Analysis of the reason why the overall ink color becomes lighter during the printing process
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At the time of printing, the surface ink of the finished product becomes very shallow, and the white stains seem to be related to the lack of ink, but the amount of ink is not adjusted, and the water consumption and blanket on the printing machine are treated. Still can't. Ask me what is the reason for that, and what should I do?
First, from the analysis of the printing plate, nothing more than the following four aspects
1 The impact of raw materials
The quality of the PS version used in the printing plate is of utmost importance, especially in the PS versions produced by some small factories, who will cut corners on the recipe. For example, the ratio of photosensitive glue to water is seriously out of balance, and the raw material concentration of the ingredients is often too diluted, so it has a certain influence on the printing quality, such as the strength of the ink reduction (lower performance) and the reduction of printing durability. The PS version produced by regular manufacturers rarely occurs in this aspect. If a similar situation occurs, the PS version should be replaced immediately and it will not be used.
2 the impact of the quality of the bottom plate
In the imposition, you must first check whether the texture density of the bottom plate used is satisfactory, and whether the surface of the bottom plate is a positive or negative word (commonly used words are reverse words). If the density of the bottom mesh is too light, it will affect the exposure time and development intensity. Because the density of the bottomographic texture is too shallow, the ultraviolet light can directly penetrate the photosensitive layer of the surface of the PS plate through the textured surface during exposure, so that the photosensitive layer is damaged to varying degrees. During development, the damaged photosensitive layer will be developed to varying degrees, making the ink-repellent part hydrophilic, which will reduce the amount of ink used, and the ink will be diluted by water to varying degrees (the water will rise from this time). To the effect of dilution, similar to a kind of lightening agent), the printed printed matter will naturally be white in color. If the words on the bottom plate are positive, the imposition must be literally attached to the surface of the base used for the imposition. When the printing plate is dried in this way, the contact distance between the surface and the photosensitive layer of the PS plate is invisibly increased. Therefore, when exposed, the ultraviolet light can be transmitted through the middle of the distance to a certain extent, so that the photosensitive layer which should be retained on the PS plate is damaged. The damaged part during development will be developed or not fully developed. From the surface, the part will appear faint or lighter, let alone print.
Sometimes, due to mistakes made by the operator during the imposition, the layout is reversed, or when the printing plate is printed, the assembled version is reversed. In this case, the sensitization of the surface and the PS version may occur. An extra distance is formed between the layers. In this way, after exposure and development of the printing plate, the entire part of the printing surface will be faint. If the above similar situation occurs, the error should be corrected in time. If the bottom plate is not suitable, it should be re-sampled; if it is reversed or reversed, it should be re-spelled or re-released and placed in the right position.
3 actual operational impact
When the PS version is exposed and developed, the operator should handle it according to the actual situation, and it should not be uniform. The exposure time is relatively shortened or extended to prevent unnecessary damage to the photosensitive layer of the ink-receiving portion. After exposure, when the PS plate is developed, the operator should concentrate and the formulated developer should be treated differently depending on the situation. The development time should be well controlled. If the head is over, the photosensitive layer of the ink-receiving part will be damaged to varying degrees, and the lighter performance will be greatly reduced. Therefore, the printed matter will appear to have insufficient ink on the entire layout, which appears white stains. If this happens, the basic skill level of the operator should be improved.
Second, from the ink used in printing and printing machine analysis
Before printing, the operator should check the ink used for printing. Do not look at the ink is just bought, the quality of printing can not be guaranteed. Because some ink manufacturers now have different ink processes. Some inks must be stored for a certain period of time, and the hue can be used to achieve the best results, and some must also add a certain amount of auxiliary materials. If the storage period is insufficient, the amount of ink can not achieve the best effect, so the printed ink color must be unsatisfactory, and there is no shortage of white color. If the storage period is too long, beyond the shelf life, such ink can not be used, its ink color is erratic, the hue is unstable, it is difficult to blend well. Not to mention the quality of printing?
At the time of printing, the machine was started and should not be printed immediately. Otherwise, due to uneven ink, the ink will appear uneven in ink. Instead, the ink should be played for a while. After the roller is continuously transferred, the ink-retaining parts on the printing plate are fully inked, and then the proofing or printing is started. During the printing process, the amount of ink used and the amount of water should be appropriately adjusted. If the water consumption is too large, the water will act as a light-reducing agent, thereby reducing the amount of ink used, and lightening the ink color of the ink to make the entire ink lighter. The blanket on the press should be wiped clean and kept clean at all times. Generally speaking, when the surface of the blanket is smooth and clean, the dots are not easily lost, and the ink layer coverage is good. When the surface is rough and not clean, the printed dots will be irregular. Or when the surface layer of the blanket forms a very smooth aging film due to light, heat and long use time, it will completely cover the surface of the blanket, which will increase the hydrophilic property and reduce the ink affinity. The printed ink is whitish. If a similar situation occurs, stop the machine immediately, clean or replace the blanket.