The Synthesis,Characterization And Catalytic Properties Studying Of Titanocene Dichloride Complexes

Polybutylene terephthalate(PBT for short),is one of the toughest engineering plastics.It is widely used in the fields of electronics,automobile parts,mechanical equipment,household wares,and so on.The aim of this study if to find a catalyst with high stability and high catalytic performance.We carried out the research that PBT is synthesized by titanocene complex as a catalyst.The main research contents are as follows:1)18 kinds of titanocene complexes are synthesized by aqueous phase method and interfacial method,with titanocece dichloride as a substrate and dicarboxylic acids(such as o-,m-,p-phthalic acid,and so on),salicylic acids(such as o-,m-,p-hydroxybenzoic acid,and so on),binary phenolic hydroxyl groups(such as o-,m-,p-benzenediol)as ligands.The structure of these complexes are analyzed by capillary melting point,IR spectrum,and ~1H NMR;2)Using singly these titanocene complexes as catalysts to synthesize PBT,under the same reaction conditions:n(PTA):n(BDO)=1:2,the dosage of catalyst is 400 ppm,esterification temperature is 210?,esterification temperature is 3 h,condensation temperature is 250?,condensation temperature is 60 min.Compared with TBT,We have screened out two kinds of catalysts with excellent catalytic performance,namely isophthalic acid-titanocene and terephthalic acid-titanocene.3)We investigate the appropriate reaction conditions for the synthesis of PBT catalyzed by isophthalic acid-titanocene and terephthalic acid-titanocene by orthogonal experiments.The result shows that under the conditions of using isophthalic acid-titanocene as a catalyst and n(PTA):n(BDO)=1:2,the appropriate reaction conditions is that he dosage of catalyst is 300 ppm,esterification temperature is 215?,esterification temperature is 3 h,condensation temperature is 250?,condensation temperature is 60 min;the intrinsic viscosity of PBT is 0.927 d L/g,the content of terminal carboxyl group is 25.7 mol/t,the melting range is 228?230?,the whiteness is 76.6,the percentage of THF in the distillate is 23.2%.Under the conditions of using isophthalic acid-titanocene as a catalyst and n(PTA):n(BDO)=1:2,the appropriate reaction conditions is that the dosage of catalyst is 400 ppm,esterification temperature is 215?,esterification temperature is 3 h,condensation temperature is 250?,condensation temperature is 60 min;the intrinsic viscosity of PBT is 0.945d L/g,the content of terminal carboxyl group is 20.1 mol/t,the melting range is 234?236?,the whiteness is 78.7,the percentage of THF in the distillate is20.5%.By contrast,we conclude that the most suitable catalyst to synthesize PBT is terephthalic acid-titanocene.4)The optimal reaction conditions for the synthesis of PBT which was catalyzed by terephthalic acid-titanocene was investigated by single factor experiments.The result is that n(PTA):n(BDO)=1:2,the dosage of catalyst is 400 ppm,esterification temperature is 220?,esterification temperature is 3.5 h,condensation temperature is250?,condensation temperature is 60 min;the intrinsic viscosity of PBT is 0.952d L/g,the content of terminal carboxyl group is 19.6 mol/t,the melting range is 236?238?.Compared with the standard of PBT base resin,the synthesis of PBT of catalyzed by erephthalic acid-titanocene is in accordance with the requirements.