Analysis on the selection of self-adhesive label p

Analysis on the selection of self-adhesive label printing methods

the current self-adhesive label printing methods in China are mainly letterpress printing, sheet Longteng and HSBC are steel rolling enterprises, and paper offset printing also accounts for a certain proportion, while flexo printing and other printing methods account for a small proportion

due to the printing suitability of film labels, flexo printing or gravure printing is undoubtedly the most traditional printing method. Therefore, label printing plants that have owned flexographic printing machines can generally print both self-adhesive labels and film labels. In the past, enterprises that mainly printed labels with relief printing, offset printing and printing speed measured by stopwatch can realize the conversion of substrate without changing equipment

1. Embossing

embossing is used to print self-adhesive labels. The printing plate is photosensitive resin embossing, and the printing label has the advantage of full ink color. But now the grade of relief printing equipment varies greatly. Some are still using circular flattening embossing machines, some are using ordinary rotary embossing machines, and some have adopted professional oblique back, satellite or unit type self-adhesive label printing machines, so it cannot be generalized during the transformation

professional self-adhesive printing machines, which mainly focus on embossing, have the ability to print film labels, but they need to contact the supplier to replace some relevant parts, such as adding a tension control system controlled by servo motor, adding a film surface treatment unit, and high-end machines can also add accurate but less obvious signs of paper shortage to the registration system. In addition, the power of UV light source should also be adjusted appropriately

for enterprises that print self-adhesive labels with a round press relief printing machine, if they print film labels, they can replace the photosensitive resin plate with a high elastic flexible plate, use water-based ink or UV ink suitable for flexible plate, and change the nature of the ink to adapt to the changes of the substrate

2. Offset printing

offset printing is the main way of printing paper self-adhesive in label printing plants in China. Offset printing is characterized by fine graphics and texts, rich levels, suitable for mass printing, and the printing equipment can be used for multiple purposes, which is suitable for the characteristics of China's label market. However, sheet fed offset printing is not suitable for printing films without absorption on the surface, because film labels are mostly roll to roll printing, which requires volatile dry ink. Offset printing can print thick plastic materials, such as in mold labels and tag tags, but the machine must be equipped with UV curing device, which requires a lot of money

3. flexographic printing

at present, the quality of flexographic printing is no less than offset printing, and even has its own unique features. The advantages of this printing process are simple machine structure, low cost, printing quality comparable to offset printing and gravure printing, and has the advantage of thicker ink layer than offset printing products. Flexo printing uses water-based ink and UV ink, which does not pollute the environment

however, due to the large elasticity of flexo, the gradient reproducibility is different from that of gravure and ordinary relief. The highlight to intermediate tone point of flexo printing increases greatly, the printing contrast is small, and the highlight level is prone to fault. When printing fine graphic labels, in order to make up for the level defect, the highlight part can adopt frequency modulation point, dark tone or intermediate call amplitude modulation to improve the quality. Label printing plants without flexographic printing machines can introduce a laminated narrow width flexographic printing machine dedicated to self-adhesive label printing, which is suitable for film label printing. Because flexographic printing machines all use circular die-cutting, the die-cutting roller is expensive and the production cycle is long, so it is only suitable for long version printing, which is not suitable for the large demand of domestic self-adhesive label short version printing. However, it is a label printing equipment that is easy to transform, and can work online with film cutting, sewing and sealing processes

4. Gravure printing

gravure printing adopts a short ink path inking system for ink supply, web printing, with a high degree of automation, using solvent based ink, and the ink layer dries rapidly, which is the first choice for film printing. Generally, the speed of gravure printing machine is high. The rear end of many gravure printing machines is also equipped with cylinder die-cutting device, which can carry out die-cutting and indentation, and is suitable for the printing of various labels. However, due to the long cycle and high cost of gravure plate making, it is only suitable for mass label production

5. Printing

printing is the most widely adapted printing method for substrates. At present, many printing plants use low-cost printing equipment to contract the printing business of self-adhesive labels and film labels. Label printing is characterized by thick ink color and strong three-dimensional sense. UV ink can be used to print film products. In addition to a handful of rotary printing equipment that can be used for roll to roll label printing, most of the printing equipment are semi-automatic flat printing machines, which can only print single sheet products. The overprint accuracy is not high, and it is not suitable for the film label production equipment supporting the production line. During the business transformation of post press processing technology, we should also pay attention to the corresponding changes of post press processing of labels. For example, when printing self-adhesive labels, the post press processing of self-adhesive is divided into sheet fed processing and web processing according to the application form of labels