Corrugated box printing, at the beginning of the main use of offset printing. In recent years, with the development of water-based ink, flexo letterpress has gradually replaced offset printing and become the mainstream. Water-based flexographic ink generally used water-soluble acrylic resin as the binder, water as the main solvent, in line with the new trend of green environmental protection. In this paper, the carton printing process of a number of problems to make a discussion for carton printing enterprises reference.
1, Lack of Printing
Corrugated board surface smoothness is the main factor affecting the printing, such as a corrugated board because of corrugated type, corrugated spacing, especially easy to cause surface wrinkle, in the use of low-weight paper is particularly prone to percolation, affecting the printing; B corrugated box relatively better. In this regard, on the one hand, should strengthen the management of the plate to avoid additional creases; on the other hand, can be slightly adjusted on the printer. Properly reducing the space between the plate cylinder and the pressure cylinder (that is, increase the plate pressure) can eliminate the leak, but to prevent the corrugated cardboard was crushed. In addition, for large-area printing plate, you can use double-sided adhesive properly pad the middle part of the printing plate, you can also eliminate gaps.
2, Out-of-column white space
When the impressing roller and print cylinder or pressure between print cylinder and impressing roller is too high, the printing ink will be pressed out of the surrounding area of the printing ink concentration is thin, and the printing plate around will overflow very thick ink, in this case transferred to the cardboard surface, overflow in the printing plate around the ink as if the frame, the dot will be pressed to disappear. We call this the out-of-column white space.
To prevent the column blank, then
To maintain the pattern wheel, plate cylinder, cylinder kiss each other as the degree of pressure between the three, one of the pressure is too high will occur when the ink overflow edge of the situation, this adaptive pressure is best adjusted to a slight kiss.
If the plate thickness is uneven, you can properly grinding the plate, or in the plate back sticker, etc. .
If more broadside printing, need to use more hard ink, coating amount to a bit more, printing pressure is also a bit heavy; fine print or dot printing more, the use of better liquidity of ink, coating amount not too much, the impression should be adjusted to the minimum.
3, Overlapping white
When in one color on the cover of another color (usually black) , often appear on the second color printing can not be printed. The reasons can be attributed to two kinds:
ink pigment surface tension difference is large, The above ink pigment can not be evenly covered in the following ink layer. At present, there is no way to solve this problem completely. In the practical operation of corrugated carton box printing, the following methods can be slightly improved:
(1)To increase the drying speed of the first color, such as adding alcohol or ammonia,
(2)To reduce the viscosity of the second color, or to improve its adhesion, increase printing pressure appropriately.
4, Viscosity increase
In the use of the process, ink often appear viscosity increase, color deepening, which is due to the ink caused by ammonia volatilization. Viscosity and PH value, with the ink constantly cycle, ammonia volatilization, PH drop, increased viscosity; at the same time water volatilization, so that printing color deepening. Therefore, in the printing process (especially in the sealing sample) , should control the ink viscosity, appropriate point of water to ensure consistency before and after the hue.
5, Ink waste control
In the carton printing workshop, scrap ink has been a big problem, often a variety of three or four half a barrel of ink situation. There are two reasons for this: first, ink workers like to use the original barrel of ink, which can reduce the color deviation and other troubles; second, the half barrel of ink used can not be returned in time. In fact, the solution is very simple, on the one hand, to strengthen the supervision of the warehouse, there must be half a bucket of ink, as for the remaining ink due to the water caused by color deviation can be solved by adding proper ink; On the other hand, you can also use all the remaining ink to adjust the ink, which needs to adjust ink workers have enough experience.
6. Special ink and ink mixing
Currently, small carton box factories generally do not have professional ink mixing workers. They do not mix their own colors. All the required ink is purchased directly from the ink factory. This saves trouble and ensures quality, but it costs more. Ink factory if the supply is not timely will cause material. On the scale of the carton factory are equipped with professional inking personnel, small batches of special ink by their own transfer (the ink from the ink factory to buy) , so that you can transfer cash, to ensure supply, and prices are lower, because of the current ink manufacturers base ink and ink between the price difference. Only a large number of spot-color ink from the ink factory orders. From an economic point of view, the carton factory can save a lot of money by buying all the base ink to adjust, but it must ensure two things: first, the ink mixing staff is skilled and well-staffed; second, it needs to be equipped with a certain amount of ink mixing equipment, including mixing device and ink cylinder, otherwise a small bucket of ink scraping a sample is not realistic.
