Process for introducing an additive into a polymer melt

• US 20070246867A1
• Filed: 04/20/2006
• Published: 10/25/2007
• Est. Priority Date: 04/20/2006
• Status: Active Grant

• Current Assignee: Bemis Company Incorporated (Amcor Plc)
• Original Assignee: Curwood Incorporated (Amcor Plc)
• Inventors: Siegel, Dan, Nelson, Kevin
• Granted Patent: US 7,993,560 B2
• Time in Patent Office: Days
• US Class Current: 264/510
• CPC Class Codes: B29B 7/94 Liquid charges
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/29 in liquid form
• CPC Class Codes: B29C 48/297 at several locations, e.g. using several hoppers or using a separate additive feeding
• CPC Class Codes: B29C 48/37 Gear pumps
• CPC Class Codes: B29C 48/397 using a single screw
• CPC Class Codes: B29C 48/405 Intermeshing co-rotating screws
• CPC Class Codes: B29C 48/76 Venting , drying means; Degassing means
• CPC Class Codes: B29C 48/762 Vapour stripping
• CPC Class Codes: B29K 2023/06 PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/0616 VLDPE, i.e. very low density polyethylene
• CPC Class Codes: B29K 2023/0625 LLDPE, i.e. linear low density polyethylene
• CPC Class Codes: B29K 2023/0633 LDPE, i.e. low density polyethylene
• CPC Class Codes: B29K 2023/065 HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2023/083 EVA, i.e. ethylene vinyl acetate copolymer
• CPC Class Codes: B29K 2023/086 EVOH, i.e. ethylene vinyl alcohol copolymer
• CPC Class Codes: B29K 2023/12 PP, i.e. polypropylene
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/0005 : containing compounding ingredients releasing, lubricating or separating agents B29C33/56, fibers B29K2105/08, B29K2105/12; fillers B29K2105/16, recycled material B29K2105/26
• CPC Class Codes: B29K 2105/0008 : Anti-static agents
• CPC Class Codes: B29K 2105/0032 : Pigments, colouring agents or opacifiyng agents
• CPC Class Codes: B29K 2105/0044 : Stabilisers, e.g. against oxydation, light or heat
• CPC Class Codes: C08J 3/226 : using a polymer as a carrier
• CPC Class Codes: Y10T 428/1352 : Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1359 : Three or more layers [continuous layer]

Abstract

A process includes introducing a base polymer into an extruder, heating to a temperature sufficient to form a polymer melt, introducing a liquid such as water including an additive with mixing and subsequent vaporization and venting of the liquid to produce an extrudate having a uniform distribution of preferably uniformly small additive particles.

Claims

1. A process comprising:

a) introducing at least one base polymer into an extruder;

b) heating the base polymer to a temperature sufficient to form a polymer melt;

c) introducing into the extruder a liquid comprising an additive;

d) mixing the liquid with the polymer melt in the extruder to form a blend;

e) vaporizing at least a portion of the liquid and removing it from the polymer melt; and

f) extruding the additive containing polymer through an extruder die.

2. The process of claim 1, wherein the base polymer is selected from the group consisting of polyolefin, polyethylene, polypropylene, ethylene vinyl acetate, EMA, EEA, EMAA, polybutene-1, and mixtures thereof.

3. The process of claim 1, wherein the additive is an NO donating compound.

4. The process of claim 1, wherein the additive is a salt.

5. The process of claim 1, wherein the additive is an inorganic salt.

6. The process of claim 1, wherein the additive in an undissolved state is a solid at 23°

C.

7. The process of claim 4, wherein the salt is selected from the group consisting of nitrite salts, nitrate salts, and mixtures thereof.

8. The process of claim 4, wherein the salt is selected from the group consisting of sodium nitrite, sodium nitrate, and mixtures thereof.

9. The process of claim 1, wherein the polymer is a polyester, ionomer, or nylon.

10. The process of claim 1, wherein the polymer is heated to a temperature above a melting point of the polymer.

11. The process of claim 1, wherein the polymer is an amorphous polymer and is heated to a temperature above a glass transition point of the polymer.

12. The process of claim 1, wherein the polymer is heated to a temperature above about 275°

F.

13. The process of claim 1, wherein the polymer is heated to a temperature less than 100°

F. above a melting point of the polymer.

14. The process of claim 1, wherein the liquid is water.

15. The process of claim 1, wherein the liquid comprises between about 20 wt % and about 60 wt % additive.

16. The process of claim 4, wherein the introduced liquid comprises between about 20 wt % and about 42 wt % salt.

17. The process of claim 4, wherein the introduced liquid comprises between about 30 wt % and about 40 wt % salt.

18. The process of claim 4, wherein a sufficient amount of the liquid is introduced into the polymer melt to obtain a blend comprising between about 2 wt % and about 10 wt % salt.

19. The process of claim 4, wherein a sufficient amount of the liquid is introduced into the polymer melt to obtain a blend comprising between about 4 wt % and about 6 wt % salt.

20. The process of claim 1, wherein at least 10 wt. % of the liquid is removed.

21. The process of claim 1, wherein at least 50 wt. % of the liquid is removed.

22. The process of claim 1, wherein at least 90 wt. % of the liquid is removed.

23. The process of claim 1, wherein at least 98 wt. % of the liquid is removed.

24. The process of claim 1, wherein the liquid is removed by venting.

25. The process of claim 1, wherein the liquid is removed by venting with a vacuum assist.

26. The process of claim 1 wherein the extruder includes a base polymer feed port and an injection port located at a position downstream of the base polymer feed port, wherein the solution is injected through the injection port.

27. The process of claim 26 wherein the extruder includes a vent located at a position downstream from the injection port, further comprising venting vapor through the vent.

28. The process of claim 27 further comprising providing at least restriction device downstream of the base polymer feed port and upstream of the solution feed port.

29. The process of claim 1 further comprising dissolving the additive in water to form the liquid.

30. The process of claim 1 further comprising dispersing the additive in water to form a solid in liquid dispersion or emulsion.

31. A pellet formed from the process of claim 1.

32. A thermoplastic flexible film formed from a thermoplastic polymer made by the process of claim 1.

36. The process of claim 32, wherein the salt is selected from the group consisting of sodium nitrite, sodium nitrate, and mixtures thereof.

33. A method of producing packaging for meat comprising:

introducing a first polymer into an extruder;

introducing a masterbatch of an additive containing polymer into the extruder to form a polymer blend;

wherein the masterbatch is made by

a) heating a base polymer to a temperature above a melting point of the base polymer to form a polymer melt;

b) introducing into the polymer melt a solution comprising a salt and water;

c) mixing the solution with the polymer melt in the extruder to form a blend;

d) allowing at least a portion of the water to vaporize and to vent from the extruder; and

e) extruding the blend to form the masterbatch; and

forming a packaging film from the masterbatch containing blend; and

fabricating the film into a package, wherein the film forms an inner layer of the package.

34. The process of claim 33, wherein the base polymer is selected from the group consisting of polyolefin, polyethylene, polypropylene, ethylene vinyl acetate, EEA, EMA, EMAA, polybutene-1, and mixtures thereof.

35. The process of claim 33, wherein the salt is selected from the group consisting of nitrite salts, nitrate salts, and mixtures thereof.

37. The process of claim 33, wherein a sufficient amount of the solution is introduced into the polymer melt to obtain a film comprising between about 0.05 wt % and about 5 wt % salt.

38. The process of claim 33, wherein a sufficient amount of the solution is introduced into the polymer melt to obtain a film comprising between about 0.1 wt % and about 2.5 wt % salt

39. A package formed from the process of claim 33.