Titanium-nitride catalyzed polyester
View Patent ↗A method for making polyethylene terephthalate resin in which a titanium-nitride polycondensation catalyst is introduced during the initial stages of esterification or transesterification. The titanium-nitride polycondensation catalyst may be added to a mixture containing a terephthalate component and a diol component during the formation of a polyethylene terephthalate precursor. Subsequent polycondensation of the polyethylene terephthalate precursor forms a polyethylene terephthalate polymer.
1. A method for making titanium-catalyzed polyethylene terephthalate resin, comprising:
mixing a terephthalate component and a diol component to form a polyethylene terephthalate reaction mixture;
reacting the terephthalate component and the diol component in the polyethylene terephthalate reaction mixture to form polyethylene terephthalate precursors;
adding a titanium-nitride polycondensation catalyst to the polyethylene terephthalate reaction mixture as a suspension in the diol component, wherein the titanium-nitride polycondensation catalyst is added to the reaction mixture when the polyethylene terephthalate precursors achieve an average degree of polymerization of between 3 and 6; and
polymerizing the polyethylene terephthalate precursors via melt phase polycondensation to form a polyester melt comprising polyethylene terephthalate polymers;
wherein the titanium-nitride polycondensation catalyst consists of a titanium-nitride catalyst and the titanium-nitride catalyst is the only catalyst present during the reacting and the polymerizing.
2. A method according to claim 1 , wherein the step of reacting the terephthalate component and the diol component comprises reacting in an esterification reaction (i) a diacid component comprising terephthalic acid and (ii) a diol component comprising ethylene glycol to form polyethylene terephthalate precursors.
3. A method according to claim 1 , wherein the step of reacting the terephthalate component and the diol component comprises reacting in a transesterification reaction (i) a diester component comprising dimethyl terephthalate and (ii) a diol component comprising ethylene glycol to form polyethylene terephthalate precursors.
4. A method according to claim 1 , wherein each step is performed as a continuous process.
5. A method according to claim 1 , wherein one or more steps are performed as a semi-continuous process.
6. A method according to claim 1 , wherein one or more steps are performed as a batch process.
7. A method according to claim 1 , further comprising forming the polyethylene terephthalate polymers into preforms, bottles, or other containers.