Category：Industry news Addtime：2019-03-23 10:39:11 Clicks：468 次
The printing of plastic film requires that the substrate film to be printed meets the following requirements: smooth surface, no obvious rigidity, yellow and black spots, holes, excessive wrinkles; the average thickness error of the substrate film to be printed should be less than 10% (1 m printing width), the calculation formula of the average thickness error can be referred to the requirements of dry composite substrate film; under printing pressure, the elongation of the substrate film to be printed. The rate should be less than 1%, the surface tension of the substrate film to be printed should be greater than 40 dyn/cm, and the affinity between the substrate film and printing ink should be known beforehand. For the film which is easy to dissolve and swell with solvent in printing ink, the printing speed and the concentration of ink can be higher. When printing coating layer on coating substrate, it is necessary to know the adhesion between coating resin and ink.
Note that the plate roll of the latter set of colors should be slightly larger than that of the former. For example, the circumference of the second set of colors should be greater than that of the first set of colors by 1%, at least slightly larger or equal, and absolutely not smaller than that of the first set of colors, otherwise the overprint can not be correct. Check the pattern and color mark of plate roll.
If there is an automatic ink viscosity controller on the equipment, the viscosity of printing ink should be adjusted at the set value of 14-18s, and mixed solvent should be poured into it to connect with ink pump for ink tank. Check the computer automatic alignment device.
_Mix the ink well and choose the same primary color ink as the proofing color standard.
_Gravure Printing Machine
_Pay attention to the left and right sides of the plate when installing the plate. When clamping the cone, it should not be too tight, so as to prevent the roll from cracking, loosening and "escaping" when printing. Install plate rollers according to printing color sequence. The order of printing color is gold and silver ink black ink original green original yellow original red white ink. In positive printing, the opposite is true: white ink magenta ink yellow ink green ink black ink gold and silver ink.
Ink Scraper on Gravure Printer
_ink scraper usually uses thin steel sheet, the thickness is between 0.15 mm and 0.55 mm. The angle between the scraper and the tangent of the contact point between the scraper and the printing roll is between 15 ~45, less than 15, and the ink is not easy to scrape; if the angle is greater than 45, the damage to the plate and the scraper is serious and the chromium plating layer of the printing plate is easy to scrape The pressure of the ink scraper is not too high, too big and easy to damage the printing plate; too small. It is not easy to scrape the ink. When the ink scraper is used out, it can be grinded with 280-400 mesh oil stone evenly from left to right, or with more than 800 mesh metallographic sandpaper and oil to remove the ink scraper together with the tool holder and clamp it on the fixture to grind evenly, so as to prevent the scraper from hurting peoples fingers.
After overlapping the ink scraper with the hard blade lining, place it in the middle of the upper and lower clamping plates, and tighten it with bolts. During operation, the bolts should be tightened symmetrically from the middle to the left and right ends to avoid the blade bending. The length of the hard lining of the scraper is 10-20 mm, which is too long. The scraper is soft and not easy to scrape. It is too short, rigid, scraping too big and vulnerable to damage. The thickness of hard blade lining is easy to be 0.8-1.8 mm.
Initial Printing of Gravure Printing Machine
_Gravure rotary press generally adopts stepless speed change system to control printing speed. In order to synchronize printing units of different colors, a main motor and a continuously variable transmission are used, and a long rotating shaft is used to drive the whole printing system. Turn on the ink pump and check whether the ink pump is reversed. Start the main motor when the color plate clutch is separated, check the transmission speed, then turn on the dryer and the blower, and close the clutch at low speed for color matching. With the first color as the reference, start the point switch to calibrate the second, third and fourth vertical color matching; then with the first color as the reference, the second, third and fourth color crosswise color matching is carried out, and the crosswise color matching is fine-tuned by handwheel. Accelerate printing speed after alignment of vertical and horizontal color registration. If there is no automatic computer counter-printing device, the printing speed should not exceed 40 m/min, whether it is a satellite or a combination wheel. Over 40 m/min, the naked eye can not follow up, generally controlled in 25-30 m/min. Operators should pay close attention to the sexual situation and adjust it manually at any time. If there is a full-automatic computer plate-setting device, the operation mode should be typed on the automatic plate-setting device. At this time, the computer can automatically track the deviation, and automatically send a correction signal to make the plate roll or base material move and re-align.
On the imported equipment, there is a heating roller. After the printing substrate is unwinding, the substrate can be heated to about 50 C, and then enter the first color printing unit. Warm and hot substrates are conducive to the improvement of adhesion and drying of printing ink. After the ink is coated, the ink enters the dryer, and the temperature distribution of the dryer is set in the form of low-high-low, which is convenient for rapid drying. Can not be printed immediately into a high degree of drying, so it is easy to make the surface of the ink layer into a film, volatile drying of solvent in the tissue, the result of printing is not dry enough, easy to anti-stick in stacking.