Post Consumer Scrap Film Recycling Process

• US 20130186573A1
• Filed: 03/12/2013
• Published: 07/25/2013
• Est. Priority Date: 02/09/2011
• Status: Active Grant

• Current Assignee: Wisconsin Film & Bag, Inc.
• Original Assignee: Wisconsin Film & Bag, Inc.
• Inventors: Kulesa, Robert Francis, Feeney, James J., Carlstedt, Richard Wayne, Blake, Daniel William, Hacker, Buckell Gary, Johnson, Abby Marie
• Granted Patent: US 8,820,666 B2
• Time in Patent Office: Days
• US Class Current: 156/701
• CPC Class Codes: B02C 23/08 Separating or sorting of material, associated with crushing or disintegrating B02C23/18 takes precedence ; beater mills combined with sifting devices B02C13/13, B02C13/14; for tumbling mills B02C17/1835
• CPC Class Codes: B02C 23/40 with more than one means for adding fluid to the material being crushed or disintegrated
• CPC Class Codes: B29B 17/0026 by agglomeration or compacting
• CPC Class Codes: B29B 17/04 Disintegrating plastics, e.g. by millingB29B9/02, B29B11/02, B29B13/10, B29B17/02 take precedence
• CPC Class Codes: B29B 2017/0015 Washing, rinsing
• CPC Class Codes: B29B 2017/0289 Washing the materials in liquids
• 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 2105/065 containing impurities
• CPC Class Codes: B29L 2007/008 Wide strips, e.g. films, webs
• CPC Class Codes: B32B 38/10 Removing layers, or parts of layers, mechanically or chemically
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling
• CPC Class Codes: Y10T 156/11 Methods of delaminating, per se; i.e. , separating at bonding face

Abstract

A method for processing a supply of post consumer scrap linear low density or low density polyethylene film into near-virgin quality blown film product. The method includes tearing the supply of film in a shredder, wherein the surface area of the film is exposed, including delaminating the film. The torn supply of film is washed in a water bath including a surfactant. The film is agitated in the bath containing the surfactant wherein contaminants on the film are removed from the film. The washed film is ground into smaller pieces and additional washing of the ground film in a rotating friction washer occurs wherein additional contaminants are removed from the film. The ground film is then dried and compacted without addition of water into granulated objects of near-virgin quality blown film product.

Claims

1. A method for processing a supply of post consumer scrap linear low density polyethylene film or low density polyethylene film into near-virgin quality blown film product, comprising:

tearing the supply of film in a shredder, wherein surface area of the film is exposed, including delaminating the film;

washing the torn film in a water bath with a detergent having a surfactant and agitating the film in the bath, wherein contaminates are removed from the film;

grinding the film and washing the ground film in a rotating friction washer, wherein additional contaminates are removed from the film;

washing the film in a postwash sink float water bath, with the film subjected to mechanical and hydraulic agitation;

drying the ground film; and

compacting the dry ground film, without addition of water, into granulated objects of near-virgin quality blown film product.

2. The method for processing the supply of film of claim 1, further comprising the postwash sink float water bath comprises:

a water tank configured to hold water;

at least one paddlewheel in fluid communication with the water;

a baffle honeycomb in the water tank proximate the tank bottom;

a water spray system coupled to the water tank and extending over the water with a plurality of spray bars configured to direct water jets into the water in the water tank; and

a waterfall separator configured to move the film to a discharge auger configured to remove the film from the postwash sink float water bath.

3. The method for processing the supply of film of claim 1, wherein the water bath includes at least one turbowasher and at least one friction washer.

4. The method for processing the supply of film of claim 3, wherein at least one of the washers contains hot water.

5. The method for processing the supply of film of claim 4 wherein the hot water is at least 140°

F. and not more than 190°

F.

6. The method for processing the supply of film of claim 1, further comprising detecting metal from the supply of film and includes subjecting the supply of film to a magnetic field to identify ferrous metal.

7. The method for processing the supply of film of claim 6, further comprising removing detected metal including one of machine removal and manual removal.

8. The method for processing the supply of film of claim 1, wherein the dry ground plastic film contains not more than 10%, by weight, water content.

9. The method for processing the supply of film of claim 1, further comprising forming the granulated objects into pellets after the compacting step.

10. The method for processing the supply of film of claim 1, wherein the detergent comprises a mixture, in addition to the surfactant, of a caustic soda, a soda ash, and a sodium percarbonate.

11. The method for processing the supply of film of claim 10, wherein the surfactant is a nonionic surfactant, the caustic soda is a sodium hydroxide, and to soda ash is sodium carbonate.

12. The method for processing the supply of film of claim 11, wherein the nonionic surfactant is low foaming linear alcohol alkoxylate.

13. A method for processing post consumer scrap film into a near-virgin quality blown film product, the method comprising:

providing one of a supply of recyclable linear low density polyethylene plastic film and a supply of recyclable low density polyethylene plastic film;

removing metal from the supply of plastic film;

shredding the supply of plastic film after metal removal, wherein the plastic film is torn exposing surface area of film;

discharging the shredded plastic film through a filter screen to a water bath;

agitating the water in the water bath to wet all the surfaces of the shredded plastic film;

removing the plastic film from the water bath;

wet grinding the plastic film;

washing the ground plastic film in a rotating friction washer, wherein contaminates are removed from the plastic film;

separating at least two different types of the washed ground plastic film in a hydrocyclone, wherein lighter plastic film is separated from heavier plastic film;

washing lighter plastic film in a postwash sink float water bath, with the film subjected to mechanical and hydraulic agitation;

drying the washed ground plastic film; and

compacting the dry ground plastic film without addition of water into granulated objects of near-virgin quality plastic film, wherein the granulated objects are one of stored and used as raw material in a blown film operation.

14. The method for processing post consumer scrap film of claim 13, further comprising adding an additive to the water bath.

15. The method for processing post consumer scrap film of claim 14, wherein the additive is a detergent.

16. The method for processing post consumer scrap film of claim 15, wherein the detergent comprises a mixture, in addition to the surfactant, of a caustic soda, and a soda ash as a sodium percarbonate.

17. The method for processing post consumer scram film of claim 16, wherein the surfactant is a nonionic surfactant, the caustic soda is sodium hydroxide, and to soda ash is sodium carbonate.

18. The method for processing post consumer scrap film of claim 17, wherein the nonionic surfactant is low foaming linear alcohol alkoxylate.

19. The method for processing the supply of film of claim 13, further comprising the postwash sink float water bath comprises:

a water tank configured to hold water;

at least one paddlewheel in fluid communication with the water;

a baffle honeycomb in the water tank proximate the tank bottom;

a water spray system coupled to the water tank and extending over the water with a plurality of spray bars configured to direct water jets into the water in the water tank; and

a waterfall separator configured to move the film to a discharge auger configured to remove the film from the postwash sink float water bath.

20. The method for processing post consumer scrap film of claim 13, wherein the water bath includes at least one turbowasher and at least one friction water.

21. The method for processing post consumer scrap film of claim 20, wherein at least one of the washers contains hot water.

22. The method for processing post consumer scrap film of claim 21, wherein the hot water is at least 140°

F., but not more than 190°

F.

23. The method for processing post consumer scrap film of claim 13, wherein the removing metal includes subjecting the supply of plastic film to a magnetic field to identify ferrous metal.

24. The method for processing post consumer scrap film of claim 13, wherein the dry ground plastic film contains not more than 10%, by weight, water content.

25. The method for processing post consumer scrap film of claim 13, wherein the removing metal includes one of washing lighter plastic film in a postwash sink float water bath machine removal and manual removal.

26. The method for processing post consumer scrap film of claim 13, further comprising forming the granulated objects into pellets after the compacting step.

27. A method for processing post consumer scrap film into a near-virgin quality blown film product, the method comprising:

providing one of a supply of recyclable linear low density polyethylene plastic film and a supply of recyclable low density polyethylene plastic film;

removing metal from the supply of plastic film;

shredding the supply of plastic film after metal removal, wherein the plastic film is torn exposing surface area of film;

discharging the shredded plastic film through a filter screen to a water bath;

agitating the water in the water bath to wet all the surfaces of the shredded plastic film, the water bath including a surfactant additive, a detergent, an oxidizer, and a bleaching agent;

removing the plastic film from the water bath;

wet grinding the plastic film;

washing the ground plastic film in a rotating friction washer, wherein contaminates are removed from the plastic film;

separating at least two different types of the washed ground plastic film in a hydrocyclone, wherein lighter plastic film is separated from heavier plastic film;

washing lighter plastic film in a postwash sink float water bath with the film subjected to mechanical and hydraulic agitation;

drying the washed ground plastic film so the film contains not more than 10%, by weight, water content; and

compacting the dry ground plastic film without addition of water into granulated objects of near-virgin quality plastic film, wherein the granulated objects are one of stored and used as raw material in a blown film operation.

28. The method for processing post consumer scrap film of claim 27, further comprising forming the granulated objects into pellets after the compacting step.

29. The method for processing the supply of film of claim 27, further comprising the postwash sink float water bath comprises:

a water tank configured to hold water;

at least one paddlewheel in fluid communication with the water;

a baffle honeycomb in the water tank proximate the tank bottom;

a water spray system coupled to the water tank and extending over the water with a plurality of spray bars configured to direct water jets into the water in the water tank; and

a waterfall separator configured to move the film to a discharge auger configured to remove the film from the postwash sink float water bath.

30. The method for processing post consumer scrap film of claim 27, wherein the surfactant is a nonionic surfactant.

31. The method for processing post consumer scrap film of claim 30, wherein the nonionic surfactant is low foaming linear alcohol alkoxylate.