Abstract: The invention provides methods and systems for manufacturing low-acid polyalkylene terephthalate, for example, polybutylene terephthalate (PBT). The invention also provides methods and systems for preparing macrocyclic polyester oligomer (MPO) from low-acid polyalkylene terephthalate. Finally, the invention provides methods and systems for preparing MPO via reaction of a diol and a dialkyl ester in an organic solvent to form non-isolated, low-acid polyalkylene terephthalate which undergoes cyclization (depolymerization) to form MPO.

Abstract: The invention provides methods and systems for manufacturing low-acid polyalkylene terephthalate, for example, polybutylene terephthalate (PBT). The invention also provides methods and systems for preparing macrocyclic polyester oligomer (MPO) from low-acid polyalkylene terephthalate. Finally, the invention provides methods and systems for preparing MPO via reaction of a diol and a dialkyl ester in an organic solvent to form non-isolated, low-acid polyalkylene terephthalate which undergoes cyclization (depolymerization) to form MPO.

Abstract: The invention provides methods and systems for manufacturing low-acid polyalkylene terephthalate, for example, polybutylene terephthalate (PBT). The invention also provides methods and systems for preparing macrocyclic polyester oligomer (MPO) from low-acid polyalkylene terephthalate. Finally, the invention provides methods and systems for preparing MPO via reaction of a diol and a dialkyl ester in an organic solvent to form non-isolated, low-acid polyalkylene terephthalate which undergoes cyclization (depolymerization) to form MPO.

Abstract: The invention relates to methods and systems for the use of an oligomer recyclate from a depolymerization product stream. The oligomer byproduct of a polyester depolymerization reaction can be used as a reactant in the formation of a polyester. For example, linear oligomer byproduct can be used as a reactant in a solution polymerization to form a low-acid polyalkylene terephthalate.

Abstract: The invention relates to methods and systems for selective removal of catalyst residue from a depolymerization product stream without a water quench, as well as methods and systems for subsequent recovery of residual linear oligomer. The substantially metal-free and substantially water-free residual oligomer byproduct can then be advantageously used as recyclate in a process for preparing MPO. For example, the residual oligomer recyclate can be used as a reactant in the polymerization and subsequent depolymerization (cyclization) of low-acid polyester to form MPO.

Abstract: Processes for isolating, formulating, and shaping macrocyclic oligoesters were developed which allow efficient production of macrocyclic oligoesters substantially free from solvent, which may include additives, fillers, and catalysts.

Abstract: Organo-titanate catalysts are prepared that are useful to catalyze depolymerization of a polyester to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.

Abstract: The invention relates to a method for producing low-acid polyalkylene terephthalate from which MPO can be advantageously manufactured. In certain embodiments, the acid content of commercially available polybutylene terephthalate (PBT) is reduced by adding a small amount of 1,4-butane diol (BDO) to a solution of the commercially available PBT in refluxing ortho-dichlorobenzene (oDCB) solvent.

Abstract: The invention relates to a method for producing low-acid polyalkylene terephthalate from which MPO can be advantageously manufactured. In certain embodiments, low-acid polybutylene terephthalate (PBT) is prepared by reacting low molecular weight, diol-stopped PBT pre-polymer with a linear oligomer recyclate in refluxing ortho-dichlorobenzene (oDCB) solvent. The linear oligomer recyclate may be a by-product of the depolymerization/cyclization of the low-acid PBT, thereby synergistically increasing overall conversion of reactants to the MPO product, cyclic polybutylene terephthalate (cPBT).

Abstract: In one aspect, the invention relates to processes for producing substantially free-flowing shapes of macrocyclic oligoester, wherein the freshly-shaped macrocyclic oligoester is maintained at elevated temperature for a sufficient time. In certain embodiments, the shapes are heated in water, thereby avoiding agglomeration during the heating process itself. In another aspect, the invention relates to processes for removing solvent from a solution of macrocyclic oligoester using elevated temperature, reduced pressure, or both, thereby obviating the need for an anti-solvent to precipitate the macrocyclic oligoester from the solution. Other aspects of the invention related to shaping of macrocyclic oligoesters are presented as well.

Abstract: The invention provides methods and formulations involving the use of promoters that accelerate the polymerization of macrocyclic polyester oligomers (MPOs). For example, in certain embodiments, the invention provides blends of macrocyclic polyester oligomer (MPO), catalyst, and promoter that are substantially stable at ambient temperature for a period of time. The blend material may be stored without premature polymerization of MPO or deactivation of catalyst. The invention also provides processes employing one-part, ready-to-polymerize blends that contain MPO, catalyst, and promoter, as well as processes in which the catalyst and promoter are used in separate streams and are contacted when it is desired to accelerate polymerization of MPO. Methods of the invention offer advantages in the manufacture of thermoplastic parts and composites, due at least in part to the unique properties of MPO.

Abstract: This invention relates to single-component and multi-component catalytic systems using aryl titanates. Aryl titanate compounds are useful as catalysts and co-catalysts in single-component and multi-component catalytic systems (e.g., for the polymerization of macrocyclic oligoesters and the depolymerization of polyesters). Multi-component catalytic systems using aryl titanates allow increased versatility in applications such as liquid molding.

Abstract: Processes for isolating, formulating, and shaping macrocyclic oligesters were developed which allow efficient production of macrocyclic oligoesters substantially free from solvent, which may include additives, fillers, and catalysts.

Abstract: Acid impurities, such as carboxylic acid-terminated polymers, are removed from macrocyclic oligoesters with ion exchange resins, resulting in macrocyclic oligoesters that are substantially free of acid impurities. The ion exchange resins can be regenerated anew and reused by washing the resins with various wash solutions. Macrocyclic oligoesters substantially free of acid impurities polymerize to much higher molecular weight polyesters than macrocyclic oligoesters containing acid impurities.

Abstract: This invention relates to single-component and multi-component catalytic systems using aryl titanates. Aryl titanate compounds are useful as catalysts and co-catalysts in single-component and multi-component catalytic systems (e.g., for the polymerization of macrocyclic oligoesters and the depolymerization of polyesters). Multi-component catalytic systems using aryl titanates allow increased versatility in applications such as liquid molding.

Abstract: Acid impurities, such as carboxylic acid-terminated polymers, are removed from macrocyclic oligoesters with ion exchange resins, resulting in macrocyclic oligoesters that are substantially free of acid impurities. The ion exchange resins can be regenerated anew and reused by washing the resins with various wash solutions. Macrocyclic oligoesters substantially free of acid impurities polymerize to much higher molecular weight polyesters than macrocyclic oligoesters containing acid impurities.

Abstract: Organo-titanate catalysts are prepared that are useful to catalyze depolymerization of a polyester to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.

Abstract: Physical properties, such as melting temperature of MPO compositions may be significantly modified by modifying the weight percentage of one or more of the constituent MPOs. For example, removal of a significant portion of the tetramer can afford low melting MPO compositions. In one aspect, the invention is related to a method for modifying a physical property of a MPO composition that includes the steps of (a) providing a composition that has at least two species of MPOs, and (b) changing the weight percentage of at least one species of the MPOs in the composition. In another aspect, the invention is related to a MPO composition that includes at least two species of MPOs where a species of the MPOs having the highest melting temperature is present in an amount less than or equal to 5%.

Abstract: This invention relates to single-component and multi-component catalytic systems using aryl titanates. Aryl titanate compounds are useful as catalysts and co-catalysts in single-component and multi-component catalytic systems (e.g., for the polymerization of macrocyclic oligoesters and the depolymerization of polyesters). Multi-component catalytic systems using aryl titanates allow increased versatility in applications such as liquid molding.

Abstract: Organo-titanate catalysts are prepared that are useful to catalyze depolymerization of a polyester to produce macrocyclic oligoesters substantially free from macrocyclic co-oligoesters.