WO2021116418A1

WO2021116418A1 - Plastic recycling

Info

Publication number: WO2021116418A1
Application number: PCT/EP2020/085780
Authority: WO
Inventors: René Bennet BORGGAARD
Original assignee: Gravenhorst Plast A/S
Priority date: 2019-12-13
Filing date: 2020-12-11
Publication date: 2021-06-17
Also published as: EP4072811A1

Abstract

A method comprising providing a feedstock comprising at least a first and a second polymer, and heating the feedstock at a temperature of about 130 °C to about 165 °C, preferably about 130 °C to about 160 °C, more preferably about 135 °C to about 145 °C, even more preferably about 140 °C, is described. The feedstock is heated during a time period of at least about 5 min, preferably about 5 min to about 180 min, more preferably about 5 min to about 100 min, even more preferably about 10 min to about 60 min, most preferably about 10 min to about 30 min.

Description

PLASTIC RECYCLING Technical field of the invention

Embodiments of the present invention relate to a method for recycling of mixtures of polymers and to a product prepared by such a method.

Technical background

Plastic recycling is a process of recovering plastic waste and reprocessing of the material into new products. Since the majority of plastic is non-biodegradable, recycling of plastic is a part of global efforts to reduce plastic in the waste streams, and especially all the plastic waste entering the Earth's ocean every year.

Compared with recycling of metal and glass, plastic polymers recycling is often more challenging, both from an economical and technical perspective. Recycling collection processes for plastic generally tend to lump all plastic products together. When different types of plastics are molten together, they tend to phase-separate, like oil and water, and set in layers. The phase boundaries cause structural weaknesses in the resulting material, and polymer blends are thus useful in only limited applications. The two most widely manufactured plastics, polypropylene and polyethylene, behave this way, which limits their utility for recycling. The plastic material thus needs to be sorted before processing, which is a time consuming and expensive process.

Embodiments of the present invention address a need to provide a method for providing recycled blends of polymers, which recycled blends are structurally strong and useful for many applications, where one example is plastic furnitures.

Summary of the invention

It is an object of an aspect of the present invention to provide an improvement over the above described techniques and known art. A specific objective is to improve the process of recycling of polymer blends, reducing the need for sorting of the different polymers before recycling processing.

At least some of these and other objects and advantages that will be apparent from the description have been achieved by a method comprising providing a feedstock comprising at least a first and a second polymer, heating the feedstock at a temperature of about 130 °C to about 165 °C, preferably about 130 °C to about 160 °C, more preferably about 135 °C to about 145 °C, even more preferably about 140 °C, wherein the feedstock is heated during a time period of at least about 5 min, preferably about 5 min to about 180 min, more preferably about 5 min to about 100 min, even more preferably about 10 min to about 60 min, most preferably about 10 min to about 30 min.

According to an aspect, the first and second polymer are not the same polymers.

According to an aspect, the feedstock is broken down into a particulate mass before heating.

According to an aspect, said breaking down the feedstock into a particulate mass comprises granulation, cutting, shredding and/or grinding.

According to an aspect, the feedstock is subject to molding during and/or after the heating.

According to an aspect, said molding of the feedstock comprises molding in a press.

According to an aspect, the method further comprises cooling of the feedstock after the heating.

According to an aspect, the method comprises cooling after the heating and/or molding, or alternatively during the molding.

According to an aspect, said cooling is conducted at a temperature of about 30 °C to about 60 °C, preferably about 40 °C to about 50 °C. According to an aspect, said first polymer is selected from the group consisting of polyethylene and thermoplastic polyesters.

According to an aspect, said second polymer is selected from the group consisting of polypropylene and silicone.

According to an aspect, the feedstock comprises polyethylene and polypropylene. According to an aspect, the polymers of the feedstock consist of polyethylene and polypropylene.

According to an aspect, the feedstock comprises polyethylene, polypropylene and silicone. According to an aspect, the polymers of the feedstock consist of polyethylene, polypropylene and silicone.

According to an aspect, the feedstock further comprises paper.

According to an aspect, the feedstock comprises about 40 vol.-% to about 90 vol.-% polyethylene and/or thermoplastic polyesters, preferably about 50 vol.-% to about 85 vol.-% polyethylene and/or thermoplastic polyesters, more preferably about 60 vol.-% to about 85 vol.-% polyethylene and/or thermoplastic polyesters.

According to an aspect, the feedstock comprises at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-%, of said second polymer. According to an aspect, said second polymer is polypropylene.

According to an aspect, the feedstock comprises about 40 vol.-% to about 90 vol.-% polyethylene, preferably about 50 vol.-% to about 85 vol.-% polyethylene, more preferably about 60 vol.-% to about 85 vol.-% polyethylene and at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-% polypropylene. According to an aspect, the feedstock comprises nylon.

According to an aspect, the feedstock preferably comprises less than 20 vol.-% nylon, preferably less than 15 vol.-% nylon, more preferably less than 13 vol.-% nylon.

According to an aspect, the feedstock is heated until it is in a semi-molten state.

According to an aspect, the method is for plastic recycling. According to an aspect, the method is for producing plastic products using a mixture of at least two different polymers.

According to an aspect, the method does not comprise a step of extrusion during and/or after the heating.

According to an aspect, the feedstock does not comprise any organic and/or inorganic solvents.

According to an aspect, the feedstock does not comprise sand.

According to an aspect, the method comprises only one heating step.

According to an aspect, the present invention relates to a plastic product obtained by a method according to the present invention. Brief description of the drawings

These and other aspects, features and advantages of which embodiments of the invention are capable of, will be apparent and elucidated from the following description of embodiments and aspects of the present invention, reference being made to the accompanying drawing, in which

FIG. 1 shows an example of an embodiment where a feedstock of the invention is heated in a container and molded in a press.

Detailed description

Specific embodiments of the invention will now be described with reference to the accompanying drawing. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like symbols/signs refer to like elements.

The terminology used herein is for the purpose of describing particular aspects of the disclosure only, and is not intended to limit the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be noted that the word “comprising” does not necessarily exclude the presence of other elements or steps than those listed and the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the example aspects may be implemented at least in part by means of both hardware and software, and that several “means”, “units” or “devices” may be represented by the same item of hardware.

The different aspects, alternatives and embodiments of the invention disclosed herein can be combined with one or more of the other aspects, alternatives and embodiments described herein. Two or more aspects can be combined. An embodiment of the invention is shown in FIG 1 , where a feedstock comprising at least a first and a second polymer is provided in a container. The feedstock may be heated to a temperature of about 130 °C to about 165 °C, preferably about 130 °C to about 160 °C, more preferably about 135 °C to about 145 °C, even more preferably about 140 °C. If the temperatures that are used are high, such as e.g. above 170 °C, said first and/or second polymer in the feedstock may burn, and as a result will no longer be present in the final product, i.e. it will not be recycled. The first and/or second polymer in the feedstock may work as a bonding agent, resulting in a strong and durable recycled polymer material.

Preferably, the feedstock is heated during a time period of at least about 5 min, preferably about 5 min to about 180 min, more preferably about about 5 min to about 100 min, preferably about 10 min to about 60 min, more preferably about 10 min to about 30 min, letting the feedstock achieve a semi-molten stage.

The feedstock may be broken down into a particulate mass before the heating step. This may be conducted in many different ways, where preferable examples comprise granulation, cutting, shredding, and/or grinding.

The feedstock may be washed before the heating step. It is preferably washed after being broken down into the particulate mass.

During and or after the heating step, the feedstock that has achieved a semi-molten stage may be subject to molding, e.g. using a press. The solid arrows in FIG. 1 show how pressure is applied in a downward direction. When the polymer feedstock has been heated for a sufficient time, the heat-treated feedstock starts to leak into the space between the container where the feedstock is heated and the press used for molding, as can be seen by the dashed arrows in FIG. 1 .

The container and/or mold used for the method of the present invention may be lubricated using e.g. wax, which results in that the final product is easily removed from the container or mold.

The heated feedstock may be subject to cooling after the heating and/or molding. Alternatively, it may be subject to cooling during the molding. Said cooling may be conducted at temperatures of about 30 °C to about 60 °C, preferably about 40 °C to about 50 °C. The heated feedstock may also be allowed to cool down without applying any cooling. The final product from the heated feedstock is easily removed when it has cooled down.

The first polymer is preferably selected from the group consisting of polyethylene and thermoplastic polyesters.

The second polymer of the feedstock may preferably be selected from the group consisting of polypropylene and silicone.

In one embodiment, the feedstock comprises polyethylene and polypropylene.

In one embodiment, the polymers of the feedstock consist of polyethylene and polypropylene.

In one embodiment, the feedstock comprises polyethylene, polypropylene and silicone. In one embodiment, the polymers of the feedstock consist of polyethylene, polypropylene and silicone.

In one embodiment the feedstock may comprise paper. The paper is preferably present in small amounts, preferably less than 5 vol.-%, e.g. less than 4 vol.-%, e.g. less than 3 vol.-%, e.g. less than 2 vol.-%, e.g. less than 1 vol.-%, of the feedstock. The feedstock may, in one embodiment, comprise about 40 vol.-% to about 90 vol.-% polyethylene and/or thermoplastic polyesters, preferably about 50 vol.-% to about 85 vol.-% polyethylene and/or thermoplastic polyesters, more preferably about 60 vol.-% to about 85 vol.-% polyethylene and/or thermoplastic polyesters

In one embodiment, the feedstock comprises about 40 vol.-% to about 90 vol.-% polyethylene, preferably about 50 vol.-% to about 85 vol.-% polyethylene, more preferably about 60 vol.-% to about 85 vol.-% polyethylene, as a first polymer.

According to one embodiment, the feedstock may comprise at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-%, of said second polymer.

The feedstock may, in one embodiment, comprise at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-%, polypropylene.

According to an embodiment, the feedstock comprises about 40 vol.-% to about 90 vol.- % polyethylene, preferably about 50 vol.-% to about 85 vol.-% polyethylene, more preferably about 60 vol.-% to about 85 vol.-% polyethylene and at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-% polypropylene. According to an embodiment, the feedstock comprising about 40 vol.-% to about 90 vol.- % polyethylene, preferably about 50 vol.-% to about 85 vol.-% polyethylene, more preferably about 60 vol.-% to about 85 vol.-% polyethylene and at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-% polypropylene, also comprises silicone. Further, it may comprise paper, as mentioned above.

According to one embodiment, the feedstock may comprise nylon. According to one embodiment, the nylon is preferably present in an amount of less than 20 vol.-% nylon, more preferably less than 15 vol.-% nylon, even more preferably less than 13 vol.-% nylon.

According to an embodiment, the feedstock may be heated until it reaches a semi-molten state.

According to an embodiment, the method does not comprise a step of extrusion after the heating, i.e. no extrusion process is conducted after the heating of the feedstock. The method according to the present invention is thus not intended to be used before any extrusion processes.

According to an embodiment, the feedstock does not comprise any organic and/or inorganic solvents. This gives a more environmentally friendly method and product.

According to an embodiment, the feedstock does not comprise sand.

The heating of the feedstock may be conducted in one, two, three or more heating steps. According to an embodiment, the method comprises only one heating step.

According to an embodiment, the feedstock preferably comprises at least 50 vol.-% polymers.

The present invention also relates to a plastic product obtained by a method according to the present invention.

The products obtained by the method according to the present invention may have different color patterns, depending on the colors of the polymers of the plastic products in the polymer feedstock.

The different aspects, embodiments and alternatives described above could be combined with one or more of the other described aspects, embodiments and alternatives.

Claims

1. A method comprising providing a feedstock comprising at least a first and a second polymer, heating the feedstock at a temperature of about 130 °C to about 165 °C, preferably about 130 °C to about 160 °C, more preferably about 135 °C to about 145 °C, even more preferably about 140 °C, wherein the feedstock is heated during a time period of at least about 5 min, preferably about 5 min to about 180 min, more preferably about 5 min to about 100 min, even more preferably about 10 min to about 60 min, most preferably about 10 min to about 30 min.

2. The method as claimed in any one of the previous claims, wherein the feedstock is broken down into a particulate mass before heating.

3. The method as claimed in claim 2, wherein breaking down the feedstock into a particulate mass comprises granulation, cutting, shredding and/or grinding.

4. The method as claimed in anyone of the previous claims, wherein the feedstock is subject to molding during and/or after the heating.

5. The method as claimed in claim 4, wherein said molding of the feedstock comprises molding in a press.

6. The method as claimed in any one of the previous claims, wherein the method further comprises cooling of the feedstock after the heating.

7. The method as claimed in any one of claims 4 to claim 6, wherein the method comprises cooling after the heating and/or molding, or alternatively during the molding.

8. The method as claimed in claim 6 or claim 7, wherein said cooling is conducted at a temperature of about 30 °C to about 60 °C, preferably about 40 °C to about 50 °C.

9. The method as claimed in any one of the previous claims, wherein said first polymer is selected from the group consisting of polyethylene and thermoplastic polyesters.

10. The method as claimed in any one of the previous claims, wherein said second polymer is selected from the group consisting of polypropylene and silicone.

11. The method as claimed in any one of the previous claims, wherein the polymers of the feedstock consist of polyethylene and polypropylene.

12. The method as claimed in any one of claims 1 to 10, wherein the polymers of the feedstock consist of polyethylene, polypropylene and silicone.

13. The method as claimed in any one of the previous claims, wherein the feedstock further comprises paper.

14. The method as claimed in any one of the previous claims, wherein the feedstock comprises about 40 vol.-% to about 90 vol.-% polyethylene and/or thermoplastic polyesters, preferably about 50 vol.-% to about 85 vol.-% polyethylene and/or thermoplastic polyesters, more preferably about 60 vol.-% to about 85 vol.-% polyethylene and/or thermoplastic polyesters.

15. The method as claimed in any one of the previous claims, wherein the feedstock comprises at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-%, of said second polymer.

16. The method as claimed in claim 15, wherein said second polymer is polypropylene.

17. The method as claimed any one of the previous claims, wherein the feedstock comprises about 40 vol.-% to about 90 vol.-% polyethylene, preferably about 50 vol.-% to about 85 vol.-% polyethylene, more preferably about 60 vol.-% to about 85 vol.-% polyethylene and at least 5 vol.-%, preferably at least 10 vol.-%, more preferably at least 15 vol.-% polypropylene.

18. The method as claimed in any one of the previous claims, wherein the feedstock comprises nylon.

19. The method as claimed in claim 18, wherein the feedstock comprises less than 20 vol.-% nylon, preferably less than 15 vol.-% nylon, more preferably less than 13 vol.-% nylon.

20. The method as claimed in any one of the previous claims, wherein the feedstock is heated until it is in a semi-molten state.

21. The method as claimed in any one of the previous claims, wherein the method does not comprise a step of extrusion.

22. The method as claimed in any one of the previous claims, wherein the feedstock does not comprise any organic and/or inorganic solvents.

23. The method as claimed in any one of the previous claims, wherein the feedstock does not comprise sand.

24. The method as claimed in any one of the previous claims, wherein the method only comprises one heating step.

25. Plastic product obtained by a method according to any one of claims 1 to 24.