Studt On The Synthesis And Film-forming Properties Of Itaconic Acid Unsaturated Polyester

Active unsaturated monomers are needed as diluents in the curing process of unsaturated polyester resin.The diluent can cross-link with polyester and reduce the viscosity of polyester.Styrene is the most commonly used diluent at present,but it has high volatility and is easy to cause serious environmental pollution problems.With the continuous improvement of people’s environmental protection concept,low styrene polyester and styrene-free polyester have become a research hotspot.In this paper,the bio-based materials itaconic acid,1,4-butanediol and adipic acid are copolymerized to reduce the dependence on petroleum-based chemicals.The replacement of styrene as a reactive diluent with dimethyl itaconate was applied to the coating and the film properties were analyzed to reduce the hydrocarbon volatilization during the curing process,achieving the goal of green environmental protection.Unsaturated polyester poly(butylene itaconate-co-butylene adipate)(PBIA)was synthesized by direct esterification polycondensation of itaconic acid(IA),adipic acid(SA)and 1,4-butanediol(BDO).The effects of reaction conditions on the properties of the product were investigated.The experimental data showed that under the protection of nitrogen,the esterification temperature was 165℃,the esterification time was 6 h,the polycondensation temperature was 180℃,the polycondensation time was 2 h,tetrabutyl titanate was used as catalyst,hydroquinone was used as polymerization inhibitor,alcohol-acid ratio was 1.2:1,at which time the acid value of the product was 10.49mgKOH·g~-11 and the molecular weight was 1675.On this basis,a series of copolyester PBIA with controllable properties were obtained by changing the molar ratio of saturated acid to unsaturated acid.The results show that when the ratio of adipic acid to itaconic acid is 8:2,PBIA has better performance and the dispersion coefficient is the narrowest.The structure of PBIA can be determined by FT-IR and ~1H-NMR spectra.Using dimethyl itaconate instead of styrene as active diluent,the self-made PBIA was mixed with initiator,promoter and diluent to form an unsaturated polyester coating system.The dosage of initiator,accelerant and diluent and the selection of accelerant were explored.The changes of dry time,gel rate,conversion rate and volatile matter were also investigated.The results showed that when the methyl itaconic acid two methyl ester was used as active diluent,the initiator peroxide content of cyclohexanone was 2.5%,the content of cobalt iso-octanate was 0.4%,the amount of diluent was 30%,the curing time was 5.5 h,the gelation rate reached 76%,the 20 minutes before curing was slightly volatilized,after 40 min,almost no volatilization,curing volatilization is 15%,which is5%lower than styrene;when curing is complete,the conversion rate is 50%,and the gelation rate is 76%.On the basis of this,the addition of calcium carbonate filler modified,the results show that:calcium carbonate filler can improve product performance,calcium carbonate content is 50%of the quality of polyester is appropriate,at this time the solidification volatiles are divided into 7.75%,water absorption is 17%,The volume shrinkage was 3.2%.Dimethyl itaconate and styrene were used to prepare unsaturated polyester coatings.The effects of diluent dosage,curing temperature and time,initiator dosage on film properties were investigated.The results show that under the same conditions,when the diluent dimethyl itaconate is 30%,the film achieves the best performance:hardness is 4H,adhesion is 1,impact strength is 50 cm.When styrene is used as diluent and the diluent content is 10%,the film achieves the best performance:hardness is 3H,adhesion is 1,impact strength is 50 cm.Therefore,it can be concluded that dimethyl itaconate as dilution can improve the curing efficiency and optimize the performance of the film,but its hydrophilicity is poor,so it has the disadvantages of higher curing temperature and more dosage.Through SEM morphology analysis and thermal performance analysis of the coating,it was concluded that dimethyl itaconate had better dilution effect,better thermal stability and heat resistance of the coating,and the addition of calcium carbonate filler could improve the thermal performance of the coating.