How to print on white paper
A lot of packaging, brochures, are inseparable from the white paper, so to do other products, the premise is to do a good job of white paper, many printing factories are dead in this step, the things made are very rough, the following will introduce you to the printing of white paper, how to print is the best. Cigarette box packaging, wine boxes, food boxes and other box-type packaging and decoration printing products are often printed with 250-400g/m2 whiteboard paper and card stock, and the maximum paper thickness that can be printed by the offset printing machine is 0.9mm, but the thickness of the paper to be printed is often only between 0.04-0.3mm under normal circumstances. The difference between whiteboard paper and coated paper, offset paper, and letterpress paper lies in the thickness of the paper, and in the process of offset printing whiteboard paper, the paper feeding part, the embossing part, the color sequence arrangement of the printing, and the balance of ink and wash should be adjusted accordingly. 1. Cylinder lining and pressure adjustment When printing whiteboard paper, the center distance between the printing plate cylinder and the rubber cylinder remains unchanged, only need to adjust the center of the embossing cylinder and the rubber cylinder, and the center distance of the cylinder can be expanded by 0.20-0.4mm when printing 250-450g/m2 whiteboard paper, due to the poor smoothness and roughness of the whiteboard surface, the tightness of the paper is far less than that of coated paper, and the printing pressure should also be increased accordingly. Such as printing 400g/m2 whiteboard paper, The gap between the printing plate cylinder and the rubber cylinder is 3.95mm, the gap between the rubber cylinder and the embossing cylinder is 3.40mm, the total package of the printing plate cylinder is 0.65-0.75mm, and the total liner of the rubber cylinder is 3.15-3.35mm (measured with a micrometer), if the paper is changed from thick to thin, the thickness of the reduced thickness should be added to the rubber cylinder from the lining thickness of the printing plate liner, if the paper during printing is changed from thin to thick, a certain thickness is subtracted from the rubber cylinder liner, and the corresponding thickness is added to the liner of the printing plate cylinder. 2. Adjustment of offset paper feeding part (1) When printing whiteboard paper, the air volume of the suction nozzle and paper blowing nozzle of the paper feeding part should be increased accordingly. (2) The paper nozzle and the paper feeding nozzle should be replaced with a rubber rubber ring with a larger diameter and a larger thickness, and the tension gauge pressure spring can be replaced with a steel wire with a diameter of 1.5mm; (3) When printing whiteboard paper, the double control or gap of the offset printing machine should also be increased accordingly; The distance between the pressing tongue and the paper feeder of the side gauge and the front gauge, and the distance between the safety bar and the cardboard should be increased. (4) The distance between the paper pad and the surface of the embossing cylinder and the distance between the paper pad and the cardboard should be increased, and the distance should be about equal to the thickness of the paper plus 0.3mm. 3. Color sequence arrangement during printing (1), the products printed on whiteboard paper have the Hong Kong version of the field, and there are words, lines, and patterns. For example, the postal department's express mail envelopes, wine boxes, cigarette box outer packaging (strip boxes) and other printed products, the color sequence of printing is best to print text, lines, patterns, and then put the full version on the machine at the end, so as to avoid the dirty and dirty back caused by the collision of the paper when the whiteboard paper is thicker and the imprint is not dry. (2), the dark color in the front of the print, the light color in the back of the print, because the dark color of the ink has strong hiding power, strong adhesion, put in front of the first printing, easy to overprint accurately; The hiding power of the light-colored ink is weak, and it is not easy to observe when it is placed in the back to print a little out of order, and the effect of overprinting is much better. (3) Often in a printed product, there are half-tone four-color electric dots, and there are continuous patterns, texts, and lines. The four-color electrical distribution point should be printed first, which is conducive to accurate overprinting and reduces the impact of paper expansion. Then print continuous patterns, words, lines, in the arrangement of the printing color sequence to identify the priority, first difficult and then easy is more appropriate. (4) If the weather is hot, when the whiteboard paper prints monochrome, the paper moisture content is uneven, the wrinkles are uneven, and the surface strength of the paper is poor, which causes powder and hair loss, etc., you can also first make a blank print with water, which can solve the phenomenon. Fourth, how to prevent sticking and dirty printing whiteboard paper (1), try to use the original barrel ink when printing the full plate, do not add 6# inking oil, and appropriately add some desticking agents and anti-sticking agents; Do not add oil when it is hot. Although the printing anti-sticky dirty sprayer contains pure plant-based materials, dispersion and fluidity are good, but the use of powder spray will directly affect the surface gloss of the printing product, make the ink color not bright, and pollute the environment, and have an impact on the accuracy of the offset printing machine. (2) The surface of the whiteboard paper is rough, the quality is loose and the ink absorption is large, and the flatness is poor, so the base color should be printed first when printing the full plate, and then the dark color should be printed, and the background color should be darker, and the ink color should not be too large. If the flatness of the whiteboard paper is good, then, when printing the full plate field, the dark color should be printed first, and the amount of ink should be printed sufficiently, so that the back is not sticky, and then the background color is overprinted thinly, so that the finish of the printing product will be better, at the same time, pay attention to the balance of ink and water, and control the moisture size of the printing plate layout. In addition, when the offset printing machine prints whiteboard paper, because the paper is thicker, a number of whiteboard paper is blocked into the embossing and the rubber roller to easily cause "stuffy car", so it is necessary to carefully and meticulously adjust the device of the electrical appliances such as double-sheet control, skew control, and pre-punch control before printing, and the distance between the double-sheet control wheel and the feeding roller during the double-sheet control shall not be less than two sheets of paper thickness, but it shall not be greater than three sheets of paper thickness, otherwise the paper of the arch will stop when passing through the controller; Or the double sheet has passed through the controller, and the two contacts of the controller power supply have not yet touched, so the purpose of controlling the double sheet cannot be achieved. Clean up the dust, dirt or insulation on the surface of the double-sheet control wheel and the feeding roller, or the surface of the two contacts at the power control place in time to prevent the failure of the double-sheet control system, the occurrence of "stuffy traffic", and the failure of the rubber roller and the imprint cylinder in traffic jams.