Attention should be paid to the printing of vacuum aluminum-plated paper
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1. Prepress design
Due to the poor wear resistance of the vacuum aluminum-plated printing products, the gloss is not high, the materials are easy to break, the crease lines are easy to appear white and other practical problems, which will directly lead to poor molding of the product, the material stiffness is not good, and the printing ink will be subtle. Cracks and other issues. Therefore, in addition to the selection of high-quality aluminum-plated paper, in the design of the printing process, the characteristics of the aluminum-plated paper should be utilized as much as possible to avoid weaknesses. For the design of printed graphics, the pattern text should avoid the use of large-area opaque ink as the background color, and use the exposed bottom effect to highlight the unique metallic luster of the aluminum-plated paper. For offset dot images, the area is small, avoiding large-area four-color overprinting, and using spot color printing to improve color saturation. The color chosen should be as large as possible to highlight the metallic color tendency and gloss of the aluminized paper, and to use less contrasting spot colors. Select the ink should also use the transparency to print. Pay attention to the metallic color of the aluminized paper to the color rendering effect of the ink. Different cardboard background colors will have different color effects. If the transparent layer is printed on the aluminum layer, it may be golden yellow. Small texts and lines should avoid overprinting, so as to avoid the bottom or wrong color, increase the difficulty of overprinting, and increase the rejection rate. Try not to print large-area spot colors at the crease line to prevent the appearance of white or crease lines and to compensate for the lack of material folding. Learn more about the printing performance of aluminized paper, the post-press processing technology and the requirements of the customer's packaging process, fully consider the printing speciality of aluminized paper, and use the extreme color matching.
2. Selection of ink
Vacuum aluminum-plated paper is suitable for UV ink printing. It can be used for offset printing, screen printing, gravure printing, etc., but different printing methods have different ink requirements. The ten vacuum aluminum-plated paper is not resistant to friction. Therefore, it is necessary to pay attention to minimizing the number of overprinting during the printing process, and the speed of the vehicle should not be too fast. The process recipe of the aluminized material can be adjusted according to the specific conditions, and the paper is hard to crack when it is hard. When the paper is soft, it is not wear-resistant; the viscosity of the general ink should be lowered to avoid affecting the composite effect of the product. In the selection of inks, attention should be paid to the matching of inks and printing materials. The surface coating of aluminized paper is suitable for water-based coatings; the water content of aluminum-plated papers is preferably controlled at 5% to 6%. For the problem of cracking of vacuum aluminized paper, this usually occurs one or two months after printing or even packaging. In order to avoid this, it is generally necessary to do a printing test, and to test it by placing it for a while. The stability of the material is to be mass-produced after the material is qualified.
(1) Offset printing and screen printing. The aluminum layer of vacuum aluminum-plated paper has poor ink adsorption, especially in the process of offset printing, the process of penetration, polymerization, oxidation, conjunctiva and drying of the ink on the vacuum aluminum-plated paper takes a long time. Due to poor adhesion, sometimes the ink breaks at the fold, UV offset ink can try POP ink, and also pay attention to the viscosity of the ink. Offset printing and screen printing should determine the starting speed according to the drying speed of the ink. The moisture control of the offset printing is based on the non-dirty version. Many vacuum aluminum-plated paper manufacturers often apply back water for the purpose of final drying, but do not return water before they are supplied to the printing company, making the aluminized paper easy to curl during the printing process. The surface of the aluminized paper itself has a certain number of tiny holes, and moisture can penetrate into the paper, showing the importance of moisture control. Aluminized paper printing should pay special attention to the adhesion fastness and explosion color of the ink. There are two main reasons for the adhesion fastness of the ink. One is that the ink printed in the printing removes the ink printed first; the second is after printing. The ink layer on the surface of the paper is not strong enough to be pulled off. The solution is to increase the UV curing strength of the color ray or use wet humidification overprinting to complete the curing process at the delivery site; the latter is to use high toughness UV curing ink and add special varnish to the ink. Adjust its viscosity. As for the problem of explosion color, the general solutions are as follows: one is to perform water-based varnishing before UV printing; the other is to use two color-blocking overprints to increase the thickness of the ink layer to increase the folding resistance; Ink.
In the process of offset printing and screen printing vacuum aluminizing materials, due to the poor adhesion of UV offset ink to paper surface, there is sometimes a phenomenon of ink breakage at the fold, pay attention to its ink adhesion, and also pay attention to the consistency of the ink. . Offset printing and screen printing should determine the starting speed according to the drying speed of the ink. The moisture control of the offset printing is based on the non-dirty version. Because the surface of vacuum aluminized paper is not like composite aluminum foil paper and PET paper, it has certain fine pores, moisture can penetrate into the paper, so the control of moisture is very important; 3 the stacking of vacuum aluminum-plated paper can not be too much The maximum amount of cardboard should not exceed 3,000 sheets, because the surface of vacuum aluminized paper is not wear-resistant, too much stacking will crush the printing surface; 4 Note that the storage time of vacuum aluminum-plated paper should not be too long, it is best not to exceed two months, because After a long time, the surface will adhere to the back of the paper, causing the paper surface to bloom; 5 The printing of vacuum aluminum-plated paper should pay attention to the temperature when the heat curing is not too high, and the high temperature will affect the surface of the vacuum aluminum-plated paper, making it change. And too hot paper shrinks too much deformation, which has a great impact on post processing.
(2) Gravure. From the point of view of the suitability of aluminized paper and gravure, the current requirements for inks are mainly focused on solving the adhesion and explosion of the ink. In order to have good adhesion between the aluminized paper and the gravure ink, the medium between the two - varnish is the key, it can not corrode the plating layer, but also has a good affinity, but also does not affect the subsequent printing Leveling. Some insiders pointed out that the use of a 300-mesh anilox roll on aluminized paper, and then apply a uniform water-based varnish, so that the surface tension of the paper is increased to 38 dyne or more, the expected effect can be achieved, and the problem of gravure ink adhesion is initially solved. . Once the aluminum-plated paper is improperly controlled, it is easy to explode, which is related to the paper itself, PET film, glue, ink, temperature control operation and other factors. In the case of inks, the binder of the ink consists of a resin and a solvent. The resin has the ability to contain and release pigments, and the solvent acts to disperse and dissolve. Resin and solvent types and ratios can determine various properties such as ink transferability, dryness, and ink layer fastness. Generally, the gravure ink is composed of two or three kinds of resins and two or three kinds of corresponding auxiliary agents, and a mixed solvent.
In the use of ink, according to the characteristics of aluminized paper, increase the proportion of the flexible resin in the ink and the corresponding solvent, and pay attention to control the fineness of the pigment particles in the ink (generally controlled at 3 microns to 8 microns). If the pigment is in the form of a sheet, the color paste can be subjected to a rapid sanding treatment, and the soft particles which are difficult to be filtered in the primary color paste are refined, and the flexibility is optimized without changing the characteristics of high transparency and high gloss. You can get the desired results. In addition, care should be taken to adjust the viscosity of the ink to improve the bonding strength and anti-explosion ability of the resin and pigment. The color tone, saturation and transparency of the ink have a great effect on the coloration effect of the aluminized paper. The ordinary 3 to 4 times of sanding pigment can reduce the fineness, but it is easy to make the pigment color in the ink black and dark. And there is a rough phenomenon. To solve this problem, it is recommended to use pigmented color chips (ie, ink chips, such as Zhuhai Fangdia Ink Co., Ltd.), which uses a special production process to paint the pigment itself. The color of the light is played to the best. The mirror-like light transmission effect is also an important factor to ensure a metallic luster on pure aluminum foil and aluminized paper products. It not only affects the unique effects of aluminized laser paper, but also makes the ink transfer smoothly to meet the needs of overprinting, stacking flexibility, friction resistance, heat resistance, and post-processing.