Several methods of adjusting the humidity of the ink in the offset printing process

1. Replace the ink adjusting oil completely with a debonding agent

during production. When printing large-area field versions. Ink is not easy to be evenly distributed in the process of ink roller transfer, or "paper fluffing" or roughness of printed products occurs. Generally caused by the high viscosity of the ink.

The main component of the debonding 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 ink adjustment (we mainly use No. 6 oil) is dry. The main function of vegetable oil is to improve the fluidity of ink and reduce the viscosity of ink. Both the debonding agent and the adjusting ink can reduce the viscosity of the ink, but their properties are not exactly the same. The debonding agent has the effect of inhibiting the drying of the ink and reducing the adhesion of the ink layer to the paper while reducing the viscosity of the ink. Ink ink can reduce the viscosity of the ink and increase the fluidity of the ink in the ink. Although it can affect the drying speed of the ink layer, it is not obvious. If an excessive amount of debonding agent is added to the ink to reduce the viscosity of the ink, it will easily cause excessive emulsification of the ink, resulting in the phenomenon of dry or weak imprinting, flying ink, etc., which has a great impact on post-processing such as polishing and coating serious. Therefore, it is not necessary to use it as much as possible. If you need to use 6 # ink, you can replace it, and pay attention to the amount of addition, do not exceed 3%, and increase the amount of desiccant.

2. Use white ink as diluent

Individual color inks need to add a diluent to the original ink to make it a light-colored ink, this diluent should have colorless and transparent properties. Both the brightening paste and the velvet oil are ideal impulsive agents. It has the effect of not changing the hue of the original ink but changing the depth of the original ink. If white ink is used as a diluent. Is inappropriate. Because white ink has a white hue, it will change the hue of the original ink so that the original ink tends to white and tender jade ink instead of becoming a light ink. This is contrary to the original intention of the operator to need light-colored ink. And in the offset printing process. If there are too many white ink components in the ink, due to the large proportion of white ink pigment particles, pigment particles will pile up on the printing plate or blanket during the ink delivery process. And cause the defects of rough imprint.

3. Do not distinguish the different roles of anti-sticking agent and de-sticking agent

Adding anti-sticking agent to the ink can prevent or reduce the problem of sticking on the front and back of the printed paper. The detackifier is to reduce the viscosity of the ink, it mainly plays its role in the process of ink transfer during printing. If the two are confused without distinction, it is likely that other problems will arise.

If a detackifier is added to the ink in order to prevent the ink on the front and back of the paper from sticking, the "non-dry" nature of the detackifier will prolong the drying time of the ink layer of the printed matter, which in turn will make the surface of the paper more sticky and dirty.

on the other hand. If more anti-blocking agent is added in order to reduce the viscosity of the ink in the printing process, it will not only play a good role in reducing the viscosity. It will also "coarse" the ink. Make it tarnish and affect the quality of the product.

Fourth, do not pay attention to the difference between red explosive oil and white explosive oil

Although red dry oil (also known as drilling dry oil) and white dry oil (also known as dry oil) are both desiccants for inks, the composition of each of them is different. Make the drying form of the ink layer also different.

Adding red dry oil to the ink can greatly accelerate the speed of oxidative film formation on the surface of the ink layer, that is, quickly dry on the surface of the ink layer. But red dry oil can't promote the dry operation speed inside the ink layer to be greatly improved. White oil has the performance of promoting the overall drying of the ink layer. When white ink is added to the ink, the drying speed of the surface and inside of the ink layer can be greatly improved. therefore. When we use desiccant. Attention must be paid to the difference between the two dry forms. E.g. For the drying of the ink layer surface. Red dry oil is better than white dry oil.

However, in the case of a solid printing plate or paper with a thick printing ink layer, due to the relationship between acidity and alkalinity, the drying performance of the ink layer is not good. The surface is dry but the inside is not very dry. In the case of such a printed product, in the case of external friction, it is easy to wipe off the ink layer, leaving the printed product with scratches and affecting the quality of the product.

In addition, when printing gold ink and silver ink, it is necessary to add a desiccant. Generally, red dry oil should be used instead of white dry oil. Because the combination of white dry oil and gold ink and silver ink. It has a tendency to make the original ink color darker. In this way, the printed product will affect the gloss effect of gold and silver ink.