The hottest thin corrugated offset printing techno

2022-09-23
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Fine corrugation offset printing technology

fine corrugation offset printing technology is divided into direct printing and indirect printing. This paper introduces these two technologies respectively

I. thin corrugated direct offset printing technology

China's corrugated box industry has been very familiar with the two corrugated box processing methods of printing first, then mounting and flexo direct printing, and their applications have been very common, but they are relatively unfamiliar with preprint and offset direct printing. However, with the gradual improvement of the market and the gradual maturity of the process, direct offset printing with its own excellent quality of four-color printing, coupled with the manufacturer's continuous research and development of modern offset printing technology in this field, fine corrugated board direct offset printing shows a good market prospect

the direct offset printing technology of fine corrugated board is maturing with the successful development of new fine corrugated board, special blanket and ink. Offset printing is the most popular and technologically mature printing method in China, and the printing quality is also widely recognized. It is believed that this direct offset printing method will become a processing means with strong market appeal in China. But at present, this new technology is only applicable to fine corrugated board, especially G-type and F-type fine corrugated board

direct printing of fine corrugated board has the advantages of high production efficiency, low material consumption, low production cost, large product specifications, wide application range, high carton strength, neat appearance and environmental protection. It is the main process of corrugated box printing. With the continuous growth of printing quality requirements in the packaging industry, the performance of packaging design in the transportation of excellent products and external packaging will further promote the application of offset printing of fine corrugated board

pre printing can use flexographic printing, gravure printing and other printing plus t methods, which can ensure high printing quality and overprint accuracy, fast printing speed and high output, but after printing, it needs to be rewound to form web prints, and then re corrugated on the fine corrugated board production line, so the cutting accuracy and requirements of the cutting device on the fine corrugated board production line are high, Moreover, this method is suitable for the printing of large number of outlet guide vanes (OGV) in the same batch, which has been widely used on the cold end components of foreign advanced aeroengines. If there are many product varieties and the batch of a single variety is not large, the use of preprint is not ideal

offset printing can enter the field of direct color printing of fine corrugated board thanks to the following two aspects:

first, the successful development of new fine corrugated board has made an important contribution to the realization of direct offset printing of fine corrugated board. Second, offset printing meets the needs of the development of fine corrugated board color printing, and fine corrugated board is also very suitable for direct printing by offset printing machine. Among them, G-type and F-type fine corrugated board have good stability and can also be printed on the spot. Especially now the offset press is also equipped with 980.7 flexographic printing, which makes a contribution to the national automation industry. The glazing unit is no longer just used for printing. This is also more conducive to the development of direct offset printing technology of fine corrugated board

1. Advantages of direct offset printing of micro corrugated board

with the development of offset direct printing technology of fine corrugated board, it will replace flexo printing in some areas of corrugated box printing. Compared with the traditional color flexo printing process, direct offset printing has obvious advantages

① excellent printing quality, which can print extremely fine words and lines

② the printing cost is low. Offset printing adopts conventional PS plate, and the plate making cost is low. The high standardization of offset printing helps to reduce the production cost

③ the installation and adjustment time is short, and the short version is more economical

compared with the processing method of face paper offset printing and corrugated paper mounting, the advantages of offset printing direct printing of fine corrugated board are as follows:

① the mounting cost is saved, and the waste of materials is correspondingly reduced due to the reduction of processes

② the dosage of paper is relatively small

③ because there is no need for another working process, the whole printing processing time is relatively shortened and the efficiency is improved

2. Problems and solutions of direct offset printing of fine corrugated board

① offset printing is difficult to print uneven substrates, and the printing quality is also difficult to be guaranteed

for direct offset printing of fine corrugated board, the first consideration should be the uneven surface of fine corrugated board

the same as the printing of ordinary paperboard, the printing of fine corrugated paperboard must be carried out on the uneven surface caused by corrugated peaks and troughs

the unevenness of the substrate is a major challenge for fine corrugated board printing. The printing machine must deal with the problem that the structure composed of grooves and ridges corresponds to the solid plate structure. Another difficulty is to master a certain contact pressure necessary for the transfer of ink from blanket to corrugated paper. In order to achieve a clear image in the grooved part, this pressure should be higher than the pressure of effective printing on the smooth paper at the ridge. Here, various elites in the national experimental machine industry are gathered, and it will not weaken the structure and stability of the fine corrugated board. This condition is the starting point of direct offset printing of fine corrugated board. Many corrugated paper suppliers have provided the necessary material quality to adapt to uninterrupted printing

② direct offset printing of fine corrugated board puts forward higher requirements for the elasticity of blanket

the good elasticity of the blanket enables the printing process to use the highest printing pressure without causing too much increase in the back pressure. This avoids excessive compression of the grooves. So as to maintain the stability of fine corrugated board chromaticity and box type. Due to the optimization of blanket, the ink can be transferred well to achieve the highest quality of fine corrugated board printing

③ washboard effect is easy to occur

one of the most important conditions for direct offset printing of fine corrugated board is to optimize the ink, so as to minimize the washboard effect. In fine corrugated board printing, the high compressibility of rubber blanket compensates for the change of printing pressure between the ridge and groove of fine corrugated board. However, the remaining pressure difference can still lead to ridge and recess dot enlargement and ink overprint to varying degrees. This needs to be compensated by ink when printing thin corrugated board. Printing tests show that the optimized ink significantly reduces the washboard effect. It finishes printing in a wider color gamut and has been proved to be most suitable for the printing of fine corrugated board

④ the strength of cartons will certainly decline

when printing directly on fine corrugated board, the strength of the carton will certainly decrease due to the printing pressure, which is a major disadvantage of direct printing on fine corrugated board. The influence of printing on the strength of fine corrugated board is mainly reflected in the printing area and printing position. Generally speaking, with the increase of printing area, the strength of paperboard decreases proportionally, and the full printing decreases by about 40%; For horizontal strip printing, the width of 50ram at the center decreases by about 35%, the width of 50mm at the bottom decreases by about 30%, the width of 50mm at the upper and lower sides decreases by about 37%, and the width of 50ram at the side and the center of the end face of the carton decreases by about 5%

the successful application of the technology of direct printing of fine corrugated board by offset press has brought the packaging and printing of corrugated boxes into a new stage of development. Due to the high quality and low cost of direct offset printing of fine corrugated board, the printing and packaging industry can no longer ignore this technology

second, fine corrugated indirect printing

that is, first print the face paper of the carton, and then mount the printed face paper on the corrugated paper. Offset printing uses conventional PS board. Due to the high resolution of PS board, very fine printing patterns can be printed. At present, most of the high-end corrugated boxes used for sales and packaging in China are offset printing. In the production process of corrugated boxes, offset printing is a pre printing method, that is, printing on the opposite paper first, and then mounting on the fine corrugated board. It is not much different from the general offset printing process, so I won't introduce it here, but simply analyze its main characteristics. The offset printing corrugated box has the following characteristics:

1. It is easy to make plate, which is the conventional plate making of PS plate

2. it can be used for surface finishing, such as film covering, polishing, etc

3. High printing cost

4. it is not suitable to use the cardboard linkage production line, but only suitable to use the single-sided corrugating machine, with low production efficiency. 5. The format is limited, which is generally smaller than that of flexo cartons

6. The printing products are very fine, and the number of lines added can reach 150 ~ 200 lines/inch. The printing quality is relatively stable

7. due to more post processes, the strength of paperboard decreases

8. ink generally contains benzene, which has certain pollution

with the continuous development of printing technology and process, the printing of fine corrugated board will also further develop. There will also be more competition among several printing methods of fine corrugated board, which also promotes the continuous development of fine corrugated board printing

reprinted from: printed in China

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