| abstract |
The present invention relates to a process for preparing transparent polybutylene naphthalate polyester, for improving barrier performance of polyesters used in making of monolayer or multilayer containers, comprising steps of: a) mixing butane diol with polymerization catalysts, monoethylene glycol, color toner, and at least one crystallization suppressing agent, wherein said crystallization suppressing agent controls the rate of crystallization so as to control size and shape of crystals to ensure transparency; b) reacting said mixture with naphthalene dicarboxylic acid or ester thereof to obtain oligomerized product via esterification or ester interchange; c) polymerizing said oligomer using at least one polymerization catalyst to obtain amorphous polybutylene naphthalate polyester chips; d) crystallizing said polybutylene naphthalate polyester chips; and e) subjecting said polyester chips to solid state polymerization to upgrade the intrinsic viscosity (I.V.) up to more than 0.40 dl/gm. |