In the offset printing process, the ink used is often adjusted for its suitability. To adapt to the printing needs of different products and different papers. Adaptability of the ink. This is achieved by adding suitable auxiliary materials to the ink. Because people have different understandings or prejudices of auxiliary materials, therefore. In actual production, it is likely to enter some "misunderstandings" and produce unsatisfactory results.
First, completely replace the varnish with de-adhesive
In the process of printing a large-area field version, when the ink is not easy to be evenly dispersed during the transfer of the ink roller, or when paper “linting†or rough printing occurs, the ink viscosity is generally too high.
The main ingredient of the dissolving agent is aluminum stearate, which is a kind of wax. Its role in the ink is to reduce the cohesion of the ink. The main component of the oil-reducing oil (we mainly use the No. 6 oil) is dry. Vegetable oil, its main role is to improve the flow of ink and reduce the viscosity of the ink. Detackifiers and varnish can reduce the viscosity of inks, but their properties are not exactly the same. The detackifying agent also has the effect of suppressing ink drying while reducing the viscosity of the ink and the property of reducing the adhesion of the ink layer to the paper. In the ink, the varnish oil can reduce the viscosity of the ink and increase the ink flowability. Although the ink layer drying speed may have an impact, it is not obvious. If an excessive amount of detackifying agent is added to the ink to reduce the viscosity of the ink, the ink may be over-emulsified, and the phenomenon that the imprint is not dry or loose and the ink is flying may be caused, and the effects on polishing, laminating, and other post-processing may be extremely affected. serious. Therefore, do not use as much as possible, if you need to use 6 # adjustable varnish instead, and pay attention to the amount added, do not exceed 3%, and at the same time increase the amount of desiccant.
Second, using white ink as a diluting agent
Individual color inks need to add a diluting agent to the original ink to make it a light color ink, and this diluting agent should have colorless and transparent properties. Both the bright paste and Viely oil are ideal crushing agents. It has the effect of not changing the original ink color but changing the depth of the original ink. If white ink is used as a diluting agent. It is wrong. Because the white ink has a white hue, it changes the hue of the original ink so that the original ink tends to white and tender jade ink rather than lighter ink. This is contrary to the intent of the operator to require light-colored ink. And in the offset printing process. If too much white ink composition of the ink, the white ink because pigment particles than the major, in the ink delivery process will take place pigment particles piled on the plate or blanket. Causes the roughness of the imprint.
Third, do not distinguish between the different effects of the detackifier and detackifier
Adding an anti-adhesive agent to the ink can prevent or reduce the problem of stickiness on the front and back of the printed paper. The detackifier is to reduce the viscosity of the ink, and it mainly plays its role in the transfer of ink during printing. If you confuse the two without distinction, it is likely that other problems will arise.
If the detackifying agent is added to the ink in order to prevent the ink on the front and back of the sheet from sticking, the "non-dry" nature of the de-bonding agent will prolong the drying time of the ink layer of the ink and will adversely make the surface of the sheet more sticky.
on the other hand. If more detackifying agents are added in order to reduce the viscosity of the ink during the printing process, it not only does not function well as a viscosity-reducing agent. It will also "roughen" the ink. To make it lose its luster and affect the quality of the product.
Fourth, do not pay attention to the difference between red and white oil
Red dry oil (also known as drilling dry oil) and white dry oil (also known as dry oil) are all desiccants for ink, but due to the composition of the two components are different. It is also different from the dry form of the ink layer.
The addition of red dry oil to the ink can accelerate the rate of oxidative conjunctiva on the surface of the ink layer, that is, it quickly dries on the surface of the ink layer. However, red dry oil can not promote the ink layer inside the dry operation speed has greatly improved. White operating oil promote overall ink drying performance, when added to the ink dry white oil, and an inner surface of the ink drying speed can be greatly improved. therefore. When we use desiccant. Must pay attention to the difference between the two forms of drying. E.g. For the ink surface drying. Red dry oil is better than white dry oil.
However, if the thick printing ink layer or the paper on the ground due to pH relationship itself is not good drying performance of the ink layer, if the operator simply use red oil as the ink drying Jing, the ink layer is likely to appear The surface is dry but the interior is not very dry. Such printed materials, in the case of the event of force rub, it is easy to wipe off the ink left the prints were rubbed marks affect product quality.
In addition, it is necessary to add a desiccant when printing gold ink or silver ink. Red dry oil should generally be used instead of dry oil. Because white dry oil is combined with gold ink and silver ink. There is a tendency to make the original ink darker. This will affect the gloss of gold and silver inks.