Drying technology for the most popular printing pr

2022-07-30
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Drying technology for printing press

the drying process includes all processes after ink transfer. In these processes, ink curing is the primary condition for post press processing and the premise for the use of printed matter in daily life. According to the composition of ink, drying methods can be divided into physical drying, chemical drying, and the comprehensive application of these two methods. Different inks and varnishes require different drying systems or the comprehensive application of several drying systems to obtain the best drying effect. If an infrared and ultraviolet drying system is installed on a printing machine, it can basically meet the needs of all printing activities, so it is very useful

in consideration of its drying performance, the composition of printing ink should meet the following two contradictory requirements: first, when the printing machine is printing or stopped for a short time, the ink cannot dry on the ink roller; First, after printing, the ink on the substrate needs to be quickly dried and fixed

several most important factors affecting the drying performance of ink: ① ink composition (ink pigments, binders and related additives); ② Properties of substrate materials (such as permeability); ③ Printing conditions (ink transfer amount, receiving stack height, printing speed); ④ Climatic conditions (indoor temperature and humidity); ⑤ Composition of drying system (such as air flow on the ink surface, reaction time, type of energy supplied, etc.). Temperature is a decisive factor. Generally speaking, the higher the temperature, the better. Because the higher the temperature, the faster the ink polymerization speed, the smaller the ink viscosity, the more conducive to penetration, and the faster the solvent evaporation

understand the causes of printing static electricity and master the correct Countermeasures

during the printing process, sometimes the paper or printed matter will adhere to each other, as if the paper has a strong vacuum suction, which is difficult to separate. This phenomenon is printing static electricity. In winter when the climate is dry, the static electricity of printing paper is particularly prominent, which may cause obstacles to paper feeding, paper receiving and paper leveling, or may cause automatic paper feeding or frequent adverse consequences such as double sheet, empty sheet, disordered paper receiving and increased loss, which not only reduces the production efficiency but also affects the product quality. Therefore, it is of the positive significance to correctly understand printing static electricity and master corresponding methods to promote production

when the water content of paper is high, it can become the conductor of electricity; On the contrary, when the water content is very low, it is absolute, and the paper is prone to static electricity. First, the papermaking process is not suitable. That is, in the process of paper making, due to the low content of electrolytes (alum, sodium chloride, etc.) and the excessive content of sizing substances (high collar soil, etc.), the paper is affected by high temperature and pressure during drying and calendering, resulting in high-voltage static electricity on the paper. Second, the paper is stored improperly. For example, when there is a great difference between the temperature of the paper cart and that of the printing workshop, the paper does not have a very large expansion change due to the variation of the moisture content, which will affect the registration, and it is easy to cause static electricity, which will bring inconvenience to the brush guide. In addition, the placing time of the paper before printing is too short, or the stacking time is too high, resulting in the lack of effective balance time between the paper and the printing ambient temperature, resulting in static electricity on the paper. Third, printing friction causes static electricity. When the water content of the paper is obviously low, the paper large-size zigzag stress corrosion testing machine will be excessively dry under the electronic loading condition. During the printing process, due to the friction and pressure of paper feeding and embossing, the electrons outside the nucleus of the paper will gain or lose, making the paper electrostatic

the paper has static electricity, and the situation is different. It is caused by one cause, but also by several adverse conditions. All kinds of paper, even the same kind of paper, have different static electricity levels between this batch and the previous batch, that is to say, there will be differences in the level of dynamic resistance monitoring system designed for voltage. Another feature is that the paper is static and cooperates with domestic and foreign automobile enterprises to expand the new energy vehicle market. The electricity properties of both sides are opposite, When printing paper "It is consistent that the front and back sides of the purified water bottle can be recycled and stacked, that is, the front side is up or the back side is up. Therefore, the paper with the front and back sides in contact is firmly adsorbed to each other, which is not easy to be separated, which brings certain obstacles to the printing paper feeding, transmission and paper leveling.

to prevent the occurrence of printing static electricity, we must first control the source. The use of paper with static electricity can be postponed, the storage time can be appropriately extended, and the paper warehouse should be well controlled The temperature and humidity of the paper are controlled between 18 ℃ and 20 ℃, and the relative humidity of the air is controlled between%, which is conducive to weakening or eliminating the static electricity of the paper. Secondly, the paper is dried to remove static electricity. When the paper is in urgent use, the paper dryer can be used to hang the paper with static electricity. Pay attention to the coordination between the machine speed and air humidity during hanging, that is, when the machine speed is fast, the relative temperature of the ambient air is controlled at%, on the contrary, when the machine speed is slow, the air temperature is maintained at%. It should be noted that the thickness of each stack of paper should be within 10mm when hanging. Third, remove static electricity by emergency paper drying. If there is static electricity on the cut paper during printing, the steam method can be used to quickly dry the paper to reduce the static electricity of the paper and complete the printing as soon as possible

comprehensive elimination methods can also be used to eliminate paper static electricity, that is, the combination of increasing paper temperature and water content and Using Static Eliminators will have better results. The method is as follows:

1. Install air conditioning equipment in the printing workshop, and adjust or maintain the temperature and humidity of the printing workshop according to the strength of paper static electricity. Generally, the workshop temperature is adjusted between 18 ℃ -20 ℃, and the relative air temperature is maintained between%. If the paper is seriously charged, the relative humidity of the air can be adjusted to% or less

2. Install the electrostatic eliminator on the printing machine. Eliminate the paper static electricity by adjusting the voltage or high frequency. If the paper static electricity is large, use high voltage or high frequency. If the static electricity is not large, turn down the voltage and high frequency

3. Eliminate printing static electricity with isotope emitter. The principle of isotope radiation is basically the same as that of electrostatic eliminator. Both of them ionize various molecules in the air into ions. Because the ions have different electrical properties, they become good conductors of electricity. When the paper passes through the ion space, part of the static electricity is neutralized and the other part is taken away by air ions, so as to achieve the purpose of eliminating static electricity

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