UV ink development review

First, basic concepts and principles

　　 UV ink is a specially formulated ink that uses ultraviolet light to form and dry the ink. The mechanism of UV ink drying and film formation is a chemical change. Different pre-polymers and different monomers are polymerized into polymers using different UV spectra to generate different energies. Therefore, the UV ink film has good mechanical and chemical properties.

UV inks include UV sanding, UV ice cream, UV foaming, UV wrinkles, UV embossing, UV refraction, UV gemstones, UV light fixing inks, UV varnish, and the like. On the surface of the substrate with metallic mirror gloss, the UV ink is printed on the surface of the substrate with a screen printing process. After ultraviolet irradiation, the UV drying equipment produces unique visual effects, which are elegant, dignified and luxurious. , Exquisite chic tobacco, wine, cosmetics, health products, food, medicines and other products packaging and printing.

UV inks selectively absorb ultraviolet light, and its drying is affected by the total energy of the light emitted by the ultraviolet light source and the distribution of light energy at different wavelengths. Under ultraviolet light irradiation, the photopolymerization initiator in the UV ink absorbs photons of a certain wavelength, excites the excited state, and forms radicals or ions. Then, a polymer such as a polymerizable prepolymer and a photosensitive monomer is brought into an excited state by energy transfer between molecules, and a charge transfer complex is produced. These complexes continuously crosslink and polymerize to form a film.

The ultraviolet light source is a device that emits ultraviolet light in an ultraviolet curing system. Usually consists of light boxes, lamps, mirrors, power supplies, controllers, and cooling devices. According to the different materials filled in the lamp, they can be divided into metal halide lamps, high-pressure mercury lamps, and odorless lamps. Its performance parameters mainly include: arc length, characteristic spectrum, power, working voltage, operating current and average life.

Although the ultraviolet light source emits mainly ultraviolet light, it is not a single wavelength light but a light in one wavelength band. For different UV light sources, the range of emitted light is different, and the distribution of spectral energy within the band is also different. The ultraviolet light source radiates light in a band, and the energy distribution of light of different wavelengths is not the same. Among them, the energy distribution of light having a wavelength of 300 to 310 nm and 360 to 390 nm is preferable. The wavelength range of the ultraviolet light source is very wide, as shown in Fig. 1, which is divided into three parts, and the effect is best when the wavelength is about 360 mm in the UV-A area.

Figure 1 Spectral distribution

Normal align=left> Second, the composition of UV ink and traditional ink

Normal align=left> The composition of UV inks is similar to traditional inks. The difference is that the film formation of the UV ink is a chemical action, from the monomer to the polymer, while the traditional ink filming is a physical function, the resin is a polymer, and the solvent is a polymer that dissolves the solid polymer into a liquid state. So that the polymer can be printed on the substrate, then the solvent is volatilized or absorbed, so that the liquid polymer can be restored to its original solid state. Table 1 is a comparison of the compositions of the two inks.

table 1 UV ink and traditional composition table