Section 2 Metal Printing - 1

I. Overview (I) Overview of Metal Printing Metal printing is a type of practical printing, commonly known as sheet metal printing. It is a printing method using hard materials such as metal plates, metal moldings, and metal foils as substrates. The substrates for printing include tinplate and tin-free steel sheet (chemically treated steel plate TFS: Tin or Free Steel. ), zinc iron plate, black steel plate, aluminum plate, aluminum stamping container, and aluminum, white iron composite materials.
Metal printing is seldom the final product of printing, but is often part of various processing processes such as various containers, covers, building materials, household electrical appliances, furniture, nameplates, and various miscellaneous goods. These products are mostly to enrich people's Life is the main purpose. Therefore, in order to arouse the desire of consumers to buy, increase the value of the sale of goods, as a promotional tool, should be a novel binding design and beautiful printing, so that metal printing becomes even more important. Metal printed products should generally have the following characteristics:
1 colorful, rich layers, visual effects are good: metal printing materials such as tin plated steel, because the surface of tin plated layer, with a flash of color effects, and then through the background color printing, printing graphics is more vivid. For tin-free steel or other metal materials, special flash effects can also be reproduced after surface treatment and painting.
2 Printed materials have good processability and versatility of design; metal substrates have good mechanical properties and processing and forming properties. Metal packaging containers can realize novel and unique design, and produce various shaped cylinders, cans and boxes. Packing containers, etc., to achieve the purpose of beautifying commodities and improving the competitiveness of commodities;
3 Contribute to the realization of the use value of goods and artistic unification: The good performance of metal materials and the good abrasion resistance and durability of printing inks not only create conditions for the realization of unique design and exquisite printing, but also improve the quality of goods. Durability and maintainability can better reflect the unity of use value and artistry of goods.
Based on the above reasons, the printing of metal materials has been developed in recent times.
(B) Metal Printing Process Types and Features 1. Types of Printing Process Selection The printing mode of metal printing generally varies from substrate to substrate. However, no matter what kind of material is used, it belongs to hard material. Therefore, metal printing is mostly based on offset printing. That is, the graphic on the printing plate is first printed on the intermediate carrier (blanket roller) and then transferred to the substrate. On the indirect printing method. So far, offset printing mainly includes lithographic offset printing, horizontal offset printing, gravure offset printing, and letterpress offset printing (dry offset printing). In metal printing, Table 3-3 shows the types of substrates, printing methods, and major product examples.
Table 3-3 Substrate, Printing Method, Major Product Example
Building materials (interior, exterior, etc.), decorative panels (electrical products, furniture, etc.) Containers for cans, snacks, medicines, decorations, oils, paints, etc.
Dry batteries, covers, toys, signs, monitors, decorative plates (household appliances, kitchen supplies, etc.) Aluminum foil container Decorations Beverage containers Containers such as toothpaste, medicines, foods, etc. 2. Characteristics of the metal printing process Metal printing is similar to printing paper, but it is different from printed sheets. This is determined by its process characteristics. The similar aspect is that the metal printing is measured from the printing angle, and mostly belongs to the category of offset printing. There are many similarities in the overall process from photography, color separation, printing, and proofing to printing. However, after all, metal printing is a special printing process. So each similarly-looking process operates differently. The generalization of the characteristics of the metal printing process can be explained from the following five aspects.
(1) The substrate is sheet metal, not paper. Therefore, the basic characteristics of the metal plate should be an important consideration for the metal printing operation process. Just as printing should focus on the printability of the paper, this is also the standardization of the metal printing operation. , Data is an important part. The metal plate is a general term. Metal printing materials should be selected from different types of materials according to the different requirements of can forming. At present, the metal materials commonly used in various metal printing factories can be divided into three types, rigid, neutral, and soft, depending on the hardness of the surface. The aluminum alloy sheet is a soft metal sheet, the ordinary thin steel sheet is a neutral metal sheet, and the chrome-plated steel sheet is a hard metal sheet. During the metal printing operation, the adjustment of the metal printing press should be based on different hardness materials, and the adjustment of the roller pressure and the selection of a suitable lining material. The lining materials used in general hard metal plate prints are mainly soft linings, and soft and neutral metal plates are preferably lining neutral. In addition, the performance of the surface of the metal plate directly affects the appearance of the printed product and the value of the product. For example, tin-plated steel sheets, especially hot-dipped tin-plated steel sheets, have uneven thicknesses on the surface of the tin layer, and the rough surface or uneven thickness of the steel body may cause a series of troubles for the printing. The uneven thickness of the tin layer on the surface is the main reason for the color unevenness on the metal. At the same time, the thin tin part of the tin can easily rust, directly affect the service life, and the surface roughness makes the ink uneven. Also will not print ink. Therefore, it is difficult to imagine that the pattern will achieve the expected effect of proofing. The unevenness of the thickness of the basic body of the steel brings greater harm to the operation of the metal printing press, making the adjustment of the pressure of the machine inconceivable. The ink color of the printed product is very different. Therefore, when selecting a metal plate, it is necessary not only to meet the printing requirements of the metal printing machine but also to meet the specific process requirements of the can making. This will not only print elegant, beautiful prints, but also produce metal packaging that meets quality requirements.
(2) Information plays a decisive role in metal prints Metal printing is not the ultimate goal, but a beautification of metal packaging. The purpose is to make all kinds of metal containers, such as tin cans, cosmetic cans, various types of caps, toys and so on. Its shape under the background of printing effects, showing the richness and advanced level of metal prints. To make the picture on the metal plate colorful, it can not be separated from the special role of paint. The role of metal printing coatings summed up in the following two points:
1 Increase the adhesion between the metal and ink film layers. Experiments have shown that the ink is directly printed on the metal plate, the adhesion between the ink and the metal is poor, and the finger rubs off at a time, and the wear resistance and the firmness are very poor. A layer of primer is printed on the metal plate, and then the ink is very different. The wear resistance and firmness of the ink film are significantly improved, which lays a good foundation for can forming after printing. This is because after printing a layer of special properties on the metal plate, it not only produces a strong adhesion to the metal, but also enhances the affinity with the ink;
2 The ink film layer on the metal print has a good protection effect, at the same time increase the brightness of the pattern on the metal plate, and can not change color, can not afford paint in the can forming. For example, after the printing is completed, a layer of paint is applied on the printing surface, so that the ink film can be protected, and the metal print can be maintained in a colorful pattern. And maintain the gloss of the color in the following canning process. A good metal printed product can often play a decorative role in beautifying the family's cultural life.
(3) Dedicated inks with special properties Metals differ from paper in terms of quality, surface properties, and hardness. The fundamental difference is that the surface of the metal plate is smooth like a mirror, while the paper is porous, composed of cellulose. . Therefore, the biggest difference between the paper ink and the metal printing ink is that the printing ink must consider the penetration of paper fibers by some solvents or auxiliary materials during the manufacturing process. When the solvent or auxiliary material penetrates into the paper using the pore phenomenon of the fiber, the ink film layer is already dried (i.e., the surface is dried). The metal printing ink is directly printed on the surface of a smooth metal surface that has no absorption capability. Therefore, the drying of the metal printing ink mainly depends on the oxidation conjunctiva of the ink itself or the volatilization of the ink solvent. The second difference is that metal printing inks are suitable for the performance characteristics of metal printing presses. Metal presses have their own characteristics in terms of pressure, operating conditions, and drying conditions. In addition, the speed of the metal printing press is 500 sheets/h, while the maximum speed of the paper printing press is 16,000 sheets/h or more. These are issues that need to be taken into account when printing metallic inks.
From the above two differences, the production of metal printing inks must not be mixed with paper printing inks, otherwise it is prone to a series of ills. In addition, in the preparation of tin printing inks, it is also necessary to consider the requirements of metal plate printing after forming, such as the manufacture of food cans. After food cans are sealed, they need to be sterilized and sterilized in a high-pressure vessel. This requires the ink not to lose paint, leg color, and light in the cooking process. This is a must for metal printing ink production plants. Another example is the manufacture of a skin-friendly grease cartridge. Since the skin barrier grease consists of a mixture of oil and water, the metal printing ink must have good water resistance. Other inks, such as those used to make metal printing toys, must have good rub resistance and no toxicity.
(4) In the operation of the entire metal printing press, it is necessary to try to find the operation process matching with the metal material. When the metal printing is performed, firstly, consider carefully the feeding table. For different thicknesses of metal plates, different properties of the material to consider the best blowing nozzle blowing force and suction nozzle. Avoid the disadvantages of conveying the metal plate during the printing process. Because different metal plates have different weights, it is necessary to adjust the air volume of the blowing nozzle and the nozzle at any time, and it is always adjusted to the optimum state. In addition, during the printing process, the metal plates on the feeding table must be fed into the main unit one by one. The function of the nozzle and the blowing nozzle is not enough. Because the adsorption force between the superposed metal plates is large, it is difficult to separate them. If two horseshoe magnets are present at the feed, a gap can be created between the iron skins. This is to use the same magnetic field, the same principle of repulsion to separate the metal plates. At this point, with the blowing force of the blowing nozzle, the metal is smoothly conveyed. The adjustment of the roller pressure is the key to the operation of the machine. When adjusting the pressure of the roller, in addition to the thickness of the metal plate, proper pressure should be considered. The severity of stress has a great influence on metal prints. In a sense, the adjustment of the cylinder printing pressure of the metal printing press is even more careful and more difficult than the pressure adjustment of the paper printing press. The pressure is too light, the net points of the prints are imaginary, and the pressure is too heavy to distort the dots, resulting in distorted graphics. Among them plate cylinder and rubber cylinder