offset printing (positive type, negative type), or
A positive film is created from a letterpress printing (negative type) original plate by an appropriate means, and this is layered on a lithographic film or continuous tone film via a diffuser plate, and a contact printer such as a surface light source printing machine is used from the positive film side. A negative mask is created by exposing to light to express the halftone dots of the positive film in shading, and then the negative mask is closely printed on a lithographic film or continuous tone film and inverted to create a positive mask. Then, the negative mask and the gravure contact screen (for negatives) are overlapped, and the surface of the gravure resist forming material represented by carbon tissue is exposed. Next, the negative mask and the gravure contact screen (for negatives) are removed, and the exposure position is A positive mask is layered and exposed at the same position, then the positive mask is removed, and a positive film made from an offset printing original plate or a letterpress printing original plate is placed at the same position and exposed, and thereafter this is processed according to the well-known conventional gravure plate making method. A method for producing a gravure printing plate, which comprises creating a printing plate for gravure printing. 2 Original plate for offset printing (positive type, negative type), or
A positive film is created from a letterpress printing (negative type) master using an appropriate method, and this is layered on a lithographic film or continuous tone film via a diffuser plate, and exposed from the positive film side using a contact printer such as a surface light source printing machine. Then, create a negative mask that expresses the image with the halftone dots of the positive film in shading, and then contact print the negative mask onto a lithographic film or continuous tone film and invert it to create a positive mask. , overlap the negative mask and gravure contact screen (for negatives) and expose the surface of the gravure resist forming material represented by carbon tissue. Next, remove the negative mask and the gravure contact screen (for negatives) and place the gravure contact screen (for negatives) at the same exposure position. At the position, a positive film made from an offset printing original plate or a letterpress printing original plate is overlaid and exposed,
Next, a method for producing a gravure printing plate is characterized in that a positive mask is placed in the same position as a positive film and exposed, and thereafter a printing plate for gravure printing is created using this according to a well-known conventional gravure plate making method. .