| Abstract:Waterborne polyurethane (WPU) as a new surface sizing agent has been developed in recent years. WPU surface sizing agent was prepared by a pre-polymerization process. The waterproof property, surface property and mechanical properties of the paper sized by WPU with different NCO/OH molar ratio, different DMPA contents and different molecular structure were systematically examined. The results showed that water resistance of the papers sized with the WPU surface sizing agent dramatically increases. For example, Cobb value only 25.8% of the papers without surface sizing, surface gloss is 10 times to the unsized papers, at the same time, smoothness of the papers sized with WPU surface sizing agent can be 7 times high as the unsized papers. The folding endurance and tensile strength also increase obviously. WPU is a kind of surface sizing agent with wide application prospects. |
