How to improve the printing quality of aluminized paper labels

First, the use of "dark ink thin or second printing" printing process

The surface of the aluminized paper is non-absorbent. After the ink is printed, it is mainly dried by oxidation polymerization. In this type of dry ink, once the ink layer is printed thick, it is not easy to achieve complete drying inside and outside the ink layer. This will not only affect the normal overprint, but also cause the problem of sticky quality problems. In order to avoid this problem, when printing spot color inks, the hue of the ink should be appropriately deepened to make the printing ink layer thinner. This will not only meet the requirements of the hue of original printing, but also facilitate the rapid completion of overprinting. , And better prevent the printed product from appearing dirty.

For printing on-site full-size aluminized paper, a “secondary printing” method may also be adopted. First, the ink is thinly printed once and then overprinted once. This facilitates the rapid drying of the ink layer and better prevents the occurrence of printed products. Viscous dirty phenomenon.

Second, the anti-sticking process control technology

After the aluminized paper is printed, the ink layer is suspended on the surface of the aluminum film and will not dry quickly. If the process is not well controlled, it is easy to appear dirty and affect the product's print quality.

The printing anti-sticking control mainly includes the following: fine and uniform high-quality dusting; dusting and printing of semi-finished products; avoiding the use of super-high-speed printing; and the speed of printing aluminizing paper labels to control the speed of 3000 sheets/hour. In the range of 5000 sheets/hour, the semi-finished products stacked on-line by the printing machine should be stacked and separated by partitions. The height of the semi-finished products stacked on each partition should not exceed 5 cm; the ink layer of the printed product can be printed on half when it is semi-dry. The paper stack is loosely turned to allow the oxygen to enter the printing paper stack to promote the oxidative drying of the ink layer of the printing product; the printing ink should be kept in a relatively small amount as much as possible to maintain the relative balance of the ink and the fountain solution. Through the technical control of these processes, it is possible to better prevent the stickiness of printed products.

Third, the correct choice of aluminized paper ink varieties

Aluminized paper is a non-absorbent substrate, and the type of printing ink it uses should also be matched to its characteristics in order to achieve normal printing and ensure print quality. Due to a variety of oxidized conjunctiva drying inks, there are certain differences in the type, fineness, content, dispersity, and binder of the pigments used, resulting in the hue, concentration, viscosity, vividness, adhesion, and drying of the ink. And so on, so the printing of aluminized paper trademarks should be based on the characteristics of the product, the characteristics of the printer, the printing environment and other factors to consider, select the right type of ink for printing, in order to ensure the stability of the product printing quality. Therefore, the procurement of aluminized paper printing ink, should choose a manufacturer with a certain production scale, its quality is relatively stable and reliable, it is best to confirm the use of a manufacturer's ink. The current aluminized paper printing inks mainly include: SF ink produced by Shenzhen Ink Company, TSP ink produced by Tianjin Toyo Ink Company, JP ink produced by Hangzhou Hanghua Ink Company, and AS ink produced by Shanghai Riken Ink Company.

IV. Reasonable Arrangement of Color Printing Order of Aluminized Paper

The rational arrangement of the printing color sequence of the aluminized paper is conducive to improving the overlay accuracy and the color rendering effect of the aluminized paper product. From the point of view of registering, it is preferable to print a color plate with no accurate overprinting profile first, so that the printed sheet adapts to the environment, and after the water content of the paper is relatively balanced and stable, the color plate with higher precision of overprinting is printed in order. Overprinting of the product's layout has both dot and field sections. To make this kind of product dot printing clear, the ink on the ground is thick and colorful, and it is conducive to the accuracy of overprinting. It is usually necessary to print an anilox version first and then print it on the ground. Version. From the viewpoint of preventing ink from being scratched or stained, it is advisable to print the area with a small ink-receiving area, and print the area with a large amount of ink on the back.

It is clear from the process practice that the large-area layout is printed on the back, which not only improves product registration but also improves labor efficiency. This is because if a large-area layout is printed first, the printed sheets are prone to curls, elongation and other undesirable phenomena. Once the printed sheet is curled, it will affect the normal feeding and positioning. In this way, when the second set and the overprinting, it is often necessary to knock the sheet on the paper to increase the stiffness and flatness, and then to achieve a smooth loss. Paper and positioning. This type of printing sequence has a low accuracy of overprinting, and when it is knocked on paper, it is laborious and laborious. I have seen such a situation: there is a packaging printing company in the past printed aluminum paper trademark products, has been accustomed to use the first printing large layout, after printing small layout. "Formatting" printing process operating procedures, the results of the deformation of the print sheet is severe, some parts of the layout of the outline overprint error of up to 0.5mm ~ 1mm range, the number of waste products is very alarming. Later, the printing color sequence was changed to a small printing area first and a large printing area after printing; the printing area with a lower printing accuracy was printed first, and then the printing was overprinted with a high-precision layout, so that the overprint quality of the product was greatly improved. The consumption has dropped significantly. Therefore, when overprinting and overlaying, as long as the color rendering effect is not affected, it is best to arrange a small layout first and a large layout afterwards.

Fifth, the correct control of printing ink and fountain solution

In order to ensure the stability of the ink quality of the printed product, the printer drum is required to use a small lining of the deformation coefficient to ensure that the packing lining during the printing process does not have obvious compression and deformation; the precision of the machine's imprint and its associated components is higher, so that the printing pressure Always keep constant; printer's rubber roller, water roller shaft head, bearing accuracy is high, the roller body should not be eccentric, in order to ensure the stability of the ink before and after the printing process. In the aspect of inspection and control, because of the high reflectivity of the aluminum layer on the surface of the aluminized paper, it is easy to affect the accurate discrimination of the color by the naked eye. In addition, the eye color is easily affected by differences in vision, light source characteristics and angles, and environmental and psychological factors, resulting in errors in color discrimination. Therefore, in the process of printing aluminum-plated paper, it is not sufficient to control the printing ink color according to the customary production method, according to proofs or proofs. With the help of advanced optical instruments, the use of spectrodensitometers and other tests to carry out a serious inspection of printed products is a reliable measure to accurately control the ink color of printed products.

Non-absorbent aluminum-plated paper consumes relatively little water, and the fountain solution has a small controllable range. It is suitable for fountain solution that uses alcohol and water. In the process of printing aluminized paper, it is easy to cause poor drying due to excessive emulsification. This requires that the amount of emulsification must be strictly controlled during printing, and the amount of fountain solution should be minimized to maintain the balance of ink and ink. Therefore, the concentration and pH of the alcohol fountain solution should be detected in a timely manner in production, and necessary supplements and adjustments should be made. in. When printing, depending on the climate, the pH of the fountain solution can generally be controlled between 5 and 6. The alcohol concentration can be controlled between 10% and 20%. In addition, it should be noted that: the dampening fluid with a tune should be prepared using tap water stored every other day to reduce the influence of tap water acidity on the pH of the fountain solution.

Reprinted from: China Ink Technology Network