First, the classification of printing ink:
Many types of inks have different physical properties, some are very thick, some are sticky, and others are quite thin. Its composition can be divided into three parts: the liquid component is called the binder; the solid component is called pigment (pigment or dye) and various additives. Different inks have different drying methods: different printing processes use different inks; different substrates use different inks.
1, according to different drying methods can be divided into:
1) Oxidation conjunctiva drying ink, 2) Osmotic drying ink, 3) Volatile drying ink, 4) Radiation drying ink, 5) Wet coagulation drying ink, 6) Condensation drying ink, 7) Precipitation drying ink 8) Two-component reaction drying ink, 9) Gelatinized drying ink, 10) Filtration drying ink, 11) Dry type ink combined by various methods.
2, according to the printing process classification:
1) Lithographic Printing Inks: Lithographic printing inks (referred to as plain printing inks) are sticky and sticky inks. Most of them are oxidized conjunctiva dry inks, which must have good water resistance. Can be divided into sheetfed ink and web ink, the former mostly fast-drying oxide conjunctiva ink, the latter mainly to osmotic drying.
2), letterpress printing ink (abbreviated letter printing ink): It is a kind of sticky ink, its sticky change scope is very big, and presses the printing speed. Its drying methods include several methods such as osmotic drying, oxidative conjunctiva drying, volatile drying, or a combination of several drying methods. Embossing inks have rotary printing inks, thermosetting inks, news inks, and the like.
3) Flexographic printing ink: It is a very dilute ink. From the perspective of rheology, it is the closest ink to Newtonian fluids. The drying of the ink is mainly accomplished by the evaporation of the solvent, and some of the drying on the paper is due to the penetration of the ink into the paper. The ink can be divided into alcohol type, mixed type and water type.
4) Intaglio printing ink (referred to as gravure printing ink): can be divided into two major categories, one is gravure ink, the other is engraving gravure ink. The former is a very dilute fluid with a very low viscosity. It completely depends on the volatilization and drying of solvents. It is a kind of volatile drying ink and can be printed on non-absorbent substrates. The latter has a high viscosity and a relatively large yield value. With greasy nature, basically rely on oxidative conjunctiva drying.
5), stencil printing ink: requires good fluidity, low viscosity, low viscosity, fast through the mesh, after the transfer to the surface of the absorbent substrate can quickly penetrate dry, there should be a good attachment on the non-absorbable substrate surface Focus on. The drying methods are as follows: volatile drying type, oxidative polymerization type, permeation drying type, two-component reaction type, ultraviolet drying type and the like.
3, different printing materials on the ink requirements:
1)
Newsprint: Embossing inks for newsprint printing are very thin, low-viscosity, and very fluid inks, and their fluidity depends on the speed of the printer. It is dry completely absorbing osmotic drying. Today press printing has been replaced by letterpress printing as offset printing. Flexo printing has also been used in news printing. Water-based inks have been used extensively in flexo printing.
2), coated paper and surface treated paper: For embossing and sheetfed offset printing, the thickness of the ink printed on the coated paper should be thicker than the uncoated paper, the ink viscosity should be a little larger, and the ink should be finally dried. It is mainly realized by oxidized conjunctiva; when the rotary machine is printing on the coated paper, it is required to use the fast-drying ink, and the oxidized conjunctiva dried ink is gradually replaced by the thermosetting ink.
3) Non-coated paper: The quality of non-coated paper varies, and the ink used must also meet the requirements of various papers. It is usually printed with viscous ink, but is thinner than the ink used for coated paper. The drying method is based on penetration absorption and oxidized conjunctiva.
4) Cardboard: Cardboard is usually used for carton, carton, print packaging, hardcover cover, etc. In printing, the ink requires good fluidity, little stickiness, and can withstand the impact of mechanical forces such as collisions and ink pick-ups during handling. Printing on paperboard can use all printing methods: dry embossing or offset printing of oxidized conjunctivas, infiltration and evaporation of dried gravure or flexographic printing.
5), other paper:
Second, the main components of printing ink:
The printing ink is a paste colloid that is uniformly dispersed and mixed with materials such as colorants, binders, and fillers. The color material gives the print a rich and colorful hue; the binder serves as a carrier for the color material and also serves as a binder to fix the color material on the surface of the substrate; the filler gives the ink an appropriate property so that the ink can satisfy the printability of various printing processes. .
The ink should have a certain degree of fluidity, and meet the required properties of various printing processes. It can quickly dry on the prints. The dried ink film should have a variety of water, acid, alkali, light, and rub resistance. Wear resistance and other resistance.
1, the connection material
The binder is an adhesive-like fluid. Its role is first as a carrier of pigments, and solid particles such as powdery pigments are mixed and connected; secondly, as a binder, the pigments can finally be fixed on the surface of the substrate. To achieve the display of text, images, marks, decorations and other purposes. The binder material largely determines the viscosity, viscosity, dryness, and fluidity of the ink. To get high quality inks, you must use high quality binders. The main components of the binder are oil (vegetable oil, mineral oil), resins, solvents, and auxiliary materials.
2, additives
Due to the variety of printing conditions, at the same time, in order to enable printers to actively adapt to changing printing conditions, the use of good inks to improve the quality of printing, it is inevitable to add several ink additives with specific properties. Ink additives can improve certain properties of the ink, such as: plasticizer can increase the plasticity of polymer materials, so that the ink film has better flexibility; thinner can make the ink thinning, increase the fluidity of the ink, while reducing Viscosity of ink; detackification agent, also known as viscosity reducer, it can reduce the viscosity of ink, and does not affect the body of ink; driers (desiccants) can accelerate the drying speed of ink; the purpose of use of diluting agent is to dilute the The color of the ink, also known as the lightening agent; the purpose of the anti-gelling agent is to prevent the gel from gelling, thickening, and blocking; the anti-drying agent (antioxidant) can retard the oxidative polymerization process of the dry oil; anti-dirty agent ( Anti-fouling agent) can prevent the ink on the printed product from smudging to the back of another printed product; the surfactant can increase the dispersibility of the solid component and prevent it from agglutination and precipitation; the preservative can prolong the storage time of the water-based ink; The agent can eliminate air bubbles generated during the use of the ink; the UV absorber can improve the light fastness of the print.
3, pigments and dyes
The colored materials used in printing inks are usually pigments and also have some dyes. Pigments and dyes are very fine colored substances. Pigments are generally insoluble in water and insoluble in the binder. Most of the solution is called suspended state; the dye is generally soluble in the binder. Pigments must have high coloring power, hiding power, chemical stability, light resistance, and the like, and at the same time have high dispersibility in the binder. Commonly used in printing inks are inorganic pigments, fillers, organic dyes, and dyes.
Source: Ke Yin Network