Corrugated carton packaging and printing method (1)

Nowadays, the color of corrugated carton packs is becoming more and more eye-catching. This is because corrugated carton packaging has a new task - displaying goods and promoting sales. In large-scale supermarkets, beautifully printed color cartons can attract customers' attention, raise customer interest, and stimulate purchase desires. This requires that corrugated boxes not only have the function of transport packaging, but also have excellent surface printing quality.

In order to safely transport items packed in folding carton packs or plastic Bags (such as liquid milk) to point-of-sales, they are usually packaged in corrugated cartons. The reason is that corrugated cartons are used in the same weight. Compared to cardboard, corrugated board is more impact resistant and can better protect the contents from impact damage. However, you may notice a considerable contradiction, that is, a finely-printed, sales-friendly folding carton or liquid milk package is wrapped in a box that is not printed or only printed with some simple text, if not Opening the box and leaving it at the point of sale, no matter how attractive the folding cartons or liquid milk bags are designed, how beautifully printed and unappealing it is. In this case, the pattern design of corrugated carton packaging is extremely important. This is why more and more corrugated cartons are now printed with patterns. At present, the printing of corrugated paperboard in China is divided into: offset printing, bonding of cardboard into cardboard, direct printing of flexographic printing, pre-printing, and several special printing methods.

The current main methods and characteristics of carton making at home and abroad

1.1 Offset Printing Indirect Corrugated Boxes

The process flow of offset printing indirect printing carton is: single-sided corrugated cardboard (single) ten-offset color printing printing paper (single-sheet) bonding to paperboard die-cutting slotting adhesive nail box

This method uses offset printing of corrugated cardboard paper and then uses a single machine to rehearse the corrugated cardboard. It can print well-designed cartons and improve the printing quality of cartons. At present, most of the high-grade corrugated boxes used for sales and packaging in China are offset printing products.

a. Offset printing corrugated box has the following advantages: 1 The printing product is very fine, and the number of screens can reach 200 lines/inch. 2 Plate making is easy. For the PS plate, the conventional plate making 3 can be surface-refined, such as laminating and polishing. The printing quality is relatively stable.

b. Offset printing corrugated boxes have the following deficiencies: 1 It is not suitable for the cardboard linkage production line. It is only suitable for single-faced corrugating machines and the production efficiency is low. 2 The production process is complicated and the production cycle is long. 3 The carton has low strength, high rejection rate and high production cost. 4 The production site is large and the labor intensity is high. 5 The printing format is limited; delivery time is not flexible enough.

From the above analysis, it can be seen that offset printing indirect printing cartons is not economically cost-effective for a company. Especially for the production of bulk cartons and the production of export cartons, due to high production costs, low efficiency, long cycle times, and inability to meet production needs.

1.2 Flexo printing corrugated carton

The process flow for the production of flexo-printed cartons is: Corrugated board production cardboard Direct printing (flexible version) Die-cutting slotted adhesive nail box

The conventional flexographic printing corrugated box process is directly printed on the corrugated board, using water-based ink, and is currently widely used in cartons in China.

a. Flexographic direct printing has the following advantages: 1 The maximum width of a large-format, wide-format flexographic printing press can reach up to 2.5-2.8m. 2 The price is low, the flexographic printing plate is very resistant to printing force, and can be reused; the ink price is also low. 3 can be linked to the production, such as printing, slotting, indentation, set (sticky) box, bundling and other machines can be completed. 4 Carton strength decreases less. Since flexo printing is light press printing, it has little effect on the strength of corrugated cardboard.

b. Flexographic printing of corrugated board directly, although the printing quality is higher and the efficiency is higher, but there are three difficulties in printing the pattern comparable to offset printing:

1 Corrugated board is difficult to maintain stable during high-speed printing, resulting in difficult to achieve excellent overprint accuracy of four or more colors. In multi-color printing, when the carton printer cannot guarantee sufficient multi-color overlay accuracy, carton printing cannot meet higher requirements.

2 printing pressure control. Unlike other printing methods, flexographic printing transfers ink to paper by means of flexible dots. Due to the rough surface characteristics of the corrugated board, it is difficult for the printing machine to maintain the stability of the board, so that the fine mesh dots are attached to the rough corrugated paper surface with the best printing pressure, so as to achieve the smallest dot diffusion, then it is not necessary to print fine patterns. possible. This makes most of the current flexo-printed carton printing quality in the middle and low state, can only deal with the field, lines and simple patterns of printing, which greatly reduces the carton printing quality.

3 The printing accuracy is not high, the number of conventional offset printing screens is 175 lines/inch, while the conventional screen printing lines of flexo-printing boxes are only 35 to 75 lines/inch, which is a low-precision printing method, and is most suitable for printing text lines and four-color image printing. Although the quality has improved in recent years, there are still limitations.