How to deal with carton printing with different materials

Common paper types used for corrugated cardboard paper are box cardboard, liner paper, kraft paperboard, tea board paper, whiteboard paper and single-coated whiteboard paper. Due to the differences in the paper making process and the papermaking process of each base paper, the physicochemical indexes, surface properties, and printability of the above-mentioned base papers are greatly different. In the following, we will discuss the problems brought about by the above-mentioned procedure for the printing of corrugated paperboard inks for the above-mentioned paper products.

First, the problems caused by low-gram base paper

When corrugated cardboard is made of low-gram base paper, the appearance of corrugated marks on the surface of the corrugated paperboard may occur. It is easy to cause blemishes and can not print the required graphic content in the depression of the cymbal. For the unevenness of the surface of the corrugated cardboard caused by the dew, the flexible resin plate with good elasticity should be used as the printing plate to overcome the printing failure. Clear and missing defects. In particular, A-type corrugated board produced from low gram paper, the printing press will make the corrugated board's flat compressive strength is greatly damaged, and after the corrugated board passes the printing roll and embossing roll, the side pressure strength will also be There is more damage.

If the surface of the corrugated cardboard has a large difference in sheet grammage, the corrugated board produced by the corrugated board line may be easily warped. Warp cardboard will cause overprinting and printing groove irregularities in the printing. Therefore, the warped cardboard should be printed after being flattened or reversely flattened at the flap line. If you are forced to print uneven corrugated cardboard easily lead to rules. It also causes the thickness of the corrugated board to decrease.

Second, the original paper surface roughness problems

Printing on rough-surfaced, loose-textured paper has high ink permeability and fast drying of the printing ink, while drying of inks on paper with high surface smoothness and fiber toughness is slow. Therefore, on a rough paper, the amount of ink applied should be increased, and the amount of ink applied should be reduced on a flat surface. Printing ink on paper that is not sized dries quickly, whereas printing ink on sized paper is slow drying, but the print pattern is reproducible. For example, coated whiteboard paper is less ink-absorbing than boxboard and tea board paper, and the ink is slow to dry, and its smoothness is higher than that of cardboard, noodle paper and tea board paper, so the resolution of printing small dots on it is also high. The reproducibility of the pattern is better than that of noodle paper, carton board, and tea board paper.

Third, the original paper to absorb the differences brought about by the problem

Due to the differences in papermaking raw materials and the differences in sizing, calendering, and coating of raw paper, there are differences in the absorption properties. For example, when superimposing on single-sided coated whiteboard paper and kraft cards, the absorption performance is small and the ink drying speed is Slower, so the viscosity of the previous ink should be reduced to increase the viscosity of the rear overprint ink. And put the lines, words, and small patterns on the first color printing, and put the full version on the ground in the last color printing. This can improve the overprint effect, and put the dark color on the front and the light color on the back. Can cover overprinting error, because the dark color coverage is strong, is conducive to overprinting accuracy, and light color coverage is weak, even if there are running rules on the post-printing is not easy to observe.

Different sizing conditions on the surface of the base paper also affect the absorption of the ink. The paper with small sizing amount absorbs ink more, and the paper with large sizing amount absorbs ink less, so the gap of each ink roller should be adjusted according to the sizing state of the paper, that is, the gap of each ink roller should be adjusted to control the printing plate. The amount of ink. From this, it can be seen that when the base paper is introduced into the factory, the absorption performance of the base paper should be inspected, and the printing slotting machine and ink distribution personnel should have a base paper to absorb the performance parameters so that they can dispense ink and adjust the equipment. And for the absorption of different base paper, adjust the ink viscosity and PH value.

Fourth, the problems caused by the difference in surface color of the base paper

The difference in color between cardboard, liner, teaboard, and whiteboard is large. Even if the same batch of whiteboard paper or single-coated whiteboard paper is processed on a corrugated cardboard line, the speed of the production machine differs from that of the whiteboard paper. The whiteness will also change, and there will be a decrease in whiteness or graying and darkening; this will lead to a difference in the whiteness of the same batch of products, and the whiteness of the whiteboard paper printed with the offset press will remain better. Therefore, the corrugated board processed with corrugated board line with white board paper, when printed on a water ink machine, the ink selected is preferably a little deeper than the offset machine, so that the degree of alignment of the printed pattern can be improved, and the color is also bright. In addition; that is the same company using the same species, but different batches of raw paper products, there may be different hue differences, such as the general whiteboard paper whiteness of more than 75%, the whiteness of coated white paper is more than 75%. However, different batches of whiteboard paper will appear some blue, some yellowish. In order to ensure the same color of your own batch of products, you should use the same batch of original paper to print the same batch of products. However, when the number of raw papers in the same batch is not enough, even if different batches of raw papers are to be used, the color difference between the raw papers between the batches and the batches should be considered. The products printed on different batches of base papers should also be marked to distinguish them, so as to ensure The molded product has the same color.

V. Problems caused by the different moisture content of the base paper

The different moisture content of the base paper affects the accuracy of the flatness and size of the corrugated board. Therefore, when corrugated board is produced on a corrugated cardboard line, the envelope area of ​​the base paper on each preheater and the production speed of the cardboard line are adjusted according to the moisture content of the base paper, and it is preferable to control the moisture content of the corrugated cardboard produced. 9%, in order to ensure that the corrugated board produced is smooth, the corrugated board is hard and strong, otherwise, the strength of the corrugated board will be greatly damaged after the printing slot machine. However, when the corrugated board is too dry and the upper printing press passes through the paper-guiding roller and the reel press line, it is easy to crush the inner paper, so the moisture content of the corrugated board should be strictly controlled.

Sixth, ink printing printing slotting machine debugging problems

When using low-gram paper, when making corrugated cardboard and carton paper, if the gap between the feed rollers is adjusted too small, the corrugations will be bruised. When the paper is low in crotch, the clearance between the pinch rollers is too small and it is particularly easy to crush the paper.

When the pattern is printed near the indentation line, the indentation can be changed to the dark line (in the slitter automatic line slitter or on a single-segmentation line press; only the indentation of the paper in the carton is suppressed. Lines do not suppress the indentation line of the box.)

Seven, the paper filler and sand damage to the tool so that the problem of unhappy tools

Corrugated cardboard before cutting through a variety of tools, in order to ensure that the edge of the cutting edge of corrugated cardboard smooth, no glitches, reduce paper gray, paper debris, impurities by the ink stuck to the printing plate and block the plate, resulting in the printed The product does not meet the requirements. As a result, various tools for processing corrugated board are required. In particular, corrugated board produced from ordinary boxboard and low-grade teaboard paper is prone to produce paper dust, paper dust and impurities. Therefore, tools that require corrugated board are not subject to sharp edges and notches. They should be sharpened or replaced regularly. Tool. In addition, the sand and hard fillers in the base paper are very severe in damage to the cutters. Therefore, when the base paper is introduced into the factory, it should be strictly controlled. The base paper with more sand particles should not be added to the factory.

Eight, different paper materials and papermaking process to bring the problem of printing

For example, the penetrating ability of the ink on the kraft paperboard is slower than that of the cardboard board, and the absorption of the ink on the coated paper is less than that of the cardboard board and the tea board paper. The amount of ink sucked on the liner paper is between kraft paper and tea board paper. The surface strength of tea board paper is easy to lose the hair and make paper gray. Therefore, it is better to use the ink with small viscosity, which can reduce the paste plate. In addition, when cardboard and tea board paper are used as carton paper, the absorption performance of box paperboard and tea board paper is relatively large, and the viscosity of the ink and ink can be properly reduced to reduce the problem of falling powder. However, if the paper absorbs too much raw paper, there will be another problem that causes the printed color to fade and become less bright.

Nine, the choice of printing

The thickness of the printing plate is preferably selected according to the surface roughness and different thicknesses of the corrugated cardboard. If a fine picture of a photo type is printed on a corrugated cardboard box, it is preferable to use a coated white paper and print it on the offset printing machine with the PS plate. Better natural color reproduction. In the rough surface of the kraft paperboard, noodle paper, cardboard box, tea board paper printing, should be used thicker and better elasticity, strong wear resistance of flexible resin plate. For thin lines, small texts, and small patterns, a harder rubber plate can be used, but the thickness of the printing plate must be ensured, and the pressure can be appropriately increased during printing to achieve the purpose of clearly printing the printed content onto corrugated paper. Printed version of the plate used in the field should use a flexible resin plate with low hardness and good elasticity.

The printing plate is stuck on the polyester film to be firm, otherwise the ink will be soaked to the place where the double-sided tape is attached to cause the printing plate to pop open. When the printing plate is in the state of high speed, the product that will be crashed or printed will not appear. Wild ink should be there.

Ten, select from the process

When printing multi-colored ink, it is necessary to pay attention to the viscosity of the ink after printing. Otherwise, the multi-colored ink will not be printed on the ink of the previous color, but the hair color and the background color will appear. In addition, it should be noted that the ink contains alcohol and amine volatile solvents. Therefore, for a long time when the printer is stopped, the ink roller of the printing machine should always be in operation to prevent the ink on the ink roller from thickening and sticking.

Printing to avoid thermal printing corrugated board, thermal corrugated cardboard due to its cardboard fiber under the thermal effect of soft, the corrugated shape has not yet fully stereotyped, so be sure not to print thermal corrugated cardboard, or the corrugated board will be the edge of the pressure strength damage Larger and severer, the edge pressure of corrugated board will drop by more than 20%, and it will also cause the loss of thickness of corrugated board. So it is best not to print thermal corrugated cardboard.

Source: China Packaging