Analysis of corrugated board printing process
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With the advancement of society, economic prosperity, increasingly fierce market competition and the continuous improvement of people's living standards, people's requirements for commodity packaging are also increasing. The packaging of goods, whether it is directly facing the inner packaging of the consumer or the middle packaging and outer packaging that may be discarded during the transportation and storage of the product, plays a vital role in the promotion of the product and the creation of the brand. The role of corrugated boxes, which were originally used as product packaging for protection of products, has been continuously enriched, which has directly led to an increase in the quality requirements for corrugated box printing, which has led to the diversification of corrugated board printing methods.
First, corrugated board printing process
At present, the printing of corrugated board is mainly based on flexographic printing. In China, it accounts for more than 70% of corrugated board printing, and in Europe and America it is more than 85%. The printing process can be mainly divided into two categories: one is the direct printing process, which is to directly print on the corrugated cardboard that has been formed; the other is the pre-printing process, which is to print the corrugated paper first and then print the surface. The paper is combined with corrugated paper to form corrugated cardboard.
1. Direct printing process
The direct printing process is one of the main printing processes for corrugated board. The direct printing method mainly includes two types, flexographic printing and offset printing, in which flexographic printing is absolutely dominant. The process of the direct flexographic printing process is as follows: corrugated cardboard is produced by directly printing a film cutting slot and a bonding nail box. Direct offset printing is mainly used for the printing of micro corrugated cardboard. The process flow is: micro corrugated cardboard production, a micro-cardboard direct offset printing, a film cutting slot and a bonding nail box.
(1). Flexographic printing is the use of flexible plates. A printing technique that uses a water-based ink or a solvent-based volatile ink to transfer ink through an anilox roller. Flexographic printing has the characteristics of quick drying of ink, high printing speed and low cost, and is especially suitable for printing corrugated cardboard which does not require high printing precision. Flexographic printing corrugated board has the following characteristics:
(2). Replace the past with water-based quick-drying inks
A new EPN process that has emerged in the field of packaging. It is also an innovation in the offset printing process. However, due to the large printing pressure of the offset printing and the use of dampening solution in the printing, the pressure and the water absorption will reduce the strength of the corrugated cardboard. Therefore, at present, direct offset printing can only be printed on micro corrugated cardboard with high strength and ultra-thin, and a special blanket with strong compressibility and good ink absorption transfer performance is used to prevent the strength of the corrugated cardboard from falling and the washboard. "The emergence of phenomena.
In addition to the above two main EPN methods, the direct printing method of corrugated board is also screen printing. Screen printing printing can be large or small, easy to plate, low printing cost and thick printing ink, high color saturation. The visual effect is strong, but the resolution is not high, the image accuracy is low, and it is not suitable for the linkage production line. The production efficiency is low, so the direct printing of corrugated cardboard is only suitable for the production of corrugated cardboard by a single machine and is used when the batch is small.
2. Preprinting process
Flexographic printing, which dominates direct printing, has many advantages. But there are still many difficulties in printing patterns that are comparable to offset and gravure. In order to get beautifully printed corrugated cardboard. Many manufacturers use a pre-printing process. The process of the pre-printing process is: pre-printed paper and corrugated composite bonding produced by the production line, a computer slitting, a computer cross-cutting, a film cutting slot, and a bonding nail box. Corrugated board preprinting can be printed in a variety of ways, including offset preprinting, gravure preprinting, and flexo preprinting.
(1) Offset printing is to first print the corrugated box surface paper with offset printing, and then use the single machine to reclaim the corrugated board. The process flow is: offset printing single sheet and single-sided machine roll single-sided corrugated cardboard laminating machine The die-cutting slot is a bonding nail box.
Offset pre-printing can obtain beautifully designed cartons, but it also creates other problems, such as complicated process, high production cost, long production cycle, low carton strength, limited printing materials, limited printing format, high carton rejection rate, and production site. Large, high labor intensity, especially for large-volume packaging carton printing. Due to the high production cost and long cycle, the customer's demand for products cannot be kept up. From the development trend of foreign packaging industry, the offset printing method will be gradually reduced in the production of corrugated board.
(2) Gravure preprinting is a pre-printing technique in a wide roll
Pre-printed the desired delicate pattern on paper (carton paper). 2. Then, the corrugated cardboard production line on the roll-shaped printed paper is made into corrugated cardboard. Then die-cutting the indentation into a box type with a die-cutting machine. The features of gravure preprinting are:
1 Print quality is best and most stable in all printing methods.
2 using water-based ink. Green.
3 printing plate with high printing resistance. Suitable for high-volume printing production of cartons.
4 Suitable for printing continuous patterns.
5 printing speed is fast. high productivity.
6 plate making is complicated. And the plate price is higher. It is 8 to 10 times that of flexo.
7 Process technology is more complicated, relatively more processes, and high printing costs.
(3) Flexo preprinting uses a flexographic printing press to print on a web. After printing, it is still received as a web. 4. The printed web is then made into corrugated cardboard box as a corrugated board production line on the carton paper. Then die-cutting the indentation into a box type with a die-cutting machine. The features of flexo preprinting are:
1 Non-toxic and non-polluting, it is conducive to protecting the environment. It is a green and environmentally friendly printing method, which has great advantages in the printing of green cartons such as food boxes and medicine boxes.
2 Large-format, multi-color, high-quality color crates can be printed.
3 A wide range of printing materials, can bear EO30-700g/m2 paper and cardboard.
4 Printing with different network lines, fine print patterns and good print consistency.
5 Re-bonding the face paper and corrugation on the corrugated board production line can improve and improve the strength and stamping strength of the corrugated board.
6 Printing costs are low, speed is high, and output is high.
7 High-light and dark-tone dots are easy to lose, suitable for copying from 8% to 85% tonal regions.
8 You cannot copy too small text lines. Since the flexographic plate is deformed during printing, the small characters and lines are enlarged and pasted.
Second, the comparison between direct printing process and pre-printing process
Although direct printing is still one of the main printing processes in corrugated board printing at home and abroad, it is simple in process. In addition to the advantages of high speed and short cycle, other aspects are not as good as the pre-printing process. Compared with the direct printing process, the pre-printing process has some obvious advantages: First, it can obtain higher printing quality and is more adaptable. Second, pre-printing can carry out more rich printing. Printing quality is also more stable and reliable. The third is to make the corrugated box get higher strength. This is because pre-printing does not emboss the cardboard after it has been formed. Can avoid corrugated deformation and weaken the strength of the board. When using direct printing. Because each color printing will make the corrugated board more or less deformed. And the more the number of day colors. The greater the effect on the deformation of corrugated board. therefore. Pre-printing has become an important development trend in corrugated board printing. Especially high-grade delicate carton. Large and heavy cartons are more suitable for pre-printing.
In short. There are many ways to print corrugated cardboard. And in order to meet the requirements of various packaging. Its printing method will continue to increase. And these printing methods have their own advantages and disadvantages. Suitable for different requirements and uses. As a manufacturer of corrugated cardboard boxes, the appropriate printing method should be selected according to the characteristics and use of the production carton.