Patent ID: 11859046
Assignee: ROQUETTE FRERES
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A process for producing a polyester comprising:
1,4:3,6-dianhydrohexitol units (A);
alicyclic diol units (B) other than the 1,4:3,6-dianhydrohexitol units (A); and
terephthalic acid units (C),
the polyester not containing any aliphatic non-cyclic diol units or comprising less than 5 molar % of aliphatic non-cyclic diol units, relative to all the monomer units of the polyester, and the polyester having a reduced viscosity in solution (25° C.; phenol (50% m): ortho-dichlorobenzene (50% m); 5 g polyester/1) of greater than 50 ml/g, the process comprising:
introducing, into a reactor, monomers comprising the 1,4: 3,6-dianhydrohexitol (A), the alicyclic diol (B) other than the 1,4:3,6-dianhydrohexitols (A) and the terephthalic acid (C), a molar ratio ((A)+(B))/(C) ranging from 1.05 to 1.5, the monomers not containing any aliphatic non-cyclic diols or comprising, relative to all of the monomers introduced, a molar amount of aliphatic non-cyclic diol units of less than 5%;
introducing a catalyst system into the reactor, the catalyst system comprising tin;
after introducing the catalyst system, polymerizing the monomers in the presence of the catalyst system to form a polyester, the polymerizing comprising:
a first stage of oligomerization carried out at a pressure of between 5 to 7.5 bar, during which a reaction medium is stirred under an inert atmosphere at a temperature in a range of 265 to 280° C.;
a second stage of condensation of the oligomers, during which the oligomers formed are stirred under vacuum, at a temperature in a range of 278 to 300° C. so as to form the polyester; and
recovering the polyester.