How can we produce good quality flexographic prints

Flexo printing is currently widely used in China. Printing materials are increasingly diversified. In addition to traditional printing materials such as coated paper, cardboard, and stickers, there are some new special materials, such as in-mold labels. Composite materials (toothpaste sheet), films, etc. With these new printing materials, many manufacturers are still in the discussion stage. I hope that some aspects to be discussed can inspire people.

A good print requires good design, good printing plate, good ink, good material, good machine, good technology and so on. So how does a good film print come about?

First, the quality of a product depends largely on the design of the product. Each printing method has unique printing features. For example, offset printing has the advantages of small dot expansion, high registration accuracy, and soft and gradual dot gradients. It does not pay much attention to the design of text or gradient during design. If such a design is used for flexographic printing, it would be difficult. First of all, the use of double-color printing for fine text is a weak point for flexo printing. Flexo printing is inferior to offset printing in the accuracy of registration, and the phenomenon of double-sided text appears. In addition, because the expansion of outlets is larger than that of offset printing, especially in high-light locations, it will increase the difficulty of plate making and printing.

However, the thin layer of offset ink is one of its weaknesses. On the contrary, the strength of flexo printing is that the ink layer is thick and suitable for printing on a large area. So for the design of flexo products, we need to avoid the following points:

·Small text, small lines;

· Overprinted lines or text in two or more colors;

· Small anti-white or anti-white lines;

· Photo highlights off the net, or 1% small outlets;

· Make lines and text in Photoshop software;

• Design wide and long bars and solids in the horizontal direction of the print cylinder;

· Avoid long and wide gradient designs in the printing direction;

· A large area of ​​the field with dots and small texts on the same page;

· Inconsistent operating software;

Due to the influence of tension and drying during printing of different materials, different degrees of expansion and contraction will occur, so the design of the product also needs to pay attention to the product's imposition or paper feeding direction. Improper printing direction can adversely affect product registration.

The film material itself is easy to expand and contract, the tension control of the printing is required to be high, and the requirement for the drying system is also high. At present, the equipment for flexographic printing film products in China is basically satellite or laminated. The breadth of satellite machines, coupled with the tensile tension of the film material, requires that the pressure during printing be properly increased. If the traditional printing plate is subjected to pressure, the whole sample will generate a large amount at high light. In expansion, 2% of outlets will expand to 10% to 14%. This kind of highlight will look a little dark, and it is easy to form a hard mouth at the gradual transition. The laser version can make up for this deficiency. For thin-film products, special treatment should be performed on the color separation to formulate a reasonable process to express the advantages of flexo printing.

At present, the number of lines of domestic satellite-type machine printing products is basically 80 to 120 lines. If the cable products are printed using traditional flexographic printing, the printed results are not very detailed. On the one hand, it is affected by the lower number of lines, on the other hand, due to the expansion of the traditional flexographic outlets. If laser flexographic printing is used, the printed products appear visually finer due to the small dot expansion.

The stability of printing materials is also very important. The hardness and hardness of the film will also have a certain influence on the adhesion of the printing ink. The high density of the ink on the film material is not particularly good, and the softer one is better.

The printing plant should develop a reasonable printing process according to the characteristics of different printing materials, and record the data of each printed product in an effective manner to ensure that when the next production of the order is made, the quality of the printed matter is consistent with that of the previous printing.