Method and device for recycling pet materials

• US 6,784,214 B1
• Filed: 03/22/2002
• Issued: 08/31/2004
• Est. Priority Date: 09/22/1999
• Status: Expired due to Term

• Current Assignee: Georg Wendelin, Helmut Bacher, Helmuth Schulz
• Original Assignee: Georg Wendelin, Helmut Bacher, Helmuth Schulz
• Inventors: Schulz, Helmuth, Wendelin, Georg, Bacher, Helmut
• Primary Examiner(s): Acquah, Samuel A.
• Application Number:
  US10/088,951
• Time in Patent Office: 893 Days
• Field of Search: 521/48, 526/65, 528/503
• US Class Current: 521/48
• CPC Class Codes: B29B 13/06 by drying B29B13/08 takes precedence ; drying moulded articles or half products B29C37/0092
• CPC Class Codes: B29B 17/00 Recovery of plastics or other constituents of waste material containing plastics; volume reduction of waste plastics, e.g. by mechanical compacting or melting disposal of solid waste B09B; chemical recovery C08J11/00
• CPC Class Codes: B29B 2017/048 Cutter-compactors, e.g. of the EREMA type
• CPC Class Codes: B29C 2791/001 Shaping in several steps
• CPC Class Codes: B29C 2948/922 Viscosity; Melt flow index [MFI]; Molecular weight
• CPC Class Codes: B29C 2948/92428 Calibration, after-treatment, or cooling zone
• CPC Class Codes: B29C 2948/92514 Pressure
• CPC Class Codes: B29C 2948/92561 Time, e.g. start, termination, duration or interruption
• CPC Class Codes: B29C 2948/92704 Temperature
• CPC Class Codes: B29C 2948/92895 Barrel or housing
• CPC Class Codes: B29C 2948/92914 Degassing unit
• CPC Class Codes: B29C 48/0018 combined with shaping by orienting, stretching or shrinking, e.g. film blowing B29C48/0017 takes precedence
• CPC Class Codes: B29C 48/04 Particle-shaped making granules B29B9/00
• CPC Class Codes: B29C 48/277 of materials
• CPC Class Codes: B29C 48/92 Measuring, controlling or regulating
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: C08J 11/06 without chemical reactions
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling

Abstract

Within a process for recycling of PET-material and/or objects of PET, the PET-material to be processed is heated and dried in the course of a pre-treatment step and simultaneously is crystallized at elevated temperature. This pre-treatment step is followed by a main-treatment step under vacuum. In this main-treatment step, the processed material is again dried and crystallized at a temperature that is higher than the temperature of the pre-treatment step. Preferably, also in the main-treatment step no plasticizing of the material takes place; the plasticizing or, respectively, melting of the material takes place only after the main-processing step.

An apparatus for performing this process comprises a pre-processing device (3) in which the processed material is dried and simultaneously crystallized at elevated temperature, and, if desired, is also comminuted. A main-processing device (4) is connected to this pre-processing device (3), in which main-processing device the supplied PET-material is dried, crystallized and heated to a temperature that is higher than the temperature within the pre-treatment device.

Claims

1. Process for recycling of PET-material, in which the PET-material to be processed is heated by movement and thereby is dried, crystallized and at least one of plasticized and molten, and subsequently is processed to one of PET-granulate and PET-articles, characterized in that the supplied PET-material is processed in first and second steps, wherein in the first step the PET-material is subjected to a pre-processing by subjecting it to mechanical power and thereby heating it and drying it at an elevated temperature, and simultaneously crystallizing it, and that then within the second step that precedes plasticizing or melting, the PET-material is subjected to a main processing in which the PET-material under vacuum conditions is again dried and further crystallized by subjecting it to mechanical power, wherein the main processing is performed at a temperature that is increased when compared with the pre-processing.

2. Process according to claim 1, characterized in that the material to be processed is at least one of pre-comminuted, washed and pre-dried before the pre-processing step.

3. Process according to claim 1, characterized in that the temperature of the main-processing step is kept below the plasticizing temperature of the PET-material.

4. Process according to claim 1, characterized in that for PET-pieces and/or milled PET-bottles, the pre-processing step is performed under environmental pressure at a temperature range of 140 to 190°

C. and at simultaneous mechanical treatment or, respectively, applying power that causes heating, by means of at least one mixing and/or comminuting element, wherein the average dwell-time of the PET-material or, respectively, the duration of pre-processing, amounts to 35 to 65 min.

5. Process according to claim 1, characterized in that for PET-foils and/or PET-fibers and/or PET-flakes, the pre-processing step is performed under environmental pressure at a temperature range of 170 to 200°

C. and at simultaneous mechanical treatment or, respectively, applying power that causes heating, by means of at least one mixing and/or comminuting element, wherein the average dwell-time of the PET-material or, respectively, the duration of pre-processing, amounts to 10 to 30 min.

6. Process according to claim 1, characterized in that the PET-material is subjected to the pre-processing step in a continuous flow.

7. Process according to claim 1, characterized in that the pre-processed PET-material is subjected to an intermediate storage between the pre-processing step and the main-processing step, the duration of the storage corresponds to 80 to 120% of the duration of pre-processing step, and the pre-processed PET-material is kept during the intermediate storage and/or during conveying to main processing at a temperature that is between 130 to 190°

C.

8. Process according to claim 1, characterized in that the main-processing step is performed under a pressure of less than 20 mbar, and the pre-processed PET-pieces and/or the milled bottle material is one of mechanically treated at a temperature of 170 to 210°

C. and subjected to a power introduction that causes heating by at least one mixing and/or comminuting element, wherein the average dwell-time of the PET-material or the duration of the main-processing step, respectively, amounts to 40 to 100 min.

9. Process according to claim 8, characterized in that the main processing is performed at a pressure of less than 10 mbar.

10. Process according to claim 1, characterized in that the main-processing step is performed under vacuum, and the pre-processed PET-foils and/or PET-fibers are processed at one of a temperature of 160 to 210°

C. and by subjecting them to a mechanical power introduction that causes heating by at least one mixing and/or comminuting element, wherein the average dwell-time of the PET-material or the duration of the main-processing step, respectively, amounts to 5 to 25 min.

11. Process according to claim 10, characterized in that the main-processing step is performed at a pressure less than 150 mbar.

12. Process according to claim 5, characterized in that at least one rotating mixing and/or comminuting element is used.

13. Process according to claim 1, characterized in that the PET-material is comminuted before pre-processing to sizes of 15 to 25 mm.

14. Process according to claim 1, characterized in that the PET-material to be processed is pre-comminuted and/or washed and/or pre-dried before the preprocessing step.

15. Process according to claim 1, characterized in that the PET-material is supplied from a main-processing apparatus to the extruder under vacuum conditions.

46. A process according to claim 1 including filtering the PET-material before it is processed to one of PET-granulate and PET-articles.

16. Process for recycling of PET-material, in which the PET-material to be processed is heated by movement and thereby is dried and thereafter is one of plasticized and molten, wherein the PET-material is initially processed in first and second steps, wherein in the first step the PET-material is pre-processed by subjecting it to mechanical power to thereby heat and dry it at an elevated temperature, and wherein thereafter in the second step the PET-material is subjected to a main processing in which the PET-material is dried under vacuum conditions by again subjecting it to mechanical power, wherein the PET-material in the first step is crystallized simultaneously with drying, and wherein the PET-material in the second step is further crystallized, the second step being performed at a temperature that is higher than the temperature during the first step, and wherein, after the PET-material has been one of plasticized and molten, it is processed into one of a PET-granulate and PET-articles.

17. Process according to claim 16, including at least one of pre-comminuting, washing and pre-drying the PET-material before pre-processing it.

18. Process according to claim 16, including keeping the temperature of the main processing below a plasticizing temperature of the PET-material.

19. Process according to claim 16, wherein the PET-material comprises at least one of PET-pieces and milled PET-bottles, and wherein the pre-processing is performed at a temperature range between 140 to 190°

C. by at least one of a mechanical treatment and applying power that causes heating and employs at least one of a mixing element and a comminuting element, and wherein at least one of an average dwell-time of the PET-material and/or duration of the pre-processing amounts to 35 to 65 min.

20. Process according to claim 19, wherein the temperature range of pre-processing is between 150 to 160°

C. and the duration of pre-processing is 40 to 60 min.

21. Process according to claim 16, wherein the PET-material comprises at least one of a PET-foil, PET-fibers and PET-flakes, wherein the pre-processing is performed at a temperature range of 170 to 200°

C. by at least one of a mechanical treatment and applying power that causes heating and employing at least one of a mixing element and a comminuting element, and wherein at least one of an average dwell-time of the PET-material and duration of the pre-processing amounts to 10 to 30 min.

22. Process according to claim 21, wherein the temperature range for pre-processing is between 180 to 200°

C. and the duration of the pre-processing amounts to 10 to 15 min.

23. Process according to claim 16, wherein the pre-processing is performed under a vacuum.

24. Process according to claim 19, wherein the pre-processing is performed under ambient pressure.

25. Process according to claim 16, including causing contaminants included in the PET-material to escape by using extended dwell-times during pre-processing.

26. Process according to claim 16, wherein pre-processing is performed by subjecting the PET-material to a continuous flow.

27. Process according to claim 16, including subjecting the pre-processed PET-material to an intermediate storage between the pre-processing and the main processing for a duration between 80 to 120% of the duration of pre-processing, and keeping the pre-processed PET-material during at least one of the intermediate storage and conveying it to the main processing at a temperature that is substantially constant.

28. Process according to claim 27, including keeping the temperature during the at least one of the intermediate storage and conveying it to the main processing between 130 to 190°

C.

29. Process according to claim 28, wherein the temperature is kept between 150 to 170°

C.

30. Process according to claim 16, including performing the main processing under vacuum, wherein the PET-material comprises at least one of pre-processed PET-pieces and milled bottle material and is one of mechanically treated at a temperature of between 170 to 210°

C. and subjected to a power introduction that causes heating with at least one of a mixing element and a comminuting element, and wherein an average dwell-time of the PET-material or the duration of the main processing amounts to between 40 to 100 min.

31. Process according to claim 30, wherein the main processing is performed under a pressure of less than 20 mbar.

32. Process according to claim 30, wherein main processing is performed under a pressure of less than 10 mbar.

33. Process according to claim 30, wherein the mechanical treatment is performed at a temperature of between 180 to 200°

C.

34. Process according to claim 30, wherein the duration of main processing is between 50 to 90 min.

35. Process according to claim 21, wherein the main processing is performed under a vacuum, wherein, during the main processing, the pre-processed at least one of PET-foils and PET-fibers are subjected to one of at a temperature between 160 to 210°

C. and a mechanical power introduction that causes heating with at least one of a mixing element and a comminuting element, and wherein one of the average dwell-time of the PET-material and the duration of the main processing amounts to 5 to 25 min.

36. Process according to claim 35, wherein the pre-processed at least one of PET-foils and PET-fibers are main-processed at a temperature between 170 to 205°

C.

37. Process according to claim 35, wherein the duration of the main processing amounts to between 10 to 15 min.

38. Process according to claim 35, wherein the main processing is performed at a pressure of less than 150 mbar.

39. Process according to claim 38, wherein the main processing is performed at a pressure of less than 50 mbar.

40. Process according to claim 16, wherein subjecting the PET-material to mechanical power comprises using at least one of a rotating mixing element and a rotating comminuting element.

41. Process according to claim 16, including at least one of pre-comminuting, washing and pre-drying the PET-material prior to pre-processing.

42. Process according to claim 41, including comminuting the PET-material prior to pre-processing to particle sizes between 15 to 25 mm.

43. Process according to claim 16, including supplying the PET-material from a main-processing apparatus to an extruder under a vacuum.

44. Process according to claim 43, wherein the vacuum exists within the main-processing apparatus and extends into an inlet section of the extruder.

45. Process according to claim 16, including filtering the PET-material after plasticizing or melting.