Abstract: The method for the production of a polyester with improved melting properties and crystallization properties comprises the steps of (a) production of a pre-polyester melt with an average molecular weight (Mn) of 2000 to 16000 g/mol, (b) solidifying and shaping the melt into pre-polyester particles, and (c) thermally treating the pre-polyester particles in a solid phase in the presence of a transesterification catalyst whereby a molecular weight increase (?Mn) of more than 2000 g/mol occurs. In addition, the prepolyester particles have a carboxyl end group content (XCOOH) of between 0.25 and 0.6 before step c and during the thermal treatment step c, the proportion of the esterification reaction (E) to the polycondensation reaction (E+T) is between 0.5 and 1.

Abstract: The method for the production of a polyester with improved melting properties and crystallisation properties comprises the steps of (a) production of a pre-polyester melt with an average molecular weight (Mn) of 2000 to 16000 g/mol, (b) solidifying and shaping the melt into pre-polyester particles, and (c) thermally treating the pre-polyester particles in a solid phase in the presence of a transesterification catalyst whereby a molecular weight increase (?Mn) of more than 2000 g/mol occurs. In addition, the prepolyester particles have a carboxyl end group content (XCOOH) of between 0.25 and 0.6 before step c and during the thermal treatment step c, the proportion of the esterification reaction (E) to the polycondensation reaction (E+T) is between 0.5 and 1.

Abstract: The invention relates to a partially crystalline polyethylene terephthalate having a degree of polymerization which is greater than 80, particularly greater than 100, produced from a diol component and a dicarboxylic acid component, wherein according to the invention the DSC melting point, when measured with a heating rate of 10° C./Min during the first passage and second passage, is less than the melting temperature (Tm) of a comparable standard polyethylene terephthalate which is dependent upon the comonomer content.

Abstract: The invention relates to a method for production of a partly-crystalline polycondensate, in particular, a polyester or a polyamide, whereby a polycondensate prepolymer is firstly produced, which is prepared and formed into granules, by means of a die-face granulating device, with an average diameter of less than 2 mm, said granules being cut at the outlet from the die plate. The degree of crystallisation and the molecular weight are then increased in a solid-phase polycondensation process. For granulation, the polycondensate prepolymer melt is pressed through a die plate with a number of die perforations, preferably arranged on at least one annular track. The cutting is achieved by means of a circulating knife with a liquid jet.

Abstract: The invention relates to a method for producing a polyester hollow body or its preform with a reduced acetaldehyde content from a drop-shaped, globular or spherical polyester granulate with a granulate diameter of less than 2 mm. Said method is characterised in that the molecular weight of the polyester in the production step of melt-phase polymerisation is set to an intrinsic viscosity (IV) value of 0.15 to 0.4 dl/g, the melt is transferred to a drop-shaped, globular or spherical mould by drop-processing and subsequently solidifies, the molecular weight of the polyester in the production step of solid-phase polycondensation is increased to an IV value of greater than 0.65 dl/g and the polyester material that has been treated in this manner is shaped by being introduced into shaping means, to form the hollow body or its preform. The shaping process can be carried out by injection moulding, sintering or extrusion blow moulding.

Abstract: In a procedure for continuously crystallizing and polymerizing polyester and polyamide materials, amorphous material is first precrystallized, preferably in a fluidized bed (1,2), then heated up to the reaction temperature in a preheating zone (4) and finally polymerized and largely liberated from byproducts in a reactor (3). In this procedure, material from the discharge area of the preheating zone (4), of the reactor (3) or of a cooler (8) is subjected to an optical analysis in an analyzing unit whereby the degree of polymerization of the material and/or the contents of byproducts can be determined. The result of the analysis as actual value is compared in an comparator unit with a predetermined nominal value obtained in at least one calibration procedure for forming at least one controlled value serving to form at least one control signal that can be supplied to at least one final control element.