Electron beam curing ink (EB ink) is an ink that can rapidly change from a liquid to a solid state under the irradiation of a high-energy electron beam. It is a new environmentally-friendly ink. The main advantage of EB ink is that it does not pollute the environment. Its components also do not contain harmful organic volatile substances. It has low operating costs, high production efficiency, low energy consumption, stable printing quality, good reproducibility, and high print glossiness. Feeling strong.
Composition of 1 EB ink
The composition of EB ink is similar to that of general ink, and is mainly composed of pigments, binders, auxiliary agents and the like.
Pigments are the color materials of inks. The quality of the ink determines the quality of the ink. The following principles should be observed in the selection of pigments: 1) Since it is mainly used for food packaging, the selection of pigments must first be non-toxic. 2) In addition, since the ink is dried using a high-energy electron beam, the color of the pigment should not change under the electron beam irradiation. 3) The pigment concentration should be high and the color should be bright. It must have excellent dispersion and sufficient coloring power. 4) The ink cannot be gelled within the effective storage period after the pigments are mixed. 5) When the pigments are used together, the amount of each pigment in the ink must be accurate.
In the selection of binders, EB inks have special requirements. The main components are acrylic resins and reactive monomers involved in the reaction.
The properties of the prepolymer (low molecular weight polymer containing unsaturated functional groups) used in the EB ink determine the physical properties of the ink after curing, such as abrasion resistance, adhesion, elasticity, hardness, chemical resistance, solvent resistance, and The color difference of pigments and other properties. Inks prepared from different prepolymers exhibit different physical properties. The prepolymer used in the EB ink is generally an acrylic oligomer with good fluidity. Common prepolymers include epoxy acrylic resins, polyester acrylic resins, acrylic polyurethanes, chlorinated polyester acrylic resins, and the like.
Reactive diluent monomer is used in the EB ink vehicle. The role of the reactive diluent in the ink is: 1) to adjust the viscosity of the high viscosity prepolymer. 2) Adjust the ink adhesion. 3) Strengthen the ink film strength. 4) Accelerate curing speed. There are many types of reactive diluent monomers. In general, reactive diluents can be divided into three categories: monofunctional, bifunctional, and multifunctional reactive diluents. In actual production, EB inks generally use a variety of monomer combinations have been able to obtain satisfactory curing speed, viscosity, adhesion, elasticity, hardness, impact strength, solvent resistance and other properties.
2 Curing mechanism
The curing mechanism of EB inks is basically similar to that of UV inks, except that EB inks do not require photoinitiators. The specific drying mechanism can be described as follows: Acrylic resins have a high degree of unsaturation. When they are exposed to high-energy electron beams, the molecules change from the ground state to the excited state, and unsaturated double bonds are opened to generate free radicals or ions. Then, by the initiation of the free radicals, a growing polymerization reaction of the chain occurs, crosslinking polymerization occurs between the oligomer and the monomer molecules, a network-like polymer is formed, and the ink rapidly cures the conjunctiva. Throughout the drying process, the role of electron radiation is like a special initiator. Its main role is in the initiation phase of the chain. Once the polymerization begins, the reaction is normal to the polymerization reaction as the reaction of each step is independent of the radiation. Learn the law. The whole process can be completed instantaneously under the irradiation of the electron beam, so the drying speed of the EB ink is particularly fast, and curing is usually completed in 1/200 second.
3 EB ink advantages
From the above curing mechanism, it can be known that the EB ink has many advantages over the general ink, specifically in five aspects.
1) Environmental protection and safety. From the EB ink composition point of view, EB ink does not contain harmful organic volatiles, its components do not contain solvents, no pollution to the environment, packaging, print odor smaller than the use of UV inks. Since the ink does not contain VOCs, the damage to workers is minimal. At present, the application of EB ink in food packaging and printing is very promising.