Analysis of corrugated board printing technology

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Analysis of corrugated board printing technology

release date: Source: China's paper industry

with the social progress, 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 the inner packaging directly facing consumers or the middle packaging and outer packaging that may be discarded in the process of product transportation, storage and transportation, plays a vital role in product publicity and brand building. The role of corrugated boxes, which were originally used as product transportation packaging to protect products, has also been enriched, which directly led to the improvement of people's requirements for the printing quality of corrugated boxes, making the printing methods of corrugated boards gradually diversify

I. corrugated board printing process

at present, the printing of corrugated board is mainly flexographic printing, accounting for more than 70% of corrugated board printing in China and more than 85% in Europe and America. The printing process can be divided into two categories: first, direct printing process, that is, printing directly on the formed corrugated board; The other is the pre printing process, which is to print the corrugated paper first, and then fit the printed paper with the corrugated inner paper to form corrugated board

1. direct printing process

direct printing process is one of the main printing processes of corrugated board at present. Direct printing mainly includes two printing methods, flexographic printing and offset printing, of which flexographic printing is absolutely dominant. The technological process of direct flexographic printing is: corrugated board production, direct printing of paperboard, film cutting and slotting, and adhesive nail box. Direct offset printing is mainly used for the printing of micro corrugated board. Its technological process is: production of micro corrugated board - direct offset printing of micro corrugated board - film cutting and slotting - adhesive nail box

(I) flexographic printing is a printing technology that uses a flexographic plate. It uses water-based ink or solvent based volatile ink to transfer ink through a grain transfer ink roller. Flexographic printing has the characteristics of fast ink drying, high printing speed and low cost, which is especially suitable for the printing of corrugated board with low requirements for printing accuracy. Flexographic printing corrugated board has the following characteristics:

① using water-based quick drying ink to replace a new EPN process rising in the field of product packaging in the past. It is also an innovation of offset printing process. However, due to the large printing pressure of offset printing and the use of fountain solution in printing, compression and water absorption will reduce the strength of corrugated board. Therefore, at present, direct offset printing can only be printed on micro corrugated board with high strength and ultra-thin, and special blanket with strong compressibility and good ink absorption and transfer performance should be used to prevent the decline of corrugated board strength and the phenomenon of "washboard"

(3) in addition to the above two main EPN methods, the direct printing method of corrugated board is also silk printing method. The printing format of silk printing can be large or small, the plate making is easy, the printing cost is low, the printing ink is thick, and the color saturation is high. 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 with silk is only suitable for the production of corrugated cardboard by a single machine and when the batch is small

2. Preprint process

although flexographic printing, which plays a leading role in direct printing, has many advantages, there are still many difficulties in printing patterns comparable to offset printing and gravure printing. In order to obtain a beautifully printed corrugated board, this opinion clearly points out that many manufacturers use preprint process. The process flow of pre printing process is: pre printing face paper and corrugated composite bonding produced by the production line - Computer longitudinal cutting - computer transverse cutting - film cutting and slotting - bonding nail box. There are many printing methods for corrugated board pre printing, including offset pre printing, gravure pre printing and flexographic pre printing

(1) offset preprint is to use offset printing to print the corrugated paper, and then use a single machine to re frame the corrugated. The process flow is: offset printed sheet fed and single-sided corrugated cardboard rolled by a single-sided machine - veneering machine composite bonding - die cutting and slotting - bonding nail box

offset preprint can obtain cartons with exquisite patterns, but it also has some other problems, such as complex process, high production cost, long production cycle, low carton strength, limited printing materials, and printing width. Rick Chen, market development manager of PPG Asia Pacific region, will also discuss with everyone at PPG booth that PPG special yarn has limited utilization in air filtration, high carton scrap rate, large production site, and high labor intensity, Especially for large quantities of packaging carton printing. Due to the high production cost and long cycle, it can't keep up with the customer's demand for products. From the development trend of foreign packaging industry, offset preprint methods will be gradually reduced in the production of corrugated board

(2) gravure pre printing is to pre print the required exquisite patterns on the wide web

paper (carton face paper) by using gravure printing technology. Then the corrugated board production line on the web printed face paper is made into corrugated board, and then die-cutting indentation is used to form a box

the characteristics of gravure preprint are:

① among various printing methods, the printing quality is the best and the most stable

② adopt water-based ink, which is green and environment-friendly

③ the printing plate has high printing resistance with dial and digital dial, which is suitable for the requirements of large-scale printing production of cartons

④ suitable for printing continuous patterns

⑤ fast printing speed and high production efficiency

⑥ plate making is complex and the printing plate price is high, which is 8-10 times that of flexible plate

⑦ the process technology is relatively complex, there are relatively many processes, and the printing cost is high

(3) flexographic preprint is to use a flexographic printing machine to print on the web. After printing, the material is still received into the web. Then the printed web is used as the corrugated board production line on the surface of the carton to make the corrugated board. Then the die-cutting machine is used to cut the indentation into the carton. The characteristics of flexographic preprint are:

① it is non-toxic and pollution-free, which is conducive to environmental protection. It is a kind of green printing method, especially for more durable product design in a more despicable environment. It has great advantages in the printing of green cartons such as food boxes and medicine boxes

② large format, multi-color and high-quality color packaging boxes can be printed

③ a wide range of printing materials, which can support EOG/㎡ paper and paperboard

④ different lines are used for printing, with fine print patterns and good consistency

⑤ the strength and stamping strength of corrugated board can be improved by laminating and bonding the face paper and corrugated board at one time on the corrugated board production line

⑥ low printing cost, fast speed and high output

⑦ the points of high light and dark tone are easy to lose, which is suitable for the replication of 8% - 85% tone areas

⑧ do not copy too small text lines. Due to the deformation of flexo in printing, small words and lines expand and paste

II. Comparison between direct printing process and preprint process

although direct printing is still one of the main printing processes in corrugated board printing at home and abroad, except for the advantages of simple process, fast speed and short cycle, other aspects are inferior to preprint process. Compared with direct printing process, pre printing process has some obvious advantages: first, it can obtain higher printing quality and wider adaptability. Second, pre printing can print at a richer level, and the printing quality is more stable and reliable. Third, it can make the corrugated box obtain higher strength. This is because pre printing does not need to imprint the paperboard after it is formed. It can avoid corrugated deformation and weaken the strength of the paperboard. When using direct printing, because each color printing will cause more or less deformation of the corrugated board. The more the number of colors, the greater the influence on the deformation of the corrugated board. Therefore, pre printing has become an important development trend of corrugated board printing, especially high-end exquisite cartons, including large and heavy cartons, are more suitable for pre printing

in a word, there are many printing methods of corrugated board. In order to meet the requirements of various packaging, its printing methods will continue to increase. These printing methods have their own advantages and disadvantages. They are suitable for different requirements and uses. As a manufacturer of corrugated cardboard boxes, it should choose the appropriate printing method according to the characteristics and uses of the production boxes

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