PRINTING METHOD WITH TRANSFER OF A BARRIER LAYER FOR PRODUCING HIGH GLOSS PRINTED PRODUCTS

Abstract

A printed product is produced by providing a substrate, producing at least one interlayer on the substrate, printing a printed image onto the interlayer, and forming a barrier layer on the printed image. The barrier layer is provided on the printed image by applying a barrier composition to at least one carrier, at least partially drying the barrier layer and transferring it to the printed image. Preferred substrates have an acidic precoat layer as an interlayer. Such substrates can then be varnished with glossy varnishes, to achieve particularly high gloss values.

Claims

1. A method of producing a printed product, the method comprising: i) providing a substrate; ii) applying an interlayer composition to the substrate and drying the interlayer composition to obtain an interlayer on the substrate; iii) printing a printed image on the interlayer using at least one printing medium and drying the image to form a dried printed image; iv) providing an at least partially dried barrier layer on the dried printed image by applying a barrier composition to a support, drying the barrier composition at least partially, and transferring the at least partially dried barrier layer to the dried printed image.

2. The method according to claim 1, which further comprises, following step iv), applying varnish to the at least partially dried barrier layer and drying the varnish.

3. The method according to claim 1, wherein the barrier composition is a liquid or pasty composition.

4. The method according to claim 1, wherein the barrier composition comprises at least one water-based varnish.

5. The method according to claim 1, wherein the at least one interlayer composition is selected from precoats for water-based inkjet inks.

6. The method according to claim 1, wherein the intermediate layer has an acidic pH value.

7. The method according to claim 1, wherein the at least one printing medium is selected from water-based inkjet inks.

8. The method according to claim 1, wherein the at least one support is a printing unit cylinder of a printing press.

9. The method according to claim 1, wherein step iv) comprises the following method steps: a) applying the barrier composition to a secondary cylinder of a printing press; b) at least partially drying the barrier composition on the secondary cylinder of the printing press to obtain an at least partially dried barrier layer on the secondary cylinder of the printing press; and c) transferring the at least partially dried barrier layer from the secondary cylinder of the printing press to a primary cylinder of the printing press, to thereby transfer the at least partially dried barrier layer to the dried printed image.

10. A method, comprising: providing an acidic precoat layer printed with water-based inkjet ink; producing an at least partially dried layer of at least one water-based varnish without contact with the acidic precoat layer; and transferring the at least partially dried layer of the at least one water-based varnish as a barrier layer onto the acidic precoat layer printed with water-based inkjet ink to increase a gloss of a varnish layer applied over the barrier layer.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0018] The sole FIGURE of the drawing is a flow chart illustrating the method according to the invention.

DESCRIPTION OF THE INVENTION

[0019] Referring now to the FIGURE of the drawing in detail, the invention relates to a method for producing a printed product, in which [0020] i) a substrate is provided, [0021] ii) at least one interlayer composition is applied to the substrate and dried to obtain an interlayer on the substrate, [0022] iii) a printed image using at least one printing medium is printed on the interlayer and dried; and [0023] iv) an at least partially dried barrier layer is provided on the dried printed image.
In step iv), the at least partially dried barrier layer is provided on the dried printed image by applying a barrier composition to at least one support, drying it at least partially and transferring it to the dried printed image.

[0024] In principle, all materials which can be coated are suitable as substrates for step i). Substrates that are preferred are those which can be processed in printing presses. Particularly preferred substrates are those selected from plastics, paper, and cardboard.

[0025] In step ii), at least one interlayer composition is applied onto the substrate, dried, and an interlayer is thus obtained on the substrate. In principle, all types of compositions, preferably liquid compositions, are suitable as interlayer compositions, which, after a drying operation, lead to a solid layer on the substrate, preferably on the substrates mentioned as particularly preferred. Preferred interlayer compositions are those that can be dried thermally, by UV radiation, by electron radiation, or combinations thereof.

[0026] Preferred interlayer compositions are selected from precoats for inkjet inks, particularly preferably precoats for water-based inkjet inks. Such precoats are, in principle, known to those of skill in the pertinent art.

[0027] In a preferred embodiment, the interlayer obtained after drying has an acidic pH value. In this embodiment, an interlayer composition having an acidic pH value is preferably applied in step ii).

[0028] The interlayer composition can be applied in step ii) by methods known in principle from the prior art. Preferred methods are selected from printing, particularly preferably offset printing, flexographic printing, screen printing or inkjet printing, spraying, doctoring, coating, dipping and combinations thereof. Most preferably, the interlayer composition is applied in step ii) using a flexographic printing method.

[0029] In a preferred embodiment of the invention, the drying of the interlayer composition in step ii) is performed thermally, by the action of UV radiation, by the action of electron radiation, or combinations thereof. Suitable heat sources for thermal drying include hot air blowers or infrared lamps. Suitable UV radiation sources for drying by UV radiation include UV lamps.

[0030] In step iii), a printed image is printed onto the interlayer using at least one printing medium and the interlayer is dried. In principle, all printing methods known in the prior art are suitable as printing methods, with offset printing methods, flexographic printing methods, screen printing methods, inkjet printing methods and combinations thereof being preferred. Inkjet printing methods are particularly preferred.

[0031] In principle, all printing media in the prior art suitable for the respective printing methods, in particular those mentioned as preferred, are suitable as printing media. These can be dried in step iii) by methods known in principle from the prior art, preferably thermally, under the action of UV radiation, under the action of electron radiation, or combinations thereof.

[0032] In a particularly preferred embodiment, the printed image is printed in step iii) by means of inkjet printing. In this embodiment, the printing medium is preferably selected from water-based inkjet inks and UV inkjet inks, with water-based inkjet inks being particularly preferred.

[0033] The printed image printed in step iii) may be full-surface, i.e. a continuous layer without recesses, or may have one or more free areas, i.e. unprinted areas. It may, for example, be a grid of repeating image units.

[0034] In step iv) of the method according to the invention, an at least partially dried barrier layer is provided on the dried printed image obtained in step iii). For this purpose, according to the invention, a barrier composition is applied to at least one support, this barrier composition is at least partially dried onto the at least one support, and the at least partially dried barrier composition is transferred to the dried printed image as an at least partially dried barrier layer.

[0035] In a preferred embodiment, the barrier composition is selected from pasty and liquid compositions. It is particularly preferred that the barrier composition is liquid.

[0036] The barrier composition is converted into an at least partially dried barrier layer by at least partial drying. Preferably, in step iv), the at least partially dried barrier layer is transferred in film-like form from the at least one support onto the dried printed image. Preferred drying methods for at least partially drying the barrier composition include thermal drying, drying by UV radiation, drying by electron radiation, and combinations thereof. Thermal drying is particularly preferred as a drying method. In this preferred embodiment, drying is performed, for example, by supplying hot air or by irradiating with infrared radiation using an infrared lamp.

[0037] In principle, all compositions known in the art, which can be converted by at least partial drying into an at least partially dried layer that can be transferred to the dried printed image are suitable as barrier compositions. Preferred barrier compositions are those that can be at least partially dried by thermal drying, by UV radiation, by electron radiation, or by combinations thereof. Preferred barrier compositions are selected from thermally drying compositions, particularly preferably thermally drying inks, paints and varnishes, and most preferably thermally drying varnishes.

[0038] In a preferred embodiment, the barrier composition is selected from water-based compositions that can be thermally dried. In a particularly preferred embodiment, the barrier composition comprises at least one water-based varnish that can be thermally dried.

[0039] Suitable as the at least one support is, in principle, any type of device capable of removably receiving and transferring an at least partially dried layer to the dried printed image, excluding the printed substrate itself. Preferably, the at least one carrier is selected from printing unit cylinders of a printing press.

[0040] In a particular embodiment, in step iv), the at least partially dried barrier layer is provided on the dried printed image by a method comprising the following steps: [0041] a) application of a barrier composition onto a secondary cylinder of a printing press, [0042] b) at least partial drying of the barrier composition on the secondary cylinder of the printing press to obtain an at least partially dried barrier layer on the secondary cylinder of the printing press, and [0043] c) transferring the at least partially dried barrier layer from the secondary cylinder of the printing press to a primary cylinder of the printing press, which transfers the at least partially dried barrier layer to the dried printed image.

[0044] In this particular embodiment, the preferred barrier composition and printed image are those mentioned herein as preferred. The secondary cylinder is understood to be a cylinder of the printing press that is different from the primary cylinder, which transfers the at least partially dried barrier layer onto the dried printed image. The secondary cylinder may, for example, be the plate cylinder of an offset printing unit and the primary cylinder may be the blanket cylinder of the offset printing unit.

[0045] In a preferred embodiment, the method according to the invention comprises a step v) following step iv), in which at least one varnish is applied to the at least partially dried barrier layer and dried. The at least one coating can be applied by methods known in principle in the prior art, for example, by printing, particularly preferably offset printing methods, flexographic printing methods, screen printing methods or inkjet printing methods, spraying, doctoring, painting, dipping or combinations thereof. The at least one applied coating can be dried by methods that are known in principle in the prior art, for example, thermally, with UV radiation or electron radiation.

[0046] Glossy coatings are preferred as coatings for step v), especially preferably those with high gloss values. In a particularly preferred embodiment, a glossy coating selected from water-based coatings is applied in step v). Water-based coatings are known in principle in the prior art. Such varnishes contain water and dry thermally under the action of heat, the water contained in the varnish being substantially removed during the drying process. Suitable heat sources for thermal drying include, for example, hot air blowers or infrared lamps.

[0047] Another aspect of this invention relates to the use of an at least partially dried layer of at least one water-based varnish as a barrier layer on an acidic precoat layer printed with water-based inkjet ink, wherein the at least partially dried layer of the at least one water-based varnish is prepared without contact with the acidic precoat layer to increase the gloss of a varnish layer applied over the barrier layer.

[0048] By using the method according to the invention, printed products comprising acidic precoat coatings can be coated with conventional glossy coatings in printing presses to obtain printed products with high gloss values.

EXAMPLES

Example 1

[0049] A printed product is produced in a printing press according to the method of the invention, the underlying substrate having an acidic precoat layer. After the transfer of the dried barrier layer, the printed product was coated with a water-based dispersion varnish. As a result, gloss values, measured according to ISO 2813 with a measuring geometry of 60°, of about 50 to 65 gloss units were obtained.

Comparative Example

[0050] A printed product was produced as in example 1, but without a barrier layer. Gloss values of about 30 to 45 gloss units, measured using the same method as in example 1, were obtained as a result.