In recent years, the water-soluble solid photosensitive resin plate has the advantages of simple plate making process, low cost, no pollution, good ink transfer performance, high print resistance, light plate material, short plate making cycle, and can be matched with computer laser phototypesetting system. Favored by small and medium-sized printing manufacturers, it is gradually replacing zinc plates.
The photosensitive resin plate is a relief plate material with photosensitive performance, which is made of a synthetic polymer material as a film-forming agent and an unsaturated organic compound as a photo-crosslinking agent. Almost all photosensitive resin plates are irradiated with light (mainly ultraviolet light), and cross-linking reactions occur between the molecules, thereby forming a relief image with some insolubility. The photosensitive resin plate can be divided into solid type and liquid type from the plate making process. The cost of solid series prefabricated plates composed of saturated photosensitive resins is relatively high, but the quality is relatively good, and product packaging, trademark plates, and network line plates can be made; the liquid series consisting of unsaturated polyester resins is Coated plates (simply speaking, it is used to prepare photosensitive liquid for substrate production, and then coated with resin, photosensitive and production) The price is relatively low, suitable for rough text line version. In the actual operation of the solid photosensitive resin plate, the following problems often occur. Only by comprehensive analysis, different treatment, and the root cause of the problem can the problem be solved.
1. Resin version text, lines, pattern lines are too thin and too small, small characters and independent points fall off, small lines are bent in the resin plate making, common problems such as thin lines bending and small text, independent points fall off and so on.
Main reasons: l. Insufficient exposure time of resin plate; 2. Low contrast of film, fog, unclear; 3. Improper baking of resin plate and thermal curing; 4. Low water temperature when brushing resin plate, long rinse time, bristles Excessively hard, too deep brushing; 5. Excessive pressure when printing on the machine, improper adjustment.
Solution:
1. When making resin plates, when encountering small text, lines, patterns, and independent points, you must master the correct exposure time. 3kw iodine gallium lamp, the exposure time is about 20min, it must be longer than the normal version of the exposure time, so that small lines, text, independent points can stand up, not fall off. Due to the long exposure time, the slope of the resin plate produced is small (about 70 °), and the graphic base is firm.
2. When baking resin plates, drying and heat curing treatment, under normal circumstances, the oven temperature is controlled at 60-80 ℃, the purpose is to evaporate the water from the plate; the drying temperature is too high, the resin plate is easy to foam.
3. It is required that the operator's darkroom technology is excellent, and the contrast of the film processing should be as human as possible, no fog, smooth text and lines, and no shortage of pen breaks.
4. When making a solid resin plate, whether it is an automatic plate-making machine or a manual brush-brushing machine, the water temperature should be controlled at 50-60 ° C and rinsed until the substrate is exposed. Brush the resin plate with a rotating brush, and brush the plate on one side only, it is easy to brush the side and slope, causing small lines to bend and fall off; when brushing the plate, choose a brush with soft and suitable hair. If the brush is hard, it will make Small text brushes are damaged; brush resin version should pay attention to master the depth of the brush version. The brush version does not necessarily need to be washed to the bottom. If the brush version is too deep, the text, lines, and patterns on the version will be easily brushed off. In addition, pay attention to the brush Do not rinse the plate too long.
5. When the resin plate is printed on the machine, the pressure between the ink roller and the resin plate, the resin plate and the impression cylinder should be adjusted, and the printing pressure of the resin plate should be adjusted to be smaller than the pressure of the copper-zinc plate and type printing. some. To prevent the ink roller and impression cylinder from crushing the fine text lines of the resin plate due to excessive pressure, affecting its durability.
2. The text and line version are blurred when making the resin version
The main reasons are: 1. Excessive exposure; 2. Vacuum absorption when drying is not true; 3. Film contrast is small and unclear.
Solution:
1. Master the exact exposure time of the resin version, especially the hollow text and lines are the easiest to paste, and make the graphics and text as thick as possible when designing.
2. The suction of the printing machine should be firm. If the suction is not true, there is a gap between the resin plate and the film, and ultraviolet rays will be injected from all around, causing photosensitive paste.
3. Before printing, carefully check whether the apricot film is pasted. Good light transmission, contrast, and clarity can meet the needs of plate making quality.
Third, the resin version is not washed
The main reasons: l. The plate material of the resin plate has exceeded the shelf life, or light leakage during production, storage, and transportation, the resin plate is photo-hardened; 2. The water temperature is too low when rinsing and brushing; 3. The film darkroom treatment is not good, The film has poor light shielding and low density.
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