Transfer paper seam avoidance technology in cigarette pack printing

The meaning of seam avoidance

Although most cigarette pack printing companies now use leaflet printing methods, with the deepening of mergers and reorganizations in the tobacco industry, cigarette pack printing companies must face the reality that cigarette pack order brands are gradually decreasing and orders are gradually increasing, in order to satisfy each The need for large-scale cigarette factory large-scale production, the use of rotary printing is imperative. Due to the rainbow laser transfer paper in the production process, inevitably there is a joint problem, which brings a large amount of waste products to the printing production, especially rotary printing. How to print the required printing pattern on the non-seam position in rotary gravure printing and flexographic printing to reduce waste and reduce consumption is a major problem in the printing industry at home and abroad. Printing companies generally do not make joint avoidance, but this practice has the following problems.

(1) The high rate of printing waste products increases the production cost. Calculated by 2 × 6 imposition method, due to rainbow laser transfer paper joints caused by the printing waste rate of not less than 17%.
(2) 17% of the printed products with seams in the printed die-cutting product must be subject to 100% manual inspection, and the waste products should be detected. This requires a lot of manpower, and the production efficiency is low, so it is difficult to guarantee the products of each roll. Can meet the requirements of the tobacco factory.

Joint avoidance solution

After more than one year of experiments, we have developed a complete rotary print seam avoidance technology program. The implementation of this program can avoid 100% rainbow laser transfer paper joints, reduce printing consumption, improve production efficiency, and meet the major cigarette factories. The demand provided a correct method for rainbow laser transfer paper rotary printing for cigarette pack printing plants.

The basic principle of the scheme is to keep the length of the printing plate and the repeat length of the seam consistent, so that the seam is printed at the non-patterned position, and rejects are removed when cutting to achieve the purpose of avoiding seams (as shown in Figure 1). The key to this solution is how to keep the printing repeat length and the repeat length of the seam consistent. In the rotary printing, keeping the printing tension relatively stable can ensure that the printing repeat length is consistent; and adopting a high-precision servo control technology to strictly control the rainbow laser transfer film and compounding Seam repeat length changes during transfer.

In order to solve the technical problems of the joints of rainbow laser transfer paper, we combined the multiple transfer technology and rotary printing technology to summarize the printing practice for many years. After many analyses and experiments, the following solutions were summarized.

(1) Adopting advanced high-precision stretching technology and register technology, the compound peels out the joint and repeats the length-stabilized rainbow laser transfer paper (has applied for a national patent).
(2) Rainbow laser transfer film is PET material, and there is instability in the process of compound drawing. We have pioneered the method of pre-printing the registration cursor on the rainbow laser transfer paper to ensure the stability of the subsequent printing register (requested National Patent).
(3) Revamp the rotary printing production line and increase the high-precision seam avoidance feed mechanism. The basic principle (as shown in FIG. 2) is that a set of paper feeding control mechanism is added between the unwinding mechanism of the rotary printing press and the first printing color group. This mechanism drives the servo motor to print according to the information obtained by the photoelectric head. The amount of paper feed is controlled.
(4) Revamp the unwinding device and increase the positioning and splicing system. The basic principle of positioning and pulling is to add a photoelectric system to the unwinding mechanism, to scan the seams of the paper, to command and control the splicing system, to realize the positioning and splicing of the working paper roll and the ready-to-roll paper, and to meet the rotary printing machine. Continuous printing without stopping. Its working principle is shown in Figure 3.

By adopting the above technologies, rainbow laser transfer paper seam avoidance is achieved, and the process scheme thereof is shown in FIG. 4 . Through more than one year of implementation, we have accumulated rich experience and have applied rainbow laser transfer paper produced by Yunnan Dexin Paper in France Komori Shangbang GR650 gravure printing machine, Swiss BOBST830 gravure printing machine, and Jarus flexo printing machine Successfully achieved the rainbow laser transfer paper seam avoidance on the rotary machine.

Reprinted from: Ke Yin Network