The invention relates a novel polyglycolic acid. The polyglycolic acid comprises branched repeating units and linear repeating units. The polyglycolic acid may be produced from methyl glycolate by polycondensation in the presence of structure regulators, and exhibit excellent melt strength and thermal stability while maintaining good flowability and suitability for use in melt blow molding.

The invention relates a novel polyglycolic acid. The polyglycolic acid comprises branched repeating units and linear repeating units. The polyglycolic acid may be produced from methyl glycolate by polycondensation in the presence of structure regulators, and exhibit excellent melt strength and thermal stability while maintaining good flowability and suitability for use in melt blow molding.

The present application discloses a method for preparing polyester polyol comprising performing transesterification of raw materials containing inorganic oxyacid ester and polyhydric alcohol to obtain the polyester polyol. The polyester polyol obtained by the method described in the present application has higher heat resistance.

The present application discloses a method for preparing polyester polyol comprising performing transesterification of raw materials containing inorganic oxyacid ester and polyhydric alcohol to obtain the polyester polyol. The polyester polyol obtained by the method described in the present application has higher heat resistance.

The present invention relates to a kind of organic metal-free catalysts containing both electrophilic and nucleophilic dual-functions, preparation methods of making the same, and uses thereof. The organic metal-free catalysts in the present invention have the chemical structure shown in formula (I): ##STR00001##
Compared with the metal-free organic polymerization catalytic systems that have been reported before, the organic metal-free catalysts in this invention have the combined advantages of simple preparation, high reactivity, easy operation, low cost, wide applicability, easy for industrial production.

A catalyst/initiator system for polymerizing β-butyrolactone is described that includes a rare earth metal, a chiral ligand, at least one nucleophilic ligand, optionally at least one solvent ligand, and optionally an alkali based co-catalyst.

A catalyst/initiator system for polymerizing β-butyrolactone is described that includes a rare earth metal, a chiral ligand, at least one nucleophilic ligand, optionally at least one solvent ligand, and optionally an alkali based co-catalyst.

Provided is a process for producing a product having polyglycolic acid and glycolide from methyl glycolate. The process comprises esterification, polycondensation and optimization. Also provided are a product produced by the process and a method of changing the amount of the polyglycolic acid in the product by modifying the amount of an esterification catalyst and/or adjusting the reaction temperature.

The present invention provides a polyester resin and a hollow molded body containing reduced amounts of cyclic trimer and aluminum-based foreign matter, with maintained catalytic activity and a reduced catalyst cost. A polyester resin, comprising an aluminum compound and a phosphorus compound, and satisfying the following (1) to (3): (1) a content of aluminum element in the polyester resin is 9 to 19 ppm by mass, (2) a content of phosphorus element in the polyester resin is 22 to 40 ppm by mass. and (3) a mole ratio of phosphorus element to aluminum element in the polyester resin is 1.55 or more and 1.85 or less.

The present invention provides a polyester resin and a hollow molded body containing reduced amounts of cyclic trimer and aluminum-based foreign matter, with maintained catalytic activity and a reduced catalyst cost. A polyester resin, comprising an aluminum compound and a phosphorus compound, and satisfying the following (1) to (3): (1) a content of aluminum element in the polyester resin is 9 to 19 ppm by mass, (2) a content of phosphorus element in the polyester resin is 22 to 40 ppm by mass. and (3) a mole ratio of phosphorus element to aluminum element in the polyester resin is 1.55 or more and 1.85 or less.