Metal packaging screen printing features and requirements

In recent years, with the development of China's economy, the market has become increasingly demanding for Packaging. For Metal Packaging, the screen printing process has become increasingly popular. Especially for metal packaging drum products, screen printing has become an important way for the industry to increase product quality, and it has been widely adopted in China.
The screen printing of metal packaging is a kind of special packaging printing. It is a screen printing method using hard materials unique to metal packaging products as substrates. The printing materials mainly include Tinplate (tin-plated steel sheet), chrome-plated steel sheet, Galvanized steel sheet, cold-rolled carbon steel sheet, hot-rolled carbon steel sheet, etc., there are special packaging materials such as aluminum, stainless steel and other materials.
Metal packaging screen printing is an integral part of the production process of metal packaging. It is a label for packaging contents and contains certain advertising and advertising ingredients. Therefore, in order to arouse the desire of consumers to purchase and increase the sales value of goods, as a sales promotion method, novel design of binding and exquisite printing should be carried out. Thus, the screen printing of metal packaging becomes more important.
First, the performance characteristics of screen printing metal packaging
1. Physical properties and characteristics of screen printed metal materials.
Metal packaging materials generally have good heat transfer, electrical conductivity, high mechanical strength, and are ideal materials for metal packaging. Because of its good ductility, it is easy to cut, punch, bend, stretch and other processing. What is more important is that metal packaging materials can withstand various forms of processing and can meet the decorative functions of various packaging.
2. Technical requirements for screen printing on metal materials.
1 Flatness: The metal sheet must not warp.
2 Surface roughness: The surface of the metal sheet should be free of mechanical scratches, scratches, bumps, rough stripes, and other surface roughness.
3 Cleanliness: The printed surface of metal packaging should be clean and free of oil, dust, water marks and other unclean phenomena.
3, printing adaptability requirements.
1 Metal packaging materials have good processability and diversity of design. Metal packaging materials have good mechanical properties and processing and forming properties. Metal packaging containers can realize novel and unique design and manufacture various special-shaped barrels, cans and boxes. Packaging containers, etc., to beautify goods to improve the competitiveness of goods for the purpose.
2 Colorful, rich layers, good visual effects Metal packaging such as tin plate, because the surface of tin plated layer, with a flash of color effects, and then through the background color printing, graphic printing is more vivid. For tin-free steel or other metal materials, special flash effects can be reproduced after screen printing by surface treatment and painting.
3 It is beneficial to realize the use value of goods and the good performance of artistic uniform metal packaging materials and the good abrasion resistance and durability of screen printing inks. It not only creates the conditions for the realization of unique modeling design and exquisite screen printing. The decoration of the packaging surface not only makes the packaging more beautiful, but also greatly enhances the value of the metal packaging itself, improves the durability and maintainability of the goods, and can better reflect the unity of the use value and artistic quality of the goods.
4 An important means of reducing costs The use of screen printing has changed or simplified the production process of certain metal packaging products (steel drums, etc.) and reduced production costs.
Due to the above reasons, the screen printing of metal packaging has been rapidly developed in recent years.
Second, metal packaging, screen printing design features and requirements 1, metal packaging, screen printing design features packaging is a concentrated expression of product features, but also the product's eye-catching face. A high-quality Packaging Can not only reflect the face of the era of science and technology, reflect the modern aesthetic, but also show the high-tech value of the product. Therefore, to improve the functional design, modeling design and decorative design of packaging, and to use appropriate technological means is the goal pursued by the packaging industry today.
At present, the use of screen printing methods to produce metal packaging graphics has become an important means, because screen printing has a unique performance, a variety of types of ink, ever-changing colors, are free to choose. Therefore, to improve the design and process level to create a new metal packaging screen printing. The specific approach is as follows:
(1) Modeling proportion: The proportion of graphic and graphic modeling of metal packaging products is closely related to the structure, overall shape and layout of the content products. With the development of the times and the change of aesthetics, the ratio of packaging modeling is also constantly increasing. Variety.
(2) Layout design: The design of each function of the metal packaging surface should be reasonable and provide consumers with the greatest convenience. The design of the pattern is implied by profound meaning, which represents both the nature of the product and the production unit. The pattern design should pay attention to the following factors: 1 It should have long-term use, and should not be changed frequently; 2 Concise and eye-catching, can leave a deep impression on people; 3 Has a unique and novel style; 4 Reflect the characteristics and nature of the product .
2. The design requirements for screen printing of metal packaging The most important thing for any job is the initial basic work. The design with screen printing as the main process, in addition to following the principles of economy and practicality, should also focus on the combination of science and craftsmanship. To ensure that the content is accurate and the layout is reasonable, appropriate decorative patterns are added, organically link the characteristics of screen printing with aesthetics and the optical color of the material, and become an important design concept for making packaging appearance with the screen printing process. .
(1) As the screen brush is not easy to express the effect of subtle lines, it is necessary to leave space or overlap at the adjacent or adjacent positions of the two colors. The width of the lines and the size of the handwriting also exceed the maximum resolution of the platemaking 0.1. Mm or more.
1 In the design of color printing, the outside frame size should be as large as possible to ensure that the size and shape of the inner frame are accurate, so as to ensure that the frame does not touch the inner frame when the screen is closed.
2 When the adjacent color areas do not require space, they must be designed separately, and two rows of lights should be used. These are two differently shaped color areas, and no gaps are required in the middle.
3 At the intersection of two color blocks, it is not easy to print very well. This situation can be compensated using overlapping design methods. The outer frame of the color frame is covered with a frame. This also needs to design the secondary emission separately. The surrounding area of ​​the patch area should be slightly larger than the drawing requirements. In other words, when two colors are adjacent to each other, the light area design will be larger and the printing will be darker. Light color to prevent gaps in the middle.
(2) If there are more appearance requirements, whether it is the use of multi-level overprinting or multiple color screen printing, it will make the layout appear cluttered, although colorful, but lost the sense of elegance and dignity. According to the principle of darkness in the dots, the neighboring parts of the complex area are printed in the same color in different sizes, different shapes, or different densities. As a design, a row of photos, a print, so reducing the multiple positioning, multiple printing troubles and improve efficiency. It can not only play the role of color zoning, but also make the layout of the layout in accordance with the aesthetic style of the times, and subtly blend functional beauty with artistic beauty. Packing and printing with a proper, comfortable, strong sense of the times. Fully shows the value of the product.
(3) Emphasize the decorative effect. For those printing surfaces that are simple in content and large in space, properly matched with different shapes of color blocks and dotted with decorative lines will make a few simple and boring contents vivid and lively.
(4) Select the appropriate font. Text design, Chinese, Pinyin, English, and numbers are common languages ​​for packaging designs. The design of texts not only needs to meet the needs of content functions, but also must have good craftsmanship and aesthetics. Most of the Chinese characters use Song-style, imitation idioms, and cymbals. Chinese Pinyin letters and English mostly use masculine, long, and other ligatures, and flat ligatures. Numbers are the most common symbols. The ratio of height and width directly affects the recognition effect. Height: Width is generally (5:3) ~ (3:2). Commonly used Song fonts, due to the square shape, the pen front is obvious, horizontal and vertical uneven, the font body is printed on the metal packaging below 4.2mm, will appear thin, the title of the print is also seemingly drifting; imitation of the characters in the horizontal and vertical thickness uniform, clear angle, Fine fonts, small print or title effects are very good. When the character body is above 4.8mm, the bold characters are often used. The characters are dignified, the strokes are thick, and the marks on the package are sturdy and eye-catching. When a large headline or space is large, a square typeface or a variant typeface can be used. The printed version is open, bold, and has a strong sense of calligraphy.
In short, the selection of characters should be consistent with the screen printing process characteristics. After printing, it should produce a stable, thin, easy to read, and easy to distinguish effect.
(5) Use standard symbols. Some product's nominal, commonly used English letters or all kinds of symbols, such as Kg, mm, L, Ω, φ, etc., for the sake of accuracy, we try to use standard symbols directly maps. The commonly used Chinese characters do not use handwriting. Instead, the words on the letter board are put into a positive film, and are pasted on the drawings, and then turned into negative and positive films to ensure the consistency of the entire font.
(6) Seriously treat each drawing, and on the premise of respecting the wishes of users, take the initiative to negotiate artistic re-creation with users, apply mature tactics and unified image to different products, and establish their own style.
(7) Take seriously the weak links in overprinting patterns. The level of craftsmanship is the technical basis for guaranteeing and representing the level of design. It is also the creation of the beauty of the product's texture, thereby enhancing the protection of formal beauty. Therefore, screen printing should also prevent rough fabrication and damage the appearance of the image. It is often found that different manufacturers print different products on the same film. There are technical differences, there are differences in color matching, material selection, and more is the difference in the quality of the process.
(8) According to the user-supplied design sketches, perform positive drawing, engraving or mapping, and then make a plate. Since the microcomputer has been used in the design of the system, the microcomputer design is used. The light drawing version is a relatively advanced technique, and the size of the design is also relatively accurate. If there is no advanced equipment, drawings, maps, engravings, etc. can also be used for less demanding products.
Third, the quality characteristics and requirements of metal packaging screen printing












Metal packaging screen printing, from the process, the printed pattern, lines must be clear, ink full, which is related to the choice of silk screen mesh number, Stretching tension, printing pressure, printing speed, ink viscosity and a series of printing data.
1, carefully select the screen according to the printed characters, lines determine the screen, generally use 300 ~ 350 mesh screen. Using a screen with more than 350 mesh, although a good printing effect can be obtained, due to the ink layer being too thin, the corrosion resistance of the diamond plate will not be strong in the subsequent processes. The selected wire mesh is tensioned under 8 tensions, and the glued net frame and the plastic surface are inversely stretched by being laid upside down on the stretched screen surface. The purpose is to stretch several small meshes at the same time and save the wire mesh. The frame can also be discharged at any angle, avoiding right-angle stretch nets and reducing the odds of jagging during printing.
2, stretch nets in the printing of general graphics, you can completely use hand-stitched network, both to save money, but also labor. For printing more complex or detailed graphics, the web tension first affects the printing accuracy, the tension is too small, and the consequences are almost all unclear. Therefore, mechanical or pneumatic stretch nets must be used. When stretching the net, the tension of the net must be gradually increased. The required tension cannot be pulled once. The mesh should be leveled evenly. When the tension is reached, it should be held for a few minutes before sticking to the web, and then glued. Stretch a good network is best to stand for 3 to 4 days, flat on the desktop or other places not easy to touch, until the tension can be used evenly.
3, screen degreasing treatment with flowing water wet screen, with detergent or detergent coated on both sides of the screen, scrub with a brush, both to achieve the purpose of de-referring, but also coarse wire mesh. Alkaline detergent on the Internet must be washed under running water, otherwise it will affect the quality of the plate.
4. Drying Place the washed wire mesh in a dry and ventilated place or dry it in an oven. The drying degree should not be too high, so as not to affect the screen deformation.
5, plate-making due to screen printing requirements of the pattern, the characters are clear. Full ink, which requires the production of high-quality screen. First of all, two situations should be excluded: The first is that the photosensitive film is too thin, the printed pattern, lines are not only unclear, but also serrated, line sprinkled, rounded corners blunt; the second is the photosensitive film is too thick, despite printing When a lot of pressure was added, the ink layer was still very thin and the lines were severely broken and could not withstand the corrosion of potions. Therefore, the thickness of the photosensitive film on the 350-mesh screen is preferably ideal for the 224-squeegee method. Among them, the speed of squeegee and the inclination of the squeegee are also major factors affecting the film thickness. Squeegee speed can not be fast, slowly move the scraper, not only can eliminate the bubbles in the glue, but also to obtain a uniform photosensitive layer, scraper back and the angle between the screen is 25 °, when the scraping force both hands to be uniform.
It is worth mentioning that the precision of the printing process using photo-sensitive adhesive plates is not as high as that of the capillary film, but the film resistance of the film is not as good as that of the photo-resist. Therefore, a polyester film is applied on the non-printing surface immediately after the application of the photoresist, and scraping is performed twice with a scraper to drive off the air bubbles to prevent the occurrence of pinholes; then it is placed in an oven and dried at a low temperature, and the temperature is controlled at 40°C. Inside; After drying, remove the screen to remove the polyester film, and then dry it for 1 to 2 minutes to expose. This method of "changing" a film film with a photosensitive adhesive can improve screen printing accuracy.
6, the exposure of the majority of the sun exposure. According to the photosensitizer content exposure 30 ~ 45 seconds, the exposure should be repaired before the film, dust and stains. If the screen is facing up and the frame is down, a black or blue carbon paper should be placed between the pad and the screen to prevent the light from refracting, resulting in unclear patterns or difficult to develop.
7, the development of the exposure should be immediately put into the development, with 30 °C warm water soaked screen 1 ~ 2 minutes until the unexposed film was swollen with tap water until the pattern is clear.
8, dry with a sponge to remove excess moisture, placed in ventilated sunlight to dry naturally or in a drying oven at 40 °C.
9. Revised version and proofreading of nets and negatives, closed mesh outside the pattern and drying, can be delivered to the printing process.
10. Printing adopts self-drying corrosion-resistant printing ink, keeping the distance between the screen plate and the surface of the metal package from 3 to 4 mm; the blade is required to be sharp, straight, and not to be nicked, and the ink is scraped from front to back. Scraper tilted 45 ° angle, parallel, not too fast to scrape ink. Try printing about 10 times, if the amount of ink is normal, the pattern is clear, you can print in batches. In order to reduce the workload of the patched version, it is best to check the print quality every time it is printed 10 times in order to correct it in time. Due to the dryness of the environment and the serious dust, white spots and lines appear on the printing plate, which is mainly caused by dust sticking on the web and particles in the ink. Apply an appropriate amount of thinner to the dirt. After printing, the screen should be cleaned in time. Propionic acid cleaning fluid is generally preferred. When the skin is stimulated, the ink sticking to the web is easy to wash. Cleaned screens should be packaged in a timely manner and properly placed for reuse.
11. Inspection of printed parts The printed parts cannot be directly corroded. After the ink is completely dry, the defects in the printing are carefully and overhauled; the parts to be filled are repaired with a plate-making glue, and the characters are unclear. Modify; to do self-examination, mutual investigation, special investigation, minimal control of print quality deficiencies, and then can only be transferred to the next process.
12, rational selection of ink multi-color layered overprint, to wait until the previous color can not afford to stick to the next color printing, once the color is printed and damaged, do not wipe the background dirty. In order to ensure the finished product rate and reduce the difficulty of repairing, the type of ink and the diluent are selected.
When the metal package surface color is light, UV ink can be used to add resin ink color to ensure uniform color. After the printing is cured with ultraviolet light, the color ink particles will be firmly embedded due to the curing of the UV ink, the surface will not stick, and the color will be printed immediately. The next color ink can use thermosetting metal ink, after printing heat curing. Not only can you get the ideal combination of strength and hardness, but you can also get an unexpected pearl-like background color, and the general solvent will not be rubbed off, so it is easy to repair.
13. Pre-printing scheme and printing sequence should be tested with a piece of sticky copperplate paper. Check if there is any lack of graphics, if the scraping edge is straight, whether the net distance is appropriate, and whether the ink is even, try 2~3. Times, after the network to eat ink evenly after the official printing. When printing, continuous graphics can be scraped and printed with a large scraper. For separate graphics, small scrapers of various sizes can be used for partial printing. All the nets are printed after finishing printing. A small area is easy to obtain a flat surface. The fullness of the printed text will not appear in different shades.
14. The cleaning of the screen is very important. Some residual ink in the picture and text, especially the repetitive use of the reticulated frame, can cause a barrier mask, and the degree of reproduction of the picture and text is affected, that is, the printing defect. Use the following methods to clean the screen.
(1) Wipe the net with the ink cleaning agent, the ink is clean but the taste is large.
(2) Wipe the net with banana water, taste small, large amount of cotton yarn.
(3) Wipe the web with cotton and rubbing the ink. The ink leaves the web in a stripped state and is then wiped with an ink cleaner. This method is convenient and efficient.
In short, from the design to the film production, from screen preparation to screen printing, from ink selection to printing, the best possible process conditions are selected for each link.