Etching process of screen cloth for silk-screen printing plate

Abstract

The invention discloses an etching process of screen cloth for a silk-screen printing plate, and relates to the technical field of silk-screen printing plates. An etching process of screen cloth for a silk-screen printing plate comprises the following steps that S1, a silk screen and a screen frame are taken according to the printing requirement, cleaned and dried, the cleaned silk screen is tightened on the screen frame, and the tension is adjusted to be 20-25 N; s2, uniformly coating the surface of the silk screen with a photosensitive adhesive, and drying to obtain a photosensitive film; s3, a positive image negative film is manufactured according to printing requirements, the positive image negative film is attached to the photosensitive film, exposure is carried out under iodine gallium lamplight, and then the positive image negative film and the photosensitive film are put into water to be soaked, cleaned and dried to obtain a developing screen printing plate; s4, checking the developing screen printing plate, repairing the missing part, and drying after repairing; and S5, coating a curing agent on the surface of the repaired screen printing plate, and performing curing treatment to obtain the screen cloth. According to the invention, the resolution ratio of the prepared screen cloth is higher by preparing the photo-sensitive resist with good thermal stability and good developing effect.

Description

Technical Field

[0001] The present invention relates to the technical field of screen printing stencils, and specifically to an etching process for the screen cloth used in screen printing stencils. Background Art

[0002] Screen printing is an ancient and widely used printing technique. The specific production method is to stretch the screen tightly on the screen frame, then coat the photosensitive glue on the screen, attach the designed pattern negative to the screen coated with the photosensitive glue and perform exposure. The photosensitive glue in the exposed part undergoes a photochemical reaction and solidifies, and the unexposed part is removed by rinsing with the developer, thus obtaining the screen printing stencil.

[0003] Patent CN202310248841.3 discloses an etching process for screen cloth, a screen printing stencil and its application. Monomers are introduced into the polymer emulsion and diazo photosensitizer to make them undergo a crosslinking reaction to form an interpenetrating network structure, enhancing the crosslinking strength of the photosensitive film, thereby improving its water resistance, solvent resistance and weather resistance to obtain higher resolution.

[0004] For the plate-making process, the most important process lies in the preparation of the photosensitive glue, which requires good thermal stability and resolution of the photosensitive glue. Therefore, we propose an etching process for the screen cloth used in screen printing stencils. Summary of the Invention

[0005] The purpose of the present invention is to provide an etching process for the screen cloth used in screen printing stencils to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: An etching process for the screen cloth used in screen printing stencils, comprising the following steps:

[0007] S1: Take the screen and the screen frame according to the printing requirements, clean and dry them, stretch the cleaned screen tightly on the screen frame, and adjust the tension to 20 N - 25 N;

[0008] S2: Uniformly coat the photosensitive glue on the surface of the screen and dry it to obtain a photosensitive film;

[0009] S3: Make a positive film negative according to the printing requirements, attach the positive film negative to the photosensitive film, perform exposure under an iodine gallium lamp, then soak and clean it in water, and dry it to obtain a developed stencil;

[0010] S4: Check the developed stencil, repair the missing parts, and dry it after repair;

[0011] S5: Apply a curing agent on the surface of the repaired stencil and perform a curing treatment to obtain the screen cloth.

[0012] Further, in S1, the coating thickness of the photosensitive glue is 0.01 mm - 0.06 mm.

[0013] Further, in S1, the wire mesh is one of stainless steel wire mesh, polyester wire mesh, and nylon wire mesh.

[0014] Further, in S2, the drying temperature is 40°C to 50°C.

[0015] Further, in S3, the process conditions for exposure are: exposure power 1000W to 1300W, lamp distance 0.5m to 1.5m, and time 20s to 60s.

[0016] Further, in S5, the process conditions for curing treatment are: temperature 45°C to 55°C, and time 30min to 60min.

[0017] Further, the curing agent is one or a mixture of two of polyetheramine and hexamethylenediamine.

[0018] Further, in S2, the photosensitive glue is prepared by the following process:

[0019] Step (1): Mix dopamine polymer, diazo resin, and water, then add polyvinyl alcohol emulsion, stir for 5min to 15min, and place in the dark at room temperature for 30min to 60min to obtain mixture A;

[0020] Step (2): Add fluorinated acrylic monomer, functional acrylic monomer, and initiator to mixture A, and stir evenly in the dark at room temperature to obtain the photosensitive glue.

[0021] Further, in step (1), the mass ratio of dopamine polymer, diazo resin, water, and polyvinyl alcohol emulsion is 10:(0.4 - 0.8):(0.5 - 1):(80 - 100).

[0022] Further, in step (2), the mass ratio of mixture A, fluorinated acrylic monomer, functional acrylic monomer, and initiator is 1:(0.5 - 1):(0.3 - 0.7):(0.04 - 0.08).

[0023] Further, in step (2), the fluorinated acrylic monomer is one or a mixture of several of hexafluoroisopropyl methacrylate, trifluoroethyl methacrylate, dodecafluoroheptyl methacrylate, and tridecafluorooctyl methacrylate;

[0024] The functional acrylic monomer is one or a mixture of several of 2-hydroxyethyl methacrylate, diacetone acrylamide, N-hydroxymethyl acrylamide, and ethyl acetoacetate methacrylate.

[0025] Further, the dopamine polymer described in step (1) is prepared by the following process:

[0026] Glycidyl methacrylate was mixed with N,N-dimethylformamide and stirred until dissolved. 6-Hydroxydopamine hydrochloride was added, and vacuum-argon filling operation was carried out. The operation was repeated 3 times, followed by heating reaction to obtain a reaction solution. The reaction solution was dropped into a hydrochloric acid solution with a concentration of 1 mol / L for precipitation, centrifuged, the precipitate was collected, washed, and dried for 24 h to obtain dopamine polymer.

[0027] Furthermore, the ratio of glycidyl methacrylate, N,N-dimethylformamide to 6-hydroxydopamine hydrochloride is (0.05 - 0.1) g : (4 - 8) mL : (0.1 - 0.3) g.

[0028] Furthermore, the process conditions for the heating reaction are: temperature 70 °C - 90 °C, time 12 h - 24 h.

[0029] Furthermore, the process conditions for centrifugation are: rotation speed 6000 r / min - 8000 r / min, time 3 min - 5 min.

[0030] In the above technical solution, etching was carried out through processes such as exposure, development, immersion, and cleaning to obtain a mesh cloth. By preparing a photosensitive glue with good thermal stability and good development effect, the resolution of the obtained mesh cloth is higher;

[0031] First, a nucleophilic ring-opening reaction occurred between the epoxy group of glycidyl methacrylate and the amino group of 6-hydroxydopamine hydrochloride to generate a dopamine polymer containing double bonds and hydroxyl groups. Since the diazo resin will decompose to generate diazo resin free radicals at room temperature or under light, if directly mixed with polyvinyl alcohol emulsion, the diazo resin free radicals react with the hydroxyl groups in the polyvinyl alcohol emulsion, increasing the viscosity and reducing the photochemical reaction, resulting in difficult screen plate rinsing and development. However, the dopamine polymer contains hydroxyl groups. Mixing it with the diazo resin first, the diazo resin free radicals react with the hydroxyl groups of the dopamine polymer first, inhibiting the reaction between the diazo resin free radicals and the polyvinyl alcohol emulsion, prolonging the shelf life of the photosensitive glue, and improving the thermal stability of the photosensitive glue. The developed photosensitive film formed after drying has a good development effect;

[0032] Mixture A contains double bonds and is mixed with a fluorinated acrylic monomer, a functional acrylic monomer, and an initiator to undergo a polymerization reaction to form a crosslinked network, enhancing the solvent resistance and weather resistance of the photosensitive film. The functional acrylic monomer has the characteristic of slow crosslinking speed, preventing the crosslinking degree between the photosensitive agent layers from being too high during the drying process due to too fast crosslinking speed, which affects the adhesion strength between the photosensitive glue and the silk screen. The fluorinated acrylic monomer contains a fluorine chain segment with hydrophobic properties, endowing the photosensitive glue with certain water resistance. The fluorine chain segment also has a strong electronegativity, which can further optimize the structure of the crosslinked network and enhance the photosensitivity of free radicals, thereby improving the edge clarity of the photosensitive film on the silk screen and making the screen plate have higher precision.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. First, glycidyl methacrylate reacts with 6-hydroxydopamine hydrochloride to generate a dopamine polymer containing double bonds and hydroxyl groups, which is then mixed with a diazo resin. First, the hydroxyl groups react with the diazo resin free radicals, and then it is mixed with a polyvinyl alcohol emulsion, which can inhibit the reaction between the diazo resin free radicals and the polyvinyl alcohol emulsion, prevent the viscosity from being too high and affecting the photochemical reaction. To a certain extent, the shelf life of the photosensitive glue is extended, the thermal stability of the photosensitive glue is improved, and the developed effect of the photosensitive film formed after drying is good.

[0035] 2. Through the polymerization reaction of the double bonds in mixture A with fluorinated acrylic monomers, functional acrylic monomers, and initiators, a cross-linked network is formed to enhance the solvent resistance and weather resistance of the photosensitive film; taking advantage of the slow cross-linking speed of functional acrylic monomers, it is prevented that during the drying process of the photosensitizer, due to too fast cross-linking speed, the cross-linking degree between the glue layers is too high, affecting the adhesion strength between the photosensitive glue and the screen. The fluorinated acrylic monomer contains a fluorine chain segment, which has hydrophobic properties and imparts a certain degree of water resistance to the photosensitive glue. The fluorine chain segment also has a strong electronegativity, which can further optimize the structure of the cross-linked network and enhance the photosensitivity of free radicals, thereby improving the edge clarity of the photosensitive film on the screen and making the screen plate have higher precision. Specific Embodiments

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] In the following specific embodiments,

[0038] Stainless steel wire mesh, 400 meshes, pore diameter 1.5 mm, wire diameter 0.025 mm, sourced from Anping Hongda Hardware Wire Mesh Factory;

[0039] Glycidyl methacrylate, CAS number 106-91-2, sourced from Jinan Century Tongda Chemical Co., Ltd.;

[0040] N,N-dimethylformamide, CAS number 68-12-2, sourced from Shandong Junlong Chemical Co., Ltd.;

[0041] 6-Hydroxydopamine hydrochloride, CAS number 28094-15-7, sourced from Qiyuan (Guangdong) Pharmaceutical Chemical Co., Ltd.;

[0042] Hydrochloric acid solution, product number R27801, sourced from Yuanye Bio;

[0043] Polyvinyl alcohol emulsion, model MY-100, sourced from Dongguan Mingyu New Materials Co., Ltd.;

[0044] Diazo resin, model SP-1400GK, sourced from Shenyang China Printing Machinery Co., Ltd.;

[0045] Hexafluoroisopropyl methacrylate, CAS No. 3063-94-3, sourced from Hubei Xingyan New Materials Technology Co., Ltd.;

[0046] 2-Hydroxyethyl methacrylate, CAS No. 868-77-9, sourced from Shandong Langcheng Chemical Co., Ltd.;

[0047] 2,2'-Azobis(2-methylpropionitrile), CAS No. 78-67-1, sourced from Shandong Taixi Chemical Co., Ltd.;

[0048] Polyetheramine, model D4000, sourced from Shandong Tonglan Chemical Co., Ltd.

[0049] Example 1: An etching process for the screen cloth used in screen printing, comprising the following steps:

[0050] (1) Preparation of photosensitive glue:

[0051] Mix glycidyl methacrylate with N,N-dimethylformamide, stir until dissolved, add 6-hydroxydopamine hydrochloride, perform vacuum-argon filling operation, repeat the operation 3 times, heat and react to obtain a reaction solution, drop the reaction solution into a hydrochloric acid solution with a concentration of 1 mol / L for precipitation, centrifuge, collect the precipitate, wash, and dry for 24 h to obtain dopamine polymer; the ratio of glycidyl methacrylate, N,N-dimethylformamide to 6-hydroxydopamine hydrochloride is 0.1 g: 8 mL: 0.3 g; the process conditions for heating reaction are: temperature 90 °C, time 24 h; the process conditions for centrifugation are: rotation speed 8000 r / min, time 5 min;

[0052] Step (1): Mix dopamine polymer, diazo resin and water, then add polyvinyl alcohol emulsion, stir for 15 min, and place in the dark at room temperature for 60 min to obtain mixture A; Step (2): Add hexafluoroisopropyl methacrylate, 2-hydroxyethyl methacrylate and initiator to mixture A, stir evenly in the dark at room temperature to obtain photosensitive glue; in step (1), the mass ratio of dopamine polymer, diazo resin, water and polyvinyl alcohol emulsion is 10: 0.8: 1: 100; in step (2), the mass ratio of mixture A, hexafluoroisopropyl methacrylate, 2-hydroxyethyl methacrylate and initiator is 1: 1: 0.7: 0.08;

[0053] (2) Preparation of screen cloth:

[0054] S1: Take the screen and the screen frame according to the printing requirements, clean, dry, stretch the cleaned screen tightly on the screen frame, and adjust the tension to 25 N; S2: Uniformly coat the photosensitive glue on the surface of the screen, and dry to obtain a photosensitive film; S3: Make a positive film negative according to the printing requirements, laminate the positive film negative with the photosensitive film, expose it under an iodine gallium lamp, then soak and clean it in water, and dry it to obtain a developed screen plate after drying; S4: Inspect the developed screen plate, repair the missing parts, and dry it after repair; S5: Apply polyetheramine on the surface of the repaired screen plate and perform a curing treatment to obtain a screen cloth; In S1, the coating thickness of the photosensitive glue is 0.06 mm; In S2, the drying temperature is 50 °C; In S3, the process conditions for exposure are: exposure power 1300 W, lamp distance 1.5 m, time 60 s; In S5, the process conditions for the curing treatment are: temperature 55 °C, time 60 min.

[0055] Example 2: An etching process for the screen cloth used in the silk screen plate, including the following steps:

[0056] (1) Preparation of the photosensitive glue:

[0057] Mix glycidyl methacrylate and N,N-dimethylformamide, stir until dissolved, add 6-hydroxydopamine hydrochloride, perform a vacuum-argon filling operation, repeat the operation 3 times, heat and react to obtain a reaction solution, drop the reaction solution into a hydrochloric acid solution with a concentration of 1 mol / L for precipitation, centrifuge, collect the precipitate, wash, and dry for 24 h to obtain a dopamine polymer; The ratio of glycidyl methacrylate, N,N-dimethylformamide to 6-hydroxydopamine hydrochloride is 0.07 g: 6 mL: 0.2 g; The process conditions for the heating reaction are: temperature 80 °C, time 18 h; The process conditions for centrifugation are: rotation speed 7000 r / min, time 4 min;

[0058] Step (1): Mix the dopamine polymer, diazo resin and water, then add polyvinyl alcohol emulsion, stir for 10 min, and place it in the dark at room temperature for 45 min to obtain mixture A; Step (2): Add hexafluoroisopropyl methacrylate, 2-hydroxyethyl methacrylate and an initiator to mixture A, and stir evenly in the dark at room temperature to obtain the photosensitive glue; In step (1), the mass ratio of the dopamine polymer, diazo resin, water and polyvinyl alcohol emulsion is 10: 0.6: 0.7: 90; In step (2), the mass ratio of mixture A, hexafluoroisopropyl methacrylate, 2-hydroxyethyl methacrylate and the initiator is 1: 0.7: 0.5: 0.06;

[0059] (2) Preparation of the screen cloth:

[0060] S1: Take the silk screen and the screen frame according to the printing requirements, clean, dry, stretch the cleaned silk screen tightly on the screen frame, and adjust the tension to 23 N; S2: Uniformly coat the photosensitive glue on the surface of the silk screen, and dry it to obtain a photosensitive film; S3: Make a positive film negative according to the printing requirements, laminate the positive film negative with the photosensitive film, expose it under an iodine gallium lamp, then soak and clean it in water, and dry it to obtain a developed screen plate;

[0061] S4: Inspect the developed screen plate, repair the missing parts, and dry it after repair; S5: Apply polyetheramine on the surface of the repaired screen plate and perform a curing treatment to obtain a screen cloth; In S1, the coating thickness of the photosensitive glue is 0.04 mm; In S2, the drying temperature is 45 °C; In S3, the process conditions for exposure are: exposure power 1200 W, lamp distance 1.0 m, time 40 s; In S5, the process conditions for the curing treatment are: temperature 50 °C, time 45 min.

[0062] Example 3: An etching process for a screen cloth used for a silk screen printing plate, comprising the following steps:

[0063] (1) Preparation of the photosensitive glue:

[0064] Mix glycidyl methacrylate and N,N-dimethylformamide, stir until dissolved, add 6-hydroxydopamine hydrochloride, perform a vacuum-argon filling operation, repeat the operation 3 times, heat and react to obtain a reaction solution, drop the reaction solution into a hydrochloric acid solution with a concentration of 1 mol / L for precipitation, centrifuge, collect the precipitate, wash, and dry for 24 h to obtain a dopamine polymer; The ratio of glycidyl methacrylate, N,N-dimethylformamide to 6-hydroxydopamine hydrochloride is 0.1 g: 8 mL: 0.3 g; The process conditions for the heating reaction are: temperature 90 °C, time 24 h; The process conditions for centrifugation are: rotation speed 8000 r / min, time 5 min;

[0065] Step (1): Mix the dopamine polymer, diazo resin and water, then add polyvinyl alcohol emulsion, stir for 15 min, and place it in the dark at room temperature for 60 min to obtain mixture A; Step (2): Add hexafluoroisopropyl methacrylate, 2-hydroxyethyl methacrylate and an initiator to mixture A, and stir evenly in the dark at room temperature to obtain the photosensitive glue; In step (1), the mass ratio of the dopamine polymer, diazo resin, water and polyvinyl alcohol emulsion is 10: 0.8: 1: 100; In step (2), the mass ratio of mixture A, hexafluoroisopropyl methacrylate, 2-hydroxyethyl methacrylate and the initiator is 1: 1: 0.7: 0.08;

[0066] (2) Preparation of the screen cloth:

[0067] S1: Select a screen mesh and a screen frame according to the printing requirements, clean, dry, stretch the cleaned screen mesh tightly on the screen frame, and adjust the tension to 25 N; S2: Uniformly coat the photosensitive glue on the surface of the screen mesh, and dry it to obtain a photosensitive film; S3: Produce a positive film negative according to the printing requirements, laminate the positive film negative with the photosensitive film, expose it under an iodine gallium lamp, then soak and clean it in water, and dry it to obtain a developed screen plate; S4: Inspect the developed screen plate, repair the missing parts, and dry it after repair; S5: Apply polyetheramine on the surface of the repaired screen plate and carry out curing treatment to obtain a screen cloth; In S1, the coating thickness of the photosensitive glue is 0.06 mm; In S2, the drying temperature is 50 °C; In S3, the process conditions for exposure are: exposure power 1300 W, lamp distance 1.5 m, time 60 s; In S5, the process conditions for curing treatment are: temperature 45 °C, time 30 min.

[0068] Comparative Example 1: Taking Example 1 as a comparison, when preparing the photosensitive glue, dopamine polymer is not added, and the other conditions remain unchanged. An etching process for the screen cloth used in a silk screen printing plate includes the following steps:

[0069] (1) Preparation of the photosensitive glue:

[0070] Mix diazo resin, water and polyvinyl alcohol emulsion, stir for 15 min, add hexafluoroisopropyl methacrylate, hydroxyethyl methacrylate and initiator, and stir evenly in the dark at room temperature to obtain the photosensitive glue; The mass ratio of diazo resin, water and polyvinyl alcohol emulsion is 0.8:1:100.

[0071] (2) Preparation of the screen cloth:

[0072] S1: Select a screen mesh and a screen frame according to the printing requirements, clean, dry, stretch the cleaned screen mesh tightly on the screen frame, and adjust the tension to 25 N; S2: Uniformly coat the photosensitive glue on the surface of the screen mesh, and dry it to obtain a photosensitive film; S3: Produce a positive film negative according to the printing requirements, laminate the positive film negative with the photosensitive film, expose it under an iodine gallium lamp, then soak and clean it in water, and dry it to obtain a developed screen plate; S4: Inspect the developed screen plate, repair the missing parts, and dry it after repair; S5: Apply polyetheramine on the surface of the repaired screen plate and carry out curing treatment to obtain a screen cloth; In S1, the coating thickness of the photosensitive glue is 0.06 mm; In S2, the drying temperature is 50 °C; In S3, the process conditions for exposure are: exposure power 1300 W, lamp distance 1.5 m, time 60 s; In S5, the process conditions for curing treatment are: temperature 55 °C, time 60 min.

[0073] Comparative Example 2: Taking Example 1 as a comparison, when preparing the photosensitive glue, hexafluoroisopropyl methacrylate and hydroxyethyl methacrylate are not added, and the other conditions remain unchanged. An etching process for the screen cloth used in a silk screen printing plate includes the following steps:

[0074] (1) Preparation of photosensitive glue:

[0075] Mix glycidyl methacrylate with N,N-dimethylformamide and stir until dissolved. Add 6-hydroxydopamine hydrochloride, perform vacuum-argon filling operation, repeat the operation 3 times, heat and react to obtain a reaction solution. Drop the reaction solution into a hydrochloric acid solution with a concentration of 1 mol / L for precipitation, centrifuge, collect the precipitate, wash, and dry for 24 h to obtain dopamine polymer; the ratio of glycidyl methacrylate, N,N-dimethylformamide to 6-hydroxydopamine hydrochloride is 0.1 g: 8 mL: 0.3 g; the technological conditions for heating reaction are: temperature 90 °C, time 24 h; the technological conditions for centrifugation are: rotation speed 8000 r / min, time 5 min;

[0076] Step (1): Mix dopamine polymer, diazo resin and water, then add polyvinyl alcohol emulsion and stir for 15 min, and place in the dark at room temperature for 60 min to obtain mixture A; Step (2): Add an initiator to mixture A and stir evenly in the dark at room temperature to obtain photosensitive glue; in step (1), the mass ratio of dopamine polymer, diazo resin, water and polyvinyl alcohol emulsion is 10: 0.8: 1: 100; in step (2), the mass ratio of mixture A to the initiator is 1: 0.08;

[0077] (2) Preparation of screen cloth:

[0078] S1: Take a silk screen and a screen frame according to printing requirements, clean, dry, stretch the cleaned silk screen on the screen frame, and adjust the tension to 25 N; S2: Uniformly coat the photosensitive glue on the surface of the silk screen and dry to obtain a photosensitive film; S3: Make a positive film negative according to printing requirements, attach the positive film negative to the photosensitive film, expose under an iodine gallium lamp, then soak and wash in water, and dry to obtain a developed screen plate; S4: Check the developed screen plate, repair the missing parts, and dry after repair; S5: Apply polyetheramine on the surface of the repaired screen plate and perform curing treatment to obtain screen cloth; in S1, the coating thickness of the photosensitive glue is 0.06 mm; in S2, the drying temperature is 50 °C; in S3, the technological conditions for exposure are: exposure power 1300 W, lamp distance 1.5 m, time 60 s; in S5, the technological conditions for curing treatment are: temperature 55 °C, time 60 min.

[0079] Comparative Example 3: Taking Example 1 as a comparison, neither 6-hydroxydopamine hydrochloride is used nor hexafluoroisopropyl methacrylate and 2-hydroxyethyl methacrylate are added, and the other conditions remain unchanged.

[0080] Experiment:

[0081] Development effect test: Take the photosensitive adhesives obtained in Examples 1 to 3 and Comparative Examples 1 to 3, dry them at 50 °C to obtain photosensitive films, laminate them with positive film negatives, expose them under a 1300 W iodine gallium lamp, then rinse and develop, observe the development effect and water development fastness, and record them;

[0082] Resolution test: Take the screen fabrics obtained in Examples 1 to 3 and Comparative Examples 1 to 3, select alumina ceramics as the substrate, print patterns with different resolutions on the substrate, observe the patterns, and test the minimum resolution at which the patterns are complete;

[0083] The following table shows the test results of the development effect, water development fastness and resolution of the photosensitive films;

[0084] Development effect Water development fastness Resolution / μm Example 1 Good development effect Normal 110 Example 2 Normal development Normal 150 Example 3 Normal development Normal 200 Comparative example 1 Poor development effect Too high fastness 230 Comparative example 2 Poor development effect Relatively large fastness 260 Comparative example 3 Poor development effect Too high fastness 350

[0085] From the data in the above table, the following conclusions can be clearly drawn:

[0086] Examples 1 to 3 are compared with the photosensitive films in Comparative Examples 1 to 3. From the test results,

[0087] Compared with Example 1, in the preparation of the photosensitive adhesive in Comparative Example 1, dopamine polymer is not added, the development effect is poor, and the water development fastness is too high. This is because the dopamine polymer is first mixed with the polyvinyl alcohol emulsion, inhibiting the reaction between the diazo resin free radical and the polyvinyl alcohol emulsion, prolonging the shelf life of the photosensitive adhesive, and improving the thermal stability of the photosensitive adhesive. The photosensitive film formed after drying has a better development effect;

[0088] Compared with Example 1, in the preparation of the photosensitive adhesive in Comparative Example 2, fluorinated acrylic monomers and functional acrylic monomers are not added, the development effect is poor, the water development fastness is on the high side, and the resolution drops significantly. This is because the functional acrylic monomers have the characteristic of slow crosslinking speed, which can prevent the crosslinking speed of the photosensitizer from being too fast during drying, resulting in too high crosslinking degree between the adhesive layers and affecting the adhesion strength between the photosensitive adhesive and the screen. The fluorine chain segment also has strong electronegativity, which can further optimize the structure of the crosslinking network and enhance the photosensitivity of the free radicals, thereby improving the edge clarity of the photosensitive film on the screen and making the screen plate have higher precision;

[0089] Compared with Example 1, in Comparative Example 3, neither 6-hydroxy dopamine hydrochloride nor fluorinated acrylic monomers and functional acrylic monomers are used, indicating that the settings of the process and the materials used in this application can promote the improvement of the thermal stability of the photosensitive adhesive and the development effect and resolution of the screen plate.

[0090] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention.

Claims

1. An etching process for screen cloth used in silk screen printing plates, characterized in that: It includes the following steps: S1: Take the screen and the screen frame according to the printing requirements, clean, dry, stretch the cleaned screen tightly on the screen frame, and adjust the tension to 20N - 25N; S2: Uniformly coat the photosensitive glue on the surface of the screen, and dry to obtain a photosensitive film; S3: Make a positive film negative according to the printing requirements, laminate the positive film negative with the photosensitive film, expose it under an iodine gallium lamp, then soak and wash it in water, and dry to obtain a developed screen plate; S4: Inspect the developed screen plate and repair the missing parts; S5: Apply a curing agent on the surface of the repaired screen plate, and perform a curing treatment to obtain a screen cloth; The photosensitive glue includes the following components: dopamine polymer, diazo resin, polyvinyl alcohol emulsion, fluorinated acrylic monomer, functional acrylic monomer.

2. The etching process of the screen cloth for the silk screen printing stencil according to claim 1, characterized in that: In S1, the coating thickness of the photosensitive glue is 0.01mm - 0.06mm.

3. The etching process of the screen cloth for the silk screen printing plate according to claim 1, characterized in that: In S3, the process conditions for exposure are: exposure power 1000W - 1300W, lamp distance 0.5m - 1.5m, time 20s - 60s.

4. An etching process for a screen cloth used in a silk screen printing stencil, characterized in that: The photosensitive glue is prepared by the following process: Step (1): Mix the dopamine polymer, diazo resin and water, then add the polyvinyl alcohol emulsion, stir for 5min - 15min, and place it in the dark at room temperature for 30min - 60min to obtain mixture A; Step (2): Add the fluorinated acrylic monomer, functional acrylic monomer and initiator to mixture A, and stir evenly in the dark at room temperature to obtain the photosensitive glue.

5. The etching process of the screen cloth for the silk screen printing stencil according to claim 4, characterized in that: In step (1), the dopamine polymer is prepared by the following process: Mix glycidyl methacrylate with N,N - dimethylformamide, stir until dissolved, add 6 - hydroxydopamine hydrochloride, perform a vacuum - argon filling operation, repeat the operation 3 times, heat and react to obtain a reaction solution, drop the reaction solution into a hydrochloric acid solution with a concentration of 1mol / L for precipitation, centrifuge, collect the precipitate, wash, and dry for 24h to obtain the dopamine polymer.

6. The etching process of the screen cloth for the silk screen printing stencil according to claim 5, characterized in that: The ratio of glycidyl methacrylate, N,N - dimethylformamide to 6 - hydroxydopamine hydrochloride is (0.05 - 0.1)g:(4 - 8)mL:(0.1 - 0.3)g.

7. An etching process for a screen cloth used in a silk screen printing stencil, characterized in that: The process conditions for centrifugation are: rotation speed 6000r / min - 8000r / min, time 3min - 5min.

8. An etching process for the screen cloth used in the silk screen printing stencil, characterized in that: In step (1), the mass ratio of the dopamine polymer, diazo resin, water and polyvinyl alcohol emulsion is 10:(0.4 - 0.8):(0.5 - 1):(80 - 100).

9. An etching process for a screen cloth used in a silk screen printing stencil, characterized in that: In step (2), the mass ratio of mixture A, fluorinated acrylic monomer, functional acrylic monomer and initiator is 1:(0.5 - 1):(0.3 - 0.7):(0.04 - 0.08).

10. The etching process of the screen cloth for the silk screen printing stencil according to claim 4, characterized in that: In step (2), the fluorinated acrylic monomer is one or a mixture of hexafluoroisopropyl methacrylate, trifluoroethyl methacrylate, dodecafluoroheptyl methacrylate, tridecafluorooctyl methacrylate; The functional acrylic monomer is one or a mixture of 2 - hydroxyethyl methacrylate, diacetone acrylamide, N - hydroxymethyl acrylamide, ethyl acetoacetate methacrylate.