All round sealing of the hottest film gravure prin

2022-07-25
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Film gravure printing dirty all-round blocking

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core tip: in the process of film gravure printing, dirty faults occur from time to time. There are many reasons for irregular fouling. This paper makes a detailed analysis of the irregular fouling fault from the aspects of gravure cylinder manufacturing, scraper selection and installation, ink and dilution solvent, workshop environment and production operation

[China Packaging News] in the process of film gravure printing, dirty faults occur from time to time. There are many reasons for irregular fouling. This paper makes a detailed analysis of the irregular fouling fault from the aspects of gravure cylinder manufacturing, scraper selection and installation, ink and dilution solvent, workshop environment and production operation

I. gravure cylinder production

1. Cause analysis

(1) if the hardness of the chromium plating layer on the surface of the gravure cylinder does not meet the minimum requirements, the non graphic areas on the surface of the gravure cylinder will be (2) "small and fine": the accuracy is one of the permanent pursuit of various instruments and equipment. 1. It is easy to generate excessive friction with the scraper and cause wear, and the worn areas will be immersed in ink, Thus, it is transferred to the film to cause a dirty fault

(2) if the polishing treatment of the gravure cylinder after chromium plating is not sufficient, the surface of the chromium plating layer will be rough, and the machine will be dirty when used

(3) the gravure cylinder has plate making defects, which will cause ink marks to remain, resulting in dirty failure

2. Countermeasures

(1) ensure that the gravure cylinder has smooth surface, high hardness, good wear resistance, and long service life due to frequent mountain fires in North America

(2) determine the maximum printing capacity of each gravure cylinder by combining the hardness, hole depth, hole distribution and other factors of the gravure cylinder. Once this value is exceeded, it is necessary to re chrome the surface of the gravure cylinder

(3) before formal printing, the surface of the gravure cylinder shall be comprehensively ground with 800 1000

132 mold proof sealant for Building II. Selection and installation of scraper

1. Cause analysis

(1) the hardness of scraper is not appropriate

(2) the installation method of the scraper is incorrect, the pressure of the scraper is insufficient, the angle between the scraper and the gravure cylinder is inappropriate, the grinding of the scraper is insufficient, or the distance between the scraper's ink scraping point and the ink transfer point is improper

2. Countermeasures

(1) select the self grinding scraper with compact material and moderate hardness

(2) ensure that the scraper is installed correctly and stressed evenly. The lining knife (also known as "auxiliary knife") generally selects a corrosion-resistant flat steel plate with a thickness of 0.5mm. The installation position should exceed the clamping edge of the knife rest by 15 ~ 20mm, and the scraper position should exceed the top of the lining knife by 3 ~ 5mm. The angle between the scraper and the gravure cylinder shall be 55 ° ~ 60 ° and inclined upward

(3) during the operation of the equipment, the swing amplitude of the scraper shall be 5 ~ 10mm, and the swing cycle shall be 2 ~ 5S

(4) before formal printing, the scraper must be fully ground with 1000\

(5) according to the drying speed of the ink, set a reasonable distance between the scraping point of the scraper and the ink transfer point

(6) for the ink that has not been scraped off in the non graphic area, the ink can be dried in time by appropriately reducing the running speed of the equipment, adding a blow pipe in the non graphic area of the gravure cylinder, adding anti fouling additives in proportion to the ink, or adding quick drying solvent without causing plug failure, so as to avoid the fouling failure caused by transfer to the film surface

III. ink and diluting solvent

1. Cause analysis

(1) the resin binder and pigment particles in the ink are too large to be fully dissolved by the diluting solvent, causing a large number of particles to gather at the edge of the knife. Although the swing of the scraper can grind and disperse these particles, it will still leave ink marks in the non graphic area of the gravure cylinder, resulting in dirt

(2) the ink viscosity is too high, resulting in the deepening of the wear between the gravure cylinder and the scraper, resulting in the dirty fault

(3) the diluting solvent of gravure printing ink is mostly mixed solvent. During the high-speed operation of the equipment, a large amount of fast drying solvent will volatilize, while the slow drying solvent will gradually accumulate in the ink tank. Even if new diluting solvent is continuously added for adjustment, the balance proportion of the mixed solvent is also changing, resulting in slow drying of the ink, weakened solubility and poor scraping effect, Thus, the residual ink mark is transferred to the surface of the film to produce a dirty fault

2. Countermeasures

(1) dilute the solvent with strong solubility, place the magnetic dispersion rod in the ink tank, add anti-static agent if necessary, and require the ink manufacturer to refine the ink. The ink from different manufacturers cannot be mixed

(2) for inks of different colors, filter with the corresponding mesh number. In addition, 80 ~ 100 mesh filtration is installed in the circulating ink conveying device, and the ink returned from the ink tank can be printed after filtration

(3) use the ink with a short storage time to reduce the retention time of the ink in the ink tray and the circulating ink conveying device. For the ink with a retention time of more than two hours, filter it with more than 150 meshes, adjust it to the normal use viscosity, and fully stir at the same time to make the ink have good solubility

(4) the viscosity of spot color and monochrome inks should be moderate to ensure the stability of ink viscosity during gravure printing. Now the commonly used benzene free and ketone free inks have higher requirements on viscosity. In order to stabilize the ink viscosity, the ink viscosity should be tested every half an hour, and the dilution solvent should be added in time

(5) reuse the remaining ink by adding new ink, and determine the mixing ratio of new and old ink according to the storage time of the ink, subject to the full dissolution of the ink

IV. workshop environment

1. Cause analysis

improper temperature and humidity in the production workshop and poor air cleanliness may cause dirty faults

(1) if the temperature in the production workshop is too high, the volatilization speed of the diluted solvent and the drying speed of the ink will be faster, which will be listed as a national strategic emerging industry. If it is not adjusted in time, the ink viscosity will increase, resulting in difficulties in scraping, which is not only easy to damage the gravure cylinder and scraper, but also cause dirty faults

(2) if the humidity in the production workshop is too high, the solubility of the ink will become poor, resulting in the accumulation of ink particles and the dirty fault

(3) there is a lot of dust in the air of the production workshop. If the equipment is not cleaned regularly, the dust is easy to be adsorbed on the film surface under the action of static electricity, and transferred to the gravure cylinder surface during the printing process, or accumulated in the ink, resulting in a dirty fault

2. Countermeasures

the temperature of the production workshop should be controlled at 18 ~ 28 ℃ and the humidity should be controlled at 45% ~ 75%. At the same time, the sealing of the gravure production environment should be maintained, and the air filtration system should be installed to maintain a certain positive pressure environment in the production workshop. At the same time, pay attention to the regular cleaning of the equipment, especially around the ink tank. It is best to clean it once a day

fault analysis and Countermeasures for film gravure printing dirty 5

v. production operation

1. Cause analysis

improper production operation can also cause dirty faults, such as inadequate pre press preparation, improper equipment commissioning, etc

2. Countermeasures

(1) film gravure printing enterprises should make preparations before printing, and include the requirements on equipment cleaning, installation and commissioning of gravure cylinder and scraper, ink allocation, etc. in the daily operating procedures, which should be strictly implemented by the operators

(2) when the non graphic area of the gravure cylinder is immersed in ink due to improper operation, increase the operating speed of the equipment to about 150m/min, adjust the scraper pressure to the normal state, and then keep the two running in for about 5 minutes. The formal printing can be carried out after it is determined that the dirt fault will not be caused

(3) when the shutdown time exceeds 20 minutes, keep the scraper and the gravure cylinder surface away from each other to reduce the wear of the scraper and the gravure cylinder. When starting up again, fully grind and clean them

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