Label printing and ink analysis (in)

Second, the choice of label ink

There are many types of label printing inks, which can be divided into three categories based on the solvents used: water-based label printing inks, solvent-based label printing inks, and UV label printing inks.

Water-based ink is safe, sanitary, non-polluting, conforms to environmental protection requirements, and is beneficial to human health. However, it also has disadvantages, such as slow drying speed, low color saturation, poor stability, etc. It is not suitable to print large areas on the ground. It is prone to precipitation and separation for a long time. Layer phenomenon.

Solvent label printing inks have strong adaptability to label materials, stable performance, and high printing quality; however, there are environmental pollution problems and some volatile solvents are harmful to the human body.

UV label printing ink has good performance, reliable quality and wide application range; but the price is high, and it requires special drying equipment, and it also has certain requirements for supporting materials.

When choosing the label printing ink, it is necessary to comprehensively consider the types of printing materials, printing methods and printing conditions, customer's special requirements, post-press processing technology, the use of the label and the conditions of use, cost and other factors. The properties of label printing inks mainly include hue, fineness, saturation, glossiness, adhesion, viscosity, and drying properties. These properties have an important influence on the printing process and print quality.

Third, adhesive printing process

Flexographic printing is a new type of printing technology that is currently popularized in the international printing industry. The advantages are that the machine structure is simple, the cost is low, the printing quality is comparable to that of gravure printing, and the ink layer does not have the advantages of thicker ink layers. Its ink uses water-based ink, does not pollute the environment. Some developed countries’ legislation requires the use of flexible printing for packaging labels used for food and medicine.

Nowadays, the flexographic printing plates are mostly made of solid resin plates, and the inks use universal ink or UV ink. Although the soft version has the advantage of full ink, but the print cable is limited, generally only reach 133 lines / inch, far from meeting the adhesive label users higher and higher quality requirements.

Flexo label printing equipment is all narrow flexographic printing machines, mainly domestically produced, equipment has two characteristics: one is to use UV ink instead of water-based ink. The UV ink has good stability and avoids frequent cleaning of printing plates and inking systems. What is more important is that the color density of the UV ink is greater than that of the water-based ink, which can improve the printing quality of the label. Another feature is the universal use of filmless direct laser platemaking technology, which avoids the loss of small dots, the parallelization of large dots, and the improvement of image layers. The sharpness of text and graphics and the quality of printing are greatly improved.

Flexographic printing, with its high-quality printing products, and the uniqueness of the so-called "green printing", will become the trend for future label printing. Therefore, it is no exaggeration to say that the flexographic printing sticker is the future direction of development. At present, flexographic printing equipment produced by domestic enterprises using domestic resources and foreign technologies is gradually being printed by domestic printing companies in terms of printing quality and price. Accepted, the market share of the application of flexographic printing stickers is growing rapidly.

Fourth, stickers material

Adhesive labels mainly include decorating materials and trademark materials. The materials used for decorating are mainly films, which are mainly used for decorative decals on automobiles and motorcycles, logotypes on trademark windows, reflective films on expressways, and markings on containers. The trademark material is based on paper and film, and is further subdivided into basic labels and variable information labels according to the scope of application. The basic labels mainly include food and beverages, chemical products, pharmaceuticals, office supplies, toys, shampoos, electrical appliances, and hygienic products. Variable information labels include batch numbers, order codes, bar codes, production dates, expiration dates, prices, mailing process information processing, distribution, warehouse management, and inventory data.

Self-adhesive material consists of three parts: face material, glue, and backing paper. Choosing a suitable customer's self-adhesive product is by no means an easy task. According to the experience of professional workers, we must understand from the following aspects:

1. The adhesive is permanent and removable. The performance of adhesives can be divided into two categories: permanent and removable.

2. Emphasize the significance of the surface of the label. Labels for sticker processing may be affixed to the surface of various materials. Different label surfaces have a large impact on performance.

3. Label the surface structure and shape of the substrate. Intuitively, the rough surface of the label requires a highly viscous glue. The surface of the label substrate has a plane and a surface. If the surface of the label has a certain degree of curvature (for example, the surface of the vial having a diameter of less than 3 cm), the surface paper may need a glue having good conformability or strong viscosity.

4. The surface of the label is clean. Self-adhesive materials are best for surface cleaning, dry, oil-free and dust-free label substrates.

5. The adverse effect of plasticity on the glue, that is, the requirement of weather resistance. For example, whether the sticker viscosity needs to be applied under cold, hot, humid or room temperature conditions; whether the sticker is exposed to the freezing point; whether it is for outdoor use, high temperature, humidity or ultraviolet light, And whether it is close to a higher temperature car engine.

6. Printing methods and processing methods on the requirements of self-adhesive materials. After selecting different printing methods (such as flexo printing, letterpress printing, offset printing, heat transfer, and laser printing) and processing methods (such as roll-to-roll, roll-to-single, folding-feed, single-to-single) Before you can decide on printed materials.