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AssigneeReiter Automatic GmbH
InventorsAndre Matthaei, Peter Locker, Anreas Ecker, Ralf Muller
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The invention relates to a process and an apparatus for forming molten drops of precursors of thermoplastic polyesters or copolyesters as molten monomer, oligomer, monomer/glycol mixture or after partial polycondensator [sic] and melting to give a molten precursor, in which the precursor formed into drops is introduced into a gaseous medium, and the gaseous medium, after entry of the precursor formed into drops into the gaseous medium, accelerates the crystallization process by holding the drop-form precursor at a temperature above 100° C. and below its melting point for a limited time until crystallization of the drop at the surface of the precursor is complete. To this end, the apparatus has a fall tower, through which the gaseous medium flows in countercurrent from bottom to top, while the drops fall in the vertical direction from top to bottom into a collecting funnel with a precrystallized surface.
Process for forming drops of precursors of thermoplastic polyesters or copolyesters as molten monomer, oligomer, monomer/glycol mixture or after partial polycondensation and melting to give a molten precursor, in which the precursor formed into drops is introduced into a gaseous medium, characterized in that the gaseous medium, after entry of the precursor formed into drops into the gaseous medium, accelerates the crystallization process of the precursor and brings about the crystallization state of the precursor in an accelerated manner by holding the drop-form precursor at a temperature above 100° C. and below its melting point for a limited time until crystallization of the drop at the surface of the precursor is complete.
Process according to one of the preceding claims, characterized in that the gaseous medium is passed in countercurrent to a fall zone of the precursor formed into drops.
Process according to one of the preceding claims, characterized in that the precursor in molten form is formed into drops by vibration excitation.
Process according to one of the preceding claims, characterized in that the precursor having an intrinsic viscosity in the range from 0.05 to 0.3 dl/g is formed into drops.
Process according to one of the preceding claims, characterized in that the precursor is formed into drops having a diameter of from 0.3 to 3 mm.
Process according to one of the preceding claims, characterized in that the precursor is formed into drops whose diameter is to the extent of greater than 80% by weight in the region of twice the nozzle diameter, and a diameter less than the nozzle diameter occurs to the extent of less than 3% by weight and a diameter greater than three times the nozzle diameter occurs to the extent of less than 10% by weight of the precursor formed into drops.
Process according to one of the preceding claims, characterized in that a dust-particle content of less than 1% by weight of the precursor formed into drops occurs during drop formation.
Process according to one of the preceding claims, characterized in that a low-viscosity precursor having an intrinsic viscosity of less than 0.15 is formed into drops in an environment with fine polyester particles, resulting in coating of the drops at the surface with polyester particles, which promotes crystallization and prevents the solidified drops from sticking together.
Dependencies are inferred from the claim text.