Several technical problems in the drum screen printing (1)
In recent years, with the rapid development of the packaging industry, users have become increasingly demanding for metal drums for metal packaging containers. For this reason, steel drum packaging companies have also started to adopt new technologies in the manufacture and coating of steel drums. , new technology, in order to improve product quality. In addition to paint on the surface of steel drums, users are now advertising on the surface of steel drums in order to promote their own products. The traditional production process can not meet the user's requirements, so beautiful, generous, easy plate making, cheap, printing methods are diverse, flexible, easy to grasp the screen printing technology, soon to be applied in the steel barrel enterprises, and Has become a beautiful scenery on the steel barrel. However, because most steel drum companies lack the screen printing technology, some technical problems often occur in the actual production operations. The following analysis of several common problems.
One, steel drum printing is easy to block (blocking the net)
Sealing refers to the phenomenon that the screen printing plate graphic can not transfer ink to the steel drum during printing. This phenomenon will affect the quality of the drum screen printing, because the text and graphics will appear incomplete, so that it can not be identified. There are several reasons for this phenomenon:
(I) Effects of temperature, humidity and ink properties at the production site
Screen printing has certain temperature and humidity requirements for the production site of the printing. If the production site has high temperature and low relative humidity, the volatile solvent in the ink will evaporate quickly and the viscosity of the ink will increase, thus blocking the network. Hole; In addition, if the residence time is too long, there will be paste version blocking phenomenon, the longer the paste is more serious; second, if the ambient temperature is low, the ink flow is poor, it is easy to produce paste version, blocking version. Most steel drum manufacturers use screen printing, their work sites are open air, and the temperature and humidity of their production sites must be affected by the local natural climatic conditions. Especially in the northwestern region of China, the natural climate is dry, the solvent in the ink evaporates quickly, and the plate-closing phenomenon is prone to occur. Therefore, attention should be paid to such problems when operating.
(B), the influence of screen version body
The prepared screen plate is rinsed with water before use, and dried before use. If printing is not performed for a long time after making a good version, dust will adhere to more or less during the preservation process, and if it is not cleaned during printing, it will result in a cover plate.
(three), the reasons for the pressure during printing
Screen printing of steel drums, sometimes due to the small volume, frequent replacement, so generally use manual printing. In manual printing, the operator's arm is mainly used to adjust the embossing force. If the imprinting force is small, the printing plate cannot touch the surface of the drum and printing cannot be performed. Excessive embossing force will cause the squeegee to bend and deform. The contact between the squeegee and the wire mesh and the steel drum is not in line contact but surface contact. In this way, each squeegee will not be able to scrape the ink and leave it. Residual ink, after a certain period of time, it will cause conjunctival closure.
(4) Inappropriate clearance between screen plate and steel drum
The gap between the screen plate and the steel drum must not be too small. The gap is too small. After the squeegee is printed, the screen plate cannot be separated from the steel drum, but it is adhered to the steel drum. When the screen plate is raised, the bottom of the printing plate adheres. A certain amount of ink, it is also easy to cause the seal.
(e), the impact of ink
The ink requirement for screen printing is not high, and it can be applied to various types of inks. Such as oil, water, synthetic resin type, powder and other inks can be used. Therefore, the size of the pigments and other solid materials in the ink is uneven. When the particles are large, the phenomenon of the seal is liable to occur. In addition, the number of screen meshes to be used and the area of ​​the through-holes are smaller than those of the ink, making it difficult for coarser particles of ink to pass through the mesh and causing screen closure. Due to the large size of the ink particles caused by the seal, you can use better quality, small particle size, fine ink to solve.
The ink is dried too quickly during the printing process, and it is also likely to cause a seal. In order to print graphics on the surface of steel drums, the most prominent feature of their requirements is drying faster. Therefore, it is best to use a volatile drying ink when printing graphics on steel drums. In order not to seal the ink, it is necessary to select an appropriate solvent to control the drying speed during printing. In the selection of ink to take into account the impact of climatic conditions, under normal circumstances, the use of fast-drying ink in winter; in the summer should be added to the ink in the drying agent, if the use of late drying agent also occurs in the phenomenon of plate closure, you must replace other Type ink.
In the printing process of steel drums, the ink viscosity should not be too high, because the viscosity is too high, the ink flow is poor, and it is easy to cause the closure, while the graphic on the steel drum is generally small, the screen version Ink consumption is correspondingly small. If the ink is over-prepared at one time, the ink solvent evaporates, resulting in increased viscosity of the ink, and it is also prone to netting. Therefore, the amount of ink used for each preparation should be appropriate.
After the failure of the sealing network, according to the nature of the ink on the screen plate, scrub with an appropriate solvent. The essentials of scrubbing are to begin with the printing surface, gently wipe from the middle to the periphery, check the plate after wiping, if any defects should be repaired in time, and can be reused after repair. It should be noted that the screen plate can not be used for multiple generations of the plate, because the plate becomes thinner each time it is scrubbed. If the plate is damaged due to a large amount of defects, the plate has to be replaced with a new one.
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