Carton ink printing quality control experience

As we all know, the key factors affecting product quality are equipment, raw materials, personnel and the environment. Carton packaging companies do the same. Here only a brief description of the experience of improving carton quality from the point of view of ink printing.

First, ensure the clarity of printing

First, the printing plate should be made of wear-resistant, moderately elastic, high-quality materials. The thickness of the same plate should be the same, the thickness of the resin plate should not be less than 4mm, and the rubber plate should be 6-7mm. Regardless of whether it is using negative film printing or handmade knife engraving, the layout must be flat. The depth of the lines of the writing pattern should not be less than 3mm. The arrangement of the text patterns should not be overcrowded. The arc should be smooth, uniform in thickness, and straight and smooth. When printing, the ink should be properly lightened, the ink layer of the ink coating roller should not be too thick, and the pressure of the roller should be moderate, so that the printing ink is evenly distributed, and no obvious dents on the box surface are preferred. Do not increase the ink concentration, increase the pressure of the ink roller to improve the printing effect. This not only fails to achieve the ideal purpose, but also results in layout paste, printing quality is worse, in particular, the text is small, the pattern is complex, the lines are delicate, and the printing requirements are accurate. With the high layout, the disadvantages are even more pronounced; the speed of the printing press can't be lower than 800 rpm, the speed is too slow and the ink in the box is uneven, and there is a phenomenon of exposed bottom. Too fast ink is too thick, the layout is easy to paste, but also to prevent paper hair, paper scraps, etc. into the printing press stick to the printing plate, if there is a piece of paper glue sticking, to immediately stop, wipe with a rag and rubbing clean.

Second, the printing color should be pure, no color difference

The pros and cons of water-based inks are the key to the pure and bright color of carton printing. Therefore, great care must be taken in the selection. There is no significant difference between high-quality inks and color marks. The touch is delicate, thick, and the concentration is suitable to add water or alcohol solvent to dilute without precipitation and agglomeration phenomenon. Stir with a wooden stick and produce no foam. Mix with other inks, and the affinity is good. Dissolve the phenomenon, the ink color is pure, there is no abnormal reflection, on the contrary can not be used.

When printing, it is best to print once in batches. Otherwise, even if the same ink is used, there will be color differences. The reason is that the original ink is diluted with water or an alcohol solvent and is not sealed. When it is exposed to the air for a long time, the chemical components in the ink react with the oxygen in the air, that is, the pigment is reduced, and the strong light can also decompose the ink.

Third, to prevent the overprinting and ghosting of coated whiteboard carton printing

When the coated white paper is manufactured, the coating liquid used for coating the white board contains glue, and the surface of the high-grade white board is coated with a small amount of light wax. Therefore, when the paper box is used as a paper board for white paper, the printing plate comes into contact with the white paper. There is a slippery phenomenon in the moment. In addition, the pressure of the printing plate is too heavy, the water-based ink is not easy to infiltrate, and the printed carton ink is dried slowly. The printing job is continuous, and the printing products are stacked one on top of the other.

To solve this problem, the ink should be lightened with ethanol, do not use water, because it is not volatile, unfavorable ink drying; printing pressure should be reduced appropriately, the printing speed should not be too fast, not more than 600 rev / min is appropriate. Before the stacking of printing presses, an exhaust fan or hot air drying box ink is installed.

Fourth, ensure overprint accuracy

The overlay accuracy depends first of all on the precision of the equipment and the adjustment of the feeding section to push the paperboard in parallel. In addition, it is the layout production, assembly and correction. The following is a discussion of overprint accuracy in terms of layout collage.
After the plate is ready, take a piece of 0.5mm thick transparent polypropylene plate, draw a vertical line at the center of its length, and then press the size of the carton to be printed, draw a line with a small stroke to draw the length, height and height of the line, and press the sample or sample box. Production notices stipulate imposition. After positioning the layout, use the stylus to draw lines along the edge of the printing plate. Then cover the pre-prepared plate of the same size on the base plate of the drawing line and accurately trace all the edges (for example, three colors can be used to overprint a printing plate). In the end, press the printing ink to make sure that the corresponding printing plate is firmly stuck in the painted position with neoprene. Then use the double-sided adhesive to attach the printing plate to the roller of the printing machine. The middle line of the printing plate can be aligned with the centerline of the platen of the printing press. As long as the position of the imposition is accurate and other objective conditions are satisfied, overprinting is accurate.

Fifth, the effect of full version printing on carton strength

We know that when printing, corrugated board is passed through the paper guide rollers and printing rollers to the slotted section of the printing machine. After the board is pressed by the roller during the transfer process, the physical shape of the board changes to varying degrees, which will inevitably affect The strength of the carton. Full-plate printing is particularly prominent. Compared with no-printing, the cardboard box of the same material has to be reduced in strength by about 30%. Therefore, it is necessary to pay great attention to the production process. The following measures can be taken to ease it:

First, properly adjust the gaps of the paper guide rollers of the printing press so that the printing paperboard can pass through inconvenient actions (slightly smaller than the thickness of the paperboard 0.1-0.15mm);

Second, the pressure of the printing plate can be adjusted to meet the requirement of clear printing.

Thirdly, the speed of the printing press should be properly increased (above 1000 revolutions/min) so that the paperboard can pass through the printing press as soon as possible to reduce the time for the paperboard to withstand pressure.

Sixth, carton leakage version timely reprint

The actual production of a printing machine without a computer stencil printing device is difficult to avoid due to operator's negligence. After similar things happen, remedial measures should be taken promptly. If you only slot and cut corners, you can unload the slotted knife, subsidize the missed layout to the corresponding position, and then you can reprint the other layouts to start the reprint, but avoid the speed too fast, otherwise the effect of overprinting Poor or layout moves. If the printed carton has been nailed, in addition to the above layout processing, it is also necessary to adjust the gap between the guide rollers to the shape of the carton after the smooth passage without deformation is appropriate, the printing roller pressure should be adjusted properly, and then transfer the paper section file Plate, determine layout position, single delivery when printing.

Seven, thin cardboard printing matters needing attention

The so-called thin cardboard, that is, D, E and other fine corrugated cardboard, these thin cardboard after the printing of the application of flat pressure die-cutting machine stamping, due to small quantities or customers only once, coupled with the high cost of die-cutting knife, so when production Instead, use printing slotting. In actual operation, because the paperboard is too thin, the printing speed must be slowed down, but the paper feeding device is not difficult to push paper, that is to push multiple paperboards at the same time into the printing press, resulting in a lot of waste. To solve this problem, you can use a single machine to slot, then print after binding and forming, but according to the two positive side of the carton, different types of plates must be printed twice to complete a complete layout of the carton.

Eight, warpage cardboard to prevent running board, slotted go

The warped cardboard printing adopts single sheet feeding, low-speed operation, and appropriate adjustment of the amount of suction, adjusting the slot position of the printing product in time according to the layout and slotting, and correcting it in reverse. The cardboard with serious warpage is selected, and the 3-5 sheets of positive and negative stacking are flattened and reprinted with the weights next time, or folded back along the indentation line to the warpage.

In short, in actual production, under specific circumstances, we must also be flexible in dealing with objective conditions. The above is for reference only, because the author's level is certainly limited, and is willing to discuss with peers.

Source: Shaanxi Beiren Printing Machinery Co., Ltd.