Synthesis And Application Of Cationic Surface Sizing Agent

In recent years, the research of surface sizing agent has made great progress in China, and lead to lots of practical applications. However, as the research of surface sizing agent began very late in China, there are still many problems in the quality control of the products. The properties such as water resistance, stability and formability, are still not as good as the foreign products. Correspondingly, the product application is far behind. Therefore, it becomes necessary to develop the environmental-friendly polymer surface sizing agents with low price.We firstly synthesized the cationic surface sizing agent by emulsifier-free emulsion polymerization. The effects of the quantity, the type of the cation, the proportion and type of the soft-hard monomers on the sizability, the foamability and the stability were studied. The parameters such as the content and the type of the cation, the glass transition temperature of the product were confirmed(0.1%mass concentration, and the PCD content can be controled at the level of600ueq/L while the pH value is about4; the cation monomer with DMC as the intermediate; to control the Tg of the polymer at20-40℃by changing the soft-hard monomer proportion).By IR characterization, particle size measuring, particle charge test, the properties of CSE-80018was characterized and compared with the same type of foreign product. The results show that CSE-80018is a very good product with high cost performance.The sizing mechanism of two surface sizing methods (press sizing and film metering sizing) were introduced. The influence of the surface sizing method, the starch category, the pH value, the aluminum sulfate, the drying temperature, the electrical conductance and the aged time on the surface sizing effect of three kinds of surface sizing agent (AKD sizing agent, starch sizing agent and macromolecule sizing agent) were studied. The advantages and disadvantages of these surface sizing agents were also compared.The effect of aluminum sulfate on the performance of styrene-acrylic surface sizing agent, as well as the corresponding sizing mechanism, was also investigated. The result shows that aluminum sulfate can absorb and neutralize the trash separated out of the paper layer, and also lower the pH value of the system. As a result, the cation of the surface sizing agent was strengthened when the pH value is less than4. For the hydrated aluminum ion emerged from the system can form intermediate product with surface sizing agent, the cationic charge of the surface sizing agent were greatly increased. Therefore, it prefers to position on the surface of the paper, and reduces the penetration rate inside of the paper. As the function of the aluminum sulfate in the surface sizing agent system, the sizing effect of the styrene-acrylic surface sizing agent was greatly improved.