Method for manufacturing uv inkjet screen printing plate and anchoring enhancement method thereof

Abstract

The application discloses a kind of UV spray drawing silk screen printing plate and its anchoring enhancement method, belong to silk screen printing plate making technical field.Aluminum or wood screen frame is bound nylon screen into blank silk screen empty plate, and single-sided adhesive is pasted on printing surface, and the pattern to be printed is mirror-inverted to obtain reverse image, UV ink is sprayed on adhesive surface using UV flatbed printer to solidify, adhesive base film is torn off to make inkjet area remain adhesive sealing, non-inkjet area screen hole is open, then residual adhesive is cleaned using acetone, toluene and xylene, and silk screen printing plate is obtained.For the problem of UV ink anchoring not firm, the application also provides an anchoring enhancement method: through screen hole embedding, surface activation, double-layer spray drawing, low-stress adhesive tearing, interface protection cleaning five steps, ink-adhesive-screen ternary anchoring structure is formed on the printing surface of adhesive, the ink-adhesive peel strength is increased from 1.2 N / 25mm to 5.6 N / 25mm, and the retention rate of sealing area reaches 98.5%.The method eliminates film, photosensitive adhesive, exposure and water development process, and the plate is changed as the picture is changed, and a general UV flatbed machine can be used to implement the method, the plate making cycle is short, and the cost is low.The application also protects the UV spray drawing silk screen printing plate product prepared by the method.

Description

Summary of the Invention

[0001] The primary objective of this invention is to eliminate the steps of film, photosensitive emulsion, exposure, and water development, and to directly print a reverse screen printing image on a stretched blank frame using a general-purpose UV flatbed inkjet printer. The non-image mesh openings are temporarily sealed with adhesive, and after peeling off the film and washing off the adhesive with solvent, a screen printing stencil that can be printed immediately is obtained.

[0002] The second objective of this invention is to solve the problem of UV ink not being firmly anchored on the self-adhesive and mesh fabric in the above process. By combining mesh embedding, surface activation, multi-layer printing, low-stress adhesive peeling, and interface protection cleaning, a reliable ternary anchoring structure is formed between ink, adhesive, and mesh, which significantly improves the retention rate and peel strength of the sealing area. Technical Field

[0003] This invention relates to the field of screen printing plate making technology, specifically to a method for producing a screen printing stencil by directly printing reverse images onto a blank screen printing stencil with adhesive backing using a UV flatbed inkjet printer, followed by removing the film and cleaning the residual adhesive with organic solvents. The method also includes an anchoring enhancement technique. Background Technology

[0004] Traditional screen printing stencils are made using a photosensitive method: a photosensitive emulsion is coated onto a stretched nylon or stainless steel mesh frame, film is output, vacuum exposure is performed, and the uncured emulsion layer is then washed with water before drying to obtain the stencil. This process has the following drawbacks: First, it requires film output, a darkroom, and developing and washing, resulting in numerous steps, high water consumption, and a long cycle time. Second, pattern modifications require re-outputting and re-exposure of film, making it unsuitable for small-batch, multi-style, and rapid stencil changes. Third, the thickness of the photosensitive emulsion layer affects ink penetration, and fine lines / dots are prone to edge chipping during development.

[0005] There are two main types of existing digital plate-making solutions: The first is "laser printing of a mirror image on a self-adhesive film → double-sided screen application → UV adhesive coating and curing → peeling off the self-adhesive film to form the image". In essence, the UV adhesive is still used to fill the screen to form a film, and the self-adhesive film is only used as an ink-blocking mask. It relies on the laser printer to image on the self-adhesive film, rather than directly digitally printing on the screen. The second is to use a number of precision sprays of liquid UV ink / AB glue onto the dot matrix screen film and then heat shrinks and removes the screen. The equipment is a special spraying device, not a commercially available UV flatbed printer, and it does not remove the adhesive or use the self-adhesive film to temporarily protect the screen.

[0006] Furthermore, in the "adhesive labeling + UV inkjet printing" process, a long-standing technical challenge has been the "unsecured anchoring of UV ink on the screen." This is essentially a problem of overlapping ink-adhesive and adhesive-screen interfaces: the adhesive printing surface is mostly a low-energy PET / BOPP surface (approximately 38 dyne), making it prone to pinholes and poor adhesion of UV ink; simultaneously, if the ink layer merely floats on the adhesive surface without mechanically interlocking with the warp and weft nodes of the screen, stress during adhesive removal leads to ink layer peeling and edge breakage in the screen sealing area. Existing technologies neither reveal the overall process of directly printing reverse images on a blank screen using a general-purpose UV flatbed printer, nor provide a systematic solution for the coordinated anchoring of the aforementioned three interfaces (ink-adhesive-screen).

[0007] In summary, there is currently no complete process that directly uses a general-purpose UV flatbed inkjet printer to print a reverse image onto a blank screen printing plate and single-sided self-adhesive label, then removes the adhesive and washes away any remaining adhesive with organic solvent to obtain the screen printing plate, while ensuring reliable anchoring of the UV ink. This invention solves the aforementioned technical problems. Technical solution

[0008] A basic plate-making method for creating a UV inkjet screen printing stencil includes the following steps: S1 Preparation of blank screen printing stencil: Take an aluminum profile or wooden frame, and tighten and fix the nylon mesh or stainless steel mesh onto the frame to obtain a blank screen printing stencil with through holes. S2 Applying a self-adhesive layer: Apply a layer of single-sided self-adhesive film to the entire printing side of the blank screen printing board, with the adhesive side of the self-adhesive facing the nylon mesh, so that the mesh is temporarily sealed by the adhesive layer. S3 Image Inversion Processing: The image to be screen-printed is mirrored and inverted in the computer, and the output is a screen-printed reverse image, so that the image appears as a positive image when viewed from the ink scraping side of the screen after printing. S4 UV flatbed printing: Place the blank screen with the self-adhesive sticker on the UV flatbed printer workbench, print UV ink according to the reverse image and cure it, so that the UV ink is cured on the self-adhesive surface to form a reverse image anchoring layer. S5 Remove the self-adhesive: Peel the self-adhesive substrate from the mesh side, so that the self-adhesive in the non-ink-printed area is separated from the substrate and the mesh is opened. The self-adhesive in the ink-printed area is anchored to the mesh by UV ink to form a sealing layer. S6 Residual Adhesive Cleaning: Wipe both sides of the screen with one or more of the following solvents: acetone, toluene, and xylene to dissolve the residual adhesive residue and UV ink debris on the screen, resulting in a screen printing screen with closed mesh in non-image areas and open mesh in image areas.

[0009] Anchoring reinforcement method (independent scheme) As a second aspect of the present invention, an anchoring enhancement method is provided in the production of UV inkjet screen printing stencils, comprising: S1 Mesh Embedding: The self-adhesive film applied to the nylon mesh is hot-rolled at 60–80℃ to embed the adhesive layer into the mesh holes by 1 / 3–1 / 2 of the mesh thickness, forming a mechanical interlock between the adhesive and the mesh. S2 Surface Activation: The self-adhesive printing surface is corona-treated or plasma-treated until the surface energy is ≥48 mN / m, or a 1–2 μm UV adhesion promoter layer is pre-coated. S3 Multilayer Printing: Uses rigid polyurethane acrylate UV ink (containing 2–5% silane adhesion promoter), first pre-curing the base ink to 6–10 μm (300–400 mJ / cm²), then finally curing the main ink to a total thickness of 15–22 μm (800–1200 mJ / cm²). S4 Low-stress adhesive tearing: Before tearing, use hot air at 40–50℃ to sweep the adhesive surface, and tear it off from the non-image area to the image area at ≤30° and 50–100 mm / s. S5 Interface Protection Cleaning: First wipe with ethanol / isopropanol 1–2 times, then wipe with acetone. Wipe and dry immediately to protect the ternary anchoring structure.

[0010] The above five steps work together to form a ternary anchoring structure on the self-adhesive printing surface, consisting of "ink-adhesive chemical anchoring + adhesive-mesh mechanical interlocking + ink layer cohesion," thereby systematically solving the problem of weak anchoring. Beneficial effects

[0011] Beneficial effects 1. Without the need for film, photosensitive emulsion, exposure machine, and developing tank, plate making is reduced from several hours to tens of minutes; 2. Print directly from AI / CDR files; modifying the image is equivalent to modifying the design, suitable for small-batch customization; 3. It can be implemented with a general-purpose UV flatbed printer, resulting in low equipment costs; 4. Adhesive film is used as a temporary carrier, and UV ink is used as an "adhesive anchoring pattern". After peeling off the film, the residual adhesive is used to clean the mesh, and the fine lines can reach 0.2 mm. 5. After anchoring reinforcement, the ink-adhesive peel force is increased from about 1.2 N / 25mm to ≥5.0 N / 25mm, the retention rate of the sealing area is ≥95%, the sealing layer can withstand the ink scraping pressure, and the screen life is significantly extended. Attached Figure Description

[0012] Figure 1 A flowchart of the basic plate-making method of this invention; Figure 2 Diagram of the opening / closing state changes of the adhesive peeling logic mesh ( Figure 2 (a)–2(d) correspond to the four states of adhesive sealing, inkjet anchoring, adhesive removal and residue retention, and cleaning of finished product). Figure 3 Schematic diagram of the cross-section of a blank screen printing plate with self-adhesive labels; Figure 4 A schematic diagram of the cross-section before peeling off the adhesive after printing the reverse image; Figure 5 Schematic diagram of the cross-section of the finished screen after adhesive washing; Figure 6 Figure A shows the effect of self-adhesive surface treatment on surface energy and ink-adhesive peel force. Figure 7 The curve showing the effect of UV curing energy on anchoring strength (ink layer residue rate) (Figure B). Figure 8 The effect curve of UV ink layer thickness on the retention rate of the sealing area after peeling off the adhesive (Figure C). Figure 9 The cumulative improvement of the anchoring effect by various combinations of optimization measures (Figure D). Figure 10 Schematic diagram of the cross-section of the UV ink-self-adhesive-nylon mesh ternary anchoring structure (Figure E). Figure 11 Diagram of four-state changes in adhesive tearing logic (Figure F, appendix to the abstract).

[0013] The markings in the diagram mean: white squares = open mesh (ink permeation), gray squares = closed mesh (mesh sealing), black squares = UV inkjet printing area; the adhesive in the inkjet area is anchored by the UV ink and remains to form a sealing layer, while the adhesive in the non-inkjet area is peeled off with the base film, restoring the mesh's openness. Detailed Implementation

[0014] Explanation of the adhesive tearing logic (corresponding) Figure 2 Figure F) Referring to Figures F(a) to (d): After applying adhesive in S2, the entire surface of the self-adhesive seals all mesh openings (a); in S4, UV ink is sprayed in reverse order, with only the self-adhesive in the inkjet area being penetrated and anchored by the UV ink (b); in S5, when the base film is peeled off, the self-adhesive in the non-inkjet area detaches with the base film, and the mesh openings form an ink-permeable area, while the self-adhesive in the inkjet area remains between the warp and weft threads of the mesh due to UV ink anchoring, forming a screen-sealing area (c); in S6, after cleaning the residual adhesive with acetone / toluene / xylene, the screen-sealing area is clean, and the mesh openings in the image area are connected, resulting in the finished product (d). This achieves the reverse plate-making logic of "inkjet = screen sealing, no inkjet = ink permeable".

[0015] Example 1 (Comparative Example: Unoptimized) Aluminum frame, 300×400 mm, stretched with 120-mesh nylon mesh. 60 μm ordinary single-sided PET self-adhesive (surface energy approximately 38 dyne) is applied to the printing surface. The mesh is then adhered to the adhesive layer, and air is released under light pressure with a rubber roller at room temperature. The CDR file is mirrored horizontally and vertically for a reversed image output. A UV flatbed printer (Ricoh G5 printhead) directly prints white and black ink graphics, with a single curing energy of approximately 600 mJ / cm² and an ink thickness of approximately 8 μm. The adhesive is peeled off at approximately 60° for a relatively quick removal. Both sides of the mesh are wiped three times with toluene, then wiped once with acetone, and allowed to dry.

[0016] Results: The ink-adhesive peel force was only about 1.2 N / 25 mm (the ink came off easily when scratched with a fingernail), the retention rate of the sealing area after peeling off the adhesive was about 62%, the fine lines showed obvious chipping and jagged edges, and the anchoring was not firm. This comparative example is used to highlight the gains of the optimization scheme described below. Example 2 (Single Optimization: Surface Activation)

[0017] Except for the following modifications, the process is the same as in Example 1: the printing surface is corona treated before the self-adhesive is applied, and the surface energy is increased from 38 to about 51 mN / m; the other printing, adhesive removal, and cleaning conditions remain unchanged.

[0018] Results: The ink-adhesive peel force was improved to about 3.8 N / 25 mm, and the retention rate of the sealing area was about 81%, confirming that surface activation alone can significantly improve the adhesion of ink to adhesive, but the adhesive-screen interlocking problem has not yet been solved. Example 3 (Complete Anchoring Enhancement Scheme)

[0019] Aluminum frame, 300×400 mm, stretched with 120-mesh nylon mesh. Printed surface is covered with high initial tack (initial tack ≥12 N / 25mm) single-sided PET self-adhesive, adhesive thickness approximately 60 μm.

[0020] S1 Mesh Embedding: Use a 70℃ rubber roller to hot roll the cross directions so that the rubber layer is embedded into the mesh by about 1 / 2 mesh thickness; S2 Surface Activation: Before applying the adhesive, corona treatment is performed on the printing surface of the self-adhesive (power approximately 6 kW) until the surface energy is approximately 52 mN / m, with a printing interval of <30 min; S3 Multi-Layer Printing: Uses rigid polyurethane acrylate UV ink with approximately 3% silane adhesion promoter; first, pre-cures the base ink to approximately 8 μm with approximately 350 mJ / cm², then finally cureses the main ink with approximately 900 mJ / cm², for a total ink thickness of approximately 20 μm; the reverse image edge is compensated with approximately 0.15 mm mesh size to press the image to the intersection of warp and weft. S4 Low-stress adhesive tearing: Before tearing, sweep the adhesive surface with hot air at about 45°C, and tear it off at a tearing angle of about 25° and a speed of about 80 mm / s, from the non-image area to the image area at a uniform speed. S5 Interface Protection Cleaning: First wipe twice with isopropyl alcohol, then wipe with acetone and let it dry immediately.

[0021] The results of the PVC board printing test showed that the ink-adhesive peel force reached approximately 5.6 N / 25mm (no ink layer fell off after peeling test with 3M 610 tape), the retention rate of the screen sealing area after peeling off the adhesive was approximately 98.5%, the minimum retained line width was approximately 0.2 mm, the image and text were clear and free of burrs, and the anchoring firmness met the requirements of mass production ink scraping.

[0022] The above results show that the steps S1–S5 are not simply superimposed, but rather produce synergistic gains—a single measure can increase the retention rate to about 81% at most, while the combined five steps reach about 98.5%, far exceeding the sum of the individual measures, which confirms the integrity of the "ink-glue-mesh ternary anchoring structure".

[0023] Example 4 (Equivalent Substitution) Plasma treatment was used instead of corona treatment to activate the self-adhesive printing surface, with the rest being the same as in Example 3. The resulting ink-adhesive peel force was approximately 5.3 N / 25 mm, and the retention rate of the sealing area was approximately 97%, showing comparable results. This indicates that the surface activation method is not limited to corona treatment, supporting a broader scope of the claims. A variation using a wooden frame stretched with a 200-mesh nylon mesh and cleaned primarily with xylene is also within the scope of this invention. Summary of parameter ranges

[0024] Self-adhesive thickness 50–80 μm (total range 30–100) Ensure mesh embedding and enclosure Hot rolling temperature 60–80℃ Glue softening embedded mesh Adhesive embedding depth 1 / 3–1 / 2 mesh thickness Glue-mesh mechanical interlock Surface energy ≥48 mN / m (preferably 50–56) Ink-adhesive chemical anchoring curing energy Pre-curing: 300–400 mJ / cm² / Final curing: 800–1200 mJ / cm² Segmented curing Total ink thickness 15–22 μm (preferably 18–22 μm) Multi-layer structure Tearing angle ≤30° (preferably 20–30°) Reduce tear stress Adhesive peeling speed 50–100 mm / s (preferably 60–90 mm / s) Tear off at a constant speed Peeling force ≥5.0 N / 25mm Anchoring qualification line Retention rate of the closed area ≥95% (preferably ≥98%) Finished Product Specifications Safety Instructions

[0025] Acetone, toluene, and xylene are restricted organic solvents, and are described as "optional cleaning agents" in the instructions. In actual operation, ventilation and personal protective equipment should be used in conjunction with them. In scenarios with high environmental protection requirements, ethanol / isopropanol downgrade cleaning solutions can be used to replace some of the strong solvents.

Claims

1. A method for manufacturing a UV inkjet screen printing stencil, characterized in that, The process includes the following steps: A screen frame made of aluminum or wood is used; a nylon mesh is stretched and fixed onto the frame to create a blank screen printing plate with open mesh openings; a layer of single-sided self-adhesive film is applied to the printing surface of the blank screen printing plate, with the adhesive side facing the nylon mesh; the pattern to be printed is mirrored to obtain a reverse screen printing image, which is then fed into a UV flatbed printer; the blank screen printing plate with the self-adhesive film is placed on the UV flatbed printer's worktable, and UV ink is sprayed onto the reverse image and cured, forming a reverse image anchoring layer on the self-adhesive surface; the self-adhesive substrate is peeled off from the mesh side, allowing the self-adhesive in the un-inked areas to detach with the substrate, opening the mesh openings, while the self-adhesive in the ink-sprayed areas is anchored to the mesh by the UV ink to form a sealing layer; the screen is cleaned using one or more mixed solvents selected from acetone, toluene, and xylene to remove residual adhesive residue and ink flakes, thus obtaining the screen printing plate.

2. A UV inkjet screen printing stencil prepared by the method of claim 1, characterized in that, include: A wire mesh frame made of aluminum or wood, and a nylon mesh fabric stretched and fixed to the wire mesh frame; The nylon mesh fabric has interconnected mesh openings, which are divided into ink-permeable areas and sealing areas. The sealing area consists of an adhesive layer retained between the warp and weft threads of the mesh fabric. This adhesive layer remains after being anchored by UV inkjet printing and peeled off with the base film. The ink-permeable area is an open area with interconnected mesh openings. The surface of the sealing area is cleaned with one or more mixed solvents selected from acetone, toluene, and xylene to remove residual adhesive. The distribution pattern of the sealing area corresponds to the mirror image of the pattern to be printed, so that the ink-permeable area appears as a positive image when viewed from the squeegee surface.

3. The method according to claim 1, characterized in that: The mesh frame is made of aluminum alloy profile or solid wood / multi-layer wood board; the nylon mesh has a mesh count of 80–300 and is bonded and stretched to the mesh frame with polyurethane or acrylate adhesive.

4. The method according to claim 1, characterized in that: The thickness of the single-sided self-adhesive film is 30–100 μm. Before application, the nylon mesh is degreased and dust-removed. After application, it is rolled to remove air bubbles so that the adhesive layer adheres to the mesh without air bubbles.

5. The method according to claim 1, characterized in that: The mirror reversal process involves simultaneously mirroring the pattern to be printed along both the horizontal and vertical axes; the UV ink curing energy during inkjet printing is 300–1200 mJ / cm².

6. The method according to claim 1, characterized in that: When the self-adhesive substrate is peeled off, the self-adhesive in the inkjet area remains between the warp and weft threads of the mesh due to the UV ink penetration and anchoring, forming a non-ink-permeable closed area. The mesh holes in the non-inkjet area are restored to open, forming an ink-permeable printing area.

7. The method according to claim 1, characterized in that: In the cleaning step, acetone, toluene, and xylene are used alone or in any proportion, and 5-20% ethanol or ethyl acetate can be added as a co-solvent. After wiping with non-woven fabric on both sides 1-5 times, the mixture is allowed to evaporate and dry naturally.

8. The UV inkjet screen printing stencil according to claim 2, characterized in that: The self-adhesive layer in the sealing area fills the gaps between the interwoven warp and weft threads of the mesh fabric, with a thickness of 30–100 μm; the mesh in the ink-permeable area is open and the inner wall is free of adhesive residue.

9. The UV inkjet screen printing stencil according to claim 2, characterized in that: The mesh frame is made of aluminum alloy or wood, the nylon mesh has a mesh count of 80–300, and the minimum line width of the sealing area is 0.2–2.0 mm.

10. The UV inkjet screen printing stencil according to claim 2, characterized in that: The screen is prepared by the method described in any one of claims 1 to 7, and the boundary between the sealing area and the ink penetration area is defined by the UV inkjet curing line.

11. An anchoring enhancement method in the production of UV inkjet screen printing stencils, characterized in that, The process includes the following steps: S1, applying the self-adhesive film to the nylon mesh using hot rolling at 60–80℃, embedding the adhesive layer into the mesh openings by 1 / 3–1 / 2 of the mesh thickness, forming a mechanical interlock between the adhesive and the mesh; S2, subjecting the self-adhesive printing surface to corona or plasma treatment until the surface energy is ≥48 mN / m, or pre-coating a 1–2 μm thick UV adhesion promoter layer to form a chemical anchoring interface between the ink and the adhesive; S3, using rigid polyurethane acrylate UV inkjet printing, adding 2–5% silane adhesion promoter to the ink, first pre-curing the base ink to 6–10 μm with an energy of 300–400 mJ / cm², then finally curing the main ink to a total thickness of 15–22 μm with an energy of 800–1200 mJ / cm² for a double-layer structure printing; S4, before peeling off the adhesive, sweeping the adhesive surface with hot air at 40–50℃, then peeling at a ≤30° angle and 50–100°... mm / s speed, tearing from non-image area to image area; S5, when cleaning, first wipe with ethanol or isopropanol 1-2 times, then wipe with acetone, wipe and dry immediately, protect the ink-adhesive-mesh ternary anchoring structure.

12. The method according to claim 11, characterized in that: The self-adhesive described in S1 is a high initial tack type, with an initial tack force ≥12 N / 25 mm, an adhesive layer thickness of 50–80 μm, and hot rolling is performed in a cross direction.

13. The method according to claim 11, characterized in that: The corona treatment power in S2 is 4–10 kW, the surface energy after treatment reaches 50–56 mN / m, and the printing interval is controlled within 30 min.

14. The method according to claim 11, characterized in that: The edges of the reverse image described in S3 are compensated with 0.1–0.2 mm mesh size so that the inkjet area covers the warp and weft intersections of the nylon mesh.

15. The method according to claim 11, characterized in that: In S3, the total ink layer thickness of the double-layer inkjet printing is controlled at 18–22 μm, and the base ink and the main ink are hard UV inks of the same color.

16. The method according to claim 11, characterized in that: The S4 tear angle is controlled at 20–30°, and the tearing speed is 60–90 mm / s.

17. The method according to claim 11, characterized in that: The cleaning described in S5 involves dabbing the nonwoven fabric with solvent and immediately blotting it dry, with the solvent remaining on the fabric surface for no more than 10 seconds.

18. The method according to claim 11, characterized in that: After S1–S5 treatment, the peel force between UV ink and self-adhesive is ≥5.0 N / 25mm, and the retention rate of the sealing area after peeling off the adhesive is ≥95%.

19. The use of the anchoring enhancement method according to any one of claims 11 to 18 in screen printing plate making, characterized in that: Used to anchor the adhesive in the inkjet area to the screen fabric by UV flatbed printing on a blank screen printing plate with self-adhesive labels, forming a sealing layer.

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