Extrusion apparatus having a driven feed segment

• US 20070082079A1
• Filed: 10/11/2005
• Published: 04/12/2007
• Est. Priority Date: 10/11/2005
• Status: Active Grant

• Current Assignee: Cryovac Incorporated (Sealed Air)
• Original Assignee: Cryovac Incorporated (Sealed Air)
• Inventors: Peavey, Jennifer S., Webster, Bradford
• Granted Patent: US 7,513,766 B2
• Time in Patent Office: Days
• US Class Current: 425/382.400
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/33 with parts rotatable relative to each other
• CPC Class Codes: B29C 48/335 Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular articles

Abstract

The invention is an extrusion apparatus having a driven feed segment that is rotatably driven about central mandrel or within a housing member. Rotation of the driven feed segment subjects one or more streams of resin introduced onto a surface thereof to transverse shear during radial flow. One of more driven feed segments can be assembled with other components of conventional extrusion die assemblies. Extrusion die assemblies can include one or more driven feed segments rotated in the same or opposite direction of each other. The number of streams of resin and rotational speed of the driven feed segment can be controlled to produce microlayered film having in excess of 4000 layers.

Claims

1. An extrusion apparatus comprising:

at least one driven feed segment having an outer circumference, a bore defining an inner circumference, and a first surface for receiving molten resin thereon; and

a support member upon which the at least one driven feed segment is rotatably disposed and wherein said driven feed segment is driven at a rate of rotation that is independent of a flow rate of a molten resin disposed thereon.

2. The extrusion apparatus according to claim 1, further comprising a central mandrel about which the driven feed segment is rotatably disposed, and an annular gap disposed between the inner circumference of the driven feed segment and the central mandrel, said annular gap defining an annular fluid pathway.

3. The extrusion apparatus according to claim 2, wherein the support member includes an inner circumferential wall and the annular gap is disposed between the inner circumferential wall and the outer circumference of the central mandrel.

4. The extrusion apparatus according to claim 3, wherein the inner circumferential wall includes a surface that is substantially coplanar with the first surface of the driven feed segment.

5. The extrusion apparatus according to claim 1, further comprising a housing member having a bore adapted to removably receive said driven feed segment therein.

6. The extrusion apparatus according to claim 5, further comprising an annular gap disposed between the driven feed segment and an inner circumference of the housing member, said annular gap defining an annular fluid pathway.

7. The extrusion apparatus according to claim 5, wherein the support member further comprises an outer circumferential wall and an annular gap is disposed between the housing member and the outer circumferential wall.

8. The extrusion apparatus according to claim 7, wherein the outer circumferential wall includes a surface that is substantially coplanar with the first surface of the driven feed segment.

9. The extrusion apparatus according to claim 1, further comprising a drive device that is in mechanical communication with said driven feed segment;

said drive device configured to rotatably drive said driven feed segment about said support member.

10. The extrusion apparatus according to claim 1, further comprising two or more driven feed segments.

11. The extrusion apparatus according to claim 1, comprising a first driven feed segment and a second driven feed segment, wherein first driven feed segment is rotated in a first direction and the second driven feed segment is rotated in the same or opposite direction of the first driven feed segment.

12. The extrusion apparatus according to claim 1, comprising a first driven feed segment and a second driven feed segment, wherein the first driven feed segment is rotated at one rotational speed and the second driven feed segment is rotated at the same or different rotational speed of the first driven feed segment.

13. The extrusion apparatus according to claim 1, further comprising at least two inlet ports that are configured to introduce two different melt streams onto the first surface of the driven feed segment.

14. The extrusion apparatus according to claim 1, further comprising at least one feed port capable of delivering fluid onto the first surface of the driven feed segment, said port in fluid communication with a molten resin source.

15. The extrusion apparatus according to claim 1, further comprising a plurality of feed ports in fluid communication with an extruder.

16. The extrusion apparatus according to claim 1, further comprising drive means for positively rotating at least one driven feed segment.

17. An extrusion assembly comprising:

a central mandrel;

at least one driven feed segment having a first surface for receiving a molten resin thereon and a bore rotatably disposed about said central mandrel and defining an annular gap therebetween;

a drive device cooperating with said at least one driven feed segment for rotatably driving said driven feed segment about said central mandrel; and

an orifice in communication with said annular gap so that resin passing through said annular gap exits said assembly.

18. The extrusion assembly according to claim 17, wherein rotation of the driven feed segment imparts a transverse shear field across the first surface of the driven feed segment.

19. The extrusion assembly according to claim 17, wherein rotation of the driven feed segment imparts a transverse shear field across an inner circumference of said bore.

20. The extrusion assembly according to claim 17, further comprising an end cap module, said end cap module having an inner surface opposite said first surface to define a radial gap therebetween.

21. The extrusion assembly according to claim 20, further comprising at least one feed port in fluid communication with said radial gap.

22. The extrusion assembly according to claim 17, wherein the drive device comprises a drive gear that is attached to a drive shaft and is in mechanical communication with a ring gear disposed on an outer circumference of the driven feed segment so that rotation of said drive shaft causes rotation of the driven feed segment.

23. The extrusion assembly according to claim 20, wherein the at least one driven feed segment is disposed in a modular support member.

24. An extrusion assembly comprising:

at least one driven feed segment having an outer circumference, a bore defining an inner circumference, and a first surface for receiving molten resin thereon;

a housing member having a circular bore in which at least one driven feed segment is rotatably disposed, the housing member defining an annular gap disposed between the driven feed segment and an inner circumference of the housing member, said annular gap defining an annular fluid pathway;

a support member disposed within said circular bore and upon which the at least one driven feed segment is rotatably disposed, and

an orifice in communication with said annular gap so that resin passing through said annular gap exits said assembly.

25. The extrusion assembly according to claim 24, further comprising a means for rotatably driving said driven feed segment within said housing member, said means comprising a molten resin flowing across the first surface of said driven feed segment, whereby flow of the molten resin on the surface of the driven feed segment imparts rotation thereto.

26. The extrusion assembly according to claim 24, further comprising a drive device cooperating with said at least one driven feed segment for rotatably driving said driven feed segment within said housing member.

27. The extrusion assembly according to claim 24, wherein the support member further comprises an outer circumferential wall having a surface that is substantially coplanar with the first surface of the driven feed segment, and wherein said annular gap is disposed between said housing member and the outer circumferential wall.

28. A method of extruding a thermoplastic article comprising:

introducing one or more streams of molten resin onto a surface of a driven feed segment that is rotatably disposed upon a support member;

rotating said driven feed segment to subject said one or more streams of resin to a transverse shear field;

advancing said molten resin across said surface in a radial pathway, said radial pathway being disposed between the surface of the driven feed segment and an inner surface of a stationary die module;

transferring said molten resin into an annular resin pathway to form a molten resin layer;

discharging said molten resin layer from an orifice that is in fluid communication with said annular resin pathway to form a molten extrudate; and

cooling said molten extrudate to a solid state to produce a thermoplastic article.

29. The method according to claim 28, wherein the step of rotating said driven feed segment further comprises rotating said driven feed segment about a central mandrel.

30. The method according to claim 28, wherein the step of introducing one or more streams of molten resin comprises introducing a plurality of streams of resin onto the surface of the driven feed segment.

31. The method according to claim 28, further comprising rotating the driven feed segment at a rate of rotation that is from about 1 to 50 revolutions per minute.

32. The method according to claim 28, further comprising rotating the driven feed segment at a rate of rotation that is in excess of about 10 revolutions per minute.

33. The method according to claim 28, wherein the annular resin pathway is disposed between an outer circumference of the driven feed segment and an inner circumference of the housing member, and wherein the step of rotating the driven feed segment comprises introducing a molten resin onto the surface of the driven feed segment to impart rotation thereto.