Research on the most popular corrugated board prin

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The development of economy, the fierce competition in the market and the increase of people's economic bearing capacity and aesthetic awareness have promoted the improvement of product 91 and packaging quality. Beautifying packaging has become an important means to beautify commodities, publicize commodities and promote sales. For the printing of corrugated boxes, they bought a whole 3-storey office building in CIMC smart valley. The quality has been paid more and more attention by commodity manufacturers and consumers. The printing of corrugated boxes has developed from rough, poor printing quality and monotonous graphics and texts to colorful and exquisite images

type and structure of corrugated board

at present, the types and height of corrugated board mainly include type A (large 4..9mm), type C (medium 3.6 ~ 3.9mm), type B (fine 2.6 ~ 2.9mm), type E (ultra-fine 1.1 ~ 1.8mm), type K (extra large 6.6 ~ 7mm), type F (ultra-fine 0.75mm), type G (ultra-fine 0.50mm), type n (ultra-fine 0.46mm), type O (ultra-fine 0.30mm), etc. Different models are suitable for different occasions and have different printing quality requirements. Generally, the thin corrugated ones have higher requirements for printing quality and are suitable for high-end and exquisite carton packaging, while the thick corrugated ones have lower requirements for printing quality and are suitable for ordinary carton packaging. Even the same model may have different structures. There are 2 layers, 3 layers, 5 layers, 7 layers or even 11 layers. There are U-shape, V-shape and uv-shape. Different structures have different uses, different strengths and different requirements for printing. Corrugated board printing is one of the fastest growing packaging printing in recent years. Therefore, how to improve the printing quality of corrugated board is a very urgent problem for packaging and printing carton factories

printing process of corrugated paperboard

at present, the printing process of corrugated paperboard is mainly flexible printing process, accounting for more than 70% of Corrugated Paperboard Printing in China and more than 85% in Europe and America. The printing process can be divided into two types. One is the direct printing process, which is to directly print on the formed corrugated board. The other is the pre printing process, which is to first print the corrugated face paper, and then paste the printed face paper with the corrugated inner paper to form the corrugated board

1. direct printing process

this kind of printing method is one of the main printing methods of corrugated board at present, including flexographic printing and offset printing, in which flexographic printing is absolutely dominant. Its process flow: corrugated board production - cardboard printing - die cutting slotting - nail box

① flexographic printing technology is a printing technology that uses photosensitive resin with good elastic deformation performance as plate material, and uses water-based ink or solvent based volatile ink to transfer the ink directly from the printing plate to the substrate

this kind of printing is the best method for direct printing on corrugated board. It is very suitable for corrugated board printing. It mainly has the following characteristics:

a. water based ink: at present, the flexo printing ink printed on corrugated paper basically uses water-based ink, which has no toxic volatile gas, good absorption, fast drying, green environmental protection, especially suitable for packaging and printing of food, drugs, cosmetics, etc

b. the flexographic printing pressure is light, and the layout is soft and elastic. Due to the corrugated board, which is empty in the middle, it can not bear large printing pressure. At the same time, it will be uneven in the stamping process, and the stress will be large at the ridge peak. In a work flow at the ridge Valley, all different medium-sized equipment and controllers are set with a hard layout, which will lead to serious "washboard" stripes. At the same time, it will make the strength of the corrugated board worse, or even collapse the corrugated board. The flexographic printing pressure is light, and the printing plate is soft and elastic. It can prevent errors caused by misinformation. It is expensive or

c. the machine has simple structure, easy operation, good quality control, fast printing speed and high production efficiency

d. the printing plate has high printing resistance. It is suitable for mass production and reduces the cost

e. the printing machine can produce in linkage with other processes, such as slotting machine and indentation machine, which improves the production efficiency

f. the printing accuracy is not high. It can only be used for some text lines and field prints, and can be used on some packing cases that do not have high requirements for patterns

g. the strength of corrugated board decreased to some extent due to compression

② offset printing is a printing technology in which the image and text part and the blank part are almost on the same plane through the natural law of oil-water immiscibility. The image and text part only adsorbs ink, and the blank part only adsorbs water. Then the ink of the image and text part is transferred to the substrate through the blanket. Offset printing is not suitable for printing on corrugated board due to high pressure and the use of fountain solution has a great impact on the strength of corrugated board. However, in recent years, with the development of printing machine manufacturing technology and corrugated board technology, offset printing technology has made a breakthrough in the printing of micro corrugated board. It will replace flexographic printing in the field of micro corrugated board. Compared with flexographic printing, the packaging printing materials using direct offset printing have clear and exquisite images, colorful, rich layers, good visual effects, good strength, light weight, sharp edges and corners, etc., and have gradually become the main printing method for high-end commodity packaging boxes. For example, direct offset printing can be carried out on Roland 700, 900 and Cobolli PIDA 105. However, due to the large printing pressure of offset printing and the use of fountain solution in printing, both pressure and water absorption will reduce the strength of corrugated board. Therefore, at present, direct offset printing can only be printed on the 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 appearance of "washboard"

2. preprint process

at present, the patterns on the packaging boxes are becoming more and more exquisite. The layers are rich and delicate, and the lines are fine. In order to meet this requirement, many packaging and printing enterprises use the corrugated cardboard preprint process, that is, printing the face paper first, and then pasting it into cardboard, which can solve the problem of low product quality. Preprint process flow: face paper printing - face paper and corrugated paper bonding - die cutting and slotting -41- box

pre printing of corrugated paper includes offset printing, flexo printing and gravure printing

① offset preprint

offset preprint generally uses a sheet fed offset press to print corrugated paper to obtain exquisite patterns, and then uses a single machine to re frame the corrugated paper. This process can achieve good results in carton printing quality. The printed matter is very fine, and the number of lines added can reach 200 lines/inch. It is easy to make plates. It can also be used for post-processing of printed surfaces, such as laminating, polishing, etc. The printing quality is stable and easy to control. However, there will be other problems, such as complex process, long production time, unsuitable for linkage production, low production efficiency, limited printing materials, limited format, high production cost, low carton strength, high scrap rate, high labor intensity, large production site, etc., which can not meet the needs of large batch packaging cartons, especially the packaging of export products, and this kind of printing has been used less and less abroad. However, in China, due to the low labor cost, the use of sheet fed offset printing machines is very common, and the offset printing technology is relatively mature. Therefore, this printing method is still used in many places for high-grade corrugated boxes used for sales and packaging

② flexographic printing preprint

flexographic printing preprint is to use the flexographic printing machine to print on the web and harvest the web form. Then the printed web is used as the corrugated board production line on the face paper to make corrugated board, and then die cut into boxes. There are three methods for flexographic preprinting:

a. unit type flexographic printing machine

this printing machine is similar to the unit type multi-color printing machine, and will also show the arrangement of offset printing machines for other uses of Aramid Composite materials. Each color group is arranged in a line in order, and each color group is independent of each other. The number of colors can be combined arbitrarily. Due to the large distance between colors, it is conducive to drying. The printing speed is fast, but the overprint accuracy is not as good as that of satellite type

b. satellite flexographic printing press

this type of printing press has a common large embossing cylinder in the center. The printing cylinder of various colors is around it. Due to the high overprint accuracy of the common impression cylinder, the satellite type can reach ± 0.05mm. it has a wide range of printing materials. It can be applied to paper and paperboard from 30 to 700g/m2, with short printing adjustment time and less material loss. It is the main preprint method that the most research team has tried for another 5 years and waited patiently

c. laminated flexographic printing machine

this kind of printing machine is assembled in the form of combining each independent printing unit layer by layer above and below the ground. Each color group is independent of each other, drying timely, printing fast, occupying less area, easy to cooperate with other processes, and its application scope and overprint accuracy are not as good as satellite type

d. characteristics of preprint of flexographic printing

flexographic printing has developed very fast in recent years. Due to its fast drying, fast printing speed, green environmental protection and low cost, it is especially suitable for corrugated board printing of mass packaging. Specific features are as follows:

◆ use water-based ink. The main solvent of water-based ink is water, which does not contain volatile organic compounds. It is non-toxic and pollution-free. It is a kind of green environmental protection oil ink. It has good printability. The imprinting has good water resistance and wear resistance. It is an ideal printing ink

◆ wide range of printing materials. It can print 30 ~ 700g/㎡ paper and paperboard

◆ large format, multi-color and high-quality prints can be printed. At present, the largest format of the latest foreign machines has reached 2.4m. the maximum number of colors can reach 8

◆ epb0 has fine graphics, good consistency and bright colors

◆ the produced cartons have high compressive strength and impact strength

◆ EPB and j have fast speed and high output. The speed can reach 250 ~ 400m/min. ◆ the machine has simple structure, easy operation, easy quality control and low printing cost

◆ the points of high light and dark tone are easy to be lost, which is suitable for the replication of 8% ~ 85% gradient areas

◆ do not copy too small text and lines. Due to the deformation of flexo in printing, small text lines are easy to deform, expand and paste

◆ the appearance of digital direct plate making technology and plate sleeve technology has further improved the printing quality and printing speed. Basically, any product can be printed

③ intaglio printing preprint

use the intaglio printing machine to print on the web and harvest the web form, and then use the printed web as the corrugated board production line on the face paper to make the corrugated board, and then die cut it into boxes

at present, there are mainly two types: organic group type and satellite type. The arrangement of rollers is similar to the unit type and satellite type of flexographic printing press, but the layout of the unit type in gravure printing press is more reasonable and the technical level is higher. It is the main type in gravure printing at present. The specific features are:

a. the printing quality is the best and most stable among all kinds of printing

b. adopt electronic engraving to make plates with high precision and rich picture and text levels

c. green and environmentally friendly water-based ink

d. the printing plate has high printing resistance up to 300 ~ 4O million printing, especially suitable for long plate printing

e. the printing plate cylinder that can achieve continuous pattern can achieve seamless splicing, that is, the sleeve technology can make the image continuous

f. high impact strength

g. fast printing speed (up to 150 ~ 2oom/min) and high production efficiency

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