Improve the printing quality of the carton, need to pay attention to these
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Guaranteed print definition
First, the printing plate should be made of materials that are wear-resistant, moderately elastic, and of high quality. The thickness of the same plate should be the same, the thickness of the resin plate should be no less than 4mm, and the rubber plate should be 6mm to 7mm. No matter if it is used for drying film or laser engraving, the layout must be neat. The depth of text, pattern and lines should not be less than 3mm. The arrangement of text patterns should not be overcrowded. The arc should be sleek, 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 is moderate, so that the printing ink is even and the surface of the ink box has no obvious dent. 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 results in the paste of the printing area, and the printing quality is even worse. In particular, the characters are small, the pattern is complex, the lines are delicate, and the printing requirements are With high-precision layout, the disadvantages are even more pronounced; the speed of the printing press can't be lower than 800r/min, the ink on the surface of the box is too uneven, and there is a phenomenon of exposed bottom. Too fast ink is too thick, the layout is easy to blur, 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 stop immediately, wipe with a rag and dip in alcohol.
Printing color should be pure, batch colorless
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 and viscous. The concentration is suitable for adding water or alcohol solvent to dilute without precipitation and agglomeration. Stirring with a wooden stick produces no foam. It is mixed with other inks and has good affinity and compatibility. Solubility, pure ink, no abnormal reaction. On the contrary, it cannot be used.
It is best to print in batches at once, otherwise color differences will occur even if the same ink is used. 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.
Prevent overprinting and ghosting in coated whiteboard carton printing
When the coated white paper is manufactured, the coating liquid for coating the white board contains a certain amount of glue, and the surface of the high-grade white paper is coated with a small amount of gloss wax, so when the paper box with the white board is used for printing, the printing plate There is slippage at the moment of contact with the whiteboard paper. 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, ink should be lightened with ethanol, do not use water, because it is not volatile, is not conducive to the drying of ink; printing pressure is properly reduced, the printing speed should not be too fast, not more than 600r/min is appropriate. Before the stacking of printing presses, an exhaust fan or hot air drying box ink is installed.
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 drawn, draw a long-width high-height line with a small stroke, and press the sample or sample box. Production notices stipulate imposition. After positioning the layout, use the pen to draw the line on the edge of the printing plate. After that, the same size plate base prepared in advance is overlaid on the base plate of the well-drawn line, and all edges are accurately traced (for example, three colors can be used to overprint a plate base). ), Finally, press the printing color, and 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 center line of the printing plate can be aligned with the centerline of the platen roller of the printing machine. As long as the position of the imposition is accurate and other objective conditions are satisfied, overprinting is accurate.
Influence of full-version printing on carton strength
We know that during the carton printing, the corrugated cardboard is formed by the paper guide rollers and printing rollers of the printing machine and transferred to the grooved portion. After the paperboard is pressed by the roller during the transfer process, the physical properties of the paperboard are changed by different procedures. Affect the strength of the carton. This is particularly noticeable in full-screen printing. Compared to non-printed cartons, the strength of the carton of the same material is reduced by about 30%. Therefore, the production process must be paid attention to and can be mitigated by the following measures:
1.Adjust the gaps of the paper guide rollers of the printing press properly so as to make the corrugated paperboard pass smoothly without deformation (slightly smaller than the best paperboard thickness 0.1mm~0.15mm);
2. The plate pressure adjustment can meet the need of printing clearly, and the surface of the box can be handled without depression and leveling. Thirdly, the speed of the printing machine (1000 r/min or more) is properly increased, so that the cardboard can pass through the printing machine as soon as possible to reduce the pressure time of the cardboard. .
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 only the notch is cut, the slotted knife can be removed, or the slotted part can be removed, the missing layout can be subsidized to the corresponding position, and then the other steamed plates can be opened and reprinted, but it is forbidden. The speed is too fast, otherwise the printing effect is not good or the layout moves. If the printed carton has been nailed, in addition to dealing with the layout in accordance with the above method, but also adjust the gap between the guide roller to the shape of the carton after the smooth deformation is not appropriate, the printing roller pressure must be adjusted, and then transfer the paper Baffle, determine layout position, single delivery when printing.
Thin cardboard printing notes
The so-called thin cardboard, that is, D, E 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 the production Use print slotting instead. 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 sides of the carton, different loading plates must be printed twice to complete a complete layout of the carton.
Warping cardboard to prevent running, slotting
The warped cardboard printing adopts single sheet feeding, low-speed operation, and appropriate adjustment of the amount of suction, according to the layout of the layout, slotting in time to move the printing plate groove phase forward and backward correction. Warp severely selected cardboard, every 3 to 5 positive and negative stacking with the weight of flattening reprint next time, or folded along the indentation line to the opposite direction of warping folded again.