A method of intaglio printing of printed matter

Abstract

The present application provides a printing plate intaglio printing method, comprising: selecting a printing cylinder pad according to the intaglio printing plate graphics; designing and making a resin relief plate conforming to the shape profile of the intaglio printing plate graphics; installing the resin relief plate to a target position on the surface of the printing cylinder or in the printing cylinder pad, ensuring that the profile of the photosensitive resin layer on the resin relief plate accurately corresponds to the intaglio printing plate graphics; measuring the gap between the printing cylinder and the plate cylinder in the intaglio printing machine and the pad thickness of the printing cylinder pad, setting an initial printing pressure; transferring the corresponding color ink into the plate lines of the plate by an ink transfer device; performing a test printing of paper feeding, adjusting the initial printing pressure to a target printing pressure and the pad thickness of the printing cylinder pad; and batch printing to obtain a printing product with local intaglio printing effect. The present application solves the problem that the paper is easily deformed under high temperature and high pressure during intaglio printing, the surface smoothness increases, the ink is not easy to penetrate, and the printing quality is not high.

Description

Technical Field

[0001] This invention relates to the field of printing technology, and in particular to a gravure printing method for printed materials. Background Technology

[0002] In the printing industry, gravure printing produces products with a strong three-dimensional effect, rich layers, and excellent color expression, possessing good artistic appeal and anti-counterfeiting properties, making it particularly suitable for printing banknotes and exquisite anti-counterfeiting printed materials. A gravure printing press is a machine that uses an intaglio plate for printing. The image areas of the printing plate are recessed, while the blank areas are on the same plane as the outer circle of the printing cylinder. Gravure printing presses use a direct rotary printing method, utilizing the compression deformation of the elastic packing between the printing surfaces to obtain printing pressure and complete the printing task. The traditional printing principle of gravure printing is that the printing pressure between the printing cylinder and the impression cylinder forces the paper into close contact with the printing plate surface, transferring the ink from the gravure image to the paper, causing the ink to accumulate on the paper surface and forming a noticeable raised texture.

[0003] At present, the main way to achieve the gravure effect on the surface of printed matter is through gravure printing. The impression cylinder pad of the gravure printing machine is flatly covered on the cylinder surface. However, it has the following disadvantages: (1) The printing pressure applied by gravure printing is much greater than that of letterpress printing and offset printing. Since the main component of paper is natural fiber, the high temperature and high pressure used by the gravure printing machine during the printing process can easily cause the paper under pressure to deform. This often results in striped lines on the surface of the printed matter, i.e., wrinkles, which affects the appearance quality of the printed matter. (2) The high temperature and high pressure of gravure printing changes the surface characteristics and original texture of the entire printing surface of the paper. For example, the non-image part of the paper is directly in contact with the high temperature printing plate, which will increase the surface smoothness. The ink is not easy to penetrate, which affects the paper-ink bonding strength and printing effect after subsequent ink application. Therefore, the printing quality of letterpress printing still needs to be improved. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a gravure printing method for printed materials, which aims to solve the problem in the prior art that the paper is easily deformed under high temperature and high pressure during gravure printing, and the increased surface smoothness makes it difficult for ink to penetrate, resulting in poor printing quality.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for gravure printing of printed materials, characterized in that the method includes:

[0007] Step S10: Select an impression cylinder pad of suitable thickness according to the gravure image of the printed product. The impression cylinder pad includes an elastic pad paperboard, a resin letterpress, and a rubber blanket.

[0008] Step S20: Design and manufacture a resin relief plate that conforms to the shape and outline of the gravure image according to the gravure image pattern of the printed product.

[0009] Step S30: Install the prepared resin relief plate onto a target position on the surface of the impression cylinder or inside the impression cylinder liner to ensure that the outline of the photosensitive resin layer on the resin relief plate accurately corresponds to the intaglio image portion.

[0010] Step S40: Measure the gap between the impression cylinder and the printing plate cylinder in the gravure printing machine and the pad thickness of the impression cylinder liner, and set an initial printing pressure; the image area of ​​the printed product should have full imprints and clear lines, while the non-image area of ​​the printed product should be subjected to as little pressure as possible during the printing process.

[0011] Step S50: The ink of the corresponding color is transferred to the printing plate pattern through the ink transfer device.

[0012] Step S60: Perform paper feeding trial printing. Based on the gravure effect of the gravure image after printing, adjust the initial printing pressure to a target printing pressure and the pad thickness of the impression cylinder pad.

[0013] Step S70: Perform gravure printing in batches to obtain printed products with local gravure printing effect.

[0014] According to one aspect of the above technical solution, the elastic backing paperboard, the resin letterpress, and the rubber blanket are sequentially wrapped around the impression cylinder.

[0015] According to one aspect of the above technical solution, the resin relief plate includes a plate base, an adhesive layer, and a photosensitive resin layer, wherein the photosensitive resin layer is laid on the plate base through the adhesive layer.

[0016] According to one aspect of the above technical solution, the step of measuring the gap between the impression cylinder and the printing plate cylinder and the pad thickness of the impression cylinder liner in a gravure printing press, and setting an initial printing pressure, specifically includes:

[0017] Measure the gap between the working surfaces of the impression cylinder and the printing plate cylinder;

[0018] An initial thickness of the impression cylinder liner is provided based on the gap between the working surfaces of the impression cylinder and the printing plate cylinder, wherein the thickness of the impression cylinder liner is greater than the gap.

[0019] After adding an initial thickness of impression cylinder padding to the working surface of the impression cylinder, an initial printing pressure is generated between the impression cylinder and the printing plate cylinder.

[0020] According to one aspect of the above technical solution, after performing a paper feeding trial print, the method further includes:

[0021] Obtain the first surface image of the printed product after the trial printing.

[0022] The first surface image is subjected to histogram equalization to obtain the second surface image;

[0023] Based on the first surface image, extract several ink pixels and non-ink pixels from the first surface image, detect the depth of field of the ink pixels and non-ink pixels in the second surface image, and obtain the depth of field data of the ink pixels and the depth of field data of the non-ink pixels.

[0024] The depth of field of ink pixels in the ink pixel depth data is compared with the depth of field of non-ink pixels in the non-ink pixel depth data;

[0025] Determine whether the depth difference between the ink pixel and the non-ink pixel is within a preset depth threshold.

[0026] If not, adjust the pad thickness of the impression cylinder pad to adjust the initial printing pressure to the target printing pressure.

[0027] According to one aspect of the above technical solution, the step of adjusting the thickness of the impression pad of the impression cylinder to adjust the initial printing pressure to the target printing pressure specifically includes:

[0028] The thickness of the elastic backing paperboard in the printing cylinder pad is adjusted, either by increasing or decreasing the thickness of the elastic backing paperboard.

[0029] This adjusts the initial printing pressure to the target printing pressure.

[0030] According to one aspect of the above technical solution, the printed materials include banknotes, invoices, and business cards.

[0031] According to one aspect of the above technical solution, when printing the banknote product, the ink viscosity measured by a Hacker viscometer at 40°C is 5 Pa·s-15 Pa·s.

[0032] Compared with existing technologies, the gravure printing method for printed materials shown in this application has the following advantages:

[0033] By selecting an impression cylinder pad of suitable thickness according to the gravure image of the printed product, the impression cylinder pad includes a flexible backing paper, a resin letterpress, and the flexible backing paper. The resin letterpress is designed and manufactured according to the gravure image pattern of the printed product, and then installed onto the target position on the surface of the impression cylinder or within the impression cylinder pad. The lateral and vertical positions must be controlled to ensure that the photosensitive resin layer on the resin letterpress corresponds to the gravure image. The gap between the impression cylinder and the transfer cylinder, as well as the thickness of the impression cylinder pad, are measured. An initial printing pressure is set and ink is transferred for trial printing. Then, based on the printing effect of the gravure image in the printed product, it is determined whether the initial printing pressure needs to be adjusted. If so, it is adjusted to the target printing pressure. The impression cylinder and transfer cylinder are controlled to print the printed product according to the target printing pressure. The paper is not easily deformed, resulting in a printed product with a localized impression effect. Non-image areas are no longer affected by high temperature and high pressure, thus increasing surface smoothness. The ink can easily penetrate. Therefore, the gravure printing method for printed products shown in this invention can effectively improve the gravure printing quality of printed products. Attached Figure Description

[0034] Figure 1 This is a schematic flowchart of the gravure printing method for printed materials in the first embodiment of the present invention;

[0035] Figure 2 This is a side view of the resin relief plate in the first embodiment of the present invention.

[0036] Figure 3 This is a top view of the resin relief plate in the first embodiment of the present invention;

[0037] Figure 4 This is a partial flowchart of the gravure printing method for printed materials in the second embodiment of the present invention. Detailed Implementation

[0038] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0039] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] Example 1

[0042] Please see Figure 1 The first embodiment of the present invention provides a gravure printing method for printing on a substrate to obtain a printed product with a partial gravure effect. The paper surface of the printed product is not easily deformed, and the paper surface is not affected by the printing plate to increase the surface smoothness. The ink can effectively penetrate into the non-image areas, effectively increasing the degree of bonding between the ink and the paper.

[0043] Specifically, the gravure printing method for printed materials includes the following steps:

[0044] Step S10: Select an impression cylinder pad of suitable thickness according to the gravure image of the printed product. The impression cylinder pad includes an elastic pad paperboard, a resin letterpress, and a rubber blanket.

[0045] Among them, printed products such as banknotes, value-added tax invoices, and business cards have a certain textured surface, which can effectively prevent counterfeiting.

[0046] In practice, based on the gravure images of historical printed products, an impression cylinder pad of suitable thickness is selected. The impression cylinder pad includes an elastic pad paperboard, a resin letterpress, and an elastic pad paperboard. Specifically, the type and thickness of the resin letterpress suitable for the gravure images are selected to control the total thickness of the impression cylinder pad.

[0047] Step S20: Design and manufacture a resin relief plate that conforms to the shape and outline of the gravure image according to the gravure image pattern of the printed product.

[0048] Among them, the design and production of the resin relief plate in the printing cylinder pad specifically involves exposing the resin relief plate to make its shape and outline conform to the shape and outline of the intaglio images in historical printed products.

[0049] It should be noted that, as Figures 2-3As shown, the resin relief plate 10 includes a plate base 11, an adhesive layer 12, and a photosensitive resin layer 13. The photosensitive resin layer 13 is fixed to the plate base 11 through the adhesive layer 12. Therefore, controlling the thickness of the resin relief plate 10 is actually controlling the thickness of the photosensitive resin layer 13. By laying the photosensitive resin layer 13 on the adhesive layer 12 and then exposing the photosensitive resin layer 13, it conforms to the shape and outline of the gravure graphics in historical printed products.

[0050] Specifically, before being engraved, the photosensitive resin layer is set in a planar shape, laid on the adhesive layer, and fixed to the plate base by the adhesive layer. After the photosensitive resin layer is exposed and washed, some of the photosensitive resin material can be removed, while some of the photosensitive resin material is retained. Thus, the retained photosensitive resin material, the adhesive layer, and the plate base form a resin relief plate that corresponds to the gravure images in historical printed products.

[0051] Step S30: Install the prepared resin relief plate onto a target position on the surface of the impression cylinder or inside the impression cylinder liner, ensuring that the outline of the photosensitive resin layer on the resin relief plate accurately corresponds to the intaglio image portion.

[0052] In practice, the prepared resin relief plate needs to be installed on the surface of the impression cylinder or at a target position inside the impression cylinder liner. The horizontal and vertical positions of the resin relief plate on the impression cylinder surface or inside the impression cylinder liner must be controlled. Only when the resin relief plate is installed in the correct position can the effect corresponding to the gravure image in the historical printed product be produced.

[0053] Step S40: Measure the gap between the impression cylinder and the printing plate cylinder in the gravure printing machine and the pad thickness of the impression cylinder liner, and set an initial printing pressure; the image areas of the printed product should have full imprints and clear lines, while the non-image areas of the printed product should be subjected to as little pressure as possible during the printing process.

[0054] First, it should be noted that gravure printing presses use a pressure plate on the impression cylinder to contact the printing plate on the plate cylinder. The printed material passes between the pressure plate of the impression cylinder and the printing plate of the plate cylinder. During the rotation of the impression cylinder and the plate cylinder, the pressure plate and the printing plate come into contact with each other to achieve printing on the printed material when ink is applied.

[0055] Specifically, to achieve printing, it is necessary to control a suitable printing pressure. That is, the gap between the impression cylinder and the printing plate cylinder should be appropriate, neither too large nor too small. If the gap is too large, the lines of the printed image will be unclear, for example, the color will be too light. If the gap is too small, too much pressure will be applied to the printed material. When the printed material comes into contact with the printing plate, the surface of the printed material will become smooth, the material of the printed material will become compact, and the density will increase. This will make it difficult for the ink to penetrate, reduce the degree of adhesion between the ink and the printed material, and thus affect the printing quality.

[0056] Therefore, in this embodiment, an initial printing pressure needs to be set according to the gap between the impression cylinder and the printing plate cylinder and the thickness of the pressure cylinder pad. Under this initial printing pressure, the printed product is printed to obtain a test print sample.

[0057] In step S50, the ink of the corresponding color is transferred to the printing plate pattern through the ink transfer device.

[0058] The depth of the printing plate's embossed pattern can be set by those skilled in the art based on the gravure image of the printed product; the embossed pattern depth is typically 40µm-100µm. Additionally, the ink viscosity, measured by a Hacker viscometer at 40°C, is 5Pa·s-15Pa·s.

[0059] Step S60: Perform paper feeding trial printing. Based on the gravure printing effect of the gravure image after printing, adjust the initial printing pressure to a target printing pressure and the pad thickness of the impression cylinder pad.

[0060] The paper feeding trial printing requires inputting a batch of paper. Based on the gravure printing effect of these printed products, it is determined whether the gravure printing effect of the printed products obtained by the gravure printing machine under the current initial printing pressure meets the preset requirements.

[0061] If the lines in the gravure print are faint and the print is unclear, it indicates that the printing pressure of the gravure printing press is insufficient. The printing pressure of the gravure printing press needs to be increased. Specifically, the initial printing pressure used in the current trial print should be adjusted to a higher target printing pressure, and the padding thickness of the impression cylinder should be increased before another trial print is performed to obtain a print with a good gravure effect.

[0062] Conversely, if the lines in the gravure print become thicker and blurrier, the print becomes distorted, and the surface smoothness of the printed product is significantly improved, it indicates that the printing pressure of the gravure printing press is too high. The printing pressure of the gravure printing press needs to be reduced. Specifically, the initial printing pressure used in the current trial print is adjusted to a lower target printing pressure, and the padding thickness of the impression cylinder is reduced before another trial print is made to obtain a printed product with a good gravure effect.

[0063] Step S70: Perform gravure printing in batches to obtain printed products with local gravure printing effect.

[0064] Compared with existing technologies, the gravure printing method for printed materials shown in this embodiment has the following advantages:

[0065] By selecting an impression cylinder pad of suitable thickness according to the gravure image of the printed product, the impression cylinder pad includes a flexible backing paper, a resin letterpress, and the flexible backing paper. The resin letterpress is designed and manufactured according to the gravure image pattern of the printed product, and then installed onto the target position on the surface of the impression cylinder or within the impression cylinder pad. The lateral and vertical positions must be controlled to ensure that the photosensitive resin layer on the resin letterpress corresponds to the gravure image. The gap between the impression cylinder and the transfer cylinder, as well as the thickness of the impression cylinder pad, are measured. An initial printing pressure is set and ink is transferred for trial printing. Then, based on the printing effect of the gravure image in the printed product, it is determined whether the initial printing pressure needs to be adjusted. If so, it is adjusted to the target printing pressure. The impression cylinder and transfer cylinder are controlled to print the printed product according to the target printing pressure. The paper is not easily deformed, resulting in a printed product with a localized impression effect. Non-image areas are no longer affected by high temperature and high pressure, thus increasing surface smoothness. The ink can easily penetrate. Therefore, the gravure printing method for printed products shown in this invention can effectively improve the gravure printing quality of printed products.

[0066] Example 2

[0067] The second embodiment of the present invention provides a gravure printing method for printed materials. The gravure printing method for printed materials shown in this embodiment has basically the same steps as the gravure printing method for printed materials shown in the first embodiment, except that:

[0068] Please see Figure 4 In this embodiment, after the paper feeding test printing, the method further includes steps S61-S66:

[0069] Step S61: Obtain the first surface image of the printed product after trial printing.

[0070] Step S62: Perform histogram equalization on the first surface image to obtain the second surface image.

[0071] Step S63: Based on the first surface image, extract several ink pixels and non-ink pixels from the first surface image, detect the depth of field of the ink pixels and non-ink pixels in the second surface image, and obtain the depth of field data of the ink pixels and the depth of field data of the non-ink pixels.

[0072] Step S64: Compare the depth of field of ink pixels in the ink pixel depth data with the depth of field of non-ink pixels in the non-ink pixel depth data.

[0073] Step S65: Determine whether the depth difference between the ink pixel and the non-ink pixel is within a preset depth threshold.

[0074] If not, this embodiment proceeds to step S66 to adjust the printing pressure to obtain the target printing pressure for mass printing.

[0075] Step S66: Adjust the pad thickness of the impression cylinder pad to adjust the initial printing pressure to the target printing pressure.

[0076] Specifically, after the trial printing, in this embodiment, a first surface image of the printed product is acquired by a preset image acquisition device, such as a high-definition camera. After the first surface image is obtained by taking a picture of the printed product with the high-definition camera, the first surface image is input into the image processing system and subjected to histogram equalization processing to obtain a second surface image.

[0077] Specifically, after obtaining the first surface image and the second surface image after histogram equalization, the system automatically extracts several ink pixels and several non-ink pixels from the first surface image, detects the depth of field of the ink pixels in the first surface image in the second surface image to obtain ink pixel depth data, and detects the depth of field of the non-ink pixels in the first surface image in the second surface image to obtain non-ink pixel depth data.

[0078] It should be noted that the depth data of the ink pixel is the average depth data of several ink pixels. Similarly, the depth data of the non-ink pixel is the average depth data of several non-ink pixels. After obtaining the depth data of the ink pixel and the depth data of the non-ink pixel, the depth difference between the depth of the ink pixel and the depth of the non-ink pixel can be calculated, and it will be determined whether the depth difference is within a preset depth threshold.

[0079] If the depth difference is not within the preset depth threshold, it indicates that the pressure exerted by the gravure printing press on the printed product does not meet the printing requirements, and the printing pressure of the gravure printing press needs to be adjusted. Specifically, the thickness of the elastic padding paperboard in the impression cylinder padding is adjusted, increasing or decreasing the thickness of the padding paperboard to adjust the initial printing pressure to the target printing pressure.

[0080] In this embodiment, by analyzing the surface image of the printed product after trial printing and comparing the depth data of ink pixels and non-ink pixels, it is determined whether the printing pressure of the gravure printing machine meets the requirements, thus providing good data support for adjusting the printing pressure of the gravure printing machine.

[0081] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0082] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for gravure printing of printed materials, characterized in that, The method includes: Step S10: Select an impression cylinder pad of suitable thickness according to the gravure image of the printed product. The impression cylinder pad includes an elastic pad paperboard, a resin letterpress, and a rubber blanket. Step S20: Design and manufacture a resin relief plate that conforms to the shape and outline of the gravure image according to the gravure image pattern of the printed product. Step S30: Install the prepared resin relief plate onto a target position on the surface of the impression cylinder or inside the impression cylinder liner to ensure that the outline of the photosensitive resin layer on the resin relief plate accurately corresponds to the intaglio image portion. Step S40: Measure the gap between the impression cylinder and the printing plate cylinder in the gravure printing machine and the pad thickness of the impression cylinder liner, and set an initial printing pressure; the image area of ​​the printed product should have full imprints and clear lines, while the non-image area of ​​the printed product should be subjected to as little pressure as possible during the printing process. Step S50: The ink of the corresponding color is transferred to the printing plate pattern through the ink transfer device. Step S60: Perform paper feeding trial printing. Based on the gravure effect of the gravure image after printing, adjust the initial printing pressure to a target printing pressure and the pad thickness of the impression cylinder pad. Step S70: Perform gravure printing in batches to obtain printed products with local gravure printing effect.

2. The gravure printing method for printed materials according to claim 1, characterized in that, The elastic backing paperboard, resin letterpress, and rubber sheet are sequentially wrapped around the impression cylinder.

3. The gravure printing method for printed materials according to claim 2, characterized in that, The resin relief plate includes a plate base, an adhesive layer, and a photosensitive resin layer, wherein the photosensitive resin layer is laid on the plate base through the adhesive layer.

4. The gravure printing method for printed materials according to claim 1, characterized in that, The steps for measuring the gap between the impression cylinder and the plate cylinder in a gravure printing press, and the thickness of the impression cylinder liner, and setting an initial printing pressure, specifically include: Measure the gap between the working surfaces of the impression cylinder and the printing plate cylinder; An initial thickness of the impression cylinder liner is provided based on the gap between the working surfaces of the impression cylinder and the printing plate cylinder, wherein the thickness of the impression cylinder liner is greater than the gap. After adding an initial thickness of impression cylinder liner to the working surface of the impression cylinder, an initial printing pressure is generated between the impression cylinder and the printing plate cylinder.

5. The gravure printing method for printed materials according to claim 4, characterized in that, After the paper feeding test print, the method further includes: Obtain the first surface image of the printed product after the trial printing. The first surface image is subjected to histogram equalization to obtain the second surface image; Based on the first surface image, extract several ink pixels and non-ink pixels from the first surface image, detect the depth of field of the ink pixels and non-ink pixels in the second surface image, and obtain the depth of field data of the ink pixels and the depth of field data of the non-ink pixels. The depth of field of ink pixels in the ink pixel depth data is compared with the depth of field of non-ink pixels in the non-ink pixel depth data; Determine whether the depth difference between the ink pixel and the non-ink pixel is within a preset depth threshold. If not, adjust the pad thickness of the impression cylinder pad to adjust the initial printing pressure to the target printing pressure.

6. The gravure printing method for printed materials according to claim 5, characterized in that, The step of adjusting the pad thickness of the impression cylinder pad to adjust the initial printing pressure to the target printing pressure specifically includes: The thickness of the elastic backing paperboard in the printing cylinder pad is adjusted, either by increasing or decreasing the thickness of the elastic backing paperboard. This adjusts the initial printing pressure to the target printing pressure.

7. The gravure printing method for printed materials according to any one of claims 1-6, characterized in that, The printed materials include banknotes, invoices, and business cards.

8. The gravure printing method for printed materials according to claim 7, characterized in that, When printing the banknotes, the ink viscosity, measured by a Hacker viscometer, is 5 Pa·s to 15 Pa·s at 40°C.

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