The role and scope of application of varnish - Industry news - Zhangjiagang Free Trade Zone kworld Chemical Technology Co., Ltd.

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The role and scope of application of varnish

2022-07-26 13:37:00

Coating varnish on the printed matter can not only increase the value of the printed product, but also has good adhesion, high gloss, smoothness and good leveling. The surface of the printed matter is bright and bright, the pattern is clear, and the hand feel is smooth, and we can continuously enhance the light resistance of the ink and increase the heat and moisture resistance of the ink. The varnish produced by Panax notoginseng is colorless and odorless, which can protect the environment. Varnish is an indispensable part of the printing industry. It is used to cover the surface of various products, materials or primers to protect and increase the gloss and texture. And for a variety of external products that need to increase brightness, they have their own needs for varnishes with different degrees of influence.

Precautions for glazing oil

●The pH value of water-based paint is generally between 8 and 8.5, which is a weak alkaline liquid.

The viscosity of water-based paint changes with the temperature, becomes thinner when heated, and thickens when cooled;

●The coating thickness of water sample light oil shall not be less than 1 s:

●When printing varnish, the adjustment of the drying treatment device of the printing machine should keep the temperature obviously lower than 36 degrees;

If water-based paint is stored for a long time, delamination will occur, it is recommended to use it evenly before mixing;

●Inks with poor resistance such as pink and bluish have the risk of fading after being painted with water-based paints;

●Online system uses water-based varnish, it is recommended that we do not add water;

Varnish application control

Viscosity Control

The viscosity of the varnish should be checked frequently in the application. The best viscosity range for offset printing is between 35 seconds and 60 seconds. Lower viscosity will cause oil rejection or varnishing rubber pile ink; higher viscosity will affect the normal management of the oil pump. work, causing oil break, rough leveling and drying technical problems.

avoid cracking

The application of varnish should be printed with ink with higher concentration and faster drying speed. At the same time, pay attention to the thickness of ink coating and the reduction of ink coating thickness to avoid cracking caused by thick ink layer, thin ink layer or slow drying speed of ink.

avoid pinholes

The oil suction pipe of the oil pumping system should be placed at the bottom of the oil drum, and the oil return pipe should be placed on the surface of the oil drum and against the wall of the oil drum, so that the recovered oil flows down slowly, so as to avoid the impact of the oil producing a large amount of oil in the oil drum. Micro air bubbles, causing pinhole or filming problems.

prevent sticking

After the film is dried, the varnished product will soften and stick back at higher temperatures and humidity, resulting in reduced print adhesion. Therefore, in printing, the temperature of the conveying stack should be controlled below 36 degrees as much as possible. In the case of high temperature or high humidity, especially in the summer rainy season, the storage and transportation of oil-based mimeograph products must pay attention to the control of temperature and humidity.

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