Gravure printing process

First, the gravure printing process film unwinding → tension control → printing the first color → dry → overprint the second color → drying → overprint the third color → dry → overprint the fourth color → drying → drawing → winding

Second, the gravure printing operation procedures 1. Preparations (1) Check the printing press around the dust, garbage and debris unrelated to printing, check the exhaust ventilation facilities are intact.
(2) Check whether the raw and auxiliary materials are adequate and whether they meet the printing requirements. The printing of plastic film requires that the substrate film to be printed meet the following requirements: 1 The surface is smooth and smooth, there is no obvious deadlock, yellow and black spots, holes, and no excessive wrinkles; 2 The average thickness error of the substrate film to be printed shall be Within 10% (1m printing width), the average thickness error calculation formula can refer to the requirements of dry composite substrate film; 3 Under the printing tension, the elongation of the substrate film to be printed should be within 1%; 4 The surface tension of the printed substrate film should be ≥ 40dyn/cm; 5 Prior knowledge of the affinity between the substrate film and the printed ink is required. For the film that is easy to dissolve and swell with the solvent in the printing ink, the printing speed and the ink concentration can be Bigger. When printing a coating layer of a coated substrate film, it is necessary to understand the adhesion of the coating resin to the ink.
(3) Check the roller quality. Note that the later color plate roller should be slightly larger than the previous color. For example, the circumference of the second color roller should be greater than 1% of the first roller surface, at least slightly larger or equal. It must not be smaller than the first color. Overprinting is correct. Check the roll pattern and color scale.
(4) Check whether the printing machine transports, feeds, feeds, dries, inks, hauls, and take-ups. Checks for resistance. Lubrication is injected into the lubricating oil, whether the oil path is unimpeded, and whether the instrument is in good condition. If the device has an ink viscosity automatic control device, the viscosity of the printing ink should be adjusted on the set value of 14-18 seconds (Zahn cup No. 3), and in which (upper) is poured into the mixed solvent, the same ink with the ink tank The pump is connected. Check the computer to automatically match the device.
(5) Mix the inks and select the same color inks as the color code.
2. When loading the plate, pay attention to the left and right sides of the plate. When clamping the cone, do not overtighten it to prevent the copper plate from bursting. If it is too loose, it will “run away” when printing. Install the plate roller according to the printing sequence. The printed color sequence in the printing is gold and silver ink → black ink → original blue → original yellow → original red (magenta version) → white version. When printed, it is exactly the opposite: white ink → magenta ink → yellow ink → blue ink → black ink → gold and silver ink.
3. The upper squeegee squeegee is generally made of thin steel sheet with a thickness of 0.15-0.55 mm. The angle between the squeegee and the tangent line of the contact point of the printing roller is between 15°-45°, less than 15°, the ink is not easy to be scraped, and is larger than 45°. The damage to the printing plate and the blade is heavy, and the printing plate is easy to handle. Chrome layer scratches. Squeegee pressure should not be too large, too large, easy to damage the printing plate; too small, not easy to scrape the ink. When the squeegee is used, you can use 280-400 mesh Whetstone, evenly coated with oil from left to right, or use 800 grit or more of metallographic sandpaper to squeegee the squeegee together with the knife holder. Grip it evenly on the fixture and prevent the scraper from damaging your fingers.
The squeegee is also overlapped with a hard lining and placed in the middle of the upper and lower clamping plates and bolted tightly. During operation, the bolt shall be tightened symmetrically from the middle to the left and right to eliminate blade bending. The length of the squeegee blade extending from the hard knife lining is 10-20mm, and the length of the squeegee blade is too long. The squeegee blade is soft, not easy to scrape, too short, the rigidity is increased, the scratch is too large, and the knife is damaged. Hard knife lining thickness is 0.8-1.8mm.
4. The intaglio rotary press, generally adopts a continuously variable transmission system to control the printing speed. In order to synchronize the printing units of different colors, a main motor and a continuously variable transmission are used to drive the entire printing system with a long rotating shaft. Turn on the ink pump and check if the ink pump is reversed. The main motor is started under the state in which the various plate clutches are disengaged, the transmission is checked for speed changes, and then the dryer and the blower are opened, the clutch is closed at a low speed, and the color registration is performed. Using the first color as a reference, start the start of the jog to perform longitudinal color registration of the second, third, and fourth colors; then, using the first color as a reference, perform second, third, and fourth color horizontal color registration The horizontal color registration is aligned with the hand wheel. Vertical and horizontal alignment, speed up the printing speed. If there is no automatic computer to the device, the printing speed should be no more than 40m/min whether it is a satellite type rotary machine or a combined type rotary printer. More than 40m/min, the naked eye can not follow the observation, generally controlled at 25-30m/min. Operators should pay close attention to color registration and adjust it manually at any time. If there is a fully-automatic computer-to-printer device, the operation mode should be applied to the automatic registration. In this case, the computer can automatically track and find the deviation, and it will automatically issue a correction signal to move the platen roller or substrate and realign it. .
On the imported equipment, there is a heating roller. After the substrate to be printed is unwound, the substrate can be heated to about 50° C. and then enter the first color printing unit. The warmth of the substrate facilitates the increase of adhesion and drying of the printing ink. After the ink is applied, the ink enters the dryer. The dryer temperature is set in a low-high-low format for quick drying. Can not be printed immediately after the high degree of drying, this organ reported that the surface of the ink layer is easy to form a layer of film, to prevent the evaporation of the solvent inside the drying, the results of the printed matter is not dry enough to stack anti-adhesion.
Different printing substrates have different tension control. For the BOPP film, the tension control per width of the rice is preferably set at 5-8kgf, that is, 49-78.4N, and the printing tension of the biaxially stretched nylon film is controlled at 8-10kgf, ie, 78.4-98N, and bidirectional. The tension of the stretched PET film was controlled at 10-12 kgf, ie, 98-117.6N. If it is less than 1 meter wide, multiply it by the ratio of its width to 1m, such as 0.7m, then the above tension is multiplied by 0.7. When printing a nylon film that has absorbed hygroscopicity, ink adhesion will decrease and the printing edge will overflow the ink. At this time, the first color dryer can be opened, and the first color roller can be placed in the second position. In the color position, one unit is shifted behind each color. The first color becomes the drying position of the nylon film, and the drying temperature can be set at 80-90°C.
5. Stop the main motor and stop the printing substrate feeding. The embossing roller lifts, the blade leaves the printing plate, stops the ink pump, pours out the remaining ink, cleans the surface of the printing plate until no residual ink is present, removes the printed substrate, closes the dryer for electric heating, and cleans the floor. When the plate is no longer in use, the plate is removed, the two ends are set up, and placed on a dedicated plate holder. If you do not use it for a long period of time, pack it in a warehouse. A group of printing rollers should be put together, to avoid confusion, to be labeled on the outside, and to indicate how many impressions have been printed so that they can be used at any time.

Third, the color ink ink palette is an important technical work in the printing operation, the deployment of color people must understand the principle of three primary colors superposition, can make full use of the color light additive mixing method and pigment subtractive color mixing principle.
1. The principle of coloring (1) When the plate-making factory sends the plate to the printing house, it is also delivered together with the proofs. In order to obtain the same print product quality as that of the same sample, you should use the color code of the three primary color materials printed next to the proofing component to select the ink. The hue of the ink is the same as the color standard as much as possible to reduce the color difference so that the quality of the printed product is the same as that of the proof sample. .
(2) The tinting of printing ink should adopt the same type of stereotyped ink with the same hue produced by the ink factory as far as possible. The color saturation (that is, the saturation) of the final ink is better than the color saturation of the ink that is blended with the two colors of ink. High degree.
(3) If you want to use several hue of ink toning, you should try to make use of color inks that are close to the color.
(4) In the deployment of light-colored inks, white ink is the main ingredient, and a small amount of primary ink is added to the mixture.
(5) During the printing of plastic packaging materials, in order to obtain a pale color ink and still maintain the viscosity of the ink, a diluting agent can be used. The diluting agent is actually a pigment without maintaining the other components in the ink, and the viscosity is adjusted to the viscosity. Ink transfer material. When thinner inks are used to formulate light-colored inks, the ink's color becomes lighter and the viscosity of the ink decreases. Due to the decrease of the binder in the light-colored ink formulated with the diluent, the ink adhesion and the thickness of the film are reduced.
(6) When matching colors, the type of ink should be reduced as much as possible. The more types of color matching inks, the higher the proportion of achromatic colors, the lower the brightness of color matching inks, the lower the glossiness, and the lower the saturation, the color inks will lose their vivid color. sense. For this reason, two hue inks can be used, and no three hue inks are used for dispensing.
(7) Different manufacturers, different models of the same manufacturer, different manufacturers of different types of ink can not be used for dispensing, to avoid the occurrence of gel, precipitation, discoloration and other accidents.
2. The correct use of complementary color relationship According to the color subtractive color principle complementary color, complementary color addition achromatic. In the deployment of color inks, complementary colors should be used correctly and complementary colors should sometimes be avoided. For example, in the preparation of color or dilute the original color ink, the complementary color ink should be avoided as much as possible, because the more mixed color, the more achromatic components to increase, the color saturation decreases, darkening color. Another example is the color shift occurred in the deployment of ink, when you need to correct color, you can use the principle of subtractive color complementary color correction, if the yellowish ink, in order to eliminate the yellow tone, you can add a little purple blue tone ink in the ink. Because yellow and blue purple are complementary colors, the two colors are mixed in achromatic colors. If you need to adjust the hue when you adjust the ink, you can also use complementary colors to solve. For example, in the production practice, when the blue ink reddish needs to be changed to a yellowish tone, only a small amount of green ink is added to the ink. Because the red and green light reflected by the ink is mixed with yellow light, the reddish blue ink will turn yellowish blue ink. Similarly, if the blue ink is yellowish and needs to become a reddish blue ink, as long as a small amount of blue-violet ink is added, the blue-violet ink reflects red light and blue light, and the yellow hue reflects red light and green light, and the two ink colors are mixed, except Apart from achromism, the total shade of light is a reddish blue tone. When the yellow ink is blue, add a small amount of orange and the yellow ink will turn red.
In everyday production, in order to make the white ink whiter, by adding a small amount of ultramarine (about 1%), the yellow tint in white can be eliminated. When you feel that the black ink is not dark enough, you only need to add a part of the light blue and black, and the black ink will become dark. As in printing, adding a small amount of indocyanine blue to the black ink can eliminate the yellow hue in the black ink, and the black ink will be darker.
3. Proportionality and Method of Toning (1) The toning ratio of the intermediate and complex colors is shown in Table 32-1.

Table 32-1 Tonality ratios of inter and mixed colors

(2) The color ratio of the mixed color using the three primary color inks is shown in Table 32-2.

Table 32-2 Mixing Colors