Corrugated cardboard printing color consistency and layout accuracy (on)

With the development and popularization of flexographic printing technology in China, water-based flexographic printing technology has basically been adopted in domestic corrugated box printing.

The flexible version is flexible and flexible. It can compensate for the thickness error and flatness of the corrugated cardboard in the printing process by using its own elastic deformation to make the ink layer even and obtain high-quality printing. The flexographic printing can be printed in the field. Can also be screen printing, can complete the multicolor screen printing; its use of environmentally friendly water-based ink, no pollution to the environment, does not corrode plates, ink absorption, fast drying; flexographic printing belongs to light pressure printing, The corrugated height will not produce excessive pressure, and the ink of the prints will be soft and uniform. The structure of the flexographic printing press is simple, and the loading, adjustment, cleaning and maintenance are very convenient. These are the advantages of the flexographic printing technology. It can be said that the corrugated board is flexible. Printing technology is a high-efficiency, high-quality, high-speed printing method.

However, the corrugated box flexographic printing started relatively late in the country and the printing technology level has yet to be improved. The following discusses how to maintain the consistent color printing and corrugation accuracy of corrugated board inks.

Printing color

The following factors affect the consistency of printing color:

Water-based ink quality

The printing color is formed by the color of the ink. Therefore, the quality of the water-based ink is related to whether the color of the carton printing is pure or not. It is the key to bright colors and directly influences the consistency of the printing color. Therefore, special attention must be paid when selecting the printing ink. Whether it is direct purchase of finished ink or self-made ink, the technical indicators of ink and wash must be strictly controlled. There is no obvious difference between high-quality ink and color mark, and the touch is delicate, sticky, and the concentration is suitable; water or alcohol solvent is used to dilute without precipitation and agglomeration phenomenon; no foam is generated by stirring with a wooden stick; the affinity for color mixing with other inks is good, and all Miscible phenomenon, the ink color is pure, no abnormal reaction. The technical parameters of ink and wash are:

The color should be similar to the standard template color. The sample can be compared with the standard color development wheel, and it should have stability and consistency. This can maintain a certain printing color in different batches of printing. Save the qualified sample box when the carton is proofed, which is used for the inspection reference comparison in the future production. The replacement of the sample box of the sealed sample must be consistent and can be replaced after the comparison and approval. One use of the ink should be guaranteed when printing each batch of cartons. It is best to print batches at one time when printing, otherwise, the same barrel of ink is used, and color differences also occur. The reason is that the original ink plus water or alcohol solvent is not sealed after being diluted and exposed to the air for a long time. The chemical components in the ink react with the oxygen in the air, that is, the pigment is reduced. At the same time, the light also has a decomposition effect on the ink.

Viscosity Ink viscosity is generally controlled at 20±5 seconds, which varies depending on factors such as printing speed, type of anilox roller, and ink transfer method. The viscosity of the ink determines the transfer properties of the ink, the firmness of the print, and the gloss of the color. Therefore, to ensure the consistency of the printed color, the viscosity of the ink must be controlled within a certain range. In the actual production environment temperature and other factors will have a certain impact on the ink, and with the volatilization of the ink solvent, its viscosity will gradually increase, in order to maintain the stability of the ink viscosity can be properly added to the ink stabilizer, you can also add traces of timely Water is adjusted. When printing the field version and the cable version, the ink viscosity should be different. In general, when printing on the cable version, the viscosity is slightly lower; the printing speed is different at different times. When the printing speed is high, the ink viscosity is lower, and when the speed is slow, the viscosity is higher. Moreover, the effect of temperature on the viscosity of the ink, especially in winter, should be taken into consideration during actual production as well as during storage in the workshop.

Dryness The drying speed of water-based inks affects the printing speed and requires the ink to dry faster. It affects the printing speed, and the color shift of the printing color may occur due to the difference in ink dryness during pattern overprinting. Therefore, according to the different products or substrates, the ink drying time should be properly adjusted. To ensure the ink drying is good, we must also consider the appropriate viscosity and PH stability.

Steady ink transfer

The viscosity of the water-based ink, the type of anilox roller of the printing press, the ink transfer method, and the printing speed are related to the ink transfer state. Make sure that the anilox roll is clean and free from wear. Therefore, maintaining a balanced and stable operation speed of the printing press can not be ignored. This not only ensures that the printing press has a stable ink transfer state, but also plays an important role in ensuring the consistency of the printing ink color. The speed of operation has a certain relationship with the amount of ink to be transferred, the operation speed is slow, the amount of ink transferred is large, the operation speed is fast, the amount of ink is small, and the stable operation speed can obtain a stable ink transfer amount. Because the viscosity of the water-based ink has a certain positive relationship with the ink transfer amount, a large-area field printing can use a slightly slower running speed, a slightly higher viscosity aqueous ink, and a low number of anilox rollers. The dot printing requires a faster running speed and a lower concentration of aqueous ink and a higher number of anilox rollers. In general, the higher the number of anilox roller lines, the smaller the amount of ink transferred, and the lower the number of lines, the greater the amount of ink transferred. In actual operation, the slower the printing speed is, the larger the ink transfer amount is, and the larger the viscosity is, the greater the ink transfer amount is. It can be seen that when performing on-the-spot printing or block printing, an ailox roller with a smaller number of lines can be considered, ink with a larger viscosity can be used, and a slightly slower printing speed can be combined. On the contrary, in the case of high-line and color-graded printing, higher-line anilox rolls can be used, inks with lower viscosity can be used, and faster printing speeds can be used, which of course can be used in combination with actual conditions.

(to be continued)