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US 12,747,331 B2Granted
Combined washing/delamination process for multilayer film-containing recycling streams
AssigneeBorealis AG
InventorsPeter Denifl, Kilian Piettre, Bernadette Duscher, Auli Nummila-Pakarinen, Peter Niedersüss, Anthony Berthelier, Andreas Nagl
Life of this patent
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Abstract
A method for achieving the simultaneous washing/delamination of multilayer films via treatment with an alkaline aqueous solution during a mechanical recycling process, thereby improving the yield and/or purity of a desired polyolefin.
Claims18
A process for treating a polyolefin mixed recycling stream (A1), comprising, in the given order, the steps of:
- a1) providing a polyolefin mixed recycling stream (A1), wherein the polyolefin mixed recycling stream (A1) comprises:
- i) multilayer films (F1) comprising the following layers:
- (a) an outer layer consisting of a desired polyolefin (PO);
- (b) a metal layer in contact with the outer layer (a);
- and
- (c) one or more further layers wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain the desired polyolefin (PO), polyolefin other than the desired polyolefin, or non-polyolefin material;
- ii) monolayer films of the desired polyolefin (PO), and
- iii) optionally multilayer films (F2) consisting of the following layers:
- (a) an outer layer consisting of a desired polyolefin (PO);
- and
- (b) a metal layer in contact with the outer layer (a),
- b1) selecting those pieces present in the polyolefin mixed recycling stream (A1) that are either monolayer film pieces of the desired polyolefin (PO) or pieces of multilayer films (F1) or pieces of multilayer films (F2) as defined in step a1) and separating and collecting these pieces to form a recycling stream (B1) enriched in the desired polyolefin (PO);
- c1) milling, shredding or grinding the recycling stream (B1) enriched in the desired polyolefin (PO) to convert any pieces that are not in flaked form into flakes with a flake surface area in the range from 50 to 2500 mm2, thereby obtaining a recycling stream (B1) enriched in the desired polyolefin (PO) in flaked form;
- d1) treating the recycling stream (B1) enriched in the desired polyolefin (PO) in flaked form with an alkaline aqueous solution, thereby obtaining a treated recycling stream (C) dispersed in the alkaline aqueous solution;
- e1) removing the alkaline aqueous solution, thereby obtaining the treated recycling stream (C);
- f1) rinsing the treated recycling stream (C) with solvent, thereby removing all residue of the alkaline aqueous solution to obtain a rinsed recycling stream (D);
- g1) selecting those flakes present in the rinsed recycling stream (D) that contain any material other than the desired polyolefin (PO) and removing these flakes from the treated recycling stream to leave a remaining recycling stream (E) of the desired polyolefin (PO);
- and
- h1) optionally extruding and pelletizing the recycling stream (E) of the desired polyolefin (PO) to form pellets (P) of the desired polyolefin (PO),
- wherein step c1) can be omitted in the case that the pieces of the recycling stream (B1) enriched in the desired polyolefin (PO) are already in flaked form with a flake surface area in the range from 50 to 2500 mm2,
- wherein the desired polyolefin (PO) is selected from the group consisting of polypropylene and polyethylene.
18 more elements
A process for treating a recycling stream (B2) enriched in a desired polyolefin (PO), comprising, in the given order, the steps of:
- a2) providing a recycling stream (B2) enriched in the desired polyolefin (PO), wherein the recycling stream (B2) comprises:
- i) multilayer films (F1) comprising the following layers:
- (a) an outer layer consisting of the desired polyolefin (PO);
- (b) a metal layer in contact with the outer layer (a);
- and
- (c) one or more further layers wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain the desired polyolefin (PO), polyolefin other than the desired polyolefin, or non-polyolefin material,
- ii) monolayer films of the desired polyolefin (PO), and
- iii) optionally multilayer films (F2) consisting of the following layers:
- (a) an outer layer consisting of a desired polyolefin (PO);
- and
- (b) a metal layer in contact with the outer layer (a),
- wherein the recycling stream (B2) enriched in the desired polyolefin (PO) is provided in flaked form, and
- wherein the recycling stream (B2) enriched in the desired polyolefin (PO) is obtainable by a process comprising the steps, in the given order, of selecting those pieces present in a precursor polyolefin mixed recycling stream (A2) that are either monolayer film pieces of the desired polyolefin (PO) or pieces of multilayer films (F1) or multilayer films (F2) as defined above and separating and collecting these pieces to form the recycling stream (B2) enriched in the desired polyolefin (PO);
- b2) treating the recycling stream (B2) enriched in the desired polyolefin (PO) in flaked form with an alkaline aqueous solution, thereby obtaining a treated recycling stream (C) dispersed in the alkaline aqueous solution;
- c2) removing the alkaline aqueous solution, thereby obtaining the treated recycling stream (C);
- d2) rinsing the treated recycling stream (C) with solvent thereby removing all residue of the alkaline aqueous solution to obtain a rinsed recycling stream (D);
- e2) selecting those flakes present in the rinsed recycling stream (D) that contain any material other than the desired polyolefin (PO) and removing these flakes from the treated recycling stream to leave a remaining recycling stream (E) of the desired polyolefin (PO);
- and
- f2) optionally extruding and pelletizing the recycling stream (E) of the desired polyolefin (PO) to form pellets (P) of the desired polyolefin (PO),
- wherein the desired polyolefin (PO) is selected from the group consisting of polypropylene and polyethylene.
17 more elements
A process for treating a polyolefin mixed recycling stream (B3), comprising, in the given order, the steps of:
- a3) providing a polyolefin mixed recycling stream (B3) that comprises at least 50 wt.-%, relative to the total weight of the polyolefin mixed recycling stream (B3), of multilayer films (F1) and optionally multilayer films (F2),
- wherein the multilayer films (F1) comprise the following layers:
- (a) an outer layer consisting of a polyolefin (PO);
- (b) a metal layer in contact with the outer layer (a);
- and
- (c) one or more further layers wherein at least one of the one or more further layers is in contact with the metal layer (b), wherein the one or more further layers may contain the polyolefin (PO) of the outer layer (a), polyolefin other than the polyolefin of the outer layer, or non-polyolefin material;
- wherein the multilayer films (F2) consist of the following layers:
- (a) an outer layer consisting of a polyolefin (PO);
- (b) a metal layer in contact with the outer layer (a), and
- wherein the polyolefin mixed recycling stream (B3) also comprises monolayer films of the desired polyolefin (PO),
- b3) milling, shredding or grinding the polyolefin mixed recycling stream (B3) to convert any pieces that are not in flaked form into flakes with a flake surface area in the range from 50 to 2500 mm2, thereby obtaining a polyolefin mixed recycling stream (B3) in flaked form;
- c3) treating the polyolefin mixed recycling stream (B3) in flaked form with an alkaline aqueous solution, thereby obtaining a treated recycling stream (C3) dispersed in the alkaline aqueous solution;
- d3) removing the alkaline aqueous solution, thereby obtaining the treated recycling stream (C3),
- e3) rinsing the treated recycling stream (C3) with solvent thereby removing all residue of the alkaline aqueous solution to obtain a rinsed recycling stream (D3);
- and
- f3) selecting those flakes present in the rinsed recycling stream (D3) that contain any material other than the desired polyolefin (PO) and removing these flakes from the treated recycling stream to leave a remaining recycling stream (E3) of the desired polyolefin (PO);
- g3) optionally extruding and pelletizing the recycling stream (E3) of the desired polyolefin (PO) to form pellets (P) of the desired polyolefin (PO),
- wherein step b3) can be omitted in the case that the pieces of the polyolefin mixed recycling stream (B3) are already in flaked form with a flake surface area in the range from 50 to 2500 mm2,
- wherein the desired polyolefin (PO) is selected from the group consisting of polypropylene and polyethylene.
16 more elements
Dependencies are inferred from the claim text.