Study On The Synthesis And Application Of Environment-friendly Polyester Plasticizers

Plasticizer is the largest dosage of plastic additives, which safety is directly related to the health of human beings. In this study, under the guide of green chemistry, a series of excellent and environment-friendly polyester plasticizers were synthesized, and applied in substituting for phthalate plasticizers which are disputed increasing currently as PVC plasticizers.The adipate polyester plasticizers (poly diglycol adipate and poly triglycol adipate), maleate polyester plasticizers (poly diglycol maleate and poly triglycol maleate) and hexahydro-4-methylphthalate polyester plasticizers (poly diglycol hexahydro-4- methylphthalate and poly triglycol hexahydro-4-methylphthalate) were synthesized by adipate, maleate, hexahydro-4-methylphthalate, diglycol and triglycol via esterification reaction respectively, with tetra-n-butyl titanate as catalyst and 2-ethyl-hexanol as chain termination reagent. The optimized reaction conditions were determined after the investigation for the reaction temperature, the reaction time, the stuff ration, the amount of chain-end reagent and the amount of catalyst.The results show that the optimized synthesis conditions of adipate polyester plasticizers are as follows: n(adipic acid):n(dihydric alcohol)=1.0:1.2, n(2-ethyl-hexanol):n(adipic acid)=0.08:1.0, m(catalyst)=0.5%m(adipic acid and dihydric alcohol), reaction time 4 h in 200℃under normal pressure and 3 h in 210℃under a pressure of -0.090 MPa. The optimized synthesis conditions of maleate polyester plasticizers are as follows: reaction temperature 200℃, time 6 h, the molar ratio of dihydric alcohol and maleic anhydride is 1.70:1.0, the molar ratio of 2-ethyl-hexanol and maleic anhydride is 0.60:1.0, amount of catalyst 0.8% (based on the mass of maleic anhydride). The optimized synthesis conditions of hexahydro-4- methylphthalate polyester plasticizers are as follows: reaction temperature 220℃, time 5 h, n(hexahydro-4-methylphthalate):n(dihydri calcohol)=1.0:1.25, n(2-ethyl-hexanol): n(hexahy- dro-4-methylphthalate)=0.80:1.0, m(catalyst)=1.0%m(hexahydro-4-methylphthalate).The main properties of every polyester plasticizer were determined by physical and chemical methods, including the acid value, the density, the viscosity, saponification value, the molecular weight and the heating loss. Products were characterized by infrared spectrum and nuclear magnetic resonance, which proved the existence of characteristic absorption peaks of polyesters. TGA showed products were with good thermostabilityUsing tetrahydrophthalic anhydride(THPA), diglycol(DEG), 2-ethyl-hexanol, hydrogen peroxide as raw material, tetra-n-butyl titanate and formic acid as catalyst, epoxy poly(diglycol tetrahydrophthalic anhydride)(EPTA-2) was prepared via esterification and epoxidation reaction. The influences of esterification and epoxidation reaction conditions, such as reaction time, reaction temperature, stuff ratio, amount of used chain-ending reagent, catalyst dosage and the amount of H2O2 and formic acid were investigated. The results show that the optimized reaction conditions of esterification are as follows: the molar ratio of THPA, DEG and 2-ethyl-hexanol is 1.0:1.25:0.50, amount of catalyst 0.8% (based on the mass of THPA), reaction temperature 200℃and time 6 h. The optimum conditions of epoxidation are as follows: the mass ratio of PTA-2, formic acid and H2O2 is 1.0:0.50:0.90, reaction temperature 50℃, and time 1 h. Infrared spectrum, nuclear magnetic resonance and thermo gravimetric analyzer were adopted to characterize the structure and the thermostability of EPTA-2 systematically. The influence of EPTA-2 on the thermostability of PVC was investigated after the addition of EPTA-2 and DOP respectively. Comparing with DOP, after the addition of 50 phr (based on 100 phr PVC resin) EPTA-2, the 5% and 50% weight loss temperature of modified PVC was increased from 250.3℃to 273.7℃and from 312.3℃to 348.7℃respectively.The application performance of polyester plasticizers, including the compatibility with PVC, heating loss, migration loss and extraction loss were tested and compared with single size plasticizers such as DOP. The synthesized polyester plasticizers exhibit good withstand volatilization properties, withstand migration properties and withstand extraction properties.