Image-providing printing forme, and method for producing a printing forme

Abstract

An imaging printing form having a base body with an elastomeric coating, in which the elastomeric coating carries an engraving pattern. The elastomeric coating has a hard rubber with a hardness of greater than 40 Shore D, and more particularly greater than 70 Shore D. The hard rubber is based on butadiene-acrylonitrile rubber (NBR), carboxyl group-containing nitrile rubber (XNBR), hydrogenated acrylonitrile butadiene Rubber (HNBR) or combinations thereof.

Claims

1. A process for the production of an image-providing printing template, the process comprising: a. the provision of a base; b. the provision of an elastomer coating on the base; and, c. the provision of an engraved pattern on the elastomer coating by engraving; wherein the elastomer coating comprises a hard rubber and has a hardness above 70 Shore D according to DIN ISO 7619-1, and wherein the hard rubber is based on butadiene-acrylonitrile rubber (NBR), carboxyl group-containing nitrile rubber (XNBR), hydrogenated acrylonitrile butadiene Rubber (HNBR) or combinations thereof, wherein the elastomeric coating is formed from a calendered sheet that is wound around the base, and the elastomeric coating is vulcanized by bandaging the elastomeric layer after it is applied to the base and then heating in an autoclave.

2. The process as claimed in claim 1, wherein the step b. of the provision of an elastomer coating on the base comprises the following steps: b.1 covering of the base with an elastomer or an elastomer mixture; b.2 vulcanization of the elastomer or the elastomer mixture with formation of the hard rubber; b.3 removal of excess hard rubber by a turning procedure; and, b.4 removal of material by grinding from the surface of the elastomer coating.

3. The process as claimed in claim 1, wherein the engraving is achieved by an electromechanical engraving procedure which produces cells with a depth of from 45 m to 55 m.

4. The process as claimed in claim 1, wherein the engraving is achieved by a laser engraving procedure.

5. The process as claimed in claim 1, wherein the image-providing printing template is in the form of a gravure cylinder.

6. The process as claimed in claim 1, wherein the image-providing printing template is in the form of a printing plate.

7. The process as claimed in claim 1, wherein the base body is a hollow cylinder.

8. The process as claimed in claim 1, wherein the base body is an axle cylinder.

9. The process as claimed in claim 1, wherein the base body is a sleeve as a cylindrical strength support.

10. The process as claimed in claim 1, wherein the elastomer coating has a thickness of at least 30 microns.

11. The process as claimed in claim 1, wherein a surface of the elastomer coating has an average roughness depth of less than 1 m Rz.

12. The process as claimed in claim 1, wherein the hard rubber is based on butadiene-acrylonitrile rubber (NBR).

13. The process as claimed in claim 1, wherein the hard rubber is based on carboxyl group-containing nitrile rubber (XNBR).

14. The process as claimed in claim 1, wherein the hard rubber is based on hydrogenated acrylonitrile butadiene rubber (HNBR).

15. The process as claimed in claim 1, wherein the hard rubber is based on a combination of butadiene-acrylonitrile rubber (NBR), carboxyl group-containing nitrile rubber (XNBR), and hydrogenated acrylonitrile butadiene rubber (HNBR).

16. The process as claimed in claim 1, wherein the engraving is achieved by a laser engraving procedure which produces cells with a depth of from 35 m to 45 m.

17. The process as claimed in claim 1, wherein the rubber has a hardness from above 70 Shore D to 82 Shore D.

18. The process of claim 1, wherein: the base body is a hollow cylinder, the elastomer coating on the base is a single layer having a thickness from 30 micrometers to 30 millimeters, and a roughness of the elastomeric coating is less than 2 micrometers Rz.

Description

EXAMPLE

(1) A black-color HNBR mixture with the following properties was produced: Color: CA.9005 RAL Hardness: 77D Shore A Density: 1.245 g/cm.sup.3

(2) The unvulcanized rubber mixture was provided in homogeneous form as drawn calendered sheet with thickness about 1.2 mm, and wound around a hollow aluminum cylinder. The unvulcanized rubber exhibited very little stickiness, and therefore could be wound successfully.

(3) Vulcanization was then carried out at a temperature of 135 C. for a period of 16 hours. The material was then cooled slowly, in order to avoid separation effects.

(4) A lathe cutter was then used for turning to an unfinished dimension of 143.39 mm. The advance rate here was restricted to 50 mm/min, and the surface temperature was monitored to ensure that this was in a range of 40 to 50 degrees Celsius.

(5) The elastomer-coated hollow aluminum cylinder was then polished. This was achieved in two steps of fine polish to a final dimension of 143.24 mm. The average roughness depth Rz of the surface after the fine polish was below 0.6 m.

(6) The surface was then ground in order to adjust the average roughness depth Rz of the surface to 0.7 to provide the lubricating ink layer under the doctor blade.

(7) The hardness of the elastomer coating was 82 Shore D.

(8) A 120 diamond stylus was then used for electromechanical engraving. Stylus wear was continuously monitored here.

(9) FIG. 1 shows a micrograph of the engraved surface. The quality of the cut outlines/cell edges corresponded to that of a conventional printing template with copper coating.

(10) The intaglio printing cylinder thus produced was used in an intaglio printing test.

(11) FIG. 2 shows a micrograph of the resultant print.

(12) The ink density of the resultant print was 1.7. Toning and area coverage were satisfactory.

(13) Finally, a wear test was carried out by printing with a Moser proofing press with soft MDC blade. The quality of the print was satisfactory up to 150 000 running meters. The requirement is only 50 000 running meters. The intaglio printing cylinder therefore exhibited low wear.

(14) In summary, the hard-rubber-coated intaglio printing cylinder exhibited printing results just as good as those from a conventional copper-coated and hard-chromium-plated intaglio printing cylinder.