An aromatic polyester having a repeating unit represented by formula (1) shown below and a terminal structural unit represented by formula (1e) shown below, wherein the proportion of the terminal structural unit per unit mass of the aromatic polyester is not more than 50 μmol/g.

—O—Ar.sup.1—CO—  (1)

—O—Ar.sup.1—CO—OH  (1e)

(In the formulas, Ar.sup.1 represents a 1,4-phenylene group, a 2,6-naphthylene group or a 4,4′-biphenylylene group. The hydrogen atoms that exist in the groups represented by Ar.sup.1 may each be independently substituted with a halogen atom, an alkyl group or an aryl group.)

A solid-state polymerized poly(tetramethylene-2,5-furandicarboxylate) polymer is produced in a process including: providing a poly (tetramethylene-2,5-furandicarboxylate) polycondensate having a number average molecular weight (Mn) of at least 10,000, as determined by Gel Permeation Chromatography (GPC) using polystyrene as standard, and having a content of carboxylic acid end groups of at most 50 meq/kg; and keeping the poly(tetramethylene-2,5-furandicarboxylate) polycondensate at a temperature in the range of 80 to 140° C. to obtain a semi-crystalline polycondensate; and subjecting the semi-crystalline polycondensate to solid-state polymerization by keeping the semi-crystalline polycondensate at a temperature of at least 140° C. and below its melting point, whilst the semi-crystalline polycondensate is either under a flow of inert gas or under vacuum to obtain the solid-state polymerized poly(tetramethylene-2,5-furandicarboxylate) polymer.

A solid-state polymerized poly(tetramethylene-2,5-furandicarboxylate) polymer is produced in a process including: providing a poly (tetramethylene-2,5-furandicarboxylate) polycondensate having a number average molecular weight (Mn) of at least 10,000, as determined by Gel Permeation Chromatography (GPC) using polystyrene as standard, and having a content of carboxylic acid end groups of at most 50 meq/kg; and keeping the poly(tetramethylene-2,5-furandicarboxylate) polycondensate at a temperature in the range of 80 to 140° C. to obtain a semi-crystalline polycondensate; and subjecting the semi-crystalline polycondensate to solid-state polymerization by keeping the semi-crystalline polycondensate at a temperature of at least 140° C. and below its melting point, whilst the semi-crystalline polycondensate is either under a flow of inert gas or under vacuum to obtain the solid-state polymerized poly(tetramethylene-2,5-furandicarboxylate) polymer.

The invention relates to a method for preparing a polyester of the poly(1,4:3,6-dianhydrohexitol-cocyclohexylene terephthalate) type using at least one nucleating agent. The invention also relates to a composition comprising a polyester of the poly(1,4:3,6-dianhydrohexitol-cocyclohexylene terephthalate) type and at least one nucleating agent as well as to a finished or semi-finished plastic article comprising the composition according to the invention.

The invention relates to the field of polymers and relates to a process for crystallizing polyester. More particularly, this is a crystallization process comprising a step of provision of a polyester comprising at least one 1,4:3,6-dianhydrohexitol unit, a step of provision of a coalescence-preventing additive, and a step of crystallization of said semicrystalline polyester. The process according to the invention makes it possible to greatly limit, indeed even to eliminate, the phenomenon of agglomeration of the polyester granules during the crystallization.

The invention relates to the field of polymers and relates to a process for crystallizing polyester. More particularly, this is a crystallization process comprising a step of provision of a polyester comprising at least one 1,4:3,6-dianhydrohexitol unit, a step of provision of a coalescence-preventing additive, and a step of crystallization of said semicrystalline polyester. The process according to the invention makes it possible to greatly limit, indeed even to eliminate, the phenomenon of agglomeration of the polyester granules during the crystallization.

The present invention relates to a polyester container. The polyester container is formed from a polyester resin containing a particular content of diol moieties derived from isosorbide and diethylene glycol, and thus can show high transparency in spite of a great wall thickness thereof.

The present invention relates to a polyester container. The polyester container is formed from a polyester resin containing a particular content of diol moieties derived from isosorbide and diethylene glycol, and thus can show high transparency in spite of a great wall thickness thereof.

The invention provides a resin composition that is capable of relaxing anisotropy while keeping the crystalline structure derived from liquid crystallinity and that has isotropic structure and physicality from a macroscopic view, even after the melt-processed molded article obtained by applying shear has been molded, cooled and fused without applying shear stress and subsequently re-cooled. The resin composition comprises a liquid crystal polyester resin (A) comprising structural unit (I) derived from a hydroxycarboxylic acid, structural unit (II) derived from a diol compound, and structural unit (III) derived from a dicarboxylic acid, and a resin (B) other than the liquid crystal polyester resin (A), and has an X-ray diffraction measured after fusing the resin composition that satisfies a specific condition.

The invention provides a resin composition that is capable of relaxing anisotropy while keeping the crystalline structure derived from liquid crystallinity and that has isotropic structure and physicality from a macroscopic view, even after the melt-processed molded article obtained by applying shear has been molded, cooled and fused without applying shear stress and subsequently re-cooled. The resin composition comprises a liquid crystal polyester resin (A) comprising structural unit (I) derived from a hydroxycarboxylic acid, structural unit (II) derived from a diol compound, and structural unit (III) derived from a dicarboxylic acid, and a resin (B) other than the liquid crystal polyester resin (A), and has an X-ray diffraction measured after fusing the resin composition that satisfies a specific condition.