Printing Plate and Polymeric Coating Material for the Same

Abstract

The invention relates to a coating material for coating a metal or non-metal printing plate, comprising a liquid starting material which can be polymerised using UV light in order to form a polymer matrix, and comprising a filling material which can be covalently incorporated into a polymer matrix of the starting material. The filling material is of a sub-microscale size, wherein absorption of IR radiation can be brought about by the filling material in the starting material, said absorption being higher than an absorption without filling material. The invention also relates to a printing plate comprising a cylindrical main body, wherein a polymer layer is applied to at least parts of a circumferential surface of the main body, with the polymerisation thereof being induced by UV light, wherein the polymer layer has a sub-microscale filling material, and wherein a higher absorption of infrared radiation is brought about using the filling material in the polymer layer than in the polymer layer without filling material.

Claims

1-15. (canceled)

16. A coating material for coating a printing plate, the coating material comprising: a liquid starting material configured to be polymerized by UV light to form a polymer matrix; and a sub-microscale filler which is of a sub-microscale size, wherein the coating material, in addition to the sub-microscale filler, contains an additional filler, wherein the sub-microscale filler is in particle form and the sub-microscale size is in a range between 100 nm and 999 nm, wherein the additional filler is a nanoscale filler, such that the additional filler includes filler particles with a nanoscale size in a range between 1 nm and 99 nm, wherein the sub-microscale filler comprises at least one metal oxide and/or one semi-metal oxide selected from the group consisting of metal oxide coated mica, TiO.sub.2 and (Sn, Sb)O.sub.2, wherein the nanoscale filler is a metal oxide and/or a semi-metal oxide selected from the group consisting of Al.sub.2O.sub.3, SiO.sub.2, TiO.sub.2, ZrO.sub.2 and organometallic particles, wherein the sub-microscale filler is configured to be covalently bonded into the polymer matrix of the liquid starting material, wherein the nanoscale filler is included to increase wear resistance, and is covalently bonded into the polymer matrix of the liquid starting material, wherein the sub-microscale filler is configured to cause absorption of IR radiation in the liquid starting material which is higher than absorption without a filler.

17. The coating material of claim 16, wherein the liquid starting material comprises an acrylate curable by UV light.

18. The coating material of claim 16, wherein the sub-microscale filler and the nanoscale filler ensure transmission of UV radiation, such that the liquid starting material can be fully polymerized.

19. The coating material of claim 16, wherein the coating material is electrically conductive and/or not electrostatically chargeable.

20. A printing plate, comprising: a base body; and a polymer matrix including a polymer layer, polymerization of which is induced by UV light, and applied at least partially to a surface of the base body, wherein the polymer layer includes a sub-microscale filler, wherein the polymer layer, in addition to the sub-microscale filler, includes an additional filler, wherein the sub-microscale filler is in particle form with a size in a range between 100 nm and 999 nm, wherein the additional filler is a nanoscale filler, which includes filler particles with a nanoscale size in a range between 1 nm and 99 nm, wherein the sub-microscale filler comprises at least one metal oxide and/or one semi-metal oxide selected from the group consisting of metal oxide coated mica, TiO.sub.2 and (Sn, Sb)O.sub.2, wherein the nanoscale filler is a metal oxide and/or a semi-metal oxide selected from the group consisting of Al.sub.2O.sub.3, SiO.sub.2, TiO.sub.2, ZrO.sub.2 and organometallic particles, wherein the sub-microscale filler is covalently bonded into the polymer matrix, wherein the nanoscale filler is included to increase wear resistance, and is covalently bonded into the polymer matrix, wherein the sub-microscale filler in the polymer layer causes higher absorption of infrared radiation than in the polymer layer without a filler.

21. The printing plate of claim 20, wherein the polymer layer is mechanically finished after application to the base body and after polymerization.

22. The printing plate of claim 20, wherein a surface of the polymer layer is configured to be patterned with a cell pattern or a relief pattern produced by NIR radiation.

23. The printing plate of claim 20, wherein the polymer layer is opaque prior to irradiation with NIR radiation, and wherein a color change can be effected in the polymer layer by irradiation with NIR radiation.

24. The printing plate of claim 23, wherein the color change for introducing markings or codings into the polymer layer is already effected by NIR radiation with a lower intensity than the NIR radiation required for producing the cell pattern.

25. The printing plate of claim 24, wherein the marking or coding contains data that is readable by machine.

26. A method of manufacturing a printing plate with a coating material that comprises a liquid starting material configured to be polymerized by UV light to form a polymer matrix and a sub-microscale filler which is of a sub-microscale size, wherein the coating material, in addition to the sub-microscale filler, contains an additional filler, wherein the sub-microscale filler is in particle form and the sub-microscale size is in a range between 100 nm and 999 nm, wherein the additional filler is a nanoscale filler, such that the additional filler includes filler particles with a nanoscale size in a range between 1 nm and 99 nm, wherein the sub-microscale filler comprises at least one metal oxide and/or one semi-metal oxide selected from the group consisting of metal oxide coated mica, TiO2 and (Sn, Sb)O2, wherein the nanoscale filler is a metal oxide and/or a semi-metal oxide selected from the group consisting of Al2O3, SiO2, TiO2, ZrO2 and organometallic particles, wherein the sub-microscale filler is configured to be covalently bonded into the polymer matrix of the liquid starting material, wherein the nanoscale filler is included to increase wear resistance, and is covalently bonded into the polymer matrix of the liquid starting material, wherein the sub-microscale filler is configured to cause absorption of IR radiation in the liquid starting material which is higher than absorption without a filler, the method comprising: applying the coating material to a surface of a base body of the printing plate; forming a polymer layer by curing the coating material due to polymerization caused by UV radiation; and irradiating the polymer layer with NIR radiation to produce a surface pattern in the polymer layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 schematically shows a section through a print cylinder serving as a printing plate with a polymer layer according to the invention.

DETAILED DESCRIPTION

[0054] FIG. 1 shows a cylindrical base body 1, which can consist of metal, non-metal or plastic. This base body 1 is the actual print cylinder serving as a printing plate, which can be installed in a printing machine, e.g., as a gravure cylinder. Based on the example of FIG. 1, the invention is to be explained with reference to the gravure process. Similarly, the invention can also be applied to a letterpress process or to a patterning or embossing plate. The base body can also consist of plastic, glass fiber composite, carbon fiber composite or elastomer or a combination thereof.

[0055] A polymer layer 2 is formed on the cylindrical circumferential surface of the base body 1, based on a nanocomposite in which various fillers are incorporated into the polymer layer 2. The polymer layer 2 essentially consists of an acrylate or acrylate mixture curable with UV light. In addition, fillers 3 are introduced into the polymer layer 2. The fillers 3, in particular, are sub-microscale fillers whose particles or pigments are in a size range between 100 nm and 999 nm. These fillers serve to improve the absorption of infrared radiation and thus to improve laser ablation, as already explained above in the general section.

[0056] In addition, FIG. 1 shows a UV light source 4 with which UV radiation 5 can be generated. The UV radiation 5, in particular, serves to polymerize the flowable starting material underlying the polymer layer 2, i.e., in particular, the acrylate or the acrylate mixture, and thus to produce and cure the polymer layer 2.

[0057] Furthermore, FIG. 1 shows an NIR laser 6 (infrared laser) with which NIR radiation 7 can be produced. The NIR laser 6 can be a USP (ultrashort pulse) laser.

[0058] With the aid of the infrared radiation 7 impinging on the polymer layer 2, cells 8 in the form of depressions can be created in the surface of the polymer layer 2, which are supposed to receive the actual printing ink in the subsequent gravure process.

[0059] The cells 8 can have different shapes and cross sections. For example, the inlet cross section of a cell can, e.g., be square, rectangular, diamond-shaped, triangular or circular. Other shapes are also possible. From this inlet cross section, the cell 8 extends into the depth or into the material, with different shapes being possible here as well.

[0060] In letterpress printing, the printing ink is accordingly not introduced into the cells 8 in the usual manner, but is applied to printing dots or surfaces left standing. During embossing, a relief is formed in the surface, which is then pressed into a carrier material.

[0061] The UV light source 4 and the NIR laser 6 are shown side by side in FIG. 1. However, they can be arranged in different apparatus or processing stations for logical reasons. In particular, a processing station can be provided for producing the polymer layer 2 on the base body 1. Subsequently, the print cylinder thus manufactured can be mechanically finished in an additional station, not shown, in order to smooth the surface of the polymer layer 2 and improve the roundness. Here, for example, a grinding process, turning, polishing, milling or turn-milling is suitable.

[0062] Only subsequently, in a “patterning” process step, the print cylinder can then be introduced into a station in which the NIR laser 6 is present in order to generate the cells 8 and thus the printing pattern (printing plate) in the surface of the polymer layer 2.

[0063] In addition, a marking field 9 is shown in the surface of the polymer layer 2. As explained above, it is possible to use lower-intensity infrared radiation to cause only a color change in the polymer layer 2 without laser ablation, i.e., a patterning of the surface. This makes it possible, for example, to produce the marking field 9, in which information such as a QR code or other codings can be stored.

[0064] Only when irradiated with higher-intensity infrared radiation 7, the actual cells 8 can be produced by laser ablation.

[0065] Various examples are given below for the production of the nanocomposite.

Example 1

[0066] 56 g Ebecryl 837, 14 g Sartomer SR 494, 1.75 g DYNASYLAN VTMO and a solution of 64 mg maleic acid in 0.64 g water are stirred in a 250 ml stirred vessel. Then, with continuous stirring, 5-40 m % Almal's nanopowder is added within 120 minutes and stirred for another 3 hours. After addition of 2.6 g DYNASYLAN VTMO and 5.2 g Iriotec 8210, the mixture must be stirred for another three hours.

Example 2

[0067] 23 g Ebecryl 1290, 46.4 g Sartomer SR 494, 12.5 g DYNASYLAN VTMO and a solution of 460 mg maleic acid in 4.6 g water are stirred in a 250 ml stirred vessel. Then, with continuous stirring, 5-40 m % Almal's nanopowder is added within 120 minutes and stirred for another 4 hours. After addition of 2.8 g DYNASYLAN VTMO and 5.6 g Iriotec 8210, the mixture must be stirred for another three hours.

Example 3

[0068] 56 g Ebecryl 837, 14 g Sartomer SR 494, 1.35 g DYNASYLAN VTMO and a solution of 48 mg maleic acid in 0.48 g water are stirred in a 250 ml stirred vessel. Then, with continuous stirring, 5-20 m % ZrO2 nanopowder is added within 120 minutes. Stirring continues for another 3 hours and then 3.0 g of Sartomer SR 297 is added to the mixture. After addition of 2.6 g DYNASYLAN VTMO and 5.2 g Iriotec 8210, the mixture must be stirred for another three hours.