Correct Handling of Quality Problems in Carton Preprinting (Part 2)

1, the ink drying is bad. If the ink is dried too fast, it will cause the phenomenon of early conjunctiva formation in the ink layer, and the ink may be unevenly colored and the paste may be damaged during printing. This is mainly due to the excessive use of dry oil in the ink and the excessive drying of air humidity. For the above reasons, the ink is crusted on the ink roller, and an appropriate amount of dry oil can be added to suppress the drying speed.

2. The discoloration of the ink on the printed page causes poor coloration. Due to the poor pigment performance of the ink, inferior organic pigments are used, or heterogeneous pigments are used in combination, so that a chemical reaction causes discoloration, and this ink is not suitable for color printing.

3, printing layout pale ink. If too much ink is added to the ink or the detackifier is added, and the water content of the plate is too large, the sensory quality of the printing plate graphic portion will be reduced, and the ink color of the printing product will be faded. In this regard, the ink should be re-adjusted, that is, adding some of the original ink to the thin ink, so that the concentration of the ink is increased; the moisture of the printing plate is reduced to improve the coloring power of the ink.

4, the back of the printed product is dirty. When the printed version of the printing ink is thick, or when the amount of the auxiliary agent is not properly adjusted, the drying speed of the ink is reduced, and the back surface becomes dirty, and a certain amount of desiccant and release agent can be added to the ink. To eliminate the back of the prints dirty phenomenon.

5, layout ink lacks gloss. Due to the poor texture of the varnish, the insufficient amount of varnish, and the excess water on the plate, the printing ink layer will lack luster. For color printing products, bright ink can be used for printing, or an appropriate amount of brightener can be added to the ink to increase the gloss of the printed ink layer.

8. Inadequate adhesion of the printing ink layer and poor adhesion of the printing ink layer can be classified into the following types: insufficient imprinting of the abrasion resistance; insufficient imprinting of the low light fastness; insufficient chemical resistance Imprinting is not strong.

1. Due to the overabsorption of the surface of the printed product, the excess binder in the printing ink layer penetrates into the capillary structure of the substrate, resulting in that the pigment in the printing ink layer does not have enough binder to consolidate the film and protect it, thus producing The phenomenon of discoloration of the imprinted powder has disappeared.

2, due to semi-finished products in the post-press processing, such as light machine, folder gluer, cover machine operation, due to the presence of friction, so that the printing ink printing ink layer appears fade phenomenon.

3, due to the printing ink layer is not fast, in the strong light or UV process environment, it is prone to fading.

4, due to the lack of chemical resistance of the printing ink layer and the color of the imprint or imprinting is not strong. When the printed product is in contact with the packaged acids, alkalis, salts, soaps, greases, alcohols and other chemicals, fading occurs easily.

9. How to deal with printing quality problems:

1. Always mix the ink inside the ink fountain and pay attention to increase the ink in the ink fountain.

Color inks are often composed of multiple color inks. Due to the different nature of pigments, binders, and fillers in different inks, it is inevitable that different substances in the ink will be precipitated and suspended. Once this state obviously exists, it will inevitably cause the variation of the ink color of the printed product. Therefore, the ink in the ink fountain should be frequently used in the printing process to prevent the ink from being precipitated and suspended to ensure that the ink color of the product before and after printing is consistent. In addition, due to the reduction of the amount of ink in the ink fountain, it is easy to make the gap between the ink fountain steel sheet and the transfer iron roller smaller, thereby reducing the ink output amount and making the ink color of the print product fade. In order to avoid this from happening, it is also necessary to pay attention to adding ink regularly during production so that a certain amount of ink is always maintained in the ink fountain. 2,2, the partial adjustment of the ink density in the horizontal position of the printed product

Due to different layouts of printed products, such as horizontal layout of a section of text, webbing, and lines, the amount of ink suction is relatively small, and the corresponding ink steel adjusting screw can be screwed in, so as to reduce appropriately. The amount of ink delivered to this site. If a certain position of the horizontal layout is based on the ground or the plate, the amount of ink is relatively large, the corresponding adjustment screw should be twisted outward to increase the amount of ink, so that the entire color of the ink remains uniform and the color difference of the printing is prevented. The emergence of the problem.

3, the full version of the ink shade adjustment

Ink fountain ink to increase or reduce the overall amount of delivery, there are two ways to adjust, one by adjusting the gap between the ink fountain roller and the transfer roller to achieve; second is to adjust the size of the rotating roller arc roller to achieve. In the case of a thin ink, it is not appropriate to adjust the gap between the steel sheet and the transfer roller too large, so as to avoid the problem of ink unevenness or color miscibility caused by ink leakage. When adjusting the amount of ink, the rotating arc of the transfer roller should be controlled within 1/2 of its adjustment range. This can allow the ink to be flexibly adjusted during the printing process to mutate and mutate to prevent ink from being printed. Inconsistent ink.

4, correct adjustment and use of good ink to prevent the production of color printing

The scientific and rational use of ink is an important part of ensuring the quality of printed ink. The ink of printed color products is too thick or too thin, which is not conducive to uniform ink and ink. In general, when the temperature is low, the ink appears thick, and its fluidity is poor, which easily causes poor transfer and uneven distribution. In this regard, according to the characteristics of Inking, an auxiliary agent should be used to appropriately dilute the ink and make it Maintains good fluidity and delivery to maintain uniform ink consistency. If the ink is too thin, the ink will fade. The adjustment of the ink fluidity should fully consider the characteristics of the printer's rotation speed and ink structure. If the printer is fast, the ink path is long, and the ink roller is large, the ink will tend to thin and fade due to the large friction coefficient. Therefore, the above situation should be fully taken into account when adjusting the ink, and the printability of the ink can be reasonably adjusted. In addition, when mixing inter and mixed color inks, it is best to avoid mixing with inks with large specific gravity so as to avoid "layering" (precipitation and suspension) of the ink on the ink fountain due to the difference in specific gravity during printing. Chromatic aberration.

5, a good operating process technology to prevent the production of color printing

When printing, if the operation and technical measures are not in place, frequent stoppages occur in the production process, which is very likely to cause printing and color difference. In order to avoid this situation, first of all, we must pay attention to the reasonable maintenance of the machine. We must always maintain the Feida parts and the air pump to maintain a good state of use of the mechanical parts, so that the air path is unobstructed, and the printed sheets are smooth; Depending on the thickness and size of the printed sheets, the feeders, air pumps, and parts related to the transport of paper should be adjusted to ensure the normal transport of printed sheets. Third, the printability of the whiteboard paper must be adjusted as necessary. Shake and knead and other processing operations, so that the cardboard to achieve the effect of transparent, to eliminate the adhesion and adhesion phenomenon, and to achieve a flat cardboard, in order to facilitate the smooth transport of paper, while better avoid empty sheets, suction Multiple sheets and skew failures occur; fourthly, the stacking paper operation technology should be shut down. If the paper stack is not smooth, measures should be taken to level the sheets so that there is no obvious difference in height between the sheets. Through these process and technical measures, the control is checked to ensure the continuity of the paper feeding, so as to prevent printing chromatic aberration caused by parking.

In summary, the quality of whiteboard printing is varied, there are a variety of undesirable factors, and there are several defects. As long as we carefully analyze and summarize the experience of the production process, we can not only better prevent the occurrence of printing quality problems, improve the printing quality of the products, but also effectively improve the production efficiency.

Source: China Ink Technology Network