The binder in the ink is a liquid phase dispersion medium. Some of the inks are not oily, so they are called toners or carriers. The binder is a carrier for pigments and fillers and must therefore have a certain viscosity. After the binder has been transferred from the plate to the surface of the substrate, it must be fastened to the pigment quickly, and the conjunctiva further dried. This has high gloss and abrasion resistance. The rheology, viscosity, viscosity, drying speed and the like of the ink mainly depend on the binder. Different types of inks can be prepared using different characteristics of the binder. There are generally the following types of binders.
1 Infiltrated fixing material
This kind of connecting material is generally used in rotary presses and letterpress printers to print newspapers or books. It is a kind of non-dry mineral oil. Its drying mechanism is the penetration and absorption of paper. It mainly uses mineral oil, carbon black, asphalt, or pine resin type dry connection materials to dry faster, thus overcoming the drying time of oil-based connection materials. Long, easy to emulsify with water and lack of light after conjunctiva and other shortcomings. Therefore, China successfully developed bright offset inks and resin-based quick-drying offset printing inks in the 1960s. Later, on this basis, it was improved to fast-fixed offset printing inks, and the quality was significantly improved.
In the resin type binder, the high molecular weight resin is first dissolved in a dry vegetable oil to form a high viscosity phase, and the mineral oil and the high boiling kerosene are used as a low viscosity phase to dilute the binder to an appropriate viscosity. When the ink made of the resin binder and the pigment is printed on the surface of the paper, the low-viscosity binder is immediately selected for absorption, leaving the binder of the high-viscosity phase and the pigment together on the surface of the paper, the ink is immediately fixed, and the oxidized conjunctiva The effect of forming a bright film.
2 volatile binder
Typical volatile inks include benzene type gravure inks, alcohol type and solvent type flexo inks, volatile dry screen inks, and the like. The binders they use are made by dissolving suitable resins in various solvents and stirring them thoroughly.
3 reactive binders
This kind of ink develops later, and the chemical components contained in the connecting material can react under the light, heat radiation or other conditions to form a film and fix it on the surface of the substrate. At present, UV curable inks, ie, UV inks, are commonly used as the linking material, which is a monomer having cross-linking, polymerization, and curing effects. When the photoinitiator is present, it is irradiated with ultraviolet rays and can be cured in about 1 to 5 seconds. (Author: Luan Cunfu)