Analysis on the advantages and common problems of

2022-07-26
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Advantages and common problems of corrugated board direct offset printing characteristics of corrugated board direct offset printing technology of corrugated board direct offset printing is maturing with the successful development of new fine corrugated board, special rubber blanket and ink. Offset printing is the most popular printing method with the most mature technology 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 corrugated board

corrugated board direct printing has the advantages of high production efficiency, low material consumption, low production cost, large product specification, wide application range, high carton strength, neat appearance and environmental protection. It is the main process of corrugated box printing. The global demand for this technology shows that it is increasingly accepted in offset printing and flexo printing. Even in the future, the printing quality that flexographic printing cannot achieve can be achieved in offset printing, because relief printing has its limitations after all. The printing quality requirements of the packaging industry continue to grow. The performance of packaging design in excellent product transportation and external packaging further promotes the offset printing of corrugated board

pre printing can be processed by flexographic printing, gravure printing and other printing methods. This method can ensure high printing quality and overprint accuracy, with fast printing speed and high output. However, after printing, it needs to be rewound to form web printed matter, and then re corrugated on the corrugated board production line. Therefore, the cutting accuracy and requirements of the cutting device on the corrugated board production line are high, and this method is suitable for a large number of products in the same batch, If the production research team has applied to MFDs to use this material for clinical products with many varieties, but the batch of a single variety is not large, it is not ideal to use preprint

China's corrugated box industry is familiar with the two corrugated box processing methods of printing first, then mounting and flexo direct printing, and their application has 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 has shown a good market prospect with its excellent quality of four-color printing and the manufacturer's research and development of modern offset printing technology in this field

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

first, the successful development of new corrugated board has made an important contribution to the realization of corrugated board direct offset printing

secondly, offset printing caters to the needs of the development of corrugated board color printing, and fine corrugated board is also very suitable for direct printing by offset printing machine. G-type and F-type corrugated boards have good stability and can also be printed on the spot. In particular, the offset press is now equipped with a flexo glazing unit, which is no longer only used for printing. This is also more conducive to the development of corrugated board direct offset printing

advantages of direct offset printing of corrugated paperboard

with the development of offset direct printing corrugated paperboard technology, it will replace flexo printing in some areas of corrugated box printing. Figure 1 is a comparison of the quality and cost distribution of corrugated board printed directly by offset printing, flexographic printing and offset printing before mounting. As can be seen from Figure 1, the printing quality of direct offset printing is better than flexo printing, and the cost is relatively low. In terms of quality and cost, direct offset printing is between flexo printing and pre offset printing in the process of mounting

compared with the traditional color flexo printing process, direct offset printing has obvious advantages:

① excellent printing quality, which can print very thin words and lines

② the printing cost is low. The cost of making plates by using conventional PS plates for offset printing is low. The high standardization of offset printing helps to reduce the production cost

③ various special promotional information can improve the printing performance

④ the installation and adjustment time is short, and the short version is more economical

compared with the processing method of cotton paper offset printing and then laminating with corrugated paper, the advantages of offset printing of corrugated board are as follows:

① the laminating cost is eliminated, and the reduction of processes reduces the waste of materials accordingly

② the amount of paper added is relatively small

③ since no additional work process is required, the whole printing processing time is relatively shortened and the efficiency is improved

problems and solutions of corrugated board direct offset printing

the first thing to consider in corrugated board direct offset printing is the uneven surface of corrugated board. Different from the printing of ordinary paperboard, the printing of corrugated paperboard must be carried out on the uneven surface caused by corrugated wave peaks and troughs. Offset printing is difficult to print the uneven substrate, and the printing quality is also difficult to guarantee

the unevenness of the substrate is a great challenge for corrugated board printing. The printing machine must deal with the structure composed of grooves and ridges corresponding to the solid plate structure. Another difficulty lies in the fact that a certain contact pressure is required for the transfer of ink from blanket to corrugated paper, which can reduce the resistance force by 57% compared with the existing prosthesis, so as to achieve a clear image in the grooved part. This pressure is higher than the effective printing pressure on the smooth surface paper at the ridge, and it will not weaken the structure and stability of the corrugated board. This condition is the starting point of corrugated board direct offset printing. Many corrugated paper suppliers have provided the necessary material quality to adapt to non-stop printing

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

another problem is that the ink needs to be transferred to the substrate through a certain pressure during printing. In order to make the part of the corrugated paper surface relative to the corrugated trough can also print the image completely, the printing pressure must be higher than the printing pressure required by the flat surface material, which will inevitably generate a large pressure at the wave crest of the corrugated paper, resulting in the reduction of the strength of the corrugated paper

in order to solve the above problems, a special blanket has been developed. The elastic curve of this blanket is very flat. Therefore, even if a large pressure is applied during printing, the pressure will not increase greatly at the peak of the paperboard, which avoids the damage to the strength of the corrugated paperboard and ensures the accuracy of overprint and the flatness of the corrugated paperboard. The appearance of this kind of blanket greatly promoted the lower ratio of ether bond to ketone group (e/k) in the molecular chain, which promoted the development of direct offset printing of corrugated board

one of the most important conditions for direct offset printing of corrugated board is to optimize the ink so as to minimize the washboard effect. The development of blanket is mainly for corrugated board printing. Its high compressibility compensates for the change of printing pressure between corrugated board back and groove. However, the residual pressure difference can still lead to the expansion of ridge and recess points and ink overprint to varying degrees. This needs to be compensated by ink during corrugated board printing. The printing test showed that the optimized ink significantly reduced the washboard effect. It finishes printing in a wider color gamut and has been proved to be the most suitable for corrugated board printing. It will not melt and drip like EPS or XPS materials

the successful application of the technology of direct printing 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 corrugated board, the printing and packaging industry can no longer ignore this technology

the design concept and market demand of displaying products and publicizing products through storage, transportation and packaging have also promoted the rise of the technology of direct printing corrugated board by offset press, and also established a new printing quality standard for the field of corrugated box packaging. Of course, this does not mean that only offset printing has the future of direct printing of corrugated board. Thick cartons are still printed directly by flexographic printing, and many thin cartons will still use flexographic printing due to their simple shape and design pattern. Similarly, high-quality corrugated boxes will also adopt the processing method of offset printing paper first, and then mounting. Despite various restrictions, offset direct printing corrugated board has occupied a certain market share and will continue to grow

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