First, the impact of ambient temperature and humidity
1. Impact of ambient temperature
When the temperature rises, the movement speed of molecules is accelerated, the internal energy of molecules is increased, and it is easy to generate more peroxides with activated genes, thus accelerating the polymerization of oil molecules. Therefore, as the temperature rises, the oxidation polymerization reaction of the ink will increase, thus speeding up the drying of the ink.
The drying process of the ink film is an exothermic reaction, and the heat released during the drying of the printing sheet will also accelerate the drying speed of the imprint. The effect of temperature on the speed of imprinting drying is very obvious, the temperature of the environment increases, the ink dries faster, and the reverse is slow. For example, in the hot summer weather, light fast drying ink can be quickly dried without adding dry oil, but in the cold winter, you need to add dry oil.
2. The impact of ambient humidity
In the offset printing process, water is needed to moisten the printing plate, water is a polar molecule, oil is a non-polar molecule, because water wetting the printing plate, there will be ink emulsification phenomenon, the ink emulsification control in the range of 10~30%, the water polymerization and evaporation rate is closely related to the drying of the impression. Since water molecules are highly polar substances, the presence of water can prevent the oxidation and polymerization of oil molecules into films, which will affect the drying speed of imprinting, and the level of environmental humidity will play a certain role in the evaporation rate of water. With the increase of ambient humidity, the activity of oxygen in the air will also be weakened, reducing the oxygen absorption of the ink, and the emulsified water in the inner layer of the ink film will also soften the ink film, thus slowing down the drying speed of the ink. Therefore, in the offset printing process to control the balance of ink, under the premise of not dirty version, use as little water as possible, so as to reduce the emulsification of ink, ink water content, the drying of the impression is very close.
Second, the impact of ink auxiliary materials
Transparent diluent and white oil, adhesive, etc. have the property of inhibiting ink drying, so that the drying of imprinting slows down. Diluent, willy oil, white ink, white oil and other main components are binder and aluminum hydroxide often have the presence of aluminum oxide, it is insoluble in water. Because aluminum hydroxide is easy to dissociate in water, it will increase the degree of emulsification of the ink in printing, so the printing will dry slowly. Vili oil is generally used as a diluent for multi-color overprinting ink of ordinary products, and the color of the diluted ink is basically not affected, but the brightness is general and the drying is slow. White oil is a kind of white translucent emulsion, using it to dilute the ink can reduce the viscosity of the ink, uniform color matching, white oil has non-dry, quality pine contains water, so that the ink accelerated emulsification, water inhalation ink layer and then gradually evaporated out, blocking the oxidation polymerization process of ink, will seriously affect the drying speed of imprinting.
In the offset printing process, in order to change the printability of the ink, or reduce the viscosity of the ink, often add non-dry auxiliary materials such as tackifier, basically does not affect the gloss and fluidity of the ink color. However, it can not be used too much, because of its non-dry and permeable substances, easy to cause the drawbacks of slow drying of imprinting, and the content in the ink is less than 5%.
In general, if the ink needs to be diluted and removed, the amount of drier should be increased in the ink accordingly. Such as: red, white dry oil.
Third, the influence of water tank solution
The water tank solution is inseparable from acidic substances, such as phosphoric acid, citric acid, etc. First, the flat gravure needs to supplement the inorganic salt layer lost in the printing process, phosphoric acid and other acidic substances have the function of cleaning the ink, and the acidity will cause the drying of the ink to be destroyed. The more acidic the water tank solution, the slower the drying time of the ink, so it is necessary to control the PH value of the water tank solution, and operate according to the instructions of the wetting powder when deploying the water tank solution.
