Printing problems of the most water soluble solid

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The printing problems of water-soluble solid photosensitive resin plates occupy an increasing share in relief printing because of their short plate making cycle, simple operation, printing resistance, resolution, ink transfer performance and so on. It is precisely because of the above advantages and the characteristics of less one-time investment in plate making equipment that the units producing "plate materials" have moved from the original professional plate making factory to Wuhan Automobile New Materials Conference printing factory and self-employed operators. Due to the smaller and scattered use units, most of them have not been trained in plate making operation, so problems often occur due to improper operation in production

first of all, it should be clear that the following problems may be caused by the internal quality of "plates". It can be said that there are inherent deficiencies, so users should first choose products and manufacturers with stable quality. Some users choose to import "plates" in order to avoid the problem of "plates". However, because the imported "plates" have the function of bending circles, it is only suitable for the round pressing printing method. For the round pressing and flat pressing printing, it is best to use the domestic "plates" because the price is only about one fourth of the imported "plates"

I. low printing resistance, word dropping and plate cracking during printing

1. after eliminating the possibility of "plate material" problem, this problem may be caused in the printing process. Resin plate printing belongs to light printing. It is a polymer material, so the prepared plate is more wear-resistant than the metal plate. When looking for pressure on the upper plate, it should be from small to large. If the upper plate is not operated properly, the plate will be pulled during the printing process, and the shear force is too large, resulting in plate cracking and word dropping. Therefore, attention must be paid to the pressure during printing

2. in reality, this problem is mostly caused by plate making. It is because the "drying" link in the operation is not well grasped. There is no problem with the appearance of the finished version, but the hardness of the version is not up to the standard due to the lack of thorough drying. During the printing process, it cannot withstand normal friction, and is quickly ground down, making the graphics and text and pen track "fat", while the printing resistance is greatly reduced, and it cannot be reprinted; Due to insufficient drying, the effectiveness of the adhesive layer between the resin layer and the substrate is reduced, resulting in word dropping during normal printing; Due to insufficient drying, water remains in the resin as small molecules, making the resin layer similar to "soda biscuits", which is very crisp, and a slight pressure will produce cracking. This problem can be avoided as long as the plate making operation is carried out according to the requirements. The drying temperature is 70 ℃ ~ 80 ℃, and the time is more than 30 minutes. For large sub layouts, the time should be extended

II. Word dropping, line bending and word pasting during plate making

1. after the possibility of "plate material" problem is eliminated, this problem is mostly caused by the length of exposure time. Because the thickness of the photosensitive layer of the resin plate is more than 0.85mm, when the exposure time is insufficient, the bottom of the photosensitive layer cannot be fully crosslinked and cured, and there is no trapezoid with large bottom and small bottom formed by light scattering. Therefore, during water development, the trapezoid with large bottom and small bottom is difficult to stand, resulting in word dropping and line bending. In addition, due to plate material or water temperature, the plate washing time is too long, resulting in word dropping and line bending. When the exposure time is too long, due to light scattering, the trapezoidal slope of large bottom and small top is too large, and the plate is pasted

2. this situation is also caused by the "thin, thick, transparent" and positive and negative of the negative film. The exposure of attached negatives is a process of inducing chemical reactions in the photosensitive layer of "plates", so it has strict requirements on the comprehensive competitiveness of the negatives inspection module manufacturers, that is, the light transmission part should be absolutely transparent, and the density should be less than 0.05, and the density of new members in the "10billion" enterprises of Bu Shanying Paper Co., Ltd., Huatai Co., Ltd. and Weida international, which block light, should be more than 3. When the light transmission part is "hazy", it will cause insufficient exposure and word dropping and line bending. When the density of the light blocking part is low, the heavy one will cause no development, and the light one will cause no washing between the lines and paste

when the negative film is reversed and the negative image is not used for plate making, the drug film surface of the negative film is not tightly covered on the photosensitive layer of the plate, but the drug film is wrongly facing up, and a colorless and transparent polyester film layer is separated between the two photosensitive layers. During exposure, the light immediately passes through the polyester film layer after passing through the drug film layer and scatters outward, so the pen tracks of words and lines are equally thickened to produce a paste

3. this problem is caused by the light source. Generally, the photosensitive wavelength area of resin plate is 300 ~ 400 nm, and the wavelength emitted by the light source selected by the user for exposure should mainly be within this area. When the light source is not right, the exposure time is very long, but the word dropping and line bending are still caused by insufficient exposure. After some light sources are exposed, the stroke of the word line appears "shoulder" and the version is pasted. In addition, drying with more floating water after development will also cause word dropping and line bending; The small suction force during exposure can not make the negative and the plate photosensitive layer tightly cover, which will also cause the full version or local paste phenomenon

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