Screen printing process technology and detailed operation (5)

V. Direct Diaphragm Screen Printing

Direct diaphragm market, direct diaphragm and indirect diaphragm structure is basically the same, but the coated sensitizer is diazo sensitizer, direct diaphragm is supported by PET film, diaphragm base will not be deformed, flatness is very it is good.

The process of film formation of the direct film is a cutting film → transfer film → film lamination → drying → exposure → development → washing → drying → sealing.

1. Diaphragm repost

Diaphragm transfer is to put the cut direct film emulsion layer up on a flat surface, wet the screen with veneer on both sides, lift up the wetted screen plate, and turn the screen printing surface down. Slowly place it on the direct diaphragm and place the diaphragm in the middle of the screen. Scrape the mesh with the scraper, so that the water passes through the mesh so that the screen surface is in close contact with the emulsion layer of the direct diaphragm. Use a newsprint or a clean flannel to draw moisture from the squeegee side.

2. Laminated thickening

The screen printing product has a thick ink layer and a strong three-dimensional effect, which is far more than offset printing, flexo printing, and gravure printing. This is mainly due to the ease of control of the screen thickness and the film thickness. The advantage of the direct diaphragm is not the level of printing, but rather the three-dimensional strong fine graphic printing, so only by the increase in the thickness of the ink layer can not be achieved, the need to use lamination to increase the thickness of the version of the film.

After the film is dried, the screen plate is dried and the film is placed in a sink. The screen is placed in the sink with the printing surface facing upward. The water is immersed in the screen for about 25 cm. Another direct film is immersed in water with the emulsion layer facing down. Press on the screen plate, then put the screen plate out of the sink, scrape the printing surface with a scraper, so that the moisture and air between the two layers of the film overflow, and then use sponge or paper towel to absorb water, so as to increase The thickness of the plate. Laminating is the advantage of the direct diaphragm method. It has the characteristics of thick and uniform film thickness. It can not only obtain the thick film version of the screen plate for direct legal use, but also can obtain the same screen plate as the indirect film method. Ink uniformity.

3. exposure

The direct diaphragm method is the same as the indirect method. The exposure is performed after the plate is formed on the surface of the screen. When the direct diaphragm method is used to print, there is a slight gap between the screen and the film, which affects the accuracy of the exposure. Sexuality has an impact on the quality of screen images.

The exposure operation, the position of the printing film and the printing film must be correct, and the light transmission order is the printing film base → the printing film emulsion layer → the printing film system. The emulsion layer of the printing film is close to the printing surface of the screen, so as to reduce the scattering phenomenon of the photosensitive film exposed by the light source to reduce the latent corrosion of the photoresist.

4. Development and washing

The direct diaphragm method uses a diazonium salt emulsion, and the direct diaphragm is exposed. Its non-photosensitive cross-linking component can be dissolved in water, so the development can be directly used with water.

The direct diaphragm is blocked by the wire mesh. If the flushing ear listens to too low pressure, the smear particles will clog the mesh, and it is difficult for the purple to flush the surface to meet the requirements of the printing plate. Direct diaphragm development requires a high pressure water jet to rinse with strong water.

5. dry

The direct membrane method and the indirect membrane method dry the same, but some aspects should be noted. Laminated direct film, if not completely dry, will cause the interlayer adhesion to weaken, leading to exposure in the photographic method if the screen is not fully dry, the sensitivity of the photosensitive adhesive will decline.

6. Closure

The sealing net is to block the non-inking screen mesh on the screen plate with the glue liquid. When the printing plate is inked and printed, the ink will not leak out and cause the printing product to be contaminated.

Screen printing is a complicated task, and many factors affect the quality of the printing plate. In the plate making, we must strictly follow the manufacturer's plate-making materials, such as the use of the degreasing grinding agent and the application requirements of the sensitization chest. At the same time, it must be matched with all the mesh fabric variables. Such as the height of the screen mesh, the thickness of the wire diameter, the size of the screen opening area; the material of the frame, the size of the frame and the strength of the frame; the selection of the angle and tension of the stretch net, the frame and the screen Adhesive method; Sensitivity and resolution of the photosensitive adhesive, Adhesion of the photosensitive adhesive, Stretch rate, Hardness, Thickness; Solvent resistance and rub resistance, and sensitizer loading time and blending time, photosensitive coating Cloth method, drying method, drying temperature and humidity and drying time; printing plate type light source and type, exposure distance of light source, exposure time, developing method, developing temperature, developing time and the like are all related to the printing plate resistance.





Source: Screen Printing Information Network