“Paddling Method” Quickly Eliminates Crinkle Failure in Non-Carbon Paper Printing

Carbonless paper is also called pressure sensitive recording paper. It is a commonly used printing material for multi-link reports, bills, and computer terminals. It is easy to use, fast, and popular with users. It is widely used in aviation, postal services, telecommunications, commerce and trade. Other service industries. Since the carbonless paper is lighter and thinner, the stiffness is relatively poor. When the moisture content of the base paper is not controlled properly, the edges of the paper are likely to be curled or deformed after unpacking. In this way, the edge of the paper is likely to wrinkle when printed by an offset printing press. , not only the product's printing quality does not meet the user's requirements, but also to the machine's normal printing caused some obstacles.

1. Analysis of printing wrinkle failures

Our company used the J2205 Offset Two-color Offset Printing Machine to print on the Union and Zoomlion carbonless paper (large size four opening 59.5×44.3cm specifications) without any problems, and when printed to 45 grams of yellow lower carbonless paper, the paper There are frequent wrinkling failures on both sides, resulting in the problem of the quality of the form layout deformation and text lack of strokes, which also affects the accuracy of the products of the couplet, and does not meet the quality requirements for use. After this problem appeared, even though the operator had to adjust the light printing pressure, check the flatness and elasticity uniformity of the blanket, and repeatedly adjust the pressure of the roller to bite the paper teeth, it would not help, and the phenomenon of wrinkling of printing could not be eliminated. After cutting, the semi-finished raw paper cannot be returned or replaced. The customer hurries to press the goods. The situation is more difficult and I do not know what to do. In this regard, the author observed through the scene and inspection, found that this joint is prone to wrinkle after the printing of carbon-free paper, curl and deformation of the edge of the situation, in addition, the left and right edges of the paper does not correspond to roller teeth, so with the printing process With the rapid rotation of the drum, the two sides of the paper fall backward due to not being bitten by the teeth, so that the left and right sides of the paper and the middle paper edge do not maintain a straight line and synchronous rolling, so that the pressing effect of the drum is easily achieved by the effect of the pressing of the drum. The uneven paper produced several wrinkles on both sides of the trailing edge. After analyzing the reasons, the mind of the author immediately flashed a solution to the problem, adding cardboard cushions to the left and right sides of the sheet, using the elasticity of the blanket, and laying the cardboard through the liner. Tighten the paper to eliminate the wrinkle of printing.

2. Application of "add pad method" to quickly eliminate printing wrinkles

The so-called “padded method” is to place two cardboard strips of appropriate thickness and width respectively on the corresponding positions of the impression cylinder and the printed sheets. The specification of the printed sheet is 44.3×59.5 cm. In order to eliminate the phenomenon of printing wrinkle quality failure, the authors applied a white paper strip with an appropriate width and thickness to each side of the printed sheet (59.5 cm in the direction of the specification) to tighten the sheet. Embossing the paper surface, thus quickly and better avoid the wrinkling phenomenon of the printed sheet, not only realizes normal production, but also guarantees the quality of the product. The specific approach is: take a 250 g thick white paper, respectively cut out a width of 5mm, a length of 430mm cardboard two, then use 5 × 430mm specifications of double-sided adhesive, respectively, align the sticky side of these two cardboard On the surface, a layer of waxed paper is peeled off, and then a large four-sheet paper is placed on the paper transporter. The machine is normally positioned so that the paper enters into the impression cylinder and bites the teeth. The machine is then moved to a suitable position and the two cardboards are separated. One by one, pasted on both sides of the impression cylinder and corresponded to the left and right sides of the imprinting sheet. When affixing, two edges of the 430-mm-long paperboard are required for gluing. The distance from the corresponding edge of the imprinting sheet is approximately 13mm, that is, the length of two cardboard strips. The edges are exactly aligned with the trailing ends of the sheets, so that when the cylinder is imprinted, the left and right sides of the sheets come into contact with the surfaces of the two cardboard strips, and then the hard cardboard strips force the blankets to sink so that the sheets are slack. Tightening is achieved during tensile deformation, that is, the machine presses the edges of the left and right sides of the paper first in the imprinting state, thereby playing a role of tensioning the paper surface, thereby better eliminating wrinkling of the paper printing. . It is worth noting here that thin paper with uneven printing paper is applied on both sides of the embossing cylinder with a cardboard strip (corresponding to the two sides of the printing sheet). The old one should be replaced with a good one so as not to push out a good one out of the two. Traces of traces, resulting in the emergence of two light traces when printing flat net or field version. In addition, when the poorly flattened paper is printed, the two cardboards on the impression cylinder should be peeled off, and the adhesive remaining on the cylinder should be cleaned with gasoline to avoid the occurrence of a good blanket impression. Deformation phenomenon. If the wave deformation of the paper edge is particularly severe, the thickness of the paperboard strips may be increased (if more layers of whiteboard paper are used), and then the paperboard corresponding to the backside of the blankets shall be cut off the corresponding area and thickness. In this way, the “hanging” state of both sides of the blanket can be used in the imprinting to form more expansion space, so that the tension amplitude obtained by the printing sheet can be further increased. The printed sheets are not prone to cracking, and the damage to the blanket is also lighter, which can play a good role in eliminating wrinkles from paper printing.

3. Technical tips for reducing or preventing wrinkling

The practice of production process shows that uneven printing is the main reason for printing wrinkles. However, machine defects are also likely to induce print wrinkle failures, such as the structural characteristics, position, and pressure of the paper teeth, and the characteristics of the lining, the flatness of the rollers, and the printing pressure. These defects may also cause printing thin papers to appear. Wrinkle disease. Therefore, from the technical point of view of preventing wrinkling from printing, the printed sheet should not be slightly slipped or deformed, especially bite, after the printed sheet is pressed by the paper teeth. If the two paper corners of the paper edge fall backward, it is very easy to produce printing wrinkle failure phenomenon. Therefore, during the printing, the paper angles on both sides of the left and right (width) of the print sheet should correspond to the bite teeth, especially It is printed thin paper, the printed sheet is not bitten by the bite, and the probability of occurrence of printing wrinkles is even higher. Secondly, in the positioning of printed sheets, the bite paper teeth should be bitten as much as possible, and the pressure of each bite should be adjusted enough and kept even. Third, the lining should be kept flat and compact, and the coefficient of compression deformation should be minimized. Fourth, under the premise of maintaining the proper resolution of the printing plate surface, printing is performed with the lightest printing pressure. Through the control of these technical measures, the occurrence of printing wrinkle failures can be minimized and avoided.

After a reasonable adjustment of the machine, the thin paper with a severe distortion in the printing paper surface still suffers wrinkling failure. Only the cardboard strip is used to stick the two sides of the impression cylinder, and the paper surface in the imprinting is tightened to eliminate the paper surface. The purpose of printing wrinkles. Although this practice is contrary to the suspicion of printing the "Sanping" theory, successful practice has shown the feasibility and practicality of this method. This is because the blanket is very resilient, and the two cardboard strips slightly above the surface of the impression cylinder force the partially loosened paper to be tensioned on both sides by embossing. This does not give printing pressure or layout. The registration and ink transfer cause too much adverse effects. Since the author's creation of this method, after the success of the small offset printing test more than 10 years ago, he later tested the wrinkling failure of the J2108B off-color monochrome offset press, and achieved similarly good results, greatly reducing the paper's The phenomenon of waste increases the product's pass rate. This time, our company used the J2205 offset bi-color offset printing press to print carbonless paper. After the first obvious wrinkling failure, the author applied this quick solution to eliminate paper wrinkling and wrinkles, and also achieved a better elimination. Non-carbon paper printing wrinkle failure, the effect is quite satisfactory.