The influence of ink balance and quality in the mo

The influence of water ink balance and quality in lithography

lithography is based on the principle that oil and water are immiscible. The graphic Department of the printing plate can be lipophilic and hydrophobic, and the vacant department can have the selective adsorption of hydrophilic and hydrophobic only by watering first. In addition, offset printing is characterized by indirect printing and color reproduction by means of dot coloring. In offset printing, it is very important to grasp the ink properly, such as the normal transfer of the imprint, the depth of the ink, the correct chromatic registration, and the dryness and dirt of the printed matter. Therefore, whether we can accurately grasp and control the ink balance is the key to ensure the quality of prints. As a skilled printer, you should not only understand the relationship between ink and water balance, but also master the technology and essentials of ink and water balance. Water ink balance refers to adjusting the supply of fountain solution under a certain printing speed and printing pressure, so that the volume proportion of fountain solution contained in the emulsified ink is controlled at 15%~26%, and the slightly formed water in oil (w/o) emulsion ink can compete with the ink on the printing plate with the minimum supply to achieve the "two 100 year" goal

the most important thing in the balance of ink and water is the control of fountain solution and ink. The fountain solution is composed of water and surface functions equal to Falex dry sand/rubber wheel friction tester, which can meet the requirements of ASTM G65 surfactant. The fountain solution can fully wet the layout, has cleaning ability and undisturbed pH value, and ensures that the layout is not dirty

1) function of fountain solution

① form an average water film in the vacant part of the printing plate to prevent the ink on the text from infiltrating into the vacant part and prevent the dirty version

② use the electrolyte in the fountain solution to react with the metal plate base exposed due to wear, which can give full play to its aerodynamic performance, weight and acoustic advantages, and constantly form a new hydrophilic layer to maintain the hydrophilicity of the blank part of the plate

③ control the ink temperature of the layout. Because the speed of the new printing machine is faster and faster, too fast printing speed will increase the temperature of the ink in the high-speed transmission, increase the activity of the ink, and lead to the increase of the dot. Therefore, the high-speed machine puts forward new requirements for the fountain solution, that is, when the fountain solution contacts the inking roller through the layout, it can reduce the temperature of the ink roller and the ink

④ do not enlarge or shrink the text. The fountain solution must have the function of not disordering the relative position of the graphic department and the vacancy Department of the printing plate, so as to ensure that the graphic is neither expanded nor reduced in the whole printing process

inks are generally composed of pigments, fillers, binders and auxiliary additives. When selecting inks, full consideration should be given to the rheological and optical functions of inks

the rheological function of ink is the main basis for judging whether the ink has good printing function. The rheological function of ink mainly depends on the binder of ink. Of course, it can also be properly adjusted by auxiliary additives. The evaluation of ink rheological function can be reflected by the main indicators of ink rheological function, that is, the viscosity, viscosity, thixotropy, yield, viscoelasticity and activity of ink. In actual production, only by grasping these functional indicators can we be familiar with the printing properties of various types of inks, so as to achieve the purpose of selecting inks that meet the printing requirements

the ink and water on the printing plate must exist at the same time to maintain a balance. The purpose is to maintain the maximum ink load in the graphic printing area, so that the ink color is bright, saturated, clear and bright, and to keep the printing area highly clean and tidy. This requires paying attention to the relationship between water supply and ink supply in production

in printing, the ink depth of the print is not only related to the amount of ink in the ink bucket, but also directly affected by the amount of water supply and the balance of water and ink in the layout. When the moisture content of the layout increases, the imprinted ink gradually fades and becomes lighter. On the contrary, reduce the water supply, reduce the moisture of the layout, and the imprinted ink will be relatively darker than the original. Therefore, increasing or decreasing the ink supply and the water supply of the layout will change the depth of the imprinted ink. In the printing process, it should be adjusted according to the actual situation. We should not simply rely on reducing the water supply to improve the ink color. Because the water content is too small, the ink balance will be lost, which is easy to make the vacant Department dirty

however, it is necessary to prevent the practice of flooding with ink. When the water content is excessive and the ink color becomes lighter, we must not ignore the actual situation and mistakenly think that the ink supply is small. Instead of reducing the water supply, we should increase the ink supply frequently. In this way, the ink supply and water supply are increased repeatedly, resulting in vicious cycle, and ultimately all kinds of disadvantages of large water and ink appear, making the printing unable to proceed normally

experienced printers, in actual production, often control the water supply within the smallest possible range under the condition of ensuring that the printing plate will not be dirty, and keep the water supply and ink supply in a relatively undisturbed state, so as to ensure that the ink color of the print is consistent and the printing homework is not disordered. Advocate the practice of small water and thick ink. Here, water refers to the minimum amount of water based on the condition that the vacant Department of the page cannot afford to be dirty; The so-called ink thickness is also based on the hope that the above content will be of little help to you. Large water will cause excessive emulsification of ink, and the ink layer cannot be thick