Corrugated paper pre-printing processing methods and their disadvantages

The printing of corrugated packaging can be divided into two printing modes according to different processing procedures. One is traditional post-printing, also known as post-printing, that is, printing directly on processed corrugated cardboard. In this type of printing mode, flexographic printing presses were used for printing. In the past, some internationally renowned printing press manufacturers, such as Man Roland and KBA, have also developed offset presses that can be directly printed on corrugated cardboard. Making the quality of packaging printing greatly improved, another model is preprinting.

According to the processing method, preprinting can also be divided into two types, namely, preprinting of flat paper and preprinting of web. Flat paper preprinting is to make corrugated cardboard without face paper, while printing offset paper with an offset Printing Machine, and then using a paper crepe machine to paste the facial paper on faceless corrugated cardboard. Web preprinting is the use of flexo printing or gravure printing. The packaging pattern is pre-printed on the web to be processed. After that, it is directly used as face paper for the processing of corrugated paper. In this way, the processed is Corrugated cardboard with the desired pattern.

At present, post printing is the dominant position in the printing of corrugated paper in China, and flexographic printing takes the absolute leading market share in the post-printing model. In fact, there are serious drawbacks to this type of printing :

1. Damaged corrugated cardboard, which affects the compressive strength of the carton;

2. The effect of ink erosion affects the stacking strength of the carton;

3. Dot expansion, pattern distortion, image distortion;

4. Affected by the flatness of the substrate;

5. The adjustment of printing pressure is difficult to grasp and the number of times of printing is poor.

Compared with post-printing, the advantages of pre-printing are mainly reflected in five aspects:

1. Does not damage corrugated cardboard, does not affect the compressive strength of the carton;

2. Substrate flatness is significantly better than corrugated cardboard;

3. The thickness of the substrate is uniform, so the printing pressure is easy to adjust;

4. The pattern distortion is very small, the level is clear, and the printing quality is very high;

5. High labor efficiency and high productivity.

The advantage of the pre-printing process of flat paper is to use lithographic offset printing, exquisite printing, colorful, and strong performance. However, this processing method also has some deficiencies

1. The increase in the number of processes leads to an increase in the probability of rejects, and at the same time, it also reduces labor efficiency and productivity.

2. It is easy to wrinkle after covering, forming a "washboard";

3. Because of the different time between the paper and the paper, the paper board will warp because of uneven water, which will affect the die-cutting and carton compressive strength of the carton;

4. The high cost is only suitable for products with high added value, and the market is narrow.

The main disadvantage of the web preprinting process is that this method is only suitable for large batch processing of a single type. In addition, when the preprinted tissue paper passes through the corrugated cardboard assembly line, it is susceptible to thermal and frictional problems such as blemishes and high-temperature oxidative decolorization. Because it is difficult to change the heating and corrugated board lamination process, and the existing inks and inks have drawbacks, it is difficult to completely solve this problem.

At present, the common practice for the protection of imprinting is to add BOPP film. After printing, cross-cutting, cold-cladding, and coating are used. Among them, the use of imported temperature-resistant varnishes has a good effect and high efficiency, but the cost will be greatly increased. Therefore, the protection of imprinting has become a bottleneck restricting the development of preprints. In the past, gravure printing machines were generally used for web preprinting. However, with the continuous development of flexographic printing technology, Flexo will occupy a larger market share after solving the problem of high temperature and abrasion resistance of imprints.