A method for manufacturing a flexographic plate

Abstract

The application provides a manufacturing method applied to a flexible plate mounting plate, and does not need to paste double-sided adhesive tape during mounting of the plate, greatly reduces printing quality problems caused by large thickness tolerance of the double-sided adhesive tape or bulging caused by plate pasting, and reduces environmental pollution. Industrial printing can accurately control the printing shape of the adhesive layer, and the adhesive layer firmly bonds the mounting plate base and the printing plate together through pressure, heating or light, is more resistant to bending, and can prevent the printing plate from falling off during long-term bending printing use.

Description

Technical Field

[0001] This invention belongs to the field of printing and relates to the operation process in flexographic printing, a necessary preparation step before printing, and in particular to a method for making a flexographic printing plate. Background Technology

[0002] As people's awareness of environmental protection gradually increases, environmental issues have become a hot topic in today's society. The printing industry, as an indispensable carrier of information in daily life, has attracted great attention. The printing industry has recognized the importance of environmental protection, and almost all printing companies hope to minimize environmental pollution, pay more attention to the health of their employees, and gradually shift towards an environmentally friendly model. The world is vigorously promoting the trend of green printing development, actively exploring ways to achieve industrial transformation and upgrading, and developing emerging green printing and packaging industries. As an environmental "model," flexographic printing, with its advantages of being environmentally friendly, easy to operate, fast printing speed, and widely applicable, has ushered in an unprecedented "golden" period of development.

[0003] Flexographic printing, a type of letterpress printing, is one of the main printing methods today. Because it uses environmentally friendly inks such as water-based inks, alcohol inks, and UV inks, it effectively reduces VOC emissions during the printing process. The ink layer contains almost no heavy metals, making it safe and healthy. Flexographic printing is commonly used in packaging printing, particularly suitable for packaging related to health and safety in daily chemicals, food, pharmaceuticals, and cosmetics. It is also used for special printing applications such as anti-counterfeiting, transfer printing, securities, and electronic components. Flexographic printing combines the characteristics of letterpress, gravure, and offset printing. Its rapid development is due to its simple printing process, low cost, wide application, high durability, and environmentally friendly printing method.

[0004] Flexographic printing is a printing method that uses a flexographic plate as the substrate. A flexographic plate is a photosensitive resin plate. The plates used for flexographic printing on the market include both solid and liquid plates, with solid plates (collectively referred to as flexographic plates) being the most common. It is estimated that the global annual consumption of flexographic plates exceeds 9 million square meters. Based on thickness, they can be divided into thick plates (3.94mm–7.00mm) and thin plates (1.14mm–2.84mm), with thick plates accounting for a larger proportion.

[0005] After the flexographic plate is made into a printing plate, it needs to be mounted before printing, which is mainly the case for thick plates. That is to say, before the flexographic plate is put into printing, the made printing plate needs to be glued to the double-sided film base to ensure that the printing plate will not detach from the printing roller during high-speed printing.

[0006] Currently, the most common method for bonding printing plate bases and printing plates in the market is using double-sided tape; no other bonding methods have been observed. However, double-sided tape bonding has certain drawbacks. It is highly dependent on the quality of the double-sided tape. Large thickness tolerances in the tape or air bubbles during application can affect the uniformity of ink transfer on the printing plate, leading to a decline in print quality. Furthermore, double-sided tape requires release paper for protection, increasing costs and increasing environmental pollution. Chinese patent CN114089603A introduces a new method: applying a layer of pressure-sensitive adhesive to the printing plate support base. During bonding, a thin film at the bottom is peeled off. Previously, a protective film was also required, and peeling off the film at the edges was not easy. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a method for manufacturing flexographic printing plates. This eliminates the need for double-sided tape during plate mounting, significantly reducing printing quality problems caused by large thickness tolerances of the double-sided tape or bulging during plate mounting, and also reducing environmental pollution. Furthermore, industrial printing allows for precise control of the adhesive layer's printing shape. The adhesive layer, through pressure, heating, or light exposure, firmly bonds the plate base and the printing plate together, making it more resistant to bending and preventing the printing plate from detaching during long-term bending and printing use.

[0008] The objective of this invention is achieved in the following manner: a method for manufacturing flexographic mounting plates, wherein an adhesive layer is precisely printed onto a mounting plate base using industrial printing, and then the mounting plate base and the printing plate are laminated together, and the finished mounting plate consists of a printing plate, an adhesive layer and a mounting plate base from top to bottom.

[0009] The adhesive layer can be any of the following: pressure-sensitive adhesive, thermosetting adhesive, or UV-curing adhesive.

[0010] After the adhesive layer is precisely printed onto the printing plate base using industrial printing methods, the adhesive layer is dried. Then, the printing plate base and the printing plate, which has undergone exposure, development, drying, and post-processing, are laminated together. Further processing completes the bonding between the printing plate base and the printing plate. The processing methods are as follows: for pressure-sensitive adhesives, pressure of 0.1-10 MPa is used for bonding; for thermosetting adhesives, activation is performed at 110-140℃; for photocurable adhesives, curing is performed by irradiation with UVA or UVC light for 5-300 seconds. This ensures the printing plate is firmly bonded to the printing plate base.

[0011] The adhesive layer is dried at a temperature of 60-110℃.

[0012] The thickness of the dried adhesive layer is 1-10 μm.

[0013] The specific steps for accurately printing the adhesive layer onto the printing plate substrate are as follows: set the flow rate, shape, and pattern density of the adhesive layer to be printed in the software control unit of the industrial printer; fill the prepared adhesive coating liquid into the storage tank; connect the storage tank to the print head through a circulation pipe; and when the printing plate substrate is transported or placed under the print head, the print head forms an angle of 10° to 90° with the printing plate substrate; and complete the industrial printing of the adhesive layer on the printing plate substrate according to the settings.

[0014] The substrate thickness of the printing plate base is 75-300μm, and the thickness of the printing plate is 1.0-7.0mm.

[0015] The adhesive layer is printed into one of the following shapes: linear, mesh, or dotted.

[0016] The substrate material of the mounting plate base is any one of polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP), and polyimide (PI), with polyethylene terephthalate (PET) film being preferred.

[0017] After processing, the flexographic plate is completed and can be directly mounted on the printing roller for printing.

[0018] Compared to existing technologies, this invention provides a method for manufacturing a flexible printing plate mounting system. This eliminates the need for double-sided tape during mounting, significantly reducing printing quality issues caused by large thickness tolerances of the double-sided tape or bulging during mounting, and also reducing environmental pollution. Furthermore, industrial printing allows for precise control of the adhesive layer's printing shape. The adhesive layer, through pressure, heating, or light exposure, firmly bonds the mounting plate base and the printing plate together, making it more resistant to bending and preventing the printing plate from detaching during long-term bending and printing use. The adhesive layer's bonding strength is measured based on the adhesive tape peel strength test method, using the BLD-200N electronic peel tester from Jinan Langguang Electromechanical Technology Co., Ltd., with a required adhesion strength of 2N / cm or higher. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the industrial printing adhesive layer in this invention, where the printing substrate is a plate base.

[0020] Figure 2 This is a completed printing plate sample that can be directly used for printing in this invention. From top to bottom, it consists of printing plate 1, adhesive layer 2, and printing plate base 3. Detailed Implementation

[0021] like Figure 1 and Figure 2As shown, a method for manufacturing a flexographic plate mounting plate involves using industrial printing to precisely print the adhesive layer 2 onto the mounting plate base 3, and then laminating the mounting plate base 3 and the printing plate 1 together. The finished mounting plate consists of the printing plate 1, the adhesive layer 2, and the mounting plate base 3 from top to bottom.

[0022] Adhesive layer 2 is any one of pressure-sensitive adhesive, thermosetting adhesive, or UV-curing adhesive.

[0023] After the adhesive layer 2 is precisely printed onto the printing plate base 3 using industrial printing, the adhesive layer 2 is dried. Then, the printing plate base 3 and the printing plate 1, which has undergone exposure, development, drying, and post-treatment, are laminated together. Further processing completes the bonding between the printing plate base 3 and the printing plate. The processing methods are as follows: for pressure-sensitive adhesives, pressure of 0.1-10 MPa is used for bonding; for thermosetting adhesives, activation is performed at 110-140℃; for photocurable adhesives, curing is performed by irradiation with UVA or UVC light for 5-300 seconds. This ensures the printing plate is firmly bonded to the printing plate base. The printing plate needs to be a pre-made flexographic plate, meaning a flexographic plate that can be directly used for printing after exposure, development, drying, and post-treatment. A flexographic plate that can be directly used for printing after exposure, development, drying, and post-treatment is a type of flexographic plate that can be directly used for printing in existing technologies.

[0024] The specific steps for accurately printing the adhesive layer onto the printing plate substrate are as follows: set the flow rate, shape, and pattern density of the adhesive layer to be printed in the software control unit of the industrial printer; fill the prepared adhesive coating liquid into the storage tank; connect the storage tank to the print head through a circulation pipe; and when the printing plate substrate is transported or placed under the print head, the print head forms an angle of 10° to 90° with the printing plate substrate; and complete the industrial printing of the adhesive layer on the printing plate substrate according to the settings.

[0025] For example, to print a 3μm thick, 75% density square coating, the flow rate of the adhesive layer to be printed is set in the software control unit of the industrial printer according to the thickness of the adhesive layer and the solid content of the adhesive coating liquid. The shape and pattern density are also set in the software control unit. The prepared adhesive coating liquid is loaded into the storage tank, which is connected to the print head through a circulation pipe. When the printing plate substrate is transported or placed under the print head, the print head forms an angle of 10°–90° with the printing plate substrate, such as 90°, 75° or 45°. The adhesive liquid enters the print head through the circulation pipe, and the adhesive layer is sprayed out and printed onto the printing plate substrate. After the industrial printing of the adhesive layer is completed, the printing plate substrate enters the next drying process. After drying, the finished printing plate substrate is obtained.

[0026] The method described in this application allows for precise control of the thickness of the printed adhesive layer, the shape and density of the graphics, and can also control multiple graphics coexistence, graphics density changes, and graphics overlay, which are applied to new flexographic plate mounting modes.

[0027] The current method of using double-sided tape for plate mounting is costly, polluting, and difficult to control in terms of peel force. Common industrial printing methods used in inkjet printing are relatively rough. The industrial printing method provided by this invention can precisely control both the coating thickness and the shape of the coating, such as mesh (dots, squares, rhombuses, and a combination of dots and lines), lines, and other graphic shapes or graphic layers. This facilitates control of peel force and saves costs.

[0028] The adhesive layer is dried at a temperature of 60-110℃.

[0029] The thickness of the dried adhesive layer is 1-10 μm.

[0030] The substrate thickness of the printing plate base is 75-300μm, and the thickness of the printing plate is 1.0-7.0mm.

[0031] The adhesive layer is printed into one of the following shapes: linear, mesh, or dotted.

[0032] The substrate material of the mounting plate base is any one of polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP), and polyimide (PI), with polyethylene terephthalate (PET) film being preferred.

[0033] After processing, the flexographic plate is completed and can be directly mounted on the printing roller for printing.

[0034] The present invention will now be described in detail with reference to specific embodiments. It should be noted that these embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above description of the present invention.

[0035] This invention provides a method for manufacturing flexographic printing plates. Specifically, an adhesive layer is precisely printed onto a printing plate substrate using industrial printing. After drying, the printing plate, which has undergone exposure, development, drying, and post-processing, is laminated onto the printing plate substrate with the adhesive layer. Depending on the type of adhesive layer, further processing such as pressure, heating, or light exposure is performed to firmly bond the printing plate to the printing plate substrate. The finished printing plate sample can be directly used for printing.

[0036] The substrate used for fabricating the flexible printing plate of this invention can be any one of polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP), and polyimide (PI), with polyethylene terephthalate (PET) film being preferred. The typical thickness is 75-300 μm.

[0037] The printing plate used in the production of the flexographic plate of this invention can be from any domestic or imported manufacturer. The printing plate can be either a polyester base or a metal base, and the thickness of the printing plate is 1.0-7.0 mm, with preferred printing plates having a polyester base of 3.94 mm or more.

[0038] The adhesive layer used in the flexible printing plate fabrication of this invention can be one of a pressure-sensitive adhesive, a thermosetting adhesive, or a UV-curable adhesive. The pressure-sensitive adhesive can be at least one of rubber-based, vinyl ether-based, silicone-based, or acrylate-based adhesives, with acrylate pressure-sensitive adhesives being preferred. The thermosetting adhesive can be at least one of phenolic and modified phenolic resins, epoxy resins, or polyurethanes, with modified phenolic resins being preferred. The UV-curable adhesive can be at least one of polyurethane-acrylate copolymers, polyurethane-vinyl acetate copolymers, polyurethane-vinyl ester / acrylate copolymers, etc., with polyurethane-acrylate copolymers being preferred.

[0039] The adhesive layer of this invention, used in the production of flexible printing plates, is printed onto the plate substrate using industrial printing methods. It can be precisely printed into one of the following shapes: linear, mesh, or dotted. After industrial printing, it requires drying at a temperature of 60-110℃, resulting in a thickness of 1-10 μm.

[0040] This invention discloses a method for fabricating a flexographic printing plate. After the adhesive layer dries, the plate base and printing plate are laminated together, followed by further processing. The pressure-sensitive adhesive can be applied at a pressure of 0.1-10 MPa; the thermosetting adhesive can be cured at a temperature of 110-140°C; and the photocurable adhesive can use a UVA or UVC light source with a curing time of 5-300 seconds. After this further processing, the flexographic printing plate is complete and ready for direct printing.

[0041] This invention employs a novel method for manufacturing flexographic printing plates, eliminating the need for double-sided tape during plate mounting. This significantly reduces printing quality issues caused by large thickness tolerances of double-sided tape or bulging during plate mounting, and also reduces environmental pollution. Furthermore, industrial printing allows for precise control of the adhesive layer's printing shape. The adhesive layer, through pressure, heating, or light exposure, firmly bonds the plate base and printing plate together, making it more resistant to bending and preventing detachment during long-term bending and printing use. The adhesive layer's bonding strength is measured using an adhesive tape peel strength tester (BLD-200N electronic peel tester from Jinan Langguang Electromechanical Technology Co., Ltd.), with a required adhesion strength of 2 N / cm or higher.

[0042] The following examples are intended to further illustrate the content of the present invention, but do not limit the scope of protection of the present invention.

[0043] Example 1

[0044] Plate preparation: R394-II (Lucky Huaguang). The plate-making process was completed following the back exposure - main exposure - development - drying - post-processing steps. Using a KMLS plate-making machine (Guangzhou Baiyun Kemao), the R394-II plate was exposed to the back for 60 seconds. The protective film on top of the plate was removed, and the prepared image film was placed on top. A vacuum of over 80% was applied, followed by a main exposure of 20 minutes. The exposed plate was then placed in a KEXH washer-dryer (Guangzhou Baiyun Kemao) for development using Shanghai Minchen environmentally friendly plate-washing solution for 8 minutes. After development, the plate was dried in an oven at 60℃ for 1.5 hours. After drying, the front of the plate was exposed for 5 minutes, followed by initial bonding for 5 minutes, and then post-processing. After all processes were completed, the plate-making was finished.

[0045] Preparation of the substrate: PET (125μm, Hefei Lucky), pressure-sensitive adhesive CF-55A (Weifang Fule New Materials). Prepare a 15% solids content pressure-sensitive adhesive coating solution in a storage tank. Using a Printer YD-F2513R5 sprayer (Shenzhen Yueda Color Printing), set the spray volume to 50g / ㎡, the print shape to a dot shape, the print density to 75%, and the print head to a 75° angle with the PET. Evenly spray the pressure-sensitive adhesive onto the PET. Dry at 80℃ for 10 minutes. The final coating thickness after drying is 10μm.

[0046] Plate making: Place the prepared printing plate and plate base together, apply 2 MPa pressure for 5 minutes to complete the plate making, and wait for printing.

[0047] Example 2

[0048] Printing plate preparation: Same as in Example 1.

[0049] Preparation of the substrate: PET (125μm, Hefei Lucky), thermosetting adhesive 0108 (Henan Gaimi New Materials). Prepare a 10% solids content thermosetting adhesive coating solution in a storage tank. Using a Printer YD-F2513R5 sprayer (Shenzhen Yueda Color Printing), set the spray volume to 22.5g / ㎡, the print shape to a square shape, the print density to 75%, and the print head to a 90° angle with the PET. Evenly spray the thermosetting adhesive onto the PET, dry at 90℃ for 3 minutes, and the final dried coating thickness is 3μm.

[0050] Plate making: Lay the prepared printing plate and plate base together, heat-activate at 140℃ for 5 minutes to complete the plate making, and wait for printing.

[0051] Example 3

[0052] Printing plate preparation: Same as in Example 1.

[0053] Preparation of the substrate: PET (125μm, Hefei Lucky), UV-curable adhesive BR394 (Lucky Huaguang). Prepare a 10% solids content UV-curable adhesive coating solution in a storage tank. Using a Printer YD-F2513R5 sprayer (Shenzhen Yueda Color Printing), set the spraying amount to 9g / ㎡, the print shape to a rhombus, the print density to 90%, and the print head to a 90° angle with the PET. Evenly spray the UV-curable adhesive onto the PET, dry at 90℃ for 3 minutes, and the final dried coating thickness is 1μm.

[0054] Plate making: The prepared printing plate and plate base are laminated together, and the KMLS exposure machine (Guangzhou Baiyun Kemao) uses a UV-A light source to irradiate for 20 seconds to complete the plate making, ready for printing.

[0055] Comparative Example 1

[0056] Printing plate preparation: Same as in Example 1. The prepared printing plate is the same as the printing plates in Examples 1-3.

[0057] Plate preparation: PET (125μm, Hefei Lucky Film).

[0058] Mounting plate preparation: The prepared printing plate is attached to the mounting plate base with double-sided tape (Yihong Adhesive Technology) to complete the mounting plate preparation, and it is ready for printing.

[0059] Based on the experimental method of adhesive tape peel strength, the prepared printing plate sample was cut into strips 20cm long and 2cm wide. The adhesion between the printing plate and the printing plate substrate was tested using a BLD-200S electronic peel tester (Jinan Langguang Electromechanical). The test conditions were a uniform peel speed of 200mm / min at 180°. The appearance after mounting was observed to check for bulges. The thickness tolerance of the prepared printing plate sample was tested using a CHY-C2 (Jinan Langguang Electromechanical). The results are shown in Table 1 below.

[0060] Table 1. Mounting conditions of the embodiments and comparative examples

[0061]

[0062] According to the requirements of this invention, the production of this flexible plate mounting plate does not require the application of double-sided tape during pre-press preparation. To ensure that the plate material does not peel off or fall off during printing, the adhesion between the plate mounting sheet base and the printing plate is required to be no less than 2N / cm.

[0063] As can be seen from Table 1 above, when using Examples 1, 2 and 3 of the present invention, the adhesion between the plate substrate and the printing plate reaches or exceeds the adhesion in Comparative Example 1 using double-sided tape. Furthermore, the appearance and thickness tolerance of the plate samples in Examples 1, 2 and 3 are better than those in Comparative Example 1, which can meet the printing requirements.

[0064] In addition to the methods for evaluating flexographic printing plate samples mentioned above, the following methods and standards can also be used for evaluation: The printing plate samples prepared in this invention are directly printed on the printing press, with more than 200,000 prints of printed cartons. During printing, it is observed whether the support body and the photosensitive layer separate, as well as the adhesion between the support body and the printing roller.

[0065] The flexible plate mounting method of this invention has shown good results after application.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. It should be noted that for those skilled in the art and any person skilled in the art, any equivalent substitutions or changes made to the technical solution and inventive concept of the present invention without departing from the overall concept of the present invention, as well as any changes and improvements made, should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing flexographic printing plates, characterized in that: The adhesive layer is printed onto the mounting plate base using industrial printing. Then, the mounting plate base and the printing plate are laminated together. The finished mounting plate consists of the printing plate, the adhesive layer, and the mounting plate base from top to bottom. The specific steps for accurately printing the adhesive layer onto the printing plate substrate are as follows: set the flow rate, shape, and pattern density of the adhesive layer to be printed in the software control unit of the industrial printer; fill the prepared adhesive coating liquid into the storage tank; connect the storage tank to the print head through a circulation pipe; and when the printing plate substrate is transported or placed under the print head, the print head forms an angle of 10° to 90° with the printing plate substrate; and complete the industrial printing of the adhesive layer on the printing plate substrate according to the settings.

2. The method for manufacturing a flexible printing plate according to claim 1, characterized in that: The adhesive layer can be any of the following: pressure-sensitive adhesive, thermosetting adhesive, or UV-curing adhesive.

3. The method for manufacturing a flexible plate hanging board according to claim 2, characterized in that: After the adhesive layer is precisely printed onto the printing plate base using industrial printing methods, the adhesive layer is dried. Then, the printing plate base and the printing plate, which has undergone exposure, development, drying, and post-processing, are laminated together. Further processing completes the bonding between the printing plate base and the printing plate. The processing methods are as follows: for pressure-sensitive adhesives, pressure of 0.1-10 MPa is used for bonding; for thermosetting adhesives, activation is performed at a temperature of 110-140℃; for photocurable adhesives, curing is performed by irradiation with a UVA or UVC light source for 5-300 seconds.

4. The method for manufacturing a flexible plate hanging board according to claim 3, characterized in that: The adhesive layer is dried at a temperature of 60-110℃.

5. The method for manufacturing a flexible printing plate according to claim 3, characterized in that: The thickness of the dried adhesive layer is 1-10 μm.

6. The method for manufacturing a flexible printing plate according to claim 1, characterized in that: The substrate thickness of the printing plate base is 75-300μm, and the thickness of the printing plate is 1.0-7.0mm.

7. The method for manufacturing a flexible printing plate according to claim 1, characterized in that: The adhesive layer is printed into one of the following shapes: linear, mesh, or dotted.

8. The method for manufacturing a flexible printing plate according to claim 1, characterized in that: The substrate material of the mounting plate is any one of polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, and polyimide.

9. The method of using the flexible printing plate according to any one of claims 1-8, characterized in that: After processing, the flexographic plate is completed and can be directly mounted on the printing roller for printing.

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