The hottest temperature and humidity and ink chara

Temperature, humidity and ink characteristics

ink is one of the important materials in printing production, and its characteristics largely determine the printing quality of products. However, in addition to the inherent conditions of its components, the changes of temperature and humidity also affect the characteristics of ink, which has been fully proved by the production process practice. We know that the interaction between printing paper and ink is based on the form of adhesion and adsorption. This feature shows that factors such as the adhesion, cohesion and brightness of ink greatly affect the printing quality of products. The temperature change of the production environment directly affects the viscosity and cohesion of the ink. In the practice of printing production, we can find that when the temperature of the printing environment is too low, the molecular movement of the ink binder is slow, and the ink is easy to be solidified, so its cohesion is large, and the fluidity of the ink is poor. In the printing process, there will be poor ink transmission and uneven ink distribution, which will affect the uniformity of the coating of the printing ink layer. On the other hand, due to the cohesion of the ink, its consistency is correspondingly large. The viscosity of ink with high consistency is obviously large, so it is very easy to cause defects such as paper powder, paper wool and coating layer pulling off the paper surface in the printing process, and cause chain printing quality failures such as plate pasting, printing fuzzing and thickening. If the temperature is too high, the ink will become thin, the coloring power will decline, the ink color of the print will appear weak, the color is not bright, and the printing quality will decline

in addition to the influence of the temperature of the production environment on the characteristics of the ink, the printing speed of the machine will also affect the characteristics of the ink. This is because the ink has the characteristics of "thixotropy". When the printing machine is running at high speed, the friction coefficient of each ink roller (including the ink bucket iron roller) when it rotates at high speed is large. With the development of sensor technology, the heat generated by the roller body can dilute the ink, increase the fluidity and significantly reduce the coloring force. Based on this situation, we should give full consideration to the first when allocating ink: see the printing speed of the machine used, and reasonably adjust the thickness of the ink, so as to better ensure the quality of printing ink. Obviously, only maintaining an appropriate and constant temperature is an effective measure to prevent the ink consistency and viscosity change of oil fly ash as a solid waste after coal combustion. In addition to the influence of the above conditions, there are also operational factors that cause the change of printing temperature, such as the appropriateness of the adjustment of ink roller and pad pressure, which are often ignored by operators who lack production experience. According to the author's previous process practice experience, the contact pressure between the rubber roller and the inking iron roller is too tight, the relief plate pad is too high, resulting in too tight contact with the inking roller, and the gap between the ink bucket steel plate and the iron roller is adjusted too small, so that the rotation stroke of the ink bucket iron roller is too large, which will greatly increase the friction heat of the printing brush and increase the ink thinning and fluidity. Therefore, in order to reduce the temperature rise caused by abnormal friction and reduce the chance of ink variation, the rubber roller body must maintain a good degree of roundness. If the roller head and bearing are worn or damaged, they should be repaired in time to maintain a uniform and appropriate contact pressure between the rubber roller and the inking iron roller. A 0.05mm thick plug gauge can be used on the production site to check whether the contact is appropriate, That is, insert the plug gauge between the rubber roller and the inking iron roller for pulling, with a slight sense of resistance. The adjustment of the printing plate height cannot be significantly higher than the technical parameters of the equipment specification, so that it can maintain a uniform and appropriate contact condition with the inking roller. If the layout is not large, do not adjust the rotation stroke of the ink bucket iron roller to "maximize" for ink delivery. Through the control of these operation techniques, we can better prevent the abnormal temperature rise during machine printing and ensure the stability of ink characteristics

from the above situation, it can be seen that the influence of temperature on ink is mainly manifested in that it can change the thinness, fluidity and coloring power of ink. The influence of humidity on ink performance is reflected in the dryness of imprinting. The production process shows that the high humidity of the printing environment provides us with great convenience, and the ink layer dries slowly. On the contrary, if the environmental humidity is low, the printing ink layer will dry faster. Because the air humidity of the printing environment is high, and the moisture content of the printing paper is also high, these will be one of the reasons that affect the drying of the ink layer. Here, when the ambient temperature is between 20 ~ 25 ℃, the relative humidity is 65% and 75% respectively. The printing results of the two production conditions show that the drying speed of their ink layers is up to 1 ~ 2 times different. It can be seen that the influence of temperature on the ink is greater than that of temperature. Therefore, it is particularly important to do a good job in the humidity control of the production site

in view of the impact of temperature and humidity changes in the production environment on the ink and printing, in the absence of air-conditioning equipment, to reduce the impact of temperature and humidity changes on the ink and ensure the ink quality of color printing and the accuracy of overprint, the best measure is to place the prepared ink at a temperature between 20 ℃ and 25 ℃ a few days before printing, so that the ink can be balanced at the temperature and humidity suitable for printing conditions for a period of time, The printing thixotropy of ink is controlled within the scope of "minimization", so as to improve the printing quality and process effect of products

to sum up, it is of great significance to correctly understand the impact of temperature and humidity changes on the characteristics of ink and take corresponding process and operation technical measures to control, so as to effectively avoid the main blindness in production, prevent the occurrence of various quality problems or ills, and improve the quality of products

reprinted from: Printed world by Kang qilai