Patent ID: 6339109
Filing Date: 2002-01-15
Classification: B29C,C08J

Abstract:
A method of preparing cellular pellets suitable for use in solid state polymerization from a prepolymer comprising a blowing agent, the method comprising the steps of:a) extruding the prepolymer through a die, the die maintained at conditions such that the blowing agent remains in the condensed phase in the prepolymer prior to emerging from the die; b) upon emergence of the prepolymer through the die, substantially simultaneously cooling the prepolymer by contacting the prepolymer with a cooling agent and cutting the prepolymer; the conditions outside the die being maintained such that the blowing agent vaporizes in the prepolymer to form pores; and c) effecting contact of the cellular pellets with a crystallizing agent comprising at least 95% by weight of an alcohol.