Carton paper printing failure and break (1)

At present, small and medium-sized packaging containers, such as beer cartons, beverages, fruit and other food cartons, are more and more products that use white paper for color printing. This is a commodity economy development trend. The preprinting process of the carton is greatly improved over the quality of the direct printing using corrugated cardboard, and the cutting plane printing structure and the printing adaptability are also broader. However, as with other printing processes, the use of offset presses or letterpress printers to print a variety of cartoned paper or carton, paper tape products, but also inevitably encounter some problems, affect the quality of the product printing. Therefore, correct understanding and understanding of some of the fault phenomena in the printing process, and the good printing operation and process technology, in order to better improve production efficiency and product quality.

Imprinting caused by uncomfortable printing pressure

When there is a serious situation in the wear of the periphery of the blanket cylinder, one situation is due to the excessive roll release, which causes the surface of the cylinder to slide and rub and cause the marking of the ink stick to appear; in the second case, due to the use of a hard liner, the pressure If the printing is too large, the backlash of the gear is too large, so that the gears vibrate after the roller is pressed, and the sliding friction occurs on the surface of the roller to cause ink bars. The third case is the pressure between the plate cylinder and the blanket cylinder. Too large, so that the blanket is squeezed to form a larger friction and sliding, so that the layout of the screen to expand the vertical deformation and cause ink bars. The above situation should be replaced by roller bearings; adjust the characteristics of the package liner; reduce the center distance of the roller, so that the gear backlash is less than 0.1mm; according to the specifications of the equipment, set the padding

Dirty teeth due to roller overprinting failure

When the tooth surface of the roller crushes is worn, deformed, and the teeth are insufficient and uneven, the slippage of the printed sheet is likely to occur in the embossing after entering the clenching, and the overprinting of the product is not caused: the crotch, especially the ink receiving area of ​​the printing plate surface, the ink When the viscosity is large, overprinting is more likely to occur. In this regard, the solution is to remove the severely worn teeth and replace them with new ones. The teeth will be unevenly pressed and the teeth will be insufficiently adjusted so that the entire tooth surface will be tightly pressed against the edge of the paper; Too large, moderate dilution adjustment with additives to reduce the viscosity of the ink; for printing spot color inks, the ink hue can be appropriately deepened to make the printing ink layer thinner, which can reduce the viscosity of the ink, Meet the printing hue requirements. In addition, the printing pressure can be appropriately reduced to prevent overprinting of the printed sheet due to slippage during imprinting.

Excessive printing pressure caused by the dirty version and paste phenomenon

When the pressure of offset printing is too high, the frictional force of the blanket facing the surface of the printing plate must increase, so that the surface of the plateau is damaged by abrasion, the hydrophilicity of the blank area mutates, and the ink is easily adhered and transferred to the printing product. This is a dirty version. In addition, the printing pressure is too large, the expansion and contraction deformation value of the blanket is also large when pressed, and the transfer of the imprint is also likely to cause deformation. In particular, printed dots and small texts often appear to be illegible. If it is the letterpress printing process, the performance of the fine negative line and the negative type layout is even more pronounced. Therefore, to prevent the occurrence of dirty plates and stencils, it is necessary to accurately adjust the printing pressure. It is necessary to control the thickness of the pad and the center distance of the rollers according to the specifications of the equipment.

Ghost failure due to printing pressure

When the pressure between the blanket cylinder and the embossing cylinder is too large, the amount of deformation of the blanket increases accordingly, so that the ink layer cannot be restored after transfer in the imprinting process, so that when receiving the imprint from the plate cylinder, , it is easy to produce a small amount of difference, resulting in ghosting. In this regard, it is appropriate to reduce the pressure of the roller and reduce the expansion and contraction coefficient of the blanket during imprinting to prevent ghosting failure. In addition, for the use of aging blankets, should be replaced with a new blanket for printing to eliminate print ghosting failures.

Inflation of ink caused by uncomfortable printing pressure

When the liner is uneven, uneven pressure or insufficient imprinting, poor contact may occur between the plate and the rubber, between the blanket roller and the embossing cylinder, or between the plate and the pad (the relief process), and affect the layout ink layer. Uniform and full transfer, which is easy to cause the lack of pressure on the layout of pale ink, hair phenomenon. In order to avoid this unfavorable situation, it is necessary to turn off the printing technology of "Sanping", and to protect the surface of the embossing roller to prevent it from losing its flatness due to damage and deformation, and to maintain uniform and sufficient printing pressure. Efficient measures to eliminate printed hair color.

(to be continued)