Corrugated box intaglio preprint technology innovation

From 1871, American Albert Jones invented a single-faced corrugated board to a variety of corrugated paper products. It has a history of more than 100 years. Corrugated paperboard boxes have the advantages of light weight, good pressure resistance, resistance to puncture, tearing and buffering, shockproof, easy processing and molding, as well as good printability, can be recycled, and have no pollution to the environment. Has become one of the most widely used packaging materials in modern packaging. Corrugated cartons production in China accounts for about 30% of Asia and 10% of the world. In order to improve the quality and performance of corrugated paper, corrugated carton pre-printing process has always been a concern. At the just-concluded 6th Beijing International Printing Technology Exhibition, many suppliers including Shaanxi Beiren Group exhibited cardboard boxes. Preprinted gravure printing machine.

Figure 1: Flow chart of corrugated carton preprinting

First, the development of corrugated carton printing
The domestic corrugated box printing process has gone through four stages: first, a simple monochrome text printing; followed by a monochrome halftoning image and a two- or more-colored line print; and then the prevailing color halftone image superimposition; With the continuous development of the society, the printing industry of corrugated cartons has gradually approached the high-end, high-quality, and visually intense colorization, and a large-volume, high-quality color carton preprinting process has emerged. Because the preprinting was first printed on corrugated cardboard, the corrugated paper production line was compounded and cut, resulting in a qualitative leap in the color printing level of the corrugated box. With the popularity of the domestic laser platemaking industry, paving the way for gravure preprinting, gravure preprinting is currently one of the best process methods for obtaining high quality carton at home and abroad.

Figure 2: Comparison of preprinted and postprinted corrugated boxes

Second, the traditional flexo and offset printing corrugated box printing process
Corrugated cartons usually consist of two processes: printing and forming. The printing process equipment includes offset printing, flexo printing, gravure printing and screen printing. The molding process equipment includes single-sided machines, cardboard lines, and slotted/die-cut/glued box machines. Printed substrates can be sheet-fed, web, and multilayer paperboard. Traditional flexographic direct after-printing process is printed by cardboard printer. Corrugated cardboard is composed of face paper, core paper and liner paper. It has a hollow structure. The surface of corrugated paperboard is uneven, and the pressure at the valley radius and valley peak is inconsistent. There will be a washboard phenomenon. At the same time, the traditional flexographic printing presses are not accurate and the printing quality is low. It is difficult to realize the function of packaging and promotion of goods. Sheet-fed offset printing is a traditional pre-printing method. It is currently the main processing method for high-grade color carton in China, but the offset printing pre-printing method has complicated processes, many processes, low efficiency, and poor environmental safety. During the process of confrontation, because of the pressure applied to the corrugated medium and the excessive moisture left by the colloid, the technical indexes such as the flat compressive strength, bursting resistance, and adhesive strength of the carton are difficult to meet the requirements for packaging of high-grade goods.

Third, the characteristics of gravure preprint
As one of the four major printing methods, gravure has some advantages that other printing methods cannot replace. It has the characteristics of thick ink layer, uniform ink saturation, high saturation, bright and bright color, etc. The printed product is more in line with the Orientals. The concept of aesthetics, so the use of gravure pre-printing may be more suitable for the actual situation of packaging companies in China. It is also due to the good foundation of gravure printing in China, and it has become the starting point for preprinting of gravure webs by the packaging industry. With the reduction of the cost of platemaking and the reduction of the price of gravure printing presses, the market share of gravure printing is increasing, and it will certainly become a good choice for high-quality corrugated box processes.



Figure 3: Comparison of Corrugated Box Printing Methods

Gravure Preprinted Carton Benefits:

● High-quality, high-intelligence color box can be obtained. The network is delicate and expressive. The color is bright, uniform and full. The color is consistent. The viewing with the naked eye is basically the same as the offset printing effect. The large area solid printing effect is excellent.
● The preprinted paper is directly formed into cardboard through the corrugated cardboard production line, avoiding the destruction of the corrugated medium by the ink printing machine and the gluing machine, and will not cause the stamping damage to the corrugated medium, so the carton will eventually obtain higher strength.
● It can apply anti-moisture bright moisture-proof oil on-line to enhance moisture resistance and abrasion resistance. It can also carry out high-speed laminating. It can be printed at the same time. It can improve the production efficiency of automatic corrugated box line.
● Multi-color printing can be performed at a time. Special inks such as gold ink and silver ink can also be printed. The printing speed can be as fast as 150 to 200 m/min. With high production efficiency, it can meet the long-term needs of short construction period and large output. The entire process of printing production can maintain high color stability and printing quality.
● Simple process, less variable factors, so simple quality control, vertical and horizontal automatic tracking system, can guarantee the accuracy of overprint, easy production management.
● Large-format printing is possible, and domestic gravure printers that have been produced can be printed on 2500×1700 mm carton layouts.
● The users of gravure printing presses have strong flexibility. They can not only undertake carton pre-printing, but also print cartridges, Tetra Pak, cigarette packs, and decorative papers and other packaging items.

Gravure printing process defects
● It is mainly suitable for large-volume products and is not suitable for short-lived products.
● The requirements for printing equipment are relatively high.
● The plate making cycle is relatively long.

Figure 4: Effect of corrugated carton preprint and postprint on strength

(to be continued)