Etching solution and etching method

Abstract

This invention relates to the field of etching technology, and in particular to an etching solution and etching method. The etching solution of this invention comprises, by mass percentage: 5wt%–18wt% nitric acid, 2wt%–6wt% glacial acetic acid, 2wt%–5wt% white phosphorus, and 2wt%–8wt% iron oxide. The etching solution of this invention exhibits excellent etching ability and stability, improves the etching morphology, and reduces etching film thickness deviation. Using the etching solution of this invention to etch steel plates to obtain pad printing steel plates improves the flatness, smoothness, brightness, and gloss of the surface of the concave-plate printing images, ensures the matching degree of film thickness for large and small images, thereby increasing the service life of the pad printing and saving pad printing costs.

Description

Technical Field

[0001] This invention relates to the field of etching technology, specifically to an etching solution and etching method. Background Technology

[0002] In the etching process of pad printing steel plates, the main steps involved are cleaning the steel plate, applying photosensitive emulsion, drying, exposure, development, cleaning, etching, and depth measurement to form the recessed pad printing image. The recessed images on the steel plate are typically created using an etching solution. During the etching process, the etching solution chemically reacts with the image on the steel plate surface that is not covered by the photosensitive emulsion.

[0003] The following problems exist in using existing etching solutions to etch steel plates during the etching process: the etching morphology is poor, making it difficult to maintain the flatness, smoothness, and gloss of the surface of the intaglio printing image; the etching film thickness varies, the depth of the image differs, and the matching degree of film thickness for large and small images is poor; thus, it is difficult to meet the requirements of pad printing effect and stability.

[0004] In view of this, this invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide an etching solution that, by employing a combination of nitric acid, glacial acetic acid, white phosphorus, and iron oxide, improves the etching ability and stability of the etching solution, enhances the etching morphology and the smoothness of the uneven surface, and reduces the etching film thickness deviation.

[0006] The second objective of this invention is to provide an etching method that uses the etching solution described above to etch a steel plate to obtain a pad printing steel plate; this method improves the flatness, smoothness, brightness, and gloss of the surface of the concave pad printing image, ensures the matching degree of the film thickness of the large and small images, thereby improving the service life of pad printing and saving pad printing costs.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] This invention provides an etching solution, comprising the following components by mass percentage:

[0009] Nitric acid 5wt%–18wt%, glacial acetic acid 2wt%–6wt%, white phosphorus 2wt%–5wt%, and iron oxide 2wt%–8wt%.

[0010] Furthermore, the etching solution, by mass percentage, comprises the following components:

[0011] Nitric acid 10wt%–18wt%, glacial acetic acid 2wt%–6wt%, white phosphorus 2wt%–5wt%, iron oxide 2wt%–8wt%, with the balance being water.

[0012] Furthermore, the pH of the etching solution is 2 to 5.

[0013] The present invention also provides an etching method, which uses the etching solution described above to etch a steel plate to obtain a pad printing steel plate.

[0014] Furthermore, the etching method includes the following steps:

[0015] The etching solution is used to perform a first etching on the first and second images on the steel plate. After cleaning, the etching solution is used to perform a second etching on the second image after the first etching. After cleaning, the pad printing steel plate is obtained.

[0016] Furthermore, the steel plate includes at least one of high-quality steel plate, K460 imported steel plate, chromium steel plate, spring steel plate, and bearing steel plate.

[0017] Furthermore, the first etching time is 95–105 seconds.

[0018] Furthermore, the second etching time is 115–125 seconds.

[0019] Furthermore, the film thickness of the first image and the second image after the first etching is 2 to 12 μm.

[0020] Furthermore, the thickness of the second image after the second etching is 11–23 μm.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The etching solution of the present invention uses nitric acid, glacial acetic acid, white phosphorus and iron oxide in combination, which makes the etching solution have excellent etching ability and stability, improves the etching morphology and reduces the etching film thickness deviation.

[0023] The etching solution of this invention is used to etch steel plates to obtain pad printing steel plates, which improves the etching morphology of the images and the flatness, smoothness, brightness and gloss of the surface of the concave pad printing images, and ensures the matching degree of film thickness of large and small images, thereby improving the service life of pad printing and saving pad printing costs. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1This is the morphology of the recessed displacement print after etching in Embodiment 1 of the present invention.

[0026] Figure 2 This is the morphology of the recessed displacement print after etching in Comparative Example 1 of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope 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. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0028] The following is a detailed description of an etching solution and etching method according to an embodiment of the present invention.

[0029] In some embodiments of the present invention, an etching solution is provided, comprising the following components by mass percentage:

[0030] Nitric acid 5wt%–18wt%, glacial acetic acid 2wt%–6wt%, white phosphorus 2wt%–5wt%, and iron oxide 2wt%–8wt%.

[0031] The etching solution of this invention exhibits excellent etching ability and stability. The addition of white phosphorus alleviates the acidity of nitric acid; glacial acetic acid acts as a corrosion inhibitor, slowing down the etching process and thus improving the stability of the etching solution; furthermore, glacial acetic acid can adjust the pH value of the etching solution, maintaining it within an appropriate range to ensure the morphology of the etched text; iron oxide acts as an oxidizing agent for rust removal and polishing, thereby improving the smoothness (no residual metal), gloss, and shine of the etching.

[0032] In some embodiments of the present invention, the etching solution is a steel plate etching solution; preferably, the steel plate includes at least one of high-quality steel plate, K460 imported steel plate, chromium steel plate, spring steel plate and bearing steel plate.

[0033] When the etching solution of this invention is used to etch steel plates, the reaction products of white phosphorus during the etching process can alleviate the acidity of nitric acid; glacial acetic acid can form a thin film on the surface of the steel plate to prevent further etching, because glacial acetic acid contains CH3COO. -These ions combine with cations on the steel plate surface to form a protective oxide film. This oxide film slows down the etching process and prevents further oxidation, thus improving the stability of the etching solution. Simultaneously, glacial acetic acid adjusts the pH of the etching solution, maintaining it within an appropriate range, thereby enhancing its selective etching ability on the steel plate. This ensures the etching morphology of the graphics. Iron oxide (Fe2O3) can be used for oxidation, rust removal, and polishing of the recessed areas on the steel plate, making the recessed surfaces smoother, brighter, and improving their gloss.

[0034] In some embodiments of the present invention, typically but not limitingly, for example, the content of nitric acid in the etching solution may be a range of 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, or any combination thereof;

[0035] The content of glacial acetic acid in the etching solution can be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, or any combination thereof.

[0036] The content of white phosphorus in the etching solution can be 2wt%, 3wt%, 4wt%, 5wt%, or any combination thereof.

[0037] The iron oxide content in the etching solution can be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, or any combination thereof.

[0038] To achieve better etching results, the present invention further optimizes the content of each component in the etching solution.

[0039] In some embodiments of the present invention, the etching solution comprises, by mass percentage, the following components:

[0040] Nitric acid 10wt%–18wt%, glacial acetic acid 2wt%–6wt%, white phosphorus 2wt%–5wt%, iron oxide 2wt%–8wt%, with the balance being water.

[0041] Under the same etching time: a lower nitric acid content in the etching solution results in a shallower etched film thickness; a higher nitric acid content results in a deeper etched film thickness; a higher glacial acetic acid content leads to a slower etching rate and a reduced film thickness.

[0042] The etching solution of the present invention uses appropriate proportions of each component to achieve excellent etching effect, improve the stability of the etching solution, improve the morphology of the etched image, and make the surface smooth; and reduce the thickness deviation of the etched film.

[0043] In some embodiments of the invention, the pH of the etching solution is 2 to 5; typically, but not limitingly, for example, the pH of the etching solution can be a range of 2, 3, 4, 5 or any combination thereof.

[0044] The etching solution of the present invention has excellent etching ability when the pH is within the above range, especially improving the selective etching ability on pad printing steel plates.

[0045] In some embodiments of the present invention, an etching method is also provided, in which the above-mentioned etching solution is used to etch a steel plate to obtain a pad printing steel plate.

[0046] Using the etching solution of this invention to etch steel plates improves the morphology of concave-displacement printed images, as well as the surface flatness (no residual metal), smoothness, brightness, and gloss. It also ensures the matching degree of film thickness for large and small images, thereby improving the service life of pad printing and saving pad printing costs.

[0047] In some embodiments of the present invention, the etching method specifically includes the following steps:

[0048] The first and second images on the steel plate are first etched using an etching solution. After cleaning, the second image after the first etching is etched using the etching solution. After cleaning, the pad printing steel plate is obtained.

[0049] In the etching process of this invention, the patterns on the steel plate are classified into large patterns and small patterns; the first pattern is a small pattern, and the second pattern is a large pattern; during the etching process, the large and small patterns are etched together first, and then the large pattern is etched a second time. The large pattern is etched a second time to increase the film thickness, thus ensuring the matching of the film thickness between the large and small patterns.

[0050] In some embodiments of the present invention, the steel plate includes at least one of high-quality steel plate, K460 imported steel plate, chromium steel plate, spring steel plate and bearing steel plate.

[0051] The etching solution of this invention has excellent etching performance for recessed graphics on steel plates, which can produce good morphology of etched graphics, flat (without residual metal) and smooth and bright recessed surfaces, thereby reducing problems caused by the etching process; it ensures the matching of film thickness for large and small graphics, thereby increasing the life of pad printing steel plates, reducing manufacturing costs and improving the stability of pad printing.

[0052] In some embodiments of the present invention, the first etching time is 95 to 105 seconds; preferably, the first etching time is 100 seconds.

[0053] In some embodiments of the present invention, the second etching time is 105 to 115 seconds; preferably, the second etching time is 110 seconds.

[0054] In some embodiments of the present invention, the steel plate is a steel plate that has been developed and cleaned.

[0055] In some embodiments of the present invention, the etching method includes the following steps:

[0056] S1. Use tape to surround the large and small images (not covered by photosensitive emulsion) on the steel plate after development and cleaning;

[0057] S2. Add etching solution and use the etching solution to perform the first etching on the large and small graphics. Use a brush to clean the etched area. After the set time is reached, wash the steel plate with clean water.

[0058] S3. Use tape to cover and surround the edges of the small graphics; add etching solution and use the etching solution to perform a second etching on the large graphics; use a brush to clean the etched area of ​​the large graphics; after the set time is reached, wash the steel plate with clean water.

[0059] Before etching, the steel plate of the present invention undergoes the processes of coating with photosensitive emulsion, drying, exposure, development, and cleaning. The present invention does not impose strict limitations on the steel plate treatment process before etching; conventional pad printing steel plate preparation processes can be used.

[0060] The etching solution and etching method provided by the present invention will be described below with reference to specific embodiments.

[0061] Examples 1-15

[0062] Examples 1-15 provide an etching solution and an etching method for intaglio printing. The components and contents of the etching solutions in Examples 1-15 are shown in Table 1.

[0063] The etching methods for concave displacement printing images in Examples 1-15 include the following steps:

[0064] S1. Use tape to surround the large and small images (not covered by photosensitive emulsion) on the steel plate after development and cleaning;

[0065] S2. At room temperature, pour in the etching solution and use the etching solution to perform the first etching on the large and small graphics. Use a brush to clean the etching area. The first etching time is 100 seconds. Then wash the steel plate with clean water.

[0066] S3. Use tape to cover the small graphic and surround its edges; at room temperature, pour in etching solution and use the etching solution to perform a second etching on the large graphic. Use a brush to clean the area of ​​the large graphic. The second etching time is 110 seconds. Then wash the steel plate with clean water.

[0067] Table 1

[0068]

[0069]

[0070] Comparative Example 1

[0071] The etching solution provided in this comparative example consists of the following components by mass percentage:

[0072] Nitric acid 5 wt%, glacial acetic acid 2%, white phosphorus 2 wt%, balance water.

[0073] The etching method for the concave displacement printing pattern provided in this comparative example is based on Example 1.

[0074] Experimental Example 1

[0075] The morphology of the etched concave displacement imprints in Example 1 and Comparative Example 1 is as follows: Figure 1 and Figure 2 As shown.

[0076] from Figure 1 and Figure 2 As can be seen, the morphology of the etched concave displacement printing pattern in Example 1 has no residual metal, the surface is flat and glossy; while the concave displacement printing pattern in Comparative Example 1 has slight residual metal on the concave surface, is rough and uneven, and has no gloss.

[0077] The etching film thickness deviation, etching morphology, etching speed, and pad printing life of the etching methods of Examples 1-15 and Comparative Example 1 were tested respectively, and the results are shown in Table 2.

[0078] The method for testing the film thickness of a single image or text after etching is as follows: A film thickness gauge is used to measure the film thickness at two fixed points of a single image or text after the first or second etching.

[0079] Corrosion morphology: Examine the morphological features of the image and text under a 30x magnifying glass (whether the shape of the image and text is the same as the characters on the film; use a film thickness gauge to detect the film thickness deviation of the image and text).

[0080] Residual metal on recessed surfaces: Use a 30x magnifying glass to check for residual metal in the recessed areas of the characters, and whether the surface is rough or uneven.

[0081] Etching rate: V = H / T, where V is the etching rate, H is the film thickness, and T is the etching time.

[0082] The thickness of the second etching = the thickness of the second large-image test - the thickness of the first large-image test.

[0083] Table 2

[0084]

[0085]

[0086] As shown in Table 2, the etching solution of the present invention produces good etching morphology, with a film thickness of ±1 μm. Examples 1-4 show that a lower amount of nitric acid in the etching solution results in a shallower film thickness. In Examples 3-4, the amount of glacial acetic acid added to the etching solution was higher than in Examples 1-2, leading to a slower etching time and a lower film thickness than in Examples 1-2. In Examples 5-6, the amount of nitric acid in the etching solution was higher, resulting in a deeper film thickness than in Examples 1-4. In Examples 7-8, the amount of glacial acetic acid added to the etching solution was higher than in Examples 5-6, leading to a slower etching time. The film thickness in Examples 5-6 was lower than that in Examples 9-12; the amount of nitric acid in the etching solution gradually increased; the median mass ratio of acetic acid to white phosphorus was selected; the increase in nitric acid during the verification process reflected the increase in film thickness; the amount of nitric acid in the etching solutions of Examples 13-15 and 10-12 was the same, and the upper limit of the mass ratio of acetic acid to white phosphorus was selected; this caused the etching time to slow down, and the film thickness was lower than that in Examples 10-12; the etching methods of Examples 5-8 and Example 12 achieved the expected results; the matching degree of film thickness between large and small images was ensured; and the service life of pad printing was improved. In contrast, in Comparative Example 1, due to the lack of iron oxide, the etched image concave surface showed slight residual metal, was rough and uneven, and lacked gloss.

[0087] The pad printing steel plate (auxiliary material) was treated using the etching methods of concave pad printing images in Examples 5-8 and Example 12 to improve the performance of the pad printing steel plate. The usage of the pad printing steel plate before and after improvement is recorded in Tables 3 and 4.

[0088] Table 3

[0089]

[0090] As can be seen from Table 3, the annual steel plate cost saved by the etching method of the present invention is 896,000 yuan, which significantly reduces the cost of auxiliary materials.

[0091] Table 4

[0092]

[0093] As can be seen from Table 4, the original yield rate of pad printing steel plates was 99%. By adopting the etching method of the present invention, the yield rate was improved by 0.3%. Without improving the yield rate, a defect rate of 0.3% would require manual rework, and the product would need to be reprinted after rework. The present invention improves the yield rate by 0.3%, saving the cost of manual rework and reprinting, thereby significantly reducing labor costs.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A etching solution, characterized in that, By mass percentage, it includes the following components: Nitric acid 10wt%~18wt%, glacial acetic acid 2wt%~6wt%, white phosphorus 2wt%~5wt%, and iron oxide 2wt%~8wt%.

2. The etching solution according to claim 1, characterized in that, The pH of the etching solution is 2-5.

3. A method for etching, characterized in that, The steel plate is etched using the etching solution described in claim 1 or 2 to obtain a pad printing steel plate.

4. The etching method according to claim 3, characterized in that, Includes the following steps: The etching solution is used to perform a first etching on the first and second images on the steel plate. After cleaning, the etching solution is used to perform a second etching on the second image after the first etching. After cleaning, the pad printing steel plate is obtained.

5. The etching method according to claim 4, characterized in that, The first etching time is 95~105s.

6. The etching method according to claim 4, characterized in that, The second etching time is 115~125s.

7. The etching method according to claim 4, characterized in that, The film thickness of the first image after the first etching and the second image after the first etching are each independently 2~12μm.

8. The etching method according to claim 4, characterized in that, The thickness of the second image after the second etching is 11~25μm.

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