Photosensitive resin plate detailed introduction
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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 printing durability, light plate material, short plate making period, and can be matched with a computer laser phototypesetting system. It is favored by small and medium-sized printing manufacturers and is gradually replacing the zinc plate.
The photosensitive resin plate is a relief plate having a photosensitive property obtained by using a synthetic polymer material as a film forming agent and an unsaturated organic compound as a photocrosslinking agent. Almost all photosensitive resin plates are subjected to cross-linking reaction between molecules under the irradiation of light (mainly ultraviolet light), thereby forming an embossed image having a certain insolubility. The photosensitive resin plate can be classified into two types, a solid type and a liquid type, from the plate making process. The solid type prefabricated plate made up of saturated photosensitive resin is relatively high in cost, but the quality is relatively good, and it can be used to make commodity packaging, trademark plate, and screen pattern; the liquid type series composed of unsaturated polyester resin is The coated plate (in short, it is prepared by reconstituting a photosensitive liquid for base preparation, then applying resin, sensitizing and making), and the price is relatively low, and it is suitable for a rough text line version. In the actual operation of the solid photosensitive resin plate, the following problems often occur in the process of plate making. Only comprehensive analysis, differential treatment, and identification of the root cause of the problem can solve the problem.
First, the resin version of the text, lines, lines of the pattern is too thin, too small, small characters and independent points fall off, small lines curved
In the resin plate making, it is common to have problems such as thin lines and small characters, and independent dots falling off.
The main reasons are: l, the resin plate exposure time is insufficient; 2, the film contrast is small, there is fog, unclear; 3, baking resin plate and heat curing improper treatment; 4, brush resin plate when the water temperature is low, long washing time, bristles Too hard, the brush version is too deep; 5, the pressure on the machine is too large, the adjustment is not appropriate. Solution:
1. When making a resin plate, when you encounter 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 extended than the normal version of the exposure time, so that small lines, text, independent points can stand, do not fall off. Due to the long exposure time, the slope of the resin-coated side of the resin plate is small (about 70°), and the base of the image is firm.
2, baking resin plate, drying and heat curing treatment, under normal circumstances, the oven temperature is controlled at 60-80 ° C, the purpose is to evaporate the water on the plate; the drying temperature is too high, the resin plate is easy to foam.
3, the operator is required to have a hard technical darkroom, the contrast of the film processing should be as close as possible to people, no fog, text, lines smooth and smooth, no shortage of strokes.
4. When making the solid resin plate, whether it is automatic plate-making machine or manual brushing, the water temperature should be controlled at 50-60 °C, and rinse until the substrate is exposed. Brush the resin plate to rotate the brush, single on one side of the plate, it is easy to brush the side and slope, causing the thin lines to bend and fall off; when brushing the plate, choose those soft and suitable brushes, if the bristles are hard, it will make Small text brush falling damage; brush resin version should pay attention to master the depth of the brush, the brush version does not have to be washed to see the base, the brush version is too deep, the text, lines, patterns on the plate are brushed off the plate, in addition, pay attention to the brush The rinsing time should not be too long.
5. When the resin plate is printed on the machine, it is necessary to withstand the pressure between the ink roller and the resin plate, the resin plate and the impression cylinder, and adjust the printing pressure of the resin plate to be less than the pressure for adjusting the copper-zinc plate and the letterpress type. some. To avoid excessive pressure, the inking roller and the impression cylinder crush the fine text lines of the resin plate, which affects the printing durability.
Second, the text, line version is blurred in the resin version
The main reasons are: 1. Excessive exposure; 2. Vacuum adsorption during drying is not true; 3. The contrast of the film is small and unclear.
Solution:
1. Master the exact exposure time of the resin plate, especially the hollow text and lines are the easiest to paste, and the design should be as thick as possible.
2. the printing machine to inhale to be strong. If the inhalation is not real, there is a gap between the resin plate and the film, and the ultraviolet rays will be injected from all sides, resulting in a photosensitive paste.
3. before the printing plate to carefully check whether the apricot film is paste, light transmittance, contrast, clear, in order to meet the needs of plate quality.
Third, the resin version does not move
The main reasons: l, the resin version of the plate has exceeded the shelf life, or leakage during the production, storage, transportation process, resin plate photosensitive hardening; 2, the water temperature is too low when washing the plate; 3, the film dark room is not well treated, The film has poor opacity and low density.