Overview of the characteristics of the hottest wat

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Overview of the characteristics of water-based inks

the biggest feature of water-based inks is to reduce the emission of VOC (organic volatile matter) into the atmosphere, so as to prevent air pollution, improve the printing environment, and significantly reduce the potential fire hazards. It can completely eliminate the harm of some toxic substances in solvent based ink to human body and the pollution of packaged goods, and improve the overall environmental quality. It is especially suitable for products with high printing performance, such as food, medicine and other products with strict hygienic conditions

water based inks are made of water-soluble resins, advanced pigments, solvents and additives through scientific compound processing and grinding. Water soluble resin mainly plays the role of connecting material in the ink, which is to evenly disperse the pigment particles, make the ink have a certain fluidity, and provide the adhesion with the substrate material, so as to continuously deepen the structural reform of the supply side, and the ink can form a uniform film after printing. The hue in the ink mainly depends on the pigment. The pigment is evenly distributed in the connecting material in the state of particles. The pigment particles can absorb, reflect, refract and transmit light, so they can show a certain color. Generally, pigments are required to have bright color, appropriate coloring power and hiding power, and high dispersion. In addition, it can also have different wear resistance according to different purposes of use. The function of solvent is to dissolve the resin, make the ink have a certain fluidity, transfer smoothly in the printing process, and adjust the viscosity and drying performance of the ink. The solvent of water-based ink is mainly water and a small amount of ethanol

the flexible Chongqing project is of industrial strategic significance. The water-based ink is generally used directly without dilution, and its viscosity range can be 30 ″ -45 ″/25 ℃ (coated with 4 . Gravure water-based ink is usually diluted with ethanol and water 1:1 diluent according to the traditional custom, and the viscosity is generally controlled at 15 ″ -25 ″/25 ℃

the drying of ink is mainly volatile drying and osmotic drying. The drying performance of ink refers to the time required for the ink to dry after being transferred to the substrate, which is also one of the important indicators to measure the quality and performance of ink. Therefore, controlling the drying performance of ink is an important means to achieve good printing effect

the drying speed of flexo water-based ink depends on the printing speed of the printing machine, the drying capacity of the drying equipment, the material performance of the substrate from January to November this year, and the composition of the ink itself. The general principle of selecting the ink drying speed is that under the existing conditions of the printing machine, the ink should be able to be fully dried before the next printing color deck and before rewinding or stacking, but it cannot be dried on the printing plate. If the ink dries too fast, it will dry and gradually accumulate on the printing plate and the embossing roller, and may block the embossing roller, resulting in the loss or damage of halftone points, and white leakage in the field part; If the drying speed of the ink is too slow, there will be a printing smell, or in the case of multi-color overprint, it will cause the back to stick dirty

in fact, the viscosity and pH value of the ink will also have a certain impact on the drying performance of the ink. For example, if the viscosity is too high, the drying speed of the ink will be reduced, and if the pH value is too low, the drying speed of the ink will be too fast. Therefore, in the printing process, we should first adjust and control the viscosity and pH value of water-based ink, and then add an appropriate amount of fast drying agent or slow drying agent to the ink according to the actual printing speed to adjust the drying speed of water-based ink

the fineness of water-based ink refers to the size of pigment particles in the ink and the uniformity of their dispersion in the binder. It is also a very important quality indicator. The fineness of the ink will not only have a certain impact on the coloring power and color equality of the ink, but also affect the rheology of the ink. If the ink particles are too thick, it is easy to cause hairiness on the edge of the starting point, paste version and other defects; However, if the ink particles are too fine, the fluidity of the ink is too large, which will cause dot expansion, which is bound to affect the quality of the printed matter

the commonly used additives in water-based ink mainly include: pH stabilizer, slow drying agent, defoamer, diluent, etc

(1) pH stabilizer. PH stabilizer is mainly used to adjust and control the pH value of water-based ink to make it stable at 8 At the same time, it can also adjust the viscosity of water-based ink and dilute the ink. Generally speaking, an appropriate amount of pH stabilizer should be added every certain time in the printing process to keep the water-based ink in good printing condition

(2) slow drying agent. Slow drying agent can inhibit and slow down the drying speed of water-based ink, prevent the ink from drying on the printing plate or roller, and reduce the incidence of printing failures such as blocking and pasting. Control the amount of slow drying agent, which should generally be controlled between 1% and 2% of the total ink volume. If the amount is too much and the ink is not completely dried, the printed matter will stick dirty or produce peculiar smell

(3) defoamer. The function of defoamer is to inhibit and eliminate the generation of bubbles. Generally speaking, when the viscosity of water-based ink is too high, the pH value is too low, or when the printing machine runs faster, it is easy to produce bubbles. If the amount of bubbles is relatively large, there will be white leakage and uneven ink color, which will inevitably affect the quality of printed matter

water based inks comply with the requirements of environmental protection. The products are non-toxic, non corrosive, non irritating odor, non combustible, non explosive, good safety, convenient transportation, high concentration, low dosage, low viscosity, good printing adaptability, stable performance, good adhesion fastness, fast drying, excellent water, alkali and abrasion resistance after drying; It is easy to adjust the operation before and after printing and during the printing process. After printing, the printed matter appears full of impressions, bright colors, high gloss, gorgeous and rich. The printed complex patterns can also reach a rich level, and can print bright and high gloss colors

reprinted from: Zhonghua printing and packaging

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