Synthesis And Characterization Of Water-based Unsaturated Polyester Based On Itaconic Acid

The content of VOC in traditional solvent-based coating is so high that the safety of environment and health of people is damaged seriously during the procedure of producing and using this type of coating. The environment-friendly water-based waterborne alkyd resin has excellent overall properties and broad spaces of application and research as the major film-forming materials of water-based coating. The hydrophilic group is introduced into waterborne alkyd resin by hydrophilic monomer which is indispensablebringingthe water-solubility for waterborne alkyd resin. The commonhydrophilic monomer is toxic to certain extent currently because of the existing of benzene ring. So it has practical implications that the waterborne alkyd resinis synthesized by ISNa based on biomass which is the ramification of itaconic acid(IA).New water-based polyester PBIINa is prepared using IA, ISNa and BD as main raw materials by esterification-polycondensation process in the study. The influence on the performance of PBIINa is inspected, what is brought bymolar ratio of IA and ISNa, the type and dosage of catalyst, the chemical reaction time, and the chemical reaction temperature. The structure andproperties of the production are characterized by gel permeation chromatography(GPC), Fourier transform infrared spectrometer(FR-IR) and H nuclear magnetic resonance(1H-NMR), and also, the dissolving property of PBIINa in the water is tested. The study result shows that PBIINa appears the best perform mance except better solubility in water, which is produced on condition that the esterification temperature is 180℃, the ratio of n BD to n(IA+ISNa) is 1.05, the ratio of n ISNa to n IA is 0.2, the catalyzer is Sn Cl2, the dosage of catalyzer is 0.18 percent of IA, the esterification time is 5 hours, then the condensation polymerization pressure is-0.1Mpa, the polymerization temperature is 160℃, the polymerization time is 2.5h. The product is expected PBIINa according to the result of FT-IR and 1H-NMR.The PBIINa in aqueous dispersion is solidified into membranein separate methods using traditional heating method and microwave irradiation method, and then, a discussion about better conditions for performance of coating film is carried out according to some parameters of coating filmare detected such as the thickness, hardness, adhesive force, Water-resistant, angle of contact, and so on. The test of properties shows that coating film gets the best performance that the thickness of coating film is 21.8μm, the hardness reach to 5H, the grade of adhesive force is 1, and the water resistance could reach to 6 hours, on the condition that the concentration of dispersed system is 20%, the curing temperature is 70℃, the curing time is 4 hour, thedosage of curing agent is 0.3 percent of PBIINa, and the ratio of ammonium persulfate to sodium hydrogen sulfite is 1. The results indicated that microwave irradiation has great advantage that the reaction time is much shorter compared with traditional heating method.The microwave irradiation reduces the reaction time to 20 min that onlyoccupy 1/12 of the time of traditional heating method that improves the efficiency of curing greatly.At last, the absorption peak of PBIINa before and after solidified membrane is detected by FT-IR and thermal degradation of coating film is analyzed by thermo gravimetric analyzer(TGA). The FT-IR expresses that crosslinking and curing reactionhappens to thechemical bond of-C=C- in the molecule of PBIINa and the coating film is solidifiedcompletely. The analysis of TGA expresses that the coating film begins to decompose at 219.6°C and the rate of decomposition is-12.37%/min. The rate of decomposition reaches the maximum-32.61%/min at 389.3°C that the thermal degradation of coating film is good.