The invention relates to the synthesis method of polyglycolic acid (PGA) obtained by removing the excessive water and monomer formed subsequent to condensation by means of an organic solvent and using azeotropic distillation method in the presence of a catalyst. The invention is a synthesis method of polyglycolic acid with high molecular weight and high solubility, characterized by comprising the steps of placing the glycolic acid in reaction medium with a catalyst; using hydrophilic organic solvents for removing the excessive water and monomer formed during condensation; mixing and boiling the mixture; stabilizing the amount of solvent in reaction medium and distilling the water off by means of Dean stark apparatus and/or a similar apparatus; refluxing the solid polymer obtained at the end of the reaction with ethyl acetate and removing the same from monomer residue and catalyst.

A polylactic acid resin composition includes a polylactic acid resin in an amount of 99% by mass or more. A complex viscosity ?*.sub.(20) of the polylactic acid resin composition is 2?10.sup.3 Pa.Math.s or higher. A ratio of the complex viscosity ?*.sub.(20) to a complex viscosity ?*.sub.(5), which is represented by [?*.sub.(20)/?*.sub.(5)], is 0.6 or higher. The complex viscosity ?*.sub.(5) and the complex viscosity ?*.sub.(20) are complex viscosities respectively measured 5 minutes and 20 minutes after the start of measurement using a parallel plate-type rotary viscometer under measurement conditions below:

[Measurement Conditions] Parallel plates: 20 mm in diameter, made of aluminum; Temperature: 200? C.; Gap between the parallel plates: 1.00 mm; Frequency: 1 Hz (6.28 rad/s); Atmosphere: under dry air (dew point: ?60? C.); and Size of measurement sample: a strip that is 30 ?m thick, 7 mm wide, and 35 mm long.

A polylactic acid resin composition includes a polylactic acid resin in an amount of 99% by mass or more. A complex viscosity ?*.sub.(20) of the polylactic acid resin composition is 2?10.sup.3 Pa.Math.s or higher. A ratio of the complex viscosity ?*.sub.(20) to a complex viscosity ?*.sub.(5), which is represented by [?*.sub.(20)/?*.sub.(5)], is 0.6 or higher. The complex viscosity ?*.sub.(5) and the complex viscosity ?*.sub.(20) are complex viscosities respectively measured 5 minutes and 20 minutes after the start of measurement using a parallel plate-type rotary viscometer under measurement conditions below:

[Measurement Conditions] Parallel plates: 20 mm in diameter, made of aluminum; Temperature: 200? C.; Gap between the parallel plates: 1.00 mm; Frequency: 1 Hz (6.28 rad/s); Atmosphere: under dry air (dew point: ?60? C.); and Size of measurement sample: a strip that is 30 ?m thick, 7 mm wide, and 35 mm long.

Compositions of P4HB with high purity have been developed. The compositions are prepared by washing P4HB biomass prior to solvent extraction, and precipitating P4HB from solution. The same solvent is preferably used to wash the P4HB biomass, and as a non-solvent to precipitate the polymer from a P4HB solvent solution. The highly pure P4HB compositions are suitable for preparing implants. The implants may be used for the repair of soft and hard tissues.

Compositions of P4HB with high purity have been developed. The compositions are prepared by washing P4HB biomass prior to solvent extraction, and precipitating P4HB from solution. The same solvent is preferably used to wash the P4HB biomass, and as a non-solvent to precipitate the polymer from a P4HB solvent solution. The highly pure P4HB compositions are suitable for preparing implants. The implants may be used for the repair of soft and hard tissues.

A method for purifying polybutylene terephthalate (PBT) includes: providing or receiving initial PBT, in which oligomers and tetrahydrofuran are present; dissolving the initial PBT in hexafluoroisopropanol (HFIP) to form a solution, in which the oligomers are also dissolved in the HFIP; and contacting the solution with compressed CO.sub.2 at a temperature and a pressure, thereby precipitating the purified PBT, resulting from a large portion of the oligomers are still dissolved in the HFIP, in the operation the temperature is in a range of 20 C. to 35 C., and the pressure is in a range of 900 psi to 1400 psi. A device for purifying PBT is also provided.

The present invention relates to a process for the manufacture of an epoxy-functional polyester. The process according to the invention comprises the steps of a) providing a polyester having functional groups selected from hydroxyl groups and carboxylic acid groups, or mixtures thereof, b) reacting the functional groups of the polyester with an epihaloalkane to obtain an epoxy-functional polyester dissolved in a liquid phase, c) optionally adding an organic solvent to the liquid phase obtained in step b); d) precipitating the epoxy-functional polyester from the liquid phase obtained in step b) or in step c); and e) isolating the precipitated epoxy-functional polyester from the liquid phase by a solid-liquid separation technique. The thus obtained resin is in particular useful for use in powder coatings. The invention further relates to a solid epoxy-functional polyester obtainable by such process and to a coating composition, in particular a powder coating composition, comprising such solid epoxy-functional polyester.

The present invention relates to a process for the manufacture of an epoxy-functional polyester. The process according to the invention comprises the steps of a) providing a polyester having functional groups selected from hydroxyl groups and carboxylic acid groups, or mixtures thereof, b) reacting the functional groups of the polyester with an epihaloalkane to obtain an epoxy-functional polyester dissolved in a liquid phase, c) optionally adding an organic solvent to the liquid phase obtained in step b); d) precipitating the epoxy-functional polyester from the liquid phase obtained in step b) or in step c); and e) isolating the precipitated epoxy-functional polyester from the liquid phase by a solid-liquid separation technique. The thus obtained resin is in particular useful for use in powder coatings. The invention further relates to a solid epoxy-functional polyester obtainable by such process and to a coating composition, in particular a powder coating composition, comprising such solid epoxy-functional polyester.

The present invention relates to a method for preparing polylactic acid. According to the method for preparing polylactic acid, high quality polylactic acid can be provided by effectively removing residual monomers while minimizing property changes of the polylactic acid.

The present invention relates to a method for preparing polylactic acid. According to the method for preparing polylactic acid, high quality polylactic acid can be provided by effectively removing residual monomers while minimizing property changes of the polylactic acid.