Overview of the hottest corrugated box printing me

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Overview of corrugated box printing methods (Part 2)

(2) characteristics of gravure preprint

A. advantages of gravure preprint

① color cartons produced by gravure preprint can obtain high-quality, green and environmental friendly ink prints. The inking volume of gravure printing is larger than that of other printing methods. Gravure printing brush ink color is full, ink layer is thick, and there is a three-dimensional feeling; Bright colors, rich layers and high definition. Among various printing methods, the printing quality is the best and stable. The tension control system of gravure printing machine controls the stable operation of the machine, and the automatic chromatic control system can ensure the accuracy of overprint to reach 177; 0.1 mm. Gravure printing has sufficient drying after each color printing, and the printed matter is more firm. The number of printing lines after ordinary gravure printing can reach 200l/in. Even if the paper with high surface smoothness is used, gravure printing can also obtain high printing quality. Pre printed water-based intaglio ink is used for printing, which is non-toxic and pollution-free, and meets the requirements of environmental protection. At present, the gravure paper and ink produced in China are relatively mature and can withstand the requirements of high temperature of 200 ℃ and hot plate friction on the corrugated paper production line. Gravure printing can also complete printing and varnishing at one time

② the gravure preprint plate has high printing resistance and is suitable for the production requirements of large-scale printing of cartons. Because the gravure plate is a steel chrome plated electric engraving gravure plate, the whole plate is protected by a hard metal chromium layer, so even if there is a scraper in constant contact with the plate during printing, it still maintains a high printing resistance, generally up to 3-4 million prints, which is suitable for the production requirements of high-quality and large-scale printing of cartons

③ gravure preprint printing offset printing suitable for continuous patterns wraps the prepared plate on the plate cylinder, so there is always an area on the surface of the plate roller for fixing the plate. Gravure plates are different. Because the gravure plate making operation is directly carried out on the cylinder, as long as the images on the cylinder are seamlessly spliced, continuous patterns can be obtained on the substrate

④ corrugated boxes produced by gravure pre printing have high strength. Because the pre printing production of corrugated boxes is completed on the production line, there is a certain heating and forming time when making corrugated boxes, so the strength of corrugated boxes is higher than that obtained by the traditional method of veneering machine, and it can avoid the damage to the strength of corrugated boxes caused by direct printing, and improve the strength and stamping strength of corrugated boxes

⑤ gravure pre printing has fast printing speed and high production efficiency. Because the pre printing method adopts web gravure printing machine for printing, there is a drying device after each color is printed, and the next process can be entered without powder spraying, and the printing speed can reach 150 meters/minute. In the process of high-speed gravure printing, a roll can be printed in a short time. The printing efficiency can be greatly improved by using the automatic roll changing device without stopping the machine to replace the roll. After printing, it is made into corrugated board on the corrugated paper production line, which is much faster than the traditional veneering machine

b. deficiencies of gravure pre printing: gravure plate making is complex, and the cycle of making a steel chrome plated electric engraving gravure cylinder is generally 5 ~ 10 days, and the price is higher, which is 8 ~ 10 times that of flexible plate; Gravure printing technology is relatively complex, relatively many processes, and the investment of the whole production line is relatively large

(3) characteristics of flexographic preprint

a. advantages of flexographic preprint:

① it is non-toxic, non polluting and conducive to environmental protection. It is a green printing method, which has great advantages in the printing of green cartons such as food boxes and medicine boxes

② it can print large-scale multi-color, high-quality color packaging boxes. The widest web flexographic printing machine abroad can reach 1.8 meters, and the satellite flexographic printing unit can be made into 6 colors. It can print wide format, multi-color, high-quality and high-precision color cartons

③ low cost. The low cost of flexo printing has formed a broad consensus abroad, and there are still different opinions in China. The main reason is that most of the flexo printing machines and flexo printing plates used in China rely on imports, resulting in higher costs. The cost of offset printing and gravure printing in this regard is relatively low. With the localized production of flexographic printing equipment and its plates in China, the cost will be gradually reduced

④ different lines are used for printing, with fine print patterns and strong consistency. 100l/in, 133l/in and 175l/in can be used to show the pattern, which is delicate and bright in color

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

⑥ fast printing speed and high output. The machine speed of satellite flexographic printing machine can generally reach 250 ~ 300 m/min, which can meet the needs of multiple automatic corrugated production lines

⑦ the range of printing materials is wide, and the paper can be printed from 80 to 400g/m2

b. deficiencies of flexographic preprinting

① in the process of plate making, the highlight part of the pattern shows obvious polarization, or the small but improved product performance points (points below 8%) have been lost when printing, becoming absolutely impossible; The increase rate of the first point is too large, and it has become a point close to the middle tone. In the dark part, about 85% of the points will be merged, in the field state. It can be seen from this that when flexographic printing uses amplitude modulation points for step reproduction, the range of steps that can be copied is narrow, about 8% - 85%. In other words, when printing more than 85% of the area, due to the increase of dots, there will be merging phenomenon, so that the dark tone area is pasted and there is no hierarchy; When printing areas below 8%, it is difficult to "stop" on the printing plate because the dot is too small. If the design is smaller than 8%, it cannot be shown in the actual printing process. Therefore, some manuscripts with rich levels are difficult to present their rich levels and colors with flexo

② in terms of the number of lines added in printing, the maximum number of lines in offset printing and gravure printing is higher than that in flexo printing. The ideal number of lines for flexo printing is generally below 150l/in, and more than 175l/in, which will increase the difficulty of flexo plate making and greatly shorten the service life of the plate. ③ Too thin lines and too small words should not be used. Due to the deformation of flexo in the printing process, too thin lines and words are prone to deformation. If there are small anti white words or anti white lines, due to the shallow relief, it is very easy to cause paste death. Therefore, try to use thicker lines, and the color contrast between decorative lines and main lines should be larger. Through the above analysis, it can be seen that pre printing is an ideal way to produce corrugated boxes with high quality and in large quantities

2. Several special printing methods

2.1 plastic gravure composite carton process

when using a single-sided corrugated production line, if the surface paper needs to be covered with bright film after printing, and the production batch is large, you can not print on the surface paper, but use gravure printing to complete gravure printing on the plastic film, add white primer, and then compound the printed plastic film with the surface paper first, and then complete the cartoning according to the conventional carton forming process

the characteristics of this process are:

① the production cost of cartons is low. When the production batch often neglects the attachment, this process can greatly reduce the printing cost of face paper and the material cost of face paper. Because face paper does not need printing, it can be coated with white board without approval, which greatly reduces the cost of face paper

② exquisite printing. Because plastic gravure printing is used, the printing effect can be comparable to that of offset printing. Special attention should be paid to using this process. 2. When carbon nanotubes are used for plate making and printing, the size change and deformation of the plastic film should be fully considered, otherwise, the paper on the top of the carton will be out of alignment with the lower paperboard

2.2 coated paper gravure composite carton process

this process can be used when the production batch is relatively large, film coating is not required, and the printing effect is good and the cost is low. This process is to use a paper gravure printing machine to print a relatively thin (60 ~ 90g/m2) coated paper, and then combine this beautifully printed coated paper with ordinary slag paper or carton paper, as a whole, as the top paper of the carton, and then mount it and form the normal carton

the characteristics of this process are:

① the production cost of cartons is low. The main reason for the cost reduction is to change the white board into low gram weight coated paper and compound it with cheap box board paper, which reduces the material cost

② exquisite printing. The printing effect of paper gravure printing is very exquisite

③ gravure plate making is complex and expensive, which is not suitable for printing carton products with frequent revision

④ the operation and control methods of paper lamination, cartoning and other technological processes in the printing plant should be carefully explored, continuously accumulated and reasonably implemented, otherwise it is easy to lead to the increase of scrap rate

2.3 direct offset printing corrugated box process

the direct offset printing process of corrugated box has been relatively mature in foreign countries. It is to directly put the corrugated board on a special offset printing machine for printing, which is suitable for processing thin corrugated boxes

this process can not only ensure the good formability of cartons, but also complete exquisite face paper printing, but the printing machine used is relatively expensive. In the next few years, this process may become a new development direction of high-end carton printing in China

2.4 wire printing corrugated box

wire printing corrugated box process adopts direct printing. Because the inking rate of the silk plate is directly proportional to the hole spacing of the silk, the resolution of the silk printing is not high, and the image accuracy is low. The conventional number of lines is 60 ~ 80 lines/inch. The corrugated box with silk printing has the following advantages:

① the printing format can be large or small

② printing can be completed before mounting into boxes, or after mounting into boxes

③ the ink color of silk printing is thick, its color saturation is high, and the visual effect is strong, especially in the field of spot color printing, the effect is better

④ plate making is easy and low

⑤ low printing cost

⑥ the printing quality is relatively stable. The disadvantage of wire printing corrugated box is that it is not suitable for linkage production line and the production efficiency is low

3. Conclusion

through the above analysis, we can see that there are many methods of carton printing, and each method has its advantages and disadvantages. We should choose the appropriate printing method according to the characteristics of the produced cartons. In particular, pre printing is undoubtedly the best way to produce corrugated boxes with high quality and in large quantities

source: corrugated box

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