The first thing that should be considered in the direct offset printing of micro-corrugated cardboard is the uneven surface of micro-corrugated cardboard. Unlike the printing of plain paperboard, the printing of fine corrugated cardboard must take place on uneven surfaces caused by corrugations and troughs. Offset printing on uneven substrates is difficult to perform, and printing quality is difficult to guarantee.
Substrate irregularities are a major challenge for fine corrugated board printing. The structure that the printer must handle the grooves and backs corresponds to the three-dimensional plate structure. Another difficulty lies in the fact that in fact the pressure required for the transfer of ink from the blanket to the corrugated paper is a certain contact pressure in order to achieve a clear image in the grooved portion. This pressure is higher than the effective printing pressure on the smooth surface of the ridge, and it does not weaken the structure and stability of the fine corrugated cardboard. This condition is the starting point for direct offset printing on fine corrugated cardboard. Many corrugated paper suppliers already provide the necessary material quality to accommodate non-stop printing.
The blankets needed for direct offset printing on micro-corrugated cardboard should be quite flexible. It enables the printing process to use the highest printing pressure without causing too much pressure on the spine. This avoids excessive compression of the groove. In order to maintain the color of the fine corrugated cardboard and the stability of the box type. Due to the optimization of the blanket, the ink can be well transferred to the highest quality of fine corrugated board printing.
Another problem is that the printing needs to transfer ink to the substrate with a certain pressure. In order to make the corrugated paper surface completely printable relative to the corrugation trough, the printing pressure must be higher than the printing pressure required for the smooth surface material, which inevitably generates a greater pressure at the crest of the micro-corrugated cardboard. , resulting in a decrease in the strength of the fine corrugated cardboard.
In order to solve the above problems, a special rubber blanket was developed. The elasticity of the blanket was smooth. Therefore, even if a large amount of pressure is applied during printing, the pressure at the crest of the paperboard will not be greatly increased. This avoids the damage of the fine corrugated cardboard and ensures that the overprinting accuracy and the fine corrugated cardboard stacking are smooth. The emergence of such blankets has greatly promoted the development of direct offset printing of fine corrugated board.
One of the most important conditions for the direct offset printing of fine corrugated board is to optimize the ink so that the effect of the washboard is minimized. The development of the blanket is mainly for the printing of fine corrugated cardboard, compensating the change in the printing pressure between the back and the groove of the fine corrugated cardboard by its high compressibility. However, the remaining pressure difference can still cause the ridges and recesses to expand and ink overprint to varying degrees. This needs to be compensated by the ink during the printing of fine corrugated cardboard. Print tests show that optimizing the ink significantly reduces the washboard effect. It prints in a wider color gamut and has been shown to be best suited for the printing of fine corrugated cardboard.
4. 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.
5, limited format, generally smaller than the flexo printing carton format.
6, printing products are very fine, the number of screen lines can reach 150 to 200 lines / inch. The printing quality is relatively stable.
7, due to more post-process, so that the strength of cardboard.
8, ink generally contains benzene, there is a certain degree of pollution.
Direct printing on micro-corrugated cardboard, due to the effect of printing pressure, the strength of the carton will certainly decline, which is a major drawback of direct printing of micro-corrugated cardboard. The effect of printing on the strength of micro-corrugated board is mainly reflected in the printed area and the printed position. In general, as the printing area increases, the board strength decreases proportionately. The total printing is reduced by about 40%; transverse belt printing is reduced by about 35% at the center width of 50mm; about 30% at the width of the lower edge of 50mm; and the width of printing is reduced by about 30% at the upper and lower sides by 50mm; on the side and end of the carton. The central part is reduced by about 5% in vertical printing of 50mm.
With the continuous development of printing technology and process, the printing of fine corrugated cardboard will further develop. There will be more competition between several printing methods of micro-corrugated cardboard, and this competition will also promote the development of micro-corrugated cardboard printing. Several printing methods of micro-corrugated cardboard will occupy a certain market with its own characteristics.
The successful application of the direct printing of micro-corrugated board technology by the offset press has made corrugated box packaging and printing enter a new stage of development. Due to the high quality and low cost of direct offset printing on micro-corrugated cardboard, the printing and packaging industry can no longer ignore this technology.
The design concept and market demand for displaying products and promoting products through storage and transportation packaging also promoted the rise of direct-printing micro-corrugated cardboard technology by offset presses, and also established new printing quality standards for corrugated paper box packaging. Of course, this does not mean that only offset printing will have the future of direct printing of fine corrugated cardboard. Thick cardboard boxes are still printed mainly by flexo printing. Many long-lasting cardboard boxes will still use flexo printing because of their relatively simple shapes and design patterns. Similarly, high-quality corrugated cartons will also be offset-printed and then processed. Despite all kinds of restrictions, direct-printing micro-corrugated cardboard offset printing currently occupies a certain market share and will continue to grow.
