In the sizing process of surface sizing agent, its sizing performance is affected by various environmental factors. For example, the pH, conductivity, and temperature of the system, as well as the sizing method and drying process of the paper machine, will all affect the sizing effect of the surface sizing agent. For example, when the temperature of the coating system is too high, it will cause serious hydrolysis of the AKD surface sizing agent, resulting in an increase in product consumption; when the content of impurity ions in the coating system is too high, it will easily lead to the flocculation of the polymer surface sizing agent When the drying temperature of the paper machine is not enough, the surface sizing agent cannot be spread completely on the paper surface, resulting in poor sizing effect or too long curing time. Therefore, only after fully understanding the sizing influencing factors of various types of surface sizing agents, can the application and debugging of surface sizing agents be better carried out in the actual production process.
As one of the commonly used sizing agents in the paperboard sizing process, the styrene-acrylic surface sizing agent often needs to be combined with aluminum sulfate for sizing during the sizing process, which helps to improve the sizing effect. The figure below is the trend graph of the influence of aluminum sulfate addition on the sizing performance of the styrene-acrylic surface sizing agent in the enzyme modified starch and ammonium persulfate (APS) modified starch system (surface sizing agent on the system The absolute dry addition amount is 0.1%)
The sizing performance of styrene-acrylic surface rubbers all become better with the increase of the amount of aluminum sulfate in the system (the smaller the Cobb value, the better the sizing performance or sizing effect), and when the amount of aluminum sulfate added in the system When it reaches 0.1%, the sizing performance of the product basically tends to be stable.
So why aluminum sulfate can improve the sizing effect of styrene-acrylic type surface glue? A series of experiments have confirmed that: during the surface sizing process, adding an appropriate amount of aluminum sulfate to the sizing system, in addition to adsorption and neutralization In addition to the anionic garbage such as organic or inorganic substances precipitated in the paper layer (obvious in the actual production process); it can also reduce the pH of the system, thereby enhancing the cationicity of the surface sizing agent; and when the pH is less than 4, a large amount of The hydrated aluminum ion and the surface sizing agent form an intermediate product, which greatly increases the cationic charge of the surface sizing agent molecule, making it more likely to be fixed on the surface of the paper sheet, and reducing the probability of penetrating into the paper sheet. It is precisely because of these effects of aluminum sulfate in the sizing system that it can significantly improve the sizing effect of styrene-acrylic surface sizing agents, and play a role in promoting sizing (under the same sizing effect) , Can greatly reduce the amount of surface sizing agent used). Therefore, it can also be called a surface sizing accelerator.
Post time: Dec-26-2021