Screen printing has many advantages, such as: thick ink layer and strong coverage, not limited by the size and shape of the substrate, soft layout and small printing pressure, suitable for various types of ink and light fastness, etc. More and more widely used in electronics industry, ceramic decal industry and textile printing and dyeing industry and other fields. With the continuous progress of society, people have higher and higher requirements for the quality of screen printing. How to improve the quality of screen printing is a problem that people in the industry are very concerned about. The quality of screen printing directly affects the quality of screen printing.
This paper mainly discusses the plate making work of screen printing.
The plate-making process of screen printing is: drawing the screen → washing the screen → printing the plate.
details as follows:
1. Pull the net
1. Process flow
①According to the net drawing plan of the team leader of the version room on that day, find out the corresponding specifications of the screen frame and the corresponding mesh yarn.
②Put the screen frame flat on the workbench and check whether it is parallel.
③Choose the undeformed screen frame and apply the glue evenly on the textured side of the screen frame with an oil brush. After air-drying for 10mm, apply the second time and let it dry naturally for more than 12 hours.
④Put the mesh frame coated with mesh glue on the lifting platform with the mesh glue side facing up.
⑤ Take out the mesh yarn of the corresponding mesh and specification (wide mesh yarn for mechanical large mesh machine, narrow mesh yarn for cylinder type small mesh machine), spread out the mesh yarn, first clamp the end of the mesh yarn, and then Clamp the opposite side, and then clamp the other two sides in turn.
⑥Turn on the air source switch of the cylinder-type drawing machine or turn the gear of the mechanical-type drawing machine.
⑦ The tension of the maximum point of the mesh is 20N in the first pull. Use the mesh tension meter to measure the tension of each point, and loosen the mesh clip at the place with the largest tension slightly, so that the tension of the whole mesh tends to be consistent.
⑧ Rotate the gear of the mechanical drawing machine at an interval of 20 minutes to make the tension reach 24~26N, and then turn the gear at an interval of 10~20 minutes to pull the tension to 28N.
⑨Smear and stick mesh glue on the mesh with the mesh frame, air-dry for 2 to 3 hours, release the mesh machine, and cut the mesh with a blade 1cm away from the edge of the mesh frame.
①Use a whiteboard pen to fill in the mesh number of the mesh and the date of pulling the mesh on the edge of the screen frame, and then use the mesh tension to measure the tension of each mesh at nine points, fill in the corresponding screen record card, and stick it with tape. on the corresponding screen.
2. Control points
① The screen frame used for pulling the net must be flat and not deformed.
②The thickness of the glue should be uniform when brushing. It should be brushed twice, and the net can be drawn after it is naturally air-dried.
③When pulling the net, the tension should be pulled to 28N in 3 times, and the tension should reach 22N after air-drying for 72hrs.
2. Washing the net
1. Process flow
① Take the screen plate that has been air-dried for 72 hours and take it to the printing room. Seal the outer and inner edges of the screen frame with yellow transparent glue and middle leather glue.
②Tear off the transparent tape of the old silk screen soaked in the net washing tank, then wash the photosensitive pulp with stripping water, and then take it to the outside storage rack and dry it.
③ Wash off a layer of oil stains and other miscellaneous stains on the net with washing water, and place it on a drying rack to dry.
④ Take the cleaned and air-dried mesh frame to the mesh washing pool of the mesh drying room and scrub it with washing powder once, then use a high-pressure water gun to punch the mesh holes again, and then place it on a drying rack to dry.
⑤After washing the washing powder, put the screen plate collected from the production department on the same day and soak it in the pool.
2. Control points
①There should be no oil stains or cloth wool on the mesh.
②When sealing yellow tape and kraft tape, make sure that the tape is flat and firmly adhered to the screen frame and mesh.
③ When flushing the screen with a water gun, The mesh of the entire screen plate must be punched evenly, and no part is not hit.
④Each washed net should be inspected by light.
1. Process flow
①Wash the washing powder and dry the screen to the darkroom.
② Visually check whether the mesh of the screen is transparent under the light. If there is no connection or small hole, use a pencil to circle it, and avoid it when drying the screen.
③ Apply the prepared photosensitive paste on the inspected net with a scraper. When scraping the photosensitive paste, the empty screen should be placed at an angle of 45%C, and the first scraping should be done 6 times (ie: 4 times on the contact surface of the substrate and 2 times on the back). After the first scraping, put it in the oven and bake at 459C for 15 minutes, take out the screen and continue scraping for the second time (the number of methods is the same as the first). After scraping the photosensitive paste for the second time, put it in the oven and bake at 45°C for 45 minutes (note: the hand is from bottom to top when scraping the paste).
④Choose screen plates with different specifications and meshes according to production needs (Note: 140T old screen is used for varnish, 140T screen is generally used for white background with a tension of not less than 18N/CM, and 140T is used for ordinary Pantone special colors. Mesh with a tension of not less than 18N/CM, metal and fluorescent colors with a 10T tension of not less than 18N/CM.
⑤ Check the net film to be dried to see if the film is folded, scratched, stained, etc.
⑥ Use a red pen to mark the scratches on the film, and use white electric oil or alcohol to wipe the surface of the film clean.
⑦Use the screen positioning ruler for positioning, and set different positions according to the positioning line of the positioning film according to the screen of different specifications (there are three positioning standard lines for fourdrinier net, automatic, and loading and unloading machine).
⑧ Select the corresponding deformation strips for different specifications of the screen frame and place them at the prescribed standard intervals, and stick and fix them with transparent tape.
⑨ When exposing for the first time, lay the side of the film on the drying machine.
Back to set the corresponding exposure time, the first exposure is based on the size of the pattern, the exposure of the small screen drying machine is 45 ~ 100S, and the large screen drying machine is 140 ~ 300S.
①Close the cloth cover for air extraction.
②Take out the exposed screen plate, remove the film and deformed strip, soak it in a pool for 2 minutes (developing), align the pattern with a water gun, and require that the pattern on the printing surface be evenly opened.
③Put the developed wire mesh on a drying rack and blow it dry with a fan.
④ Put the wire mesh that has been exposed to the first light and air-dried into the drying machine for the second exposure (the exposure time is 3 to 5 times the exposure time of the first time).
⑤Put the sun-dried screen plate flat on the screen sealing table (the contact surface with the substrate is facing up).
⑥ Pour a little sealing paste onto the screen, and then evenly apply the sealing paste around the exposure pattern with a scraper.
⑦ Take the sealed net to the sealing frame. Check it through the light to see if the pattern is not clear, net marks, shadows, and sand holes. be re-tanned.
⑧ Mark the order number and color sequence of the sealed net on the net frame with a signature pen. Find out the stencil card that matches the stencil number and stick it on the stencil.
2. Control points
①The front side of the film should be in contact with the screen when printing the product.
②The tension of the screen plate selected for the white background spot color film must be above 18N.
③ The positioning sheet must be placed well, and the positioned film and deformation strip must be fixed with transparent tape, and must not be moved.
④For the first exposure, one must remember to turn on the air pump switch, and the exposure can only be done after the air is pumped. The second exposure does not need to be pumped.
⑤ For the second exposure, the side in contact with the substrate should be facing up, and the oil-scraping side should be facing down.
⑥ When developing with a water gun, the water pressure should not be too large (especially when printing some small patterns, the pressure of the water gun should be lowered as much as possible, and the pattern should be opened evenly. Do not hit the same pattern all the time, so as to avoid local stress. A lot of patterns are broken, and the water gun should be shaken evenly and rinsed several times). Only by ensuring the quality of all aspects of screen printing, it is possible to ensure the quality of screen printing, thereby improving the quality of screen printing.
Post time: Jun-13-2023