Method for use in packaging and/or storing atactic polypropylene or other amorphous poly alpha olefins

• US 5,403,528 A
• Filed: 08/21/1992
• Issued: 04/04/1995
• Est. Priority Date: 04/26/1988
• Status: Expired due to Term

• Current Assignee: Rextac Llc
• Original Assignee: Rexene Corp. (Huntsman Corporation)
• Inventors: Fowler, J. Nick
• Primary Examiner(s): Woo, Jay H.
• Assistant Examiner(s): Davis, Robert B.
• Application Number:
  US07/934,869
• Time in Patent Office: 956 Days
• Field of Search: 264/37, 264/130, 264/131, 264/142, 264/237, 264/517, 425/90, 425/92, 425/96, 425/104, 425/308, 425/310, 425/311, 425/313, 425/445, 425/377, 425/378.1, 427/180, 427/189, 427/398.1, 427/421, 427/427, 118/309, 118/312
• US Class Current: 264/130
• CPC Class Codes: B29B 9/06 in the form of filamentary material, e.g. combined with extrusion
• CPC Class Codes: B29B 9/16 Auxiliary treatment of granules
• CPC Class Codes: C08J 2323/12 Polypropene
• CPC Class Codes: C08J 3/124 Treatment for improving the free-flowing characteristics

Abstract

Packaging and/or storing atactic polypropylene or other amorphous poly alpha olefins is accomplished by first heating a mass of the olefin material to a molten state and then cooling the molten mass of olefin material to an extrusion temperature. Next, the formless mass of atactic polypropylene is extruded and cut into a succession of pellets. Inert dust-like material is sprayed onto the cutting surfaces and the surface of the olefin material so that the natural tendency of the material to stick to itself and to other objects is avoided.

Claims

1. A method for processing an amorphous poly alpha olefin comprising the steps of:

cooling a molten mass of the amorphous poly alpha olefin to an extrusion temperature;

extruding the cooled amorphous poly alpha olefin through an orifice of an extrusion head;

reciprocating a cutter across the orifice to cut the extruded amorphous poly alpha olefin into a succession of pellets;

substantially covering the pellets with dust particles inert to the amorphous poly alpha olefin as the pellets pass through the orifice;

removing the excess dust particles from the pellets; and

cooling the pellets after removal of the dust particles therefrom.

2. The method as in claim 1, further comprising the steps of:

heating the amorphous poly alpha olefin to a molten condition at approximately 375°

F.; and

cooling the amorphous poly alpha olefin to approximately 200°

F. prior to extrusion through the orifice.

3. The method as in claim 1, further comprising the steps of:

extruding the cooled amorphous poly alpha olefin in an enclosure adjacent to the extrusion head to surround the pellets and the cutter, and

blowing the dust particles into the enclosure to substantially cover the pellets and the cutter.

4. The method as in claim 3, further including the step of:

recovering the dust particles for reuse in the enclosure.

5. The method as in claim 1, wherein the dust particles comprise polypropylene.

23. The method as in claim 1, wherein the dust particles comprise polyethylene.

6. A method for processing an amorphous poly alpha olefin comprising the steps of:

cooling a molten mass of the amorphous poly alpha olefin to an extrusion temperature;

extruding the cooled amorphous poly alpha olefin through a plurality of orifices in an extrusion head;

cutting the extruded amorphous poly alpha olefin into a succession of pellets by reciprocating a knife across the orifices;

mixing dust particles inert to the amorphous poly alpha olefin with water and a surfactant to form a slurry containing at least 75% by volume of dust particles;

substantially covering the pellets with the slurry of dust particles as the pellets pass through the orifices;

removing the excess slurry of dust particles from the pellets; and

cooling the pellets after removal of the slurry of dust particles therefrom.

7. The method as in claim 6, further comprising the steps of:

extruding the cooled amorphous poly alpha olefin in an enclosure adjacent to the extrusion head to surround the pellets and the knife; and

blowing the slurry of dust particles into the enclosure to substantially cover the pellets and the knife.

8. The method as in claim 7, further including the step of:

recovering the slurry to be returned for reuse in the enclosure.

9. The method as in claim 6, wherein the dust particles comprise amorphous polypropylene.

10. The method as in claim 6, wherein the step of extruding the cooled amorphous poly alpha olefin includes the step of extruding the amorphous poly alpha olefin through an opening in the knife.

24. The method as in claim 6, where the dust particles comprise polyethylene.

11. A method for processing an amorphous poly alpha olefin comprising the steps of:

heating the amorphous poly alpha olefin to a molten temperature;

cooling the amorphous poly alpha olefin to an extrusion temperature;

extruding the cooled amorphous poly alpha olefin through a plurality of orifices in an extrusion head;

cutting the extruded amorphous poly alpha olefin into a succession of pellets by reciprocating a knife across the orifices;

substantially covering the pellets with dust particles inert to the amorphous poly alpha olefin as the pellets pass through the orifice;

removing the excess dust particles from the pellets; and

cooling the pellets after removal of the excess dust particles therefrom.

12. The method as in claim 11, further including the step of:

reheating the amorphous poly alpha olefin during periods of non-extrusion.

13. An apparatus for processing an amorphous poly alpha olefin comprising:

means for cooling a mass of molten amorphous poly alpha olefin;

means for extruding the cooled amorphous poly alpha olefin through an orifice;

a knife for cutting the extruded amorphous poly alpha olefin;

means for reciprocating the knife across the orifice of the extruding means, said knife cutting the extruded amorphous poly alpha olefin into a succession of pellets;

means for spraying dust particles inert to the amorphous poly alpha olefin onto the pellets;

means for removing excess dust particles from the pellets;

means for capture and reuse of the removed dust particles; and

means for cooling the pellets after removal of the excess dust particles.

14. The apparatus of claim 13, wherein the extruding means includes:

a receiving chamber where the amorphous poly alpha olefin is held prior to extrusion;

an extrusion head for extruding amorphous poly alpha olefin from the receiving chamber;

a valve for the control of amorphous poly alpha olefin flow through the extrusion head; and

a plurality of orifices within the extrusion head.

15. The apparatus of claim 13, wherein the means for reciprocating the knife across the orifice includes a control means for varying the knife reciprocation rate.

16. The apparatus of claim 13, wherein the knife is mounted laterally across the orifice of the extrusion head, said knife having an opening through which the amorphous poly alpha olefin is extruded.

17. The apparatus of claim 16, wherein the knife includes cutting edges on the upper and lower edges of the opening for cutting a pellet of the extruded amorphous poly alpha olefin during each reciprocation stroke of the knife.

18. The apparatus of claim 13, wherein the means for spraying dust particles onto the pellets includes:

a nozzle for applying the dust particles to the pellets;

a hose for supplying the dust particles to the nozzle;

support means to position the nozzle to spray the inert dust particles onto the pellets; and

an enclosure substantially surrounding the nozzle and the extrusion orifice.

19. The apparatus of claim 13, wherein the means for capture and reuse of the dust particles includes:

a holding tank for holding the dust particles;

a capture receptacle, positioned below the means for removing, for collecting excess dust particles removed from the pellets; and

a conduit for returning the dust particles from the capture receptacle to the holding tank.

20. The apparatus of claim 13, wherein the means for cooling the pellets includes a water bath.

22. The apparatus of claim 13 wherein the means for removing comprises a shaker for shaking the dusted pellets to remove the excess dust particles.

21. An apparatus for processing an amorphous poly alpha olefin comprising:

means for heating a mass of the amorphous poly alpha olefin;

a heat exchanger for cooling a molten mass of the amorphous poly alpha olefin;

an extrusion head including a plurality of orifices for extruding the cooled amorphous poly alpha olefin;

a reciprocating knife mounted laterally across the plurality of orifices of the extrusion head to cut the extruded amorphous poly alpha olefin into a succession of pellets;

an enclosure substantially surrounding the extrusion head and including at least one nozzle and at least one hose for spraying a slurry of dust particles inert to the amorphous poly alpha olefin onto the pellets;

means for removing and capturing the excess slurry of dust particles from the pellets; and

a water bath for cooling the pellets after removal of the excess slurry of dust particles.