The Synthesis And Modification Of Waterborne Polyurethane Resin

In this dissertation, the experimental scheme of inner and outer crosslinking technologies were used to realize the structure modification of waterborne polyurethane resins which improved the properties of waterborne polyurethane resins, such as water-resistant and solvent-resistant etc. The dissertation consists of two parts as follows.The first part, waterborne polyurethane resin modified by trimethylolpropane dehydrated castor oleate (TMPDCO) was carried out. The synthesis technology of TMPDCO was studied. The optimized reaction time (8h) and reaction temperature (160℃) were determined by measuring esterification ratio of reaction system and observing the products color. The desired TMPDCO product with hydroxyl value of 257.2mgKOH·g-1 was synthesized. The effect of TMPDCO content on water-resistant chemical-resistant and heat-resistant of waterborne polyurethane films was researched. The results showed that when the mol content of TMPDCO was 40%, the films showed the best chemical-resistant and heat-resistant. While soaking in water for 6d at ambient temperature, the absorption rate was only 6.9%, and the films appearance has no change. The films has no change while soaking in boiling water for 15min, and showed good heat-resistant.The heat-resistant temperature was 85℃. The ambient curable mechanism was given. The effect of R on mechanical properties was researched. With increas of R, the films became brittle and mechanical properties improved. With decreas of R, the hardness of films decreased and elongation could be minished. When R was 5, the film showed the best properties. The crosslinking degree and Tg of PU film were increased with the addition of TMPDCO. The E-44 content influenced the appearance of emulsion, the absorption rate and low temperature flexibility of the films etc. The film showed the best properties when the E-44 content was 2.0%-4.0%.The second part, anionic waterborne polyurethane resin terminated by HEMA was prepared. The effect of TMPDCO content, carboxyl content, different polyols on water-resistant and mechanical properties of waterborne polyurethane films were researched. The effect of blocking agents on water-resistant and high temperature stability were studied. The effect of outer crosslinking on water-resistant of waterborne polyurethane films was researched. The result showed that the water-resistant of the films could be improved with the TMPDCO addition. When the mol content of TMPDCO was 40%, soaking in water for 6d at ambient temperature, the films absorption rate was only 7.1%, and film appearance has no change. In order to decrease the absorption rate, the carboxyl content should be the minimum to keep the dispersion stable. When the polyester as flexbile polyols, the PU resin compared with polyether-PU resin showed the better water-resistant ability. When HEMA used as blocking agent, the crosslinking degree and Tg of the PU film were enhanced, and the PU emulsions showed the better high temperature stability than the PU emulsions blocked by PETA. When PETA instead of HEMA as blocking agent, there was more double bond on the molecule chain, and the films showed the better water-resistant. The crosslinking degree and water-resistant of waterborne polyurethane films were increased or improved when the outer crosslinking ingredient i.e. ethyleneimine was added in the PU emulsions.