1. In the process of exposure, light scattering and diffuse reflectance are different. When an ordinary flexographic printing plate is exposed, the ultraviolet rays pass through the vacuum layer, the film base, the emulsion layer, and the anti-halation layer. The total thickness is large, and there is severe scattering and Diffuse reflection problem. However, when the digital flexographic printing plate is exposed, the light passes through only a layer of black coating less than 0.001 in., and there is only a slight scattering and diffuse reflection phenomenon.
2. The exposure environment is different. Ordinary plates are exposed under vacuum conditions, while digital plates are exposed in the air. The mechanism of photopolymerization of photopolymerized photosensitive resins in air and in vacuum is different, resulting in different dot shapes, exposure latitude, and other properties of the printing plate.
3. Dots are different, the dot reproduction range is large, the cross-section of the raised dots on the general flexographic printing plate is circular, the longitudinal section is trapezoidal, and the top of the dots is flat, while the dots on the digital flexo plate are small and slanted. The degree is smaller, the top of the point is round but not flat. The digital flexo version has a smoother edge. The outlines of the edges of ordinary flexo printing plates are clear. Contoured dots are easy to break when printing, and dots on digital flexo printing plates, especially high light spots, are not easy to appear, so the printing quality is good.
4. With different exposure latitudes, the black coating on the digital flexo greatly improves the latitude of the UV main exposure. Experiments show that the digital flexo version of the main exposure time increased by 5 ~ 10min, on the printing plate image part of the raised height without any effect, while the ordinary flexo version is different, as long as the exposure time has increased slightly, it will make the graphic convex The starting height is significantly reduced. Large exposure latitude favors perfect dot shape.
Because digital flexographic printing plates have a certain degree of exposure latitude, no special attention should be paid to highlights and dark spots during exposure, and high light spots are not lost. It is recommended to set the main exposure time of the digital flexo version to 10 minutes, which is enough to ensure that the highlights are not lost. In the preparation of ordinary flexographic printing plate, it is necessary to strictly control the exposure time, not only to pay attention to high light spots are not lost, but also take into account the dark spots do not paste.