1. Field of the Invention
The present invention relates to the production of poly(ethylene-2,6-naphthalene dicarboxylates).
2. Discussion of the Background
Poly(ethylene-2,6-naphthalene dicarboxylates) are produced by the polyesterification of dimethyl-2,6-naphthalene dicarboxylate and ethylene glycol in the presence of polycondensation and polyesterification catalyst systems.
In the preparation of dimethyl-2,6-naphthalene dicarboxylate, significant amounts of methyl hydrogen 2,6-naphthalene dicarboxylate are also produced. Consequently, during a typical preparation of poly(ethylene-2,6-naphthalene dicarboxylate) from dimethyl-2,6-naphthalene dicarboxylate, the presence of methyl hydrogen 2,6-naphthalene dicarboxylate inhibits the polycondensation reaction. This inhibition produces a final product that has a lower than desirable inherent viscosity.
There is thus a need for producing a high quality poly(ethylene-2,6-naphthalene dicarboxylate) product from a dimethyl-2,6-naphthalene dicarboxylate starting material contaminated with methyl hydrogen 2,6-naphthalene dicarboxylate.