Corrugated cartons are an ordinary paper packaging product that is inseparable from our lives and production. The printing quality of corrugated cartons is not only related to the appearance quality of corrugated cartons, but also affects the sales prospects of the packed products and the image of the commodity production companies. Therefore, it is particularly important to analyze how to improve the surface printing effect of corrugated boxes, how to choose a suitable printing process, and further reduce the processing cost of the carton. Here we will discuss these aspects.
First, corrugated board processing technology
Corrugated board processing technology is mainly divided into two categories.
1. Production process of automatic corrugated board production line
The corrugated board production process has been widely applied, and has the advantages of large production volume, large carton forming volume, and good quality of the crucible type. The corrugated board produced by this process is usually made into cartons through processes such as water-based printing, slotting, sticking, and forming. The cartons produced by this process are mainly used for transport packaging.
2. Production process of semi-automatic corrugated board production line
The corrugated board production process is to print the surface paper first, and then it is coupled with the corrugating medium core paper and cardboard. The corrugated paperboard produced by the process is conventionally made into boxes by die-cutting indentation, adhesive nailing and the like. The carton produced by this process has good molding quality and good surface treatment effect. The cartons produced by the compromise process can be used for sales packaging.
Second, the conventional carton printing
Conventional carton printing methods include flexo, offset and screen printing.
1. Flexo printing corrugated carton
The conventional flexographic printing corrugated box process prints directly on corrugated board, using water-based inks, so it is also a process of watermarking.
Flexo printing has the following features:
(1) Large-format, wide-format flexographic printing presses have a maximum width of 2.5 to 2.8m.
(2) The price is low, flexographic prints are very resistant to print and can be reused; humor prices are also lower.
(3) It can be linked to production, such as printing, slotting, indentation, ordering (sticking) boxes, baling and so on.
(4) Less carton strength is reduced. Since flexo printing is light press printing, there is little effect on the strength of corrugated cardboard.
(5) The printing accuracy is not high, the number of conventional offset printing screens is 175 lines/inch, while the number of conventional screen printing lines in flexo-printing boxes is 35~65 lines/inch, which is a low-precision printing method, and is most suitable for printing text lines and four colors. Although the image printing quality has improved in recent years, there are still limitations.
(6) There are difficulties in making plates, text lines are easy to make, and four-color images are more difficult to make.
(7) The stability of printing quality is not good, mainly reflected in the darkness of the printing ink.
The flexographic plate direct printing process is suitable for the production process of the first type carton, and is currently widely used in the carton factory in China.
2. Offset printing corrugated carton
The conventional offset printing corrugated box adopts the indirect printing method, that is, the cardboard box is first printed, and the printed sheet is then affixed to the corrugated font. Due to the relatively high resolution of the PS version, very fine printing patterns can be printed. The vast majority of high-grade corrugated cartons used for sale packaging in China are offset printing products.
Offset printing corrugated boxes have the following characteristics:
(1) It is not suitable to use paperboard linkage production line. It is only suitable for single-faced corrugating machine and the production efficiency is low.
(2) Limited format, generally smaller than flexo print carton format.
(3) The printing product is very fine, and the number of screens can reach 150~200 lines/inch.
(4) Plate making is easy. It is a conventional plate making of PS plate.
(5) Can finish the surface decoration, such as laminating, polishing and so on.
(6) High printing costs.
(7) The printing quality is relatively stable.
3, screen printing corrugated boxes
The screen printing corrugated box process uses direct printing.
Since the ink ratio of the screen plate is proportional to the hole pitch of the screen, the resolution of the screen printing is not high, the image accuracy is low, and the number of conventional screen lines is 60 to 80 lines/inch.
Screen printing corrugated boxes have the following characteristics:
(1) It is not suitable for the linkage production line and the production efficiency is low.
(2) The printing format can be large or small.
(3) The printing can be completed before pairing and boxing, and printing can also be performed after pairing and boxing.
(4) Suitable for printing non-fine products. The screen printing ink is thick, so its color saturation is high and the visual effect is strong, especially the spot color printing is better in the field.
(5) Plate making is easy and plate making cost is low.
(6) Low printing costs.
(7) The printed matter is relatively stable.
Third, the new printing system box
1, plastic gravure composite carton process
When using a single-faced corrugated production line, if the glossy paper is still needed to be coated after finishing the face printing, and the production volume is large, it may not be printed on the surface paper, and the gravure printing method is used to complete the gravure printing on the plastic film. Apply on a white background, then compound the plastic film with a good factor and the tissue paper first, then follow the conventional carton forming process.
The characteristics of this process are:
(1) The cost of carton production is low. When the production volume is large, such a process can greatly reduce the printing cost of the tissue paper and the material cost of the tissue paper. Because the noodle paper does not need to be printed, non-coated white paper can be used, so that the cost of the noodle paper is greatly reduced.
(2) beautifully printed. Because plastic gravure is used, the printing effect can be comparable to that of offset printing.
It is necessary to pay special attention to the fact that in the process of plate making, it is necessary to fully consider the dimensional change and deformation of the plastic film. Otherwise, the carton face paper will be misaligned with the lower cardboard.
2, Coated paper gravure printing composite carton process
When the production volume is relatively large, no coating is required, and the printing effect is good and the cost is low, the process can be used.
The process is to use a paper gravure printing machine to print thinner coated paper, and then composite this finely-printed coated paper with ordinary slagboard or boxboard paper. The whole is used as cartonboard paper, and then it is used for confrontation and normal carton forming. Processing.
The characteristics of this process are:
(1) The cost of carton production is low. The main reason for the reduction in cost is to convert whiteboard paper to low-weight coated paper in combination with cheap linerboard, which reduces material costs.
(2) beautifully printed. Paper gravure printing is very beautiful.
(3) Gravure printing plates are more complicated and costly, and are not suitable for printing carton products that are often revised.
(4) The operation and control methods of the printing process, such as the face-to-face paper compounding and the box making, must be carefully explored, accumulated, and reasonably implemented, otherwise it is easy to cause an increase in the reject rate.
3, direct offset printing corrugated box process
The direct offset printing process of corrugated cartons has been relatively mature abroad. It is the printing of corrugated cardboard directly onto a special offset press. Suitable for processing thin corrugated boxes.
The process can not only guarantee the good moldability of the carton, but also can complete the exquisite glossy paper printing. However, the printing press used is relatively expensive. At present, it is not yet in line with China's demand standards, and it is not suitable for the carton industry in the near future. Adopted, but in the next few years, this process may become the new development direction of high-grade carton printing in China.
4. Pre-printed and gravure preprinted corrugated box process
This year's development is relatively fast, both of these processes are first to use web printing paper, and then complete the production of corrugated cardboard in the automatic corrugated board production line. Carton printing quality and molding quality are relatively high, but the investment is relatively large and it is not suitable for small batch production.
In suffocating the industry in the country, the three kinds of conventional printing methods should be used more generally and become the mainstream method of corrugated box factor. The new type of printing box method, due to the hot spots of equipment, materials, processes, operations and other technology has not yet been fully grasped, the investment is relatively large, the promotion of the difficulty is still relatively large. However, in order to improve the quality of cartons, reduce the total cost of the cartons, obtain maximum profits, and increase the competitive advantage in the market, it is imperative to adopt a new type of box-making technology.
From the general development of the carton printing process, the plate making and printing technology of the flexographic plate printing corrugated box process needs to be improved as a whole. The plastic gravure printing, the carton gravure printing and the web offset printing process need to be promoted and improved. Direct offset printing and preprinting Corrugated box production process should also arouse our concern.
Source: Full Print Network
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