JPS58224795A - Manufacture of gravure printing plate stuck to gravure printing plate cylinder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for making gravure printing plates having a polymeric printing layer applied to a flexible support of stable dimensions for application to a gravure printing plate cylinder.

To make a gravure printing plate with a plastic printing layer, the plastic layer is coated onto a suitable printing layer support;
and forming ink-accommodating depressions (ink cells) in the plastic layer by mechanical engraving (see, for example, DE 27 52 500);
or assuming a photosensitive recording material with a photopolymerizable layer coated on a support of stable dimensions, on which this photopolymerizable layer is coated, for example by a screen or line positive, or by a continuous tone positive with a screen original. The unexposed components of the layer are washed away by means of a developer (for example as described in German Patent Application No. 2), while the unexposed components of the layer are washed out by means of a developer, while the ink cell and screen structures are subsequently formed (image-wise by exposure to actinic radiation). (Specification No. 154B33, No. 2061287
Specification of No. 3128949, No. 3128
(See specification No. 951 and d → specification No. 47-41361).

For rotary gravure printing, such gravure printing plates are generally applied to a cylinder by means of a suitable adhesion device. Suitable plate cylinders having cylinder channels with means for attaching and tensioning printing plates are known and likewise described in the literature (for example, US Pat.
57621).

In this case, the problem is that there is a gap between the butts of the printing plates when pasting them together. To prevent the doctor oriented parallel to the cylinder axis from being pushed into the gap during printing and causing the doctor to bounce and thus damage the doctor and the printing plate, the printing plate is pasted onto the cylinder and the gap is closed. It has already been proposed to extend slightly obliquely to the cylinder axis. Therefore, even when the doctor is pushed into this gap and the doctor is prevented from bouncing, the gap is filled with ink that cannot be scraped off during printing, so this gap is imprinted on the printed material.
Put it away.

Many studies have already been attempted to provide printing plates that do not have butt points and can nevertheless be easily attached to cylinders. has not been successful to date. In order to prevent printing in the gaps, even now they have to be subsequently closed, for example with special plastic printing layers.

An object of the present invention is to easily and without problems attach the gravure printing plate to the cylinder without any gaps? To easily produce a gravure printing plate having a plastic printing layer that does not need to be formed.

It was surprisingly discovered that such a printing plate could be easily produced in the following manner.

That is to say, in gravure printing plates, a polymeric printing layer fixedly coated on a flexible support of stable dimensions is used to attach the plate to the plate cylinder and therefore has to be edge-bent. removed from the support within the range of .

The subject of the present invention is therefore a method for producing gravure printing plates having a polymeric printing layer coated on a flexible support of stable dimensions for application to a gravure printing plate cylinder;
This method has the following features. That is, the polymer print layer is removed in the area of the support that is to be bent for pasting.

Briefly, the subject of the invention is a special embodiment of said method, as will be described below.

The gravure printing plate according to the invention can be easily and problematically mounted on conventional gravure printing plate cylinders.

By removing the polymeric printing layer from the support according to the invention in the area of the printing plate which has been bent to attach the printing plate to the plate cylinder, in these gravure printing plates the polymeric printing layer has an original area corresponding to the cylinder circumference. extends only over the printed surface of In contrast to the conventional method in which the polymeric printing layer extends over the entire length of the printing plate and is therefore bent together and inserted into the cylinder gap when applied to the plate cylinder, there is always a gap in the printing surface at the butt point. In contrast to gravure printing plates, when applying the printing plates according to the invention, the edges of the polymeric printing layers are abutted and pressed against each other in a fixed and straight line, thus eliminating any interfering gaps that occur during printing. Without it, a surface with no butt points is obtained.

It has proven advantageous for the polymeric printing layer in the gravure printing plates according to the invention to have a layer thickness in the range from approximately 100 to 500 μm, as this results in particularly good gap closure. The edge bend line extending over the width of the printing plate in the gravure printing plate according to the invention can also run perpendicular to the long side of the printing plate and thus parallel to the cylinder axis after it has been applied, but in particular In some embodiments, these edge bend lines, which are the boundaries for removing the polymer printing layer from the support, run somewhat obliquely to the cylinder axis, i.e. not just perpendicular to the long sides of the printing plate. There is.

As supports for the gravure printing plates according to the invention, customary and well-known flexible supports of stable dimensions are used;
In particular sheet steel or aluminum sheets are used, but in some cases also suitable plastic films may be used. The polymeric printing layer, which is fixedly applied to the support by means of a suitable adhesive, can be mechanically removed from the ink-receiving recesses, for example as described in DE 27 52 500 A1. It can be a simple plastic layer to be engraved. Advantageously, however, this printed layer is a photopolymer layer, which comprises a polymeric binder, a compatible photopolymerizable ethylenically unsaturated monomer and/or oligomer, and a photoinitiator. by imagewise exposing and developing a photopolymerizable layer of a mixture of agents (DE-A-205-4833, DE 205-4833, DE-A-206-206).
] No. 287, No. 3128949, and No. 3128951).

The removal of the polymeric printing layer from the area of the support to be edged for application to the form cylinder is advantageously carried out before the actual edge-bending and is mechanically removed, for example by cutting, milling or engraving. You may go.

Given a photosensitive recording material 'f'4 having a photopolymerizable layer as described above, coated in a fixed manner on a flexible support of stable dimensions, the gravure printing plate according to the invention comprises: It can be made particularly easily and with the particular precision required. In this context, light-sensitive recording materials such as those described in German Patent Application No. 3,128,949, which is referred to herein for details regarding the composition of these recording materials and the production of gravure printing plates, have proven to be very advantageous. Ta.

The gravure printing plate according to the present invention is produced using these photosensitive recording materials in the following manner. Thus, in order to produce a printing layer, as is known, the photopolymerizable layer is imagewise exposed to actinic radiation by means of a suitable original, for example a screen or line positive or a continuous tone positive with a screen original; Forms an ink cell structure,
The unexposed components of the layer are washed and removed by a suitable developer which dissolves the unexposed components of the layer but does not dissolve the exposed components. In one embodiment of this method, which is advantageous since it is very common, the exposure of the photopolymerizable layer is carried out in such a way that the photopolymerizable layer is not exposed in the area to be bent later for application of the printing plate. Therefore, the photopolymerizable layer in these areas is removed simultaneously with the other unexposed components of the layer during washing with the developer. In order to ensure the necessary precision, the exposure of the photopolymerizable layer in this embodiment of the method according to the invention preferably takes place via registration marks. In this way, a gravure printing plate according to the invention is directly obtained which does not have a polymer printing layer in the area of the support which has to be edged in order to be applied to the plate cylinder.

Claims (7)

[Claims] (1) In a method for producing a gravure printing plate having a polymeric printing layer coated on a flexible support of stable dimensions for application to a gravure printing plate cylinder, in the area of the support to be bent for application. A method for producing a gravure printing plate applied to a gravure printing plate cylinder, characterized in that the polymeric printing layer is removed. (2) A method according to claim 1, wherein the polymer print layer in the area of the support to be bent is removed before the bending. (3) The method according to claim 1 or 2, wherein the edge bending line extending across the width of the printing plate extends obliquely to the long side of the printing plate. (4) The thickness of the polymer printing layer is approximately 100 to 500 mm
4. A method according to one of claims 1 to 3, wherein .mu.m. (5) Assuming a photosensitive recording material having a photopolymerizable layer coated on a flexible support of stable dimensions, the photopolymerizable layer is imaged by means of a suitable positive original to create a printing layer. exposure to actinic radiation according to the conditions, followed by washing of the unexposed components of the layer with a developer solution that dissolves the unexposed components of the layer but not the exposed components, and removing the support from the plate cylinder. 5. A method according to claim 1, wherein the layer is removed in areas that have to be hemmed for pasting. (6) The photopolymerizable layer is exposed to light in such a way that this layer is not exposed to light in the areas to be edged and these areas are simultaneously removed during washing with a developer solution. The method described in section. (7) A method according to claim 6, wherein the exposure of the photopolymerizable layer is carried out via registration marks.