A method for measuring copper-chromium grayscale loss in gravure printing

Abstract

This invention relates to a method for measuring copper-chromium grayscale loss in gravure printing, comprising: plating copper on the surface of a roller to obtain a copper roller; engraving a multi-level grayscale scale pattern on the surface of the copper roller; printing the multi-level grayscale scale pattern onto the surface of a substrate using the copper roller to obtain a first printed grayscale scale pattern; measuring the amount of ink printed by the copper roller for each grayscale level in the first printed grayscale scale pattern; plating chromium on the surface of the copper roller to obtain a chromium roller; printing the multi-level grayscale scale pattern onto the surface of the substrate using the chromium roller to obtain a second printed grayscale scale pattern; measuring the amount of ink printed by the chromium roller for each grayscale level in the second printed grayscale scale pattern; calculating the ink printing loss rate of each grayscale level when the copper roller and chromium roller print the same pattern, and obtaining the grayscale loss value for each grayscale level. The grayscale loss value obtained by this invention can be directly applied to the pattern to be printed when manufacturing rollers for formal production, improving production efficiency, reducing costs, and ensuring printing quality.

Description

Technical Field

[0001] This invention belongs to the field of gravure printing technology, specifically relating to a method for measuring copper-chromium grayscale loss in gravure printing. Background Technology

[0002] Gravure printing is a direct printing technique with advantages such as stable print quality and high printing speed. Gravure printing directly transfers the ink contained in the recesses of a gravure printing plate onto the surface of the substrate. The tonal range of the printed image is determined by the size and depth of the recesses. Deeper recesses contain more ink, resulting in a thicker ink layer on the substrate; shallower recesses contain less ink, resulting in a thinner ink layer. Currently, in gravure printing, recesses corresponding to the image to be printed are typically engraved on a roller. During printing, ink is filled into the recesses, and the ink on the roller surface is scraped off with a doctor blade. The roller and substrate come into contact under pressure, transferring the ink from the recesses to the substrate, thus completing the printing process.

[0003] The printing roller is a crucial component in gravure printing, and its quality directly impacts the overall printing quality. In existing technology, the roller manufacturing process involves: first, copper plating is applied to the surface of a steel pipe to form a copper layer; then, patterns are engraved onto the copper layer to form dots. The copper layer has a fine crystal structure, a bright and smooth surface, uniform thickness, low hardness, and good dot formation, facilitating pattern engraving. Finally, a chromium plating process is used to form a chromium layer on the copper surface, increasing the roller's surface hardness and wear resistance, preventing the doctor blade from scratching the copper layer during printing and thus preserving the printing effect. However, after chromium plating, the chromium layer adheres to the surface of the copper layer, forming a thin chromium film. This film can also fill within the dots of the copper layer, causing variations in depth and resulting in grayscale loss. This leads to deviations in the depth of the printed pattern from the expected value, affecting the quality of gravure printing. Therefore, before formal printing, numerous sample rollers need to be repeatedly manufactured for adjustment to ensure acceptable printing results, increasing costs and reducing production efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a method for measuring copper-chromium grayscale loss in gravure printing.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for measuring copper-chromium grayscale loss in gravure printing includes:

[0007] S1: A copper layer is formed on the surface of the roller through a copper plating process to obtain a copper roller. A multi-level gray scale pattern is engraved on the surface of the copper roller. The multi-level gray scale pattern is printed on the surface of the substrate using the copper roller to obtain the first printed gray scale pattern.

[0008] S2: Measure the amount of copper roller printing ink for each gray level in the first printed gray scale pattern;

[0009] S3: Clean the surface of the copper roller and form a chromium layer on the surface of the copper roller through a chromium plating process to obtain a chromium roller. Use the chromium roller to print a multi-level grayscale ladder pattern on the surface of the substrate to obtain a second printed grayscale ladder pattern.

[0010] S4: Measure the amount of chrome roller printing ink for each gray level in the second gray scale pattern.

[0011] S5: Calculate the ink printing loss rate of each gray level when printing the same pattern with copper rollers and chrome rollers based on the ink volume of copper rollers and chrome rollers for each gray level, and obtain the gray level loss value for each gray level.

[0012] Preferably, in S1, the total number of gray levels in the multi-level grayscale ladder pattern is N, and the grayscale value of each gray level is K. n ,

[0013]

[0014] Where: n = 1, 2, ..., N.

[0015] More preferably, the total number of orders N in the multi-level grayscale step pattern is 10 to 25.

[0016] More preferably, the total number of orders N in the multi-level grayscale step pattern is 20.

[0017] More preferably, in S5, the ink printing loss rate φ for each gray level is... n for:

[0018]

[0019] in:

[0020] H 1n This refers to the amount of ink printed on the copper roller for each gray level in the first grayscale gradient pattern.

[0021] H 2n The amount of chrome roller printing ink for each gray level in the second gray scale pattern.

[0022] More preferably, in S5, the grayscale loss value L for each grayscale level is... n for:

[0023] L n =K n ×φ n .

[0024] Preferably, the measurement method further includes:

[0025] S6: When making the rollers for formal production, the grayscale loss value is loaded onto the pattern to be printed, and then it is engraved onto the surface of the copper roller.

[0026] Preferably, in S1, a multi-level grayscale step pattern is prepared using Photoshop software.

[0027] Preferably, in S2, NeoStampa software is used to measure the amount of copper roller printing ink for each gray level in the first printed gray scale pattern; in S4, NeoStampa software is used to measure the amount of chrome roller printing ink for each gray level in the second printed gray scale pattern.

[0028] Preferably, in S1, electronic engraving or laser engraving is used when engraving multi-level grayscale ladder patterns on the surface of the copper roller.

[0029] Preferably, in S1, the thickness of the copper layer is 0.12 to 0.15 mm; in S3, the thickness of the chromium layer is 0.01 to 0.015 mm.

[0030] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0031] The measurement method of this invention can obtain the grayscale loss value of each grayscale level when printing the same pattern with copper and chromium rollers. When making the rollers for formal production, the grayscale loss value can be directly applied to the pattern to be printed, without the need to repeatedly make a large number of sample rollers for adjustment, saving time, improving production efficiency, reducing costs, and ensuring printing effect. The process is simple, easy to operate, and has good practicality. Attached Figure Description

[0032] Appendix Figure 1 This is a flowchart of the copper-chromium grayscale loss measurement method of the present invention;

[0033] Appendix Figure 2 This is a schematic diagram of the multi-level grayscale ladder pattern of the present invention. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] A method for measuring copper-chromium grayscale loss in gravure printing, such as Figure 1 As shown, it includes:

[0037] S1: A copper layer is formed on the surface of the roller through a copper plating process to obtain a copper roller. A multi-level grayscale ladder pattern is engraved on the surface of the copper roller. The multi-level grayscale ladder pattern is printed onto the surface of the substrate using the copper roller to obtain the first printed grayscale ladder pattern. Specifically:

[0038] (1) A copper layer is formed on the surface of the roller by a copper plating process. The roller can be made of seamless steel pipe. The thickness of the copper layer is 0.12 to 0.15 mm, and finally a copper roller is obtained.

[0039] (2) Prepare a multi-level grayscale ruler pattern using Photoshop software. The total number of grayscale levels in the multi-level grayscale ruler pattern is N, and the grayscale value of each grayscale level is K. n K n The calculation formula is:

[0040]

[0041] Where: n = 1, 2, ..., N;

[0042] The total number of grayscale step pattern N is preferably 10 to 25.

[0043] (3) Use electronic engraving or laser engraving technology to engrave multi-level grayscale ladder pattern on the surface of copper roller;

[0044] (4) A multi-level grayscale ruler pattern is printed on the surface of the substrate using a copper roller to obtain the first printed grayscale ruler pattern.

[0045] S2: Measure the amount of ink printed on the copper roller for each gray level in the first printed grayscale scale pattern. Specifically, use NeoStampa software to measure and obtain the amount of ink printed on the copper roller H for each gray level in the first printed grayscale scale pattern. 1n .

[0046] S3: The surface of the copper roller is cleaned, and a chromium layer is formed on the surface of the copper roller through a chromium plating process to obtain a chromium roller. The multi-level grayscale ladder pattern is printed on the surface of the substrate using the chromium roller to obtain the second printed grayscale ladder pattern. Specifically:

[0047] (1) Clean the surface of the copper roller and then form a chromium layer on the surface of the copper roller by a wet chromium plating process. The thickness of the chromium layer is 0.01 to 0.015 mm, and finally a chromium roller is obtained.

[0048] (2) A multi-level grayscale ladder pattern is printed on the surface of the substrate using a chromium roller to obtain a second printed grayscale ladder pattern.

[0049] S4: Measure the amount of chrome roller printing ink for each gray level in the second printed grayscale scale pattern. Specifically, use NeoStampa software to measure and obtain the amount of chrome roller printing ink H for each gray level in the second printed grayscale scale pattern. 2n .

[0050] S5: The amount of ink H printed on the copper roller for each gray level. 1n Ink volume H for chrome roller printing 2n Calculate the ink printing loss rate φ for each gray level when printing the same pattern using copper and chrome rollers. n The grayscale loss value L for each gray level is obtained. n Specifically:

[0051] Ink printing loss rate φ for each gray level n for:

[0052]

[0053] Gray loss value L for each gray level n for:

[0054] L n =K n ×φ n .

[0055] S6: When making the rollers for formal production, the grayscale loss value is loaded onto the pattern to be printed, and then engraved onto the surface of the copper roller to compensate for the grayscale loss of the pattern after chrome plating.

[0056] Example

[0057] A method for measuring copper-chromium grayscale loss in gravure printing includes:

[0058] S1: A copper layer is formed on the surface of the roller through a copper plating process to obtain a copper roller; a multi-level grayscale ruler pattern is prepared using Photoshop software, with a total of 20 levels in the pattern. Figure 2 As shown, the gray value K for each gray level is...n As shown in Table 1, that is, K1 = 0, K2 = 5, ..., K 20 =95; A multi-level grayscale ladder pattern is engraved on the surface of a copper roller using laser engraving technology; The multi-level grayscale ladder pattern is printed onto the surface of a substrate using a copper roller to obtain the first printed grayscale ladder pattern.

[0059] S2: The amount of ink printed on the copper roller for each gray level in the first printed grayscale scale pattern was measured using NeoStampa software. 1n As shown in Table 1.

[0060] S3: Clean the surface of the copper roller and form a chromium layer on the surface of the copper roller through a chromium plating process to obtain a chromium roller; use the chromium roller to print a multi-level grayscale ladder pattern on the surface of the substrate to obtain a second printed grayscale ladder pattern.

[0061] S4: The amount of chrome roller printing ink H for each gray level in the second gray scale pattern was measured using NeoStampa software. 2n As shown in Table 1.

[0062] S5: The amount of ink H printed on the copper roller for each gray level. 1n Ink volume H for chrome roller printing 2n Calculate the ink printing loss rate φ for each gray level when printing the same pattern using copper and chrome rollers. n As shown in Table 1; then the grayscale loss value L for each grayscale level is calculated. n As shown in Table 1.

[0063] S6: When manufacturing the rollers for production, apply the grayscale loss value L for each grayscale level to the pattern to be printed. n Then, it is engraved onto the surface of the copper roller to compensate for the loss of grayscale in the pattern after chrome plating.

[0064] Table 1

[0065]

[0066] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for measuring copper-chromium grayscale loss in gravure printing, characterized in that: include: S1: A copper layer is formed on the surface of the roller through a copper plating process to obtain a copper roller. A multi-level gray scale pattern is engraved on the surface of the copper roller. The multi-level gray scale pattern is printed on the surface of the substrate using the copper roller to obtain the first printed gray scale pattern. S2: Measure the amount of copper roller printing ink for each gray level in the first printed gray scale pattern; S3: Clean the surface of the copper roller and form a chromium layer on the surface of the copper roller through a chromium plating process to obtain a chromium roller. Use the chromium roller to print a multi-level grayscale ladder pattern on the surface of the substrate to obtain a second printed grayscale ladder pattern. S4: Measure the amount of chrome roller printing ink for each gray level in the second gray scale pattern. S5: Calculate the ink printing loss rate of each gray level when printing the same pattern with copper rollers and chrome rollers based on the ink volume of copper rollers and chrome rollers for each gray level, and obtain the gray level loss value for each gray level.

2. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 1, characterized in that: In S1, the total number of gray levels in the multi-level grayscale ruler pattern is N, and the grayscale value of each gray level is K. n , Where: n = 1, 2, ..., N.

3. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 2, characterized in that: The total number of orders N for multi-level grayscale step pattern is 10 to 25.

4. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 2, characterized in that: In S5, the ink printing loss rate φ for each gray level n for: in: H 1n This refers to the amount of ink printed on the copper roller for each gray level in the first grayscale gradient pattern. H 2n The amount of chrome roller printing ink for each gray level in the second gray scale pattern.

5. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 4, characterized in that: In S5, the grayscale loss value L for each grayscale level n for: L n =K n ×φ n 。 6. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 1, characterized in that: The measurement method further includes: S6: When making the rollers for formal production, the grayscale loss value is loaded onto the pattern to be printed, and then it is engraved onto the surface of the copper roller.

7. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 1, characterized in that: In S1, Photoshop software is used to prepare multi-level grayscale step ruler patterns.

8. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 1, characterized in that: In S2, NeoStampa software is used to measure the amount of copper roller printing ink for each gray level in the first printed gray scale pattern. In S4, NeoStampa software is used to measure the amount of chrome roller printing ink for each gray level in the second printed gray scale pattern.

9. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 1, characterized in that: In S1, electronic engraving or laser engraving is used when engraving multi-level grayscale scale patterns on the surface of the copper roller.

10. The method for measuring copper-chromium grayscale loss in gravure printing according to claim 1, characterized in that: In S1, the thickness of the copper layer is 0.12–0.15 mm; in S3, the thickness of the chromium layer is 0.01–0.015 mm.

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