Special waterborne polyurethane modified resin method
Time：2023-06-17
When the waterborne polyurethane resin improves a single performance or comprehensive performance of wood through modification to meet our application in different industries, the following three methods are generally used to achieve it;
1、 Internal crosslinking method;
In order to improve the physical properties and water resistance of the film, the aqueous polyurethane with appropriate crosslinking degree can be directly generated. Generally, the following methods can be selected; To complete:
1. Polyols and polyisocyanates with appropriate degree of polymerization (generally tri degree of polymerization) are introduced into the prepolymer. The common chemicals are TMP, HDI Trimer, IPDI trimer, etc.
2. Waterborne aliphatic polyurethane can select appropriate polyamines for chain extension, so that the generated biological macromolecules have micro chemical cross-linking structure. The common diversified amines are diethylenetriamine, triethylenetetramine, etc.
3. In addition, 1 and 2 modes are selected.
For the internal crosslinking modification of waterborne polyurethane, it is important to grasp the internal crosslinking degree. If the internal crosslinking degree is too low, the actual effect of modification is not significant. If it is too high, its film-forming characteristics will be damaged.
2、 Self crosslinking method;
In short, the self crosslinking method means that after the aqueous polyurethane film is formed, it can carry out chemical changes to complete chemical crosslinking, improve the chemical crosslinking degree of the film, and improve the characteristics of the film. Therefore, it is necessary to modify the macromolecular formula of water-soluble polyurethane. For example, it can be completed by introducing dry oil fatty acids (double bond structure) and their polyalkoxy silicon units, so as to promote the full-automatic air oxidation chemical cross-linking reaction and hydrolysis condensation reaction after film formation, and improve the comprehensive energy. This method has a wide range of applications, and there are existing related products on the market.
3、 Diplomatic Union Act;
The anionic waterborne polyurethane prepared by self emulsification method still has a lot of carboxyl groups after film forming, which makes the wear resistance of the film worse. Like oily polyurethane resin, waterborne polyurethane can be added with diplomatic coupling agent before construction. After film forming, it can reflect the reaction of functional groups with carboxyl groups and diplomatic coupling agents in the film. Removing the hydrophilic groups of the film can greatly improve the water resistance of the film. In addition, it can also improve the physical properties of the film. Common cross-linking agents include aziridine, carbodiimide, water dispersible polyisocyanate, epoxy resin, amino resin, epoxy siloxane, etc.
