High-grade napkin printing process

The author went to Germany in 2003 to visit the "Drubba" printing machinery exhibition in Düsseldorf every four years, and came into contact with the napkin folding printing machine. At the same time, after visiting Germany, I also visited several cities in Italy. During the ten days abroad, I paid attention to the napkins used for three meals a day, and paid attention to the collection of each meal. I wanted to see the consumption concept of Europeans. Will gradually affect the Chinese. Once China ’s 1.3 billion population changes its table culture, the use of napkins will bring huge business opportunities.

After returning to China, I began to pay attention to the production and use of domestic napkins. I found that facial tissue handkerchiefs had simple color-printed products. I was also lucky to see the largest domestic napkin manufacturer in Wuhan Green World. The founder of the company, Mr. Su Xiaohai, led us to visit the Italian OMT company. Production of facial tissues for napkin printing machines. I also saw the domestic four-color napkin printing machine. In Jiangsu, Zhejiang, Fujian, and Guangdong, we did a lot of research and found that most of the domestically produced napkins are sold overseas. The domestic products are only low-end products, and the scope of use is also limited to facial tissues. . Due to the large gap between the material structure and the European and American samples I collected.

Facial tissue is a simple combination of two or three layers of wrinkle-free toilet paper, printed with flexographic ink and then embossed by a toothed roller and paper foil roller. This product can only be used as a handkerchief in Europe. This kind of product is rarely used as a cushion on the dining table. In the napkin samples I collected on the European and American dining tables, I found that the materials were micro-sizing compounded before printing. Such napkins are smooth, wrinkle-free, and have a texture and a heavy sense. A special product is a three-layer structure with a printed layer in the middle. The micro-plastic composite product has texture and good flexibility, and the product surface is more beautiful. Some printed materials are not toilet paper but non-woven fabrics. After detailed comparison, we believe that the current domestic products are only facial tissues, not napkins used abroad.

If the napkins used on the dining table are to be produced in China at present, it is necessary to change the method of embossing and pressing into micro-sizing and then printing, so as to make a qualitative leap in the quality of napkins.

Regardless of the facial tissues or pad napkins used on the dining table, the printing adopts the flexographic four-color or five-color printing and folding method, but the printing quality of domestic napkins and facial tissues is affected by the materials, and the product quality is still similar to that of foreign products. Large gap. The reason is that China's current consumption is still at a relatively low level compared with Europe and the United States. It is impossible for domestic base paper manufacturers to use 100% wood pulp for production. At the same time, in order to reduce costs, the amount of wet strength agent added is small, which makes our country The raw paper and foreign raw paper can not meet the printing requirements on the surface smoothness and wet strength.

Flexo printing is a method of ink printing. After the paper surface encounters water, especially when the amount of ink is large, it is more likely to cause swelling of the paper. After printing, local unevenness affects the next printing, and it is also easy to cause wrinkles. At the same time, the swollen printing material is exacerbated The fluctuation of tension makes the accuracy of overprinting fluctuate greatly. It is difficult to produce a good product. Due to the poor wet strength of toilet paper, it is easy to bring loose fibers from the paper to the plate surface after contact with the printing plate, resulting in paste printing that prevents continuous printing and more seriously affects the printing quality and yield .

At present, domestic imported equipment and domestic equipment are basically four-color continuous printing and then unified drying and embossing folding process, so it is difficult to ensure product quality.

In response to various comparative studies, Xi'an Heiniu Machinery Co., Ltd. has developed a CRY460 napkin printing machine suitable for China's national conditions, which basically solves many problems in the printing process.

Napkin printing materials are very flexible and cannot be unwound. Both domestic and foreign equipment use a belt surface to drive unwinding. In order to ensure the accuracy of printing registration and folding under normal tension, to adapt to changes in different materials and ink volume, in its All levels are adjusted to a certain percentage of the drawing rate. Pure mechanically adjusted belt unwinding will produce proportional fluctuations and cumulative errors, resulting in poor registration accuracy and difficulty in printing. The unwinding of the CRY460 napkin printing machine manually adjusts the unwinding of the mechanical transmission, changing the design to AC servo driven unwinding, using a low-friction cylinder to finely detect the tension, and closing the loop to control the speed difference. This firstly provides a reliable guarantee for prepress tension control . After long-term operation, the registration accuracy is ≤ ± 0.5mm; the folding accuracy is ≤ ± 1mm; stable and continuous production is achieved.

The CRY460 napkin printing machine changed the traditional method of four-color centralized drying after printing. An oven was added to each color group, so that the swelling after the ink on the napkin was removed after each color printing was completed without affecting the next color group. This guarantees The smooth and wrinkle-free printing greatly improves the printing quality, and the ink transfer amount of each color group is more stable and accurate, and the service life is long. The steel gravure ink transfer method is eliminated, and the ceramic transfer roller with more precise and accurate ink transfer is used. Screen printing provides a guarantee.

CRY460 is specially designed to add a micro-coating device after unwinding. The device can coat the anti-fouling solvent on the surface of the printing substrate in a small amount while rolling, so that the small loose fibers on the raw material will not stick Paste on the printing plate, which greatly improves the printing duration, reduces the number of times to clean the plate, improves the life of the printing plate, and improves the yield.

According to the characteristics of the Italian OMT folding mechanism and the domestic folding mechanism, a new type of folding mechanism has been carefully designed to significantly improve the folding speed and accuracy.

Xi'an Heiniu Machinery Co., Ltd. has started researching on toilet paper micro-sizing composite equipment. The printed materials with a small amount of sizing compound are flat and wrinkle-free and increase the sense of cotton. The products after fine printing can be compared with European and American products. . We are willing to sincerely cooperate with colleagues in the industry to conduct technical discussions and exchanges, so that the napkin printing field can quickly catch up with foreign standards

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