What factors affect the drying speed of flexo water-based pre-printing ink?
Release Time : 2025-05-14
The drying speed of flexo water-based pre-printing ink is affected by many factors, and understanding these factors is crucial to controlling printing quality and production efficiency.
The composition and formulation of flexo water-based pre-printing ink are intrinsic factors that affect the drying speed. The drying speed will vary depending on the proportion and type of resin, pigment, solvent and additive in the water-based pre-printing ink. For example, the glass transition temperature of the resin is low, the molecular chain segments move more easily, and the ink usually dries faster. The hygroscopicity and specific surface area of the pigment will also affect the drying. Pigments with strong hygroscopicity or large specific surface area will absorb more water, thereby slowing down the drying speed of the ink.
The ambient temperature and humidity have a significant impact on the drying speed of flexo water-based pre-printing ink. As the temperature rises, the molecular movement intensifies, the water evaporation rate accelerates, and the ink drying speed also increases accordingly. Generally speaking, the drying speed can be increased by about 1-1.5 times for every 10°C increase in temperature. When the humidity increases, the water vapor content in the air increases, the driving force for water evaporation decreases, the water in the ink is difficult to volatilize, and the drying speed will slow down. For example, in an environment with 80% humidity, the ink drying time may be 2-3 times that in an environment with 40% humidity.
The printing speed is related to the ink drying speed. If the printing speed is too fast, the time left for the ink to dry after it is transferred to the substrate is relatively reduced, and the drying speed will appear insufficient, which may cause the ink to not dry completely and cause problems such as adhesion. On the contrary, when the printing speed is slow, the ink has more time to dry, but it is also necessary to avoid blocking of the plate due to excessive drying. Therefore, it is necessary to reasonably adjust the printing speed according to the drying characteristics of the ink and the performance of the printing equipment to achieve the best drying effect.
Different substrates have different effects on the ink drying speed. If the surface of the substrate is loose and porous, such as paper, it will absorb moisture from the ink and help the ink dry. In addition, the tightness and sizing of the paper will also affect the absorption effect. Paper with low tightness and low sizing has strong water absorption capacity and fast ink drying speed. For substrates with smooth surfaces, such as plastic films, they have poor ink absorption, and the ink drying mainly relies on the natural volatilization of water, and the drying speed is relatively slow. In addition, some substrates may react chemically with certain components in the ink, thus affecting the drying speed.
Good ventilation can promptly remove the water volatilized during the ink drying process, maintain the freshness and dryness of the air in the printing environment, create favorable conditions for water evaporation, and accelerate the drying speed of the ink. Poor ventilation will cause water vapor to accumulate in the printing environment, hinder the further volatilization of water in the ink, and prolong the drying time. In actual production, exhaust fans and air conditioning systems are usually installed to improve ventilation conditions to improve the drying efficiency of the ink.
The type and performance of the drying equipment directly determine the effect and speed of the flexo water-based pre-printing ink drying. Common drying equipment includes hot air drying, infrared drying, and ultraviolet drying. Hot air drying blows hot air on the surface of the ink to accelerate the evaporation of water; infrared drying uses the thermal effect of infrared rays to quickly heat up and evaporate the water in the ink; ultraviolet drying triggers photochemical reactions in the ink through ultraviolet irradiation, so that the ink is quickly solidified and dried. Different drying equipment has different drying principles and efficiencies. Appropriate drying equipment should be selected according to the characteristics of the ink and the requirements of the printing process, and the drying parameters, such as temperature, wind speed, irradiation time, etc., should be reasonably set to achieve the ideal drying speed.
The larger the coating amount of flexo water-based pre-printing ink, the longer it takes to dry. Because the larger the coating amount, the thicker the ink layer, the longer the path for the internal water to diffuse outward, and the greater the resistance to water evaporation. Moreover, a larger amount of ink requires more heat and time to completely dry it. During the printing process, the coating amount of the ink should be reasonably controlled according to the requirements of the printing pattern and the characteristics of the substrate, in order to ensure both the printing quality and the drying speed of the ink, and avoid poor drying due to excessive coating amount.