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The difference between printing ink and offset ink composition

Time: 2022-08-12 Hits: 40

 

Ink is an important material for book printing, which expresses patterns and characters on the substrate by printing or inkjet. The ink includes main components and auxiliary components, which are uniformly mixed and rolled repeatedly to form a viscous colloidal fluid. It consists of binders (resins), pigments, fillers, additives and solvents. For books printing, packaging printing and decoration, architectural decoration and electronic circuit boards and other printing project. With the increase of social demand, the variety and output of ink also expand and grow accordingly.

 

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Printing ink is composed of several components such as binders, fillers, colorants and auxiliaries. When preparing, it is mixed and stirred according to a certain proportion according to the requirements of printing, and is made by rolling and rolling ink process. Printing ink is a colloid with a complex structure, which is formed by uniformly dispersing solid particles such as pigments with a particle size of about 0.1 microns in a binder. Pigments include inorganic pigments and organic pigments. The components of inorganic pigments may be inorganic elements, metal oxides or inorganic salts.

Such as carbon black, titanium dioxide, chrome green, etc. Inorganic pigments are characterized by stable chemical properties, strong light resistance and heat resistance, but their disadvantage is poor tinting strength; while organic pigments are synthetic organic compounds with many bright colors and suitable for printing. The advantage of strong resistance is that it has poor light resistance and heat resistance. At present, the black pigments used in printing inks are mostly inorganic, while the color inks are mostly organic pigments.


Commonly used binders for offset printing inks are vegetable oil type and solvent oil type. Vegetable oils such as linseed oil, tung oil, dehydrated castor oil and other dry vegetable oils containing unsaturated double bond structure; solvent oils such as motor oil kerosene and other non-drying mineral oils, volatile oils such as benzene, xylene, methanol, ethanol, isopropanol, etc. organic solvent. In addition, natural resins such as rosin and asphalt, and synthetic resins such as phenolic resins and polyamide resins are also used as binders.

 

The additives used in offset printing ink mainly include linseed oil to adjust ink viscosity, brightener to increase ink gloss, and drier to promote ink drying. The types of driers include fatty acid, naphthoic acid, cobalt, manganese, and aluminum salts of octanoic acid. These salts can be oxidized by oxygen in the air, and the oxidative property of the metal ions increases after the valence increases, which can promote the oxidative polymerization reaction of drying oil, so these additives can catalyze the film-forming reaction of oxidative polymerization and cross-linking of drying oil. effect. In addition, some inks also contain fillers such as colloidal calcium carbonate.

 

With the advancement of human civilization and the development of the printing industry, the substrate materials are constantly being developed and expanded, and the printing methods are constantly being introduced. The production process of ink is more sophisticated, and the types and colors of ink products are constantly increasing. For example, the promotion of waterless offset printing technology has increased the demand for waterless offset printing inks, and the rise of flexible digital printing has also brought digital printing inks to the stage of history. There is also a strong voice for green environmental protection, which has set off the re-selection of ink raw materials and the reform of manufacturing processes, such as water-based inks, soybean-based offset printing inks, UV inks, and FB inks. Ink, the largest source of pollution in the printing industry, is working hard to reduce the volatilization of its organic compounds and the application of harmful metals. We have reason to believe that the development of the ink industry in the future will move forward in the general direction of caring for life, embracing nature and harmonious society.