An acid and alkali resistant high-strength composite printing nickel screen and preparation method thereof

Abstract

The present invention relates to the technical field of printing nickel screens, and specifically relates to an acid and alkali resistant high-strength composite printing nickel screen and a preparation method thereof; the composite printing nickel screen includes a printing nickel screen matrix, and an electroplated nickel layer, an electroplated chromium layer and a photosensitive resin layer are sequentially arranged on the surface of the printing nickel screen matrix from inside to outside; the photosensitive resin layer is obtained by a thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin; the preparation method includes: S1, plating nickel on a mandrel in a first nickel plating electroplating solution, separating the nickel screen from the mandrel to obtain a printing nickel screen matrix; S2, plating nickel on the printing nickel screen matrix in a second nickel plating electroplating solution so that the surface of the printing nickel screen matrix is covered with an electroplated nickel layer; and then chromium plating; S3, preparing a photosensitive resin layer on the surface of the electroplated chromium layer. The present invention realizes the comprehensive improvement of the properties such as the strength and acid and alkali resistance of the printing nickel screen, solves the application problems of the traditional technology in harsh environments, and provides a new technical path for high-performance printing nickel screens.

Description

Technical Field

[0001] The present invention relates to the technical field of printing nickel screens, and particularly relates to an acid and alkali resistant high-strength composite printing nickel screen and a preparation method thereof. Background Art

[0002] As a key functional material in fields such as textile printing and dyeing, electronic circuit manufacturing, etc., the performance of the printing nickel screen directly affects product quality and production efficiency. In practical applications, the printing nickel screen often needs to work in harsh environments such as strong acids and strong alkalis for a long time, while bearing high mechanical stress and wear. Therefore, improving the acid and alkali resistance and mechanical strength of the printing nickel screen has become an urgent need in the industry. High acid and alkali resistance can extend the service life of the printing nickel screen in a corrosive environment, reduce the replacement frequency, and significantly reduce production costs; excellent mechanical strength can ensure that the printing nickel screen maintains stable performance under high-pressure and high-speed operating conditions, improving printing accuracy and efficiency. In addition, the development of acid and alkali resistant high-strength printing nickel screens will also expand their application scope, such as using in special environments in the chemical, medical and other fields, and promoting the technological upgrading of related industries. Therefore, researching and developing composite printing nickel screens with both high acid and alkali resistance and high mechanical strength has important practical significance and application value.

[0003] However, the current printing nickel screens on the market still have obvious deficiencies in terms of acid and alkali resistance and mechanical strength. The traditional single nickel layer structure is difficult to meet the requirements of both high corrosion resistance and high strength at the same time, while the simple multi-layer composite structure often leads to performance degradation due to poor interfacial bonding between layers. For example, the Chinese patent with the patent number CN212097930U discloses an ecological printing nickel screen, but its acid and alkali resistance and strength still need to be improved. The root cause of these problems lies in the limitations of material design and preparation processes. First, the traditional electroplating process is difficult to precisely control the microstructure of the nickel layer, affecting its mechanical properties and corrosion resistance; second, the interface design of the multi-layer structure is not optimized enough to give full play to the synergistic effect of each functional layer; third, the selection and preparation method of the surface protective layer are not good enough to achieve a balance between protection and functionality. Therefore, developing a new composite structure design and advanced preparation process to achieve the synergistic improvement of the acid and alkali resistance and mechanical strength of the printing nickel screen has become the focus and difficulty of current research. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] The purpose of the present invention is to provide an acid and alkali resistant high-strength composite printing nickel screen and a preparation method thereof, to solve the problems of insufficient strength and acid and alkali resistance performance of the current printing nickel screen.

[0006] (2) Technical Solutions

[0007] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0008] An acid and alkali resistant high-strength composite printing nickel screen, comprising a printing nickel screen matrix, on the surface of which an electroplated nickel layer, an electroplated chromium layer and a photosensitive resin layer are sequentially arranged from inside to outside;

[0009] The photosensitive resin layer is obtained by a thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin.

[0010] The composite printing nickel screen of the present invention exhibits a remarkable synergistic effect through a multi-layer composite structure. The printing nickel screen matrix and the electroplated nickel layer provide basic strength and corrosion resistance, the electroplated chromium layer increases surface hardness and wear resistance, while the photosensitive resin layer further improves the comprehensive performance of the material.

[0011] The photosensitive resin layer is obtained by a thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin. This reaction forms a highly cross-linked and chemically corrosion-resistant composite resin layer, endowing the resin layer with excellent mechanical strength and chemical stability, ensuring precise curing during the printing process to form a high-resolution pattern. Among them, the polyurethane-acrylate prepolymer mainly provides excellent mechanical properties and flexibility, etc., while the mercapto silicone resin mainly enhances the heat resistance and chemical stability of the material, etc.

[0012] Furthermore, the electroplated nickel layer contains a columnar crystal structure with island-like growth, and the average diameter of the columnar crystal structure is 50-150 nm; the electroplated nickel layer also contains a twin crystal structure.

[0013] First of all, the electroplated nickel layer contains a columnar crystal structure with island-like growth. This unique microstructure has multiple effects: on the one hand, the columnar crystal structure can effectively hinder the movement of dislocations, improving the yield strength and tensile strength of the material; on the other hand, the nano-scale gaps between the crystals can serve as a barrier to the diffusion of corrosive media, significantly enhancing the corrosion resistance of the material. In addition, this microstructure may also bring improvements in toughness and fatigue resistance, and increases the surface area, enhancing the bonding force and stability between the coatings. And the average diameter of the columnar crystals is in the range of 50-150 nm. This size not only ensures sufficient structural stability but also maintains a relatively high specific surface area, which is beneficial for subsequent functionalization or catalytic applications.

[0014] Secondly, the electroplated nickel layer also contains a twin crystal structure. This special crystal morphology further enhances the mechanical properties and corrosion resistance of the coating. The presence of the twin crystal structure makes the coating have higher hardness and toughness, and also improves the compactness of the coating, effectively blocking the penetration of corrosive media. In addition, the synergistic effect of the columnar crystal structure with island-like growth and the twin crystal structure not only improves the mechanical strength of the coating but also maintains good ductility, avoiding the problem of brittleness. This microstructure is also beneficial for improving the thermal stability and fatigue resistance of the coating, extending the service life of the coating.

[0015] Furthermore, the interface between the electroplated nickel layer and the electroplated chromium layer is wavy.

[0016] The wavy interface between the electroplated nickel layer and the electroplated chromium layer of the present invention has the following advantages: First, this unique wavy interface design significantly enhances the interfacial bonding strength. The wavy interface greatly increases the contact area between the two layers, providing more mechanical interlocking points, thereby enhancing the bonding force between the nickel layer and the chromium layer. This enhanced interfacial bonding not only improves the overall strength of the composite printing nickel screen but also effectively prevents the risk of interfacial delamination, greatly enhancing the service life and reliability of the product. Second, the wavy interface helps to relieve the interfacial stress. During the use of the printing nickel screen, stress may be generated between different material layers due to the difference in thermal expansion coefficients. The wavy interface can better disperse and absorb these stresses, reducing stress concentration, thereby improving the fatigue resistance and durability of the material. In addition, this interface structure can also enhance the overall flexibility of the composite printing nickel screen. The wavy interface allows for a certain degree of elastic deformation space while maintaining the structural integrity, enabling the printing nickel screen to have better adaptability when subjected to external forces. This design may also bring unexpected synergistic effects. For example, the wavy interface may affect the growth mode of the electroplated chromium layer, promoting the formation of a denser and more uniform chromium layer structure, further enhancing the surface wear resistance and corrosion resistance. At the same time, this interface structure may change the thermal and electrical conductivity characteristics of the material at the microscale, bringing new functional advantages to the printing nickel screen. Generally speaking, the wavy interface design between the electroplated nickel layer and the electroplated chromium layer is a multi-functional and efficient innovation. It not only enhances the interfacial bonding and improves the stability of the overall structure but also comprehensively improves the comprehensive performance of the composite printing nickel screen through stress dispersion, flexibility enhancement, and potential synergistic effects, providing new ideas and methods for the design and preparation of high-performance printing nickel screens.

[0017] Furthermore, the thickness of the printing nickel screen substrate is 40 - 50 μm, and the thickness of the electroplated nickel layer is 60 - 80 μm;

[0018] the thickness of the electroplated chromium layer is 20 - 45 μm; the thickness of the photosensitive resin layer is 15 - 35 μm.

[0019] First, the thicknesses of the printing nickel screen substrate and the electroplated nickel layer are respectively controlled within 40 - 50 μm and 60 - 80 μm. This thickness design aims to provide sufficient mechanical strength and corrosion resistance. The thickness of the electroplated chromium layer is controlled within 20 - 45 μm, providing excellent surface hardness and wear resistance for the entire structure.

[0020] Further, the preparation method of the photosensitive resin layer comprises the following steps: by weight, mix 20 - 45 parts of polyurethane - acrylate prepolymer, 0.5 - 2.0 parts of 1 - hydroxycyclohexyl phenyl ketone, and 15 - 30 parts of mercapto silicone resin at a rotation speed of 2000 - 3000 r / min for 30 - 60 min, then coat it on the electroplated chromium layer, and then cure it under ultraviolet light with a wavelength of 365 nm and a radiation intensity of 8.0 - 10.5 mW.cm −2 for 30 - 45 s to obtain the photosensitive resin layer after complete curing.

[0021] The preparation method of the photosensitive resin layer ensures the uniformity of the resin layer and the consistency of performance by precisely controlling the mixing ratio, rotation speed, mixing time, and curing conditions of the polyurethane - acrylate prepolymer and the mercapto silicone resin.

[0022] Further, the preparation method of the polyurethane - acrylate prepolymer comprises the following steps: by weight, add 15 - 25 parts of polytetramethylene ether glycol, 0.20 - 0.30 parts of trimethylolpropane, and 0.015 - 0.025 parts of dibutyltin dilaurate into a three - necked flask, stir and mix, and heat to 55 - 65 °C, then dropwise add 5.0 - 9.0 parts of isophorone diisocyanate, then continuously stir the obtained mixture at 55 - 65 °C for 60 - 120 min, then add 4.0 - 8.0 parts of hydroxypropyl acrylate, continue to stir for 30 - 45 min, and finally treat it at 110 - 120 °C and a pressure of 120 - 130 mmHg for 60 - 120 min to remove the raw material residues in the obtained mixture and generate a transparent viscous polyurethane - acrylate prepolymer;

[0023] The preparation method of the mercapto silicone resin comprises the following steps: by weight, add 150 - 170 parts of dimethyldiethoxysilane, 75 - 85 parts of methyltrimethoxysilane, 180 - 200 parts of 3 - (trimethoxysilyl) - 1 - propanethiol, and 210 - 230 parts of toluene into a three - necked flask, stir and mix, and heat to 45 - 55 °C, then dropwise add 150 - 170 parts of hydrochloric acid with a mass fraction of 5 - 10%, then stir the obtained mixture at 55 - 65 °C for 240 - 360 min, then let it stand for layering, separate the aqueous phase and the organic phase, retain the organic phase, then wash the organic phase to neutral, and finally perform vacuum concentration treatment at 110 - 120 °C and a pressure of 120 - 130 mmHg for 120 - 240 min to remove the solvent and volatile by - products in the organic phase and obtain a transparent mercapto silicone resin.

[0024] The preparation of the polyurethane-acrylate prepolymer of the present invention involves the precise proportioning of various raw materials and the control of reaction conditions, aiming to obtain an ideal molecular structure and properties, providing a good matrix for the cross-linking reaction of the resin layer. The preparation of the mercapto silicone resin also involves the precise proportioning of various silane compounds and the control of reaction conditions, aiming to obtain a product with a specific structure and reaction activity.

[0025] In summary, through the setting of the multi-layer composite structure and the combination of its microscopic crystal structure characteristics, the acid and alkali resistant and high-strength composite printing nickel screen of the present invention realizes the comprehensive improvement of the composite printing nickel screen in multiple performance indicators such as strength, corrosion resistance, and wear resistance. This innovative technical solution not only solves the problems of easy corrosion and insufficient strength of traditional printing nickel screens in harsh environments, but also provides a new technical path for the preparation of high-performance printing nickel screens. Through the synergistic effect between the functional layers, the present invention has successfully developed an acid and alkali resistant and high-strength composite printing nickel screen with excellent comprehensive performance.

[0026] The present invention also provides a method for preparing an acid and alkali resistant and high-strength composite printing nickel screen, comprising the following steps:

[0027] S1. Place the core mold in the first nickel plating electroplating solution for nickel plating, and separate the nickel screen formed by nickel plating from the core mold to obtain the printing nickel screen substrate;

[0028] S2. Then place the printing nickel screen substrate in the second nickel plating electroplating solution for nickel plating, so that the surface of the printing nickel screen substrate is covered with an electroplated nickel layer; then place it in a chromium plating electroplating solution for chromium plating, so that the surface of the electroplated nickel layer is covered with an electroplated chromium layer;

[0029] S3. Prepare a photosensitive resin layer on the surface of the electroplated chromium layer.

[0030] Further, in the step S1, the composition of the first nickel plating electroplating solution includes: nickel sulfate 140-150 g / L, nickel chloride 38-42 g / L, boric acid 32-36 g / L, 1,4-butyne diol 0.26-0.30 g / L, sodium dodecyl sulfate 0.08-0.12 g / L, sodium thiazolinyl dithiopropane sulfonate 60-100 mg / L, and the balance is water.

[0031] Further, in the step S1, the process parameters for nickel plating are: the temperature is 40-45 °C, the current density is 2.5-3.5 A / dm 2 , and the electroplating time is 35-45 min.

[0032] Further, in the step S2, the composition of the second nickel plating bath includes: nickel sulfate 140-150 g / L, nickel chloride 38-42 g / L, boric acid 32-36 g / L, rare earth additive 0.5-3.5 g / L, 1,4-butyne diol 0.26-0.30 g / L, sodium dodecyl sulfate 0.08-0.12 g / L, sodium thiazolinyl dithiopropane sulfonate 60-100 mg / L, and the balance is water; the rare earth additive is a composition of one or two of lanthanum oxide and lanthanum chloride;

[0033] The process parameters for nickel plating are: temperature 35-45 °C, current density 8-12 A / dm 2 , and the electroplating time is 120-240 min.

[0034] Further, in the step S3, the composition of the chromium plating bath includes: chromium sulfate 0.4-0.8 mol / L, formic acid 0.7-1.2 mol / L, ammonium chloride 0.8-1.2 mol / L, potassium chloride 0.8-1.2 mol / L, polyethylene glycol 0.02-0.07 mol / L, and the balance is water;

[0035] The process parameters for chromium plating are: temperature 55-65 °C, current density 65-75 A / dm 2 , and the electroplating time is 40-70 min.

[0036] The preparation method of the present invention includes four main steps: preparing a printed nickel screen substrate, preparing a nickel plating layer, preparing a chromium plating layer, and preparing a photosensitive resin layer. Each step is carefully designed to achieve specific functions and produce a synergistic effect with other steps.

[0037] The preparation of the printed nickel screen substrate uses a carefully formulated electroplating bath, which contains main components such as nickel sulfate, nickel chloride, and boric acid, as well as additives such as 1,4-butyne diol, sodium dodecyl sulfate, and sodium thiazolinyl dithiopropane sulfonate; the purpose of these additives is to regulate the structure and properties of the plating layer. Among them, 1,4-butyne diol may be used to improve the brightness and flatness of the plating layer, sodium dodecyl sulfate as a surfactant can improve the wettability of the electroplating bath, and sodium thiazolinyl dithiopropane sulfonate may be used to improve the ductility and toughness of the plating layer. The precise control of electroplating process parameters, including temperature, current density, and electroplating time, aims to obtain an ideal plating layer thickness and structure.

[0038] The preparation of the electroplated nickel layer is a key innovation of the present invention. Based on the first nickel plating bath, rare earth additives (lanthanum oxide or lanthanum chloride or a mixture of both) are added. The purpose of this design is to change the microstructure of the nickel layer by adding rare earth elements. Rare earth elements may affect the crystallization process of nickel and promote the formation of columnar crystal structures with island-like growth. This special microstructure can not only improve the strength of the material but also enhance its corrosion resistance. The process parameters of the electroplated nickel layer, especially the lower current density and longer electroplating time, further facilitate the formation of the ideal columnar crystal structure.

[0039] The preparation of the electroplated chromium layer uses a unique electroplating bath composition, including chromium sulfate, formic acid, ammonium chloride, potassium chloride, and polyethylene glycol. The purpose of this formulation is to obtain a high-quality chromium coating. Formic acid may act as a reducing agent, ammonium chloride and potassium chloride may be used to improve conductivity and coating quality, while polyethylene glycol may be used to adjust the stress of the coating and improve its brightness. The selection of electroplating process parameters, especially the higher current density, aims to obtain a dense and hard chromium coating, thereby providing excellent surface hardness and wear resistance.

[0040] This multi-step preparation method of the present invention exhibits significant synergistic effects. The printed nickel screen substrate provides the basic strength and corrosion resistance for the entire structure. The electroplated nickel layer further enhances these properties through its special microstructure, and the electroplated chromium layer provides excellent surface properties. The interface design between the layers, especially the wavy interface that may form between the electroplated nickel layer and the electroplated chromium layer, enhances the interfacial bonding strength and improves the stability of the overall structure.

[0041] Furthermore, for the preparation of the photosensitive resin layer, it not only improves the comprehensive properties of the material but also brings new functional possibilities to the printed nickel screen.

[0042] Generally speaking, through a carefully designed multi-step preparation method, the present invention achieves a comprehensive improvement in multiple performance indicators of the printed nickel screen, such as strength, corrosion resistance, and wear resistance. Each step is precisely controlled, including the electroplating bath composition, additive selection, process parameter setting, etc., all of which aim to obtain the ideal microstructure and macroscopic properties. Through the synergistic effect between the functional layers, the present invention successfully develops a high-strength composite printed nickel screen with excellent comprehensive properties that is resistant to acids and alkalis. This innovative preparation method not only solves the problems of traditional printed nickel screens being easily corroded and having insufficient strength in harsh environments but also provides a new technical path for the preparation of high-performance printed nickel screens, making an important contribution to the technological progress of related fields.

[0043] (3) Beneficial technical effects

[0044] 1. In the composite printing nickel screen of the present invention, the nickel screen substrate and the electroplated nickel layer provide basic strength and corrosion resistance, the electroplated chromium layer increases surface hardness and wear resistance, while the photosensitive resin layer further enhances the comprehensive performance of the material. Among them, the present invention combines a polyurethane-acrylate prepolymer with a mercapto silicone resin through a thiol-ene click chemical reaction to form a highly crosslinked and chemically corrosion-resistant composite photosensitive resin layer, significantly improving the performance and application range of the printing nickel screen. This resin layer has excellent mechanical strength and chemical stability, can be precisely cured during the printing process to form high-resolution patterns. The precisely controlled preparation process ensures the uniformity and performance consistency of the resin layer.

[0045] 2. Through the innovative design of the electroplating process, the present invention significantly improves the comprehensive performance of the nickel layer, opening up a new way for the development of high-performance coating materials. Compared with traditional technologies, the electroplated nickel layer achieved by the present invention has a unique island-like growth columnar crystal structure and twin crystal structure, and this microscopic structure design brings various performance advantages. First of all, the island-like columnar crystal structure increases the surface area, improves the reaction activity, effectively reduces the internal stress, and enhances the bonding force and stability of the coating. Secondly, the precisely controlled columnar crystal diameter (50 - 150 nm) not only ensures the structural stability but also maintains a high specific surface area, increasing the contact area. Moreover, the introduction of the twin crystal structure further enhances the mechanical properties and corrosion resistance of the coating, improving hardness, toughness, and density. The synergistic effect of these structural features not only improves the mechanical strength of the coating but also maintains good ductility, avoids brittleness problems, and at the same time enhances the thermal stability and fatigue resistance.

[0046] 3. By designing a wavy interface between the electroplated nickel layer and the electroplated chromium layer, the present invention significantly improves the comprehensive performance of the composite printing nickel screen. This innovative structure increases the interlayer contact area, provides more mechanical interlocking points, greatly enhances the interlayer bonding force, effectively prevents interlayer peeling, and extends the service life of the product. The wavy interface can also better disperse and absorb the interlayer stress, reduce stress concentration, improve the fatigue resistance and durability of the material. This design enhances the overall flexibility of the printing nickel screen, provides a certain elastic deformation space, and enables it to have better adaptability when subjected to external forces. The wavy interface may promote the formation of a denser and more uniform chromium layer structure, further enhancing the surface wear resistance and corrosion resistance, and may change the thermal and electrical conductivity characteristics of the material at the microscale, bringing new functional advantages.

[0047] 4. The acid- and alkali-resistant high-strength composite printing nickel screen proposed by the present invention realizes a comprehensive improvement in performance through a carefully designed multi-layer structure. The electroplated nickel layer provides basic strength and corrosion resistance. Its unique island-like columnar crystal structure and twin crystal structure effectively hinder the movement of dislocations, improve the yield strength and tensile strength. At the same time, the nano-scale gaps serve as a corrosion barrier to enhance the corrosion resistance. The wavy interface between the electroplated nickel layer and the chromium layer increases the contact area, disperses stress, and reduces the risk of peeling. The electroplated chromium layer provides excellent surface hardness and wear resistance. The innovative photosensitive resin layer achieves high cross-linking through the click chemical reaction of polyurethane-acrylate prepolymer and mercapto silicone resin, providing mechanical properties, flexibility, heat resistance and chemical stability. The synergistic effect of each layer significantly improves the comprehensive performance of the printing nickel screen, solving the problems of easy corrosion and insufficient strength in traditional technologies under harsh environments. The precisely controlled preparation process ensures the best ratio and performance of each component. This innovation provides high-performance solutions for high-end printing, electronics, medical and other fields, and is expected to promote the technological upgrading of related industries and the development of new applications. Description of the Drawings

[0048] Figure 1 TEM image of the columnar crystal structure of the island growth of the electroplated nickel layer prepared in Example 1 of the present invention.

[0049] Figure 2 TEM image of the twin crystal structure of the electroplated nickel layer prepared in Example 1 of the present invention.

[0050] Figure 3 XRD pattern of the phases of the printing nickel screen substrate and the electroplated nickel layer prepared in Example 1 of the present invention.

[0051] Figure 4 TEM image of the interface between the electroplated nickel layer and the electroplated chromium layer prepared in Example 1 of the present invention.

[0052] Figure 5 FTIR image of the photosensitive resin layer prepared in Example 1 of the present invention.

[0053] Figure 6 TEM image of the electroplated nickel layer prepared in Comparative Example 1 of the present invention.

[0054] Figure 7 TEM image of the interface between the electroplated nickel layer and the electroplated chromium layer prepared in Comparative Example 2 of the present invention. Detailed Description of the Invention

[0055] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0056] In the case where specific conditions are not specified, the operations in the examples are carried out under conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments used, if the manufacturer is not indicated, they are all common products on the market. For parts not mentioned in the technical content of the present invention, they will be processed with reference to the prior art. Unless otherwise specified, the following examples and comparative examples will be carried out in parallel tests and use the same processing steps and parameters. Table 1 shows the reagents required for the examples and comparative examples and the corresponding purchasing companies.

[0057] Table 1 Reagents Required for Examples and Comparative Examples and the Corresponding Purchasing Companies

[0058]

[0059] Example 1:

[0060] An acid and alkali resistant high-strength composite printing nickel screen, comprising a printing nickel screen matrix, on the surface of which an electroplated nickel layer, an electroplated chromium layer and a photosensitive resin layer are sequentially arranged from the inside to the outside; the electroplated nickel layer contains a columnar crystal structure with island growth, the average diameter of the columnar crystal structure is 50 nm, and the electroplated nickel layer also contains a twin crystal structure; the interface between the electroplated nickel layer and the electroplated chromium layer is wavy; the thicknesses of the printing nickel screen matrix and the electroplated nickel layer are 40 μm and 60 μm respectively; the thickness of the electroplated chromium layer is 20 μm; the thickness of the photosensitive resin layer is 15 μm.

[0061] In this example, the photosensitive resin layer is obtained by a thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin. The specific preparation method of the photosensitive resin layer includes the following steps:

[0062] (1) By weight, add 15 parts of polytetramethylene ether glycol, 0.20 parts of trimethylolpropane, and 0.015 parts of dibutyltin dilaurate to a 100 mL three-necked flask, stir and mix, and heat to 55 °C, then dropwise add 5.0 parts of isophorone diisocyanate, and then continuously stir the obtained mixture at 55 °C for 60 min, then add 4.0 parts of hydroxypropyl acrylate, continue to stir for 30 min, and finally treat at 110 °C and 120 mmHg pressure for 60 min to remove the raw material residues in the mixture, generating a transparent viscous polyurethane-acrylate prepolymer.

[0063] (2) Add 150 parts of dimethyldiethoxysilane, 75 parts of methyltrimethoxysilane, 180 parts of 3-(trimethoxysilyl)-1-propanethiol, and 210 parts of toluene into a 1000 mL three-necked flask, stir and mix them, and heat to 45 °C. Then, dropwise add 150 parts of 5% hydrochloric acid by mass fraction. Subsequently, stir the mixture at 55 °C for 240 min, then let it stand for liquid separation, separate the aqueous phase and the organic phase, retain the organic phase. Then wash the organic phase with water until it is neutral. Finally, perform vacuum concentration treatment at 110 °C and 120 mmHg pressure for 120 min to remove the solvent and volatile by-products in the organic phase, and obtain a transparent mercapto silicone resin.

[0064] (3) Mix 20 parts of polyurethane-acrylate prepolymer, 0.5 part of 1-hydroxycyclohexyl phenyl ketone, and 15 parts of mercapto silicone resin at a rotation speed of 2000 r / min for 30 min, then coat it on the electroplated chromium layer. Then, cure it under ultraviolet light with a wavelength of 365 nm and a radiation intensity of 8.0 mW·cm −2 for 30 s, and a photosensitive resin layer is obtained after complete curing.

[0065] This embodiment also provides a preparation method of an acid and alkali resistant and high-strength composite printing nickel screen, including the following steps:

[0066] S1. Prepare a printing nickel screen substrate: Place the core mold into the first nickel plating electroplating solution for nickel plating, separate the nickel screen formed by nickel plating from the core mold, and obtain the printing nickel screen substrate.

[0067] The composition of the first nickel plating electroplating solution includes: nickel sulfate 140 g / L, nickel chloride 38 g / L, boric acid 32 g / L, 1,4-butyne diol 0.26 g / L, sodium dodecyl sulfate 0.08 g / L, sodium thiazolinyl dithiopropane sulfonate 60 mg / L, and the balance is water. The process parameters of nickel plating are: temperature is 40 °C, current density is 2.5 A / dm 2 , and the electroplating time is 35 min.

[0068] S2. Then place the printing nickel screen substrate into the second nickel plating electroplating solution for nickel plating to cover the surface of the printing nickel screen substrate with an electroplated nickel layer; then place it in the chromium plating electroplating solution for chromium plating to cover the surface of the electroplated nickel layer with an electroplated chromium layer;

[0069] The composition of the second nickel plating electroplating solution includes: nickel sulfate 140 g / L, nickel chloride 38 g / L, boric acid 32 g / L, lanthanum oxide 0.5 g / L, 1,4-butyne diol 0.26 g / L, sodium dodecyl sulfate 0.08 g / L, sodium thiazolinyl dithiopropane sulfonate 60 mg / L, and the balance is water. The process parameters of nickel plating are: temperature is 35 °C, current density is 8 A / dm 2 , and the electroplating time is 120 min;

[0070] The composition of the electroplating solution for the electroplated chromium layer includes: chromium sulfate at 0.4 mol / L, formic acid at 0.7 mol / L, ammonium chloride at 0.8 mol / L, potassium chloride at 0.8 mol / L, polyethylene glycol at 0.02 mol / L, and the balance is water. The process parameters for chromium plating are: temperature at 55 °C, current density 65 A / dm 2 , and electroplating time 40 min.

[0071] S3. Prepare the photosensitive resin layer: Prepare the photosensitive resin layer on the surface of the electroplated chromium layer (prepare the photosensitive resin layer according to the method in step (3) of this embodiment).

[0072] The present invention is strongly proven by a series of experimental results and analysis data for its unique structural design and excellent performance.

[0073] Figure 1 The TEM image of clearly shows the island-like columnar crystal structure of the electroplated nickel layer, and this structure is beneficial to improving the mechanical strength and corrosion resistance of the coating.

[0074] Figure 2 The TEM image of reveals the twin crystal structure in the electroplated nickel layer, and this structure can significantly enhance the comprehensive performance of the coating.

[0075] Figure 3 The XRD pattern of compares the phase compositions of the printed nickel mesh substrate and the electroplated nickel layer, providing direct evidence for the differences in the two-layer structure.

[0076] Figure 4 shows the wavy interface between the electroplated nickel layer and the electroplated chromium layer, and this special interface structure helps to enhance the interfacial bonding force and improve the overall performance.

[0077] Figure 5 The FTIR spectrum of details the chemical composition and reaction degree of the photosensitive resin layer. The characteristic absorption peaks at 2860 - 2900 cm -1 , 1730 cm -1 and 1531 cm -1 correspond to the polyether chain segment, carbonyl group and NH group of polyurethane respectively, confirming the expected chemical structure. At the same time, the absence of the characteristic absorption peak of the isocyanate group in the range of 2260 - 2280 cm -1 and the disappearance of the C-C and CH characteristic absorptions at 1635 cm -1 and 813 cm -1 strongly prove the complete curing of the photosensitive resin. These results comprehensively illustrate that the present invention has successfully designed and prepared a composite coating with special structure and excellent performance, providing sufficient scientific basis for its superiority in practical applications.

[0078] Example 2:

[0079] An acid and alkali resistant high-strength composite printing nickel screen, comprising a printing nickel screen matrix, wherein an electroplated nickel layer, an electroplated chromium layer and a photosensitive resin layer are sequentially arranged on the surface of the printing nickel screen matrix from inside to outside; the electroplated nickel layer contains a columnar crystal structure with island growth, the average diameter of the columnar crystal structure is 80 nm, and the electroplated nickel layer also contains a twin crystal structure; the interface between the electroplated nickel layer and the electroplated chromium layer is wavy; the thicknesses of the printing nickel screen matrix and the electroplated nickel layer are 43 μm and 66 μm respectively; the thickness of the electroplated chromium layer is 28 μm; the thickness of the photosensitive resin layer is 21 μm.

[0080] In this embodiment, the photosensitive resin layer is obtained by a thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin; the specific preparation method of the photosensitive resin layer comprises the following steps:

[0081] (1) By weight, add 18 parts of polytetramethylene ether glycol, 0.23 parts of trimethylolpropane, and 0.018 parts of dibutyltin dilaurate into a 100 mL three-necked flask, stir and mix, and heat to 58 °C, then dropwise add 6.2 parts of isophorone diisocyanate, and then keep the obtained mixture stirring at 58 °C for 78 min, then add 5.2 parts of hydroxypropyl acrylate, continue stirring for 35 min, and finally treat at 113 °C and 123 mmHg for 80 min to remove the raw material residues in the mixture, generating a transparent viscous polyurethane-acrylate prepolymer.

[0082] (2) Add 156 parts of dimethyldiethoxysilane, 78 parts of methyltrimethoxysilane, 186 parts of 3-(trimethoxysilyl)-1-propanethiol and 216 parts of toluene into a 1000 mL three-necked flask, stir and mix, and heat to 48 °C, then dropwise add 156 parts of 6% hydrochloric acid by mass, and then keep the obtained mixture stirring at 58 °C for 276 min, then let it stand for layering, separate the aqueous phase and the organic phase, retain the organic phase, then wash the organic phase to neutral, and finally carry out vacuum concentration treatment at 113 °C and 123 mmHg for 160 min to remove the solvent and volatile by-products in the organic phase, obtaining a transparent mercapto silicone resin.

[0083] (3) Mix 28 parts of polyurethane-acrylate prepolymer, 1.0 part of 1-hydroxycyclohexyl phenyl ketone and 20 parts of mercapto silicone resin at a rotation speed of 2300 r / min for 39 min, then coat it on the electroplated chromium layer, and then cure it under ultraviolet light with a wavelength of 365 nm and a radiation intensity of 8.8 mW.cm −2 for 35 s, and obtain the photosensitive resin layer after complete curing.

[0084] This embodiment also provides a preparation method of an acid and alkali resistant high-strength composite printing nickel screen, comprising the following steps:

[0085] S1. Preparation of the printed nickel screen substrate: Place the core mold in the first nickel plating bath for nickel plating, separate the nickel screen formed by nickel plating from the core mold to obtain the printed nickel screen substrate;

[0086] The composition of the first nickel plating bath includes: nickel sulfate 143 g / L, nickel chloride 39 g / L, boric acid 33 g / L, 1,4-butyne diol 0.27 g / L, sodium dodecyl sulfate 0.09 g / L, sodium thiazolinyl dithiopropane sulfonate 72 mg / L, and the balance is water. The process parameters for nickel plating are: temperature 42 °C, current density 2.8 A / dm 2 , and the electroplating time is 38 min.

[0087] S2. Place the printed nickel screen substrate in the second nickel plating bath for nickel plating so that the surface of the printed nickel screen substrate is covered with an electroplated nickel layer; then place it in a chromium plating bath for chromium plating so that the surface of the electroplated nickel layer is covered with an electroplated chromium layer.

[0088] The composition of the second nickel plating bath includes: nickel sulfate 143 g / L, nickel chloride 39 g / L, boric acid 33 g / L, lanthanum chloride 1.4 g / L, 1,4-butyne diol 0.27 g / L, sodium dodecyl sulfate 0.09 g / L, sodium thiazolinyl dithiopropane sulfonate 72 mg / L, and the balance is water. The process parameters for nickel plating are: temperature 38 °C, current density 9 A / dm 2 , and the electroplating time is 156 min;

[0089] The composition of the electroplating bath for the electroplated chromium layer includes: chromium sulfate 0.5 mol / L, formic acid 0.9 mol / L, ammonium chloride 0.9 mol / L, potassium chloride 0.9 mol / L, polyethylene glycol 0.04 mol / L, and the balance is water. The process parameters for chromium plating are: temperature 58 °C, current density 68 A / dm 2 , and the electroplating time is 49 min.

[0090] S3. Preparation of the photosensitive resin layer: Prepare a photosensitive resin layer on the surface of the electroplated chromium layer (prepare the photosensitive resin layer according to the method in step (3) of this example).

[0091] Example 3:

[0092] An acid and alkali resistant high-strength composite printed nickel screen, including a printed nickel screen substrate, on the surface of which an electroplated nickel layer, an electroplated chromium layer and a photosensitive resin layer are sequentially arranged from inside to outside; the electroplated nickel layer has a columnar crystal structure with island-like growth, and the average diameter of the columnar crystal structure is 110 nm; the interface between the electroplated nickel layer and the electroplated chromium layer is wavy; the thicknesses of the printed nickel screen substrate and the electroplated nickel layer are 46 μm and 72 μm respectively; the thickness of the electroplated chromium layer is 35 μm; the thickness of the photosensitive resin layer is 27 μm.

[0093] In this embodiment, the photosensitive resin layer is obtained by the thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin; the preparation method of the photosensitive resin layer specifically includes the following steps:

[0094] (1) By weight, add 21 parts of polytetramethylene ether glycol, 0.26 parts of trimethylolpropane, and 0.021 parts of dibutyltin dilaurate to a 100 mL three-necked flask, stir and mix, and heat to 61 °C. Then, dropwise add 7.4 parts of isophorone diisocyanate. Subsequently, continuously stir the obtained mixture at 61 °C for 96 min, then add 6.4 parts of hydroxypropyl acrylate, continue stirring for 40 min, and finally treat at 116 °C and 126 mmHg pressure for 100 min to remove the raw material residues in the mixture, generating a transparent viscous polyurethane-acrylate prepolymer.

[0095] (2) Add 162 parts of dimethyldiethoxysilane, 81 parts of methyltrimethoxysilane, 192 parts of 3-(trimethoxysilyl)-1-propanethiol, and 222 parts of toluene to a 1000 mL three-necked flask, stir the mixture and heat to 51 °C. Then, dropwise add 162 parts of hydrochloric acid with a mass fraction of 9%. Subsequently, stir the obtained mixture at 61 °C for 312 min, then let it stand for stratification, separate the aqueous phase and the organic phase, retain the organic phase, then wash the organic phase to neutral, and finally perform vacuum concentration treatment at 116 °C and 126 mmHg pressure for 200 min to remove the solvent and volatile by-products in the organic phase, obtaining a transparent mercapto silicone resin.

[0096] (3) Mix 35 parts of the polyurethane-acrylate prepolymer, 1.5 parts of 1-hydroxycyclohexyl phenyl ketone, and 24 parts of the mercapto silicone resin at a rotation speed of 2600 r / min for 48 min, then coat it on the electroplated chromium layer, and then cure it under ultraviolet light with a wavelength of 365 nm and a radiation intensity of 9.5 mW·cm −2 for 39 s. After complete curing, a photosensitive resin layer is obtained.

[0097] This embodiment also provides a preparation method of an acid and alkali resistant and high strength composite printing nickel screen, including the following steps:

[0098] S1. Prepare a printing nickel screen substrate: Place the core mold in the first nickel plating electroplating solution for nickel plating, separate the nickel screen formed by nickel plating from the core mold to obtain a printing nickel screen substrate;

[0099] The composition of the first nickel plating electroplating solution includes: nickel sulfate 146 g / L, nickel chloride 40 g / L, boric acid 34 g / L, 1,4-butyne diol 0.28 g / L, sodium dodecyl sulfate 0.10 g / L, sodium thiazolinyl dithiopropane sulfonate 84 mg / L, and the balance is water. The process parameters of nickel plating are: temperature is 43 °C, current density 3.1 A / dm2 , the electroplating time is 41 min.

[0100] S2. Then, put the printed nickel screen substrate into the second nickel electroplating solution for nickel electroplating, so that the surface of the printed nickel screen substrate is covered with a nickel electroplating layer; then place it in the chromium electroplating solution for chromium electroplating, so that the surface of the nickel electroplating layer is covered with a chromium electroplating layer;

[0101] The composition of the second nickel electroplating solution includes: nickel sulfate 146 g / L, nickel chloride 40 g / L, boric acid 34 g / L, rare earth additive 2.3 g / L, 1,4-butyne diol 0.28 g / L, sodium dodecyl sulfate 0.10 g / L, sodium thiazolinyl dithiopropane sulfonate 84 mg / L, and the balance is water; the rare earth additive is composed of lanthanum oxide and lanthanum chloride mixed in a mass ratio of 3:7. The process parameters for nickel electroplating are: temperature is 41 °C, current density is 10 A / dm 2 , the electroplating time is 192 min.

[0102] The composition of the electroplating solution for the chromium electroplating layer includes: chromium sulfate 0.6 mol / L, formic acid 1.0 mol / L, ammonium chloride 1.0 mol / L, potassium chloride 1.0 mol / L, polyethylene glycol 0.05 mol / L, and the balance is water. The process parameters for chromium electroplating are: temperature is 61 °C, current density is 71 A / dm 2 , the electroplating time is 58 min.

[0103] S3. Prepare the photosensitive resin layer: Prepare the photosensitive resin layer on the surface of the chromium electroplating layer (prepare the photosensitive resin layer according to the method in step (3) of this embodiment).

[0104] Example 4:

[0105] An acid and alkali resistant high-strength composite printed nickel screen, including a printed nickel screen substrate, and a nickel electroplating layer, a chromium electroplating layer, and a photosensitive resin layer are sequentially arranged on the surface of the printed nickel screen substrate from inside to outside; the nickel electroplating layer contains a columnar crystal structure with island-like growth, the average diameter of the columnar crystal structure is 150 nm, and the nickel electroplating layer also contains a twin crystal structure; the interface between the nickel electroplating layer and the chromium electroplating layer is wavy; the thicknesses of the printed nickel screen substrate and the nickel electroplating layer are 50 μm and 80 μm respectively; the thickness of the chromium electroplating layer is 45 μm; the thickness of the photosensitive resin layer is 35 μm.

[0106] The photosensitive resin layer in this embodiment is obtained by the thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin; the preparation method of the photosensitive resin layer specifically includes the following steps:

[0107] (1) Weighing in parts by weight, add 25 parts of polytetramethylene ether glycol, 0.30 part of trimethylolpropane, and 0.025 part of dibutyltin dilaurate into a 100 mL three-necked flask. Stir and mix, then heat to 65 °C. Next, dropwise add 9.0 parts of isophorone diisocyanate. Subsequently, continuously stir the obtained mixture at 65 °C for 120 min. Then add 8.0 parts of hydroxypropyl acrylate and continue stirring for 45 min. Finally, treat at 120 °C and 130 mmHg pressure for 120 min to remove the raw material residues in the mixture, generating a transparent and viscous polyurethane-acrylate prepolymer.

[0108] (2) Add 170 parts of dimethyldiethoxysilane, 85 parts of methyltrimethoxysilane, 200 parts of 3-(trimethoxysilyl)-1-propanethiol, and 230 parts of toluene into a 1000 mL three-necked flask. Stir the mixture and heat to 55 °C. Then dropwise add 170 parts of 10% hydrochloric acid by mass. Subsequently, stir the obtained mixture at 65 °C for 360 min. Then let it stand for liquid separation, separate the aqueous phase and the organic phase, retain the organic phase. Next, wash the organic phase until it is neutral. Finally, perform vacuum concentration treatment at 120 °C and 130 mmHg pressure for 240 min to remove the solvents and volatile by-products in the organic phase, obtaining a transparent mercapto silicone resin.

[0109] (3) Mix 45 parts of polyurethane-acrylate prepolymer, 2.0 parts of 1-hydroxycyclohexyl phenyl ketone, and 30 parts of mercapto silicone resin at a rotation speed of 3000 r / min for 60 min. Then coat it on the electroplated chromium layer. Next, cure it under ultraviolet light with a wavelength of 365 nm and a radiation intensity of 10.5 mW·cm −2 for 45 s. After complete curing, a photosensitive resin layer is obtained.

[0110] This example also provides a preparation method of an acid and alkali resistant and high strength composite printing nickel screen, including the following steps:

[0111] S1. Prepare the printing nickel screen substrate: Place the core mold into the first nickel plating electroplating solution for nickel plating. Separate the nickel screen formed by nickel plating from the core mold to obtain the printing nickel screen substrate;

[0112] The composition of the first nickel plating electroplating solution includes: nickel sulfate 150 g / L, nickel chloride 42 g / , boric acid 36 g / L, 1,4-butyne diol 0.30 g / L, sodium dodecyl sulfate 0.12 g / L, sodium 3-(thiazolin-2-yl)dithiopropane sulfonate 100 mg / L, and the balance is water. The process parameters for nickel plating are: temperature 45 °C, current density 3.5 A / dm 2 , electroplating time 45 min.

[0113] S2. Then, place the nickel screen printing substrate into the second nickel plating bath for nickel plating, so that the surface of the nickel screen printing substrate is covered with a nickel plating layer; then place it in a chromium plating bath for chromium plating, so that the surface of the nickel plating layer is covered with a chromium plating layer;

[0114] The composition of the second nickel plating bath includes: nickel sulfate 150 g / L, nickel chloride 42 g / L, boric acid 36 g / L, rare earth additive 3.5 g / L, 1,4 - butynediol 0.30 g / L, sodium dodecyl sulfate 0.12 g / L, sodium thiazolinyl dithiopropane sulfonate 100 mg / L, and the balance is water; the rare earth additive is composed of lanthanum oxide and lanthanum chloride mixed in a mass ratio of 5:5; the process parameters for nickel plating are: temperature 45 °C, current density 12 A / dm 2 , and the electroplating time is 240 min.

[0115] The composition of the electroplating bath for the chromium plating layer includes: chromium sulfate 0.8 mol / L, formic acid 1.2 mol / L, ammonium chloride 1.2 mol / L, potassium chloride 1.2 mol / L, polyethylene glycol 0.07 mol / L, and the balance is water. The process parameters for chromium plating are: temperature 65 °C, current density 75 A / dm 2 , and the electroplating time is 70 min.

[0116] S4. Prepare the photosensitive resin layer: Prepare the photosensitive resin layer on the surface of the chromium plating layer (prepare the photosensitive resin layer according to the method in step (3) of this embodiment).

[0117] Comparative Example 1:

[0118] It is basically the same as Example 1, except that when preparing the nickel plating layer, the rare earth additive is not added to the second nickel plating bath. Therefore, it can be seen from Figure 6 the transmission electron microscopy characterization that the nickel plating layer does not obtain a twin crystal structure.

[0119] Comparative Example 2:

[0120] It is basically the same as Example 1, except that when preparing the nickel plating layer, the current density is 1 A / dm 2 , and the electroplating time is 480 min. Therefore, the nickel plating layer does not obtain an island - like columnar crystal structure. Therefore, it can be seen from Figure 7 the transmission electron microscopy characterization that the interface between the nickel plating layer and the chromium plating layer is linear.

[0121] Comparative Example 3:

[0122] It is basically the same as Example 1, except that when preparing the photosensitive resin layer, the dosage of 3 - (trimethoxysilyl) - 1 - propanethiol added is 130 parts.

[0123] Performance test:

[0124] The solvent resistance test of the printed nickel screen includes four aspects: water resistance, acid resistance, oil resistance, and alkali resistance, all of which are evaluated by the immersion method. The water resistance test follows the GB / T 1733-1993 standard and is immersed in distilled water or deionized water at 23±2°C for 30 days; the acid resistance and alkali resistance tests are carried out according to Method A in GB / T 9274-1988 and are immersed in 10% sulfuric acid and sodium hydroxide solutions for 30 days respectively; the oil resistance test also refers to Method A in GB / T 9274-1988, but is immersed in 120# gasoline for 168 hours.

[0125] After all the tests are completed, the samples are dried with filter paper and visually observed under scattered daylight. The evaluation criteria are as follows: no abnormalities in the water resistance test are considered qualified; color change and loss of gloss are allowed in the acid resistance and oil resistance tests; slight color change and slight loss of gloss are allowed in the alkali resistance test. In addition, if there are no obvious paint film abnormalities such as blistering, cracking, peeling, and rusting, it can be rated as "no abnormality", that is, considered to pass the test. This comprehensive test method comprehensively evaluates the performance of the printed nickel screen in various solvent environments.

[0126] Tensile strength: The tensile strength test of the printed nickel screen usually refers to the standard of GB / T 228-2010 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature".

[0127] Peel strength: The peel strength test uses a soft substrate peel fixture, follows the IPC-TM-650 standard, and measures the adhesion strength between the resin layer and the printed nickel screen substrate by peeling the polyimide film at a 90° angle. The result is expressed in N / mm.

[0128] Nickel residue: The nickel residue test refers to GB / T 18885-2020 "Technical requirements for ecological textiles". The test sample is the coated woven printed fabric after continuously printing 30,000 meters. This comprehensive test method not only evaluates the mechanical properties of the photosensitive resin layer but also pays attention to the possible environmental impacts during its long-term use, reflecting the comprehensive consideration of product quality and environmental safety.

[0129] The performance of the printed nickel screens in Examples 1-4 and Comparative Examples 1-3 is summarized in Table 2.

[0130] Table 2 Summary of the performance of the printed nickel screens in Examples 1-4 and Comparative Examples 1-3

[0131]

[0132] The main difference between Comparative Example 1 and Example 1 is that rare earth additives were not added during the preparation of the electroplated nickel layer, so the electroplated nickel layer did not obtain a twin crystal structure. As can be seen from Table 2, the tensile strength and peel strength of Comparative Example 1 are also lower, while the nickel residue is higher. This is because the twin crystal structure can significantly improve the mechanical properties and acid corrosion resistance of the nickel layer. The twin crystal structure increases the number of grain boundaries, improving the strength and toughness of the nickel layer, and also increasing the barrier ability to acid corrosion media. Without the twin crystal structure, the nickel layer is more vulnerable to environmental factors, resulting in a decline in various properties.

[0133] The main difference between Comparative Example 2 and Example 1 lies in the current density and electroplating time during the preparation of the electroplated nickel layer, resulting in the electroplated nickel layer not obtaining an island-like columnar crystal structure, and the interface between the electroplated nickel layer and the electroplated chromium layer being linear. As can be seen from Table 2, this difference leads to the acid resistance and alkali resistance of Comparative Example 2 being lower than those of Example 1. At the same time, the tensile strength and peel strength of Comparative Example 2 are also lower, while the nickel residue is higher. This is because the island-like columnar crystal structure can significantly improve the mechanical properties and corrosion resistance of the nickel layer. The island-like columnar crystal structure provides a larger specific surface area and more grain boundaries, enhancing the strength and toughness of the nickel layer. In addition, the non-linear interface increases the bonding force between the nickel layer and the chromium layer, improving the overall performance.

[0134] The main difference between Comparative Example 3 and Example 1 is the amount of 3-(trimethoxysilyl)-1-propanethiol added to the photosensitive resin layer. As can be seen from Table 2, this difference leads to a slight decrease in the water resistance, acid resistance, oil resistance and alkali resistance of Comparative Example 3 compared with Example 1. The tensile strength and peel strength of Comparative Example 3 are also slightly lower, while the nickel residue is slightly higher. This is because the amount of 3-(trimethoxysilyl)-1-propanethiol affects the content of mercapto groups in the resin. An appropriate content of mercapto groups can significantly improve the bonding force between the resin and the nickel layer, enhancing the overall performance. An excessive content of mercapto groups may cause changes in the resin network structure, affecting its mechanical properties and corrosion resistance.

[0135] In summary, Example 1 is superior to each comparative example in all performance indicators. This shows that by optimizing the structure of the electroplated nickel layer (such as obtaining a twin crystal structure by adding rare earth elements and obtaining an island-like columnar crystal structure by adjusting electroplating parameters), the comprehensive performance of the coating can be significantly improved. These optimization measures work together to improve the corrosion resistance, mechanical strength and bonding force of the coating, while reducing the nickel residue, thus obtaining more excellent performance.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that any equivalent structural transformation made under the concept of the present invention using the content of the specification and drawings of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. An acid and alkali resistant high-strength composite printing nickel screen, characterized in that, It includes a printed nickel screen substrate, and an electroplated nickel layer, an electroplated chromium layer and a photosensitive resin layer are sequentially arranged on the surface of the printed nickel screen substrate from inside to outside; The photosensitive resin layer is obtained by a thiol-ene click chemical reaction of a polyurethane-acrylate prepolymer and a mercapto silicone resin; The preparation method of the mercapto silicone resin includes the following steps. In terms of parts by weight, add 150-170 parts of dimethyldiethoxysilane, 75-85 parts of methyltrimethoxysilane, 180-200 parts of 3-(trimethoxysilyl)-1-propanethiol and 210-230 parts of toluene into a three-necked flask, stir and mix and heat to 45-55 °C, then dropwise add 150-170 parts of hydrochloric acid with a mass fraction of 5-10%, and then stir the obtained mixture at 55-65 °C for 240-360 min, then let it stand for layering, separate the aqueous phase and the organic phase, retain the organic phase, then wash the organic phase to neutral, and finally carry out vacuum concentration treatment at 110-120 °C and 120-130 mmHg for 120-240 min to remove the solvent and volatile by-products in the organic phase, and obtain a transparent mercapto silicone resin; Among them, the electroplated nickel layer contains a columnar crystal structure with island growth, and the average diameter of the columnar crystal structure is 50-150 nm; the electroplated nickel layer also contains a twin crystal structure; The interface between the electroplated nickel layer and the electroplated chromium layer is wavy.

2. The acid and alkali resistant high-strength composite printing nickel screen according to claim 1, wherein, The thickness of the printed nickel screen substrate is 40-50 μm, and the thickness of the electroplated nickel layer is 60-80 μm; The thickness of the electroplated chromium layer is 20-45 μm; the thickness of the photosensitive resin layer is 15-35 μm.

3. The acid and alkali resistant high-strength composite printing nickel screen according to claim 1, characterized in that, The preparation method of the photosensitive resin layer comprises the following steps: by weight, 20-45 parts of polyurethane-acrylate prepolymer, 0.5-2.0 parts of 1-hydroxycyclohexyl phenyl ketone and 15-30 parts of mercapto silicone resin are mixed at a rotation speed of 2000-3000 r / min for 30-60 min, then coated on the electroplated chromium layer, and then cured under ultraviolet light with a wavelength of 365 nm and a radiation intensity of 8.0-10.5 mW·cm −2 for 30-45 s, and the photosensitive resin layer is obtained after complete curing.

4. The acid- and alkali-resistant high-strength composite printing nickel screen according to claim 1 or 3, characterized in that, The preparation method of the polyurethane-acrylate prepolymer includes the following steps: In terms of parts by weight, add 15-25 parts of polytetramethylene ether glycol, 0.20-0.30 parts of trimethylolpropane, 0.015-0.025 parts of dibutyltin dilaurate into a three-necked flask, stir and mix and heat to 55-65 °C, then dropwise add 5.0-9.0 parts of isophorone diisocyanate, and then continuously stir the obtained mixture at 55-65 °C for 60-120 min, then add 4.0-8.0 parts of hydroxypropyl acrylate, continue to stir for 30-45 min, and finally treat at 110-120 °C and 120-130 mmHg for 60-120 min to remove the raw material residues in the obtained mixture, and generate a transparent viscous polyurethane-acrylate prepolymer.

5. The preparation method of an acid and alkali resistant high-strength composite printing nickel screen according to claim 4, characterized in that, It includes the following steps: S1. Put the core mold into the first nickel electroplating solution for nickel plating, separate the nickel screen formed by nickel plating from the core mold, and obtain a printed nickel screen substrate; S2. Then put the printed nickel screen substrate into the second nickel electroplating solution for nickel plating, so that the surface of the printed nickel screen substrate is covered with an electroplated nickel layer; Then place it in a chromium electroplating solution for chromium plating, so that the surface of the electroplated nickel layer is covered with an electroplated chromium layer; The composition of the second nickel plating bath includes: nickel sulfate 140 - 150 g / L, nickel chloride 38 - 42 g / L, boric acid 32 - 36 g / L, rare earth additive 0.5 - 3.5 g / L, 1,4 - butynediol 0.26 - 0.30 g / L, sodium dodecyl sulfate 0.08 - 0.12 g / L, sodium thiazolinyl dithiopropane sulfonate 60 - 100 mg / L, and the balance is water; the rare earth additive is a composition of one or both of lanthanum oxide and lanthanum chloride; The process parameters for nickel plating are as follows: the temperature is 35 - 45 °C, the current density is 8 - 12 A / dm 2 , and the electroplating time is 120 - 240 min; S3. Prepare a photosensitive resin layer on the surface of the chromium plating layer.

6. The preparation method of an acid and alkali resistant high-strength composite printing nickel screen according to claim 5, characterized in that, In the step S1, the composition of the first nickel plating bath includes: nickel sulfate 140 - 150 g / L, nickel chloride 38 - 42 g / L, boric acid 32 - 36 g / L, 1,4 - butynediol 0.26 - 0.30 g / L, sodium dodecyl sulfate 0.08 - 0.12 g / L, sodium thiazolinyl dithiopropane sulfonate 60 - 100 mg / L, and the balance is water.

7. The preparation method of an acid- and alkali-resistant high-strength composite printing nickel screen according to claim 5, characterized in that, In the step S1, the process parameters for nickel plating are as follows: the temperature is 40 - 45 °C, the current density is 2.5 - 3.5 A / dm 2 , and the electroplating time is 35 - 45 min.

8. The preparation method of an acid and alkali resistant high-strength composite printing nickel screen according to claim 5, characterized in that, In the step S2, the composition of the chromium plating bath includes: chromium sulfate 0.4 - 0.8 mol / L, formic acid 0.7 - 1.2 mol / L, ammonium chloride 0.8 - 1.2 mol / L, potassium chloride 0.8 - 1.2 mol / L, polyethylene glycol 0.02 - 0.07 mol / L, and the balance is water; The technological parameters of chrome plating are as follows: the temperature is 55 - 65 °C, the current density is 65 - 75 A / dm 2 , and the electroplating time is 40 - 70 min.

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