Patent ID: 6255445
Filing Date: 2001-07-03
Classification: C08G,C08J

Abstract:
A process for film-blowing a poly(lactone), comprising:(a) providing a poly(lactone) having non-linear polymer chains, said poly(lactone) being formed by reaction between a lactone monomer and an initiator system comprising at least one polyfunctional initiator having at least three active hydrogens, the amount of said initiator being such that the theoretical molecular weight, per active hydrogen, of the poly(lactone) polymer chains formed by reaction with said initiator is at least 25,000, having a melting temperature of greater than 45.degree. C., having a shear viscosity, when measured at some temperature in the range of from 35 to 45.degree. C. above the melting temperature of the poly(lactone), of at least 6 kPas at 0.1 s.sup.-1 shear rate and not greater than 3.5 kPas at 100 s.sup.-1 shear rate, and having a shear viscosity activation energy of greater than 40 kJ/mol;(b) extruding said poly(lactone) through an annular die to form a tube of molten polymer;(c) inflating said tube to produce a bubble; and(d) cooling the bubble or allowing the bubble to cool to solidify the polymer.