Color Printing Product Dirty Situation Analysis and Preventive Measures

Blotting (ie, smearing) is a process failure that can easily occur in color printing products. The occurrence of such failures will affect the appearance quality of finished products, and it will result in mass scrapping of products, which will bring great losses to the company's economy and reputation. There are many reasons that cause the product to become dirty. Thickness caused by the printing ink layer, but also the back of the paper smooth and easy to cause the bottom; the reasons for the characteristics of the ink, but also with the temperature and humidity of the environment; there are improper adjustment of the ink process, there are layout printing pressure discomfort, etc. Wait.
First, the thickness of the printing ink layer caused by improper thickness of the back of the product is currently determined that the printing ink layer is moderate or not, generally only by virtue of experience to visually grasp, mainly to press uniform printing process, as well as the layout by the ink evenly reach the bottom, not False printing, the hue and the sample draft are the main criteria for determination. Due to non-uniform or insufficient printing pressure, poor glossiness of printed paper, darkness of printed originals, and hue of printing inks, there are insufficient understandings, which can easily lead to inaccurate determination of printing ink layers. If we blindly increase the amount of ink to satisfy the aesthetics of the printed ink on the printed page, the back of the product will become dirty due to the thick ink layer.
Second, we must correctly understand the relationship between the printing pressure and the thickness of the ink layer Theory and process practices have clearly shown that moderate pressure is an important condition for uniform transfer of the ink layer layout, when the layout pressure is insufficient or uneven, it will inevitably affect the layout of the ink layer Transfer evenly. Printing process practice can show such a situation, when the layout pressure is slightly insufficient or uneven, the ink on the layout of the print appears to be flowering, the ink thickness of the entire layout is not consistent enough, and by increasing the amount of ink, the ink is printed. That is, it appears to be thick, and the phenomenon of blooming of the layout is immediately eliminated, and the degree of aesthetics of the printed layout is also improved. It can be seen that the thickening of the printing ink layer can compensate for the poor contact between the ink layer and the substrate caused by insufficient printing pressure and eliminate the phenomenon of printing and flowering. However, this can easily cause the printing material to be dirty. On the contrary, the printing pressure is adjusted to a sufficient level, adjusted evenly, and the amount of ink on the layout is appropriately thinned. The printed product will not produce flowers, and the ink layer will appear firm and even, and the product will be less prone to stickiness. Therefore, color printing products should first adjust the printing pressure, then adjust the layout of the ink, the printing effect is better.
Third, to deal with the relationship between the printability and the thickness of the ink layer In the process of printing, if the lack of a correct understanding of the printability of various types of paper, so that the amount of cloth is not properly grasped, but also easily produce a dirty print . Paper with poor paper smoothness penetrates fast to the ink and has a large amount of ink. When printing such paper, if the layout pressure is insufficient or uneven, it will easily appear under the printing after printing. When the paper is made up to increase the amount of ink supply, due to the thick ink layer on the layout, the drying speed of the printing is slow. It is prone to the problems of printing and sticking. Therefore, for papers such as offset offset paper, where the paper surface is slightly inferior, the printing pressure should be increased accordingly. For papers with better paper smoothness, such as coated paper and glass cards, good print transfer can be achieved with proper printing pressure. Therefore, the printing ink layer should be as thin as possible so that the chance of imprinting is too low. At the same time, from the viewpoint of stickiness, the printing of large-area drawings should adopt the “deep ink thin printing” process principle, that is, the color of the printing ink should be slightly darker, and the printing ink layer should be thinner accordingly, which not only satisfies the printing hue requirements. , And to achieve better anti-sticking purposes.
Fourth, we must grasp the relationship between the properties of the printing plate and the thickness of the printing ink layer The practice of letterpress printing clearly shows that the quality of the printing plate has a great relationship with the printing thickness of the ink layer and the printing pressure. That is, the smoothness of the printing plate is poor and the printing needs The ink layer and pressure are large, and vice versa. For example, printing zinc plate material, due to its poor ink affinity and poor layout smoothness exists, only by increasing the printing pressure and the ink layer thickness, can make up for the defects in the characteristics of the plate material, to achieve a full process effect of the printing ink layer, but These are extremely prone to bad printing and sticking, so it is not advisable to use color printing products with open format for zinc printing. The resin plate material has good surface glossiness, soft texture, flatness, and good ink receptivity, and its printing ink layer is correspondingly thinned, so that a satisfactory printing effect can be achieved, and printing and stickiness are less likely to occur. opportunity. Therefore, printing large-area plates with resin printing, better anti-sticking effect.
5. Improper operation of the printed product caused by improper process technology 1. Improper adjustment of the ink roller device, excessive ink volume, and non-uniformity caused by the ink stickiness of the printing plate. The ink layer of the printing ink can maintain the thickness appropriately and evenly. The accuracy and quality of the rubber roller, as well as the correct position of the ink roller, are the key factors. When the ink roller head, shaft hole due to wear appear large gaps or biased core situation, and the ink roller colloid is too hard, out of round, lack of good elasticity and viscosity, etc., so that the ink roller along the layout scrolling brushing process In the case of non-uniform contact with the layout, it is likely to result in partial ink brushing unevenness and thinning of the ink layer. This is an aspect. On the other hand, if the ink roller is too high or too high, and the ink roller and the iron roller have uneven contact, it is easy to make the ink layer of the plate insufficient or uneven. In order to overcome the shortage or inconsistency of the ink supply on the layout, ink will cause a partial thicker layer of the ink on the layout and cause the product to become dirty. Therefore, printing large-area plate products, the ink roller device with high accuracy, the rubber roller core is better, the soft and hard gel should be appropriate, the ink roller height adjustment should be accurate, and the string of iron roller to maintain a uniform contact state, In order to ensure the normal transmission of ink and cloth, thus reducing the chances of printed materials appear dirty.
2. Dirty product caused by improper delivery. When the machine picks up the printed sheets and sends them to the delivery table, if the angle and height of the paper (paper drop) are uncomfortable, the upper and lower sheets may be rubbed and the bottom situation may occur. Such as the DT400 type four-automatic platform printer's delivery structure, should see the print format, paper hardness and softness, and accurately adjust the angle and height of the paper, otherwise, the paper can easily wipe the edge of the paper to the previous print imprint , make the print layout ink damaged. Therefore, when the machine presses the sheet, it should be adjusted so that the printed sheet is suitable for paper feeding to prevent the printed product from getting dirty. In addition, the method of taking paper and airing is also an important part of product anti-sticking. The paper should be taken lightly and gently to prevent sticking. When picking up the paper, the back of the printed sheet can not be supported by the back of the finger with the support of the back to prevent the product from being pressed by the finger. Each stack of printed sheets should be treated with ink according to the condition of the printing plate surface, and the quantity should be grasped as appropriate to prevent the product from being over-pressed.
3. If the plywood is used as the printing plate base, the plywood material is not solid, and the compression deformation coefficient is large, only by increasing the printing pressure and the ink layer thickness. To overcome the defects in the bottom tray, it is bound to make the prints dirty. Therefore, the printing of plate-plate products containing solids should adopt magnetic platen or other metal underlays, which can achieve a relatively flat and constant printing pressure, so that the printing ink layer is thin without flowering, which is conducive to anti-sticking.
4, the paper is acidic and humid climate, so that the prints are not easy to dry and cause sticky, such as the use of Plastic sheet paper or some domestic coated paper printing plate products, due to the thick printing ink layer, plus the acidity of the paper is not easy to make the ink layer dry Imprinting has occurred. In this case, attention should be paid to the proper addition of desiccant oil in the ink to promote the timely drying of the oxidized conjunctiva in the ink layer so as to prevent the printed product from getting dirty.
5, knock paper crease caused by the printing of paper friction over the bottom of the coated paper, due to the smoothness of the paper surface, if the paper crease trace knock highlights easily scratched with the imprint and produce the bottom situation. Therefore, knocking on paper should be based on the structure of the layout, the characteristics of the paper as appropriate to master the way to knock paper. For thicker coated paper that has curling conditions, it should not be knocked on as much as possible, and only the rubbing or kneading method should be used to knead the paper straight and firm to avoid over-imprinting. (From "China Packaging News")