Analysis on the key points of using photosensitive

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Analysis on the key points of using photosensitive emulsion in silk screen printing

at present, diazo photosensitive emulsion (diazo sensitizer) used in silk screen printing is an ammoniate, which is harmless to the environment and suitable for green printing, so it is widely used. The advantage of temperature shock test of diazo photosensitive emulsion gjb150.5 is that the coated template is stored for a longer time, which is conducive to environmental protection. To make a good direct emulsion template, one of the most important elements is that the photosensitive adhesive layer of the template must be uniform. The emulsion should be completely covered with silk, and the adhesive layer on the printing surface of the template should be thicker. The printing surface of the template shall be glued for 1 ~ 2 times, and then immediately glued for 2 ~ 4 times on the ink scraping surface, wet to wet, and then dried. After drying, apply 1 ~ 2 times on the printing surface to make the photosensitive adhesive layer reach the final required thickness. Each gluing must be carried out after the previous glue layer is dried

the number of stencil gluing is divided into two parts when setting parameters. The decisive factors are the requirements of printing and the fineness of silk. In most cases, the main adhesive layer should be wet to wet coated. After each layer is dried, TORLON reg; Pai combines the outstanding performance of thermosetting polyimide and the advantages of melting processing of thermoplastic, and then adds the coating of photosensitive adhesive layer to eliminate the unevenness caused by silk structure

the quality and fineness of silk is another important factor that determines the coating times of the main adhesive layer of the template, because the friction pair directly determines the usefulness of this equipment. The percentage of opening area of wires with similar thickness varies greatly. A larger aperture requires more emulsion to pass through the hole for each coating. In order to get the same adhesive layer thickness for the silk, different coating times are required. The thickness of the glue coating is also different for the wires with the same mesh number and different quality, because they not only have different pore diameters, but also different wire thicknesses. Therefore, the number of gluing is also different. Gelatinization should be carried out immediately after degreasing the version to prevent the version from being contaminated with dust again, unless the degreased version is stored in a dust-free environment

the version must be completely dry when gluing. Manual gluing usually uses a squeegee. The blade of the squeegee must be very smooth and cocked up in the whole length, so as to ensure the uniformity of the whole coating, even in the center of the plate. Because many diazo sensitizers and their sensitized emulsions have strong acidic reactions, a non oxidizing scraper made of plastic should be used, and the aluminum scraper is easy to be damaged. The metal plating scraper will oxidize in a short time, and then destroy the components of the photosensitive lotion. At this time, fine foam and scum will appear in the emulsion. If the photosensitive emulsion is stored in a stainless steel or aluminum scraper, a similar phenomenon will occur after a few hours. Once foam or scum appears, the photosensitive emulsion can no longer be used. Special attention should be paid to that the emulsion should not be placed in the scraper for too long. When placing, the emulsion must be covered to avoid falling into dust or drying

for printing requirements, there are mainly the following points. ① Line. Printing materials with high definition are required to use 90 mesh/cm or finer silk. The thickness of the photosensitive adhesive layer on the wire should be 10 m ~ 18 M. Generally speaking, the thickness of the photosensitive adhesive layer is about 15% - 25% of the thickness of the silk. ② Halftone. Halftone printing requires a thin ink layer, so the photosensitive adhesive layer is also very thin, about 4 m ~ 8 m, and the thickness of the photosensitive adhesive layer is about 10% of the thickness of silk. ③ UV ink. Nowadays, UV ink is often used in packaging and printing. When printing, we should pay attention to the minimum amount of ink adhesion. Generally speaking, the photosensitive adhesive layer on the printing surface of the template should not exceed 5 m

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