Efforts should be made to reduce the use of powder

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Efforts should be made to reduce the use of powder spraying in printing

in printing, powder spraying is used to prevent the back of the product from rubbing dirty. Now many advanced printing equipment have eliminated the powder spraying device and adopted three groups of drying methods, namely, two groups of infrared and one group of ultraviolet. At present, most of our domestic printing equipment are infrared plus powder spraying or only powder spraying devices

usually in production, when the ink layer is thick and the dark tone area is large, the printing operator always hopes to put the powder amount more, so that the product will not be scrapped because the back is rubbed dirty, but often ignores the problem that the powder amount should be as small as possible. In fact, too much powder will also bring a lot of harm

1. If the amount of powder is too large, it will directly affect the shift output when printing the reverse side due to the excessive amount of powder on the front side. In severe cases, the blanket needs to be cleaned every hundreds. Therefore, the ink color of the product will be unstable, which will not only affect the quality but also affect the output

2. Too much powder will affect the gloss of the product. When printing some high-end products, operators always hope that the ink saturation is higher. In this way, the development of the advantages of the recycled plastic granulator is analyzed. The printed products are bright and bright, and the amount of powder is increased to prevent dirt. The powder spray is absorbed by the ink on the ink layer that has not been dried, which will form a layer of fog on the color, and the gloss of the product will be reduced

3. Excessive powder will cause serious wear and tear to machinery and equipment. During production, while spraying powder into products, a considerable amount of powder flies to the paper receiving chain, paper teeth and rollers of the machine. Although there is maintenance time every week, it may not be able to clean up all the dust, and the wear of the machine will inevitably increase over time

4. Too much powder will also have a certain impact on the health of the operator. Although the salesperson said that powder spraying was harmless to human body, the operator stayed in the workshop with fine dust flying every day, and his lungs did not know how much dust to breathe

5. Too much powder will also affect the post process processing, such as glazing and film covering

therefore, in production, we should pay enough attention to the use of powder spraying, and try to spray less or no spray to achieve the purpose of controlling the dirt on the back. There are many factors that cause the back to rub dirty in production, and the key is how to effectively control it

1. Strictly control the density value. The value of each color density is obtained by sampling and observing its K value "In recent years, the best value is the point expansion value and the saturation of ink. In another sense, the best value (density) obtained by this method" It is also the best amount of ink that the paper can bear. For example, the best density values obtained by using 128 grams of Japanese coated paper are yellow 1.05, red 1.35, blue 1.45, and black 1.70. We can keep this data for printing in production. Under normal circumstances, it is impossible to get dirty. It will be safer to add a small amount of dusting. But the density is too high, even if the ink layer is not thick, it will still rub dirty. For example, compared with the four-color dark tone overprint, the yellow and magenta overprint with 100% overprint respectively are obviously not thick. If the Yellow density value is increased by more than 1.30 and the magenta density value is increased by more than 1.50, which exceeds the critical value of the ink capacity of the paper, the product is easy to rub the back dirty

2. The reason why we use powder spraying is that the dark tone area of the product is large and the ink layer is thick. In case of such originals, we should use plate making means and adopt the background color removal method to reduce the thickness of the darkened ink layer on the premise of trying not to lose the importance of the original darkening. The ink volume is controlled at 235% - 270%, but the all glass long fiber material can not provide sufficient stiffness. Compared with the traditional method, the total ink volume is reduced by 1, and the production capacity of acrylic resin for optical materials is increased by 25% - 90%. This can not only ensure the density requirements of dark tone, but also prevent the influence of intermediate dark tone level due to excessive ink reduction. According to relevant data, the total ink volume 235% and the total ink volume 360% reduce the ink volume 125%, and the displayed density value is basically similar. When the total ink volume of the actual dark tone is 235%, the printing can be controlled without powder spraying or a small amount of powder spraying

3. The sample is the customer's credential and the basis for printing. If the printed product is too different from the sample, the customer will politely refuse to accept it. The problem is whether the sample truly reflects the original. For example, the ink layer on the original is not so thick. When proofing or signing, in order to meet the user's satisfaction, we desperately increase the amount of ink. This will cause serious point expansion, which is the diffusion from the center to the surrounding, and the ink in the center will certainly exceed the amount borne by the paper, so it is difficult to avoid getting dirty without increasing the amount of powder

4. Ink emulsification will seriously affect the drying time of products. When the ink contains a certain amount of acidic aqueous solution, it will prolong the time of oxidation conjunctiva on the imprinted surface, resulting in slow drying, which is easy to cause the back to rub dirty. There are many factors that cause serious emulsification of ink, but the most important is water. At the same time, we should control the ink load. When reaching a certain density value, we should use the least amount of ink and the least amount of water, which is the best way to control the serious emulsification of ink

5. The printing pressure is too light, so that the ink cannot be transferred normally. The ink transferred to the paper cannot be well combined with the paper. The ink just floats on the surface of the paper, which is not firm, and will also cause the back to rub dirty. Therefore, the printing pressure should be appropriately increased within the normal range of point expansion

to sum up, in order to control the dirt on the back with less or no powder spraying, we must carry out serious process research from the original, formulate an effective process construction scheme, and make the original and standard samples suitable for printing by means of plate making. During printing, we should strictly follow the data-based operation, control the density value of various colors, pressure and ink balance, maintain a certain printing speed, appropriately increase some dry oil, and reduce the stacking height of semi-finished products

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