Crystalline form of poly(ethylene 2,6-naphthalate) and a method for its production
AssigneeE. I. Du Pont de Nemours and Compant
InventorsJan M. Stouffer, Elwood Neal Blanchard, Kenneth Wayne Leffew
Life of this patent
Estimating the term…
Abstract
Disclosed herein is a novel crystalline form of low molecular weight poly(ethylene 2,6-naphthalate). This crystalline form may be produced from molten or glassy low molecular weight poly(ethylene 2,6-naphthalate) material by means of rapid heat transfer to or from the material. The poly(ethylene 2,6-naphthalate) composition is suitable for use as a starting material for solid-state polymerization in order to produce polymers of higher molecular weight.
Claims26
A composition, comprising poly(ethylene 2,6-naphthalate) having an average apparent crystallite size of 10.0 nm or more, determined from 110 reflection.
Particles of modified or unmodified poly(ethylene 2,6-naphthalate) having an average apparent crystallite size of 10.0 nm or more, determined from the 110 reflection.
A process for crystallizing poly(ethylene 2,6-naphthalate), comprising cooling at a rate sufficient to cool a molten poly(ethylene 2,6-naphthalate), or heating at a sufficient rate to heat a glassy poly(ethylene 2,6-naphthalate), to a temperature of about 130.degree. C. to about 250.degree. C., to produce a crystalline poly(ethylene 2,6-naphthalate) having an average apparent crystallite size of 10.0 nm or more, as determined from the 110 reflection, and having a degree of polymerization (DP) of at least about 4 and an inherent viscosity of less than about 0.4 dl.
A process for the solid-state polymerization of poly(ethylene 2,6-naphthalate), comprising heating particles of poly(ethylene 2,6-naphthalate), in an inert gas flow or vacuum, to above their T.sub.g but below their melting point, the improvement comprising starting with poly(ethylene 2,6-naphthalate) particles having an average apparent crystallite size of 10.0 nm or more, as determined from 110 reflection, a degree of polymerization (DP) of at least about 4 and an inherent viscosity of less than about 0.4 dl, wherein solid state polymerization proceeds until the poly(ethylene 2,6-naphthalate) reaches an inherent viscosity of 0.5 to 2.0 dl/g.
A process for the solid-state polymerization of poly(ethylene 2,6-naphthalate), comprising:
- (a) producing a prepolymer of PEN having a degree of polymerization of at least about 4 and an inherent viscosity of less than about 0.4 dl/g;
- (b) forming the prepolymer of step (a) into pellets having an average apparent crystallite size of 10.0 nm or more, as determined from 110 reflection;
- (c) heating particles of poly(ethylene 2,6-naphthalate) in an inert gas flow or vacuum to above their T.sub.g but below their melting point, to produce a polymer having an inherent viscosity (I.V.) of 0.5 to 2.0 dl.
Dependencies are inferred from the claim text.