Printing – Embossing or penetrating – Rolling-contact machines
Reexamination Certificate
2000-03-20
2002-09-03
Funk, Stephen R. (Department: 2854)
Printing
Embossing or penetrating
Rolling-contact machines
C101S142000, C101S183000, C101S424100, C101S483000, C118S046000
Reexamination Certificate
active
06443058
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention lies in the printing technology field. More specifically, the invention relates to a method for the combined printing of a print carrier or stock with two ink systems, and to a printing machine of hybrid construction having a flexo or flexographic printing unit and an offset printing unit disposed downline therefrom, for performing the method.
In recent years, a trend towards labels embellished with metal effects has intensified. In order to produce a four-color printed image bordered with a gold color, paper sheets completely covered with vapor-deposited aluminum are used in label printing works. A four-color print image is then printed onto those sheets by means of an offset printing machine. The offset inks are not printed directly onto the aluminum layer. They are printed onto a covering white primer applied to the aluminum layer. In the region of the border, the covering white primer is left out, and the offset inks black, cyan and magenta are not printed either. In order to produce a gold-colored appearance of the border, only yellow offset ink is printed directly onto the aluminum layer in the region of the border.
The use of paper sheets on which aluminum has been vapor-deposited is unfavorable, however, both from a cost point of view and from an environmental point of view (recycling). Technological problems also occur at the works which process the labels when the labels are detached from their carriers. For example, the labels of reusable, recyclable bottles have to be detached from the bottles before they are refilled. For that purpose the bottles are immersed in baths of alkaline solution. Because of the comparatively low adhesion of the covering white primer to the aluminum layer, the covering white primer and, together with this, the offset inks are already detached from the aluminum layer before the label is detached from the bottle. The detached covering white and the detached offset inks block the filters of the label removing plant.
A printing machine having a number of offset printing units, a flexo printing unit upstream of the offset printing units and a varnishing unit downstream of the offset printing units is described and shown in European patent EP 0 620 115 B1 (FIG.
2
). Using a configuration of this type it is theoretically possible to print the above-mentioned paper sheets on which aluminum has been vapor-deposited, in that the covering white basic coating is applied by means of the flexo printing unit and the four-color print is applied onto that by means of the offset printing units.
Moreover, U.S. Pat. No. 5,630,363 describes a method for the combined printing of a printing material according to the flexographic printing and offset printing principle. German published patent application DE 44 35 307 A1 describes a method for the embossing and subsequent printing of a printing material.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a novel printing machine and an associated process, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which renders it possible to produce metal effects cost-effectively on the printing materials serving for the production of labels or packaging. It is a further object to provide a printing machine by means of which the method can be implemented in a technologically beneficial way.
With the foregoing and other objects in view there is provided, in accordance with the invention, a printing method, which comprises: printing a printing material in a combined printing process with two ink systems, and thereby
first printing onto the printing material an ink selected from the group of solvent-based inks and radiation-curing inks; and
subsequently printing onto the printing material at least one offset-typical ink with an offset printing process.
In accordance with an added feature of the invention, the product is first printed with a metallic ink before being forwarded to the offset printing unit(s).
In accordance with an additional feature of the invention, the first printing step comprises printing the printing material several times with inks selected from the group consisting of solvent-based and radiation-curing inks prior to printing with the offset-typical ink.
The method according to the invention for the combined printing of a printing material with two ink systems is distinguished by the fact that the printing material is first printed with an ink which can be dried by radiation or with a solvent-containing ink—especially in each case with such a metallic ink—and is then printed with an offset ink and preferably with a number of offset inks.
With the method according to the invention, it is possible to produce labels, folding boxes or the like decorated with metal effects without the use of printing-material sheets on which aluminum has been vapor-deposited. The solvent-based or radiation-curing ink does not need to be applied to the entire area of the printing material, nor overprinted with the offset-typical ink. Therefore, no covering white primer is required either, and the problems associated with this when the labels are being detached from labelled products are also eliminated.
In a refinement of the method which develops the method according to the invention and is advantageous with regard to the achievement of a high ink layer thickness on the printing material, before being printed with the offset ink or the offset inks, the printing material is first printed at least twice, one after another, with the solvent-based or radiation-curing ink. In this case, it is possible to print twice, one after another, with precisely the same solvent-based or the same radiation-curing ink. However, it is also possible for two different solvent-based or two different radiation-curing inks to be printed one after another. For example, in one case the two solvent-based inks and in the other case the two radiation-curing inks can each differ from each other slightly in terms of their viscosity, composition or pigments.
In a refinement of the method which is advantageous with regard to spot coating of the printing material, in order to print the printing material with the solvent-based or radiation-curing ink or with the solvent-based or radiation-curing inks, the flexographic printing principle is used in each case. The solvent-based or radiation-curing ink can therefore be placed on the printing material in a manner suitable for the printed image. In printed-image regions where the offset-typical ink is printed directly onto the printing material, the printing-material coating with the solvent-based or radiation-curing ink is left out.
In accordance with another feature of the invention, which is advantageous with regard to “wet on dry” printing, after being printed with the solvent-based ink or with the solvent-based inks, the printing material is air-dried. In the case of the printing of the printing material twice, one after another, using the solvent-based ink/inks, first intermediate air-drying directly following the first printing process, and second intermediate air-drying directly following the second printing process are advantageous.
In a refinement of the method which is likewise advantageous with regard to “wet on dry” printing, after being printed with the radiation-curing ink/inks, the printing material and, put more precisely, the ink printed on it, is dried by irradiation with ultraviolet light or electron bombardment. If the printing material is printed twice, one after another, with radiation-curing inks, first UV or electron irradiation directly following the first printing process, and second UV or electron irradiation directly following the second printing process are advantageous. In many applications, however, “wet on wet” printing of the two solvent-based inks or the two radiation-curing inks can also be carried out. In this case, no intermediate drying needs to be carried out between the first and second printing process using th
Filsinger Karl-Heinz
Sauer Klaus
Stadler Peter
Zahn Erich
Funk Stephen R.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Stemer Werner H.
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