Zero alcohol offset printing system

Abstract

This invention relates to a zero alcohol offset printing system, comprises the following parts: Plate cylinder (3), its outer cylindrical surface is covered by printing plate (4); Ink exertion system (1), which comprises ink source (8) and several inking rollers, to exert ink to the printing plate; Dampening liquid exertion system (2), which comprises dampening liquid source (7) and several dampening rollers, to exert dampening liquid to the printing plate; wherein the dampening rollers include a distributor roller (6); wherein the structure of the distributor roller (6) is as follows: it comprises a metal cylinder surrounded by a ceramic layer, and the ceramic layer has texture on its outer surface; wherein the content of alcohol or ether in the dampening liquid is zero.

Claims

1. A zero alcohol offset printing system, comprising the following parts: plate cylinder (3), its outer cylindrical surface covered by printing plate (4); ink depositing system (1), comprising ink source (8) and several inking rollers, to deposit ink to the printing plate; dampening liquid exertion system (2), comprising dampening liquid source (7) and several dampening rollers, to deposit dampening liquid to the mentioned printing plate; wherein the dampening rollers include a distributor roller (6); wherein: the structure of the distributor roller (6) comprises a metal cylinder surrounded by a ceramic layer on its outer surface wherein the ceramic layer is in direct contact with the metal cylinder, and the ceramic layer has texture on its outer surface; and, the content of alcohol or ether in the dampening liquid is zero.

2. The zero alcohol offset printing system according to claim 1, wherein the texture is a linear texture or a honeycomb shaped texture.

3. The zero alcohol offset printing system according to claim 2, wherein a thickness of the ceramic layer is 0.1-1.5 mm, a lines per inch (LPI) of the linear texture is 60-1500, and a depth of the linear pattern is 0.05-1 mm.

4. The zero alcohol offset printing system according to claim 2, wherein the thickness of the ceramic layer is 0.1-1.5 mm, the LPI of honeycomb shaped texture is 60-1500, and a depth of the honeycomb shaped texture is 0.05-1 mm.

5. The zero alcohol offset printing system according to claim 1, wherein there is no sandblasting layer between the metal cylinder and the ceramic layer of the distributor roller.

6. The zero alcohol offset printing system according to claim 1, wherein the alcohol is selected from ethanol, isopropyl alcohol, ethylene glycol, propylene glycol and glycerol.

7. The zero alcohol offset printing system according to claim 1, wherein the ether is propylene glycol methyl ether.

8. A zero alcohol offset printing method, comprising the following steps: a. Mounting a printing plate onto the outer cylindrical surface of a plate cylinder; b. Depositing dampening liquid by a dampening liquid depositing system to the printing plate to form a patterned dampening liquid film, the dampening liquid depositing system comprises a dampening liquid source and several dampening rollers, wherein the several dampening rollers include a distributor roller, which comprises a metal cylinder surrounded by a ceramic layer on its outer surface, thereby omitting the sandblasting layer, and the ceramic layer has texture on its outer surface; wherein the content of alcohol or ether in the dampening liquid is zero; c. Depositing ink by an ink depositing system to a non-patterned area on the printing plate which is not covered by the patterned dampening liquid film, the ink depositing system comprises an ink source and several inking rollers; d. Transforming the pattern on the printing plate to a blanket, and in turn transforming the pattern from the blanket to the printing paper or printing object, to complete printing process.

9. The zero alcohol offset printing method according to claim 8, wherein the thickness of the ceramic layer is 0.05-1.5 mm, and the texture is linear texture or honeycomb shaped texture, and the LPI of texture is 60-1500, and the depth of the texture is 0.05 to 1 mm.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic diagram of an offset printing system.

(2) FIG. 2 is a schematic view of a honeycomb shaped texture on the surface of the distributor roller.

(3) The reference numbers in the figures have the following meanings: (1) Ink exertion system; (2) Dampening liquid exertion system; (3) plate cylinder; (4) printing plate; (5) dampening form roller; (6) distributor roller; (7) dampening liquid source; (8) ink source.

EXAMPLES

(4) The present invention is further illustrated in conjunction with examples. The examples should not be construed as limiting the scope of the present invention.

Comparative Example 1

(5) An offset printing system shown in FIG. 1 is used. The system is the German Heidelberg CD102 model offset printing machine, all using their original ink exertion system and dampening liquid exertion system, including the distributor roller (6), the surface structure and shape characteristics of the distributor roller are as follows: metal roller blank, which comprises a metal cylinder and a sandblasting layer coating on its outer surface, said sandblasting layer having irregular texture on its outer surface. This system use commercially available dampening liquid which has an ethanol or isopropyl alcohol (IPA) content of 10%-25%, if the content is too low then printing cannot be operated. The adding amount of fountain solution is about 3.5%.

Comparative Example 2

(6) An offset printing system shown in FIG. 1 is used. The system is the German Heidelberg CD102 model offset printing machine, all using their original ink exertion system and dampening liquid exertion system, including the distributor roller (6), the surface structure and shape characteristics of the distributor roller are as follows: metal roller blank, which comprises a metal cylinder and a sandblasting layer coating on its outer surface, said sandblasting layer having irregular texture on its outer surface. The adding amount of fountain solution is about 3.5%, and the dampening liquid has an ethanol or isopropyl alcohol (IPA) content of less than 5%, i.e., the dampening liquid is the so-called alcohol free dampening liquid, It virtually uses alcohols or ethers as the ethanol or isopropyl substituting agent, so reduce the surface tension of water during printing, but at the same time, the erosion to the surface of the ink is also very serious, resulting in more printing problems, the cost is also increased a lot.

Example 1

(7) In this example the German Heidelberg CD102 model offset printing machine is also used, but the distributor roller (6) is as described in the present invention. The surface structure and shape characteristics of the distributor roller are as follows: metal roller blank, which comprises a metal cylinder and a ceramic layer covering on its outer surface, said ceramic layer having regular texture on its outer surface. After preparation of the ceramic layer to the metal roller, the ceramic layer can also be finely processed to improve its surface smoothness, and then be engraved by the laser electronic engraving technology to form the texture. There is no sandblasting layer between the metal cylinder and the ceramic layer of the distributor roller, i.e., the ceramic layer is direct contact with the metal cylinder. The ink layer is not eroded during printing, the printing performance is excellent, the printing problems can be better solved.

(8) The dampening liquid used in the present invention has an alcohol or ether content of 0%. The fountain solution is commercially available and contains no alcohol or ether, amount of about 3.5%. The adding amount of fountain solution is about 3.5%.

(9) The distributor roller (6) in the present invention is prepared by covering a ceramic layer with thickness 0.13 mm on the outer surface of a metal roller 5. The surface of the ceramic layer is engraved by the laser electronic engraving technology to form the honeycomb shaped texture, wherein the density of the honeycomb shaped texture is 1200 LPI, and the depth of the texture is 0.043 mm.

(10) Printing Effect Experiment

(11) Some well-recognized challenging printing tasks in the offset printing industry are used to evaluate the printing performance of the Comparative Example 1 and Example 1. The challenging printing task is the full solid printing on the hard cigarette wrapping paper whose surface is covered with aluminum foil. We printed 210,000 sheets. This product will be printed with six colors, and among the six colors, three colors are printed in full solid printing, two color are spot white ink printing, one color is dot gradation printing.

(12) The results are as follows:

(13) TABLE-US-00001 Alcohol or Content of isopropyl dampening Hue alcohol (IPA) liquid additive production Production rejection Dot Ink White ink comparative content solution (ten thousand/ quality rate repro- Process emulsification printing items (wt %) (wt %) sheets) (scrap) (%) Dryness duction downtime dirty float plain degree Comparative 12% 3.5% 4 5.2% 3.5% not normal 68 Serious good Example 1 good Comparative 2.3% 4.2% 3.1 8.9% 6.8 Not Not 7.9 Serious normal Example 2 good good Example 1 0 3.5% 4.1 3.8 1.2 Very better 66 no Very good good

(14) As can be seen from the experimental results of Comparative Example 1, Comparative Example 2 and Example 1, the offset printing system of the present invention can not only save cost, improve production efficiency and reduce scrap and process downtime, but also greatly improve the ink dryness, ink emulsification, floating dirty, white ink printing plain.

(15) As can be seen from the above results, the zero alcohol offset printing system of the present invention, use a dampening liquid exertion system which has specific surface features, even in the absence of ethanol or isopropyl alcohol in the dampening liquid, can also achieved the same or even superior printing results as compared with conventional offset printing system which use a dampening liquid containing ethanol or isopropyl alcohol.

(16) The foregoing is only preferred embodiments of the present invention, and is not intended to limit the present invention, any modifications, equivalent replacement and improvement made within the spirit and principles of the present invention, should be included in the protection scope of the present invention.