Causes and elimination of cutting thread in the pr

2022-07-25
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Causes and elimination of "knife thread" in the process of plastic printing

Shandong Huayu, as a successful example of cooperation between Chinalco and Huasheng Jiangquan group, has overload protection and other functions. Knife thread often occurs in the process of plastic gravure printing. The causes are very complex, involving plate making, ink, doctor blade and environment, etc. This paper analyzes and discusses them for reference

1 in terms of printing plate

the surface finish and hardness of the chromium plating layer on the printing plate will have an important impact on the production of the cutting thread. The pigment of the ink used in plastic gravure printing is generally dispersed in the connecting material in the form of particles. In the printing process, after the ink is full of holes, the excess ink is scraped off by the scraper, and constantly rubs the surface of the printing plate. If the hardness of the chromium plating layer on the surface of the printing plate is not enough, it is easy to be scratched by coarse-grained ink and produce knife threads

on the other hand, if the plate cylinder is not well polished during plate making, and the plate has small polishing lines or plate lines are too deep, during the printing process, the ink will remain. With the development of intelligent technology, it cannot be scraped off by the scraper, and irregular and very fine knife threads will be generated when transferred to the printing materials. Therefore, special polishing equipment and special polishing sandpaper should be used for polishing

in addition, the processing accuracy and installation accuracy of the drum should be strictly controlled to prevent the eccentricity from exceeding the standard, so as to avoid the impact on the doctor blade during high-speed printing

2 ink

if the ink used for plastic gravure printing is not fine enough, the pigment particles are too large or mixed with granular impurities, it will lead to the appearance of knife threads. Therefore, the ink with good quality should be selected, and its pigment particles should be less than 10m. A filter device should be added to the inking system, and it should be checked frequently to prevent the coarse particles of impurities in the ink from damaging the printing plate and the doctor blade. If the ink viscosity is too large and the drying is too fast, the relative friction between the printing plate cylinder and the doctor blade will be increased, making it difficult for the doctor blade to scrape off the excess ink on the plate and form a knife wire. Therefore, we should control the viscosity of the ink. For the ink that dries too fast, we can use slow drying solvent or dilute the ink

in addition, if the ink is diluted irregularly, the use of insoluble solvents will lead to the precipitation of pigments in the ink and the formation of large particles, resulting in knife threads. Therefore, the solvent matching with gravure printing ink should be selected. If the anti-static performance of the ink is poor, or the lubrication performance is poor, it will also lead to the cutting thread phenomenon. Therefore, it is necessary to strictly control whether the quality indicators of the inspection ink are analyzed

source of confidence: Jiangyin Lida printing and Packaging Machinery Co., Ltd.

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