Process for making thermoplastic polymer pellets
AssigneeExxonMobil Chemical Patents Inc.
InventorsAndy Haishung Tsou, Mohsen Shahmirzadie Yeganeh, Gregory K. Hall
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Abstract
Provided is a process for making thermoplastic polymer pellets. The process has the following steps: (a) melting a thermoplastic polymer to form a polymer melt; (b) extruding the melt through a die to form a substantially continuous molten polymer extrudate wherein the die has a contact surface bearing a polymer coating having a surface energy of less than 25 mN/m at 20° C.; (c) cooling the extrudate to form a cooled extrudate; and (d) pelletizing the cooled extrudate to form a plurality of polymer pellets. Provided is also a polymer pellet shipping system and a stable thermoplastic polymer pellet.
Claims20
A process for making thermoplastic propylene-based polymer pellets, comprising:
- (a) forming a polymer melt that consists of a propylene-based thermoplastic polymer having a Shore A hardness of less than 100 and a crystallinity of less than 40 J/g;
- (b) extruding the melt through a die to form a substantially continuous molten polymer extrudate, wherein the die has a contact surface bearing a polymer coating having a surface energy of less than 25 mN/m at 20° C.;
- (c) cooling the extrudate to form a cooled extrudate;
- and
- (d) pelletizing the cooled extrudate to form a plurality of polymer pellets, wherein the pelletizing takes place within a water bath, where the water bath temperature is in the range of about 40° C. to about 90° C. and where the water bath comprises a surfactant,
- wherein the surface of the polymer pellets have a crystallinity of about 15 J/g or more and a Shore A hardness of about 50 or more.
Dependencies are inferred from the claim text.