Napkin printing has become very popular abroad. The application of napkins is not uncommon in foreign restaurants or hotels. The domestic market is also limited to use in foreign fast food restaurants such as McDonald's and KFC, and it is basically a simple monochrome pattern. With the more frequent exchanges between China and Western countries and the improvement of people's living standards, the application of napkins has also been popularized, which will promote the rapid development of napkin flexographic printing. Since napkin printing is still a new printing content, let's briefly talk about some issues to be paid attention to when printing napkins with flexographic printing. 1. Issues to be noted when choosing napkin materials In the napkin printing, the printability of the napkin material itself is one of the basic elements to ensure the smooth progress of the printing. The requirements for napkins are as follows: 1. The surface strength of the paper. The low surface strength of the paper is an important reason for the surface roughening and de-powdering of the paper due to the adhesion and pulling force of the ink during the printing process, and the poor printing quality. Therefore, napkins with relatively high surface strength are generally selected. However, the surface strength of napkins cannot be very high. In order to improve the printing quality, methods such as appropriately reducing the printing pressure and adjusting the viscosity of the ink can be used for printing. 2. Paper ink absorption. There are many pores between the fibers on the surface of the napkin, so it has a strong ability to absorb ink. In addition to a small part of the ink layer on the surface of the paper, which absorbs and dries the paper, most of them rely on the oxidative polymerization of the connecting material in the ink to dry. If the ink used for printing napkins is too absorbent, and the binder in the ink is absorbed by the paper, it will cause the ink film on the surface of the paper to pulverize, resulting in faults such as unbearable imprint, dull gloss, and penetration through the bottom. In view of the high ink absorption performance of napkins, appropriate printing inks should be appropriately allocated, such as appropriately increasing the viscosity of the ink, etc., and pay attention to the printing pressure and imprint time to ensure the improvement of printing quality. 3. The smoothness of the paper. Napkins are low-smoothness papers that have strong ink absorption and poor gloss after drying. According to this, in addition to choosing napkins with relatively good smoothness, we must also pay attention to the reasonable allocation of inks that meet the printability requirements. 4. The moisture content of the paper. Napkins are very absorbent, so during the storage and printing of napkins, care should be taken to control the appropriate moisture content. Napkins are very thin, soft, highly absorbent, have poor tensile strength, and are easy to stretch. Napkins have a high content of cotton or fibers, which are prone to bleed and have a lot of paper dust. Folded napkins are divided into single-layer and multi-layer, pay attention to the problem of layer separation. In addition, during printing, the ink may cause the surface material to expand. If the layers are not tightly bonded, it will also cause the material to wrinkle and cause waste. In all these cases, you must choose good quality napkin materials. [next] Second, the selection of printing inks should pay attention to In the napkin printing, not only the ink with good printing suitability should be formulated according to the characteristics of the napkin, but also the ink that fully meets the requirements of sanitation and environmental protection, because the napkin products directly contact the mouth, hands or eyes of people and food. Therefore, it is necessary to select inks that absolutely meet environmental protection and food hygiene standards. As far as napkin flexo printing is concerned, water-based inks are mainly used because they do not contain volatile solvents, are environmentally friendly, pollution-free, and have no odor. In addition, some ingredients are added to the formula of the water-based ink for printing napkins, which can effectively prevent the ink printed on the napkin from bleeding or dissolving when it comes into contact with water or strong alkaline substances. During the printing process, the viscosity, pH and other properties of the napkin printing ink must remain stable, and the drying performance is appropriate, which is consistent with the printing speed and post-press processing requirements. The ink has a certain viscosity is necessary to maintain its normal transmission and transfer. Because the flexo ink only fills the anilox roller mesh and transfers to the printing plate by its own fluidity and adhesion, if the viscosity of the ink is too low, it will cause light color, large dot expansion, and high-gloss dot deformation. Disadvantages such as uneven ink transfer; and the dots are easily deformed during imprinting, which makes the reproducibility of graphics and text worse. If the viscosity of the ink is too high, it will also affect the ink transfer performance of the anilox roller. It is difficult to fill the ink into the mesh hole, and it is difficult for the scraper to scrape off the ink on the mesh wall smoothly. In addition, it may cause paper shaving, de-powdering, or even peeling of the paper, uneven ink color, and sometimes the color is not printed deep, which is easy to cause dirty plates, paste plates, blisters, dryness and other disadvantages. The printing speed of napkin flexo printing machine can be as high as 700m / min or 10,000 sheets / min. During high-speed printing and high-speed folding, the stability of ink performance is very important. Improper viscosity of ink may cause paper to break; drying is too slow Can not meet the requirements of high-speed production; drying too fast will result in dirty plates. The normal range of the pH value in ink printing is 8.5 to 9.5. At this time, the printing performance of the water-based ink is better, and the printing quality is stable. The effect of pH on the printability of water-based inks is mainly reflected in the viscosity and drying properties of the ink. When the pH value is higher than 9.5, the viscosity of the ink is reduced, the drying speed is slower, and the water resistance is deteriorated; when the pH value is lower than 8.5, the viscosity of the ink will increase, and the ink is easy to dry, blocking the plate and the anilox roller On the top, it causes dirt on the layout, and bubbles are generated. The pH value of water-based ink is mainly maintained by ammonia compounds, so it is necessary to avoid the leakage of ammonia substances as much as possible. In addition, it is necessary to add stabilizer to the ink tank regularly and quantitatively during printing to keep various parameters stable. [next] 3. The selection and operation of printing equipment At present, napkin printing mainly uses a flexographic printing machine with a laminated or satellite structure. The whole machine includes unwinding, printing and in-line processing parts. From unwinding, through printing, folding, embossing, fragrance addition, counting to finished products, the whole The machining process is fully automatic. Napkin printing, generally higher speed. Take the napkin flexo printing machine produced by Omit as an example, the format is 500 ～ 2740mm, the printing speed can reach 600 ～ 700m / min; the printing unit can be configured up to 8 color groups; there are single paper path, double paper path and even 8 paper paths and other paper collection methods. In the printing process, due to the particularity of the napkin material, the control of printing tension is one of the key factors affecting the quality of the printing. Many high-end flexographic printing presses have adopted shaftless drive technology, and are equipped with digitally controlled multiple floating rollers and pinch rollers, which have greatly improved the tension control and registration control of the equipment. In the napkin flexo printing machine, the drying method of infrared, hot air or a combination of the two is mostly used, and it is equipped with a water-cooled roller scheme to achieve a better drying effect. The napkin material itself has a lot of paper wool and the surface strength is poor. It is easy to lose powder and lint during printing. It adheres to the printing plate and gradually accumulates, which will cause dirty and blocked plates. It must be shut down for cleaning. In response to this annoying problem, many manufacturers install a vacuum cleaner in the printing unit to solve it, or cooperate with a special squeegee to reduce the incidence of such problems. 4. Issues to be noted in post-press processing Post-order processing is an important part in the flexographic printing of napkins. Taking folding napkins as an example, the folding method is flexible and diverse, and the folding is very particular. It requires square sides and clear edges and corners. In this process, tension control is especially critical. Embossing is also an important part of napkin production. Embossing can improve the softness and hygroscopicity of napkins. At the same time, the uneven pattern of different patterns also adds a beautiful effect. There are many ways of embossing, such as point-to-point, steel-to-steel, steel-to-paper, steel-to-rubber, etc., and can also be divided into partial embossing and full embossing. Napkin printing represents a new and powerful profit growth space, and the development momentum has been paid attention to. Many napkin flexographic printing companies are full of confidence in the current and future napkin printing market, and the prospects are encouraging. 16 Pins Hydra Stamp,eye hydra derma stamp, eye derma stamp,16 micro needle stamp,hydra derma needling stamp,hydra meso needles stamp, golden skin needling stamp,gold micro hydra stamp, gold meso hydra stamp, eye meso derma stamp, eye serum applicator,eye aqua stamp, aqua hydra stamp 16 Pins Hydra Stamp,eye hydra derma stamp, eye derma stamp,16 micro needle stamp,hydra derma needling stamp,hydra meso needles stamp Guangzhou Vantee Electronic Technology Co., Ltd. , https://www.finerroller.com