With the continuous development of printing technology, the sheet-fed offset printing market has also continued to develop in the direction of increasing production efficiency, reducing printing costs, and adding value. The advent of hybrid inks, it is adapted to the development trend of sheetfed offset printing market. The hybrid ink is essentially a component that incorporates conventional offset inks in the formulation of UV offset inks, and combines the advantages of both UV offset inks and conventional inks in terms of performance. While retaining the fast-curing properties of UV offset inks, it not only solves the problem of gloss fade when applying on-line coating with UV varnish on traditional inks, but also greatly improves the printability than UV offset inks.
In recent years, UV inks have been used more and more widely as the fastest-growing environment-friendly ink. The global UV market is growing at an annual rate of 10%.
In order to survive in the fierce market competition, printing companies must improve product quality, so they must choose the right equipment and consumables. Since UV inks give special value to prints, their use is constantly increasing.
In the field of printing, UV offset printing has become an important method for cover books, advertising posters, and decorations. UV inks are favored by people due to their good decorative effect, non-volatile harmful substances, and fast fixation. The application of UV technology in offset printing has shown great vitality. Before discussing the application of UV ink in offset printing, we first understand the principle and characteristics of ink.
First, the application of UV ink
The main components of the UV ink include organic pigments, photopolymerizable prepolymers, photosensitive monomers, and photopolymerization initiators. The role of each component is shown in Table 1.
UV ink solves the problem of drying in printing with its unique drying method. Its drying principle is to cause the photochemical reaction of the ink by the radiation of ultraviolet rays to the ink, so as to achieve the purpose of ink curing. UV inks have the following two main chemical reactions in the drying process.
1. Photochemical reaction: The photopolymerization initiator contained in the ink undergoes photochemical reaction under ultraviolet radiation to generate free radicals.
2. Chain reaction: Generates free radicals with the ability to initiate chain reaction through photochemical reaction. Chains of unsaturated multi-functional prepolymer, multi-functional prepolymer, multi-functional crosslinking agent and reactive diluent in ink The reaction, cross-linked to produce a three-dimensional structure of the photo-cured product - dry ink film.
Therefore, the drying of the UV ink is mainly determined by the photocuring drying characteristics of the ink, so that the ink has different drying performance under light and light-free conditions, that is, the ink does not receive light when printing, and the rheological properties are maintained stably. Printed state; printed by UV radiation, rapid drying, to meet the post-press process operations, greatly improving the production efficiency, and greatly improved the ink drying adaptability.
Second, the advantages of UV ink
1. Volatile Organics: Most UV products contain little or no organic solvents, no solvents will attack the printed matter, and do not pollute the human body and the environment.
2. Suitable for non-paper substrates: Can be printed on common substrates, and can also be printed on non-absorbent materials such as film, synthetic paper, metal or plastic.
3. Suitable for instant printing treatment: It can be quickly cured after irradiation with ultraviolet light.
4. Use less ink: Because UV ink does not contain solvent, it only needs 1/3 to 1/2 of the amount of ink used to achieve the desired effect.
5. Strong color matching: Adjust the viscosity, hue and lightness of the ink, then you can produce rich colors. If you mix two or more basic colors, you can get a variety of colors.
6. Opacity is easy to control: pigments or pigments can be added in the extension base to achieve the desired brightness according to the standard ratio.
7. UV ink under certain printing conditions can be used for ice, refraction, sanding, wrinkles and other special effects.