Efforts should be made to reduce the amount of dusting used in printing

In printing, dusting is used to prevent dirt on the back of the product. Nowadays many advanced printing equipments have eliminated powder spraying devices and use three-group drying methods: two sets of infrared and one set of ultraviolet. At present, most of our domestic printing equipment is infrared plus powder or only dusting devices.

Often encountered in the production of thick ink layer, dark tone when the area, the printing operator always want to put a large amount of powder, so that the product will not be scrapped because of the back of the dirty, but often ignore the amount of powder should be May be small this problem. In fact, too much powder can cause a lot of harm.

1. When the amount of powder is too large, when positive and negative printing is performed, the amount of powder on the front side is too large, which will directly affect the output of the class on the reverse side. In severe cases, it takes a few hundred sheets to clean the blanket. The product will also appear unstable ink, affecting quality and affecting yield.

2. Too much powder will affect the gloss of the product. When printing some high-end products, the operator always hopes that the ink color saturation is higher. The products printed in this way are both bright and shiny, and at the same time they increase the amount of powder in order to prevent dirt. The dusting is absorbed by the ink on the ink layer that has not been dried, and a layer of fog is formed on the color, and the gloss of the product is reduced accordingly.

3. The amount of powder is too large and the wear on the machine equipment is severe. In production, while spraying powder, a considerable part of the powder goes to the machine's delivery chain, grippers, and rollers. Although there is maintenance time every week, it may not be able to clean up all the dust. It will inevitably increase the wear on the machine over time.

4. The amount of powder is too large and it will have a certain influence on the health of the operator. Although sellers say that dusting is harmless to the human body, the operator stays in the dusty workshop every day and the lungs do not know how much dust to inhale.

5. The amount of powder is too large, it will also affect the post-process processing, such as light coating.

Therefore, in the production, we should pay enough attention to the amount of dusting, spraying or spraying as little as possible to achieve the purpose of controlling the dirt on the back. There are many factors that cause back-scratching in production. The key is how to effectively control it.

1. Strictly control the density value. The value of each color density is obtained by proofing the K value, dot gain value, and ink saturation to obtain the best value. In another sense, the best value (density) obtained with this method is also the best amount of paper to withstand the ink. For example, the best density values ​​we obtained with 128 grams of Japanese coated paper are yellow 1.05, red 1.35, blue 1.45, and black 1.70. We can maintain this data in production and print it. Under normal circumstances, it is impossible to pick up dirt, and adding a small amount of dusting will be more secure. However, if the density is too high, even if the ink layer is not thick, it will be dirty. For example, compared with 100% superimposition of yellow and magenta and four-tone superimposition, it is obvious that the 100% ink layers of yellow and magenta are not thick. If the yellow density value is increased by 1.30 or more, the magenta density value is increased by 1.50 or more. Exceeding the critical value of the paper to withstand the ink, the product is very easy to back dirty.

2. We use dusting because the product has a dark shadow area and the ink layer is thick. In the face of this type of manuscript, under the premise of not losing the tone of the original manuscript as much as possible, we should use the plate-making method and adopt the color removal method to make the dark ink layer thinner. The amount of ink is controlled between 235% and 270%, which is 125% to 90% lower than the total amount of ink in the conventional practice. This will not only ensure dark tone density requirements, but will not affect the darkness due to excessive ink reduction. Levels. According to relevant data, the total ink volume of 235% and the total ink volume of 360% reduce the ink volume by 125% and the displayed density values ​​are basically similar. While the actual dark adjustment of the total ink volume is 235%, the printing can control the back scumming without spraying powder or a small amount of dusting.

3. Samples are the customer's credentials and are the basis for printing. If the printed products and proofs are too large, customers will refuse to accept it. The problem is whether the proofs actually reflect the original. For example, the ink layer is not so thick on the original, and the ink volume is desperately increased in order to meet the satisfaction of the user in proofing or signing. This will result in a serious expansion of outlets, and the expansion of outlets will spread from the center to the surroundings. The ink at the center will exceed the amount of paper it is subjected to. It will be difficult to avoid dirtying without increasing the amount of powder.

4. Ink emulsification seriously affects the drying time of the product. When the ink contains a certain amount of acidic aqueous solution, the time for oxidative conjunctiva on the surface of the blot will be prolonged, resulting in slow drying and easy backside smudging. There are many factors that cause severe emulsification of the ink, but the most important thing is water, but also control the amount of ink loaded. When a certain density value is reached, the minimum amount of ink and the minimum amount of water should be used, which is the best way to control the severe emulsification of the ink.

5. Printing pressure is too light, so that the ink can not be transferred normally. The ink transferred to the paper cannot be combined well with the paper. The ink just floats on the surface of the paper and is very weak, which can also cause the back stains. Therefore, in the normal range of network expansion, printing pressure should be increased.

To sum up, we need to use less or no powder to control the back of the dirty, we must start from the manuscript to carry out serious process research, develop an effective process construction program, through the plate making method to produce the original printing and Standard proofs. In the printing, we must strictly follow the data operation, control the color density values, pressure and ink balance, maintain a certain printing speed, properly add some dry oil, and reduce the height of semi-finished products.