Methods to extend the lifespan of screen printing stencils

Abstract

This invention provides a method for improving the lifespan of screen printing stencils. A filling and repair area is formed in the overlapping region of the steel wire mesh and the polyester wire mesh through thermal fusion bonding. During the UV emulsification process in this filling and repair area, a grid-type film with alternating black and white areas is first used to cover the UV emulsion before the first exposure. The polymerization stress caused by the curing shrinkage of the UV emulsion covered in the white areas can be released through the uncured areas of the UV emulsion covered in the black areas. This disperses the shrinkage stress generated during UV emulsion curing, preventing its concentration and ensuring uniform and rapid release. Then, the black and white film is removed, and the UV emulsion is exposed a second time using ultraviolet light after the first exposure, allowing the UV emulsion to fully cure. This reduces or eliminates the shrinkage stress generated during UV emulsion curing, extending the lifespan of the screen printing stencil.

Description

Technical Field

[0001] This invention belongs to the technical field of solar cell processing and manufacturing equipment, and in particular, relates to a method for improving the lifespan of screen printing stencils. Background Technology

[0002] Screen printing is a process used in the mass production of solar cells. Its purpose is to imprint a conductive paste containing metal onto a silicon wafer through the mesh of a screen to form circuits and / or electrodes. Currently, screen printing stencils for solar cell electrodes typically use metal wire mesh as the printing area, with a polyester mesh composite around the perimeter to give the stencil some resilience for printing. Conventional stencil making uses UV emulsion to fill and repair the overlapping areas of the wire mesh and polyester mesh composite. However, due to the significant shrinkage stress generated during the UV emulsion curing process, the wires of the metal wire mesh are prone to breakage when the squeegee presses against the screen printing stencil, leading to screen breakage and reducing the stencil's lifespan. Summary of the Invention

[0003] The purpose of this invention is to provide a method for improving the lifespan of screen printing stencils. During the UV emulsion curing process, the UV emulsion is subjected to regional and secondary exposure to avoid concentrated shrinkage stress generated during UV emulsion curing and to effectively release the shrinkage stress generated during the UV emulsion curing process, thereby extending the lifespan of the screen printing stencil.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for improving the lifespan of screen printing stencils, comprising the following steps:

[0005] Hot melt lamination: The hot melt adhesive film is hot melted using a hot pressing process. The polyester wire mesh and the steel wire mesh are hot melt laminated through the hot melt adhesive film. The periphery of the steel wire mesh and the overlapping area of ​​the hot melt laminated polyester wire mesh form a filling and repair area.

[0006] UV emulsion coating and filling treatment: UV emulsion is applied to fill the repair area and the applied UV emulsion is dried.

[0007] Exposure and curing process: Cover the filling and repair area coated with the UV emulsion with a black and white striped film, perform a first exposure with ultraviolet light, then remove the black and white striped film, and perform a second exposure with ultraviolet light, so that the UV emulsion filling the filling and repair area is photocured through two exposures, and a screen printing stencil with a double-exposure cured UV emulsion is obtained.

[0008] Optionally, in the exposure curing process, the black and white film is a grid-type film in which the black and white areas are distributed in a grid pattern.

[0009] Optionally, the mesh film has multiple black area meshes and multiple white area meshes formed on it, wherein the black area meshes and the white area meshes have the same shape and size.

[0010] Optionally, the length of the black area grid is less than or equal to 2mm, and the width of the black area grid is less than or equal to 2mm; or, the length of the white area grid is less than or equal to 2mm, and the width of the white area grid is less than or equal to 2mm.

[0011] Optionally, the diameter of the black area grid is less than or equal to 2 mm, and the diameter of the white area grid is less than or equal to 2 mm; or, the area of ​​the black area grid is less than or equal to 4 mm². 2 The area of ​​the white grid region is less than or equal to 4 mm². 2 .

[0012] Optionally, in each horizontal row of the grid-type film, each white area grid is located between two adjacent black area grids; in each vertical row of the grid-type film, each white area grid is located between two adjacent black area grids.

[0013] Optionally, in the exposure curing process, the exposure time for the first exposure is 50 to 120 seconds.

[0014] Optionally, in the exposure curing process, the hot melt bonding process involves a hot melt bonding temperature of 180–200°C and a hot melt bonding time of 25–30 minutes.

[0015] Optionally, in the hot melt lamination process, the hot melt adhesive film is a polyurethane film or a PET film.

[0016] Optionally, the exposure time of the second exposure shall not exceed 70% of the sum of the exposure time of the first exposure and the exposure time of the second exposure.

[0017] Compared with the prior art, one or more technical solutions in the embodiments of the present invention have at least one of the following beneficial effects:

[0018] The method for improving the lifespan of screen printing stencils in this invention involves forming a filling and repair area in the overlapping region of the steel wire mesh and the polyester wire mesh through thermal fusion lamination. UV emulsion is applied and filled into this filling and repair area. During the UV emulsification process in this area, a grid-type film with alternating black and white areas is first used to cover the UV emulsion before a first exposure. The polymerization stress caused by the curing shrinkage of the UV emulsion covered by the white areas of the black and white film can be released through the uncured areas of the UV emulsion covered by the black areas of the black and white film. This disperses the shrinkage stress generated during UV emulsion curing, preventing the stress from becoming concentrated and allowing for uniform and rapid release of shrinkage stress during UV emulsion curing. Then, only the black and white film needs to be removed, and a second exposure is performed using ultraviolet light on the UV emulsion that was previously exposed in sections through the black and white film. This ensures complete curing of the UV emulsion, reducing or even eliminating the shrinkage stress caused by UV emulsion curing, thereby extending the lifespan of the screen printing stencil. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a screen printing stencil provided in an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of the black and white striped film in an embodiment of the present invention.

[0022] The following are the labeling elements in the figure:

[0023] 1-Steel wire mesh; 2-Polyester wire mesh; 3-Filling and repair area;

[0024] 4-Black and white striped film; 41-White area; 42-Black area. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] This invention provides a method for improving the lifespan of screen printing stencils, comprising the following steps:

[0027] Step S01, hot melt lamination treatment: The hot melt adhesive film is hot melted using a hot pressing process. The polyester wire mesh and steel wire mesh are hot melt laminated through the hot melt adhesive film. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by hot melt lamination creates a filling and repair area.

[0028] Step S02, UV emulsion coating and filling treatment: UV emulsion is coated and filled into the repair area 3, and the coated UV emulsion is dried.

[0029] Step S03, Exposure and Curing Process: Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4, perform the first exposure with ultraviolet light, then remove the black and white striped film 4, and perform the second exposure with ultraviolet light, so that the UV emulsion filling the filling and repair area 3 is cured by light through two exposures, and obtain a screen printing stencil with UV emulsion cured by two exposures.

[0030] The preparation method of the present invention will be explained in further detail below.

[0031] In the exposure curing process, the first exposure time is 50–120 seconds, and the second exposure time does not exceed 70% of the sum of the first and second exposure times. In the hot-melt lamination process, the temperature is 180–200°C, and the lamination time is 25–30 minutes, thereby hot-melting the outer edge of the steel wire mesh 14 and the inner edge of the polyester wire mesh 22 together. Specifically, in the hot-melt lamination process, the hot-melt adhesive film is a polyurethane film or a PET film.

[0032] In the exposure and curing process, the black and white alternating film 4 is a grid-type film with white areas 41 and black areas 42 arranged in a grid pattern. When the black and white alternating film 4, with alternating black areas 42 and white areas 41, is covered with UV emulsion and exposed, the white areas 41 of the black and white alternating film 4 allow UV light to pass through, causing the UV emulsion covered by the white areas 41 to undergo a curing reaction. Simultaneously, the black areas 42 of the black and white alternating film 4 do not allow UV light to pass through, causing the UV emulsion covered by the black areas 42 of the black and white alternating film 4 to not undergo a curing reaction. Since the UV emulsion transforms from a non-polymerized state to a highly polymerized state, the polymerization stress caused by the curing shrinkage of the UV emulsion covered by the white areas 41 of the black and white alternating film 4 can be released through the uncured areas covered by the black areas 42 of the black and white alternating film 4. This avoids the concentration of shrinkage stress generated during UV emulsion curing and effectively releases the shrinkage stress generated during the UV emulsion curing process, thus extending the service life of the screen printing stencil.

[0033] Specifically, the grid-type film has multiple black areas 42 and multiple white areas 41 formed on it. The black areas 42 and the white areas 41 have the same shape and size. Among them, the white areas 41 correspond to the white areas 41 of the black and white alternating film 4 mentioned above, and the black areas 42 correspond to the white areas 41 of the black and white alternating film 4 mentioned above. Because multiple black areas 42 and multiple white areas 41 are spaced apart and evenly distributed on the grid-type film, and each black area 42 and each white area 41 has the same shape and size, during the exposure process of exposing the alternating black and white film 4 to UV emulsion, the polymerization stress caused by the curing shrinkage of the UV emulsion covered by the white areas 41 of the alternating black and white film 4 can be released more evenly through the uncured areas covered by the black areas 42 of the alternating black and white film 4. This further disperses the shrinkage stress generated by the curing of the UV emulsion, allowing the shrinkage stress generated during the curing process of the UV emulsion to be released more evenly and quickly, thereby extending the service life of the screen printing stencil.

[0034] In some embodiments, the black area 42 grid is a rectangular grid with a length and width less than or equal to 2 mm. The white area 41 grid is also a rectangular grid with a length and width less than or equal to 2 mm. Since the UV emulsion transitions from a non-polymerized state to a highly polymerized state, excessively large areas of UV emulsion curing and polymerization will result in relatively significant curing shrinkage, which introduces polymerization stress. Conversely, curing and polymerization of small areas of UV emulsion can relatively reduce or even eliminate the polymerization stress caused by curing shrinkage. Specifically, when both the black area 42 grid and the white area 41 grid are square grids, and their dimensions are greater than 2 mm × 2 mm, the UV emulsion curing and polymerization will result in relatively significant curing shrinkage. The excessive polymerization stress generated by this shrinkage is detrimental to reducing or eliminating the polymerization stress caused by curing shrinkage. Furthermore, since the black area 42 grids and white area 41 grids with a size greater than 2mm×2mm are evenly distributed on the grid-type film, and each black area 42 grid has the same shape and size as each white area 41 grid, during the exposure process of exposing the UV emulsion to the alternating black and white film 4 with alternating black areas 42 and white areas 41, the polymerization stress caused by the curing shrinkage of the UV emulsion covered by the white area 41 of the alternating black and white film 4 can be evenly released through the uncured area covered by the black area 42 of the alternating black and white film 4. This further disperses the shrinkage stress generated by the curing of the UV emulsion, avoids the concentration of shrinkage stress generated by the curing of the UV emulsion, and allows the shrinkage stress generated during the curing process of the UV emulsion to be released more evenly and quickly, thereby extending the service life of the screen printing stencil.

[0035] In other embodiments, when both the black area 42 and the white area 41 are circular grids, the diameter of the black area 42 grid is less than or equal to 2 mm, and the diameter of the white area 41 grid is less than or equal to 2 mm. Of course, the black area 42 grid and the white area 41 grid can also be elliptical, rhomboid, pentagonal, or other shapes; in this case, the area of ​​the black area 42 grid is less than or equal to 4 mm². 2 Furthermore, the area of ​​the white area 41 grid is less than or equal to 4 mm². 2During the exposure process of UV emulsion covered by the alternating black and white film 4 with black areas 42 and white areas 41, the polymerization stress caused by the curing shrinkage of the UV emulsion covered by the white area 41 of the alternating black and white film 4 can also be released through the uncured area covered by the black area 42 of the alternating black and white film 4. This further disperses the shrinkage stress generated by the curing of the UV emulsion, avoids the concentration of shrinkage stress generated by the curing of the UV emulsion, and allows the shrinkage stress generated during the curing process of the UV emulsion to be released more evenly and quickly, thereby extending the service life of the screen printing stencil.

[0036] In some embodiments, in each horizontal row of the grid-type film, each white area 41 grid is located between two adjacent black areas 42 grids; in each vertical row of the grid-type film, each white area 41 grid is located between two adjacent black areas 42 grids. With this grid arrangement, when the grid-type film, with alternating black areas 42 and white areas 41, is covered with UV emulsion for exposure, the polymerization stress caused by the curing shrinkage of the UV emulsion covered by the white areas 41 of the grid-type film can be fully and evenly released through the uncured areas covered by the black areas 42 of the black and white alternating film 4. This further disperses the shrinkage stress generated by UV emulsion curing, preventing the concentration of shrinkage stress during UV emulsion curing, and effectively releasing the shrinkage stress generated during UV emulsion curing, thus extending the service life of the screen printing stencil.

[0037] The method for improving the lifespan of screen printing stencils provided by this invention involves forming a filling and repair area 3 in the overlapping area where the steel wire mesh 1 and the polyester wire mesh 2 are thermally melt-laminated. UV emulsion is applied and filled into this filling and repair area 3. During the UV emulsification process in the filling and repair area 3, a grid-type film with alternating black areas 42 and white areas 41 is used to cover the UV emulsion before the first exposure. The polymerization stress caused by the curing shrinkage of the UV emulsion covered by the white areas 41 of the black and white film 4 can be released through the uncured areas of the UV emulsion covered by the black areas 42 of the black and white film 4. This disperses the shrinkage stress generated during UV emulsion curing, preventing the stress from concentrating and allowing for uniform and rapid release of the shrinkage stress generated during UV emulsion curing. Then, only the black and white film 4 needs to be removed, and the UV emulsion exposed in sections through the black and white film 4 is exposed a second time using ultraviolet light, allowing the UV emulsion to fully cure. This reduces or even eliminates the shrinkage stress caused by UV emulsion curing, thereby extending the lifespan of the screen printing stencil.

[0038] To more effectively illustrate the technical solution of the present invention, the technical solution of the present invention will be described below through specific embodiments.

[0039] Example 1

[0040] 1) The hot melt adhesive film is hot melted using a hot pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot melted together using the hot melt adhesive film. The hot melt bonding temperature is 190℃ and the hot melt bonding time is 28 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot melt bonding forms a filling and repair area 3.

[0041] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0042] 3) Cover the filling and repair area 3 coated with UV emulsion using a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 2.5mm×2.5mm square grids. Perform the first exposure with ultraviolet light for 100 seconds. Then remove the black and white striped film 4 and perform the second exposure with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil for the UV emulsion cured by two exposures.

[0043] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 15.5N.

[0044] Example 2

[0045] 1) The hot melt adhesive film is hot melted using a hot pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot melted together using the hot melt adhesive film. The hot melt bonding temperature is 180℃ and the hot melt bonding time is 25 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot melt bonding forms a filling and repair area 3.

[0046] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0047] 3) Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 2.0mm×2.0mm square grids. The first exposure is performed with ultraviolet light for 100 seconds. Then the black and white striped film 4 is removed, and the second exposure is performed with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil for the UV emulsion cured by two exposures.

[0048] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 14.5N.

[0049] Example 3

[0050] 1) The hot-melt adhesive film is hot-melted using a hot-pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot-melted and bonded together using the hot-melt adhesive film. The hot-melt bonding temperature is 200℃ and the hot-melt bonding time is 30 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot-melt bonding forms a filling and repair area 3.

[0051] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0052] 3) Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 1.5mm×1.5mm square grids. Perform the first exposure with ultraviolet light for 100 seconds. Then remove the black and white striped film 4 and perform the second exposure with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil for curing UV emulsion through two exposures.

[0053] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 14.3N.

[0054] Example 4

[0055] 1) The hot-melt adhesive film is hot-melted using a hot-pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot-melted and bonded together using the hot-melt adhesive film. The hot-melt bonding temperature is 190℃ and the hot-melt bonding time is 30 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot-melt bonding forms a filling and repair area 3.

[0056] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0057] 3) Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 1mm×1mm square grids. The first exposure is performed with ultraviolet light for 100 seconds. Then the black and white striped film 4 is removed, and the second exposure is performed with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil with UV emulsion cured by two exposures.

[0058] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 14.2N.

[0059] Example 5

[0060] 1) The hot-melt adhesive film is hot-melted using a hot-pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot-melted and bonded together using the hot-melt adhesive film. The hot-melt bonding temperature is 190℃ and the hot-melt bonding time is 30 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot-melt bonding forms a filling and repair area 3.

[0061] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0062] 3) Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 0.8mm×0.8mm square grids. Perform the first exposure with ultraviolet light for 100 seconds. Then remove the black and white striped film 4 and perform the second exposure with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil for curing UV emulsion through two exposures.

[0063] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 14.0N.

[0064] Example 6

[0065] 1) The hot-melt adhesive film is hot-melted using a hot-pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot-melted and bonded together using the hot-melt adhesive film. The hot-melt bonding temperature is 190℃ and the hot-melt bonding time is 30 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot-melt bonding forms a filling and repair area 3.

[0066] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0067] 3) Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 0.5mm×0.5mm square grids. Perform the first exposure with ultraviolet light for 100 seconds. Then remove the black and white striped film 4 and perform the second exposure with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil with UV emulsion cured by two exposures.

[0068] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 13.7N.

[0069] Example 7

[0070] 1) The hot-melt adhesive film is hot-melted using a hot-pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot-melted and bonded together using the hot-melt adhesive film. The hot-melt bonding temperature is 190℃ and the hot-melt bonding time is 30 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot-melt bonding forms a filling and repair area 3.

[0071] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0072] 3) Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 0.5mm×0.5mm square grids. Perform the first exposure with ultraviolet light for 100 seconds. Then remove the black and white striped film 4 and perform the second exposure with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil with UV emulsion cured by two exposures.

[0073] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 13.5N.

[0074] Example 8

[0075] 1) The hot-melt adhesive film is hot-melted using a hot-pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot-melted and bonded together using the hot-melt adhesive film. The hot-melt bonding temperature is 190℃ and the hot-melt bonding time is 30 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot-melt bonding forms a filling and repair area 3.

[0076] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0077] 3) Cover the filling and repair area 3 coated with UV emulsion with a black and white striped film 4. Multiple black area grids 42 and multiple white area grids 41 are formed on the black and white striped film 4. The black area grids 42 and the white area grids 41 have the same shape and size, which are all 0.5mm×0.5mm square grids. The first exposure is performed with ultraviolet light for 120 seconds. Then the black and white striped film 4 is removed, and the second exposure is performed with ultraviolet light for 100 seconds. This allows the UV emulsion filling the filling and repair area 3 to be cured by light through two exposures, thus obtaining a screen printing stencil for curing UV emulsion through two exposures.

[0078] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 13.2N.

[0079] Comparative Example 1

[0080] 1) The hot-melt adhesive film is hot-melted using a hot-pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot-melted and bonded together using the hot-melt adhesive film. The hot-melt bonding temperature is 190℃ and the hot-melt bonding time is 30 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot-melt bonding forms a filling and repair area 3.

[0081] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0082] 3) Cover the UV emulsion-coated filling and repair area 3 with white film, and cover the area other than the UV emulsion-coated filling and repair area 3 with black film. Expose the UV emulsion-coated filling and repair area 3 to ultraviolet light for 200 seconds to allow the UV emulsion filling the filling and repair area 3 to be cured by light, thus obtaining a screen printing stencil with UV emulsion cured by one exposure.

[0083] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 15.5N.

[0084] Comparative Example 2

[0085] 1) The hot melt adhesive film is hot melted using a hot pressing process. The polyester wire mesh 2 and the steel wire mesh 1 are hot melted together using the hot melt adhesive film. The hot melt bonding temperature is 190℃ and the hot melt bonding time is 28 minutes. The overlapping area of ​​the steel wire mesh 1 and the polyester wire mesh 2 formed by the hot melt bonding forms a filling and repair area 3.

[0086] 2) Apply UV emulsion to the repair area 3 and dry the entire screen printing plate in an oven at 40°C for 20 minutes to dry the applied UV emulsion.

[0087] 3) Cover the UV emulsion-coated filling and repair area 3 with white film, and cover the area other than the UV emulsion-coated filling and repair area 3 with black film. Expose the UV emulsion-coated filling and repair area 3 to ultraviolet light for 220 seconds to allow the UV emulsion filling the filling and repair area 3 to be cured by light, thus obtaining a screen printing stencil with UV emulsion cured by one exposure.

[0088] 4) The cured UV emulsion was subjected to a second heat treatment, and the tension of the UV emulsion area was measured to be 15.8N.

[0089] The relevant performance test results of Examples 1 to 8 and Comparative Examples 1 to 2 are listed in Table 1 below.

[0090] Table 1. Test results of UV emulsion regional tension tests in Examples 1 to 8 and Comparative Examples 1 to 2.

[0091]

[0092] As can be seen from the analysis in Table 1 above, compared with Comparative Examples 1 and 2, Examples 1 to 8 involve first exposing the UV emulsion to a grid-like film with alternating black and white areas 42 and 41, then removing the black and white film 4, and finally exposing the UV emulsion to UV light in a second exposure. This two-stage, area-by-area exposure allows the UV emulsion to fully cure, significantly reducing the tension in the UV emulsion area. This indicates that the two-stage, area-by-area exposure effectively reduces the shrinkage stress generated during UV emulsion curing, thereby extending the lifespan of the screen printing stencil. Furthermore, Examples 1 to 8 show that because the UV emulsion's photocuring process transforms it from a non-polymerized state to a highly polymerized state, the curing and polymerization of a small area of ​​UV emulsion can relatively reduce or even eliminate the polymerization stress caused by curing shrinkage, resulting in a significant decrease in the tension in the UV emulsion area. It is worth noting that when the black area 42 grid and the white area 41 grid on the black and white alternating film 4 have a size greater than 2mm×2mm, the tension of the UV emulsion area is almost the same as that of the UV emulsion cured by a single exposure in Comparative Example 1. This is because the curing and polymerization of a large area of ​​UV emulsion will produce relatively obvious curing shrinkage. The shrinkage will bring polymerization stress, which will cause the tension of the UV emulsion area to increase significantly, resulting in the tension of the UV emulsion area not decreasing significantly.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the lifespan of a screen printing stencil, characterized in that, Includes the following steps: Hot melt lamination: The hot melt adhesive film is hot melted using a hot pressing process. The polyester wire mesh and the steel wire mesh are hot melt laminated through the hot melt adhesive film. The periphery of the steel wire mesh and the overlapping area of ​​the hot melt laminated polyester wire mesh form a filling and repair area. UV emulsion coating and filling treatment: UV emulsion is applied to fill the repair area and the applied UV emulsion is dried. Exposure and curing process: Cover the filling and repair area coated with the UV emulsion with a black and white striped film, perform a first exposure with ultraviolet light, then remove the black and white striped film, and perform a second exposure with ultraviolet light, so that the UV emulsion filling the filling and repair area is photocured through two exposures, and a screen printing stencil with a double-exposure cured UV emulsion is obtained.

2. The method for improving the lifespan of a screen printing stencil as described in claim 1, characterized in that, In the exposure and curing process, the black and white film is a grid-type film in which the black and white areas are distributed in a grid pattern.

3. The method for improving the lifespan of a screen printing stencil as described in claim 2, characterized in that, The mesh film has multiple black area meshes and multiple white area meshes formed on it, and the black area meshes and the white area meshes have the same shape and size.

4. The method for improving the lifespan of a screen printing stencil as described in claim 3, characterized in that, The length of the black area grid is less than or equal to 2mm, and the width of the black area grid is less than or equal to 2mm; or, the length of the white area grid is less than or equal to 2mm, and the width of the white area grid is less than or equal to 2mm.

5. The method for improving the lifespan of a screen printing stencil as described in claim 3, characterized in that, The diameter of the black area grid is less than or equal to 2 mm, and the diameter of the white area grid is less than or equal to 2 mm; or, the area of ​​the black area grid is less than or equal to 4 mm². 2 The area of ​​the white grid region is less than or equal to 4 mm². 2 .

6. The method for improving the lifespan of a screen printing stencil as described in claim 3, characterized in that, In each horizontal row of the grid-type film, each white area grid is located between two adjacent black area grids; in each vertical row of the grid-type film, each white area grid is located between two adjacent black area grids.

7. The method for improving the lifespan of a screen printing stencil as described in claim 1, characterized in that, In the exposure curing process, the exposure time for the first exposure is 50 to 120 seconds.

8. The method for improving the lifespan of a screen printing stencil as described in claim 1, characterized in that, In the hot melt composite process, the temperature for hot melt composite is 180–200°C, and the hot melt composite time is 25–30 minutes.

9. The method for improving the lifespan of a screen printing stencil as described in claim 1, characterized in that, In the hot melt lamination process, the hot melt adhesive film is a polyurethane film or a PET film.

10. The method for improving the lifespan of a screen printing stencil as described in any one of claims 1 to 9, characterized in that, The exposure time of the second exposure shall not exceed 70% of the sum of the exposure time of the first exposure and the exposure time of the second exposure.

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