In plastic gravure printing, the transfer of pigment is a difficult problem, especially for the bright tone part of printed matter, which is more troublesome in the printing process. But as long as we do the following work well, the problem can be solved.
First of all, the quality of the ink determines the effect of pigment transfer. If the ink in the rolling process, the more rolling times, the more adequate grinding, the finer the pigment, and at the same time, the more evenly dispersed in the binder, that is to say, the smaller the fineness of the ink, which is corresponding to lay the necessary foundation for the bright tone part of the printed products. If the ink fineness is poor, it is easy to produce dot vacancy At the same time, the selected resin in the ink should have the characteristics of good printability, good dispersion and stability of pigment, good adhesion with substrate material, good solubility of solvent and good separation of solvent after printing. With these characteristics, the resin and solvent together, give the ink the necessary fluidity, which is conducive to the wetting and dispersion of pigments, so as to improve the adhesion of ink. In order to improve the softness and adhesion of ink, appropriate auxiliary agent should be added into the ink. Of course, improper selection or excessive addition of auxiliary agent will also reduce the adhesion of the ink. Therefore, the selection of raw materials, raw materials, raw materials, etc Component composition, processing degree and method directly affect the quality of ink. The selection of high-quality ink is the prerequisite for pigment transfer.
With high-quality ink, then is how to make the ink smoothly into the mesh, and in the role of scraper, cots, and smoothly from the mesh, and firmly transferred to the substrate.
We know that the role of solvents is to dissolve and dilute resins, pigments, additives and additives, etc., to give fluidity, make pigments wettable and easy to disperse. If the printing ink viscosity is too high, the whole ink system will be in a saturated state, and the fluidity and wettability of pigments and other substances will be poor, and they will not disperse evenly. Instead, they will appear in groups and will be easy to pile up together. In this way, the pigments will not be able to enter the mesh smoothly when the printing viscosity is too high, let alone transfer The so-called blocking phenomenon. Therefore, as long as the colloidal system composed of resin and pigment in organic solvent is not in supersaturated state, but in saturated or unsaturated state, so that pigment and other substances can be well dispersed in it to form a uniform and fine colloidal system, so that the pigment can enter and leave the mesh smoothly. Of course, the viscosity of ink printing should not be too small to avoid the occurrence of dot vacancy or partial vacancy. At the same time, resin is the main material to make the pigment firmly adhere to the plastic. Therefore, if the ink printing viscosity is too small, the transfer of pigment will also be affected. Practice has proved that within a certain range of ink printing viscosity (15-24 seconds, using chaen viscosity cup No. 3), the greater the ink printing viscosity, the worse the effect of pigment transfer. In order to ensure the good transfer effect, the ink printing viscosity is generally found in 11-18 seconds (chaen viscosity cup No. 3).
In the slow printing machine (printing speed is less than 80mm / min), we usually use medium and slow drying solvent to dilute the ink, so as to avoid the ink drying too fast and the ink in the fine mesh of the plate will dry and block the plate, and the pigment will not transfer to the substrate.
In addition to the electrostatic component of the printing agent, we need to avoid the phenomenon of electrostatic transfer when using the electrostatic agent Good performance of pigment transfer.
When there is a transition between light and shade of printed matter, usually select the dark part, and then print the bright part (that is, from dark to light printing). The text part of the cylinder is covered with a lot of mesh lines, the purpose is to scrape the ink blade in the ink, graphics and text part of the ink is not taken away. Here, we print from dark to light. In fact, we also have similar principles and purposes, all for the maximum reproduction of the graphic part. At the same time, in high-speed printing (printing speed is above 160m / min), due to the high-speed rotation of the cylinder, there will be a certain amount of air flow from the separation of the scraper and the cylinder to the position of the substrate and the cylinder. If we print from dark to light, we can avoid the impact of air flow on the light part.
In the soft and hard performance of cots, if you choose soft cots, it will help to transfer pigment.
The quality of the printing plate also has an impact on the transfer of pigments. If the plate corrosion is not good, the mesh is rough, or the burr generated during grinding is not removed, it will hinder the transfer of ink.

If the printing environment temperature is too low, it will affect the stability, dispersion and fluidity of the resin, that is to say, it will affect the stability and even dispersion of the pigment, and the pigment transfer effect will become worse. Therefore, it is necessary to maintain the normal printing environment temperature.

Finally, we should pay attention to the following issues: whether the nature of the printed matter is consistent with the ink, whether the surface treatment of the substrate meets the requirements, whether the substrate is hygroscopic, avoid the mixing of different inks, and maintain normal printing environment humidity, because these also have certain impact on the transfer of pigments.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.

The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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