The influence of the hottest laser engraving techn

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The influence of laser engraving technology on the development of flexo printing (II)

wrinkle roller is an important part of flexo printing machine. At the same time, it is also closely related to flexo printing plate and ink. When selecting and matching wrinkle roller, the following factors should be considered

1. Ink type to avoid bending and deformation caused by pressure on the swing rod. The inks used in flexographic printing usually include water-based inks, solvent based inks, UV inks and varnishes. Different ink types will vary greatly in the ink transfer of the corrugated roller. Even if the ink of the same nature, its quality and adhesion viscosity are also different, and there will be differences in ink transfer

2. Plate materials. At present, flexographic printing mostly uses resin plates, but some still use rubber plates. The plates of these two materials have different adsorption properties to ink. In resin printing plates, there are also inked plates and non inked plates. It will have a great impact on the ink transfer quality of the corrugated roller

3. Type of printing plate. On the spot full plate (glazing), low line and high line level printing have very strict requirements on the roller line and ink transfer volume. A slight error will lead to the decline of printing quality or printing failure

4. Substrate for printing. Paper, plastic film and corrugated board have different and influence on the adsorption and color of ink. The adsorption of plastic film on ink is poor, which requires that the ink transfer volume of the corrugated roller be lower, and that of paper be higher

5. Scraping mode. The ink scraping method also has a certain influence on the ink transfer effect of the corrugated roller. When making corrugated rollers, tell the manufacturer the specific scraping methods: rubber roller scraping, forward or reverse scraping, closed scraping system

in the process of using the corrugated roller, its maintenance is very important. In the past, many people didn't pay attention to the maintenance of corrugated rollers. Or the maintenance method is improper. In particular, there is no correct understanding of the cleaning of corrugated rollers, resulting in many quality problems. After several years of development, we have gradually realized the importance of the maintenance and cleaning of the roller to improve the printing quality, especially in the printing plants engaged in narrow width and wide width flexo printing

the maintenance of wrinkle roll includes the following parts:

1 Protect the surface of the corrugated roll when replacing it, and use a leather cover when storing it

2. The replaced corrugated roller should be cleaned in time

3. Place a magnetic filter in the ink tank to avoid metal impurities scratching the roller

4. Select high-quality scraper and blade type. It is recommended to use plastic scraper to better protect the wrinkle roll

5. Use a hole microscope to detect the hole. If wear and blockage are found, measures should be taken in time

in the past, when people encountered the phenomenon of light or uneven ink, they often looked for the reason of ink, printing plate or paper, but finally found that it was caused by hole blockage and decreased ink transfer. Now when you encounter a similar problem, you may first think of the problem of the wrinkle roll. However, some corrugated paper printing plants do not pay attention to the printing quality themselves. The head is also equipped with a device for mold correction and adjustment, not to mention the maintenance and cleaning of the wrinkle roller, and the blockage of the wrinkle roller seriously affects the printing quality. Such a long-term vicious cycle is detrimental to the development of the whole enterprise. If this goes on, it will also affect the overall development of flexo printing and corrugated paper printing in China. On the contrary, some large and medium-sized printing enterprises with joint venture and sole proprietorship in China attach importance to printing quality and every link in the printing process due to different management concepts and market awareness. This management experience and practice is worth learning from

generally speaking, the ceramic roller is not easy to wear. If it is found that the ink transfer volume decreases, most of the reasons are caused by the blockage of the roller hole. The existence of blockage in the hole can be clearly observed with a high-power hole microscope. Because the ink used in flexographic printing is easy to dry, it is not easy to dissolve and clean after drying, and the holes are blocked for a long time; In addition to affecting the amount of ink transfer, it will also shorten the service life of the corrugated roller. The long-term use of corrugated rollers with blocked holes will also increase the loss of ink, and there will be white exposure and dark ink during printing, especially for large-area field printing, which will have a greater impact. Therefore, it is very important to ensure the good cleaning of the embossing roller for stabilizing the printing quality

the cleaning of corrugated rollers is divided into daily cleaning and periodic cleaning

daily cleaning is to clean the wrinkle roll in time after shutdown, which can effectively prevent the ink from drying in the hole. Generally, special chemical cleaning agent is used to soften and dissolve the ink in the hole to achieve the purpose of cleaning. The specific cleaning method is to put the corrugated roller in the cleaning solution for a period of time, evenly spiral brush the surface of the corrugated roller with a special steel wire brush (copper wire brush is used for metal corrugated roller), and then rinse with water. Flexoclean cleaning agent is a kind of environmental protection product with strong pertinence and obvious cleaning effect. At present, it has been widely used in domestic flexo printing and corrugated paper printing industry. It can effectively clean water-based inks, solvent based inks, UV inks, varnishes, etc. After three years of promotion in the domestic market, many users have used fulaikeli products at present

for corrugated rollers with serious hole blockage, the effect of periodic cleaning will be more obvious. The principle of periodic cleaning is to use the principle of low-pressure spray washing the residue of baking soda impact hole to achieve the purpose of cleaning. With a laser rangefinder of 1064 nm, our wrinkle roller cleaning machine can clean a wrinkle roller for narrow flexo printing machine. The cleaning process takes only 3-5 minutes. The cleaning effect is obvious and the operation is simple. Nearly 100 flexo and corrugated printing plants in China have used our various models of cleaning machines

for manufacturers who have recently introduced flexo printing equipment, in addition to a more reasonable configuration of roll, they have also purchased roll cleaning equipment, which is undoubtedly good news for China's flexo printing. Attaching importance to printing quality shows that flexographic printing in China has entered a virtuous cycle

the influence of laser technology on the development of flexographic printing plate

another important application of laser technology in the field of flexographic printing is plate making. Laser engraving seamless printing plate realizes the continuous printing of flexographic printing, and extends flexographic printing to a broader field of packaging printing. The application and promotion of direct plate making technology using laser on photosensitive resin materials has created conditions for flexographic printing to finally achieve high quality

at first, laser technology only carved some lines and words on the sleeve printing plate made of rubber material. Due to the limitation of materials, the carved lines were not very high. This kind of printing plate sleeve can only print some field or simple words, such as cigarette tipping paper and exercise book lines, wrapping paper, wallpaper, etc. Later, in order to achieve continuous printing of higher-level colors and higher printing lines, several major flexographic material manufacturers in the world are developing a resin material that can be engraved by laser. After several years of efforts, companies such as DuPont and BASF have launched this material. Using these materials and laser engraving equipment, the printing plate line can reach more than 200 lines/inch and 1% point percentage. The actual printing effect on the machine has also been recognized by the industry, and the printing quality is close to the level of offset printing and gravure printing. In China, because this technology has just been popularized, it is not mature in technology and market. It needs a period of exploration and practice, and will not be popularized in the short term. In addition, due to the heavy burden of plate making materials and plate making equipment, the high plate making cost has also affected the development of laser direct plate making in China to a certain extent

flexographic printing is a special printing method that relies more on supporting materials and technology, and its development will be restricted by various factors. Flexographic printing in China has only developed in recent years. Although it has received attention from many aspects, the talents who are really proficient in this printing method are limited, and the technology and industry standards of flexographic printing are not yet perfect. In addition, too much reliance on imported supporting printing materials will lead to high printing costs, which is not conducive to the development of flexography in China in the future. ◎

information source: Greater China Printing Art

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